KR101364286B1 - Photo mask, pattern transfer method and flat pannel display manufacturing method - Google Patents

Abstract

Provided is a photo mask capable of reliably and precisely transferring a fine pattern. A photomask comprising a transfer pattern having a transmissive portion, a translucent portion on which a translucent film that transmits a part of the exposure light, and a light shielding portion on which a light-shielding film is formed, on the transparent substrate, wherein the translucent film is used to transfer the transfer pattern. It has a transmittance of 2 to 60% and a phase shift effect of 90 degrees or less with respect to the representative wavelength of exposure light to be used, and the transflective part is formed in the width | variety which is not resolved by an exposure apparatus adjacent to the edge of a light shielding part. A photo mask is featured.

Description

Photomask, pattern transfer method and manufacturing method of flat panel display {PHOTO MASK, PATTERN TRANSFER METHOD AND FLAT PANNEL DISPLAY MANUFACTURING METHOD}

The present invention relates to a photomask capable of transferring a fine pattern onto a transfer object, a pattern transfer method, and a manufacturing method of a flat panel display by transferring a transfer pattern.

In the manufacture of a flat panel display typified by a liquid crystal display device, there is a demand to improve image quality by forming a finer pattern. Patent Literature 1 describes a photomask in which a transfer pattern composed of a translucent portion and a transmissive portion corresponding to a line and space is formed.

Japanese Patent Application Laid-Open No. 2009-42753

It has been noticed that the miniaturization of the wiring pattern of the flat panel display is advantageous not only in the improvement of image quality such as the brightness and reaction speed of the flat panel display, but also in terms of energy saving. For this reason, in recent years, new refinement | miniaturization of the wiring pattern of a flat panel display is desired. In connection with this, fine line width precision tends to be expected also in the photo mask used for manufacture of a flat panel display.

However, even if the pattern line width of the so-called binary mask provided with the transfer pattern composed of the light shielding portion and the light transmitting portion is simply miniaturized, the wiring pattern of the flat panel display cannot be miniaturized. Hereinafter, the problem in this case is explained in full detail with reference to FIG.1 (a), (b) and FIG.2 (a)-(e).

Fig.1 (a) is a schematic diagram which shows the light shielding part and the light transmission part which comprise the line and space pattern as a transfer pattern of a binary mask. Here, the line-and-space pattern which consists of a light shield part, consists of the line part which has a line width ML, and the space part which consists of a light transmission part, and has a space width MS is shown. The width of the repeating unit of one pair of light shielding portions and the light transmitting portion is the pitch width P of the line and space pattern.

(B) is a graph which shows the light intensity curve of the transmitted light irradiated on the resist film formed on the to-be-transferred body when the pitch width P of the line and space pattern of FIG. 1 (a) is changed. to be. The vertical axis represents transmittance (%) and the horizontal axis represents position on the mask (µm).

In the transfer pattern of the binary mask shown in Fig. 1A, when the widths ML and MS of the light blocking portion and the light transmitting portion of the line and space pattern are gradually reduced (that is, the pitch width P is reduced), ], As shown in FIG.1 (b), the problem that the light intensity of the transmitted light irradiated to a resist film via a light transmission part falls.

MEANS TO SOLVE THE PROBLEM The present inventors set the conditions shown to Fig.1 (b) from pitch pitch P of line and space pattern = 8 micrometers (line width ML = 4.8 micrometers, space width MS = 3.2 micrometers). The line width ML and the space width MS to the pitch width P, respectively, up to the pitch width P = 4 mu m (line width ML = 2.8 mu m, space width MS = 1.2 mu m). P / 2 + 0.8 (µm) and P / 2-0.8 (µm) were set, and the change in the light intensity of the transmitted light when gradually refined was simulated. As a result, as shown by the light intensity curve of FIG. 1 (b), as the line width of the line and space pattern becomes finer, it can be seen that the peak position of the waveform curve of the light intensity is significantly lowered. The condition setting is numerical aperture NA: 0.08, coherence factor σ: 0.8, exposure light wavelength: g / h / i = 1/1/1, substrate: quartz glass substrate, positive resist (P / R) film Thickness: 1.5 micrometers, positive resist: Novolak-type positive resist, where "g / h / i" shows the intensity ratio of each wavelength of g line | wire, h line | wire, and i line | wire contained in exposure light.

In addition, in the light intensity curve of FIG. 1B, the transmitted light of the line-and-space pattern of pitch width P = 8 micrometers, 7 micrometers, 6 micrometers, and 5 micrometers is positive resist (P / R) on a to-be-transferred body. The cross-sectional shape of the resist pattern formed when irradiating a film | membrane is shown to FIG.2 (a), (b), (c), (d), respectively. In addition, these irradiation light quantity Eop is normalized to 100mJ.

As shown in these figures, the smaller the line width of the line and space pattern, the less the intensity of light passing through the space width MS, and the pitch width P of FIG. In this case, the lines between the resist films are not separated from each other, so that a line-and-space resist pattern cannot be formed. This cannot be used as an etching mask for forming a fine wiring pattern in a later step.

Therefore, as a method of raising the resolution at the time of pattern transfer and performing finer patterning, exposure using the numerical aperture of an exposure machine, the single wavelength, and the short wavelength which were developed as a technique for conventional LSI manufacture are considered. However, when these techniques are applied, enormous investment and technological development are required, and the price can not be matched with the price of the liquid crystal display provided in the market.

By the way, as shown in FIG.2 (d), with the refinement | miniaturization of a pattern, exposure to the phenomenon where the peak position of the waveform curve of light intensity falls remarkably is exposed as a method to compensate for this light quantity shortage. It is conceivable to increase the amount of irradiation light of the device. When the amount of irradiation light increases, the amount of light passing through the space portion increases, and therefore, it is considered that the shape of the resist pattern can be improved, that is, it can be separated into the shape of a line and space pattern. For this reason, it is not practical to change the light source of an exposure apparatus to a large light quantity, and the scanning exposure time at the time of exposure must be greatly increased.

In fact, Fig. 2E shows the case where the resist pattern is well separated by increasing the amount of irradiation light. Here, the irradiation light amount of 1.5 times was required with respect to the irradiation amount used for FIG.2 (a)-(d).

By the way, the said patent document 1 is a photo mask which has a transmissive part and a semi-transmissive part in which the predetermined | prescribed pattern was formed by patterning the semi-transmissive film formed on the transparent substrate, and it exposes on a to-be-transferred body by exposure light which permeate | transmitted the photomask. A photo mask for forming a transfer pattern having a line width of less than 3 μm, comprising: a photo comprising a pattern comprising the light transmitting portion and the semi-transmissive portion having a portion having a line width of at least one of the light transmitting portion or the translucent portion is less than 3 μm Masks are described.

According to the photomask of the said patent document 1, the fall of the light intensity peak position of the light transmission part which occurred when the pattern was refine | miniaturized in FIG.1 (b) is suppressed, and the resist pattern of a line-and-space pattern shape is formed I think it can. This means that the pattern of the translucent film formed on the transparent substrate assists the amount of transmitted light of the entire transfer pattern, including the light transmitting portion, and the amount of necessary light from which the resist can be patterned (that is, the positive resist can be removed by development). It means you could reach.

