JP2019032520A - Method for correcting photomask, method for producing photomask, photomask and method for manufacturing display device - Google Patents

Abstract

To provide a method for efficiently correcting a phase shift film under a stable condition and a related technique thereof.SOLUTION: There is provided a method for correcting a photomask comprising a pattern for transfer including a light transmitting portion, a light shielding portion and a semi-light transmitting portion with a width d1 (μm) that are formed by patterning a light-shielding film and a semi-light transmitting film on a transparent substrate. The method for correcting a photomask comprises: a step of identifying a defect generated in the semi-light transmitting portion; and a correction film formation step of forming a correction film at a position of identified defect, thereby forming a corrected semi-light transmitting portion with a width of d2 (μm). In the method, d1<3.0, the semi-light transmitting film has a transmittance T1 (%) with respect to a representative wavelength included in exposure light and has phase shift characteristics of shifting a phase of light with a representative wavelength by approximately 180 degrees, the correction film has a transmittance T2 (%) with respect to the representative wavelength and has phase shift characteristics of shifting the phase of the light with the representative wavelength by approximately 180 degrees, T2>T1 and d2<d1 or T2<T1 and d2>d1.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a method for correcting (repairing) a photomask that is advantageously used for manufacturing a display device, represented by a liquid crystal display or an organic EL display.

  Patent Document 1 describes a method of correcting a defective defect (white defect) or a surplus defect (black defect) defect in a semi-transparent portion of a multi-tone photomask. Here, the correction film is formed so that the phase difference with respect to the wavelength light of the i-line to g-line between the translucent part where the transparent substrate is exposed and the correction part where the correction film is formed is 80 degrees or less. .

  Patent Document 2 discloses a photomask provided with a transfer pattern formed by patterning a semi-transparent film and a light-shielding film formed on a transparent substrate, and the semi-transparent film is , The phase of the light of the representative wavelength in the wavelength range of i-line to g-line is shifted by approximately 180 degrees, and has a transmittance T1 (%) with respect to the representative wavelength. The transfer pattern has a transmittance T2 (%) lower than the transmittance T1 (%) of the semi-translucent film, and the transfer pattern is a main pattern having a diameter W1 (μm) formed of a transparent portion where the transparent substrate is exposed. An auxiliary pattern having a width d (μm) that is formed in the vicinity of the main pattern and is formed of a semi-transparent portion in which the semi-transparent film is formed on the transparent substrate, and the main pattern among the transfer patterns. And the auxiliary pattern is formed. And a photomask having a predetermined relationship between W1, T1, and d. The photomask is disposed in a region other than the region, and includes at least a light-shielding portion on which the light-shielding film is formed on the transparent substrate.

JP 2010-198006 A JP, 2006-024264, A

  At present, display devices including liquid crystal display devices, EL display devices, and the like are desired to be brighter and save power, and to improve display performance such as high definition, high speed display, and wide viewing angle.

  For example, in the case of a thin film transistor (“TFT”) used in the display device, a contact hole formed in an interlayer insulating film among the plurality of patterns constituting the TFT is surely an upper layer and a lower layer pattern. If there is no action to connect, correct operation is not guaranteed. On the other hand, for example, in order to increase the aperture ratio of a liquid crystal display device as much as possible to obtain a bright and power-saving display device, the diameter of the contact hole is required to be sufficiently small. Along with demands, it is desired to reduce the diameter of the hole pattern (for example, less than 3 μm). For example, a hole pattern having a diameter of 0.8 μm or more and 2.5 μm or less, and further a diameter of 2.0 μm or less is required. Specifically, formation of a pattern having a diameter of 0.8 to 1.8 μm is also a problem. Become.

  By the way, in the field of semiconductor device (LSI) manufacturing photomasks, which have a higher degree of integration and a markedly finer pattern than display devices, in order to obtain high resolution, the exposure device has a high aperture. There is a background in which an optical system of several NA (for example, 0.2 or more) is applied to shorten the wavelength of exposure light. As a result, in this field, KrF and ArF excimer lasers (single wavelengths of 248 nm and 193 nm, respectively) have been frequently used.

  On the other hand, in the lithography field for manufacturing display devices, it has not been common to apply the above-described method for improving the resolution. For example, the NA (numerical aperture) of an optical system of an exposure apparatus used in this field is about 0.08 to 0.15. Also, the exposure light source is often i-line, h-line, or g-line, and mainly uses a broad wavelength light source including these to irradiate a large area (for example, a rectangle having a side of 300 to 2000 mm). There is a strong tendency to focus on production efficiency and cost.

  However, in the manufacture of display devices, there is an increasing demand for pattern miniaturization as described above. Here, there are some problems in applying the technology for manufacturing a semiconductor device as it is to the manufacture of a display device. For example, conversion to a high-resolution exposure apparatus having a high NA (numerical aperture) requires a large investment and cannot be consistent with the price of the display apparatus. In addition, when changing the exposure wavelength (using a short wavelength such as an ArF excimer laser with a single wavelength), if it is applied to a display device with a large area, the production efficiency will be lowered and a considerable investment will be required. This is inconvenient. In other words, the problem of photomasks for manufacturing display devices is that, while pursuing unprecedented pattern miniaturization, cost and efficiency, which are existing merits, cannot be lost.

  Incidentally, the multi-tone photomask described in Patent Document 1 is known as a photomask for improving production efficiency mainly in the field of display device manufacturing. For example, as a transfer pattern, a multi-gradation pattern (for example, three gradations) obtained by adding a halftone part (semi-transparent part) to an existing binary mask having a light-shielding part and a translucent part is used. Thus, the number of repetitions of the photolithography process can be reduced in the manufacturing process of the display device. When this mask is used, a resist pattern having a three-dimensional structure in which the resist residual film thickness varies depending on the region can be formed on the transfer object by one exposure. Since this resist pattern is used as an etching mask when etching the lower layer film, it is reduced by ashing or the like and functions as an etching mask having a new shape. Therefore, patterning for two layers is performed by one exposure process. Can be done.

  The photomask defect correction method described in Patent Document 1 is applied to a defect generated in a semi-transparent portion of a multi-tone photomask. In this document, the correction part in which the correction film is formed on the transparent substrate has a phase difference of 80 degrees or less with respect to the light transmission part. Further, it is described that the phase difference of the correction portion with respect to the normal semi-transmission portion is 80 degrees or less.

  On the other hand, Patent Document 2 describes a photomask having a main pattern made of a light-transmitting portion, an auxiliary pattern made of a semi-light-transmitting portion arranged in the vicinity thereof, and a light-shielding portion formed in a region other than those. Has been. It is described that this photomask can significantly improve the aerial image of transmitted light by controlling the mutual interference of exposure light transmitted through both the main pattern and the auxiliary pattern. Unlike the above-described Patent Document 1, a semi-transparent film that shifts the phase of exposure light by approximately 180 degrees is used for the auxiliary pattern of the photomask. The photomask can be advantageously used when stably forming fine isolated holes on a transfer target such as a display panel substrate.

  As described above, it is effective to improve the transferability of the main pattern by disposing an appropriately designed auxiliary pattern that does not resolve directly on the transfer target with respect to the main pattern. However, such an auxiliary pattern is a finely designed fine pattern, and treatment in the case where a defect occurs at that position becomes a problem.

  In general, it is extremely difficult to reduce the occurrence of pattern defects to zero in the photomask manufacturing process. For example, a film defect (hereinafter also referred to as a white defect) or a surplus defect (hereinafter referred to as a black defect) may occur due to pinholes or foreign matter (particles) mixed in the film. Assuming such a case, a step of detecting this by inspection and correcting (repairing) by a correcting device is provided. The correction method is generally to deposit a correction film for white defects and to remove a surplus portion by irradiation with energy rays for black defects, and to deposit a correction film as necessary. is there. A white defect and a black defect can be corrected mainly by a FIB (focused Ion Beam) apparatus or a laser CVD (Chemical Vapor Deposition) apparatus.

  By the way, according to the study by the present inventors, there is a problem that even if the above method is used, it is difficult to correct depending on the type of the semi-translucent film. For example, in order to correct a defect generated in a semi-transparent film (that is, a phase shift film) having a function of shifting the phase of exposure light, it is desired to develop a correction film having similar optical characteristics. Here, the phase shift film used for the photomask has a phase shift action that inverts the phase of the light having the representative wavelength of the exposure light by approximately 180 degrees, and is specified for the light having the representative wavelength. The transmittance is as follows.

  Therefore, it is desired that the correction film is substantially equivalent to the optical characteristics of the phase shift film with reference to the optical characteristics.

  For example, a case where a correction film is formed in a laser CVD apparatus will be described as an example. First, a correction target area for correcting a detected defect is determined. The correction target region can be a white defect formed in a semi-transparent film (hereinafter also referred to as a normal film) or a white defect formed by removing a black defect. A local correction film (also referred to as a CVD film) is formed on the correction target region by laser CVD.

