JP2002040625A - Mask for exposure, resist pattern forming method and method for producing substrate for the mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high precision mask for exposure which enables easy formation of a plurality of translucent films which do not course dust sticking or defects, and to simplify steps. SOLUTION: In the mask for exposure with a mask pattern formed on a light transmissive substrate, the mask pattern includes a translucent film pattern constructed, in such a way that the length of the light path of the pattern to light for exposure is made different from that of the transparent parts of the light transmissive substrate 10 by a prescribed amount, and the translucent film pattern is formed by stacking an Si layer 11 and an Si3N4 layer 12 containing the same element (Si) but having different composition in the optimum thickness each.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure mask used in photolithography, and more particularly to a translucent film pattern.
The present invention relates to an exposure mask having a phase shifter formed of a mask, an exposure mask substrate, and a method of manufacturing an exposure mask.

[0002]

2. Description of the Related Art In recent years, semiconductor integrated circuits have continued to be highly integrated and miniaturized. In manufacturing such semiconductor integrated circuits, lithography is particularly important as a key to processing.

In the current lithography technology, a method of projecting and exposing a mask pattern onto an LSI substrate via a reduction optical system is mainly used. If a high-pressure mercury lamp is used as a light source, the minimum line width is 0.5 μm. The degree is the limit. 0.5μ
For pattern dimensions of less than m, the development of direct drawing technology using a KrF excimer laser or electron beam, and X-ray equal-magnification exposure technology has been promoted, but due to reasons such as mass productivity and process versatility. Expectations for optical lithography have become very high.

In such a situation, for the light source, g
Various light sources such as X-rays, i-rays, excimer lasers, and X-rays are being studied. New resists are being developed for resists and new resist treatments such as REL are being studied. , CEL, image reverse method, etc. are also being studied.

On the other hand, recently, attempts have been made to miniaturize without changing the exposure light source. As one of the methods,
There is a phase shift method. The phase shift method is to improve the pattern accuracy by providing a phase inversion layer in a light transmitting portion to remove the influence of diffraction of light from an adjacent pattern.

Among the phase shift methods, there is a Levenson-type phase shift mask in which two adjacent light transmitting portions are alternately provided with a phase difference of 180 degrees. In this method, it is difficult to exhibit an effect when three or more patterns are adjacent. That is, the optical phase difference between the two patterns is 18
When the angle is set to 0 degrees, the other pattern has the same phase as one of the above two patterns. As a result, the phase difference 18
Patterns with 0 degrees are resolved but patterns with 0 degree phase difference are
There is a problem in that the resolution is not resolved between the cameras. In order to solve this problem, it is necessary to fundamentally review the device design, and there is considerable difficulty in putting it to practical use immediately.

Therefore, there is a halftone type phase shift mask as a technique that uses the phase shift method and does not require a change in device design. In order to maximize the effect of the phase shift method, it is important to optimize the phase difference between the light transmitted through the transparent portion and the light semi-transmissive film and the amplitude transmittance ratio between the two. The phase difference and the amplitude transmittance ratio are uniquely determined by the optical constants (complex refractive index n-ik, where i is a unit imaginary number) and the film thickness of these films. That is, in order to obtain a desired phase difference and an amplitude transmittance ratio, it is necessary to satisfy a certain relationship between the optical constant and the film thickness. However, since the optical constant is a value specific to a substance, it is difficult to satisfy a desired condition with a single-layer film.

FIG. 19 shows the structure of an ideal halftone phase shift film. The mask formed by this method includes a light transmitting portion 1a and a light translucent film 1 on a light transmitting substrate 1.
b, the light translucent film 1b is formed with an amplitude transmittance of 10 to 40% with respect to the light transmitting portion 1a, and the phase of light transmitted therethrough is changed by 180 degrees with respect to the light transmitting portion. is there. First layer 2 for satisfying these objects
The light semi-transmissive film 1b is configured by a two-layer structure of the first layer 2 and the second layer 3 that adjusts the phase difference generated by the first layer 2 to 180 degrees.

As described above, in the conventional halftone type phase shift mask, the halftone portion has a two-layer structure, the amplitude transmittance is adjusted by the first layer 2, and the halftone portion is generated by the first layer 2 by the second layer 3. The temperature is adjusted so as to be 180 ° C. together with the retardation. However, as a material used for these layers, conventionally, Cr, MoSi, or the like is used for the first layer, and SiO ₂ , M
gF ₂ , CaF ₂ , Al ₂ O ₃ or the like is used. Therefore, it is necessary to form a film in two different environments in order to form a halftone portion. For example, there is a method in which a Cr film is formed using a sputtering device for forming a first film, and a SiO ₂ film is formed using a CVD method for forming a _second film.

[0010] However, in this type of method, the film is formed by two times.
Since the cleaning is performed separately, there is a problem that dust adheres during transportation and the number of defects increases. Also, at the time of processing, since elements to be processed are different, a plurality of kinds of foreign gases (for example, when a translucent film is composed of a Cr / SiO ₂ film, Cr is a chlorine-based gas and SiO ₂ is a fluorine-based gas). Etching using a gas). Further, although a transparent film is used for the second layer, the transparent film has a small refractive index, so that the thickness of the phase shifter is large. For this reason, there is also a problem that processing accuracy is poor.

In the exposure step, a blind is provided in the projection exposure apparatus to prevent exposure light from leaking from an alignment or inspection mark existing outside the pattern area on the mask, and cuts light outside the pattern area. ing. In addition, since the image of the blind causes blurring of the image of about 100 μm on the wafer, it does not play a role of dividing the pattern area on the wafer. For this reason, conventionally, as shown in FIG. 20A, a light-shielding pattern 101 is formed so as to cover the periphery outside the pattern area on the mask. However, when the exposure mask is formed only of the translucent film, instead of the light-shielding pattern existing in the peripheral area outside the pattern area, which is conventionally intended to separate the pattern area, as shown in FIG. The pattern 201 will be used. At this time, the light that has passed through the translucent film existing on the boundary of the pattern region irradiates the adjacent pattern on the wafer by the amount of the transmittance of the translucent film × the exposure amount. For this reason, as shown in FIG. 21, in the irradiation area, the amount of exposure is substantially excessive, and the pattern area becomes thinner, and furthermore, the depth of focus becomes insufficient.

[0012]

As described above, in the conventional halftone type phase shift mask, there are problems that the number of steps is increased in forming a translucent film, and that dust adheres and defects occur. It was difficult to maximize the phase shift effect.

Further, when the exposure mask is formed only of the translucent film, the translucent pattern is used even in the peripheral area outside the pattern area, which has conventionally been intended to divide the pattern area, and therefore exists at the boundary of the pattern area. The light that has passed through the translucent film irradiates an adjacent pattern on the wafer by an amount equal to the transmittance of the translucent film × the amount of exposure. For this reason, in the irradiation area, there has been a problem that the exposure amount is substantially excessive and the pattern area is narrowed, and furthermore, the depth of focus is insufficient.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to enable a plurality of translucent films to be easily laminated without causing adhesion of dust and generation of defects. An object of the present invention is to provide an exposure mask and a method for manufacturing the same, which can simplify the steps and can maximize the phase shift effect.

Further, the present invention provides an exposure mask which does not cause problems such as a thinning of a pattern area and a lack of depth of focus even when an exposure mask is formed only of a translucent film. With the goal.

[0016]

According to the present invention, there is provided an exposure mask, wherein a phase difference between a transparent portion of the light transmitting substrate and a transparent portion of the light transmitting substrate is different within a range of 180 ± 10 degrees and an amplitude transmittance. 1
A translucent pattern composed of a single translucent layer or at least one translucent layer and a first translucent multilayer of transparent layers adjusted to be 0 to 40%; A light-shielding layer or a second translucent film having an amplitude transmittance of 10 to 40%, which is further laminated on the region of the portion and adjusted so that the amplitude transmittance of the region is 5% or less. I do.

Further, the exposure mask of the present invention is characterized in that the partial region includes at least a peripheral region outside a region that contributes as a semiconductor element when transferred onto a wafer.

Next, a method of forming a resist pattern according to the present invention is characterized in that a substrate coated with a resist is exposed to light through a mask for exposure according to claim 1 to form a resist pattern.

The method for manufacturing a mask substrate for exposure according to the present invention comprises:
A single-layer semi-transparent film layer on the light-transmitting substrate, the phase difference of which is different from the transparent part of the light-transmitting substrate in the range of 180 ± 10 degrees and the amplitude transmittance is adjusted to 10 to 40%. Or a step of forming a first translucent film comprising at least one translucent layer and a transparent layer, and further laminating the whole or part of the first translucent film, and the amplitude transmittance of the region is 5%
A method for manufacturing an exposure mask substrate, comprising: forming a light-shielding layer or a second translucent film having an amplitude transmittance of 10 to 40% adjusted to be as follows. Between the oxide film, the nitride film, the hydrogenated film, the carbonized film and the halogenated film in the processing of the light-shielding layer or the second translucent film having an amplitude transmittance of 10 to 40%. Forming a third film made of any one of the above.