On the other hand, in recent years, new miniaturization of wiring patterns of flat panel displays is desired, and there is a demand for further improving the stability and precision of patterning.

This invention is made | formed in view of the said problem, and an object of this invention is to provide the photomask, the pattern transfer method, and the manufacturing method of a flat panel display which can reliably and precisely transfer a fine pattern.

(1) In order to achieve the above object, the photomask of the present invention is a transfer pattern having a light transmitting portion, a semi-transmissive portion formed with a translucent film that transmits a part of the exposure light, and a light shielding portion formed with a light shielding film on a transparent substrate. A photomask comprising: the semi-transmissive film has a transmittance of 2 to 60% and a phase shift of 90 ° or less with respect to a representative wavelength of exposure light used for transferring the transfer pattern, wherein the semi-transmissive portion is Adjacent to the edge of the light shielding portion, characterized in that formed in a width that is not resolved by the exposure apparatus.

(2) Preferably, in said photo mask of said (1), the said semi-transmissive part has the 1st semi-transmissive part and the 2nd semi-transmissive part which were formed adjacent each the edge which opposes the said light shielding part, and the said 1st semi-transmissive part The width | variety of a light part and a 2nd semi-transmissive part is a fixed width which is not resolved by an exposure apparatus, respectively, and can be set as the structure which is mutually equal width.

(3) Preferably, in the photomask of the above (1) or (2), the transfer pattern is a line and space pattern, and a line and space on the transfer object having a line width or a space width of less than 3 µm. It can be set as the structure which forms.

(4) Preferably, in the photomask of (1), the semi-transmissive portion is adjacent to the edge of the light-shielding portion and is not resolved by an exposure apparatus in an area surrounded by the continuous light-shielding portion. It can be set as the structure formed in a fixed width.

(5) Preferably, in the photomask of the above (1) or (4), the transfer pattern is a hole pattern, in which a hole having a diameter of less than 3 μm is formed on a transfer object. do.

(6) In order to achieve the above object, the pattern transfer method of the present invention uses the photomask according to any one of the above (1) to (5), and transfers the transfer pattern using the exposure apparatus. It is characterized by transferring to a phase.

(7) In order to achieve the said objective, the manufacturing method of the flat panel display of this invention uses the pattern transfer method of said (6), It is characterized by the above-mentioned.

According to the photomask, the pattern transfer method, and the flat panel display manufacturing method of the present invention, a photomask is obtained which enables the fine pattern to be reliably precisely and precisely transferred onto the transfer object.

Fig.1 (a) is a schematic diagram which shows the line and space pattern of a binary mask, and Fig.1 (b) is a graph which shows the light intensity curve on a to-be-transferred body by the binary mask of Fig.1 (a).
2A to 2D show cross-sectional shapes of resist patterns formed by transmitted light of line and space patterns having a pitch width P of 8 to 5 μm in the light intensity curve of FIG. 1B. Represent each. FIG. 2E shows the cross-sectional shape of the resist pattern when the irradiation light amount of the exposure apparatus is increased 1.5 times with the same pitch width as in FIG. 2D.
FIG. 3A is a schematic cross-sectional view of the photomask of the line-and-space pattern according to the first embodiment of the present invention, and FIG. 3B is a partially enlarged view of FIG. 3A.
4A is a schematic cross-sectional view of the photomask of the line-and-space pattern according to the second embodiment of the present invention, and FIG. 4B is a partially enlarged view of FIG. 4A.
FIG.5 (a)-(g) is a flowchart which shows the manufacturing process of the photomask shown in FIG.
FIG.6 (a)-(g) is a flowchart which shows the manufacturing process of the photomask shown in FIG.
FIG.7 (a)-(f) is a flowchart which shows the other manufacturing process of the photomask shown in FIG.
Fig. 8 shows Comparative Example 1 (binary mask) of a photo mask having a transfer pattern as a line and space pattern. 8A shows a mask image. FIG. 8B shows the light intensity distribution of the transmitted light irradiated onto the transfer object. FIG. 8C shows the peak intensity, contrast, irradiation amount (reference), and resist film reduction (reference) of the light intensity distribution as a simulation result. FIG. 8D shows the shape of a resist pattern formed by the binary mask of Comparative Example 1. FIG.
Fig. 9 shows Reference Example 1 (transmission auxiliary mask 1) of a photo mask having a transfer pattern as a line and space pattern. 9A illustrates a mask image. FIG. 9B shows the light intensity distribution of the transmitted light irradiated on the resist film formed on the transfer object. FIG. 9C shows the peak intensity, contrast, irradiation amount, and resist film reduction of the light intensity distribution as a result of the simulation. FIG. 9D shows the shape of the resist pattern formed by the transmission assisting mask 1 of Reference Example 1. FIG.
FIG. 10 shows Example 1 (transmission auxiliary mask 2) of a photomask in which the transfer pattern is a line and space pattern. 10A illustrates a mask image. FIG. 10B shows the light intensity distribution of the transmitted light irradiated on the resist film formed on the transfer object. 10C shows the peak intensity, contrast, irradiation amount, and resist film reduction of the light intensity distribution as a result of the simulation. FIG. 10D shows the shape of a resist pattern formed by the transmission assisting mask 2 of Example 1. FIG.
11A to 11C show Comparative Examples 2 (binary masks), Reference Examples 2 (transmission aiding mask 3), and Example 2 (transmission aiding mask 4) of a photomask having a transfer pattern as a hole pattern, respectively. Shows a mask image. (D) is a simulation evaluation item and its explanatory drawing.
FIG. 12 is a comparison of simulation results of Comparative Example 2, Reference Example 2, and Example 2 of FIG. 11, FIG. 12A shows the irradiation light amount, FIG. 12B shows the resist inclination angle, and FIG. ) Is a graph showing a decrease in resist film.

The photomask of this invention is equipped with the transfer pattern which has a light transmission part, the transflective part in which the transflective film which permeate | transmitted a part of exposure light was formed, and the light shielding part in which the light shielding film was formed on the transparent substrate. The semi-transmissive film has a transmittance of 2 to 60% and a phase shift of 90 ° or less with respect to the representative wavelength of the exposure light used for the transfer of the transfer pattern, and the semi-transmissive portion is adjacent to the edge of the light shielding portion, It is characterized by being formed in a width which is not resolved by the exposure apparatus. Such embodiment of the photomask of this invention is illustrated in FIGS. 3-7 (cross section), FIG. 10 (a), and FIG. 11 (c) (viewed from the top).

<Embodiment of Photo Mask>

3 (a) and 3 (b) show a cross-sectional schematic diagram and a partial enlarged view of a transfer pattern included in the photomask 1 for forming a line and space pattern according to the first embodiment of the present invention. . 4A and 4B are cross-sectional schematic diagrams and partial enlarged views of the transfer pattern of the photomask 2 for forming a line-and-space pattern according to the second embodiment of the present invention. . The mask image which looked at these photomasks 1 and 2 on the plane is shown to FIG. 10 (a). Moreover, the mask image which looked at the photomask 3 for hole pattern formation which concerns on 3rd Embodiment of this invention from the plane is shown in FIG.11 (c).

