JPH1083062A - Half-tone type phase shift mask and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to suppress unnecessary light intensity attributable to four corner parts, by providing a light shielding layer at the four corner parts in a half-light transmission part formed into a rim shape in the periphery of the light-transmission part. SOLUTION: Regions not contributing to the phase shift effect in a half-tone type phase shift mask are analyzed in detail and these regions are provided with the light shielding layer. Namely, the light shielding layer 4 is provided at the four corner areas in the half-light transmission part 3 formed to the rim shape at the periphery of the light-transmission part 2. Consequently, the unnecessary light intensity is suppressed compared with the case where the light shielding layer 4 is not provided at the four corner parts in the half-light transmission part 3. Further, it is preferable to keep the width of the half- transmission part 3 to be 0.3 to 0.8×(λ/NA) form the standpoint of maintaining the light intensity characteristic of a principal pattern and suppressing a side peak. At this point, λ and Na indicate the wavelength of exposed light and numerical aperture of a stepper, respectively. Thus, the unnecessary light intensity attributable to the four corner parts is suppressed and leakage light from the half-light transmission part 3 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask capable of improving the resolution of a transfer pattern by giving a phase difference between exposure lights transmitted through a mask, and a method of manufacturing the same, and more particularly to a halftone type mask. And a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, two important characteristics required for photolithography, high resolution and securing a depth of focus, are in conflicting relations.
It has been clarified that the practical resolution cannot be improved only by shortening the wavelength (Semiconductor World 1990.12, Monthly Applied Physics, Vol. 60, November, 1991).

Under such circumstances, phase shift lithography has attracted attention as a next-generation photolithography technology. Phase shift lithography is a method of improving the resolution of optical lithography by changing only the mask without changing the optical system, and by providing a phase difference between the exposure light transmitted through the photomask, interference between transmitted light The resolution can be dramatically improved by utilizing the above.

A phase shift mask is a mask having both light intensity information and phase information.
Various types such as a die, an auxiliary pattern type, and a self-alignment type are known. These phase shift masks have a complicated structure and require a high level of technology for manufacturing as compared with a conventional photomask having only light intensity information.

As one of the phase shift masks, a phase shift mask called a so-called halftone type phase shift mask has recently been developed.

In this halftone type phase shift mask, a semi-transmissive portion (halftone film pattern) has a light blocking function of substantially blocking exposure light and a phase shift function of shifting (normally inverting) the phase of light. Since it has both functions, it is not necessary to separately form the light-shielding film pattern and the phase shift film pattern, and the feature is that the structure is simple and the manufacturing is easy.

Halftone type phase shift mask 10
As shown in FIG. 12, a mask pattern formed on a transparent substrate 1 is formed by a light-transmitting portion (transparent substrate exposed portion) 2 which transmits light having an intensity substantially contributing to exposure, and a mask pattern substantially exposed to light. A semi-transmissive portion (light-shielding portion and phase shifter portion) 3 that transmits light of an intensity that does not contribute (FIG. 3A), and the phase of light transmitted through this semi-transparent portion is shifted. By making the phase of the light transmitted through the semi-transmissive portion substantially inverted relative to the phase of the light transmitted through the translucent portion, the boundary between the semi-transmissive portion and the translucent portion Light passing through the vicinity and sneaking into each other's area due to the diffraction phenomenon is made to cancel each other, and the light intensity at the boundary is made almost zero, thereby improving the contrast, that is, the resolution of the boundary (FIG. 2B). ~ (D)).

[0008] As described above, the halftone type phase shift mask has a semitransparent portion having both a phase shift function and a light shielding function. That is, the semi-transparent portion functions as a phase shift layer at the boundary of the pattern, and functions as a light-shielding layer at other portions. Therefore, a small amount of leaked light reaches a portion where it is ideal to completely block the exposure light.
Normally, the overall exposure is adjusted so that even if the leakage light does not result in substantial exposure.

However, for example, as in the case where the thickness of the resist to be exposed formed on the object to be transferred varies greatly depending on the location, the required exposure amount varies greatly depending on the location of the object to be transferred. In such a case, the entire exposure must be set to a value that can cover the maximum exposure among the exposures required at each location of the transfer object. Otherwise, the entire exposure cannot be performed.

However, in such a case, for example, in a thick part where a large exposure amount is required, the influence of the light leaked from the semi-transmissive part is small, but in a thin part, the development by the exposure with the leak light is performed. It has been found that the subsequent reduction in the thickness of the resist may exceed an allowable range. FIG.
3 to 15 are explanatory diagrams of this situation.

FIG. 13 is a view showing an example of an object to be transferred in which the thickness of a resist to be exposed varies depending on the location, and FIG.
FIG. 15 is a view showing a state in which exposure is performed on an object to be transferred of FIG.
FIG. 5 is a view showing a transferred body after exposure and development shown in FIG.

The transfer object shown in FIG.
A conductive film 101 having a step of about 0.5 μm is provided thereon, and a positive resist film 102 for forming a pattern is formed thereon by spin coating. The transfer target is formed by pattern-exposing the resist 102 and developing the resist, forming a resist pattern, and then performing etching using the resist pattern as a mask to form a wiring pattern on the conductive film 101.

