JPH0683034A - Exposure, mask, exposure mask substrate and its production - Google Patents

Abstract

PURPOSE:To provide a highly accurate exposure mask and its production by which plural semitransparent films can be easily formed without defects or deposition of dust and the production process can be simplified. CONSTITUTION:This exposure mask has a mask pattern formed on a light- transmitting substrate. The mask pattern contains a semitransparent film pattern in which the optical length for the exposure light differs from that in the transparent part of the light-transmitting substrate 10 by a specified amount. This semitransparent film pattern consists of laminated layers of a Si layer 11 and a Si2N4 layer 12, each having the optimum film thickness. These layers contain the same element (Si) but have different compsn.

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 optical lithography technology, and more particularly to a semitransparent film pattern.
The present invention relates to an exposure mask in which a phase shifter including a mask is formed, an exposure mask substrate, and a method for manufacturing the exposure mask.

[0002]

2. Description of the Related Art In recent years, semiconductor integrated circuits have been highly integrated and miniaturized. In the manufacture of such semiconductor integrated circuits, the lithography technique is particularly important as a cornerstone of processing.

In the current lithographic technology, a method of projecting and exposing a mask pattern onto an LSI substrate through a reduction optical system is mainly used. However, 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. 0.5
Direct patterning technology using KrF excimer laser or electron beam and X-ray same-magnification exposure technology are being developed for pattern dimensions of less than μm, but for reasons of mass productivity and process versatility, etc. , Expectations for photolithography are very high.

Under these circumstances, g
The use of various light sources such as X-ray, i-line, excimer laser, X-ray, etc. is being considered, development of new resists and new resist treatments such as REL are also being considered, and further multi-layer resist process. , CEL, image reversal method, etc. are also being studied.

On the other hand, recently, attempts have been made to miniaturize the exposure light source without changing it. As one method,
There is a phase shift method. The phase shift method is intended to improve the pattern accuracy by providing a phase inversion layer in the light transmitting portion to eliminate the influence of the diffraction of light from the 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. This method is difficult to be effective when three or more patterns are adjacent to each other. That is, the optical phase difference between the two patterns is set to 18
If it is 0 degree, the other pattern will be in phase with one of the previous two patterns. As a result, the phase difference 18
Patterns with 0 degrees resolve each other, but patterns with 0 degree phase difference
However, there is a problem that they are not resolved. In order to solve this problem, it is necessary to fundamentally rethink the device design, and it is quite difficult to put it into practical use immediately.

Therefore, there is a halftone phase shift mask as a method which uses the phase shift method and does not require a device design change. In order to maximize the effect of this 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 of these films (complex refractive index n-ik: i is a unit imaginary number) and the film thickness. That is, in order to obtain a desired phase difference and 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 monolayer film.

FIG. 19 shows the structure of an ideal halftone phase shift film. The mask formed by this method includes a light-transmissive portion 1a and a light-semitransmissive film 1 on a light-transmissive substrate 1.
b is formed, 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 purposes
The light-semitransmissive film 1b is configured by a two-layer structure including the second layer 3 and the second layer 3 which adjusts the phase difference caused by the first layer 2 to be 180 degrees in total.

As described above, in the conventional halftone phase shift mask, the halftone portion has a two-layer structure, the first layer 2 adjusts the amplitude transmittance, and the second layer 3 the second layer structure. The temperature is adjusted so as to be 180 ° C. together with the phase difference caused by the layer 2 of No. 1, but as a material used for these layers, conventionally, Cr, MoSi or the like was used for the first layer, and for the second layer, SiO ₂ , M
gF ₂ , CaF ₂ , Al ₂ O _3, etc. are used. Therefore, in order to form the halftone portion, it is necessary to form the film in two different environments. For example, there is a method of forming a Cr film by using a sputtering apparatus for forming the first film and forming a SiO ₂ film by using a CVD method for forming the _second film.

However, in this type of method, the film formation is
Since the processes are performed separately, there is a problem in that dust is attached during transportation and defects are increased. Also, in processing, since the elements to be processed are different, a plurality of different gases (for example, when a semitransparent film is composed of a Cr / SiO ₂ film, Cr is a chlorine-based gas and SiO ₂ is a fluorine-based gas). There is a problem that etching must be performed by using (processing with gas). Further, although the transparent film is used for the second layer, the transparent film has a small refractive index, so that the film thickness of the phase shifter becomes large. Therefore, there is also a problem that processing accuracy is poor.

Further, in the exposure step, in order to prevent the exposure light from leaking from the alignment or inspection marks existing in areas other than the pattern area on the mask, a blind is provided in the projection exposure apparatus to cut off the light outside the pattern area. ing. Since the image of the blind causes a blur of the image of about 100 μm on the wafer, it does not serve to divide the pattern area on the wafer. For this reason, conventionally, as shown in FIG. 20A, the light shielding pattern 101 is formed on the mask so as to cover the outer periphery of the pattern region. However, when the exposure mask is formed only by the semi-transparent film, the semi-transparent mask is used as shown in FIG. 20 (b) instead of the light-shielding pattern existing in the peripheral area outside the pattern area, which is conventionally intended to divide the pattern area. The pattern 201 will be used. At this time, the light passing through the semitransparent film existing at the boundary of the pattern area is
Transmittance of translucent film for adjacent patterns on wafer ×
Only the amount of exposure will be applied. For this reason, as shown in FIG. 21, in the irradiation region, there is a problem that the exposure amount is substantially excessive and the pattern region is thinned and the depth of focus is insufficient.

[0012]

As described above, the conventional method
In the case of the hood type phase shift mask, there are problems that the number of steps is increased in forming the semi-transparent film, and the adhesion of dust and the generation of defects occur, and it is difficult to maximize the phase shift effect. there were.

Further, when the exposure mask is formed only by the semitransparent film, the semitransparent pattern is used even in the peripheral area outside the pattern area, which is conventionally intended to divide the pattern area, and therefore, it exists at the boundary of the pattern area. The light passing through the semi-transparent film irradiates the adjacent pattern on the wafer by the transmittance of the semi-transparent film × exposure amount. Therefore, in the irradiation region, there is a problem that the exposure amount is substantially excessive and the pattern region is thinned, and further, the depth of focus is insufficient.

The present invention has been made in view of the above circumstances, and an object thereof is to easily laminate a plurality of semi-transparent films without inviting dust and causing defects. An object of the present invention is to provide an exposure mask capable of simplifying the steps and maximizing the phase shift effect, and a manufacturing method thereof.

Further, the present invention provides an exposure mask which does not have a problem that the pattern area is thinned or the depth of focus is insufficient even when the exposure mask is formed only by a semitransparent film. With the goal.

[0016]

In order to solve the above problems, the present invention employs the following configurations.

That is, a first aspect of the present invention is an exposure mask in which a mask pattern is formed on a transparent substrate, wherein the mask pattern has an optical path length for the exposure light which is different from the transparent portion of the transparent substrate. The semi-transparent film pattern is configured so as to be different in a fixed amount, and the semi-transparent film pattern is characterized by being formed by laminating layers having different compositions containing the same element.

A second aspect of the present invention is an exposure mask in which a mask pattern is formed on a translucent substrate, the mask pattern including a semitransparent film whose optical path length for exposure light differs from that of a transparent portion by a predetermined amount. In the manufacturing method of 1, the layers having different compositions containing the same element are sequentially laminated as the semitransparent film. Here, when sequentially laminating layers having different compositions containing the same element, a sputtering method using a target, a vapor deposition method, a CVD method formed by sequentially switching different gases containing the same element, or the like is used. .

The following are preferred embodiments of the present invention.