In addition, in this specification, since the line-and-space pattern is formed on a to-be-transfer body, the transfer pattern which a photomask has is also called a line-and-space pattern, and since the hole pattern is formed on a to-be-transfer body, the transfer which a photomask has The pattern is also referred to as a hole pattern. Here, the line pattern in the line-and-space pattern as the transfer pattern is a portion other than the light-transmitting portion (light-shielding portion and semi-transmissive portion), and the space pattern refers to the light-transmitting portion. In addition, the hole pattern in a transcription pattern is called a light transmission part.

In the embodiment described below, the photo masks 1 and 2 of the line and space pattern will be mainly described as specific examples.

In the photomasks 1 and 2 having the line and space pattern according to the present embodiment, the semi-transmissive film 20 formed on the transparent substrate 10 and the light-shielding film (hereinafter referred to as light shielding film) 30 are patterned. It is formed. The difference between the photomasks 1 and 2 is that the stacking order of the translucent film 20 and the light shielding film 30 is reversed.

First, the transparent substrate 10, the semitransmissive film 20, and the light shielding film 30 constituting the photomasks 1 and 2 of the present embodiment will be described.

As the transparent substrate 10 constituting the photomasks 1 and 2 of the present embodiment, a quartz glass substrate having a polished surface is used. The size of the transparent substrate 10 is not particularly limited and is appropriately selected depending on the substrate (for example, a substrate for flat panel display) exposed using the photo masks 1 and 2. As such a transparent substrate 10, for example, a rectangular substrate having one side of 300 mm or more is used.

As shown in FIGS. 3A and 4A, the photomasks 1 and 2 of the present embodiment include a line L formed of the translucent portion 21 and the light shielding portion 31. And a space S made of a light transmitting portion.

In the light transmitting portion that transmits the exposure light, the transparent substrate 10 is preferably exposed. The transflective film 21 is formed by forming the transflective film 20 on the transparent substrate 10, The translucent film 20 may be a single layer, or may be formed by lamination of a plurality of layers. This semi-transmissive film 20 has a transmittance of 2 to 60% with respect to light having a representative wavelength included in the exposure light, and has a phase shift operation of 90 ° or less with respect to the representative wavelength. The light shielding portion of FIG. 3A is formed by stacking a light shielding film on the semi-transmissive film, and the light shielding portion of FIG.

Among the optical properties included in the translucent film, the phase shift action of 90 ° or less is preferably 90 ° or less in excess of 0 ° with respect to the representative wavelength of the exposure light. The semi-transmissive portion 21 in this case has a function of assisting the amount of transmitted light of the transmissive portion, rather than exerting a so-called phase shift action to enhance the contrast. Therefore, the transflective film 20 can be considered to be a transmission auxiliary film, and the translucent part 21 can be considered to be a transmission auxiliary part.

For example, if the amount of phase shift of the semi-transmissive film 20 is close to 180 °, phase reversal is performed at the boundary between the translucent portion 21 (that is, the first and second translucent portions 21A, 21B in the figure) and the translucent portion. It is discovered by the present inventors that one diffracted light interferes with each other and the auxiliary function of the amount of transmitted light, which is one of the characteristics of the present invention, is rather hindered.

If the amount of phase shift is excessively small, selection of the material constituting the semi-transmissive film 20 is not easy. If the amount of phase shift is excessively large, interference of light in the reverse phase occurs as described above, and transmission is performed. It is preferable to select the material and the film thickness of the translucent film 20 in consideration of impairing the auxiliary effect of the amount of light. The range of the phase shift amount of the translucent film 20 exceeds 0 degrees and is 90 degrees or less [this is radian notation, (2n-1 / 2) pi-(2n + 1/2) pi (n is an integer ) Means, preferably 5 to 60 °, more preferably 5 to 45 °.

The transmittance of the semitransmissive membrane 20 is the transmittance of the semitransmissive membrane 20 when the transmittance at the representative wavelength of the transparent substrate 10 is 100%. If the transmittance of the semi-transmissive membrane 20 is too small, the auxiliary function of the amount of transmitted light of the present invention cannot be sufficiently exhibited. If the transmittance is excessively large, difficulty of mask manufacture such as film thickness control of the semi-transmissive membrane is high, and thus semi-transmissive The transmittance of the membrane 20 is in the range of 2 to 60%. Moreover, the preferable transmittance | permeability range of the translucent film 20 is 10 to 50%, More preferably, it is 10 to 35%, More preferably, it is 15 to 30%.

Here, as the representative wavelength of the exposure light, when the exposure light includes a plurality of wavelengths (for example, when using a light source including i-line, h-line, and g-line), one of these wavelengths may be used. Can be. For example, the i-line may be a representative wavelength. As for any of these wavelengths, it is more preferable to satisfy the above numerical range.

The light shielding film 30 may not necessarily have complete light shielding property with respect to exposure light. When the light shielding portion 31 is formed (by a single layer of the light shielding film 30 only or a stack of the light shielding film 30 and the translucent film 20), the exposure light transmittance of this portion is the exposure light of the semi-transmissive portion 21. It may be smaller than the transmittance. As for the preferable exposure light transmittance of the light shielding portion 31 in the case of lamination, when the light shielding film 30 is laminated with the translucent film 20, the optical density OD (Optical Density) with respect to the exposure light is 3 or more. Preferably, More preferably, OD is three or more independently of a light shielding film.

In addition, although the light shielding part 31 may be formed by the light shielding film 30 alone, it is preferable that it is comprised by lamination | stacking of the translucent film 20 and the light shielding film 30 as shown in FIG. In this case, there is no restriction on the stacking order.

About the state in which the semi-transmissive part 21 in this embodiment is formed adjacent to the edge of the light shielding part 31, the case of a line and space pattern is shown in FIG.10 (a), the case of a hole pattern. It shows in 11 (c). As shown in these figures, in any case, the transflective portion 21 is adjacent to the edge of the light shielding portion 31 and is also adjacent to the light transmitting portion. That is, the transflective portion 21 is located between the light shielding portion 31 and the light transmitting portion. In the present embodiment, the translucent portion 21 is formed to have a constant width.

Hereinafter, the first and second translucent portions 21A and 21B will be described in detail with reference to FIGS. 3, 4 and 10, taking the case of the line and space pattern as a specific example.

The first and second semi-transmissive portions 21A and 21B shown in FIG. 10A are adjacent to the edges on both sides of the light-shielding portion 31, respectively, and are formed in a width not resolved by the exposure apparatus.

In general, in the LCD exposure apparatus (described later), the resolution limit is set to about 3 µm. The width | variety of the 1st and 2nd translucent part 21A, 21B of this embodiment is the dimension of less than this 3 micrometers. Therefore, it becomes the width | variety which is not resolved on a to-be-transferred body at the time of exposure. That is, when the exposure pattern is irradiated with the exposure light under a predetermined exposure condition, in the light intensity curve of the transmitted light received by the transfer object, in the portions corresponding to the first and second semi-transmissive portions 21A and 21B, An independent (non-continuous) pattern shape is not observed, and a curve in which the peak of the light intensity by the light transmitting portion and the bottom of the light intensity by the light blocking portion 31 is smoothly continued is shown. This state is shown in FIG.