Further, in the method of manufacturing an exposure mask according to the present invention, the phase difference between the transparent portion of the light transmitting substrate and the transparent portion of the light transmitting substrate may be different within a range of 180 ± 10 degrees and the amplitude transmittance may be one.
A first layer composed of a single translucent layer or at least one translucent layer and a transparent layer adjusted to be 0 to 40%.
A first translucent film forming step of forming a semi-transparent film, a third film forming step of forming a third film on the first semi-transparent film, and an amplitude transmission as a whole 5% rate
A second translucent film forming step of forming a light-shielding layer or a second translucent film having an amplitude transmittance of 10 to 40% adjusted as follows, and the second film using the third film as an etching stopper. And an etching step for selectively removing the translucent film.

[0021]

According to the present invention, a translucent film is formed of at least two layers, and some elements of each layer are made common, so that the translucent film can be formed by the same apparatus, and furthermore, its patterning is performed. At this time, etching can be performed with the same type of etchant. Therefore, it is possible to simplify the process for forming the translucent film. Further, even if the composition of a single layer that achieves the desired amplitude transmittance and phase difference as a translucent film is known, it may be difficult to realize a material having that composition. At this time, if the composition of the single layer is set to be equal to the overall composition of the plurality of layers partially different in composition, a layer equivalent to the single layer is formed by the stable plurality of easy-to-create layers. can do. That is,
By forming a translucent film with a plurality of layers containing the same element as in the present invention, the manufacturing process can be simplified and the phase shift effect can be maximized.

According to the third aspect of the present invention, since the exposure light is shielded at least in the area of the mask including the translucent pattern that reaches the wafer by the transfer outside the pattern area, the Thinning and lack of depth of focus can be prevented. For example, in the exposure result of a positive resist using an i-line translucent mask having an intensity transmittance of 2%, a pattern obtained by modifying a 0.55 μm line and space pattern to a desired size with an appropriate exposure amount is further exposed. X: Irradiation once with light corresponding to the intensity transmittance of the mask resulted in a pattern dimension of 0.49 μm, which is about 10% smaller than the desired value.
However, according to the above configuration, the exposure light can be shielded at least in a region outside the pattern region where the light reaches the wafer by transfer. Note that this translucent film for shielding light can be used inside the pattern region in addition to shielding the outside of the pattern region. In other words, when the resist pattern pattern on the wafer formed by the translucent mask pattern by the multiple exposures causes a significant film thickness phenomenon, the translucent film may be laminated in a region excluding the edge portion of the translucent pattern. It is possible to reduce the thickness of the resist pattern.

According to the fourth aspect of the present invention, an oxide film or a conductive film is interposed between the first translucent film and the second translucent film constituting the phase shift layer. Since the oxide film or the conductive film functions as an etching stopper, the phase shift layer can be selectively removed while maintaining the good condition, so that a good exposure mask without easily narrowing of the pattern and lack of depth of focus can be obtained. Can be formed.

When an oxide film is used, it is only necessary to oxidize the surface in the same chamber, and the formation is extremely easy.

Further, when a conductive film is used, charge-up can be prevented.

According to the sixth aspect of the present invention, the third film such as a hydroxide film, a nitride film, a carbonized film, a halogenated film, an oxide film, or a conductive film is formed.
Film acts as an etching stopper, so it can be selectively removed while maintaining the phase shift layer in good condition, making it possible to easily form a good exposure mask without narrowing of the pattern and lack of depth of focus Becomes

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing the embodiments, the basic principle of the present invention will be described.

When an attempt is made to use a translucent film as a single layer, it is necessary to control the phase of light transmitted through the translucent film at 180 degrees ± 10% with respect to the phase of light transmitted through the transparent portion.
In addition, it is necessary to set the transmittance of the translucent film to a desired value. The value of ± 10% shifts the phase difference from 180 degrees by simulation. In this case, the range in which the deterioration of the depth of focus falls within 10% is 180 degrees ± 10%.
It is determined from the degree.

In order to obtain the maximum resolution with a translucent film phase shift mask, the optical constant of the translucent film must satisfy the following conditions. Assuming that the complex electric field vector of the incident light is EO, the complex electric field vector of the light transmitted through the transparent region is E1, and the complex electric field vector of the light transmitted through the semi-transparent film region is E2, the relationship is as follows: E1 = t1 · E0 ... (1) E2 = t2 · E0 (2) Here, t1 and t2 are amplitude transmittances.

In order to obtain the maximum effect with the phase shift mask, the relationship between the amplitude transmittance ratio of transmitted light and the phase difference is expressed by the following equations (3) and (4). .1 ≦ | E1 | / | E2 | ≦ 0.4 (3) 170 degrees ≦ | δ1−δ2 | ≦ 190 degrees (4) Here, E1 = | E1 | exp (δ1) E2 = | E2 | exp (δ2) The amplitude transmittances t1 and t2 of the light in the translucent film region and the transmission region in the expressions (1) and (2) are the reflectance, the transmittance, and the film transmittance at the interface between the material constituting these regions and another medium. It can be easily obtained by considering multiple reflection at the film thickness T of the substance in consideration of the absorbance. The reflectance and transmittance of a substance can be obtained from the refractive index n and the extinction coefficient k. The absorbance of the film can be obtained from the extinction coefficient k.

Since the translucent film in question is a phase shifter layer, considering the phase difference of 180 degrees with respect to the aperture, the film thickness T is given by T = λ / 2 (n− 1)... (5) The transmittance t obtained as an actual measurement value from the above variables
Is obtained by t = F (n1, k1, n0, k0, T) (6). Here, n0 and k0 indicate the refractive index and extinction coefficient of the medium and are specific values.
The amplitude transmittance t can be uniquely obtained as the relationship between 1, k1.

Based on the above concept, for example, the wavelength 436
Assuming a g-line exposure of nm, the phase is set to 180 ± 10 °, the amplitude transmittance is set to 15 ± 5%, the refractive index n is changed, and the corresponding k is obtained. Car
Can draw. In FIG. 5, the vertical axis indicates the extinction coefficient k, the horizontal axis indicates the refractive index n, and the broken line (a) indicates a relationship between k and n when the amplitude transmittance is 10% and the phase is 170 degrees. ) Is a curve showing the relationship between k and n when the amplitude transmittance is 20% and the phase is 190 degrees.
It is a curve which shows k and n relation at the time of a degree. The region between the broken lines (a) and (b) is the allowable range at this time, and if the point determined by the refractive index n and the extinction coefficient k of a certain material is within the range between the broken lines, the material is simply The layer film has the function of a halftone type phase shift film.

In the case of g-line, a film satisfying this condition is used as shown in FIG.
2 includes amorphous Si indicated by points. However, when considering i-line exposure wavelength 365 nm, as shown in FIG. 13, amorphous Si _{(N 2} gas 0% point) takes a value outside the allowed range. Therefore, it is understood that it is impossible to form a single-layer halftone phase shift film using amorphous Si by i-line exposure.

By the way, Si ₃ N obtained by converting Si into N _2
4 (point of 80% of N ₂ gas) is also out of the allowable range when the same examination is performed. However, it can be seen that when the two points of amorphous Si and Si ₃ N ₄ are connected by an arbitrary curve, a region sandwiched between the broken lines is always obtained. That is, if there is a substance having an intermediate property between amorphous Si and Si ₃ N ₄ , the substance falls within the allowable range. For forming this film, reactive sputtering using Si and N ₂ is effective. At this time, a film having any physical properties can be obtained by changing the reaction ratio of N ₂ . The physical property values at this time are indicated by black circles. When a curve passing through a black circle is drawn, the curve passes through a region between dashed lines. The optimum conditions obtained here are as follows: n = 3.30, k = 1.19 when the flow rate of nitrogen gas during sputtering is 15%.
By setting the film thickness to S3.5 nm, the amplitude transmittance ratio becomes 0.142 and the phase difference becomes 180 degrees. By forming the Si ₃ N ₄ film with the changed reaction ratio in this manner, a desired single-layer halftone type phase shift film can be formed.

Further, KrF excimer laser with a wavelength of 248 nm - when considering the exposure by The, as in the case of i-line exposure, as shown in FIG. 14, amorphous Si and Si ₃
Physical properties of the N ₄ is an unacceptable, materials with these intermediate properties were found to fall within the allowable range.