As shown in FIG. 14, the exposure of the resist film 102 is performed by a halftone type phase shift mask 10.
Let's consider the case. In this case, the thickness of the resist 102 in the region B where the conductive film 101 is thinner is larger than the two thicknesses of the resist 10 in the region A where the conductive film 101 is thick. For this reason, the value of the exposure amount is set to a large value capable of exposing the area B.

Then, as shown in FIG. 15, when the resist 101 is developed, the resist pattern 102a is reduced in film thickness in accordance with the light leaking from the semi-transparent portion 3. This amount of film reduction is not an amount that causes a problem during etching in a region B where the thickness of the resist film 102 is originally sufficiently large. However, in a region A where the resist film 102 is originally thin, the film thickness may be further reduced, and the function as a mask may not be sufficiently performed at the time of etching. For this reason, it is difficult to set the exposure amount, and in some cases, an optimum exposure amount may not be obtained. This situation is particularly serious when the transmittance of the semi-light-transmitting portion is high (for example, 10 to 15%) because the amount of exposure light energy leakage increases.

The halftone type phase shift mask is usually used as a mask (reticle) of a reduction projection exposure apparatus (stepper) which is an exposure apparatus used for semiconductor manufacturing. The stepper reduces a projection image obtained by projecting a reticle with exposure light using a projection lens, forms an image on a semiconductor wafer as a transfer target, and performs reduced projection exposure. In the reduced projection exposure, usually, the same pattern is repeatedly transferred and exposed to different positions on one semiconductor wafer to obtain a large number of semiconductor chips from one wafer. For this reason, when performing pattern transfer using this stepper, as shown in FIG.
Covering member (aperture) 20 provided on stepper
Exposure is performed by covering the peripheral region so that only the transfer region I of the phase shift mask 10 (reticle) is exposed with 0.

However, this aperture 200
However, it is difficult to install the transfer region with high accuracy (for example, an accuracy of 1 μm or less) in terms of mechanical accuracy. In many cases, the exposed portion protrudes into the transfer region around the outer periphery of the transfer region. Further, even if the aperture has a high precision and no protruding portion, the exposure light is diffracted and reaches the transfer target area because of the distance between the aperture and the transfer target.

As described above, when the aperture 200 allows the exposure light to pass through a wider area than the original transfer area, the following problem is found. That is, in the halftone type phase shift mask 10, the semitranslucent film 3 that normally transmits light having an intensity that does not substantially contribute to exposure is formed in the area to be transferred. Therefore, as described above, when the aperture 200 allows the exposure light to pass through a wider range than the original transfer area, the exposed portion is exposed to light having an intensity that does not substantially contribute to exposure. Of course, no problem arises with one exposure even if there is such a protruding portion. However, there are cases where the protruding and exposed portions (protruding exposed portions) overlap with the transfer area or overlap with the protruding and exposed portions in the next exposure in the same manner. In the exposure, even if the exposure amounts do not substantially contribute to the exposure, they may be added to reach an amount that contributes to the exposure. Therefore,
As a result, the same effect occurs as in the case where exposure is performed on a region that should not be exposed, and a defect occurs. Hereinafter, this point will be specifically described.

FIG. 17 is an explanatory view showing a phenomenon in which the exposed portions overlap. FIG. 17 is for the sake of simplicity. It is assumed that four transfers are performed adjacently on a wafer to which a resist to be exposed is applied, and regions E1, E2, E3, E4 is the transfer region, and the portions surrounded by the dotted lines outside the respective transfer regions are the protruding portions ΔE1, ΔE2, ΔE3, and ΔE4. The dimension (length and width) of each transfer area is I, the dimension (length and width) of the light passing hole of the actual aperture is I ′, and the dimension (width) of the protruding portion.
Is ΔI. The relative positions of the transfer areas E1, E2, E3, and E4 are set so as to be accurately adjacent to each other by an XY stage of a stepper or the like. Also, in FIG. 17, in order to make the description easy to understand, the protruding portion ΔE
1, ΔE2, ΔE3, and ΔE4 are shown in an enlarged manner.

As apparent from FIG. 17, the protruding portion Δ
As for E1, ΔE2, ΔE3, and ΔE4, overlapping portions occur between adjacent ones. These overlapping portions are represented by δE12, δE24, δE34, δE13, δE234, δE134,
Assuming that δE123 and δE124, the overlapping portions δE12 and δE2
4, the overlap number of δE34 and δE13 is 2 times,
In the overlapping portions δE234, δE134, δE123, δE124, 3
And at point O there is substantially four overlaps. Now, assuming that the light transmittance of the semi-transmissive film 3 is 15%, the same amount of exposure as in the case of passing through a film with a light transmittance of 30% is applied to the twice overlapping portion, and the light transmittance is applied to the three overlapping portions. 4
Exposure of the same amount as when passing through a film of 5% is performed, and exposure of the same amount as in the case of passing through a film with a light transmittance of 60% is performed on the overlapping portion four times. For this reason, in these overlapping portions, there is a case where exposure is performed to reach an intensity substantially contributing to exposure. As a result, after this exposure, the resist is developed, and a predetermined etching is performed on the wafer to form a pattern, so that an unnecessary pattern is formed in a portion that should not be formed, and a pattern defect is formed. Will occur.