(1) The semitransparent film is made of silicon, a silicon compound, a mixture containing silicon, germanium, a germanium compound, a mixture containing germanium, or Cr, A.
l, Ti, Sn, In, Cd or other metal elements, metal compounds and oxides, nitrides, hydrides, carbides and halides of which at least one or more kinds are mixed and the composition ratio of the mixture is controlled. Consist of layers.

(2) At least one of a plurality of translucent films
One layer is formed by sputtering, and the composition ratio of nitrogen, oxygen or halogen elements is controlled by mixing a gas such as nitrogen gas, oxygen gas, hydrogen gas, acetylene or a gas containing halogen elements into the atmosphere. To form another layer while adjusting the amplitude transmittance.

(3) Including a modification step of finely adjusting the amplitude transmittance by changing the crystal state by a step of ion implantation or a heat treatment step on the surface of the formed semi-transparent film pattern.

According to a third aspect of the present invention, in an exposure mask in which a mask pattern is formed on a transparent substrate, the mask pattern has an optical path length with respect to exposure light which is a predetermined amount from the transparent portion of the transparent substrate. It is characterized in that it includes a semi-transparent film pattern configured differently, and a semi-transparent film or a light-shielding film is further partially or entirely laminated on the semi-transparent film pattern.

That is, the exposure mask of the present invention has a phase difference of 18 with respect to the transparent portion of the transparent substrate on the transparent substrate.
Different in the range of 0 ± 10 degrees and amplitude transmittance of 10 to 40
%, A semi-transparent pattern of a single semi-transparent layer or a multi-layer first semi-transparent film consisting of at least one semi-transparent layer and a transparent layer, and a part of the semi-transparent pattern And a light-shielding layer adjusted to have an amplitude transmittance of 5% or less or a second semi-transparent film having an amplitude transmittance of 10 to 40%. .

Preferably, the part of the region includes at least the outer peripheral region of the region that contributes as a semiconductor element when transferred onto the wafer.

Desirably, the first phase-shifting layer is formed.
The semitransparent film and the second semitransparent film formed on the phase shift have the same composition.

Further, desirably, the first semitransparent film forming the phase shift layer and the second semitransparent film formed on the phase shift contain at least the same element.

It is desirable that this laminated area is outside the area to be transferred onto the wafer. The first here
The semitransparent film pattern is a semitransparent film pattern single layer in which the refractive index n and the extinction coefficient k are adjusted so that the optical path length for exposure light differs from the transparent portion of the transparent substrate by a predetermined amount. Alternatively, one layer may adjust only the refractive index n and the other layer may adjust the extinction coefficient k.

In the fourth exposure mask substrate of the present invention, the phase difference between the transparent substrate and the transparent portion of the transparent substrate is:
A single semi-transparent layer or a multi-layer first semi-transparent film composed of at least one semi-transparent layer and a transparent layer, which are different in the range of 180 ± 10 degrees and are adjusted to have an amplitude transmittance of 10 to 40%. And a light-shielding layer or an amplitude transmittance of 10 to 4 which is further entirely or partially laminated on the first semitransparent film and adjusted so that the amplitude transmittance of the area is 5% or less.
0% of the second semitransparent film and the oxide film, the nitride film, the hydroxide film, the carbide film or the halogenated film interposed between the first semitransparent film and the second semitransparent film And a third film made of any of the above.

In the fifth exposure mask manufacturing method of the present invention, the phase difference between the transparent substrate and the transparent portion of the transparent substrate is different in the range of 180 ± 10 degrees, and the amplitude transmittance is different. 1
A single-layer or multi-layer first translucent film adjusted to 0 to 40% is formed, and a third translucent film is formed on the first translucent film.
And a second light-transmissive film having an amplitude transmittance of 10 to 40% or a light-shielding layer adjusted so that the overall amplitude transmittance is 5% or less.
An etching step of selectively removing the second semitransparent film by using the film formed in the third film forming step as an etching stopper is included. The third film is a conductive film, an oxide film, a hydroxide film, a nitride film, a carbide film or a halogenated film.

Preferably, a conductive film is interposed between the phase shift layer and the semitransparent layer or the light shielding layer.

Desirably, the oxide film is formed by natural oxidation, by plasma containing an oxygen element, or by oxidation by immersing in an oxidizing solution.

[0033]

According to the present invention, since the semitransparent film is formed of at least two layers and some of the elements of each layer are made common, the semitransparent film can be produced by the same apparatus, and the pattern can be formed. -It is possible to etch with the same type of etchant during polishing. Therefore, it is possible to simplify the process for forming the semitransparent film. Further, even if the composition of a single layer that obtains a desired amplitude transmittance and phase difference as a semitransparent film is known, it may be difficult to realize a substance having that composition. At this time, if the composition of the single layer is set to be equal to the composition of the plurality of layers having partially different compositions, a stable plurality of layers that can be easily formed, and as a result, a layer equivalent to the single layer is formed. can do. That is,
By forming the semitransparent film with a plurality of types 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, the exposure light is shielded in the mask including the semi-transparent pattern, at least in the area outside the pattern area where the light reaches the wafer by transfer. It is possible to prevent thinning and lack of depth of focus. For example, in the exposure result for a positive resist using a semi-transparent mask for i-line having an intensity transmittance of 2%, a pattern of a 0.55 μm line-and-space pattern modified to a desired size with an appropriate exposure amount is further exposed. B. The pattern dimension is 0.49 μm, which is about 10% smaller than the desired value, by irradiating once with light corresponding to the intensity transmittance of the mask.
However, according to the above configuration, the exposure light can be blocked at least in the area outside the pattern area where the light reaches the wafer by transfer. The semitransparent film for light shielding can be used not only in the outside of the pattern region but also in the pattern region. That is, when the resist pattern on the wafer formed by the semi-transparent mask pattern by a plurality of exposures causes a remarkable film thickness phenomenon, the semi-transparent film may be laminated in the region excluding the edge portion of the semi-transparent pattern. It is possible to reduce the film thickness of the resist pattern.

According to the fourth aspect of the present invention, the oxide film or the conductive film is interposed between the first semitransparent film and the second semitransparent film which form the phase shift layer. Since the oxide film or the conductive film acts as an etching stopper, it can be selectively removed while maintaining the phase shift layer in a good condition, so that a good exposure mask without pattern thinning or lack of depth of focus can be easily performed. Can be formed.

Further, when an oxide film is used, it is only necessary to carry out surface oxidation in the same chamber, and the formation is extremely easy.

Furthermore, when a conductive film is used, it becomes possible to prevent charge-up.

According to the sixth aspect of the present invention, the third aspect of the hydroxide film, the nitride film, the carbide film, the halogenated film, the oxide film, the conductive film, etc.
Since this film acts as an etching stopper, it can be selectively removed while keeping the phase shift layer in a good state, and it is possible to easily form a good exposure mask without pattern thinning and lack of depth of focus. Becomes

[0039]

First, the basic principle of the present invention will be described before describing the embodiments.

When the semi-transparent film is used as a single layer, it is necessary to control the phase of light passing through the semi-transparent film at 180 ° ± 10% with respect to the phase of light passing through the transparent portion.
In addition, it is necessary to set the transmittance of the semitransparent film to a desired value. This value of ± 10% shifts the phase difference from 180 degrees by simulation, and the range where the deterioration of the depth of focus is within 10% is 180 degrees ± 10%.
It is decided based on the degree.