Here, the first and second semi-transmissive portions 21A and 21B of constant width, which are formed adjacent to both edges of the line of the light shielding portion 31 shown in FIG. 10A, are in the light intensity curve. It does not appear as an independent (discontinuous) pattern, and serves to assist the amount of light to the peak portion of the light transmitting portion. As a result, in one side of the resist pattern to be formed, the amount of remaining film is monotonically increasing or monotonically decreasing.

In addition, about the light intensity curve and the resist pattern shape which show in FIG. 8 thru | or 10 are all obtained by optical simulation. As a simulation condition, it sets in consideration of the optical conditions of the exposure apparatus used for pattern transfer. Here, the exposure apparatus used for pattern transfer can be said to be a standard exposure apparatus for LCD (Liquid Crystal Display). In this case, for example, the numerical aperture NA can be in the range of 0.06 to 0.10 and the coherence factor sigma in the range of 0.5 to 1.0. In general, such an exposure apparatus has a resolution limit of about 3 μm.

Of course, the present invention can also be applied at the time of pattern transfer using a wider range of exposure apparatus. For example, the numerical aperture NA can be in the range of 0.06 to 0.14, or 0.06 to 0.15. Demand has also arisen in the high resolution exposure apparatus which numerical aperture NA exceeds 0.08, and it is applicable also to these.

Such an exposure apparatus includes i-line, h-line, and g-line as the light source, and can use irradiated light containing all of them (hereinafter referred to as "broad light" because it is a broad light source for a single light source). In this case, the representative wavelength may be any of i-line, h-line, and g-line as described above. In the simulation, for the sake of simplicity, these intensity ratios may be 1: 1: 1, or may be ratios in consideration of the intensity ratio of the exposure apparatus actually used.

Returning to Fig. 10, as a preferred embodiment of the photomask of the present invention, the semi-transmissive portion 21 is formed of a first semi-transmissive portion 21A and a second semi-transmissive portion each formed adjacent to the opposing edges of the light-shielding portion 31. 21B). The widths of the first semi-transmissive portion 21A and the second semi-transmissive portion 21B are constant widths that are not resolved by the exposure apparatus, respectively, and can be equal to each other.

Such a photo mask is, for example, as shown in Figs. 3A and 3B,

The light-transmitting part (refer to the symbol S in the figure), the semi-transmissive part 20, and the light-shielding part 30 formed by patterning the semi-transmissive film 20 and the light-shielding film 30 respectively laminated on the transparent substrate 10 are included. Equipped with a transfer pattern,

The transparent part 10 exposes the transparent substrate,

The light shielding portion 31 is formed on the transparent substrate 10 by laminating the light shielding film 30 on the translucent film 20,

Semi-transmissive portion 21 is formed on the transparent substrate 10, the translucent film 20 is formed,

The semi-transmissive portion 21 is a first semi-transmissive portion 21A formed adjacent to the first edge of the light-shielding portion 31 and a second semi-transmissive portion formed adjacent to the second edge opposite to the first edge of the light-shielding portion 31. Including a miner 21B,

The first and second semi-transmissive portions 21A and 21B are constant widths which are not resolved by the exposure apparatus, respectively, and have a width equal to each other.

Said photo mask 1 can also be expressed as follows.

A photo mask having a transfer pattern comprising a light transmitting portion, a semi-transmissive portion 20, and a light blocking portion 30 formed by patterning the semi-transmissive film 20 and the light-shielding film 30 on the transparent substrate 10, respectively. 1),

The transparent part 10 exposes the transparent substrate,

The light shielding portion 31 is formed on the transparent substrate 10 by laminating the light shielding film 30 on the translucent film 20,

Semi-transmissive portion 21 is formed by forming a translucent film 20 on the transparent substrate 10,

The semi-transmissive portion 21 includes a first semi-transmissive portion 21A formed adjacent to the first edge of the transmissive portion, and a second semi-transparent portion 21B formed adjacent to the second edge opposite to the first edge of the transmissive portion,

The first and second semi-transmissive portions 21A and 21B are constant widths which are not resolved by the exposure apparatus, respectively, and have a width equal to each other.

That is, the first and second semi-transmissive portions 21A and 21B are adjacent to the edge of the light shielding portion 31 and adjacent to the edge of the light-transmitting portion.

The first semi-transmissive portion 21A and the second semi-transmissive portion 21B are formed to face the light-shielding portion 31 symmetrically and have a width equal to each other. Here, it is preferable that the width | variety equivalent to each other is the difference of the line width of the 2nd semi-transmissive part 21B with respect to the line width of the 1st semi-transmissive part 21A within 0.1 micrometer. More preferably, it is within 0.05 micrometers. In addition, in the whole transfer pattern with which the said photomask 1 is equipped, it is preferable to make the line width precision of the translucent part 21 into the said range. By doing in this way, the auxiliary action | action of the amount of transmitted light given to a light transmission part becomes symmetrical, and the line width precision of the pattern formed on a to-be-transferred body can be precisely and precisely controlled.

Here, in the photomask of this invention, when the width | variety of a light transmission part becomes 3 micrometers or less, the auxiliary effect of the amount of transmitted light of this invention is remarkable for the following reason. As the dimension (width) of the light transmitting portion decreases, the influence of diffraction increases and the peak of the light intensity curve passing through the light transmitting portion decreases, so that the amount of light tends to be insufficient in order to reach the resist film and to expose the resist. This is because the photomask of the present invention solves the problem. When the width of the light transmitting portion is 2 m or less, the auxiliary effect of the amount of transmitted light is greater.

As shown in Examples described later, the transflective portion of the present invention has a function of raising the peak of the light intensity curve passing through the transmissive portion as compared with the case where the translucent portion was part of the light shielding portion (when it was a binary mask). Have For this reason, the photomask of this invention is especially advantageous when forming the space pattern of less than 3 micrometers on a to-be-transferred body.

In addition, when the width | variety of the semi-transmissive part which has the auxiliary function of the transmitted light quantity with respect to the above-mentioned light transmitting part is too large, the fall of the side shape of the resist pattern formed will become remarkable, It is preferable that it is 1 micrometer or less. As a preferable range of the width | variety of a translucent part, it is 0.1-1 micrometer. In the case where the first semi-transmissive portion 21A and the second semi-transmissive portion 21B are formed adjacent to the opposite edges of the light shielding portion 31 as in the present embodiment, the first semi-transmissive portion 21A and the first agent It is preferable that the width | variety of 2 semi-transmissive part 21B is 1 micrometer or less (0.1-1 micrometer).

3 and 4 are examples of the case where the line and space pattern is used as the transfer pattern, but there is no restriction on the shape or use of the transfer pattern in the photomask of the present invention. It may be a line-and-space pattern, or may be applied to a hole pattern as shown in Fig. 11C. Also in the case of a hole pattern, the width | variety of a translucent part can be set similarly to the above. In addition, you may use this invention for the transfer patterns other than the pattern illustrated by this specification and drawing.