In order to solve the above-mentioned problem of the light leakage of the semi-transmissive portion, the applicant of the present application has proposed a method of canceling light near the boundary between the transmissive portion and the semi-transmissive portion in the halftone type phase shift mask. By providing a light-shielding layer on the upper surface or the lower surface portion of the semi-transmissive portion except for a portion that substantially contributes, leakage of exposure light in the semi-translucent portion is prevented, and reduction in the film thickness of the resist after development due to exposure by the leak light. We are developing technology to solve the problem and applying for it. In addition, in order to solve the problem of overexposure, a light-shielding layer is provided in a non-transfer area other than the transfer area in the halftone phase shift mask, so that the gap between the light passing area of the aperture and the transfer area of the mask is reduced. We have developed a technology to solve the problem of overexposure due to a certain problem and filed an application at the same time (Japanese Patent Laid-Open No.
-128840).

[0021]

However, the above-mentioned conventional halftone phase shift mask has room for improvement as described below.

That is, in the semi-light-transmitting portion formed in a rim shape at the periphery of the light-transmitting portion, there is a problem that unnecessary light intensity appears at the four corners and the resist film is reduced.

Further, when the light-transmitting portion patterns are close to each other, there is a problem that unnecessary light intensity due to the proximity of the patterns appears.

Further, reticle alignment in a stepper is mainly performed by transmitted light. However, in the case of a halftone type phase shift mask, there is a problem that the S / N ratio is lower than that of a normal mask.

In addition, in the vicinity of a large pattern such as a monitor pattern for checking the overlay accuracy in wafer exposure, there is a problem that the resist film may be reduced even if there is no problem in this pattern portion.

The present invention has been made in view of the above-mentioned problems, and a phase shift mask which has solved the above-mentioned problems by using only a halftone region (semi-transmissive portion) for a portion requiring a phase shift effect. The purpose is to provide.

[0027]

In order to achieve the above object, a halftone type phase shift mask of the present invention is a mask for transferring a fine pattern, wherein a mask pattern formed on a transparent substrate is substantially formed. A light-transmitting portion that transmits light having an intensity that contributes to exposure, and a semi-light-transmitting portion that transmits light having an intensity that does not substantially contribute to exposure, and a phase of light transmitted through the semi-light-transmitting portion. To make the phase of the light transmitted through the semi-transmissive portion different from the phase of the light transmitted through the translucent portion, thereby passing near the boundary between the semi-transparent portion and the translucent portion. A halftone phase shift mask that improves the contrast at the boundary portion by utilizing the light canceling action of the light, and substantially contributes to the light canceling action near the boundary between the light transmitting portion and the semi-light transmitting portion. Light-shielding layer above or below the semi-transparent part except for parts In halftone phase shift mask provided, the four corners parts of the semi-light-transmitting portion formed on the rim in the periphery of the transparent portion, there a structure in which a light-shielding layer.

The halftone phase shift mask of the present invention is the same as the phase shift mask of the present invention, except that
Is the exposure wavelength and NA is the numerical aperture of the stepper,
The width of the semi-light-transmitting portion is 0.3 to 0.8 × (λ / NA).

Further, the halftone type phase shift mask of the present invention is a mask for transferring a fine pattern, and a mask pattern formed on a transparent substrate is made transparent by transmitting light having an intensity substantially contributing to exposure. A light part and a semi-light-transmitting part that transmits light having an intensity that does not substantially contribute to exposure, and shifts the phase of light transmitted through the semi-light-transmitting part to form the semi-light-transmitting part. By making the phase of the transmitted light different from the phase of the light transmitted through the light-transmitting portion, the boundary portion utilizing the canceling action of the light passing near the boundary portion between the semi-light-transmitting portion and the light-transmitting portion is used. A halftone phase shift mask for improving contrast of light, wherein light is shielded on a semi-transmissive portion except for a portion substantially contributing to a light canceling action near a boundary between the translucent portion and the semi-transmissive portion. Half-tone type phase shift mask with layer Oite, wherein when the transparent portion pattern are close, depending on the distance and placement between the light transmitting portion, it is a structure in which a light-shielding zone for removing unnecessary light intensity.

Further, the halftone type phase shift mask of the present invention is a mask for transferring a fine pattern, and a mask pattern formed on a transparent substrate is made transparent by transmitting light having an intensity substantially contributing to exposure. A light portion and a semi-light-transmitting portion that transmits light having an intensity that does not substantially contribute to exposure,
Further, by shifting the phase of the light transmitted through the semi-transmissive portion to make the phase of the light transmitted through the semi-transmissive portion different from the phase of the light transmitted through the translucent portion, the semi-transparent portion is shifted. A halftone type phase shift mask that improves the contrast at the boundary by utilizing the canceling action of light passing near the boundary between the light part and the translucent part, and a light shielding film is formed in a region that does not contribute to the phase shift effect. In the provided halftone phase shift mask, a light shielding layer is provided at least in a region around the alignment mark in consideration of the S / N ratio.