In order to obtain the maximum resolution with the phase shift mask of the semitransparent film, the optical constant of the semitransparent film needs to satisfy the following conditions. If 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 semitransparent film region is E2, the relationship between them is E1 = t1 · E0 … (1) E2 = t2 · E0 …… (2). However, 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) However, E1 = | E1 | exp (δ1) E2 = | E2 | exp (δ2). The light amplitude transmittances t1 and t2 of the semitransparent film region and the transmissive region in the equations (1) and (2) are the reflectivity, the transmittance and the film of the interface between the substance forming these regions and another medium. It can be easily obtained by considering the multiple reflection in the film thickness T of the substance in consideration of the absorbance. The reflectance and the transmittance of a substance are obtained from the refractive index n and the extinction coefficient k. The absorbance of the film can be calculated from the extinction coefficient k.

By the way, since the translucent film in question is a phase shifter layer, considering the phase difference of 180 ° with respect to the aperture, the film thickness T is T = λ / 2 (n- 1)… (5). 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 represent the refractive index and extinction coefficient of the medium and are specific values.
The amplitude transmittance t can be uniquely obtained as the relationship of 1, k1.

Based on the above concept, for example, the wavelength 436
Assuming a g-line exposure of nm, the phase is 180 ± 10 °, the amplitude transmittance is 15 ± 5%, the refractive index n is changed, and the corresponding k is obtained, which is shown by a solid line and a broken line in FIG. Car
I can draw bu. In FIG. 5, the vertical axis represents the extinction coefficient k, the horizontal axis represents the refractive index n, and the broken line (a) is a curve showing the relationship between k and n when the amplitude transmittance is 10% and the phase is 170 degrees, and the broken line (b ) Is a curve showing the relationship between k and n when the amplitude transmittance is 20% and the phase is 190 degrees, and the broken line (c) is the amplitude transmittance 15% and the phase 180.
It is a curve which shows k and n relation at the time of degree. The region between the broken lines (a) and (b) is the allowable range at this time, and if the point defined by the refractive index n and the extinction coefficient k of a substance is within the range sandwiched by the broken lines, the substance is The layer film will have the function of a halftone phase shift film.

In the case of g-line, a film satisfying this condition is shown in FIG.
Amorphous Si indicated by points in 2 is present. However, when i-line exposure with a wavelength of 365 nm is considered, as shown in FIG. 13, amorphous Si (point of 0% N 2 gas) takes a value outside the allowable range. Therefore, it can be seen 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 is used.}
The same examination for ₄ (N ₂ gas 80% point) is also outside the allowable range. However, it can be seen that when two points of amorphous Si and Si ₃ N ₄ are connected by an arbitrary curve, the region sandwiched between the broken lines is always obtained. That is, if there is a substance having intermediate physical properties between amorphous Si and Si ₃ N ₄ , it falls within the allowable range. Reactive sputtering using Si and N ₂ is effective for forming this film. At this time, a film having arbitrary physical properties can be obtained by changing the reaction ratio of N ₂ . The physical properties at this time are indicated by black circles. A curve passing through a black circle passes through a region between broken lines, and the optimum conditions obtained here are n = 3.30 and k = 1.1 when the flow rate of nitrogen gas during sputtering is 15%.
9, the amplitude transmittance ratio is 0.142 and the phase difference is 180 degrees by setting the film thickness to S3.5 nm. By thus forming the Si ₃ N ₄ film having a different reaction ratio, a desired single-layer halftone phase shift film can be formed.

Considering exposure with a KrF excimer laser having a wavelength of 248 nm, as in the case of i-line exposure, as shown in FIG. 14, amorphous Si and Si _{3 are used.}
It was found that the physical property values of N ₄ are outside the allowable range, but substances having intermediate physical properties are within the allowable range.

It should be noted that the boundary condition can be set by fixing the phase to 180 degrees with a margin in the amplitude transmittance, or by fixing the amplitude transmittance with a margin in the phase. is there. Also, the allowable values may be changed in consideration of the effects and effects on the resist process and the like.

As a result of intensive studies conducted by us as a material satisfying the above conditions, silicon, a mixture containing silicon,
A substance formed of a mixture containing silicon, germanium, a compound containing germanium, a mixture containing germanium or a mixture of two or more thereof, or Cr,
Al, Ti, Sn, In, Co or other metal elements, metal compounds and materials formed of any one or a mixture of two or more of oxides, nitrides, hydrides, carbides and halides thereof. Was found to satisfy the above two conditions. Particularly, it can be said that silicon is a very effective semitransparent film in the g-line region and SiN in the i-line and KrF regions. The properties of these materials are shown in Table 1.

[0050] By injecting ions such as As, P, and B into the semitransparent film, the quality of the formed film can be slightly adjusted, for example, the optical constant can be adjusted.

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

Up to now, the basic concept for producing a single semitransparent film has been described, but when an attempt is made to produce a single semitransparent film, 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 prepared by adjusting the composition ratio of silicon and nitrogen, the silicon and nitrogen when the phase difference and the transmittance satisfy the optimum refractive index n and extinction coefficient k. The composition ratio is silicon: nitrogen = 1: 0.60.
It must be a degree. This is because the ratio of nitrogen is smaller than the composition ratio (silicon: nitrogen = 1: 1.33) of the Si ₃ N ₄ film which is usually obtained by nitriding silicon, and it is necessary to finely adjust the nitrogen flow rate.

When fine adjustment is required as described above, two or more kinds of semitransparent films having different composition ratios, for example, Si (silicon: nitrogen = 1: 1) are prepared, rather than forming a single layer semitransparent film.
0) and Si ₃ N ₄ (silicon: nitrogen = 1: 1.33) are preferable. At this time, Si
When the sputter amount of Si ₃ N ₄ molecules is calculated with respect to the sputter amount of 1 molecule, 0.042 is obtained, and if the sputter is performed twice under these conditions, a desired semitransparent phase shift film equivalent to the case of the multilayer is obtained. Is obtained. Further, when the semitransparent film for KrF is separated into the Si ₃ N ₄ film similarly to the i-line, silicon:
Nitrogen = 1: 0.9 is necessary, and for that purpose S
By setting the sputter amount of Si ₃ N ₄ molecules to 0.74 with respect to the sputter amount of 1 i molecule, a desired semitransparent film phase shift is obtained by two kinds of semitransparent films composed of Si and Si ₃ N ₄ films. be able to.

In these films, Si is considered to be a common element, silicon is used as the target, and after sputtering this, the silicon is sputtered while flowing nitrogen to produce Si ₃ N _4. The film is being deposited. In this sputter process, the target is fixed to one type,
Since the same apparatus can be used and only the common element Si needs to be processed at the time of processing, it is possible to perform the processing 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 , steps can be omitted in each of film formation and processing.

As a material for forming the semitransparent film, S is used.
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. FIG. 15 shows Cr—CrO ₂ , FIG. 16 shows Al—Al ₂ O ₃ , FIG. 17 shows Ti—TiO, and FIG. 18 shows GaAs—GaAsO.
Also, in these figures, the upper figure shows the i-line (wavelength 365n
m), the lower figure shows the case of the KrF line (wavelength 248 nm). In these figures, each material composition may be determined so as to fall within the region (allowable range) between the upper broken line and the lower broken line. The composition obtained here is applicable not only in the case of the present invention but also in the case of forming a single-layer semitransparent film by controlling the composition ratio according to the reaction conditions.

Here, for example, Ti-T under the KrF exposure condition is used.
As seen in the iO transition, it is possible that the halftone phase shift film according to the present invention cannot be formed if the allowable range is not crossed. In addition, i-line exposure condition of Cr-
When the end point substance is present 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 it is possible to consider 90 degrees as an acceptable range, the end-point substance can be used as it is.

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

First, as shown in FIG. 1A, a silicon film 11 having a film thickness of 71 nm is formed on a silicon oxide substrate 10 by a sputtering method. The Si ₃ N ₄ film 12 having a thickness of 19 nm was formed while continuously introducing nitrogen gas. At this time, the semitransparent phase shift film consisting of two layers 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 depositing an electron beam resist 13 to a film thickness of 0.5 μm, a conductive film 14 is further formed to a thickness of about 0.2 μm.