The boundary condition can be set by fixing the phase to 180 degrees and giving a margin to the amplitude transmittance, or by setting the amplitude transmittance to have a margin to the phase. is there. Further, the allowable values may be changed from the values described in this description in consideration of the effects and effects on the resist process and the like.

As a result of our intensive studies as materials satisfying the above conditions, silicon, a mixture containing silicon,
A mixture of silicon, germanium, a compound containing germanium, a substance formed of any one or a mixture of two or more of mixtures containing germanium, or Cr,
Al, Ti, Sn, In, Co, or other metal elements, metal compounds, and oxides, nitrides, hydrides, carbides, and halides formed of any one or a mixture of two or more thereof Was found to satisfy the above two conditions. In particular, silicon can be said to be a very effective translucent film in the g-line region and SiN in the i-line and KrF regions. Table 1 shows the properties of these substances.

[0038] By implanting ions such as As, P, and B into the translucent film, it is possible to slightly adjust the quality of the formed film, for example, adjust the optical constant.

Further, by heating silicon to 500 ° C. or more, the amorphous state can be changed to polycrystal, or from polycrystal to single crystal, continuously or intermittently. Is obtained.

The basic concept for producing a single translucent film has been described so far. However, when a single translucent film is to be produced, the composition ratio of the compound may be difficult depending on the film. . For example, when an i-line single-layer semi-transparent film is formed by adjusting the composition ratio of silicon and nitrogen, the phase difference and transmittance satisfy the refractive index n and the extinction coefficient k at which silicon and nitrogen satisfy the optimum extinction coefficient k. The composition ratio is silicon: nitrogen = 1: 0.60.
Must be about. This is because the composition ratio of nitrogen is smaller than the composition ratio of the Si ₃ N ₄ film (silicon: nitrogen = 1: 1.33) usually obtained by nitrogenating silicon, and fine adjustment of the nitrogen flow rate is required.

When fine adjustment is required, two or more kinds of semi-transparent films having two different composition ratios, for example, Si (silicon: nitrogen = 1: 1) are formed, rather than forming a single-layer semi-transparent film.
0) and Si ₃ N ₄ (silicon: nitrogen = 1: 1.33). At this time, Si
When the sputter amount of Si ₃ N ₄ molecules with respect to the sputter amount 1 of molecules is obtained, 0.042 is obtained. If the sputter is performed twice under these conditions, a desired translucent phase shift film equivalent to that of a multilayer is obtained. Is obtained. When the KrF translucent film is separated from the Si ₃ N ₄ film in the same manner as the i-line, silicon:
It is necessary that nitrogen = 1: 0.9, and for that, S
By setting the sputtering amount of Si ₃ N ₄ molecules to 0.74 with respect to the sputtering amount of i molecules of 1, a desired translucent film phase shift can be obtained by two types of translucent films composed of Si and Si ₃ N ₄ films. be able to.

Note that these films are formed by considering Si as a common element. Silicon is used as a target, which is sputtered, and then sputtered with flowing nitrogen to obtain Si ₃ N _4. Deposit the film. In this sputtering process, the target is fixed to one type,
Since the same apparatus can be used and only the processing for the common element Si is required for the processing, the processing can be performed at once by reactive etching using a fluorine-based gas. C
Compared with a two-layer semi-transparent phase shift film made of different elements of r and SiO ₂ , the steps of film formation and processing can be omitted.

The material for forming the translucent film is S
The material is not limited to i and Si ₃ N ₄ , and various materials can be selected and used. 15 to 18 show the relationship between the refractive index and the extinction coefficient of various materials. 15 Cr-CrO _2, 16 _Al-Al 2 _{O 3,} 17 Ti-TiO, FIG. 18 is a GaAs-GaAsO.
In these figures, the upper figure shows the i-line (wavelength 365n).
m), the lower figure shows the case of KrF line (wavelength 248 nm). In these figures, each material composition may be determined so as to fall within a region (allowable range) between the upper broken line and the lower broken line. The composition obtained here can be applied not only to the case of the present invention but also to the case where a composition ratio is controlled according to reaction conditions to form a single-layer semi-transparent film.

Here, for example, Ti-T under KrF exposure conditions
As seen in the iO transition, if the value does not cross the allowable range, it may be considered that the halftone phase shift film according to the present invention cannot be formed. In addition, the Cr-
When the end-point substance exists at the boundary within the allowable range as seen in the CrO transition, the amplitude transmittance is 20% and the phase difference is 1 during exposure.
If 90 degrees can be regarded as an allowable range, the end point substance can be used as it is.

Embodiment 1 FIG. 1 is a sectional view showing a process for manufacturing an exposure mask according to a first embodiment of the present invention. This exposure mask was formed by sputtering as a translucent film pattern.
It is characterized by using a pattern consisting of a two-layer semi-transparent film of i and Si ₃ N ₄ and is used as a mask for i-line projection exposure.

First, as shown in FIG. 1A, a film having a thickness of 71 nm is formed on a silicon oxide substrate 10 by a sputtering method.
Is formed. Subsequently, a 19 nm thick Si ₃ N ₄ film 12 was formed while introducing nitrogen gas. At this time, the two-layer semi-transparent phase shift film has a phase difference of 180 degrees with respect to the silicon oxide substrate 10 and an amplitude transmittance of 22.4.
%Met.

Next, as shown in FIG. 1B, after a resist 13 for electron beam is deposited to a thickness of 0.5 μm, a conductive film 14 is further formed to a thickness of about 0.2 μm.

Next, as shown in FIG. 1C, a pattern is formed on the conductive film 14 with an electron beam at 3 μC / cm ² and further developed to form a pattern of the resist 13.
Here, the formation of the conductive film 14 is for preventing the charge-up of the electron beam when the resist 13 is insulative.

Next, as shown in FIG. 1D, the Si ₃ N ₄ film 12 exposed from the resist pattern is formed by reactive ion etching with a mixed gas of CF ₄ and O ₂ using the resist pattern as a mask. The silicon film 11 is sequentially removed. Then, by finally removing the resist pattern, a phase shifter including the Si ₃ N ₄ film 12 and the silicon film 11 can be obtained as shown in FIG.

In this example, a silicon film and Si ₃ N
_{Although the four} films were formed by sputtering, each film may be formed by a CVD method. Further, the processing of the silicon film and the Si ₃ N ₄ film may be performed by CDE (chemical dry etching) or wet etching.

Through the exposure mask thus formed, a substrate called PFR7750 (manufactured by Nippon Synthetic Rubber Co., Ltd.) coated with 1.54 μm of resist was exposed to a g-line at 1 g.
/ 5 reduction exposure (NA = 0.54, σ = 0.5) was performed to form a pattern. The exposure amount at this time is 300 mJ / c.
It was m ^2. What was conventionally resolved with a focus margin of 0 μm using a pattern of 0.45 μm can be resolved at 0.7 μm by using the mask of this embodiment.

Even with respect to the contact hole pattern, a 0.50 μm pattern which was not resolved by the conventional exposure was formed.
It was confirmed that the resolution was 1.5 μm.
Further, by processing the substrate using the resist pattern transferred and formed using this mask as a mask, a better processed shape can be obtained.

Embodiment 2 Next, a second embodiment will be described.

This exposure mask has a semi-transparent film pattern.
And Si formed by sputtering₃
N₄Kr is characterized by using a film pattern.
It is used as a mask for F. here,
74 nm thick silicon film 1 on silicon oxide substrate 10
Create 1. While continuously introducing nitrogen gas, ₃
N₄The film 12 was formed to a thickness of 70 nm. At this time from two layers
The semi-transparent phase shift film corresponds to the silicon oxide substrate 10.
The phase difference was 180 degrees and the amplitude transmittance was 21.5%.

After the electron beam resist 13 is deposited to a thickness of 1.5 μm in the same manner as in the first embodiment, a conductive film 14 is further formed to a thickness of about 0.2 μm. Drawing is performed on the conductive film with an electron beam at 6 μC / cm ² , and further developed to form a resist pattern.

Using this resist pattern as a mask, CF
_The Si ₃ N ₄ film 12 and the silicon film 11 exposed from the resist pattern are sequentially removed by reactive ion etching using a mixed gas of O ₄ and O ₂ . Finally, the resist pattern is removed to remove the Si ₃ N ₄ film 12 and the silicon film 1.
1 can be obtained.