Further, the halftone type phase shift mask of the present invention is a mask for transferring a fine pattern, and a mask pattern formed on a transparent substrate is made transparent by transmitting light having an intensity substantially contributing to exposure. A light part and a semi-light-transmitting part that transmits light having an intensity that does not substantially contribute to exposure, and shifts the phase of light transmitted through the semi-light-transmitting part to form the semi-light-transmitting part. By making the phase of the transmitted light different from the phase of the light transmitted through the light-transmitting portion, the boundary portion utilizing the canceling action of the light passing near the boundary portion between the semi-light-transmitting portion and the light-transmitting portion is used. A halftone phase shift mask that improves the contrast of a halftone phase shift mask provided with a light-shielding film in a region that does not contribute to the phase shift effect. The area around the use monitor pattern is a structure in which a light-shielding layer.

Further, the halftone phase shift mask of the present invention has a configuration in which a light shielding layer is provided on a part or all of the non-transfer region in the above halftone phase shift mask of the present invention.

Further, the halftone phase shift mask of the present invention is the halftone phase shift mask of the present invention, wherein the halftone mask size is Sh, the dimension on the wafer is Sw, and Sh-Sw is the mask bias amount. M
When b, -0.1 μm <Mb <0.05 μm.

Further, in the method of manufacturing a halftone type phase shift mask of the present invention, a semi-transmissive film constituting a semi-transmissive portion is formed on a transparent substrate, and a light-shielding layer is formed on the semi-transmissive film. A halftone type phase shift mask blank having a light shielding film is used, and the light shielding film is patterned so that the light shielding film remains in a region where the phase shift effect is not required.

Further, in the method for manufacturing a halftone phase shift mask of the present invention, the method for manufacturing a halftone phase shift mask according to the present invention includes the step of:
When the semi-translucent film and the light-shielding film are laminated, the OD at the exposure wavelength
Is set to be 2 or more.

[0036]

According to the phase shift mask of the present invention, unnecessary light intensity caused by the four corners is shielded by shielding the corners at the four corners of the semi-light-transmitting portion formed in a rim shape on the periphery of the light-transmitting portion. Can be suppressed.

Further, when the light-transmitting portion patterns are close to each other, an unnecessary light intensity due to the proximity of the pattern is provided by providing a light-shielding band according to the degree of overlap of the rim-shaped halftone region (semi-light-transmitting portion). Can be suppressed.

Further, around the alignment mark,
Since the halftone region is not exposed, the S / N ratio at the time of reticle alignment in the stepper can be improved.

Similarly, halftone areas are not exposed around a large pattern such as a monitor pattern for checking the accuracy of wafer implantation during wafer exposure, so that the resist film does not decrease in these areas.

Hereinafter, the present invention will be described in detail.

The first invention analyzes in detail the areas which do not contribute to the phase shift effect (the effect of improving the contrast at the boundary portion by using the light canceling action) in the halftone type phase shift mask, and analyzes these areas. A light-shielding film is provided.

More specifically, for example, as shown in FIG. 1A, a semi-light-transmitting portion 3 formed in a rim shape around the light-transmitting portion 2
Are provided with light-shielding layers 4 at the four corners.

As a result, unnecessary light intensity can be suppressed as compared with the case where no light-shielding layer is provided at the four corners of the semi-transparent portion 3 as shown in FIG. This is illustrated in FIG.
It is clear from the comparison of the light intensity distribution diagrams corresponding to (a) and (b), respectively (FIGS. 2 (a) and (b)).

The conditions at this time are as follows: the size of the light transmitting portion 2: 0.4 μm × 0.4 μm;
0.2 μm × 0.2 μm, width of the semi-transparent portion 3: 0.65 ×
(Λ / NA) (the above sizes are values on the wafer), and the exposure conditions were an i-line stepper with NA: 0.57 and σ: 0.3.

In the present invention, from the viewpoint of maintaining the light intensity characteristics of the main pattern and suppressing side peaks, it is preferable that the width of the semi-transparent portion is 0.3 to 0.8 × (λ / NA). , 0.5 to 0.75 × (λ / NA). Here, λ is the exposure wavelength, and NA is the numerical aperture of the stepper.

Also, the width of the semi-light-transmitting portion is required to be strictly the same in the upper, lower, left and right directions to obtain characteristics, and the difference in width of the semi-light-transmitting portion is about 0.1 × (λ / NA). If so, there is no problem in the optical characteristics, which is within an acceptable range. Therefore, the exposure performed to expose the semi-transmissive portion requires less precision than the exposure performed when patterning the light-shielding film and the semi-transmissive film, so that a grid larger than the latter drawing grid can be selected. No big problem.