Then, as shown in FIG. 1C, a pattern of the resist 13 is formed by drawing on the conductive film 14 with an electron beam at 3 μC / cm ² and further developing. Here, the conductive film 14 is formed in order to prevent the charge-up of the electron beam when the resist 13 is insulative.

Then, as shown in FIG. 1 (d), the Si ₃ N ₄ film 12 exposed from the resist pattern and the Si ₃ N ₄ film 12 exposed from the resist pattern 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. Finally, by removing the resist pattern, as shown in FIG. 1 (e), the Si ₃ N ₄ film 1 is formed.
A phase shifter composed of 2 and the silicon film 11 can be obtained.

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

Through the exposure mask thus formed, a substrate called PFR7750 (manufactured by Japan Synthetic Rubber Co., Ltd.) was coated with a resist of 1.54 μm.
/ 5 reduction exposure (NA = 0.54, σ = 0.5) was performed to form a pattern. The exposure dose at this time is 300 mJ /
It was cm ² . The resolution of 0.7 μm could be resolved by using the mask of this embodiment, which was previously resolved by focusing on 0 μm with a 0.45 μm pattern.

Regarding the contact hole pattern, the pattern of 0.50 μm which could not be resolved by the conventional exposure is the pattern.
It was confirmed that the resolution was 1.5 μm with caspase.
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.

Second Embodiment Next, a second embodiment will be described.

This exposure mask is composed of silicon and Si ₃ formed by a sputtering method as a semi-transparent film pattern.
The feature is that a pattern made of N ₄ film is used.
It is used as a mask for F. here,
74 nm thick silicon film 1 on silicon oxide substrate 10
Create 1. While introducing nitrogen gas, Si ₃
The N ₄ film 12 was formed to 70 nm. At this time, the semi-transparent phase shift film consisting of two layers had a phase difference of 180 degrees with respect to the silicon oxide substrate 10 and an amplitude transmittance of 21.5%.

Then, after depositing the electron beam resist 13 to a film 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. A resist pattern is formed by drawing on the conductive film with an electron beam at 6 μC / cm ² and further developing.

CF using this resist pattern as a mask
_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 ₄ and O ₂ . Finally, the resist pattern is removed to remove the Si ₃ N ₄ film 12 and the silicon film 1.
A phase shifter composed of 1 can be obtained.

Through the exposure mask thus formed, a KrF resist called XP8843 (manufactured by Shipley Co.) was applied to a substrate having a thickness of 1.0 μm,
1/5 reduction exposure with excimer laser (NA = 0.4, σ =
0.5) was carried out to form a pattern. The exposure dose at this time was 40 mJ / cm ² . The resolution of 0.7 μm can be resolved by using the mask of this embodiment, which was previously resolved with a focus of 0.3 μm pattern and focus margin = 0 μm. Regarding the contact hole pattern, it was confirmed that the 0.30 μm pattern, which was not resolved by conventional exposure, was resolved by focus margin-1.2 μm.

In this example, the formation of the silicon nitride film as the phase shifter was carried out by sputtering using silicon as the target while controlling the amount of nitrogen gas. However, a mosaic target of silicon and silicon nitride was used. A sputter link 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, the surface may be modified by performing ion implantation or heat treatment in order to finely adjust the refractive index and the amplitude transmittance.

Third Embodiment Next, a third embodiment will be described.

This example relates to an i-line exposure mask formed using Cr and CrO ₂ . When Cr is formed as a single-layer semi-transparent film by reactive sputtering, the flow rate of oxygen gas is adjusted so that 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 to be formed by a two-layer film of Cr and CrO ₂ , the molecular composition ratio of each is set to Cr: CrO ₂ = 1: 0.567, so that it is superior to the silicon oxide substrate. A phase difference of 180 degrees and an amplitude transmittance of 18% can be obtained.

First, as shown in FIG. 2A, a Cr film 21 having a film thickness of 70 nm is formed on the silicon oxide substrate 10 by the sputtering method. Then, while introducing oxygen gas, a CrO ₂ film 22 having a thickness of 42 nm was formed.

Then, similarly to the first embodiment, an electron beam resist is formed with a film thickness of 1.0 μm, and the electron beam resist is irradiated with 6 μC.
Draw / cm ² and develop to make a resist pattern.

With this resist pattern as a mask, Cl
Cr film 21 and C exposed from the resist pattern by reactive ion etching with a mixed gas of ₂ and O _2.
The rO ₂ film 22 is sequentially removed. Finally, by removing the resist pattern, a phase shifter composed of the Cr film 21 and the CrO ₂ film 22 as shown in FIG. 2B can be obtained.

In this embodiment, when the desired amplitude transmittance is about 26%, the CrO ₂ film is used as a single layer film and the film thickness is controlled to 130 nm to obtain a phase shifter composed of only the CrO ₂ film. You can also

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

Also regarding 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, it is possible to obtain a better processed shape by transferring the pattern using this mask and processing the substrate using the formed resist pattern as a mask.

In this embodiment, the shifter film made of CrO _x may be formed by CVD or the like in which the composition ratio of the atmospheric gas is controlled. Further, in this embodiment, Cr and CrO are used.
_{The second} etching may be chemical etching (CDE) or wet etching (using a ceric ammonium nitrate solution).

Fourth Embodiment Next, a fourth embodiment will be described.

This example relates to an i-ray exposure mask formed by using Al and Al ₂ O ₃ . When Al is formed as a single-layer translucent film by reactive sputtering, the desired translucency can be obtained by adjusting the flow rate of oxygen gas so that the composition ratio of oxygen element to 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 that it is formed of a layer film, by setting the molecular composition ratio of each of them to Al: Al ₂ O ₃ = 1: 18.3, a phase difference of 180 ° and an amplitude transmittance of 15% with respect to a silicon oxide substrate can be obtained. You can

First, as shown in FIG. 3A, an Al film 31 having a thickness of 23 nm is formed on the silicon oxide substrate 10 by the sputtering method. Subsequently, while introducing oxygen gas, an Al ₂ O ₃ film 32 having a thickness of 248 nm was formed.

Then, similarly to the first embodiment, an electron beam resist is formed with a film thickness of 1.0 μm, and the electron beam is applied at 6 μC /
Draw with cm ² , and further develop to make a resist pattern.

Cl using this resist pattern as a mask
Al and Al ₂ O exposed from the resist pattern by reactive ion etching with a mixed gas of ₂ and O _2.
3 Remove the film sequentially. Finally, by removing the resist pattern, the Al film 3 as shown in FIG.
A phase shifter composed of 1 and the Al ₂ O ₃ film 32 can be obtained.

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

Regarding the line & space pattern, the one which was resolved with the focus exposure of 0.3 μm and the focus exposure of 0 μm in the conventional exposure is the focus exposure with the mask of this embodiment. It became possible to resolve at 0.9 μm. Regarding the contact hole pattern,
It was confirmed that the 0.40 μm pattern, which was not resolved by conventional exposure, is resolved by the focus margin of 1.5 μm. In addition, by transferring using this mask and using the formed resist pattern as a mask to process the substrate,
It is possible to obtain a better processed shape.

Fifth Embodiment Next, a fifth embodiment will be described.

This example relates to a KrF exposure mask prepared by using Al and Al ₂ O ₃ . When forming a single layer of semitransparent Al by reactive sputtering, the desired semitransparent phase can be obtained by adjusting the flow rate of the oxygen gas so that the composition ratio of the oxygen element to the 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 Al:
By setting Al ₂ O ₃ = 1: 10, a phase difference of 180 ° and an amplitude transmittance of 15% can be obtained with respect to the silicon oxide substrate.