At this time, a source gas atmosphere as a raw material for the correction film is supplied to the photomask surface to form a source gas atmosphere. As a raw material for the correction film, metal carbonyl is preferably used. Specific examples include chromium carbonyl (Cr (CO) ₆ ), molybdenum carbonyl (Mo (CO) ₆ ), tungsten carbonyl (W (CO) ₆ ), and the like. As a correction film for the photomask, chromium carbonyl having high chemical resistance is preferably used.

For example, when chromium carbonyl is used as a raw material for the correction film, chromium hexacarbonyl (Cr (CO) ₆ ) is heated and sublimated, and this is guided to the correction target portion of the photomask together with a carrier gas (Ar gas or the like). . When this source gas atmosphere is irradiated with laser light, the source gas is decomposed by the heat / light energy reaction of the laser, and the product is deposited on the substrate, so that a correction film mainly composed of chromium is formed. The

  However, in the correction of the phase shift film, it is necessary not only to set the transmittance of the correction film deposited in the correction target region within a desired range, but also to satisfy the phase shift characteristic (approximately 180 degrees) at the same time. Is narrow.

  Furthermore, it is more difficult to correct a phase shift film having a relatively high transmittance (for example, 20% or more). This is because the transmittance is increased, the thickness of the correction film is decreased, and a slight variation in the thickness causes a large variation rate of the transmittance, making it difficult to satisfy a predetermined specification.

  As described above, the present inventors considered that there are many problems in the correction of the phase shift film, and it is a problem to propose a method for performing the correction efficiently under stable conditions.

  Therefore, an object of the present invention is to provide a method for efficiently correcting a phase shift film under stable conditions and a related technique.

(First aspect)
A photomask having a light-transmitting portion, a light-shielding portion, and a transfer pattern having a width d1 (μm) and having a translucent portion formed by patterning a light-shielding film and a semi-transparent film on a transparent substrate. A correction method,
Identifying a defect produced in the semi-translucent portion;
A correction film forming step of forming a correction film at the position of the identified defect to form a correction semi-transparent portion having a width d2 (μm);
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
The photomask correction method is characterized in that T2 <T1 and d2> d1.
(Second aspect)
The second aspect of the present invention is:
d1 and d2 are the photomask correction methods according to the first aspect, characterized in that the exposure apparatus that exposes the photomask has dimensions that do not resolve.
(Third aspect)
The third aspect of the present invention is:
In the photomask correction method according to the first or second aspect, the semi-translucent part is disposed in the vicinity of the translucent part via the light-shielding part. is there.
(Fourth aspect)
The fourth aspect of the present invention is:
The photomask correction method according to any one of the first to third aspects, wherein T2> T1, and a difference between T1 and T2 is in a range of 2 to 45.
(Fifth aspect)
According to a fifth aspect of the present invention,
d2 <d1 and the difference between d1 and d2 is 0.05 to 2.0. The photomask correction method according to any one of the first to fourth aspects, is there.
(Sixth aspect)
The sixth aspect of the present invention is:
In any one of the first to fifth aspects, a light-shielding supplementary film is formed at a position adjacent to the corrected semi-translucent portion before or after the correction film forming step. It is a correction method of the described photomask.
(Seventh aspect)
The seventh aspect of the present invention is
The semi-translucent part is disposed in the vicinity of the translucent part via the light-shielding part, and changes the light intensity distribution formed on the transferred body by the exposure light that passes through the translucent part, The photomask correction method according to any one of the first to sixth aspects, wherein an auxiliary pattern for increasing a depth of focus is configured.
(Eighth aspect)
The eighth aspect of the present invention is
The transfer pattern to which the correction method is applied is for forming a hole pattern on the transfer target,
A main pattern having a diameter W1 (μm) composed of the translucent portion;
An auxiliary pattern having a width d1 (μm), which is formed of the semi-translucent portion, disposed in the vicinity of the main pattern via the light shielding portion;
In the region excluding the main pattern and the auxiliary pattern, and including a light shielding portion surrounding the main pattern and the auxiliary pattern, according to any one of the first to seventh aspects. This is a photomask correction method.
(Ninth aspect)
The ninth aspect of the present invention provides
The method for correcting a photomask according to the eighth aspect, wherein the auxiliary pattern is a polygonal band or a circular band region surrounding the main pattern through the light shielding portion.
(Tenth aspect)
The tenth aspect of the present invention provides
A distance between the width center of the main pattern and the width center of the auxiliary pattern is a distance P1, and a distance between the width center of the main pattern and the width center of the correction auxiliary pattern made of the correction semi-transparent portion is P2. The photomask correction method according to the eighth or ninth aspect, wherein P1 = P2.
(Eleventh aspect)
The eleventh aspect of the present invention is
The photomask correction method according to any one of the first to tenth aspects, wherein the transfer pattern is a pattern for manufacturing a display device.
(Twelfth aspect)
The twelfth aspect of the present invention provides
A photomask manufacturing method comprising the photomask correction method according to any one of the first to eleventh aspects.
(13th aspect)
The thirteenth aspect of the present invention provides
In a photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern is:
The translucent part from which the transparent substrate is exposed;
The semi-transparent portion formed by forming a semi-transparent film having a width d1 (μm) on the transparent substrate;
Including the light-shielding portion in a region excluding the light-transmitting portion and the semi-light-transmitting portion;
Including a modified semi-transparent portion formed on the transparent substrate by a modified film having a width d2 (μm), which includes a material different from that of the semi-transmissive film;
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask characterized by T2 <T1 and d2> d1.
(14th aspect)
The fourteenth aspect of the present invention provides
A photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern has a normal transfer pattern and a corrected transfer pattern,
The normal transfer pattern is:
The translucent part from which the transparent substrate is exposed;
A semitranslucent film formed on the transparent substrate, and the semitranslucent part having a width d1 (μm) disposed in the vicinity of the translucent part via the light shielding part;
Including the light-shielding portion in a region excluding the light-transmitting portion and the semi-light-transmitting portion;
The modified transfer pattern is:
The translucent part from which the transparent substrate is exposed;
A correction film including a material different from the semi-transparent film is formed on the transparent substrate, and is disposed in the vicinity of the translucent part via the light-shielding part or the supplementary light-shielding part. Modified semi-translucent part with
Including the light shielding portion in a region excluding the light transmitting portion and the modified semi-light transmitting portion;
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask characterized by T2 <T1 and d2> d1.
(15th aspect)
The fifteenth aspect of the present invention provides
A photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern is:
A main pattern having a diameter W1 (μm) composed of the translucent portion;
A semi-transparent film is formed on the transparent substrate, and an auxiliary pattern having a width d1 (μm), which is disposed in the vicinity of the main pattern via the light-shielding portion, and includes the semi-transparent portion;
Including the light-shielding portion in a region excluding the main pattern and auxiliary pattern,
A correction film including a material different from that of the semi-transparent film is formed on the transparent substrate, and a width d2 including the modified semi-transparent part disposed near the main pattern via the light-shielding part. (Μm) correction auxiliary pattern,
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask characterized by T2 <T1 and d2> d1.
(Sixteenth aspect)
The sixteenth aspect of the present invention provides
A photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern has a normal transfer pattern and a corrected transfer pattern,
The normal transfer pattern is:
A main pattern having a diameter W1 (μm) composed of the translucent portion;
A semi-transparent film is formed on the transparent substrate, and an auxiliary pattern having a width d1 (μm), which is disposed in the vicinity of the main pattern via the light-shielding portion, and includes the semi-transparent portion;
Including the light-shielding portion in a region excluding the main pattern and the auxiliary pattern;
The modified transfer pattern is:
A main pattern having a diameter W1 (μm) composed of the translucent portion;
A modified semi-transparent portion formed on the transparent substrate by a correction film containing a material different from the semi-translucent film, and disposed near the main pattern via the light-shielding portion or the supplementary light-shielding portion. A correction auxiliary pattern having a width d2 (μm),
In the region excluding the main pattern and the correction auxiliary pattern, including the light shielding portion,
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask characterized by T2 <T1 and d2> d1.
(17th aspect)
The seventeenth aspect of the present invention provides
When the distance between the width center of the main pattern and the width center of the auxiliary pattern is P1, and the distance between the width center of the main pattern and the width center of the correction auxiliary pattern is P2, P1 = P2. The photomask according to the fifteenth or sixteenth aspect, wherein the photomask is characterized in that
(18th aspect)
The eighteenth aspect of the present invention provides
Any one of the fifteenth to seventeenth aspects, wherein the auxiliary pattern has a shape included in a region of a polygonal band or a circular band surrounding the main pattern through the light shielding portion. The photomask described in 1. above.
(19th aspect)
The nineteenth aspect of the present invention provides
The auxiliary pattern having the width d1 (μm) constitutes a part of an octagonal band area surrounding the periphery of the main pattern via the light shielding portion, and the correction auxiliary pattern is included in the octagonal band area. The photomask according to the fifteenth aspect, wherein the photomask has a shape to be formed.
(20th aspect)
According to a twentieth aspect of the present invention,
The semi-translucent portion is disposed in the vicinity of the translucent portion via the light-shielding portion, and has a depth of focus with respect to a transfer image formed on the transfer target by the exposure light transmitted through the translucent portion. The photomask according to any one of the thirteenth to nineteenth aspects, wherein the photomask is an auxiliary pattern for increasing the thickness.
(21st aspect)
According to a twenty-first aspect of the present invention,
d1 and d2 are the photomasks according to any one of the thirteenth to twentieth aspects, wherein the exposure apparatus that exposes the photomask has dimensions that do not resolve.
(Twenty-second aspect)
According to a twenty-second aspect of the present invention,
In any one of the thirteenth to twenty-first aspects, the transfer pattern has a supplementary light-shielding part made of a light-shielding supplementary film at a position adjacent to the modified semi-transparent part. It is a photomask of description.
(23rd aspect)
The twenty-third aspect of the present invention provides
The photomask according to any one of the thirteenth to twenty-second aspects, wherein T2> T1 and a difference between T1 and T2 is in a range of 2 to 45.
(24th aspect)
According to a twenty-fourth aspect of the present invention,
The photomask according to any one of the thirteenth to twenty-third aspects, wherein d2 <d1 and a difference between d1 and d2 is 0.05 to 2.0.
(25th aspect)
According to a twenty-fifth aspect of the present invention,
The transfer pattern is the photomask according to any one of the thirteenth to twenty-fourth aspects, which is for forming a hole pattern on a transfer target.
(26th aspect)
According to a twenty-sixth aspect of the present invention,
Using the photomask according to any one of the thirteenth to twenty-fifth aspects, irradiating the transfer pattern with exposure light including any of i-line, h-line, and g-line, A method of manufacturing a display device, including performing pattern transfer.