Moreover, the photomask of this invention has freedom also in the laminated structure, and may have the light shielding part 31 which laminated | stacked the light shielding film 30 on the transflective film 20 as shown in FIG. As shown in FIG. 4, you may have the light shielding part 31 which laminated | stacked the translucent film 20 on the light shielding film 30. As shown in FIG. These are related to the manufacturing method of the photomask of this embodiment demonstrated below.

Moreover, the photomask of this invention is used advantageously for the use by which the transfer image formed on a to-be-transferred body becomes two tone. That is, it has a different function from the multi-gradation photo mask of three or more gradations for obtaining a so-called multi-step resist residual film value.

<Embodiment of the manufacturing method of the photo mask>

Next, embodiment of the manufacturing method of the photomask of this invention is described, referring FIG. 5, FIG. 6, and FIG.

[Manufacturing Method 1]

The manufacturing process (manufacturing method 1) of the photomask 1 shown in FIG. 3 mentioned above is demonstrated along FIG. 5 (a)-(g).

First, the photo mask blank shown to Fig.5 (a) is prepared. The photomask blank is formed by forming a semi-transmissive film 20 and a light shielding film 30 on the transparent substrate 10 in this order, and forming a positive photoresist film 40 on the light shielding film 30.

Then, as shown in Fig. 5A, a pattern for forming the light shielding portion 31 shown in Fig. 3 is drawn on the photoresist film 40 using a drawing device not shown.

Subsequently, as shown in FIG. 5B, the photoresist film 40 is developed to form a resist pattern 41.

As shown in FIG. 5C, the light shielding film 30 is etched using the resist pattern 41 formed through the first development step as a mask. As a result, the light shielding portion 31 is formed. In addition, the etching of the light shielding film 30 may be dry etching or wet etching. A known etchant can be used.

Subsequently, after peeling the resist pattern 41 shown to FIG. 5C, as shown to FIG. 5D, the whole surface of the translucent film 20 in which the light shielding part 31 was formed is shown. Then, the photoresist film 50 is formed again, and the pattern for forming the translucent part 21 shown in FIG. 3 by the drawing machine is drawn.

As shown in FIG. 5E, the photoresist film 50 is developed to form a resist pattern 51.

Next, as shown in FIG. 5F, the semi-transmissive film 20 is etched using the resist pattern 51 formed through the second development process as a mask as a mask. To form. As described above, the etching of the semitransmissive film 20 can also be performed by dry or wet etching using a known etchant.

Thereafter, by removing the resist pattern 51 shown in FIG. 5F, the photomask 1 having the structure shown in FIG. 5G is completed.

[Change Example of Manufacturing Method 1]

In the manufacturing method 1 mentioned above, you may change as follows i) -vi).

i) A photo mask blank similar to that described in FIG. 5A is prepared, and a pattern for forming the translucent portion 21 is drawn in the photoresist film.

ii) The photoresist film of i) is developed and a resist pattern is formed.

iii) A light shielding film is etched using the resist pattern formed in said ii) as a mask, and then a semi-transmissive film is etched.

iv) The resist pattern is peeled off, and the photoresist film is formed on the whole surface again, and the pattern for forming a light shielding part is drawn.

v) The photoresist film of iv) is developed to form a resist pattern.

vi) A light shielding film is etched using the resist pattern of said v) as a mask. Thereby, the light shielding part of predetermined width | variety is formed, and the photomask 1 of the structure shown to Fig.5G is completed.

In addition, unless the function of the photomask of this invention is lost, the case where other films other than a translucent film and a light shielding film are formed is not excluded. For example, when the etching selectivity of the translucent film and the light shielding film is not sufficient, that is, when the lower layer film does not have sufficient resistance to the etchant of the upper layer film, even if the etching stopper layer is formed between the lower layer film and the upper layer film, Does not matter. Preferably, the light shielding film and the translucent film are preferably made of a film material having respective etching selectivity.

[Manufacturing Method 2]

A manufacturing process (manufacturing method 2) of the photomask 2 shown in FIG. 4 mentioned above is demonstrated along FIG. 6 (a)-(g).

First, the photo mask blank shown to Fig.6 (a) is prepared. This is to form a light shielding film 30 on the transparent substrate 10 and to form a photoresist film 40 on the light shielding film 30.

Then, as shown in Fig. 6A, a pattern for forming the light shielding portion 31 shown in Fig. 4 is drawn on the photoresist film 40 using a drawing device not shown.

Subsequently, as shown in FIG. 6B, the photoresist film 40 which has undergone the first drawing process is developed to form a resist pattern 41.

Subsequently, as shown in FIG. 6C, the light shielding film 30 is etched using the resist pattern 41 as a mask. As a result, the light shielding portion 31 is formed on the transparent substrate 10.

Thereafter, after removing the resist pattern 41 shown in FIG. 6C, as shown in FIG. 6D, the light blocking part 31 formed through the etching process of the light shielding film is included. The semi-transmissive film 20 is formed into a film on the whole surface of the transparent substrate 10 to be described.

Next, as shown in Fig. 6E, the photoresist film 50 is again formed on the translucent film 20, and then a pattern for forming the translucent portion 21 shown in Fig. 4 is formed. The photoresist film 50 is drawn.

6F, the photoresist film 50 which passed through the said 2nd drawing process is developed, and the resist pattern 51 is formed. Thereafter, the semi-transmissive film 20 is etched using this resist pattern 51 as a mask. Thereby, the translucent part 21 (FIG. 6G) is formed.

Thereafter, the resist pattern 51 shown in FIG. 6F is peeled off, thereby completing the photomask 2 having the configuration shown in FIG. 6G.

In the case of the manufacturing method 2 mentioned above, since etching selectivity is not necessary especially between the translucent film 20 and the light shielding film 30, there exists an advantage that the freedom of material selection is wide.

[Manufacturing Method 3]

Another manufacturing process 3 of the photomask 1 shown in FIG. 3 is demonstrated along FIG.7 (a)-(f).

First, the photo mask blank shown to Fig.7 (a) is prepared. Here, the semi-transmissive film 20 and the light shielding film 30 are formed in this order on the transparent substrate 10, and the photoresist film 60 is formed on the light shielding film 30.

Then, as shown in Fig. 7A, a pattern for forming the translucent portion 21 shown in Fig. 3 is drawn on the photoresist film 60 using a drawing device not shown.

Next, as shown in FIG. 7B, the photoresist film 60 having undergone the above drawing process is developed to form a resist pattern 61.

As shown in FIG. 7C, the light shielding film 30 is etched with the light shielding film etchant using the resist pattern 61 as a mask.

As shown in FIG. 7D, the semitransmissive film 20 is subsequently etched with an etchant for translucent film. Thereby, the transflective part 21 of predetermined width | variety is formed.

Next, as shown in FIG. 7E, the light shielding film 30 is side etched with the wet etchant for light shielding film using the resist pattern 61 as a mask. As a result, the light shielding portion 31 having a predetermined width is formed.

Thereafter, by removing the resist pattern 61 shown in FIG. 7E, the photomask 1 having the structure shown in FIG. 7F is completed.