A KrF resist, referred to as XP8843 (manufactured by Shipley Co., Ltd.), having a thickness of 1.0 μm, was applied through the exposure mask thus formed to KrF
1/5 reduction exposure using excimer laser (NA = 0.4, σ =
0.5) to form a pattern. The exposure amount at this time was 40 mJ / cm ² . What was conventionally resolved at a focus margin of 0 .mu.m with a 0.30 .mu.m pattern can be resolved at 0.7 .mu.m by using the mask of this embodiment. Regarding the contact hole pattern, it was confirmed that the 0.30 μm pattern which was not resolved by the conventional exposure was resolved by the focus margin of 1.2 μm.

In this example, the formation of the silicon nitride film as the phase shifter was performed by sputtering while controlling the amount of nitrogen gas using silicon, but a mosaic target of silicon and silicon nitride was used. A sputtering method or a CVD method in which the gas ratio is controlled may be used. Further, the film thickness may be set to an appropriate thickness without departing from the spirit of the present invention. Further, in order to finely adjust the refractive index and the amplitude transmittance, ion implantation or heat treatment may be performed to modify the surface.

Embodiment 3 Next, a third embodiment will be described.

This embodiment relates to an i-line exposure mask formed using Cr and CrO ₂ . When Cr is formed as a single-layer translucent film by reactive sputtering, a desired translucency can be obtained by adjusting the flow rate of oxygen gas so as to provide an environment in which the composition ratio of oxygen element to Cr element is about 1.8. It was confirmed that a phase shift film was obtained.

Next, considering that this condition is formed by a two-layer film of Cr and CrO ₂ , by setting the molecular composition ratio of each to Cr: CrO ₂ = 1: 0.567, the position relative to the silicon oxide substrate is improved. A phase difference of 180 degrees and an amplitude transmittance of 18% can be obtained.

First, as shown in FIG. 2A, a film having a thickness of 70 nm is formed on a silicon oxide substrate 10 by a sputtering method.
Is formed. Subsequently, a 42 nm thick CrO ₂ film 22 was formed while introducing oxygen gas.

Next, as in the first embodiment, an electron beam resist is formed to a thickness of 1.0 μm, and 6 μC
/ Cm ² , and further developed to obtain a resist pattern.

Using this resist pattern as a mask, Cl
₂And O₂For reactive ion etching with mixed gas
The Cr film 21 and C exposed from the resist pattern
rO ₂The film 22 is sequentially removed. And finally resist
By removing the pattern, as shown in FIG.
Cr film 21 and CrO₂Obtain phase shifter consisting of film 22
Can be

In this embodiment, the desired amplitude transmittance
Is about 26%, CrO ₂Use a single-layer film
If the film thickness is controlled to 130 nm, CrO₂Only from the membrane
Phase shifter can be obtained.

A substrate coated with an i-line resist (PFRIX500 (manufactured by Nippon Synthetic Rubber Co., Ltd.)) having a thickness of 1.3 μm was exposed to i-line of a mercury lamp through a projection exposure mask formed in this embodiment. / 5 reduction exposure (NA = 0.5, σ
= 0.6) to form a pattern. The exposure required at this time was 300 mJ / cm ² . For line & space patterns, 0.3 in conventional exposure
What was resolved at a focus margin of 0 μm with a pattern of 5 μm was changed to a focus margin by the mask of this embodiment.
It was possible to resolve with gin = 0.9 μm.

As for the contact hole pattern, it was confirmed that the 0.40 μm pattern, which was not resolved by the conventional exposure, was resolved by the focus margin of 1.5 μm. Further, by transferring the substrate using this mask and processing the substrate using the formed resist pattern as a mask, a better processed shape can be obtained.

[0068] In the present embodiment, it may be formed by CVD or the like to control the composition ratio of the atmosphere gas formation shifter film made of CrO _X. In this embodiment, Cr and CrO were used.
Using chemical etching the _second etching (CDE) or wet etching (using ceric ammonium nitrate solution) may be.

Embodiment 4 Next, a fourth embodiment will be described.

This embodiment relates to an i-line exposure mask formed using Al and Al ₂ O ₃ . When Al is formed as a single-layer translucent film by reactive sputtering, a desired translucency can be obtained by adjusting the flow rate of the oxygen gas so as to provide an environment in which the composition ratio of the oxygen element to the Al element is about 1.40. It was confirmed that a phase shift film was obtained.

Next, this condition was changed to ₂ for Al and Al ₂ O ₃ .
Considering the formation of a layer film, it is possible to obtain a phase difference of 180 degrees and an amplitude transmittance of 15% with respect to a silicon oxide substrate by setting each molecular composition ratio to Al: Al ₂ O ₃ = 1: 18.3. Can be.

First, as shown in FIG. 3A, a film having a thickness of 23 nm is formed on a silicon oxide substrate 10 by a sputtering method.
Is formed. Subsequently, an Al ₂ O ₃ film 32 was formed at 248 nm while introducing oxygen gas.

Next, an electron beam resist is formed at a film pressure of 1.0 μm in the same manner as in the first embodiment.
Drawing is performed in cm ² , and development is performed to obtain a resist pattern.

Using this resist pattern as a mask, Cl
Al and Al ₂ O exposed from the resist pattern by reactive ion etching using a mixed gas of O ₂ and O _{2
The three} films are sequentially removed. Finally, by removing the resist pattern, a phase shifter composed of the Al film 31 and the Al ₂ O ₃ film 32 as shown in FIG. 3B can be obtained.

A substrate coated with an i-line resist (PERIX500 (manufactured by Nippon Synthetic Rubber Co., Ltd.)) having a thickness of 1.3 μm was exposed to i-line of a mercury lamp through a projection exposure mask formed in this embodiment. / 5 reduction exposure (NA = 0.5, σ
= 0.6) to form a pattern. The exposure required at this time was 300 mJ / xm ² .

With respect to the line & space pattern, the focus margin was resolved at 0.35 μm pattern and the focus margin was reduced to 0 μm by the conventional exposure. It became possible to resolve at 0.9 μm. Regarding contact hole patterns,
It was confirmed that a 0.40 μm pattern which was not resolved by the conventional exposure was resolved at a focus margin of 1.5 μm. Also, by transferring using this mask and processing the substrate using the formed resist pattern as a mask,
It is possible to obtain a better processed shape.

Embodiment 5 Next, a fifth embodiment will be described.

This embodiment relates to a KrF-ray exposure mask formed by using Al and Al ₂ O ₃ . When Al is formed as a single layer semi-transparent by reactive sputtering, a desired translucent phase can be obtained by adjusting the flow rate of oxygen gas so as to provide an environment in which the composition ratio of oxygen element to Al element is about 1.43. It was confirmed that a shift film was obtained.

Considering that these conditions are formed by a two-layer film of Al and Al ₂ O ₃ , the respective molecular composition ratios are set to Al:
By setting Al ₂ O ₃ = 1: 10, a phase difference of 180 degrees and an amplitude transmittance of 15% with respect to the silicon oxide substrate can be obtained.

First, an Al film 31 having a thickness of 14 nm is formed on a silicon oxide substrate 10 by a sputtering method.
The Al ₂ O ₃ film 32 is removed by one while continuously introducing oxygen gas.
61 nm was created. Next, an electron beam resist was applied to a thickness of 1.
0 μm, and drawn with an electron beam at 6 μC / cm ² ,
Further development is performed to obtain a resist pattern.

Using this resist pattern as a mask, Cl
₂And O₂For reactive ion etching with mixed gas
Al film 31 and Al more exposed from the resist pattern
₂O ₃The film 32 is sequentially removed. And finally resist
The pattern is removed and the Al film 31 and Al₂O₃From membrane 32
Phase shifter can be obtained.

A KrF resist, referred to as XP8843 (manufactured by Shipley Co., Ltd.), having a thickness of 1.0 μm, was applied through the exposure mask thus formed to KrF.
Excimer laser 1/5 reduction exposure (NA = 0.4, σ = 0.
5) was performed to form a pattern. The exposure amount at this time was 40 mJ / cm ² . And 0.30 μm
The pattern that was resolved at the focus margin of 0 μm by using the pattern of the present embodiment can be changed to the focus margin by using the mask of this embodiment.
It was possible to resolve the image at a customer margin of 0.7 μm.

Also, regarding the contact hole pattern, a 0.30 μm pattern which was not resolved by the conventional exposure was used.
Was confirmed to be resolved at a focus margin of 1.2 μm.

Embodiment 6 Next, a sixth embodiment will be described.

This embodiment relates to a mask for i-line exposure made using Ti and TiO ₂ . When Ti is formed as a single-layer translucent film by reactive sputtering, a desired translucency can be obtained by adjusting the flow rate of oxygen gas so as to provide an environment in which the composition ratio of oxygen element to Ti element is about 0.61. It was confirmed that a phase shift film was obtained.