  According to the present invention, it is possible to provide a method for efficiently correcting a phase shift film under stable conditions and related techniques.

(A) is a photomask (Reference Example 1) as an embodiment to which the correction method of the present invention is applied, and includes a main pattern and an auxiliary pattern arranged in the vicinity of the main pattern (Photomask I) (B) is a cross-sectional schematic diagram of the AA position of (a). It is a plane schematic diagram which shows the pattern of the photomask of the reference example 2. It is a figure which shows the performance evaluation of each pattern for a transfer which concerns on the reference examples 1 and 2. FIG. It is a figure which shows the result of having simulated the relationship between the transmittance | permeability of the semi-transparent film used for the semi-transparent part of the photomask I, and the transfer performance (DOF, EL) which the photomask I shows. It is a figure which shows how DOF and EL change with the change of the width | variety d1 of a semi-transparent part when the transmittance | permeability of the semi-transparent part of the photomask I is 50%. It is a figure which shows how DOF and EL change with the change of the width | variety d1 of a semi-transparent part when the transmittance | permeability of the semi-transparent part of the photomask I is 60%. It is a figure which shows how DOF and EL change with the change of the width | variety d1 of a semi-transparent part when the transmittance | permeability of the semi-transparent part of the photomask I is 70%. It is a table | surface which shows the example of the combination of the transmittance | permeability T2 and the width | variety d2 of a semi-translucent part by the correction method of this invention. It is a plane schematic diagram which shows a mode that the semi-transmission part of the octagonal band which the photomask I has was divided into division AH. 3 is a schematic plan view illustrating an example of a black defect correcting method according to Embodiment 1. FIG. 10 is a schematic plan view illustrating an example of a white defect correction method according to Embodiment 2. FIG. FIG. 10 is a schematic plan view illustrating an example of a black defect correcting method in which an auxiliary pattern for one main pattern according to Example 3 is completely missing. It is a plane schematic diagram which illustrates the combination of an auxiliary pattern and a main pattern. 5 is a schematic cross-sectional view showing an example of a method for manufacturing photomask I. FIG.

[Photomask to be modified]
1A and 1B illustrate a photomask (hereinafter, photomask I) as an embodiment to which the correction method of the present invention is applied. Note that reference numerals are given only for the first appearance, and are omitted hereinafter.

  The photomask includes a transfer pattern having a light-transmitting portion 4, a light-shielding portion 3, and a semi-light-transmitting portion 5, which are formed by patterning a light-shielding film 12 and a semi-transparent film 11 on a transparent substrate 10. ing.

  The “transfer pattern” as used in the present application is a pattern designed based on a device to be obtained using a photomask, and is intended to be corrected later, or a corrected correction. All the finished transfer patterns are called according to the context.

  A photomask I shown in FIG. 1A includes a main pattern 1 and an auxiliary pattern 2 arranged in the vicinity of the main pattern.

In the photomask I, the main pattern is composed of a translucent portion where the transparent substrate is exposed, and the auxiliary pattern is composed of a semi-transparent portion having a width d1 in which a semi-transparent film is formed on the transparent substrate. Further, a region other than the main pattern and the auxiliary pattern and surrounding the main pattern and the auxiliary pattern is a light shielding part in which at least a light shielding film is formed on the transparent substrate.
Here, as shown in FIG. 1, the light shielding portion surrounding the main pattern and the auxiliary pattern includes an area adjacent to the main pattern and surrounding it, and an area adjacent to and surrounding the auxiliary pattern. It is a shading part including. That is, in the photomask I, a light-shielding portion made of a region other than the region where the main pattern and the auxiliary pattern are formed is formed.
The transfer pattern referred to here means a transfer pattern having the above-mentioned shape in design, and the shape is partially changed due to a defect (for example, a part of the light shielding portion surrounding the main pattern is partially Is not excluded).

  As shown in FIG. 1B, in the photomask I, the light-shielding portion has a semi-transparent film and a light-shielding film laminated on a transparent substrate, but it may be a light-shielding portion made only of the light-shielding film. Absent. The semi-transparent film has a phase shift characteristic that shifts the phase of exposure light used for exposing the photomask, preferably light of a representative wavelength in the wavelength range of i-line to g-line by about 180 degrees, It has a transmittance T1 (%) with respect to the representative wavelength.

  The light shielding film of the photomask I has an optical density of OD ≧ 2 with respect to the representative wavelength. Preferably, OD ≧ 3.

  The main pattern of the photomask I can form a hole pattern on a transfer target (such as a panel of a display device), and its diameter (W1) is preferably 4 μm or less. Transfer of a fine hole pattern of such a size necessary to realize a high-quality display device was difficult with an existing binary mask, but the photomask I controls the interference action of light, Excellent transfer performance is achieved by the design used.

Here, the auxiliary pattern composed of the semi-transparent part is in the vicinity of the translucent part, and is disposed at a position through the light shielding part between the translucent part, so that the exposure that transmits the translucent part is performed. The light intensity distribution formed on the transfer target by light is changed in a direction advantageous for transfer. This change in the light intensity distribution has the effect of, for example, increasing the peak of the light intensity formed by the light transmitted through the translucent part or increasing the depth of focus (DOF) of the transferred image. Further, it is advantageous in exposure margin (Exposure Latitude, EL), and can bring about an effect of increasing MEEF (mask error increasing coefficient).
In many phase shift masks, the anti-phase transmitted light interferes at the boundary where the semi-translucent portion and the translucent portion are adjacent to obtain an effect such as an improvement in contrast. A light shielding part is interposed between the light transmitting part and the light transmitting part so as to be separated from each other, and interference on the outer edge side (in which the amplitude is reversed) is obtained in the light intensity distribution of both transmitted light. is there.

  By exposing the photomask I, a fine main pattern (hole pattern) having a diameter W2 (μm) (where W1 ≧ W2) can be formed on the transfer target corresponding to the main pattern.

Specifically, W1 (μm) is expressed by the following formula (1).
0.8 ≦ W1 ≦ 4.0 (1)
If the relationship is satisfied, the effect of the present invention can be obtained more advantageously. This is because when the diameter is less than 0.8 μm, it becomes difficult to resolve the image on the transferred material, and when the diameter exceeds 4.0 μm, it is relatively easy to obtain resolution with an existing photomask. Related to that.

At this time, the diameter W2 (μm) of the main pattern (hole pattern) formed on the transfer target is preferably
0.6 ≦ W2 ≦ 3.0
It can be.