In the manufacturing method 3 mentioned above, the semi-transmissive film 20 and the light shielding film 30 use the material which has etching selectivity mutually. In addition, in the etching process of the 2nd light shielding film shown to Fig.7 (e), since side etching by an isotropic etching is used, it is suitable to apply wet etching.

In the above-mentioned manufacturing methods 1 to 3, when the manufacturing method 3 is used, the line width accuracy of the semi-transmissive portion 21 is obtained highest, which is a preferable method. According to this manufacturing method 3, since a drawing process can be performed once, compared with the manufacturing methods 1 and 2 which require two drawing, deterioration of the pattern precision by alignment misalignment can be avoided.

<Pattern Transfer Method Using Photo Mask>

This invention also includes the pattern transfer method using the photomask of this invention mentioned above. That is, as described above, the photomask of the present invention has an auxiliary effect of the amount of transmitted light. Therefore, when the transfer pattern is transferred onto the transfer object using the photomask of the present invention, it is possible to transfer the fine pattern without increasing (or decreasing) the amount of irradiation light of the exposure apparatus, thereby saving energy or exposure time. Shortening, resulting in a significant advantage in the improvement of production efficiency.

For example, the photomask of the present invention is useful for forming a line and space having a line width and / or a space width of less than 3 µm on a transfer object. For example, it is used for various uses in the area | region of a flat panel display, such as a transparent electrode pattern of a liquid crystal display device. In the formation of such a line-and-space pattern, since the difficulty is high when the line width is less than 3 µm, the effect of the present invention is remarkable.

In addition, the photomask of this invention can be made to have the transfer pattern for hole formation. In this case, it is useful as a pattern which forms the hole whose diameter is less than 3 micrometers. For example, it may be used for a contact hole of a thin film transistor (TFT).

In the photomask of the present invention, the material of the translucent film is a Cr compound (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc.) of Cr, Si compound (SiO ₂ , SOG), metal silicide compound (TaSi, MoSi) , WSi or their nitrides, oxynitrides, and the like).

As the material of the light shielding film, in addition to Cr or Cr compounds (oxides of oxides, nitrides, carbides, oxynitrides, oxynitrides, etc.), Ta, W or their compounds (including the metal silicides) and the like can be given.

When etching selectivity is needed between a light shielding film and a semi-transmissive film, Cr or a Cr compound may be used for a light shielding film, and a Si compound or a metal silicide compound may be used for a semi-transmissive film. Alternatively, a Cr compound may be used for the translucent film and a metal silicide compound may be used for the light shielding film.

&Lt; Example 1 >

Hereinafter, Comparative Example 1, Reference Example 1, and Example 1 of the photomask having the transfer pattern as a line and space pattern will be described with reference to FIGS. 8 to 10.

Comparative Example 1

8 shows a comparative example 1 of a photomask (binary mask) using a line-and-space pattern formed by patterning a light shielding film (OD3 or more) as a transfer pattern. Here, FIG. 8A shows the transfer pattern used in Comparative Example 1. FIG. FIG. 8B shows the light intensity distribution of the transmitted light irradiated on the resist film formed on the transfer object when exposed to this transfer pattern. FIG.8 (c) shows each evaluation item value obtained by this simulation. FIG. 8D shows a resist pattern formed by the binary mask of Comparative Example 1. FIG.

In FIG. 8A, the binary mask of Comparative Example 1 is a photomask in which a line-and-space pattern composed of a light transmitting portion and a light blocking portion 31 is a transfer pattern on a transparent substrate (not shown). In the comparative example 1, the pitch width P of a line and space pattern is set to 7 micrometers (line width ML = 3.5 micrometers, space width MS = 3.5 micrometers).

The simulation optical conditions applied here are a broad light including i-line, h-line, and g-line, with a numerical aperture NA of the exposure apparatus of 0.085, coherence factor σ of 0.9, intensity of irradiation light source, g-line: h line | wire: i line | wire = 1: 0.8: 0.95. As a resist, the novolak-type positive type was used and the initial film thickness was 1.5 micrometers.

In addition, the contrast as an evaluation item is a maximum value of Imax and a minimum value of Imin in FIG. 8B.

Contrast = (Imax-Imin) / (Imax + Imin)

It was made.

In addition, these were common also applied to the transmission auxiliary mask 1 (Reference Example 1, FIG. 9) and transmission auxiliary mask 2 (Example 1, FIG. 10) described below.

Here, the amount of irradiation light required to form a line-and-space pattern having a line width of 2.9 μm (pitch width P is 7 μm) on the transfer member is determined as the irradiation light amount Eop in Comparative Example 1 (binary mask). Based on the irradiation light quantity, Reference Example 1 and Example 1 were evaluated. In addition, about the item of resist film reduction, the amount of reduction | decrease with respect to the resist film thickness (initial film thickness 1.5 micrometers) formed on the to-be-transferred body is meant, and it is the reference example 1 and implementation based on the comparative example 1 as mentioned above. Example 1 is being evaluated.

First, the simulation result of the comparative example 1 (binary mask) is demonstrated by FIG.8 (b), (c), and (d). The transmitted light which has transmitted the transfer pattern of the binary mask of the comparative example 1 is irradiated on the resist film formed on the to-be-transferred body, and the light intensity distribution as shown to FIG. 8 (b) is formed on this resist film. The shape of the resist pattern formed by such a light intensity distribution is shown to FIG. 8 (d).

As shown in FIG. 8C, the peak intensity of the light intensity distribution of Comparative Example 1 was 0.82 and the contrast was 0.92.

[Referential Example 1]

FIG. 9 shows Reference Example 1 (transmission auxiliary mask 1) of a photomask in which a line-and-space pattern formed by patterning a translucent film as a transfer pattern. As in Comparative Example 1, FIG. 9A illustrates a transfer pattern, and FIG. 9B illustrates a light intensity distribution of transmitted light irradiated on a resist film formed on a transfer object. 9 (c) shows each evaluation item value by this simulation. FIG. 9D shows the shape of the resist pattern formed by the transmission assisting mask 1 of Reference Example 1. FIG.

In FIG. 9A, the transmission auxiliary mask 1 of Reference Example 1 is a photo mask in which a line-and-space pattern composed of a light transmitting portion and a semi-transmissive portion 21 is a transfer pattern on a transparent substrate (not shown). As for the semi-transmissive film which forms the semi-transmissive part 21 of the reference example 1, the exposure light transmittance with respect to the representative wavelength i line is 8%, and the amount of phase shift is 45 degrees. The pitch width P of the line and space pattern of Reference Example 1 is the same as that of Comparative Example 1 above. Simulation optical conditions of the reference example 1 are also the same as the said comparative example 1.

The simulation result of the reference example 1 is shown to FIG. 9 (b), (c) and (d). The transmitted light transmitted through the transfer pattern of the transmission auxiliary mask 1 of the reference example 1 is irradiated on the resist film formed on the to-be-transferred body, and the light intensity distribution as shown in FIG. 9 (b) is formed on this resist film. . The shape of the resist pattern formed by such a light intensity distribution is shown to FIG. 9 (d).