As shown in FIG. 3, it is natural that the effect can be further improved by providing the light shielding layer in a multi-stage at the four corners.

The first invention includes a mode in which a light shielding layer is provided at least in a region around the alignment mark. For example, as shown in FIG. 4, a light-shielding layer is provided in a region 12 around the alignment mark 11 in consideration of the S / N ratio. Thereby, the S / N ratio at the time of reticle alignment can be improved.

The first aspect of the present invention includes a mode in which a light-shielding layer is provided at least in a region around a monitor pattern for checking the accuracy of wafer implantation during wafer exposure (including alignment marks and / or numerals and character patterns for overlaying wafers). For example, as shown in FIG. 5, a light-shielding layer is provided in a region 14 around the monitor pattern 13 for checking the accuracy of wafer implantation during wafer exposure.

This is because these monitor patterns are several microns on the wafer, do not require a phase shift, and cannot be accurately monitored if the film thickness is reduced around the monitor patterns. A light-shielding layer is provided in a peripheral region.

According to a second aspect of the present invention, there is provided a halftone wherein a light shielding layer is provided above or below a semi-transparent portion except for a portion substantially contributing to a light canceling action near a boundary between the translucent portion and the semi-transmissive portion. In the pattern type phase shift mask, a light-shielding band for removing unnecessary light intensity is provided according to the distance and arrangement between the light-transmitting portions when the light-transmitting portion patterns are close to each other.

Here, the position where the light-shielding band is provided, the size and shape of the light-shielding band, and the like differ depending on the distance and arrangement between the adjacent light-transmitting portions, and unnecessary light intensity generated by the proximity of the light-transmitting portion pattern is eliminated. It is determined appropriately as needed.

In the simplest case, as shown in FIG. 6, in which the light-transmitting portion patterns 2 are adjacent to each other, the light-shielding band 20 can be inserted according to the following rule.

That is, assuming that the distance between the light transmitting portion patterns is d, 0.7 × (λ / NA) <d <1.6 × (λ / N
In the case of A), in the center portion between the patterns,
Unnecessary light intensity can be reduced by inserting a light-shielding band having a width of 0.05 × (λ / NA) to 0.6 × (λ / NA).

FIG. 7 shows a conventional example having no light-shielding band, and FIG. 9 shows a light intensity distribution thereof. FIG. 8 shows a light intensity distribution when a light-shielding band is provided. From FIGS. 8 and 9, it can be seen that the unnecessary light intensity is reduced when the light-shielding band is provided.

FIG. 10 is a graph in which the horizontal axis represents the distance d / (λ / NA) between the light transmitting portions and the vertical axis represents the light intensity between the patterns. The conditions at this time were as follows: light-transmitting part pattern size: 0.4 μm □, exposure condition: NA:
An i-line stepper of 0.57 and σ: 0.3 was used, the transmittance of the semi-transmissive portion was 9%, and the phase difference was 180 °.

FIG. 10 shows that the unnecessary light intensity is low in the region of 0.7 × (λ / NA) or less, and gradually increases from around 0.7 × (λ / NA). . Therefore, a light-shielding band is not required in a region of 0.7 × (λ / NA) or less, and the above-described case where a light-shielding band is required can be derived.

The present invention includes an embodiment in which a light-shielding layer is provided on a part or all of the non-transfer region in the halftone phase shift masks of the first and second inventions.

The above-described halftone type phase shift mask of the present invention has a semi-transmissive film constituting a semi-transmissive portion on a transparent substrate, and a light-shielding layer is formed above or below this semi-transmissive film. It can be manufactured by using a halftone type phase shift mask blank having a light shielding film and patterning the light shielding film so that the light shielding film remains in a region where the phase shift effect is not required.

In the present invention, the material constituting the semi-transmissive portion is not particularly limited, but oxidized molybdenum and silicon (abbreviated as MoSiO-based material), oxynitrided molybdenum and silicon (abbreviated as MoSiON-based material), Molybdenum and silicon nitrided (abbreviated as MoSiN-based material), silicon oxynitrided (abbreviated as SiON-based material), and the like are preferable. This is because the process for manufacturing the halftone phase shift mask of the present invention can be simplified and the accuracy can be improved.

The thickness of the light-shielding film is preferably set so that the OD at the exposure wavelength becomes 2 or more, preferably 3 or more when the semi-transparent film and the light-shielding film are laminated. This is because the purpose is to provide a sufficient light-shielding effect and to be able to treat a normal mask as well as patterning.

Since the halftone phase shift mask of the present invention having the above-described structure hardly produces a side peak, it can be exposed with an increased exposure amount like a normal mask. In general, the halftone mask size (pattern size) Sh and the dimension Sw on the wafer have the following relationship (1). Sh> Sw, Sh−Sw = approximately 0.05 μm (1) The exposure latitude is such that Sh is closer to Sw or Sh <Sw.
Is larger.