First, an Al film 31 having a film thickness of 14 nm is formed on the silicon oxide substrate 10 by the sputtering method.
While continuing to introduce oxygen gas, the Al ₂ O ₃ film 32 is deposited to 1
61 nm was created. Then, an electron beam resist is formed to a film thickness of 1.
0 μm, and draw with electron beam at 6 μC / cm ² ,
Further development is carried out to obtain a resist pattern.

With this resist pattern as a mask, Cl
Al film 31 and Al exposed from the resist pattern by reactive ion etching with a mixed gas of ₂ and O _{2.
The 2} O ₃ film 32 is sequentially removed. Finally, the resist pattern is removed to obtain a phase shifter including the Al film 31 and the Al ₂ O ₃ film 32.

Through the exposure mask thus formed, a KrF resist called XP8843 (manufactured by Shipley Co., Ltd.) was applied to a substrate having a thickness of 1.0 μm,
Excimer laser 1/5 reduction exposure (NA = 0.4, σ =
0.5) was carried out to form a pattern. The exposure dose at this time was 40 mJ / cm ² . And the conventional 0.30
By using the mask of this embodiment, it was possible to resolve the image having a focus pattern of 0.7 μm by using the mask of the present example, while the image having the pattern of μm pattern and the resolution of 0 μm was resolved.

As for the contact hole pattern, a 0.30 μm pattern not resolved by conventional exposure.
It was confirmed that the image resolved at the focus margin = 1.2 μm.

Sixth Embodiment Next, a sixth embodiment will be described.

This example relates to an i-ray exposure mask made using Ti and TiO ₂ . When Ti is formed as a single layer semi-transparent film by reactive sputtering, the desired semi-transparency can be obtained by adjusting the flow rate of oxygen gas so that 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 by a two-layer film of Ti and TiO ₂ , the molecular composition ratio of each is Ti: T.
When 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 thickness of 196 nm is formed on the silicon oxide substrate 10 by the sputtering method.
A Ti film 41 is formed. Subsequently, while introducing oxygen gas, a TiO ₂ film 42 having a thickness of 84 nm was formed.

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

Finally, by removing the resist pattern, Ti film 41 and Ti film as shown in FIG. 4 (b) are formed.
A phase shift composed of the O ₂ film 42 can be obtained.

A substrate coated with a resist for i-line (PFRIX500 (manufactured by Japan Synthetic Rubber Co., Ltd.)) to a thickness of 1.3 μm was passed through the mask for projection exposure prepared in this example, and the i-line of a mercury lamp was used. / 5 reduction exposure (NA = 0.5, σ
= 0.6) was performed to form a pattern. The exposure amount required at this time was 300 mJ / cm ² .

Regarding the line & space pattern, although the resolution was 0.35 μm in the conventional exposure with a focus margin of 0 μm, the focus and mask with the mask of this embodiment was used. It became possible to resolve at gin = 0.9 μm. As for the contact hole pattern, 0.40 μm pattern not resolved by conventional exposure.
It was confirmed that the image resolved at 1.5 μm of focus margin. Further, it is possible to obtain a better processed shape by transferring the pattern using this mask and processing the substrate using the formed resist pattern as a mask.

The present invention is not limited to the above embodiments. For example, in each embodiment, the materials of the first semitransparent film and the second semitransparent film may be exchanged. Further, although two kinds of semitransparent films are used in the embodiment, three or more kinds of semitransparent films may be used. Furthermore, the same semi-transparent film (two or more types) may be laminated multiple times. In addition, within the scope of the present invention,
Various modifications can be implemented.

Embodiment 7 FIG. 5 is a sectional view showing a manufacturing process of an exposure mask substrate of a seventh embodiment of the present invention. This exposure mask substrate is
A substrate for producing a phase shift mask for g-line,
An amorphous silicon film 61 is formed as a semi-transparent film on the transparent substrate 60 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 of the amorphous silicon film 62 by using silicon as a target.
3 is formed.

That is, first, as shown in FIG. 5A, an amorphous silicon film 61 having a film thickness of 59 nm is formed on a quartz substrate 60 having a thickness of 2.5 mm by a sputtering method. The amorphous silicon film 61 has a refractive index n = 4.
At 93, the amplitude transmittance with respect to the quartz substrate was 17.4%.

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

Further, as shown in FIG. 5 (c), a second layer is formed by sputtering using a silicon target.
59 nm of the amorphous silicon film 63 was deposited. The amplitude transmittance of the thus obtained two-layer film including the silicon oxide film was 3.0%. A substrate for an exposure mask is obtained in this way, but the thickness of the amorphous silicon film as the second semi-transparent film has an amplitude transmittance of 5.0% or less including the first amorphous silicon film and the silicon oxide film. Any value that is

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

First, as shown in FIG. 6 (a), as shown in FIG.
An electron beam resist 64 having a film thickness of 500 nm is formed on the surface of the exposure mask substrate obtained in the step shown in FIG. 5C, and a coatable conductive film 65 is further formed so as to have a film thickness of 200 nm.

Next, as shown in FIG. 6 (b), drawing is performed by an electron beam with data including the device pattern and the area outside the device pattern, and the resist pattern 64a is developed.
To form. Here, again, the resist pattern 64a is formed by drawing with an electron beam on the coatable conductive film 65 and further developing. Here, the coatable conductive film 65 is formed by the electron beam char when the resist 64 is insulative.
This is to prevent jiup. B in the figure indicates the boundary between the pattern area and the non-pattern area.

Next, as shown in FIG. 6C, the second resist exposed from the resist pattern is subjected to reactive ion etching with CF ₄ gas using the resist pattern as a mask.
After the amorphous silicon film 63 is removed by etching in, by reactive ion etching using a mixed gas of CF ₄ and O ₂ switches the gas, first in the CF ₄ switch the further gas etched the silicon oxide film 62 1
The amorphous silicon film 61 was removed by etching.

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

Thus, as shown in FIG. 6 (e), the first
After forming a phase shift pattern of a two-layer structure consisting of the amorphous silicon and the second amorphous silicon, an electron beam resist 66 is formed with a film thickness of 500 nm, and a coating conductive film 67 is formed with a film thickness of 200 nm. To do.

Next, as shown in FIG. 6 (f), drawing is performed by the electron beam using the data created so that the resist film remains in the region outside the device pattern, and development is performed to form a resist pattern 66a. Also here, the resist pattern 66a is formed by drawing with an electron beam on the coatable conductive film 67 and further developing.

Next, as shown in FIG. 6 (g), the resist pattern is used as a mask to carry out reactive ion etching with CF ₄ gas, and the silicon oxide film 62 is used as an etching stopper to form a second amorphous film in the pattern region. The silicon film 63 is removed by etching, and the silicon oxide film 62 is removed by etching.

Finally, as shown in FIG. 6 (h), this resist pattern was removed.

The exposure mask thus formed is a semitransparent film having an amplitude transmittance of 17.4%, which is made of only the first amorphous silicon film in the device pattern region.
Outside the device pattern area, 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 the transfer, the thinning of the pattern and the lack of the depth of focus can occur even when the exposure is performed a plurality of times. Can be prevented.

Embodiment 8 Although the exposure mask for g-line is explained in the above-mentioned embodiment, the exposure mask for i-line will be explained here.

As in Example 6 shown in FIGS. 5 (a) to 5 (c), silicon was used as a target on a quartz substrate having a thickness of 2.5 mm and a film thickness of 80 was obtained by sputtering in a nitrogen atmosphere.
nm first silicon nitride film SiN _β (0.6 ≤ β ≤ 0.8
) Is created. The refractive index of this silicon nitride film is n =
At 3.40, the amplitude transmittance with respect to the quartz substrate was 15.1%.