As shown in FIG. 9C, in the transmissive auxiliary mask 1 of Reference Example 1, the irradiation light amount (DOSE amount Eop) was reduced by about 25% compared with Comparative Example 1 above. That is, it became possible to shorten the time of the scanning exposure by an exposure apparatus by 25%.

On the other hand, in the light intensity distribution of the exposure light which a to-be-transmitted body receives, contrast was 0.74 and it became slightly small compared with the said comparative example 1. In connection with this, the shape of the formed resist pattern (refer to FIG. 9 (d)) has a smaller inclination angle (an inclination angle at the time of maximizing 90 ° with respect to the horizontal plane) than that of Comparative Example 1 above. . This means that the variation in the line width resulting from the process variation in the machining process of the transfer object increases.

Example 1

10 shows Example 1 (transmission auxiliary mask 2) of a photomask having a transfer pattern according to the present invention. As in Comparative Example 1, FIG. 10A shows a transfer pattern, and FIG. 10B shows a light intensity distribution of transmitted light irradiated on a resist film formed on a transfer object. 10 (c) shows each evaluation item by this simulation. FIG. 10D shows the shape of the resist pattern formed by the transmission assisting mask 2 of Example 1. FIG.

In FIG. 10A, the transmission assisting mask 2 of Example 1 is a photo mask having the above-described line and space pattern according to the present invention as a transfer pattern. The transmission assisting mask 2 has the same pitch width P as that of Comparative Example 1, but the line pattern is adjacent to both edges of the light shielding portion 31 and the first and second semi-transmissive portions 21A and 21B (transmittance). 20% and a semi-transmissive film having a phase difference of 45 °) are formed. The line pattern of the transmission auxiliary mask 2 has the structure which formed the 1st and 2nd semi-transmissive parts 21A and 21B of 1.0 micrometer, respectively, adjacent to the both edges of the light shielding part 31 of 1.5 micrometers. The simulation optical conditions of Example 1 are the same as those of Comparative Example 1 above.

The simulation result of Example 1 is shown to FIG. 10 (b), (c) and (d). The transmitted light transmitted through the transfer pattern of the transmission assisting mask 2 of Example 1 is irradiated onto the resist film formed on the transfer object, and the light intensity distribution as shown in Fig. 10B is formed on the resist film. do. The shape of the resist pattern formed by such a light intensity distribution is shown in FIG.10 (d).

As shown in FIG. 10C, in the transmission assisting mask 2 of Example 1, the amount of irradiation light (DOSE amount Eop) required to form a resist pattern is similar to that of Comparative Example 1 in the same manner as in Reference Example 1. In comparison, it was about 26% cut. In addition, in the transmission auxiliary mask 2 of Example 1, compared with the said Comparative Example 1, the fall of contrast in a light intensity distribution is hardly seen.

Here, as shown in Fig. 10D, in the transmissive auxiliary mask 2 of Example 1, the inclination angle of the resist pattern side surface is larger and improved than that of Reference Example 1 above. Improvement of the inclination angle of the side surface of the resist pattern greatly contributes to the stability of the etching process of the transfer object, which is performed as a mask of the resist pattern. This is because fluctuations in the pattern line width formed by etching become small due to fluctuations in etching time and etching rate.

In addition, in Example 1, compared with the binary mask of the said Comparative Example 1 which does not have a transmission auxiliary pattern as a photo mask which has a pattern for transcription of the same design as the photomask of Example 1, about 26% of the amount of irradiation light is reduced Is shown. By the effect of reducing the amount of irradiation light, the photomask of the present invention is a photomask (conventional binary mask) in the case where the transmissive auxiliary pattern portion of the semitransmissive film is replaced with a light shielding film and formed integrally with the light shielding portion. In comparison, it can be set as the photomask which exposes by 10% or more of irradiation light quantity. More preferably, it can be set as the photo mask which exposes by 20% or more of irradiation light quantity.

By the simulation result of Example 1 mentioned above, the effect of the photomask of this invention can be demonstrated as follows. That is, the photomask of this invention forms the transmission assistance pattern which has a function for assisting the transmitted light quantity of a light transmission part near the edge of a light shielding part. With this configuration, in the light intensity curve of the transmitted light transmitted through the photomask as shown in Fig. 10B, the amount of transmission at the peak position of the curve corresponding to the center of the light transmitting portion can be made sufficiently high. In addition, the bottom position of the curve corresponding to the center of the light shielding portion is suppressed from rising. For this reason, the inclination of a light intensity curve becomes large and as a result, the inclination angle of the side surface shape of the resist pattern formed on the to-be-transferred body as shown in FIG.10 (d) can be enlarged (about a photo mask surface). , Closer to vertical). It is a matter of course that such improvement of the resist pattern shape is recognized as an improvement of the pattern profile.

<Example 2>

Hereinafter, the simulation performed about the comparative example 2, the reference example 2, and the Example 2 of the photomask which used the transfer pattern as the hole pattern is demonstrated, referring FIG. 11 and FIG.

<Configuration of Each Photo Mask of Comparative Example 2, Reference Example 2, and Example 2>

First, the structure of each photomask of the comparative example 2, the reference example 2, and the Example 2 is demonstrated, referring FIG. 11 (a)-(c). 11A to 11C show Comparative Examples 2 (binary masks), Reference Examples 2 (transmission auxiliary masks 3), and Example 2 (transmission auxiliary masks 4) of photo masks using the transfer pattern as a hole pattern, respectively. ) Represents a mask image.

In FIG. 11A, the photomask of Comparative Example 2 forms a light shielding portion 31 made of a light shielding film (OD 3 or more) on a transparent substrate (not shown), and transmits light in the center of the light shielding portion 31. It is a binary mask (symbol 3 in drawing) which formed the non-square square hole H. As shown in FIG.

In FIG. 11B, the photomask of Reference Example 2 is a transfer pattern having the same design as that of Comparative Example 2, and the light-shielding portion 31 of Comparative Example 2 is formed of a semi-transmissive film ( 21 is a transmissive auxiliary mask 3 (symbol 4 in the drawing). In this semi-transmissive film, the exposure light transmittance with respect to the representative wavelength i line is 7%, and the amount of phase shift is 45 degrees.

In FIG. 11C, the photomask according to the second embodiment of the present invention has a semi-transmissive film pattern having a predetermined width in the center of the light-shielding film pattern, and the hole pattern in which the light-transmitting part is surrounded by the semi-transmissive film pattern. Has That is, in the area surrounded by the continuous light shielding part 31, it is the transmission auxiliary mask 4 (symbol 5 in the figure) which formed the semi-transmissive part 21 of constant width adjacent to the edge of the said light shielding part 31. FIG. The exposure light transmittance of the semi-transmissive portion 21 in Example 2 will be described later.

With the structure of each photomask of the comparative example 2, the reference example 2, and the Example 2 mentioned above, three types of samples which prepared the dimension of the hole H in the square of 4.0 micrometer, 2.5 micrometers, 2.0 micrometers of one side are prepared. It was. In addition, in Example 2 of this invention, all the width | varieties of the semi-transmissive part 21 of three types of samples were 0.5 micrometer.