Moreover, when the diameter W1 of the main pattern is 3.0 (μm) or less, the effect of the present invention is more remarkably obtained. Preferably, the diameter W1 (μm) of the main pattern is
1.0 ≦ W1 ≦ 3.0
In addition,
1.0 ≦ W1 <2.5
It can be.
In order to obtain a finer transfer pattern for a display device,
0.6 ≦ W2 <2.5
Furthermore,
0.6 ≦ W2 <2.0
It is also possible.
The relationship between the diameter W1 and the diameter W2 can be W1 = W2, but preferably W1> W2. That is, when β (μm) is a bias value,
β = W1-W2> 0 (μm)
When
0.2 ≦ β ≦ 1.0,
More preferably,
0.2 ≦ β ≦ 0.8
It can be. When the photomask I is designed in this way, advantageous effects such as reducing the loss of the remaining resist pattern film thickness on the transfer target can be obtained.

  In the above, the diameter W1 of the main pattern means the diameter of a circle or a numerical value approximated thereto. For example, when the shape of the main pattern is a regular polygon, the diameter W1 of the main pattern is the diameter of the inscribed circle. If the shape of the main pattern is square as shown in FIG. 1A, the diameter W1 of the main pattern is the length of one side. The same applies to the diameter W2 of the transferred main pattern in that it is a circle diameter or a numerical value approximated to it.

  Of course, when trying to form a finer pattern, W1 can be 2.5 (μm) or less, or 2.0 (μm) or less, and W1 is 1.5 (μm). The present invention can also be applied as follows.

  The phase difference φ1 between the main pattern and the auxiliary pattern is approximately 180 degrees with respect to the representative wavelength of the exposure light used for exposure of the photomask having such a transfer pattern. For this reason, the semi-transparent film used for the auxiliary pattern has a phase shift characteristic that shifts the phase of the light by φ1 degrees, and φ1 is approximately 180 degrees.

  Here, “approximately 180 degrees” means within a range of 180 degrees ± 15 degrees. The phase shift characteristic of the semi-transparent film is preferably in the range of 180 ± 10 degrees, more preferably in the range of 180 ± 5 degrees.

  The exposure of the photomask I is particularly effective when exposure light including i-line, h-line, or g-line is used. In particular, exposure to broad wavelength light including i-line, h-line, and g-line is performed. It is preferable to apply as light. In this case, the representative wavelength can be any of i-line, h-line, and g-line. For example, the photomask of this embodiment can be configured using g-line as a representative wavelength.

The light transmittance T1 of the semi-translucent portion can be set as follows. That is, when the transmissivity of the semi-transparent film formed in the semi-transparent portion with respect to the representative wavelength is T1 (%),
2 ≦ T1 ≦ 95
Such a translucent portion transmittance enables control of an optical image of a transfer pattern, which will be described later.
Preferably,
20 ≦ T1 ≦ 80
And
More preferably,
30 ≦ T1 ≦ 70
More preferably,
35 ≦ T1 ≦ 65
It is. The transmittance T1 (%) is the transmittance of the representative wavelength in the semi-transparent film when the transmittance of the transparent substrate is used as a reference. This transmittance controls the amount of light having a phase opposite to that of the main pattern transmitted through the auxiliary pattern in cooperation with the setting of d1 (width of the auxiliary pattern) described later. In order to contribute to the action of improving transferability (for example, increasing DOF) due to the interference, the range is a good range.

  In the photomask of this aspect, the light-shielding portion that is disposed in a region other than where the main pattern and the auxiliary pattern are formed and that surrounds the main pattern and the auxiliary pattern can be configured as follows.

  The light-shielding part does not substantially transmit exposure light (light having a representative wavelength in the wavelength range of i-line to g-line), and a light-shielding film having an optical density OD ≧ 2 (preferably OD ≧ 3) is transparent. It can be formed on a substrate.

In the transfer pattern, when the width of the auxiliary pattern is d1 (μm),
0.5 ≦ √ (T1 / 100) × d1 ≦ 1.5 (2)
When this holds, an effect excellent in transferability of the photomask I can be obtained. At this time, the distance between the center of the width of the main pattern and the center of the auxiliary pattern in the width direction is defined as a distance P1 (μm), and the distance P1 is
1.0 <P1 ≦ 5.0
It is preferable that this relationship is established.
More preferably, the distance P1 is
1.5 <P1 ≦ 4.5
More preferably,
2.5 <P1 ≦ 4.5
It can be. By selecting such a distance P1, interference between the transmitted light of the auxiliary pattern and the transmitted light of the main pattern interacts satisfactorily, thereby obtaining an excellent effect such as DOF.

The width d1 (μm) of the auxiliary pattern is a dimension equal to or smaller than the resolution limit under the exposure conditions (exposure apparatus used) applied to the photomask. In general, considering that the resolution limit in an exposure apparatus for manufacturing a display device is about 3.0 μm to 2.5 μm (i-line to g-line), d1 is an exposure apparatus that exposes a photomask. The dimensions shall not be resolved. In particular,
d1 <3.0
And preferably
d1 <2.5,
More preferably,
d1 <2.0
More preferably, d1 <1.5
It is.

In addition, in order to make the transmitted light of the auxiliary pattern interfere well with the transmitted light of the main pattern,
d1 ≧ 0.7
More preferably,
d1 ≧ 0.8
It is preferable that
Further, d1 <W1 is preferable, and d1 <W2 is more preferable.
In such a case, the transferability of the photomask I is good, and a correction process described later is preferably used.

More preferably, the relational expression (2) is the following expression (2) -1, and more preferably the following expression (2) -2.
0.7 ≦ √ (T1 / 100) × d1 ≦ 1.2 (2) -1
0.75 ≦ √ (T1 / 100) × d1 ≦ 1.0 (2) -2
That is, the light amount of the inversion phase transmitted through the auxiliary pattern has an excellent effect when the balance between T1 and d1 satisfies the above.

  As described above, the main pattern of the photomask I shown in FIG. 1A is a square, but the photomask to which the present invention is applied is not limited to this. For example, as illustrated in FIG. 10, the main pattern of the photomask may have a rotationally symmetric shape including an octagon and a circle. The rotationally symmetric center can be set as a reference center for the P1.

  The shape of the auxiliary pattern of the photomask shown in FIG. 1 is an octagonal band, and this shape can be stably manufactured as an auxiliary pattern for forming a hole pattern and has a high optical effect. . However, the photomask to which the present invention is applied is not limited to this. For example, the shape of the auxiliary pattern is preferably a rotationally symmetric shape that is three or more times symmetric with respect to the center of the main pattern, with a certain width being given, and is illustrated in FIGS. 10 (a) to 10 (f). . As the design of the main pattern and the design of the auxiliary pattern, those different in FIGS. 10A to 10F may be combined.

  For example, the outer periphery of the auxiliary pattern is a regular polygon such as a square, regular hexagon, regular octagon, regular decagon, regular dodecagon, regular dodecagon, etc. (preferably regular 2n square, where n is an integer of 2 or more) Or the case where it is circular is illustrated. The shape of the auxiliary pattern is preferably a shape in which the outer periphery and the inner periphery of the auxiliary pattern are substantially parallel, that is, a shape such as a regular polygon or a circular band having a substantially constant width. This band shape is also called a polygonal band or a circular band. As the shape of the auxiliary pattern, it is preferable that such a regular polygonal band or a circular band surround the main pattern. At this time, the balance of the amount of light of the transmitted light of the main pattern and the transmitted light of the auxiliary pattern can be improved.

  Alternatively, the shape of the auxiliary pattern preferably completely surrounds the periphery of the main pattern via the light shielding portion, but may be a shape in which a part of the polygonal band or the circular band is missing. The shape of the auxiliary pattern may be, for example, a shape in which the corners of the rectangular band are missing as shown in FIG.

  In addition to the main pattern and the auxiliary pattern, other patterns may be additionally used as long as the effects of the present invention are not hindered.

  Next, an example of a method for manufacturing the photomask I will be described below with reference to FIG. As in FIG. 1, the reference numerals are given only for the first appearance, and the rest are omitted.

  As shown in FIG. 11A, a photomask blank is prepared.

  In this photomask blank, a translucent film and a light-shielding film are formed in this order on a transparent substrate made of glass or the like, and a first photoresist film 13 is further applied.

  The semi-transparent film is preferably made of a material that satisfies the above-described transmittance T1 and phase difference φ1 and can be wet etched. However, if the amount of side etching that occurs during wet etching becomes too large, inconveniences such as deterioration of CD accuracy and destruction of the upper layer film due to undercutting occur. Therefore, the film thickness range is preferably 2000 mm or less. For example, it is in the range of 300 to 2000 mm, more preferably 300 to 1800 mm. Here, CD is a critical dimension, and is used in the present specification to mean a pattern width.

  Moreover, in order to satisfy these conditions, it is preferable that the translucent film material has a refractive index of a representative wavelength (for example, h-line) included in exposure light of 1.5 to 2.9. More preferably, it is 1.8 to 2.4.