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

Further, a second silicon nitride film SiN _β (0.6 ≦ β ≦ 0.8) having a film thickness of 80 nm is formed on this by a sputtering method using silicon as a target. The amplitude transmittance of the thus obtained two-layer film including the silicon oxide film was 2.2%. Note that a silicon film may be used instead of the second silicon nitride film.
The film 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, in the same manner as shown in FIGS. 6 (a) to 6 (h), an electron beam resist having a film thickness of 500 nm is formed on the exposure mask substrate obtained in the above step, and the coating conductive film is formed. The film 65 is formed to have a film thickness of 200 nm.

Next, an electron beam is used to draw a device pattern and data including the area outside the device pattern, and development is performed to form a resist pattern. In this case as well, drawing is performed with an electron beam on the coatable conductive film, and further development is performed to form a resist pattern.

Then, the second silicon nitride film exposed from the resist pattern is removed by reactive ion etching with a mixed gas of CF ₄ + O ₂ + N ₂ using the resist pattern as a mask, and then the gas is changed to CF ₄ The silicon oxide film is etched by reactive ion etching using a mixed gas of C and O _2, and the gas is further changed to a mixed gas of CF ₄ + O ₂ + N ₂ to remove the first silicon nitride film by etching, and a resist pattern is formed. To remove.

After forming the two-layered phase shift pattern made of the first and second silicon nitrides in this manner, an electron beam resist is formed to a film thickness of 500 nm, and a coatable conductive film is formed to a film thickness of 200 nm. To be formed.

Next, an electron beam is used to draw with the data created so that the resist film remains in the area outside the device pattern, and development is performed to form a resist pattern.

Further, by using this resist pattern as a mask, reactive ion etching with a mixed gas of CF ₄ + O ₂ + N ₂ is performed to remove the second silicon nitride film in the pattern region by etching using the silicon oxide film as an etching stopper. Then, the silicon oxide film is removed by etching.

Finally, this resist pattern was removed.

The exposure mask thus formed is a semi-transparent film having an amplitude transmittance of 15.1% made of only the first silicon nitride film in the device pattern area, and an amplitude transmittance of 2. 1% outside the device pattern area. It is a 2% light-shielding film.

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

Embodiment 9 FIG. 7 is a cross-sectional view showing the steps of manufacturing an exposure mask substrate according to the ninth embodiment of the present invention. This exposure mask substrate is
A substrate for making a phase shift mask for i-line,
On the transparent substrate 70, a Cr film 71 is formed as a semi-transparent film by a sputtering method, a coating glass layer 72 is formed on the upper layer, and a Cr film 73 is further formed on the upper layer by a sputtering method using Cr as a target. is there.

That is, first, as shown in FIG. 7A, 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. This first
The Cr film 71 had a refractive index of n = 1.98 and an amplitude transmittance of 20.2% with respect to the quartz substrate.

Subsequently, as shown in FIG. 7B, a coating glass 72 having a film thickness of 329 nm is formed on the Cr film 71.
At this time, the phase difference was set to 180 degrees in consideration of the phase difference between the Cr film and the coated glass.

Furthermore, as shown in FIG. 7 (c), C
The second C is formed by the sputtering method using r as a target.
An r film 73 was deposited to a thickness of 35 nm. The amplitude transmittance of the thus obtained two-layer film including the coated glass film was 4.0%.

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

First, as shown in FIG. 8A, as shown in FIG.
An electron beam resist 74 having a film thickness of 500 nm is formed on the surface of the exposure mask substrate obtained in the step shown in FIG.

Next, as shown in FIG. 8 (b), drawing is performed by the electron beam using the data including the device pattern and the area outside the device pattern, and the resist pattern 74a is developed.
To form. Here, B in the figure indicates the boundary between the pattern area and the non-pattern area.

Next, as shown in FIG. 8C, the second Cr film 73 exposed from the resist pattern is removed by reactive ion etching with 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 change the first Cr film 71.
Was removed by etching. Then, as shown in FIG. 8D, the resist pattern is removed.

Thus, as shown in FIG. 8 (e), the first
After forming the phase shift pattern 75 having a two-layer structure composed of Cr and the second Cr, an electron beam resist 76 and a conductive film 77 are formed with a film thickness of 500 nm.

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

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

Finally, as shown in FIG. 8 (h), this resist pattern was removed.

The exposure mask thus formed is a semi-transparent film having an amplitude transmittance of 20.2% consisting of only the first Cr film in the device pattern region, and an amplitude transmittance of 4% outside the device pattern region. 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, thinning of the pattern and lack of the depth of focus can occur 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 exposure mask substrate is capable of forming a light shielding film outside the pattern region. FIG. 9 is a cross-sectional view showing the manufacturing process of the exposure mask substrate of the tenth embodiment of the present invention. This exposure mask substrate is a substrate for forming a phase shift mask for i-line, and a silicon nitride film SiN _0.681 is formed on the transparent substrate 80 as a semi-transparent film to serve as a phase shifter, and a light-shielding layer is formed on the upper layer. A Cr film 82 is formed as a film, and the upper layer is covered with a CrO film 83 as an antireflection layer.

That is, first, as shown in FIG. 9 (a), 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 nitrogen is added to 1 mol of Si. A uniform silicon nitride film SiN _0.6 of _0.6 mol is deposited to a film thickness of 75 nm. Here, the silicon nitride film SiN _0.6 is i of the mercury lamp.
The phase of light in the film is 254 degrees with respect to the line, and it is 75 nm.
The phase is designed to be delayed by 180 degrees with respect to the phase of light traveling in the air of 74 degrees. I of this SiN _0.6 film 81
The amplitude transmittance for the line was 3%.

Subsequently, as shown in FIG. 9B, a film thickness of 75 is formed as a light-shielding film on the upper layer of the silicon nitride film SiN _0.681.
A Cr film 82 of nm is formed by the sputtering method.

Further, as shown in FIG. 9C, a CrO film 83 having a thickness of 30 nm was deposited as an antireflection layer on this by a sputtering method using Cr as a target in an oxygen atmosphere.

Next, using this exposure mask substrate, an exposure mask is formed 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. Also in this example, the exposure mask substrate is capable of forming a light-shielding film outside the pattern region. This exposure mask substrate is a substrate for making a phase shift mask for a KrF excimer laser, and a silicon nitride film SiN _0.9 is formed as a semitransparent film to be a phase shifter on a silicon oxide substrate having a thickness of 2.5 mm. Then, a Cr film is formed as a light-shielding film on this upper layer, and the upper layer is covered with a CrO film as an antireflection layer.

That is, first, reactive sputtering was performed on a silicon oxide substrate having a thickness of 2.5 mm in a nitrogen atmosphere with a silicon target, and a uniform silicon nitride film SiN _0.9 containing 0.9 mol of nitrogen per 1 mol of Si. The film thickness 8
It is deposited to have a thickness of 0 nm. Here, the silicon nitride film S
iN _0.9 has a phase of 296 degrees with respect to the light of 248 nm of a KrF excimer laser in the film, and is designed to be delayed by 180 degrees with respect to the phase of 116 degrees of light traveling in the air of 80 nm. The amplitude transmittance of this SiN _0.9 film with respect to the light of 248 nm of the KrF excimer laser was 4%.

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

Further, on top of this, C in an oxygen atmosphere
A CrO film having a thickness of 30 nm was deposited as an antireflection layer by a sputtering method using r as a target.

Here, the same result can be obtained even if the structure is the same as that of the above-mentioned twelfth embodiment except that SnO which is a conductive film is interposed between SiN and Cr.