Considering that these conditions are formed with a two-layer film of Ti and TiO ₂ , the respective molecular composition ratios are Ti: T
By setting iO ₂ = 1: 0.43, a phase difference of 180 ° and an amplitude transmittance of 15.4% can be obtained with respect to the silicon oxide substrate.

First, as shown in FIG. 4A, a film having a thickness of 196 nm is formed on a silicon oxide substrate 10 by a sputtering method.
An m-th Ti film 41 is formed. Subsequently, a TiO ₂ film 42 was formed to a thickness of 84 nm while introducing oxygen gas.

Next, an electron beam resist is applied to a thickness of 1.0 μm.
Is formed at 6 μC / cm ² with an electron beam, and further developed to form a resist pattern. Using this resist pattern as a mask, Ti exposed from the resist pattern is formed by reactive ion etching using a fluorine-based gas.
The film 41 and the TiO ₂ film 42 are sequentially removed.

Finally, by removing the resist pattern, the Ti film 41 and the T film as shown in FIG.
A phase shift composed of the iO ₂ film 42 can be obtained.

A substrate coated with an i-line resist (PFRIX500 (manufactured by Nippon Synthetic Rubber Co., Ltd.)) having a thickness of 1.3 μm was exposed to i-line of a mercury lamp through a projection exposure mask formed in this embodiment. / 5 reduction exposure (NA = 0.5, σ
= 0.6) to form a pattern. The exposure required at this time was 300 mJ / cm ² .

Regarding the line & space pattern, the conventional exposure, which has been resolved at 0.35 μm pattern and focus margin = 0 μm, has been focused by the mask of this embodiment. It was possible to resolve with gin = 0.9 μm. Regarding the contact hole pattern, the 0.40 μm pattern which was not resolved by the conventional exposure
It was confirmed that the image was resolved at a focus margin of 1.5 μm. Further, by transferring the substrate using this mask and processing the substrate using the formed resist pattern as a mask, a better processed shape can be obtained.

The present invention is not limited to the above embodiments. For example, in each embodiment, the materials of the first translucent film and the second translucent film may be exchanged. Further, in the embodiment, two types of translucent films are used, but three or more types of translucent films may be used. Further, the same translucent film (two or more types) may be laminated plural times. In addition, without departing from the gist of the present invention,
Various modifications can be made.

Embodiment 7 FIG. 5 is a cross-sectional view showing a manufacturing process of an exposure mask substrate according to a seventh embodiment of the present invention. This exposure mask substrate is
a substrate for forming a g-line phase shift mask,
On a transparent substrate 60, an amorphous silicon film 61 is formed as a translucent film by a sputtering method, surface oxidation is performed to form a silicon oxide film 62, and a second amorphous silicon film 6 is further formed on the upper layer using silicon as a target.
3 is formed.

That is, first, as shown in FIG.
An amorphous silicon film 61 having a thickness of 59 nm is formed on a quartz substrate 60 having a thickness of 2.5 mm by a sputtering method. The refractive index n =
At 4.93, the amplitude transmittance for the quartz substrate was 17.4%.

Subsequently, as shown in FIG. 5B, the surface of the amorphous silicon film 61 is oxidized in a plasma containing an oxygen element to form a silicon oxide film 62.

Further, as shown in FIG.
A second amorphous silicon film 63 was deposited to a thickness of 59 nm by a sputtering method using silicon as a target.
The amplitude transmittance of the thus obtained two-layer film was 3.0% including the silicon oxide film. The substrate for the exposure mask is obtained in this manner. The thickness of the amorphous silicon film as the second translucent film has an amplitude transmittance of 5.0 including the first amorphous silicon film and the silicon oxide film.
%.

Next, a method of forming an exposure mask using this exposure mask substrate will be described.

First, as shown in FIG.
An electron beam resist 64 is formed to a thickness of 500 nm on the surface of the exposure mask substrate obtained in the steps shown in FIGS. 5A to 5C, and a coatable conductive film 65 is formed to a thickness of 200 nm. .

Next, as shown in FIG. 6B, drawing is performed by an electron beam using data including a device pattern and a region outside the device pattern, developed, and developed.
a is formed. Also in this case, the pattern is drawn with an electron beam from above the coatable conductive film 65, further developed, and a resist pattern is formed.
Forming a gate 64a. Here, the coating conductive film 65 is formed in order to prevent the charge-up of the electron beam when the resist 64 is insulative. B in the figure indicates the boundary between the pattern area and the non-pattern area.

Next, as shown in FIG. 6C, the second amorphous silicon film 63 exposed from the resist pattern is etched and removed by reactive ion etching using CF ₄ gas using the resist pattern as a mask. The gas was switched to etch the silicon oxide film 62 by reactive ion etching with a mixed gas of CF ₄ and O _2, and the gas was switched to CF ₄ to remove the first amorphous silicon film 61 by etching.

Thereafter, as shown in FIG. 6D, the resist pattern is removed.

After forming a phase shift pattern having a two-layer structure composed of the first amorphous silicon and the second amorphous silicon as shown in FIG. 6E, the electron beam resist 66 is formed to a thickness of 500 nm. Forming
Further, a coatable conductive film 67 is formed to have a thickness of 200 nm.

Next, as shown in FIG. 6 (f), drawing is performed by using an electron beam so as to leave a resist film in a region outside the device pattern, and development is performed to form a resist pattern 66a. Again, the coatable conductive film 67
An electron beam is drawn from above, and further developed to form a resist pattern 66a.

Next, as shown in FIG.
CF with distaste pattern as mask ₄Reactivity by gas
Etching the silicon oxide film 62 by ion etching
Second amorphous member in the pattern area as an operating stopper
The silicon film 63 is removed by etching.
The silicon nitride film 62 is removed by etching.

Finally, as shown in FIG. 6H, the resist pattern was removed.

The exposure mask thus formed is composed of a semi-transparent film having an amplitude transmittance of 17.4% made of only the first amorphous silicon film in the device pattern region.
Outside the device pattern region, the light shielding film has an amplitude transmittance of 3%.

Therefore, since the exposure light is shielded at least in the area outside the pattern area where the light reaches the wafer by transfer, the pattern becomes thin and the depth of focus becomes insufficient even when exposure is performed a plurality of times. Can be prevented.

Embodiment 8 In the above embodiment, the exposure mask for g-line was described, but here, the exposure mask for i-line will be described.

As in the case of the sixth embodiment shown in FIGS. 5A to 5C, a first substrate having a thickness of 80 nm is formed on a 2.5 mm-thick quartz substrate by sputtering in a nitrogen atmosphere. Silicon nitride film SiN _β (0.6 ≦
β ≦ 0.8). The refractive index of this silicon nitride film is n = 3.40, and the amplitude transmittance to the quartz substrate is 15.1.
%Met.

Subsequently, the surface of the silicon nitride film is oxidized in a plasma containing an oxygen element to form a silicon oxide film.

Further, a second silicon nitride film SiN _β (0.6 ≦ β ≦ 0.8) having a thickness of 80 nm is formed thereon by a sputtering method using silicon as a target.
The amplitude transmittance of the thus obtained two-layer film was 2.2% including the silicon oxide film. Note that a silicon film may be used instead of the second silicon nitride film.
The thickness of the second silicon nitride film or the silicon film may be any value as long as the amplitude transmittance of the two-layer film is 5% or less.

Next, a method for forming an exposure mask using this exposure mask substrate will be described.

First, as shown in FIGS. 6A to 6H, an electron beam resist is formed to a thickness of 500 nm on the exposure mask substrate obtained in the above step, The film 65 is formed to have a thickness of 200 nm.

Next, drawing is performed by an electron beam using data including a device pattern and a region outside the device pattern, and development is performed to form a resist pattern. Also in this case, a resist pattern is formed by drawing with an electron beam from the coatable conductive film, and further developing.

Next, after the second silicon nitride film exposed from the resist pattern is removed by reactive ion etching using a mixed gas of CF ₄ + O ₂ + N ₂ using the resist pattern as a mask, the gas is switched to CF ₄ and O by reactive ion etching using a mixed gas of _2, a first silicon nitride film is removed by etching with a mixed gas of switching the further gas etched CF 4 _{+ O} 2 ₊ N ₂ of the silicon oxide film, resist pattern - down Is removed.

After forming a two-layer phase shift pattern composed of the first and second silicon nitrides in this manner, an electron beam resist is formed to a thickness of 500 nm, and a coatable conductive film is formed to a thickness of 200 nm. It forms so that it may become.

Next, drawing is performed using data created so that a resist film remains in a region outside the device pattern by an electron beam, and development is performed to form a resist pattern.