In the halftone type phase shift mask of the present invention, when Sh-Sw is used as the mask bias, the mask bias amount Mb can be set in the following range (2). −0.1 μm <Mb <0.05 μm (2)

For this reason, as shown in FIG. 18, a normal halftone mask can form a pattern with an exposure amount of X, but a side peak is resolved in a state of Y.
However, in the case of the halftone type phase shift mask of the present invention, a pattern can be formed even with the exposure amount of Y. Therefore, even with the same mask size, a pattern closer to or larger than the mask size can be formed on the wafer by increasing the exposure amount, so that a larger exposure latitude can be obtained.

[0065]

The present invention will be described below in more detail with reference to examples.

Embodiment 1 FIG. 11 is a view showing a process of manufacturing a halftone type phase shift mask according to one embodiment of the present invention.

In this embodiment, the semi-transparent layer has a thickness of 1
20 nm of nitrided molybdenum and silicon (MoS
iN-based material), and exposure light (wavelength 365 nm)
Is 9%, and the phase of the exposure light is 1%.
Shift by 80 °.

The light-shielding layer is made of Cr and has a thickness of 70 n.
m, which is formed in a region that does not contribute to the phase shift effect.

The halftone type phase shift mask having this configuration can be manufactured as follows.

Production of blank Using a mixed target of molybdenum (Mo) and silicon (Si: silicon) (Mo: Si = 20: 80 mol%), a mixed gas atmosphere of argon (Ar) and nitrogen (N ₂ ) ( Ar: 10%, N ₂ : 90%, pressure: 1.5 × 10
Molybdenum and silicon (MoS) nitrided on the transparent substrate 1 by reactive sputtering at ^-3 Torr).
A semi-transparent film 3 made of (iN-based material) was formed. Then
On the semi-translucent film 3, Cr is deposited to a thickness of 80 nm by sputtering to form a light-shielding film 4, and i-line (wavelength 36
5 nm) (FIG. 11).
(A)).

Next, a positive type electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is applied on the light shielding film 4 to a thickness of 50 nm.
0 nm and baking treatment to form an electron beam resist film 5, and an i-line with a resist (wavelength 365 n
m) was obtained (FIG. 11).
(A)).

[0072] Mask processing Next, a desired pattern to the electron beam resist film 5 (on description)
Then, the resist pattern 5a was formed by performing an electron beam exposure and developing and then performing a baking process (FIG. 11B).

Next, using the resist pattern 5a as a mask, the light-shielding film 4 was etched with a predetermined etching solution to form a light-shielding film pattern 4a (FIG. 11C). At that time, a proximity pattern was also formed partially (not shown).

Next, after etching the translucent film 3 (FIG. 11D), the resist pattern 5a was removed (FIG. 1).
1 (e)). In addition, the etching of the semi-transparent film 3 was performed under the following conditions using a parallel plate type dry etching apparatus of a reactive ion etching type.

Etching gas: mixed gas of CF ₄ and O ₂ Gas pressure: 0.2 Torr High frequency output: 100 W

Next, a positive electron beam resist (ZEP-810S: manufactured by Zeon Corporation) is coated on the entire surface of the substrate to a thickness of 500 n.
m and baking to form an electron beam resist film 6, and thereafter, the electron beam resist film 6 is subjected to electron beam exposure for forming a light-shielding pattern (FIG. 11).
(F)). At that time, the drawing was performed so that the light-shielding layer was formed even in the region of the detail not contributing to the phase shift effect, and a predetermined light-shielding band was formed between the adjacent patterns.

Next, the electron beam resist film 6 is developed to form a resist pattern 6a in a region which does not contribute to the phase shift effect.
Is formed (FIG. 11G).

Thereafter, using the resist pattern 6a as a mask, the exposed portion of the light-shielding film pattern is subjected to predetermined etching to expose a necessary halftone region (FIG. 11).
(H)).

Finally, the remaining resist pattern is removed to obtain a halftone type phase shift mask 10 (FIG. 11 (i)).

Evaluation In the above-described halftone phase shift mask, as in the prior art,
This solves the problem of light leakage from the semi-transparent portion and the problem of overexposure.

In this embodiment, furthermore, unnecessary light intensity due to the four corners is suppressed by shielding the four corners of the semi-light-transmitting portion formed in a rim shape on the periphery of the light-transmitting portion. This further reduces the light leakage of the semi-transparent portion.

The S / N around the alignment mark
By providing the light shielding layer in consideration of the ratio, the S / N ratio at the time of reticle alignment is improved.

Further, a light-shielding layer is provided around a large pattern such as a monitor pattern for checking overlay accuracy in wafer exposure, thereby preventing the resist from being reduced around the pattern.

Further, by providing a light-shielding band between the adjacent patterns, unnecessary light intensity due to the proximity of the pattern is suppressed.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not necessarily limited to the above embodiments.

For example, instead of forming the semi-transmissive portion as a single layer, a multi-layered structure including a low transmittance film and a high transmittance film may be used.

The light-shielding layer may be any film as long as it has etching selectivity with the halftone film (semi-transparent film). Depending on the material of the halftone film (semi-transparent film),
In addition to Cr, for example, chromium oxide, chromium nitride, chromium carbide, chromium containing silicon, molybdenum, tantalum or tungsten oxidation, nitride or carbide, molybdenum, tantalum or tungsten containing silicon, molybdenum, tantalum, Metals such as tungsten, titanium, and aluminum can also be used.