Twelfth Embodiment Next, another exposure mask substrate will be described as a twelfth embodiment of the present invention. Also in this example, the exposure mask substrate is capable of forming a light-shielding film outside the pattern region. This exposure mask substrate is a substrate for forming a phase shift mask for a KrF excimer laser, and a silicon nitride film SiN _1.8 is formed as a semitransparent film to be a phase shifter on a silicon oxide substrate having a thickness of 2.5 mm. Then, a Cr film is formed as a light-shielding film on this upper layer, and the upper layer is covered with a CrO film as an antireflection layer.

That is, first, reactive sputtering is performed on a silicon oxide substrate having a thickness of 2.5 mm in a nitrogen atmosphere with silicon as a target, and a uniform silicon nitride film SiO _1.8 containing 1.8 mol of oxygen with respect to 1 mol of Si is used. The film thickness 9
Deposit to a thickness of 4 nm. Here, the silicon nitride film S
The iO _1.8 is designed so that the phase of light in the film is 355 degrees with respect to the light of 248 nm of the KrF excimer laser, and the phase is delayed by 180 degrees with respect to the phase of 175 degrees of light traveling in the air of 94 nm. The amplitude transmittance of this SiO _1.8 film for the KrF excimer laser light of 248 nm was 4%.

Subsequently, a 70 nm thick Cr film is formed as a light-shielding film on the silicon nitride film SiO _1.8 by a sputtering method.

On top of this, further, in an oxygen atmosphere, C
A CrO film having a thickness of 30 nm was deposited as an antireflection layer by a sputtering method using r as a target.

Embodiment 13 Next, another exposure mask substrate will be described as a 13th embodiment of the present invention. Also in this example, the exposure mask substrate is capable of forming a light-shielding film 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.
A silicon nitride film SiN _0.6 is formed as a semi-transparent film serving as a phase shifter on a silicon oxide substrate having a thickness of 10 mm, SnO is deposited to a thickness of 10 nm as a conductive film on the upper layer, and then a Cr film is formed as a light-shielding film. C as an antireflection layer
It is characterized by being covered with an rO film.

That is, first, reactive sputtering was performed on a silicon oxide substrate 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 containing 1.8 mol of nitrogen per 1 mol of Si was formed. The film thickness 7
Deposit to a thickness of 5 nm. Here, the silicon nitride film S
iN _0.6 has a phase of light of 254 degrees in the film with respect to the i-line, and 18 for phase of 74 degrees of light traveling in the air of 75 nm.
It is designed to have a 0 degree phase delay. This SiN
_The amplitude transmittance of the _0.6 film for the i-line was 3%. Subsequently, SnO is deposited to a thickness of 10 nm as a conductive film on the silicon nitride film SiN _0.6 by sputtering, and then a Cr film having a thickness of 70 nm is formed as a light-shielding film by a sputtering method.

Then, on top of this, C in an oxygen atmosphere
A CrO film having a thickness of 30 nm was deposited as an antireflection layer by a sputtering method using r as a target.

The conductive film SnO is directly formed on the transparent substrate, and the silicon nitride film is formed on the transparent film, and the same result is obtained even if the structure is the same as that of the thirteenth embodiment.

Embodiment 14 Next, another exposure mask substrate will be described as a 14th embodiment of the present invention. Also in this example, the exposure mask substrate is capable of forming a light-shielding film outside the pattern region. This exposure mask substrate is a substrate for making a phase shift mask for light of 248 nm of a KrF excimer laser, and is a silicon nitride film as a semitransparent film which becomes a phase shifter on a silicon oxide substrate having a thickness of 2.5 mm. SiN _0.9 is formed to a film thickness of 80 nm, and Sn is formed as a conductive film on the upper layer.
After depositing O to a thickness of 10 nm, a Cr film is formed as a light-shielding film on the upper layer, and the upper layer is covered with a CrO film as an antireflection layer.

That is, first, reactive sputtering is performed on a silicon oxide substrate having a thickness of 2.5 mm in a nitrogen atmosphere with a silicon target, and a uniform silicon nitride film SiN _0.9 having 0.9 mol of nitrogen per 1 mol of Si is formed. The film thickness 8
It is deposited to have a thickness of 0 nm. Here, the silicon nitride film S
iN _0.9 has a phase of 296 degrees with respect to the light of 248 nm of a KrF excimer laser in the film, and is designed to be delayed by 180 degrees with respect to the phase of 116 degrees of light traveling in the air of 80 nm. The amplitude transmittance of this SiN _0.9 film with respect to the light of 248 nm of the KrF excimer laser was 4%.

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

Then, further on this, in an oxygen atmosphere, C
A CrO film having a thickness of 30 nm was deposited as an antireflection layer by a sputtering method using r as a target.

Fifteenth Embodiment Next, another exposure mask substrate will be described as a fifteenth embodiment of the present invention. Also in this example, the exposure mask substrate is capable of forming a light-shielding film 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.
SnO as a conductive film on a silicon oxide substrate of mm
After depositing 0 nm, a two-layer film of a silicon oxide film SiO ₂ and a silicon film is formed as a semi-transparent film to be a phase shifter, and then a Cr film is formed as a light-shielding film on the upper layer, and the upper layer is an antireflection layer. It is characterized by being coated with a CrO film.

That is, first, on a silicon oxide substrate having a thickness of 2.5 mm, SnO was deposited to a thickness of 10 nm by a sputtering method, and a silicon oxide film having a thickness of 150 nm was formed on the upper layer by a CVD method, and then a silicon film having a thickness of 37 nm was formed. Are formed by a sputtering method. Here, the light transmitted through the two-layer film has a phase of 364 degrees with respect to the i-line, and
The phase is designed to be delayed 180 degrees with respect to the phase 184 degrees of the light traveling in the air of 87 nm. The amplitude transmittance of the two-layer film for the i-line was 2.5%.

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

Then, on top of this, C in an oxygen atmosphere
A CrO film having a thickness of 30 nm was deposited as an antireflection layer by a sputtering method using r as a target.

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

Example 16 Next, using this exposure mask substrate, an exposure mask is formed in the same manner as in the above-described example. Here, the first embodiment
The exposure mask substrate 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 a silicon nitride film SiN _0.9 91 as a semitransparent film to be a phase shifter on a silicon oxide substrate 90 having a thickness of 2.5 mm. Is formed, a Cr film 92 is formed as a light-shielding film on the upper layer, and the upper layer is covered with a CrO film 93 as an antireflection layer.

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

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

Next, as shown in FIG. 10 (c), the resist pattern is used as a mask to carry out reactive ion etching with Cl ₂ gas to expose the C exposed from the resist pattern.
After removing the r film and the CrO film by etching, the gas is switched and the exposed silicon nitride film SiN is formed by reactive ion etching using a mixed gas of CF ₄ and O _2.
0.9 91 is removed by etching.

After this, as shown in FIG. 10D, the resist pattern is removed by a mixed solution of sulfuric acid and hydrogen peroxide solution. As a result, a phase shift pattern composed of the light-shielding film and the semi-transparent film is formed, but at the same time, the alignment mark M for performing exposure for removing the unnecessary light-shielding film is formed.
Is formed.

After the phase shift pattern consisting of the light-shielding film and the semitransparent film is formed in this manner as shown in FIG. 10 (e), an electron beam resist 96 is formed to a film thickness of 500 nm, and the coatable conductive film 97 is further formed. Is formed to have a film thickness of 200 nm.

Next, as shown in FIG. 10 (f), drawing is performed by electron beams at 4 μC / cm ² with data created so that the resist film remains in the device pattern outside region,
Development is performed to form a resist pattern 96a. even here,
A resist pattern 96a is formed by drawing on the coatable conductive film 97 with an electron beam and further developing.