Further, the second silicon nitride film in the pattern region is removed by reactive ion etching using a mixed gas of CF ₄ + O ₂ + N _{2 using} the resist pattern as a mask and the silicon oxide film as an etching stopper. Then, the silicon oxide film is removed by etching.

Finally, the resist pattern was removed.

The exposure mask thus formed is a translucent film having an amplitude transmittance of 15.1% made of only the first silicon nitride film in the device pattern region, and an amplitude transmittance of 2.15 outside the device pattern region. It is a 2% light shielding film.

In this case, as in the case of the seventh embodiment, the exposure light is shielded at least in the area outside the pattern area where the light reaches the wafer by transfer. Also, it is possible to prevent the pattern from becoming thin and the depth of focus from being insufficient.

Ninth Embodiment FIG. 7 is a sectional view showing a manufacturing process of an exposure mask substrate according to a ninth embodiment of the present invention. This exposure mask substrate is
a substrate for forming a phase shift mask for i-line,
A Cr film 71 is formed as a translucent film on a transparent substrate 70 by a sputtering method, a coated glass layer 72 is formed on the upper layer, and a Cr film 73 is formed on the upper layer by a sputtering method using Cr as a target. is there.

That is, first, as shown in FIG.
A first Cr film 71 having a thickness of 35 nm is formed on a quartz substrate 70 having a thickness of 2.5 mm by a sputtering method. The refractive index of the first Cr film 71 was n = 1.98, and the amplitude transmittance with respect to the quartz substrate was 20.2%.

Subsequently, as shown in FIG.
A coating glass 72 is formed on the film 71 with a thickness of 329 nm. At this time, the phase difference was set to 180 degrees in consideration of the respective phase differences between the Cr film and the coated glass.

Further, as shown in FIG. 7C,
A second Cr film 73 was deposited to a thickness of 35 nm by a sputtering method using Cr as a target. The amplitude transmittance of the thus obtained two-layer film was 4.0% including the coated glass film.

Next, a method of forming an exposure mask using the exposure mask substrate will be described.

First, as shown in FIG.
An electron beam resist 74 having a thickness of 500 nm is formed on the surface of the exposure mask substrate obtained in the steps shown in FIGS.

Next, as shown in FIG. 8B, drawing is performed by an electron beam using data including a device pattern and a region outside the device pattern, developed, and developed.
a is formed. Here, B in the figure indicates the boundary between the pattern region and the non-pattern region.

Next, as shown in FIG. 8C, the second Cr film 73 exposed from the resist pattern is etched and removed by reactive ion etching using CCl ₄ gas using the resist pattern as a mask. The silicon oxide film 72 is etched by reactive ion etching using a mixed gas of CF ₄ and O _2, and the gas is switched to CCl ₄ to form the first Cr film 7.
1 was removed by etching. Thereafter, as shown in FIG. 8D, the resist pattern is removed.

After forming a two-layer phase shift pattern 75 composed of the first Cr and the second Cr as shown in FIG. 8E, the electron beam resist 76 and the conductive film 77 are formed. It is formed with a thickness of 500 nm.

Next, as shown in FIG. 8 (f), drawing is performed by using data created so that a resist film remains in a region outside the device pattern by an electron beam, and development is performed to form a resist pattern 76a.

Then, as shown in FIG. 8 (g), the second Cr film in the pattern region is formed by reactive ion etching with CCl ₄ gas using the resist pattern as a mask and the coating glass 72 as an etching stopper. 73 is removed by etching, and the coated glass film 72 is further removed by etching.

Finally, as shown in FIG. 8H, the resist pattern was removed.

The exposure mask thus formed has a translucent film having an amplitude transmittance of 20.2% made of only the first Cr film in the device pattern area and an amplitude transmittance of 4% outside the device pattern area. It is a light shielding film.

Therefore, since the exposure light is shielded at least in the area outside the pattern area where the light reaches the wafer by the transfer, the pattern becomes thinner and the focal depth becomes insufficient even when the exposure is performed a plurality of times. Can be prevented.

Embodiment 10 Next, another exposure mask substrate will be described as a tenth embodiment of the present invention. In this example, the substrate is an exposure mask substrate on which a light shielding film can be formed outside the pattern region.
FIG. 9 is a sectional view showing a manufacturing process of the exposure mask substrate according to the tenth embodiment of the present invention. This exposure mask substrate is a substrate for forming an i-line phase shift mask, and a silicon nitride film SiN _0.681 is formed on a transparent substrate 80 as a translucent film serving as a phase shifter. A Cr film 82 is formed as a light shielding film, and an upper layer thereof is covered with a CrO film 83 as an antireflection layer.

That is, first, as shown in FIG.
Reactive sputtering is performed on a silicon oxide substrate 80 having a thickness of 2.5 mm in a nitrogen atmosphere with silicon as a target, and a uniform silicon nitride film SiN _0.6 having a thickness of 0.6 mol per mol of Si is formed. Deposit to a thickness of 75 nm. Here, the silicon nitride film SiN _0.6 has a light phase of 254 degrees in the film with respect to the i-line of the mercury lamp, and a light phase of
It is designed so that the phase is delayed by 0 degrees. This SiN
_The amplitude transmittance of the _0.6 film 81 with respect to the i-line was 3%.

[0138] Continuing the Cr film 82 as a light shielding film on the upper layer of thickness 75nm shown in FIG. 9 (b) silicon This nitride as shown in film SiN _0.6 81 formed by a sputtering method.

Then, as shown in FIG. 9C, a CrO film 83 was formed as an antireflection layer by a sputtering method using Cr as a target in an oxygen atmosphere.
m.

Next, an exposure mask is formed using this exposure mask substrate in the same manner as in the above-described example.

Embodiment 11 Next, another exposure mask substrate will be described as an eleventh embodiment of the present invention. This example is also an exposure mask substrate on which a light shielding film can be formed outside the pattern region.
This exposure mask substrate is a substrate for forming a KrF excimer laser phase shift mask and has a thickness of 2.5.
A silicon nitride film SiN _0.9 is formed as a semi-transparent film serving as a phase shifter on a silicon oxide substrate having a thickness of 0.2 mm, a Cr film is formed thereon as a light-shielding film, and the upper layer is formed of a CrO film as an anti-reflection layer. It is characterized by being coated.

That is, first, on a 2.5 mm-thick silicon oxide substrate, reactive sputtering is performed in a nitrogen atmosphere with silicon as a target, and a uniform silicon nitride film SiN _{0 having} a nitrogen concentration of 0.9 mol per mol of Si. _.9 is deposited to a thickness of 80 nm. Here, the silicon nitride film SiN _0.9 has a light phase of 296 degrees in the film with respect to the light of 248 nm of the KrF excimer laser, and is 80 nm.
Is designed such that the phase of light traveling in the air is delayed by 180 degrees with respect to the phase of 116 degrees. K of this SiN _{0. 9} film
The amplitude transmittance of the rF excimer laser for light of 248 nm was 4%.

Subsequently, this silicon nitride film SiN _0.9
A Cr film having a thickness of 79 nm is formed as a light shielding film on the upper layer by a sputtering method.

Further, on top of this, C
A 30 nm CrO film was deposited as an anti-reflection layer by sputtering using r as a target.

Here, the same result as that of the twelfth embodiment is obtained except that the conductive film SnO is interposed between SiN and Cr.

Embodiment 12 Next, another exposure mask substrate will be described as a twelfth embodiment of the present invention. This example is also an exposure mask substrate on which a light shielding film can be formed outside the pattern region.
This exposure mask substrate is a substrate for forming a KrF excimer laser phase shift mask and has a thickness of 2.5.
A silicon nitride film SiN _1.8 is formed as a translucent film serving as a phase shifter on a silicon oxide substrate having a thickness of 2 mm, a Cr film is formed thereon as a light shielding film, and the upper layer is formed of a CrO film as an anti-reflection layer. It is characterized by being coated.

That is, first, on a 2.5 mm-thick silicon oxide substrate, reactive sputtering was performed in a nitrogen atmosphere with silicon as a target, and a uniform silicon nitride film SiO _{1 of} 1.8 mol oxygen to 1 mol Si was used. _.8 is deposited to a thickness of 94 nm. Here, the silicon nitride film SiO _1.8 has a light phase of 355 degrees within the film of 248 nm of the KrF excimer laser and is 94 nm.
Is designed such that the phase of light traveling in the air is delayed by 180 degrees with respect to the phase of 175 degrees. K of this SiO _{1. 8} film
The amplitude transmittance of the rF excimer laser for light of 248 nm was 4%.

Subsequently, the silicon nitride film SiO _1.8
A Cr film having a thickness of 70 nm is formed as a light shielding film on the upper layer by a sputtering method.