In addition, in Example 2, about the sample of the dimension of the hole H of 4.0 micrometers and 2.5 micrometers of one side, the exposure light transmittance | permeability with respect to the representative wavelength i line of the semi-transmissive film used for the semi-transmissive part 21 is 30%. About the sample of the dimension of the hole H of 2.0 micrometers of one side, the exposure light transmittance with respect to the representative wavelength i line of the semi-transmissive film was 35%. Under this condition, as shown in FIG. 12 to be described later, the irradiation light amounts Eop of Reference Example 2 and Example 2 almost coincide.

In addition, the phase shift amount of the semi-transmissive film used in Reference Example 2 and Example 2 is 45 degrees with respect to the representative wavelength i line.

In addition, in the graph of FIG. 12 showing the results of the optical simulation, three plots are shown in each evaluation of Comparative Example 2, Reference Example 2, and Example 2, but these three plots are applied to the three types of samples. Each correspondence.

<Simulation condition, evaluation item>

Optical simulations when the photomasks having the hole patterns of Comparative Example 2, Reference Example 2, and Example 2 were respectively exposed by the exposure apparatus were performed. In optical simulation conditions, the numerical aperture NA of the exposure apparatus is 0.085 and the coherence factor σ is 0.9, and the intensity of the irradiation light source is broad light including i-line, h-line, and g-line, and the intensity ratio is g-line. : line h: i line = 1: 1: 1. In this optical simulation, evaluation items A to C shown in FIG. 11D were evaluated. Hereinafter, evaluation items A to C will be described.

<< A: amount of irradiation light [DOSE amount (Eop)] >>

Explanatory drawing of FIG.11 (d) shows the cross-sectional shape of the resist pattern formed with the photomask which has a hole pattern. The black part in the figure is a resist pattern which becomes an etching mask, and the white part therebetween is a removal pattern on the resist pattern corresponding to the hole H. As shown in FIG.

In addition, the irradiation light amount [DOSE amount Eop] here is the width | variety of the light emission part width CD of the hole H of a photo mask, and the width | variety of the removal pattern on the resist pattern formed by exposure light which permeate | transmitted the hole H. It evaluated as the amount of irradiation light required in order to become equal.

The smaller the value of the irradiation light amount Eop, the higher the production efficiency or the more energy saving.

<< B: resist inclination angle >>

The resist inclination angle in this optical simulation is the inclination angle of the boundary portion with the hole portion (removal pattern) of the black resist pattern shown in the explanatory diagram of FIG. This resist inclination angle expresses the inclination angle (90 degrees) in the case of perpendicular | vertical with respect to the surface of a to-be-transferred body when the transfer body is mounted horizontally as the maximum. The larger the resist inclination angle is, the better. The larger the resist inclination angle, the smaller the variation in the diameter and the width when the resist pattern is used as an etching mask.

<< C: resist film reduction >>

The film reduction amount with respect to the initial film thickness (1.5 micrometer) of a resist film is shown. The smaller the resist film reduction of the black resist pattern shown in the explanatory drawing of Fig. 11D, the more preferable. Resist film reduction can be severe, especially in dry etching.

<Simulation Result>

The simulation results of the evaluation items A to C are shown in FIG. 12 for each photo mask of Comparative Example 2, Reference Example 2, and Example 2. FIG. FIG. 12A shows the irradiation light amount, FIG. 12B shows the resist inclination angle, and FIG. 12C shows the resist film decrease.

As shown to Fig.12 (a), the irradiation light quantity has the largest comparative example 2, and reference example 2 and Example 2 are the same level. Similarly to the simulation results of Example 1 described above, even when the form of the hole pattern is adopted in the photomask of the present invention, the effect of reducing the amount of irradiation light is remarkably recognized as compared with the binary mask of Comparative Example 2.

As shown in FIG. 12B, the resist inclination angle has the largest binary mask of Comparative Example 2, but the resist inclination angle of Example 2 is hardly deteriorated as compared with this binary mask.

As shown in Fig. 12C, in Example 2, as in the binary mask of Comparative Example 2, almost no resist film reduction occurs (the value of Example 2 and the value of Comparative Example 2 overlap and are plotted. have).

As a comprehensive evaluation of the above evaluation items A to C, the photomask of the present invention can reduce the amount of irradiation light required for exposure, and can form a resist pattern having an excellent shape as an etching mask. This is for the semi-transmissive part formed adjacent to the edge of a light shielding part to exhibit the function which assists the transmitted light quantity of a light transmitting part, and to exhibit the effect of reducing the amount of irradiation light of an exposure apparatus. The significance of enabling such a resist pattern to be realized in a fine pattern which has conventionally been difficult to pattern is large.

In addition, in a photo mask having a hole pattern for forming a contact hole, there is a demand for not only to form a fine hole but also to control the inclination angle of the hole cross section to a desired value. For example, when a wiring-shaped groove is formed in the interlayer insulating film and a metal is buried, in consideration of the ease of embedding, a predetermined inclination angle (for example, 20 ° to 60 °) is formed in the groove with high precision. If it is intended to be considered. In such a case, in the photomask of Example 2 of the present invention, it is useful to control the inclination angle of the resist pattern serving as the etching mask by selecting the dimensions and the transmittance of the semi-transmissive portion, and the resist formed in a predetermined shape. It is also possible to make the pattern as part of the final product.

As mentioned above, although this invention was demonstrated with reference to some embodiment and Example, this invention is not limited to the said embodiment and Example. Various changes and modifications can be made by those skilled in the art within the spirit and scope of the invention as set forth in the claims.

Claims (7)

A photomask having a transmissive pattern on a transparent substrate, the translucent portion having a translucent film for transmitting a part of the exposure light, and a light shielding portion having a light shielding film formed thereon,
The semi-transmissive film has a transmittance of 2 to 60% and a phase shift of 90 ° or less with respect to a representative wavelength of exposure light used for the transfer of the transfer pattern.
And the transflective portion is formed adjacent to the edge of the light shielding portion and has a width not resolved by an exposure apparatus. The method of claim 1,
The semi-transmissive portion has a first semi-transmissive portion and a second semi-transmissive portion formed adjacent to edges facing the light-shielding portion, respectively, and the widths of the first and second semi-transmissive portions are not resolved by the exposure apparatus, respectively. A photo mask, characterized in that the width is equal to each other. The method of claim 1,
The transfer pattern is a line-and-space pattern, and a line-and-space having a line width or a space width of less than 3 µm is formed on the transfer object. The method of claim 1,
And the semi-transmissive portion is formed in a region surrounded by the successive light shielding portion, adjacent to the edge of the light shielding portion, at a predetermined width not resolved by an exposure apparatus. The method of claim 1,
The transfer pattern is a hole pattern, and forms a hole having a diameter of less than 3㎛ on the transfer object. As a pattern transfer method,
The pattern transfer method which uses the photomask in any one of Claims 1-5, and transfers the said transfer pattern on a to-be-transferred body using an exposure apparatus. A method of manufacturing a flat panel display,
The pattern transfer method of Claim 6 is used, The manufacturing method of the flat panel display characterized by the above-mentioned.

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