Then, as shown in FIG. 10G, the CrO film 93 / Cr film 92 is removed by reactive ion etching with Cl ₂ gas using this resist pattern as a mask.

Finally, as shown in FIG. 10 (h), this resist pattern was removed with a mixed solution of sulfuric acid and hydrogen peroxide solution.

The exposure mask thus formed is a semi-transparent film consisting 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, thinning of the pattern and lack of the depth of focus can occur even when the exposure is performed a plurality of times. Can be prevented.

Embodiment 17 In the above-mentioned embodiment, the case where the exposure mask substrate having both the semitransparent film and the light shielding film as the phase shift layer is used is explained. Here, the Cr film 92 is used. And the exposure mask substrate on which the CrO film 93 is formed,
A method of forming the phase shift layer pattern after forming the light shielding film pattern outside the frame portion, that is, the pattern region will be described.

First, as shown in FIG. 11A, the thickness 2.
Cr film 92 and CrO film 9 on 5 mm silicon oxide substrate 90
The electron beam resist 94 is formed on the substrate for the exposure mask on which 3 is formed.
Is formed to have a film thickness of 500 nm, and further, the coating conductive film 95 is formed to have a film thickness of 200 nm.

Next, as shown in FIG. 11 (b), drawing is performed by an electron beam with data for forming the alignment mark M and the light-shielding film in the area outside the device pattern, and development is performed to form a resist pattern. In this case as well, a resist pattern is formed by drawing on the coatable conductive film with an electron beam and further developing.

Next, as shown in FIG. 11 (c), the resist pattern is used as a mask to carry out reactive ion etching with Cl ₂ gas to expose the C exposed from the resist pattern.
The rO / Cr film is removed by etching, and the resist pattern is removed.

After the alignment mark M and the light-shielding film outside the device pattern are formed in this way,
As shown in FIG. 1 (d), reactive sputtering was performed in a nitrogen atmosphere targeting silicon to obtain a uniform silicon nitride film SiN _{0.6 with} 0.6 mol of nitrogen per 1 mol of Si.
Is deposited to have a film thickness of 75 nm. Here, the silicon nitride film SiN _0.6 has a phase of light of 254 degrees in the film with respect to the i-line of a mercury lamp, and is designed to be delayed by 180 degrees with respect to the phase of 74 degrees of light traveling in the air of 75 nm. ing. The amplitude transmittance of the SiN _0.6 film 91 for the i-line was 3%.

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

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

Further, as shown in FIG. 11 (g), the SiN _0.6 film 9 is formed by reactive ion etching with a mixed gas of CF ₄ + O ₂ using this resist pattern as a mask.
Etch 1.

Finally, as shown in FIG. 11 (h), this resist pattern was removed.

The exposure mask thus formed is a semi-transparent 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 sixteenth embodiment.

Also in this case, since the exposure light is shielded at least in the area outside the pattern area where the light reaches the wafer by the transfer, even when the exposure is performed a plurality of times, the pattern thinning and the focus are reduced. It is possible to prevent insufficient depth.

The present invention is not limited to the above embodiments. Further, although two kinds of semitransparent films are used in the embodiment, three or more kinds of semitransparent films may be used. Furthermore, the same semi-transparent film (two or more types) may be laminated multiple times. In addition, various modifications can be made without departing from the scope of the present invention.

[0198]

As described above, according to the present invention,
Regarding a pattern composed of a plurality of semitransparent 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 to realize an exposure mask that can be used.

Further, according to the present invention, the transmittance is set to 5% or less outside the pattern area in order to prevent the light transmitted to the outside of the pattern area due to the light transmitted through the semitransparent film. It is possible to prevent the occurrence of pattern thinning and form a highly reliable pattern.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing the manufacturing process of the exposure mask of the third embodiment,

FIG. 3 is a cross-sectional view showing the manufacturing process of the exposure mask of the fourth embodiment,

FIG. 4 is a cross-sectional view showing the manufacturing process of the exposure mask of the sixth embodiment,

FIG. 5 is a cross-sectional view showing the manufacturing process of the exposure mask substrate of the seventh embodiment,

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

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

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

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

FIG. 10 is a cross-sectional view showing the manufacturing process of the exposure mask of the sixteenth embodiment,

FIG. 11 is a cross-sectional view showing the 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 semi-transparent film pattern single-layer film and an actual measured value 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 an actual measurement value 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 an actually measured value 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 the relationship between the refractive index and the extinction coefficient of Al—Al ₂ O ₃ .

FIG. 17 is a characteristic diagram showing the relationship between the refractive index and the extinction coefficient of Ti—TiO,

FIG. 18 is a characteristic diagram showing the relationship between the refractive index and the 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 diagram showing a pattern outside a pattern region and an exposure state when exposure is performed using the conventional halftone phase shift film.

FIG. 21 is a diagram showing a state of a pattern area after exposure when the exposure is performed using the 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 Coating glass layer 73 Cr film 74 Electron beam resist

Claims (6)

[Claims] 1. An exposure mask in which a mask pattern is formed on a transparent substrate, wherein the mask pattern has an optical path length for exposure light which is different from a transparent portion of the transparent substrate by a predetermined amount. This semi-transparent film pattern includes the constructed semi-transparent film pattern.
Is an exposure mask characterized by being formed by laminating layers having different compositions containing the same element. 2. A method of manufacturing an exposure mask, wherein a mask pattern is formed on a translucent substrate, the mask pattern including a semitransparent film having an optical path length different from that of the transparent portion by a predetermined amount. A method of manufacturing an exposure mask, comprising sequentially laminating layers having different compositions containing the same element as a semitransparent film. 3. A transparent substrate on which a phase difference from the transparent portion of the transparent substrate is adjusted within a range of 180 ± 10 degrees and an amplitude transmittance of 10 to 40%. Translucent layer of layers or a translucent pattern consisting of at least one translucent layer and a multi-layered first translucent film of a transparent layer, and further laminated in a partial region of the translucent pattern, 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 semi-transparent film having an amplitude transmittance of 10 to 40%. 4. The exposure mask according to claim 3, wherein the part of the region includes at least an outer peripheral region of a region that contributes as a semiconductor element when transferred onto the wafer. 5. A transparent substrate on which a phase difference from the transparent portion of the transparent substrate is adjusted within a range of 180 ± 10 degrees and an amplitude transmittance of 10 to 40%. A first semi-transparent film consisting of at least one semi-transparent layer or at least one semi-transparent layer and a transparent layer, and the whole or part of the first semi-transparent film further laminated, and the amplitude transmittance of the region Between the light-shielding layer or the second semi-transparent film having an amplitude transmittance of 10 to 40%, which is adjusted to be 5% or less, and the first semi-transparent film and the second semi-transparent film. A substrate for an exposure mask, comprising an oxide film, a nitride film, a hydroxide film, a carbide film, or a halogenated film which has been formed. 6. A single unit adjusted on a transparent substrate so that a phase difference with a transparent portion of the transparent substrate is different in a range of 180 ± 10 degrees and an amplitude transmittance is 10 to 40%. A first semitransparent film forming step of forming a first semitransparent film composed of a semitransparent layer of at least one layer or at least one semitransparent layer and a transparent layer, and a third semitransparent film on the first semitransparent film. A third film forming step of forming a film, and a light-shielding layer adjusted to have an overall amplitude transmittance of 5% or less or a second semi-transparent film having an amplitude transmittance of 10 to 40% on the upper layer. And a second translucent film forming step of forming a film, and an etching step of selectively removing the second semitransparent film by using the third film as an etching stopper. Method.