Further, it is also possible to manufacture using a back exposure process.

The light transmittance of the semi-transparent layer is usually 1 to
A range of 50% is sufficient, and practically a range of 3 to 15% is used.

[0090]

As described above, according to the halftone type phase shift mask of the present invention, the four corners of the semi-light-transmitting portion formed in a rim shape on the periphery of the light-transmitting portion are shielded from light. Unnecessary light intensity due to the four corners can be suppressed.

Further, when the light-transmitting portion patterns are close to each other, depending on how the rim-shaped halftone regions overlap,
By providing the light-shielding band, unnecessary light intensity due to the proximity of the pattern can be suppressed.

Further, around the alignment mark,
Since the halftone region is not exposed in consideration of the S / N ratio, the S / N ratio at the time of reticle alignment in the stepper can be improved.

Similarly, a halftone area is not exposed around a large pattern such as a monitor pattern for checking overlay accuracy in wafer exposure, so that the resist film does not decrease in these areas.

Further, according to the method of manufacturing a halftone phase shift mask of the present invention, the mask of the present invention can be manufactured easily and inexpensively with a high yield.

[Brief description of the drawings]

FIG. 1 is a plan view for explaining one embodiment of a halftone type phase shift mask of the present invention, wherein FIG.
(B) shows a conventional example.

2A and 2B are plan views showing light intensity distributions of the mask of FIG. 1, wherein FIG. 2A shows the present invention and FIG. 2B shows a conventional example.

FIG. 3 is a plan view showing a modification of the mask of FIG.

FIG. 4 is a plan view for explaining another embodiment of the halftone type phase shift mask of the present invention.

FIG. 5 is a plan view for explaining another embodiment of the halftone type phase shift mask of the present invention.

FIG. 6 is a plan view for explaining another embodiment of the halftone type phase shift mask of the present invention.

FIG. 7 is a plan view for explaining a conventional example.

8 is a plan view showing a light intensity distribution of the mask of FIG.

FIG. 9 is a plan view showing a light intensity distribution of the mask of FIG. 7;

FIG. 10 is a diagram showing the relationship between the distance between patterns and the light intensity.

FIG. 11 is a cross-sectional view for explaining an example of the manufacturing process of the halftone phase shift mask of the present invention.

FIG. 11 is a diagram for explaining the transfer principle of a halftone type phase shift mask.

FIG. 13 is a cross-sectional view for explaining the problem of light leakage.

FIG. 14 is a cross-sectional view for explaining a problem of light leakage.

FIG. 15 is a cross-sectional view for explaining the problem of light leakage.

FIG. 16 is a cross-sectional view for explaining the problem of overexposure.

FIG. 17 is a plan view for explaining the problem of overexposure.

FIG. 18 is a diagram for explaining a mask bias.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Translucent part 3 Semi-translucent part 3a Light semi-transmissive pattern 4 Light shielding part 4a Light shielding film pattern 5 Resist 5a Resist pattern 6 Resist 6a Resist pattern 10 Halftone type phase shift mask 11 Alignment mark 12 Peripheral area 13 Monitor pattern 14 Area around 20 Shading zone

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 5, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a plan view for explaining one embodiment of a halftone type phase shift mask of the present invention, wherein FIG.
(B) shows a conventional example.

2A and 2B are plan views showing light intensity distributions of the mask of FIG. 1, wherein FIG. 2A shows the present invention and FIG. 2B shows a conventional example.

FIG. 3 is a plan view showing a modification of the mask of FIG.

FIG. 4 is a plan view for explaining another embodiment of the halftone type phase shift mask of the present invention.

FIG. 5 is a plan view for explaining another embodiment of the halftone type phase shift mask of the present invention.

FIG. 6 is a plan view for explaining another embodiment of the halftone type phase shift mask of the present invention.

FIG. 7 is a plan view for explaining a conventional example.

8 is a plan view showing a light intensity distribution of the mask of FIG.

FIG. 9 is a plan view showing a light intensity distribution of the mask of FIG. 7;

FIG. 10 is a diagram showing the relationship between the distance between patterns and the light intensity.

FIG. 11 is a cross-sectional view for explaining an example of the manufacturing process of the halftone phase shift mask of the present invention.

FIG. 12 is a diagram for explaining a transfer principle of a halftone type phase shift mask.

FIG. 13 is a cross-sectional view for explaining the problem of light leakage.

FIG. 14 is a cross-sectional view for explaining a problem of light leakage.

FIG. 15 is a cross-sectional view for explaining the problem of light leakage.

FIG. 16 is a cross-sectional view for explaining the problem of overexposure.

FIG. 17 is a plan view for explaining the problem of overexposure.