  Furthermore, it is preferable that the translucent film has a pattern cross-section (surface to be etched) formed by wet etching that is nearly perpendicular to the main surface of the transparent substrate.

  In consideration of the above properties, as a film material of the semi-transparent film, a material containing a metal and Si, more specifically, a material containing any of Zr, Nb, Hf, Ta, Mo, Ti and Si, or These materials can be made of oxides, nitrides, oxynitrides, carbides, or materials containing oxynitride carbides. As a method for forming the semi-translucent film, a known method such as a sputtering method can be applied.

  A light shielding film is formed on the semi-transparent film of the photomask blank. As a film forming method, a known means such as a sputtering method can be applied as in the case of the semi-transparent film.

  The material of the light shielding film may be Cr or a compound thereof (oxide, nitride, carbide, oxynitride, or oxynitride carbide), or a metal silicide including Mo, W, Ta, Ti, or The above compound of the silicide may be used. However, the material of the light-shielding film of the photomask blank is preferably a material that can be wet-etched in the same manner as the semi-transparent film and has etching selectivity with respect to the semi-transparent film material. That is, it is desirable that the light-shielding film is resistant to the etching agent for the semi-transparent film, and that the semi-transparent film is resistant to the etching agent for the light-shielding film.

  A first photoresist film is further applied on the light shielding film of the photomask blank. Since the photomask of this embodiment is preferably drawn by a laser drawing apparatus, it is a photoresist suitable for it. The first photoresist film may be a positive type or a negative type, but will be described below as a positive type.

  Next, as shown in FIG. 11B, a drawing apparatus is used to draw the first photoresist film using drawing data based on the transfer pattern (first drawing). Then, the light shielding film is wet-etched using the first resist pattern 13p obtained by development as a mask. Thus, a region to be a light shielding part is defined, and an auxiliary pattern region surrounded by the light shielding part (light shielding film pattern 12p) is defined.

  Next, as shown in FIG. 11C, the first resist pattern is removed.

  Next, as shown in FIG. 11D, a second photoresist film 14 is applied to the entire surface including the formed light shielding film pattern.

  Next, as shown in FIG. 11E, a second drawing is performed on the second photoresist film to form a second resist pattern formed by development. The semi-transparent film is wet etched using the second resist pattern 14p and the light shielding film pattern as a mask. By this etching (development), a main pattern region is formed which includes a light-transmitting portion from which the transparent substrate is exposed. The second resist pattern covers the region serving as the auxiliary pattern and has an opening in the region serving as the main pattern made of the light transmitting portion, and the second resist pattern is exposed so that the edge of the light shielding film is exposed from the opening. It is preferable to perform sizing on the drawing data of drawing. By doing so, it is possible to absorb the misalignment that occurs between the first drawing and the second drawing, and to prevent the CD accuracy of the transfer pattern from deteriorating. Can be matched.

  Next, as shown in FIG. 11F, the second resist pattern is peeled off to complete the photomask I of this embodiment shown in FIG.

  However, wet etching can be applied when manufacturing such a photomask. Since wet etching has the property of isotropic etching, the width d1 of the auxiliary pattern should be 1 μm or more, preferably 1.2 μm or more from the viewpoint of ease of processing, considering the thickness of the semi-transparent film. Is useful.

  The transfer performance of the photomask I of this embodiment shown in FIG. 1 was compared and evaluated by optical simulation.

  Here, reference examples 1 and 2 are prepared as transfer patterns for forming a hole pattern on a transfer target, and what transfer performance is exhibited when exposure conditions are set in common. An optical simulation was performed.

(Reference Example 1)
The photomask of Reference Example 1 is a photomask having the same configuration as that of the photomask I. Here, the main pattern composed of the translucent part is a square having a side (diameter) (that is, W1) of 2.0 (μm), and the auxiliary pattern composed of the semi-translucent part has a width d1 of 1.3 (μm). A square band is used, and a distance P1 that is a distance between the center of the main pattern and the width center of the auxiliary pattern is set to 3.25 (μm).

  The auxiliary pattern is formed by forming a semi-transparent film on a transparent substrate. The translucent film has a g-line transmittance T1 of 45 (%) and a phase shift amount of 180 degrees. The light shielding portion surrounding the main pattern and the auxiliary pattern is made of a light shielding film (OD> 2) that does not substantially transmit exposure light.

(Reference Example 2)
As shown in FIG. 2, the photomask of Reference Example 2 has a so-called binary mask pattern composed of a light shielding film pattern formed on a transparent substrate. In this photomask, a square main pattern composed of a light transmitting portion from which a transparent substrate is exposed is surrounded by a light shielding portion. The diameter W1 (one side of the square) of the main pattern is 2.0 (μm).

  In any of the photomasks of Reference Examples 1 and 2, a hole pattern having a diameter W2 of 1.5 μm is formed on the transfer target, and the exposure conditions applied in the simulation are as follows. That is, the exposure light was a broad wavelength including i-line, h-line, and g-line, and the intensity ratio was g: h: i = 1: 1: 1.

  The optical system of the exposure apparatus has an NA of 0.1 and a coherence factor σ of 0.5. The film thickness of the positive photoresist for grasping the cross-sectional shape of the resist pattern formed on the transfer target was 1.5 μm.

  FIG. 3 shows the performance evaluation of each transfer pattern under the above conditions.

[Optical evaluation of transferability]
For example, in order to transfer a fine light-transmitting pattern with a small diameter, the profile of the transmitted light intensity curve must be good due to the aerial image formed by exposure light after passing through the photomask on the transfer target. Specifically, the peak that forms the peak of transmitted light intensity is sharp, rising in a nearly vertical manner, and the absolute value of the peak light intensity is high (when a sub-peak is formed around it). Is sufficiently high relative to its strength).

When the photomask is more quantitatively evaluated from the optical performance, the following indices can be used.
(1) Depth of Focus (DOF)
The depth of focus for the fluctuation range to be within a predetermined range (here, ± 15%) with respect to the target CD. When the numerical value of DOF is high, it is difficult to be influenced by the flatness of a transfer target (for example, a panel substrate for a display device), a fine pattern can be formed reliably, and CD variation can be suppressed.
(2) Exposure margin (EL: Exposure Latitude)
The margin of exposure light intensity for the fluctuation range to be within a predetermined range (here, within ± 15%) with respect to the target CD.
Based on the above, when evaluating the performance of each sample to be simulated, as shown in FIG. 3, the photomask of Reference Example 1 has a very excellent depth of focus (DOF) compared to Reference Example 2, Shows stable transfer of patterns.

In addition, the photomask of Reference Example 1 shows an excellent numerical value of 10.0 (%) or more even in EL, that is, enables stable transfer conditions with respect to fluctuations in the amount of exposure light.
Furthermore, the Dose value required for exposure of the photomask of Reference Example 1 is considerably smaller than that of Reference Example 2. This shows the merit that the exposure time does not increase or can be shortened even in the case of manufacturing a large area display device in the case of the photomask of Example 1.

[Defect correction method]
Hereinafter, the correction method according to the present invention will be described by taking as an example a process of correcting (repairing) defects detected in the auxiliary pattern (semi-transparent portion) of the photomask I.

  In correcting the semi-translucent portion, a correction film having the same optical characteristics as that of the normal film may be used. However, while a normal film is formed by applying a sputtering method or the like, a correction film that requires local deposition of a film material is different from the normal film by using a different method. It is a film | membrane containing. Since the deposition of the local film material has a narrow range of stable film forming conditions, it is practically difficult to form a film satisfying both transmittance and phase characteristics at the same time. In view of this, the present inventors have examined a modification that can exhibit the above-mentioned optical action of the photomask I almost in the same manner even if the shape and physical properties thereof are not the same as the semi-transparent portion made of a normal film.

  FIG. 4 shows the result of simulating the behavior change of the photomask when the transmissivity of the semitransparent film used for the semitransparent portion of the octagonal band of the photomask I varies. In the basic design of the photomask I (reference example 1) shown in FIG. 1, the transmissivity T1 of the semi-translucent portion is 45% as described above, and the DOF at this time is 33.5 (μm), EL Indicates 10.4 (%) (FIGS. 3 and 4).

  Here, when the transmissivity of the semi-transparent portion is increased while the width of the semi-transparent portion is fixed to the above value and the phase shift amount is set to 180 degrees, the numerical value of DOF increases while the EL increases. It turns to decrease and becomes almost zero when the transmittance reaches 60%.