Further, on top of this, C was added in an oxygen atmosphere.
A 30 nm CrO film was deposited as an anti-reflection layer by sputtering using r as a target.

Embodiment 13 Next, another exposure mask substrate will be described as a thirteenth embodiment of the present invention. This example is also an exposure mask substrate on which a light shielding film can be formed outside the pattern region.
This exposure mask substrate is a substrate for forming a phase shift mask for i-line of a mercury lamp, and has a thickness of 2.5 mm.
A silicon nitride film SiN _0.6 is formed as a translucent film serving as a phase shifter on the silicon oxide substrate, and SnO is deposited thereon as a conductive film to a thickness of 10 nm, and then a Cr film is formed as a light shielding film. Is coated with a CrO film as an antireflection layer.

First, on a 2.5 mm-thick silicon oxide substrate, reactive sputtering is performed in a nitrogen atmosphere with silicon as a target, and a uniform silicon nitride film SiN ₀ having 1.8 moles of nitrogen per mole of Si. _.6 is deposited to a thickness of 75 nm. Here, the silicon nitride film SiN _0.6 has a light phase of 254 in the film with respect to the i-line.
It is designed so that the phase of light traveling in air of 75 nm is delayed by 180 degrees with respect to the phase of 74 degrees. This S
The amplitude transmittance for the i-line of the iN _0.6 film was 3%. Subsequently, a 10 nm thick SnO film was formed as a conductive film on the silicon nitride film SiN _0.6 by sputtering.
After the deposition, a 70 nm-thick Cr film is formed as a light-shielding film by a sputtering method.

Further, on top of this, C
A 30 nm CrO film was deposited as an anti-reflection layer by sputtering using r as a target.

This conductive film SnO is formed directly on a transparent substrate, and a silicon nitride film is formed thereon to produce the same result as in the thirteenth embodiment.

Embodiment 14 Next, another exposure mask substrate will be described as a fourteenth embodiment of the present invention. This example is also an exposure mask substrate on which a light shielding film can be formed outside the pattern region.
This exposure mask substrate is made of a KrF excimer laser.
A substrate for forming an 8 nm optical phase shift mask, a silicon nitride film SiN _0.9 as a translucent film serving as a phase shifter on a 2.5 mm thick silicon oxide substrate.
Is formed to a film thickness of 80 nm, and S
After depositing nO to a thickness of 10 nm, C
An upper layer is formed of Cr as an anti-reflection layer.
It is characterized by being coated with an O film.

First, on a 2.5 mm-thick silicon oxide substrate, reactive sputtering is performed in a nitrogen atmosphere with silicon as a target, and a uniform silicon nitride film SiN _{0 of} 0.9 mol of nitrogen per mol of Si. _.9 is deposited to a thickness of 80 nm. Here, the silicon nitride film SiN _0.9 has a light phase of 296 degrees in the film with respect to the light of 248 nm of the KrF excimer laser, and is 80 nm.
Is designed such that the phase of light traveling in the air is delayed by 180 degrees with respect to the phase of 116 degrees. K of this SiN _{0. 9} film
The amplitude transmittance of the rF excimer laser for light of 248 nm was 4%.

Subsequently, the silicon nitride film SiN _0.9
After depositing 8 nm of SnO by sputtering as a conductive film on the upper layer, a Cr film having a thickness of 70 nm is formed by a sputtering method as a light shielding film.

Further, on top of this, C was added in an oxygen atmosphere.
A 30 nm CrO film was deposited as an anti-reflection layer by sputtering using r as a target.

Embodiment 15 Next, another exposure mask substrate will be described as a fifteenth embodiment of the present invention. This example is also an exposure mask substrate on which a light shielding film can be formed outside the pattern region.
This exposure mask substrate is a substrate for forming a phase shift mask for i-line of a mercury lamp, and has a thickness of 2.5 mm.
Of SnO as a conductive film on a silicon oxide substrate of
After depositing nm, a two-layer film of a silicon oxide film SiO ₂ and a silicon film is formed as a translucent film serving as a phase shifter, and then a Cr film is formed thereon as a light-shielding film. Characterized in that it is covered with a CrO film.

That is, first, 10 nm of SnO was deposited on a 2.5 mm thick silicon oxide substrate by sputtering.
Then, a silicon oxide film having a thickness of 150 nm is formed thereon by a CVD method, and then a silicon film having a thickness of 37 nm is formed by a sputtering method. Here, the light transmitted through the two-layer film is designed so that the phase of the light in the film is 364 degrees with respect to the i-line, and the phase of the light traveling in the air of 187 nm is 180 degrees behind the phase of 184 degrees. ing. This 2
The amplitude transmittance of the layer film with respect to the i-line was 2.5%.

Subsequently, a Cr film having a thickness of 70 nm is formed as a light shielding film on the two-layer film by a sputtering method.

Further, on top of this, C
A 30 nm CrO film was deposited as an anti-reflection layer by sputtering using r as a target.

Although the conductive film SnO is formed directly on the transparent substrate, it may be formed on a two-layer film.

Embodiment 16 Next, an exposure mask is formed using this exposure mask substrate in the same manner as in the above-described example. Here, the first embodiment is used.
The substrate for the exposure mask prepared in 1 is used. This exposure mask substrate is a substrate for forming a phase shift mask for a KrF excimer laser, and is formed on a silicon oxide substrate 90 having a thickness of 2.5 mm as a semi-transparent film serving as a phase shifter _{. 9} 91 is formed, it is configured by covering the upper layer further forms a Cr film 92 as a light shielding film in the upper layer in the CrO film 93 as an antireflection layer.

First, as shown in FIG. 10A, an electron beam resist 94 is formed to a thickness of 500 nm on the surface of an exposure mask substrate, and a coatable conductive film 95 is formed to a thickness of 200 nm.

Next, as shown in FIG. 10B, drawing is performed with an electron beam at 4 μC / cm ^{2 using} a device pattern and data including a region outside the device pattern, and developed to form a resist pattern 94a. Also in this case, the resist pattern 94a is formed by drawing with an electron beam from the coatable conductive film 95 and further developing. B in the figure indicates the boundary between the pattern area and the non-pattern area.

Then, as shown in FIG. 10C, the Cr film and the CrO film exposed from the resist pattern are removed by reactive ion etching with Cl ₂ gas using the resist pattern as a mask. Switching silicon nitride film Si exposed by reactive ion etching with a mixed gas of CF ₄ and O ₂
N _0.991 is removed by etching.

Thereafter, as shown in FIG. 10D, the resist pattern is removed with a mixed solution of sulfuric acid and hydrogen peroxide solution. As a result, a phase shift pattern including a light-shielding film and a translucent film is formed. At this time, an alignment mark M for performing exposure for removing an unnecessary light-shielding film is formed at the same time.

After forming a phase shift pattern comprising a light-shielding film and a translucent film as shown in FIG. 10E, an electron beam resist 96 is formed to a thickness of 500 nm.
Further, a coatable conductive film 97 is formed to have a thickness of 200 nm.

Next, as shown in FIG. 10 (f), drawing is performed with an electron beam at 4 μC / cm ^{2 using} data created so that a resist film remains in a region outside the device pattern, and developed to form a resist pattern 96a. . Also in this case, the resist pattern 96a is formed by drawing an electron beam on the coatable conductive film 97 and further developing the resist pattern 96a.

[0170] Then, as shown in FIG. 10 (g), the resist pattern - by reactive ion etching using Cl ₂ gas in as a mask, CrO film 93 / Cr film 92
Is removed by etching.

Finally, as shown in FIG. 10H, the resist pattern was removed with a mixed solution of sulfuric acid and hydrogen peroxide.

The exposure mask thus formed is a translucent film composed of a two-layer film of silicon nitride and silicon in the device pattern region, and a light-shielding film including a Cr film outside the device pattern region.

Therefore, since the exposure light is shielded at least in the area outside the pattern area where the light reaches the wafer by the transfer, the pattern becomes thinner and the depth of focus becomes insufficient even when the exposure is performed a plurality of times. Can be prevented.

Embodiment 17 In the above embodiment, a case was described in which both a translucent film as a phase shift layer and a light-shielding film were used as the exposure mask substrate. A method for forming a phase shift layer pattern after forming a light-shielding film pattern outside a frame portion, that is, a pattern region, using an exposure mask substrate on which a CrO film 93 is formed.

First, as shown in FIG. 11A, a Cr film 92 and a Cr film 92 are formed on a silicon oxide substrate 90 having a thickness of 2.5 mm.
An electron beam resist 94 is formed to a thickness of 500 nm on the exposure mask substrate on which the O film 93 is formed, and a coatable conductive film 95 is formed to a thickness of 200 nm.