FIG. 18 is a diagram for explaining a mask bias.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Translucent part 3 Semi-translucent part 3a Light semi-transmissive pattern 4 Light-shielding part 4a Light-shielding film pattern 5 Resist 5a Resist pattern 6 Resist 6a Resist pattern 10 Halftone phase shift mask 11 Alignment mark 12 surrounding area 13 monitor pattern 14 surrounding area 20 shading zone

Claims (9)

[Claims] 1. A mask for transferring a fine pattern, comprising:
The mask pattern formed on the transparent substrate, a light-transmitting portion that transmits light having an intensity substantially contributing to exposure, and a semi-transmissive portion that transmits light having an intensity that does not substantially contribute to exposure, Further, by shifting the phase of the light transmitted through the semi-transmissive portion to make the phase of the light transmitted through the semi-transmissive portion different from the phase of the light transmitted through the translucent portion, the semi-transparent portion is shifted. What is claimed is: 1. A halftone type phase shift mask for improving contrast at a boundary portion by utilizing a canceling action of light passing near a boundary portion between a light portion and a light transmitting portion, wherein In a halftone type phase shift mask provided with a light-shielding layer above or below a semi-transmissive portion except for a portion substantially contributing to the light canceling action near the boundary, a rim shape is formed on the periphery of the translucent portion Light shielding layers are provided at the four corners of the semi-transparent area. Halftone phase shift mask, characterized in that the. 2. When λ is the exposure wavelength and NA is the numerical aperture of the stepper, the width of the semi-transparent portion is 0.3 to 0.8 ×
2. The halftone phase shift mask according to claim 1, wherein (λ / NA). 3. A mask for transferring a fine pattern, comprising:
The mask pattern formed on the transparent substrate, a light-transmitting portion that transmits light having an intensity substantially contributing to exposure, and a semi-transmissive portion that transmits light having an intensity that does not substantially contribute to exposure, Further, by shifting the phase of the light transmitted through the semi-transmissive portion to make the phase of the light transmitted through the semi-transmissive portion different from the phase of the light transmitted through the translucent portion, the semi-transparent portion is shifted. What is claimed is: 1. A halftone type phase shift mask for improving contrast at a boundary portion by utilizing a canceling action of light passing near a boundary portion between a light portion and a light transmitting portion, wherein In a halftone type phase shift mask provided with a light-shielding layer above or below a semi-light-transmitting portion except for a portion substantially contributing to a light canceling action in the vicinity of a boundary, when the light-transmitting portion patterns are close to each other, Unnecessary light intensity depending on the distance and arrangement between the light parts Halftone phase shift mask, characterized in that a light-shielding zone for removing. 4. A mask for transferring a fine pattern, comprising:
The mask pattern formed on the transparent substrate, a light-transmitting portion that transmits light having an intensity substantially contributing to exposure, and a semi-transmissive portion that transmits light having an intensity that does not substantially contribute to exposure, Further, by shifting the phase of the light transmitted through the semi-transmissive portion to make the phase of the light transmitted through the semi-transmissive portion different from the phase of the light transmitted through the translucent portion, the semi-transparent portion is shifted. A halftone type phase shift mask that improves the contrast at the boundary by using the canceling action of light that has passed near the boundary between the light-transmitting part and the light-shielding film. A halftone type phase shift mask, wherein a light shielding layer is provided in at least a region around an alignment mark in consideration of an S / N ratio. 5. A mask for transferring a fine pattern, comprising:
The mask pattern formed on the transparent substrate, a light-transmitting portion that transmits light having an intensity substantially contributing to exposure, and a semi-transmissive portion that transmits light having an intensity that does not substantially contribute to exposure, Further, by shifting the phase of the light transmitted through the semi-transmissive portion to make the phase of the light transmitted through the semi-transmissive portion different from the phase of the light transmitted through the translucent portion, the semi-transparent portion is shifted. A halftone type phase shift mask that improves the contrast at the boundary by using the canceling action of light that has passed near the boundary between the light-transmitting part and the light-shielding film. A halftone type phase shift mask, wherein a light shielding layer is provided at least in a region around a monitor pattern for checking the accuracy of wafer implantation during wafer exposure. 6. A halftone type phase shift mask according to claim 1, wherein a light shielding layer is provided on a part or all of the non-transfer region in the halftone type phase shift mask according to claim 1. 7. The halftone phase shift mask according to claim 1, wherein a halftone mask size is Sh, a dimension on the wafer is Sw, and Sh-Sw is a mask bias amount Mb. 7. The halftone phase shift mask according to claim 1, wherein 1 .mu.m <Mb <0.05 .mu.m. 8. A halftone type phase shift mask having a semi-transmissive film constituting a semi-transmissive portion on a transparent substrate, and a light-shielding film constituting a light-shielding layer above or below the semi-transmissive film. A method of manufacturing a halftone type phase shift mask, characterized by using a blank and patterning a light shielding film so that the light shielding film remains in a region where a phase shift effect is not required. 9. The light-shielding layer according to claim 8, wherein the thickness of the light-shielding layer is set so that the OD at the exposure wavelength becomes 2 or more when the semi-transparent film and the light-shielding film are laminated. A method for manufacturing a halftone phase shift mask.