  Next, in FIGS. 5A to 5C, when the transmissivity of the auxiliary pattern made of the semi-transparent portion is set to a value within the range of 50 to 70%, respectively, due to the change in the width (CD) of the semi-transparent portion, The result of having investigated by simulation how DOF and EL change will be shown. According to this study, in any transmittance, there is a portion where EL exceeds 10% in the vicinity of the peak, and the DOF is within the allowable range (for example, 25 μm or more, preferably 30 μm or more). It turns out that it is possible. Note that conditions suitable for both DOF and EL can be obtained in the region surrounded by the dotted line in FIGS. From these results, FIG. 5D shows an example of a preferable combination of transmittance and width of the semi-translucent portion.

  In other words, FIG. 4 shows that the variation in the transmittance of the auxiliary pattern composed of the semi-transparent portion deteriorates the EL, but this deterioration tendency of the EL is almost recovered by the change in the width of the auxiliary pattern. It has become clear from FIGS. 5A to 5C. In the above example, the case where the correction film having the transmittance higher than the transmittance of the semi-translucent portion has been described, but the correction film having the transmittance lower than that of the semi-transparent portion is corrected. For this purpose, a modification for increasing the width d1 of the auxiliary pattern may be applied. Therefore, when a defect occurs in the auxiliary pattern (width d1) composed of the semi-transparent portion (transmittance T1) and this is corrected by the correction film, a correction film having a transmittance (T2) different from that of the normal film is used. However, the normal auxiliary pattern can be replaced by appropriately using the width (d2) of the auxiliary pattern different from that of the normal film. Then, the correction auxiliary pattern composed of the correction semi-transparent portion formed by this correction film adjusts the transmitted light having a phase opposite to that of the light transmission portion to an appropriate light amount in the same manner as the normal auxiliary pattern. It can be understood that it can interfere with the transmitted light by the pattern.

In other words, in a semi-transmission part having a phase shift characteristic and a predetermined width, an optical image is formed by transmitted light having an inverted phase by a combination of the value of T1 and the value of d1, and one excess or deficiency is compensated by the other. It is possible. The transmissivity of the semi-transparent film is T1, the transmissivity of the correction film is T2, and the width of the semi-transparent portion (that is, the width of the auxiliary pattern, hereinafter also referred to as “normal auxiliary pattern width”) is d1. If the width of the modified semi-translucent portion (that is, the width of the correction auxiliary pattern) is d2,
T2> T1 and d2 <d1
Or
T2 <T1 and d2> d1
It can be.
However, even in the case of d2> d1, it is desirable that the width d2 is smaller than the resolution limit of the exposure apparatus that exposes the photomask, similarly to the width d1. The specific dimensions are the same as those described for d1 above.

  As described above, even when it is difficult to obtain the same optical characteristics (transmittance, phase shift amount) as that of a normal film, the range of conditions for obtaining a stable deposition condition of the correction film is narrow in the photomask defect correction. It is extremely meaningful to obtain a correction auxiliary pattern that performs the same function as a normal auxiliary pattern.

[Defect correction example]
Based on the above verification results, a specific example of a process for performing a photomask correction method will be described.

<Example 1 (in the case of black defect 1)>
A case where a black defect occurs in the auxiliary pattern formed of the semi-transparent portion of the photomask of Reference Example I will be described. For example, it is assumed that when the semi-transparent portion of the octagonal band included in the photomask I is divided into sections A to H as shown in FIG. That is, the type and position of the defect are specified here.

  In this case, if necessary, a correction device is used to form a light-shielding correction film (hereinafter referred to as a supplement film) having an optical density equivalent to that of the light-shielding film (OD ≧ 2) in a desired region including a defect position. Then, pre-processing for adjusting the shape of the black defect may be performed (FIG. 7A). A portion where the shape of the black defect is arranged with the supplement film, that is, a region of the supplement film is denoted by 17. It is preferable that the region 17 of the replenishment film is a quadrangle (square or rectangular). Although the supplementary film region 17 shown in FIG. 17A has the same width as the normal auxiliary pattern, it may be larger or smaller than the normal auxiliary pattern. The shape of the black defect that has occurred may be adjusted to the above-mentioned square shape.

  Next, based on the verification result, the modified semi-transmission part width (CD) and the transmittance are selected so that an optical action substantially equivalent to that of the normal auxiliary pattern can be obtained by the modified film. For example, when T2 of the correction film is larger than T1 (here 45%), the correction auxiliary pattern width d2 is made smaller than the normal auxiliary pattern width d1, and an appropriate combination of T2 and d2 is selected. It is preferable to grasp an appropriate combination of both with reference to the correlation illustrated in FIG. 5D in advance. For example, T2 can be 50% and d2 can be 1.20 μm. Note that the phase shift amount of the correction film is approximately 180 degrees as in the normal film.

  The replenishment film portion having the width thus determined is removed, and the transparent substrate is exposed to define a correction film formation region (FIG. 7B). Laser zapping or FIB (focused ion beam) method or the like can be applied as the film removing means. Reference numeral 18 denotes a portion where the supplementary film has been removed, that is, a correction film formation region. Then, a correction film forming step of forming a correction film in the correction film 15 forming region, that is, the correction target region is performed (FIG. 7C). If the correction film forming region 18 is also square (rectangular or square), it is easy to uniformly deposit the correction film.

  Note that, for example, a laser CVD apparatus can be suitably used for forming the supplementary film and the correction film. Also, the same membrane material as that of the correction membrane can be used. When forming the replenishment film, film formation conditions (laser power, gas flow rate, or film formation time) different from those of the correction film are applied to form a film having a high light-shielding property with different film properties (film density, etc.). it can.

  As a result, a semi-transparent portion including a defect is corrected, and a modified semi-transparent portion made of a correction film having a narrower width is formed. The shape is surrounded by a light shielding portion (also referred to as a supplementary light shielding portion) formed by the replenishment film.

  Note that the black defect shape adjustment, film removal, and correction film formation do not necessarily need to be performed in the above order. Finally, the correction film having the selected transmittance and phase characteristics is determined. What is necessary is just to make it the state of FIG. For example, the semi-transparent film (normal film) is first removed from a predetermined region including the generated black defect to obtain a portion 18 where the film is removed (FIG. 7D), and the correction film 15 is formed with a predetermined width. After the formation (FIG. 7E), the replenishment film 16 may be formed on both outer sides (FIG. 7F).

  As a result, the corrected transfer pattern has a translucent portion (main pattern) from which the transparent substrate is exposed and a modified semi-transparent portion made of a correction film containing a material different from the semi-transparent film. The modified semi-translucent portion has a width d2 (μm) disposed in the vicinity of the translucent portion via a light shielding portion or a supplementary light shielding portion. The area excluding the translucent part and the modified semi-translucent part is configured by the light shielding part or by the light shielding part and the supplementary light shielding part.

  If there is a remaining normal translucent part, this constitutes a part of the octagonal band. Here, since d2 <d1, the modified semi-translucent portion is arranged so as to be included in the region of the octagonal band. For example, as shown in FIG. 7C, it is preferable that the two sides forming the edge of the modified semi-translucent portion are arranged in parallel with the two sides forming the edge of the normal semi-translucent portion.

  However, it is more preferable that the correction film is formed at the center in the width direction of the octagonal band (that is, the normal semi-transparent region). In other words, the value of the distance (distance P2) between the center of the main pattern and the width center of the auxiliary correction pattern after correction does not change compared to the value (distance P1) before correction (that is, P1 = P2). It is preferable to set the formation position of the correction film (see FIG. 7C). That is, here, the width d2 of the correction film is d2 <d1 with respect to the width d1 of the normal film before correction, but the width center position of the correction film is the case where no defect occurs (that is, the design value). It should be the same as the width center position of the auxiliary pattern. This is to prevent the peak position of the light intensity distribution of the transmitted light formed by the correction auxiliary pattern from changing from that of the normal film.

  As a result, when the photomask after correction is transferred, the optical image formed by the exposure light that passes through the auxiliary pattern including the defect correction portion is almost the same as that when there is no defect, and this optical image is the main pattern. Interfering with an optical image of light passing through the lens, and exhibit excellent transfer characteristics (eg, DOF, EL).

<Example 2 (in the case of white defect)>
A case where a white defect occurs in the auxiliary pattern of the photomask I is illustrated in FIG. For example, it is assumed that when a semi-transparent portion of an octagonal band included in the photomask I is divided into sections A to H as shown in FIG. That is, the position and type of the defect are specified here.
First, as shown in FIG. 8A, the shape of the white defect may be adjusted by removing the film near the white defect, if necessary. The code | symbol of the part which removed the film | membrane of the vicinity of a white defect is set to 19. Moreover, the white defect formed by removing the surplus of the black defect which has arisen can also be used as the correction target of this aspect.
Then, the replenishment film 16 is formed in the region including the defect to artificially form a black defect (FIG. 8B). Thereafter, correction is performed in the same manner as in the black defect correction method (FIGS. 7A, 7B, and 7C).