Next, as shown in FIG. 11B, drawing is performed by an electron beam using data for forming an alignment mark M and a light-shielding film in a region outside the device pattern, and developed to form a resist pattern. Also in this case, a resist pattern is formed by drawing an electron beam from the coatable conductive film and further developing the resist.

Next, as shown in FIG. 11C, the CrO / Cr film exposed from the resist pattern is etched away by reactive ion etching with Cl ₂ gas using the resist pattern as a mask, and the resist pattern is removed. Remove.

After forming the alignment marks M and the light-shielding film in the region outside the device pattern in this manner, FIG.
As shown in FIG. 1 (d), reactive sputtering is performed in a nitrogen atmosphere using silicon as a target, and a uniform silicon nitride film SiN of 0.6 mol of nitrogen per mol of Si is formed.
_0.6 is deposited to a thickness of 75 nm. Here, the silicon nitride film SiN _0.6 has a light phase of 254 degrees in the film with respect to the i-line of the mercury lamp, and has a phase of 180 degrees behind the phase of light traveling in air of 75 nm of 74 degrees. Designed. The amplitude transmittance of the SiN _0.6 film 91 with respect to the i-line was 3%.

Then, as shown in FIG. 11E, an electron beam resist 96 is formed to a thickness of 500 nm, and a coatable conductive film 97 is formed to a thickness of 200 nm.

Next, as shown in FIG. 11 (f), drawing is performed by using an electron beam and data created so that the device pattern and the region outside the device pattern remain, and developed to form a resist pattern.

[0181] Further, as shown in FIG. 11 (g), the resist pattern - by reactive ion etching using a mixed gas of _CF 4 + _{O 2} the emissions as a mask, SiN _0.6
The film 91 is etched.

Finally, as shown in FIG. 11H, the resist pattern was removed.

The exposure mask thus formed is a translucent film made of only a silicon nitride film in the device pattern region and a light-shielding film outside the device pattern region as in the case of the sixteenth embodiment.

In this case as well, since the exposure light is shielded at least in the area outside the pattern area where the light reaches the wafer by transfer, the pattern narrows and focuses even when exposure is performed a plurality of times. Insufficient depth can be prevented.

The present invention is not limited to the embodiments described above. Further, in the embodiment, two types of translucent films are used, but three or more types of translucent films may be used. Further, the same translucent film (two or more types) may be laminated plural times. In addition, various modifications can be made without departing from the scope of the present invention.

[0186]

As described above, according to the present invention,
For a pattern composed of a plurality of translucent films used for an exposure mask, by including at least one kind of the same element in each film, the process is simplified and the phase shift effect is maximized. It becomes possible by realizing an exposure mask that can be used.

According to the present invention, the transmittance is set to 5% or less outside the pattern region in order to prevent light transmitted to the outside of the pattern region by light transmitted through the translucent film. Thus, a highly reliable pattern can be formed without pattern thinning.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of an exposure mask according to a first embodiment.

FIG. 2 is a sectional view showing a manufacturing process of an exposure mask according to a third embodiment.

FIG. 3 is a sectional view showing a manufacturing process of an exposure mask according to a fourth embodiment.

FIG. 4 is a sectional view showing a manufacturing process of an exposure mask according to a sixth embodiment.

FIG. 5 is a sectional view showing a manufacturing process of a substrate for an exposure mask according to a seventh embodiment.

FIG. 6 is a sectional view showing a manufacturing process of an exposure mask using the exposure mask substrate of the seventh embodiment.

FIG. 7 is a sectional view showing a manufacturing process of an exposure mask substrate according to an eighth embodiment.

FIG. 8 is a sectional view showing a manufacturing process of an exposure mask using the exposure mask substrate of the eighth embodiment.

FIG. 9 is a sectional view showing a manufacturing process of the exposure mask substrate according to the tenth embodiment.

FIG. 10 is a sectional view showing a manufacturing process of an exposure mask according to a sixteenth embodiment.

FIG. 11 is a sectional view showing a manufacturing process of the exposure mask of the seventeenth embodiment.

FIG. 12 is a characteristic diagram showing a range of optical constants to be satisfied when forming a single layer film of a translucent film pattern and actual measured values of the optical constants;

FIG. 13 is a characteristic diagram showing a range of optical constants to be satisfied when forming a semi-transparent film pattern single layer film and actual measured values of the optical constants.

FIG. 14 is a characteristic diagram showing a range of optical constants to be satisfied when forming a semi-transparent film pattern single layer film and actual measured values of the optical constants.

FIG. 15 is a characteristic diagram showing the relationship between the refractive index and the extinction coefficient of Cr—CrO ₂ .

FIG. 16 is a characteristic diagram showing a relationship between a refractive index and an extinction coefficient in Al—Al ₂ O ₃ ;

FIG. 17 is a characteristic diagram showing a relationship between a refractive index and an extinction coefficient in Ti—TiO.

FIG. 18 is a characteristic diagram showing a relationship between a refractive index and an extinction coefficient in GaAs-GaAsO.

FIG. 19 is a sectional view showing the structure of an ideal halftone phase shift film.

FIG. 20 is a view showing a pattern outside a pattern region and an exposure state when exposure is performed using a conventional halftone phase shift film.

FIG. 21 is a diagram showing a state of a pattern area after exposure when exposure is performed using a conventional halftone phase shift film.

[Explanation of symbols]

10 ... light transmitting substrate, 11 ... silicon film, 12 ... _Si 3 _{N 4} film, 13 ... resist, 14 ... conductive film, 21 ... Cr film, 22 ... CrO ₂ film, 31 ... Al film, 32 ... Al ₂ O ₃ film, 41 Ti film, 42 TiO film, 60 quartz substrate 61 amorphous silicon film 62 silicon oxide film 63 second amorphous silicon film 64 resist 65 coatable conductive film 66 electron beam resist 67 ... Coatable conductive film 70 ... Quartz substrate 71 ... Cr film 72 ... Coated glass layer 73 ... Cr film 74 ... Electron beam resist 80 ... Transparent substrate 81 ... Silicon nitride film 82 ... Cr film 83 ... CrO film 90 ... Silicon oxide substrate 91 ... Silicon nitride film 92 ... Cr film 93 ... CrO film 94 ... Electron beam resist 95 ... Coatable conductive film 96 ... Electron beam resist 97 ... Coatable conductive film

Claims (5)

[Claims] 1. A single light-transmitting substrate having a phase difference from a transparent portion of the light-transmitting substrate that is different within a range of 180 ± 10 degrees and adjusted to have an amplitude transmittance of 10 to 40%. A semi-transparent pattern composed of a semi-transparent layer or at least one semi-transparent layer and a multilayer first semi-transparent film of a transparent layer; and further laminated on a partial region of the translucent pattern, and the amplitude of the region An exposure mask, comprising: a light-shielding layer adjusted to have a transmittance of 5% or less or a second translucent film having an amplitude transmittance of 10 to 40%. 2. The exposure mask according to claim 1, wherein the partial region includes at least a peripheral region outside a region that contributes as a semiconductor element when transferred onto a wafer. 3. A method of forming a resist pattern, comprising exposing a substrate coated with a resist through the exposure mask according to claim 1 to form a resist pattern. 4. A single layer on a light-transmitting substrate, which is adjusted so that a phase difference from a transparent portion of the light-transmitting substrate is different within a range of 180 ± 10 degrees and an amplitude transmittance is 10 to 40%. Forming a first translucent film composed of a translucent film layer or at least one translucent layer and a transparent layer; and further laminating the whole or part of the first translucent film, A method of forming a light-shielding layer or a second translucent film having an amplitude transmittance of 10 to 40% adjusted so that the amplitude transmittance is 5% or less. An oxide film, a nitride film, a hydrogenated film, between the first translucent film and the second translucent film in processing the light-shielding layer or the second translucent film having an amplitude transmittance of 10 to 40%; Forming a third film made of either a carbonized film or a halogenated film Method of manufacturing an exposure mask substrate, characterized by comprising a. 5. A single light-transmitting substrate having a phase difference from a transparent portion of the light-transmitting substrate different in a range of 180 ± 10 degrees and adjusted to have an amplitude transmittance of 10 to 40%. A first translucent film forming step of forming a first translucent film composed of at least one translucent layer or at least one translucent layer and a transparent layer, and a third translucent film on the first translucent film. A third film forming step of forming a film, and further thereon, a light-shielding layer adjusted so that the overall amplitude transmittance is 5% or less or a second translucent film having an amplitude transmittance of 10 to 40%. A second semi-transparent film forming step of forming a mask, and an etching step of selectively removing the second semi-transparent film using the third film as an etching stopper. Method.