<Example 3 (2 in the case of a black defect)>
FIG. 9A shows a black defect in which a plurality of patterns shown in FIG. 1A are arranged on the same plane and the auxiliary pattern for one main pattern is completely missing. The black defect may be a black defect formed by using a supplementary film after adjusting the shape of the generated black defect, or a black defect obtained by forming a supplementary film in a region including the generated white defect. There may be.

  In this case, it is effective to form auxiliary patterns corresponding to all of the sections A to H (FIG. 6). However, the correction process is the same as that in the first embodiment. That is, prior to the formation of the correction film, the combination of the transmittance T2 and the width d2 of the correction film to be formed is selected here as in the first embodiment. That is, the transmittance T2 of the correction film is made larger than the transmittance T1 (for example, 45%) of the semi-transparent film (normal film), and the correction auxiliary pattern width d2 is made smaller than the normal auxiliary pattern width d1. For example, T2 can be 50% and d2 can be 1.20 μm. Here, the phase shift amount of the correction film is approximately 180 degrees here.

  Next, similarly to FIG. 7B, the film is removed based on the determined width, and the transparent substrate in the region where the correction film is formed is exposed. Then, a correction film having the determined transmittance is formed in this region (FIG. 9B). Of course, the order of FIGS. 7D, 7E and 7F may be followed.

  In the present embodiment, the case of d2 <d1 has been described. On the other hand, when d2> d1, when the defect is corrected, the semi-transparent film which is a normal film and the light shielding film adjacent thereto are removed with a necessary width to expose the transparent substrate, and the correction film is formed in this region. Form. In this case, the transmittance T2 of the correction membrane is smaller than the transmittance T1 of the normal membrane. Note that d2 is a dimension that is not resolved by the exposure apparatus that exposes the photomask (for example, d2 <3.0).

  The correction method of the present invention is not limited to a photomask having a photomask I design. By the correction method of the present invention, the defect generated in the semi-transparent portion having the phase shift characteristic of the predetermined width is corrected, and the optical image formed by the transmitted light has substantially the same function as the normal semi-transparent portion. Needless to say, the present invention is applicable to photomasks of other designs as well. Depending on the design of the transfer pattern, the optimal transmittance and CD value can be obtained by optical simulation.

[Photomask of the present invention]
The present invention includes a photomask (referred to as photomask II) subjected to the above-described modification.

In the photomask of the present invention, a transfer pattern is formed on a transparent substrate, as illustrated in FIGS. 7C and 9B.
This transfer pattern is
A transparent portion where the transparent substrate is exposed; and
A semi-transparent film formed on a transparent substrate, and having a width d1 (μm);
It includes a light shielding portion in a region excluding the light transmitting portion and the semi-light transmitting portion.
The semi-translucent part is disposed in the vicinity of the translucent part via a light shielding part. That is, the light shielding part is sandwiched between the semi-translucent part and the translucent part. Here, the vicinity means that the transmitted light of the two is at a distance that can cause mutual interaction and change the profile of the optical image.
In the transfer patterns shown in FIGS. 7C and 9B, the translucent portion constitutes the main pattern and the semi-transparent portion constitutes the auxiliary pattern.

  In addition, the photomask (photomask II) of the present invention is obtained by correcting defects generated in the semi-translucent portion of the photomask I. Specifically, the photomask II includes a modified semi-transparent portion having a width d2 (μm) formed by forming a correction film on a transparent substrate, which is a region of a normal semi-transparent portion (here, , A regular octagonal band region). That is, the modified semi-transparent part has a shape included in the normal semi-transparent part region.

  Further, the normal semi-transparent portion included in the photomask II forms a part of the regular octagonal band region (see FIG. 7C).

  The shape of the normal semi-translucent portion can be grasped by referring to another pattern included in the same transfer pattern (see FIG. 9B).

  The ranges of the diameter W1 of the main pattern, the transmittance T1 of the semi-translucent portion, and the width d1 of the auxiliary pattern are as described above.

  The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by φ1 (degrees), and is corrected. The film has a transmittance T2 (%) with respect to the representative wavelength and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by φ2 (degrees).

φ1 and φ2 are approximately 180 degrees. As described above, approximately 180 degrees is a range of 180 ± 15 degrees.
Preferably, φ2 can be in the range of φ1 ± 10, more preferably φ1 ± 5.

Also,
T2> T1 and d2 <d1, or
T2 <T1 and d2> d1
However, T2> T1 and d2 <d1 are preferable. In this case, a CVD film having a stable film thickness is easily obtained.

  The range of T2 is preferably 40 ≦ T2 ≦ 80, more preferably 40 to 75.

  Moreover, it is preferable that the difference of T1 and T2 is 2-45, More preferably, it is 2-35. In this case, by adjusting the width of the modified semi-translucent portion, it is possible to cause an optical action substantially similar to that of a normal semi-translucent portion.

  Furthermore, d2 <d1 is preferable, and the difference between d1 and d2 is 0.05 to 2.0.

  Moreover, when d1 is 2 micrometers or less, it is preferable to make the difference of d1 and d2 into the range of 0.05-1.5, More preferably, it is 0.05-1.0, More preferably, it is 0.05. ~ 0.5.

  In such a range, the transmittance T2 of the correction assisting pattern can contribute to the formation of an optical image substantially equivalent to the function of the normal pattern by cooperation with the width d2, and is stable as a CVD laser film. Deposition conditions can be selected. A range in which the transferability (DOF, EL) of the photomask II is good can be adopted.

In the third embodiment described above (in the case of black defect 2), in the transfer pattern in which a plurality of patterns shown in FIG. 1A are arranged on the same surface, the auxiliary pattern for one main pattern is complete. An example of correcting the missing black defect is shown. The transfer pattern of the photomask II thus corrected may have a normal transfer pattern and a corrected transfer pattern.
The “normal transfer pattern” referred to here is a pattern in which a plurality of patterns shown in FIG. 1A in one photomask do not have black defects or white defects and are not corrected (for example, FIG. 1). 9 (b) below). The “corrected transfer pattern” refers to a pattern in which an auxiliary pattern for one main pattern is completely deleted as shown in the upper diagram of FIG. 9B, for example.
That is, the photomask II may include both a normal transfer pattern and a transfer pattern in which the auxiliary pattern is completely missing as described above.

The present invention also includes a photomask manufacturing method including the correction method described above.
For example, it can be set as the manufacturing method of the photomask II.

  In the manufacturing method of the photomask I described above, when a defect occurs in the formed semi-translucent portion, the correction method of the present invention can be applied. In that case, for example, a defect inspection step and a correction step may be provided after the second resist stripping step shown in FIG. 11F, and the correction method of the present invention may be applied in the correction step.

  The present invention includes a method for manufacturing a display device, including a step of exposing the above-described photomask of the present invention by an exposure apparatus and transferring the transfer pattern onto a transfer target. Here, the display device includes a device for configuring the display device.

  In the method for manufacturing a display device of the present invention, first, the above-described photomask of this aspect is prepared. Next, the transfer pattern is exposed to form a hole pattern having a diameter W2 of 0.6 to 3.0 μm on the transfer target.

  As the exposure machine to be used, a system that performs projection exposure at the same magnification, and the following are preferable. That is, it is an exposure machine used for FPD, and its configuration is such that the numerical aperture (NA) of the optical system is 0.08 to 0.15 (coherence factor (σ) is 0.4 to 0.9). , I-line, h-line, and g-line having a light source including exposure light. However, even in an exposure apparatus having a numerical aperture NA of 0.10 to 0.20, it is of course possible to obtain the effects of the invention by applying the present invention.

  The light source of the exposure apparatus to be used may use modified illumination (oblique illumination such as annular illumination), but the excellent effect of the invention can be obtained even with non-deformed illumination.

  There is no restriction | limiting in particular in the use of the photomask to which this invention is applied. The photomask of the present invention can be a transmissive photomask that can be preferably used in the manufacture of display devices including liquid crystal display devices and EL display devices.

  According to the photomask of the present invention using the semi-transmission part in which the phase of the transmitted light is inverted, the mutual interference of the exposure light transmitted through both the main pattern and the auxiliary pattern is controlled, and the zero order light is reduced during the exposure. The ratio of ± 1st order light can be relatively increased. For this reason, the aerial image of transmitted light can be significantly improved.

  As an application in which such an effect can be advantageously obtained, it is advantageous to use the photomask of the present invention for forming isolated hole patterns such as contact holes frequently used in liquid crystals and EL devices. There are two types of patterns: a dense pattern in which a large number of patterns are arranged with a certain regularity so that they have an optical influence on each other, and an isolated pattern in which such a regular arrangement pattern does not exist. In many cases, a pattern is distinguished from a pattern. The photomask of the present invention is particularly preferably applied when an isolated pattern is to be formed on a transfer target.

  As long as the effects of the present invention are not impaired, an additional optical film or functional film may be used for the photomask to which the present invention is applied. For example, a light shielding film may be formed in a region other than the transfer pattern in order to prevent inconvenience that the light transmittance of the light shielding film interferes with inspection and photomask position detection. Further, an antireflection layer for reducing reflection of drawing light or exposure light may be provided on the surface of the semi-transparent film or the light shielding film. An antireflection layer may be provided on the back surface of the semi-translucent film.

DESCRIPTION OF SYMBOLS 1 ... Main pattern 2 ... Auxiliary pattern 3 ... Light-shielding part 4 ... Light-transmitting part 5 ... Semi-light-transmitting part 10 ... Transparent substrate 11 ... Semi-light-transmitting film 12 ... Light-shielding film 12p ... Light-shielding film pattern 13 ... 1st photoresist film 13p ... first resist pattern 14 ... second photoresist film 14p ... second resist pattern 15 ... correction film 16 ... replenishment film 17 ... part where the shape of the black defect is adjusted with the supplement film 18 ... part where the film is removed 19 ... white The part where the film was removed near the defect

Claims (26)

A photomask having a light-transmitting portion, a light-shielding portion, and a transfer pattern having a width d1 (μm) and having a translucent portion formed by patterning a light-shielding film and a semi-transparent film on a transparent substrate. A correction method,
Identifying a defect produced in the semi-translucent portion;
A correction film forming step of forming a correction film at the position of the identified defect to form a correction semi-transparent portion having a width d2 (μm);
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A method for correcting a photomask, wherein T2 <T1 and d2> d1.   2. The photomask correction method according to claim 1, wherein d1 and d2 are dimensions that are not resolved by an exposure apparatus that exposes the photomask.   The photomask correction method according to claim 1, wherein the semi-translucent portion is disposed in the vicinity of the translucent portion via the light-shielding portion.   The photomask correction method according to claim 1, wherein T2> T1 and a difference between T1 and T2 is in a range of 2 to 45. 5.   The photomask correction method according to claim 1, wherein d2 <d1 and a difference between d1 and d2 is 0.05 to 2.0.   6. The photo according to claim 1, wherein a light-shielding supplementary film is formed at a position adjacent to the corrected semi-translucent portion before or after the correction film forming step. How to fix the mask.   The semi-translucent part is disposed in the vicinity of the translucent part via the light-shielding part, and changes the light intensity distribution formed on the transferred body by the exposure light that passes through the translucent part, The photomask correction method according to claim 1, wherein an auxiliary pattern for increasing a depth of focus is configured. The transfer pattern to which the correction method is applied is for forming a hole pattern on the transfer target,
A main pattern having a diameter W1 (μm) composed of the translucent portion;
An auxiliary pattern having a width d1 (μm), which is formed of the semi-translucent portion, disposed in the vicinity of the main pattern via the light shielding portion;
8. The photomask according to claim 1, wherein the photomask is in a region excluding the main pattern and the auxiliary pattern, and includes a light-shielding portion surrounding the main pattern and the auxiliary pattern. 9. How to fix.   The photomask correction method according to claim 8, wherein the auxiliary pattern is a polygonal band or a circular band region surrounding the main pattern through the light shielding portion.   A distance between the width center of the main pattern and the width center of the auxiliary pattern is a distance P1, and a distance between the width center of the main pattern and the width center of the correction auxiliary pattern made of the correction semi-transparent portion is P2. 10. The photomask correction method according to claim 8, wherein P1 = P2.   The photomask correction method according to claim 1, wherein the transfer pattern is a pattern for manufacturing a display device.   The manufacturing method of a photomask including the correction method of the photomask of any one of Claims 1-11. In a photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern is:
The translucent part from which the transparent substrate is exposed;
The semi-transparent portion formed by forming a semi-transparent film having a width d1 (μm) on the transparent substrate;
Including the light-shielding portion in a region excluding the light-transmitting portion and the semi-light-transmitting portion;
Including a modified semi-transparent portion formed on the transparent substrate by a modified film having a width d2 (μm), which includes a material different from that of the semi-transmissive film;
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask, wherein T2 <T1 and d2> d1. A photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern has a normal transfer pattern and a corrected transfer pattern,
The normal transfer pattern is:
The translucent part from which the transparent substrate is exposed;
A semitranslucent film formed on the transparent substrate, and the semitranslucent part having a width d1 (μm) disposed in the vicinity of the translucent part via the light shielding part;
Including the light-shielding portion in a region excluding the light-transmitting portion and the semi-light-transmitting portion;
The modified transfer pattern is:
The translucent part from which the transparent substrate is exposed;
A correction film including a material different from the semi-transparent film is formed on the transparent substrate, and is disposed in the vicinity of the translucent part via the light-shielding part or the supplementary light-shielding part. Modified semi-translucent part with
Including the light shielding portion in a region excluding the light transmitting portion and the modified semi-light transmitting portion;
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask, wherein T2 <T1 and d2> d1. A photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern is:
A main pattern having a diameter W1 (μm) composed of the translucent portion;
A semi-transparent film is formed on the transparent substrate, and an auxiliary pattern having a width d1 (μm), which is disposed in the vicinity of the main pattern via the light-shielding portion, and includes the semi-transparent portion;
Including the light-shielding portion in a region excluding the main pattern and auxiliary pattern,
A correction film including a material different from that of the semi-transparent film is formed on the transparent substrate, and a width d2 including the modified semi-transparent part disposed near the main pattern via the light-shielding part. (Μm) correction auxiliary pattern,
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask, wherein T2 <T1 and d2> d1. A photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion on a transparent substrate,
The transfer pattern has a normal transfer pattern and a corrected transfer pattern,
The normal transfer pattern is:
A main pattern having a diameter W1 (μm) composed of the translucent portion;
A semi-transparent film is formed on the transparent substrate, and an auxiliary pattern having a width d1 (μm), which is disposed in the vicinity of the main pattern via the light-shielding portion, and includes the semi-transparent portion;
Including the light-shielding portion in a region excluding the main pattern and the auxiliary pattern;
The modified transfer pattern is:
A main pattern having a diameter W1 (μm) composed of the translucent portion;
A modified semi-transparent portion formed on the transparent substrate by a correction film containing a material different from the semi-translucent film, and disposed near the main pattern via the light-shielding portion or the supplementary light-shielding portion. A correction auxiliary pattern having a width d2 (μm),
In the region excluding the main pattern and the correction auxiliary pattern, including the light shielding portion,
d1 <3.0;
The translucent film has a transmittance T1 (%) with respect to the representative wavelength included in the exposure light, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
The correction film has a transmittance T2 (%) with respect to the representative wavelength, and has a phase shift characteristic that shifts the phase of the light of the representative wavelength by approximately 180 degrees,
T2> T1 and d2 <d1, or
A photomask, wherein T2 <T1 and d2> d1.   When the distance between the width center of the main pattern and the width center of the auxiliary pattern is P1, and the distance between the width center of the main pattern and the width center of the correction auxiliary pattern is P2, P1 = P2. The photomask according to claim 15 or 16, characterized in that   18. The auxiliary pattern according to claim 15, wherein the auxiliary pattern has a shape included in a region of a polygonal band or a circular band surrounding the main pattern via the light shielding portion. Photo mask.   The auxiliary pattern having the width d1 (μm) constitutes a part of an octagonal band area surrounding the periphery of the main pattern via the light shielding portion, and the correction auxiliary pattern is included in the octagonal band area. The photomask according to claim 15, wherein the photomask has a shape. The semi-translucent portion is disposed in the vicinity of the translucent portion via the light-shielding portion, and has a depth of focus with respect to a transfer image formed on the transfer target by the exposure light transmitted through the translucent portion. 20. The photomask according to claim 13, wherein the photomask is an auxiliary pattern for increasing   21. The photomask according to any one of claims 13 to 20, wherein d1 and d2 are dimensions that are not resolved by an exposure apparatus that exposes the photomask.   The photo according to any one of claims 13 to 21, wherein the transfer pattern has a supplementary light-shielding part made of a light-shielding supplementary film at a position adjacent to the modified semi-translucent part. mask.   23. The photomask according to claim 13, wherein T2> T1, and a difference between T1 and T2 is in a range of 2 to 45.   24. The photomask according to any one of claims 13 to 23, wherein d2 <d1 and a difference between d1 and d2 is 0.05 to 2.0.   The photomask according to any one of claims 13 to 24, wherein the transfer pattern is for forming a hole pattern on a transfer target. 26. Using the photomask according to any one of claims 13 to 25, irradiating the transfer pattern with exposure light including any of i-line, h-line, and g-line, and transferring the pattern onto the transfer target. A method for manufacturing a display device, comprising: