JPH0851055A - Manufacture of x-ray exposing mask - Google Patents

Abstract

PURPOSE:To obtain an X-ray exposing mask having high quality mask shape and little mask distortion by a method wherein an X-ray transmitting pattern is formed, and after an X-ray absorber has been deposited on the whole surface of a substrate, the X-ray absorber is removed until an X-ray transmitting film is exposed, and the X-ray absorber is left on the pattern part only formed on the X-ray transmitting film. CONSTITUTION:A resist film 4 is formed on the silicon dioxide film 3 on the membrane film 2 on the surface side of a silicon substrate 1, a pattern is drawn, and an L and S pattern 6 is formed by conducting an anisotropic dry etching method using an L and S pattern 5 as an etching mask. Subsequently, a Ti layer 11 and a TiN layer 12 are sucessively formed on the whole surface of the silicon substrate 1, and a W-layer 13 is deposited as an X-ray absorber layer. Then, the W-layer 13 is flattened until the surface of the silicon dioxide film 3 appears using a chemical-mechanical polishing method, and the X-ray absorber L & S pattern 14 of the W-layer is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an X-ray exposure mask having a structure in which a patterned X-ray absorber layer is formed on an X-ray transparent film.

[0002]

2. Description of the Related Art An X-ray mask generally used for X-ray exposure is manufactured by forming an X-ray absorber pattern consisting of an X-ray absorber layer that absorbs X-rays on a membrane film that transmits X-rays well. Has been done.

An example of a method for manufacturing an X-ray exposure mask using a conventional dry etching technique will be briefly described. First, on both sides of a silicon (Si) substrate, silicon nitride (Si
N) the membrane film is formed to a thickness of about 2 μm by the low pressure CVD method, and then the tantalum (Ta) X-ray absorber layer is formed to a thickness of about 0.65 μm by the sputtering method.
Subsequently, a silicon dioxide (SiO ₂ ) layer is formed to a thickness of about 0.2 μm by the ECR method.

Next, an EB (electron beam) resist is coated on this silicon substrate, a pattern is drawn by an EB exposure device, and the resist pattern described above is converted into a SiO ₂ pattern by an anisotropic dry etching (RIE) method. RIE using this SiO ₂ pattern as an etching mask
A Ta absorber pattern is formed by the method. Finally, wet etching is performed from the back side of the silicon substrate using the SiN film as an etching mask to form a membrane window on the silicon substrate, and the process is completed. This last step is called a back etching step. There are cases where this back etching is performed prior to the patterning and cases where it is performed last.

Conventionally, in the method of manufacturing an X-ray exposure mask by the dry etching technique described above, a rectangular X-ray absorber pattern is formed in the vertical direction which coincides with the design pattern in plan view. Was there. However, the conventional X
In the technology for forming the X-ray absorber pattern, if the X-ray absorber layer is made thicker, the aspect ratio (height of the pattern / dimension of the pattern) becomes larger, making it extremely difficult to form a fine pattern. There is a problem that the quality of the linear absorber pattern (dimensional accuracy, cross-sectional shape, etc.) deteriorates.

Further, in the pattern transfer of the X-ray exposure mask using the 1: 1 unity proximity exposure, if the pattern becomes finer, the resolution and the exposure amount margin are affected by the influence of X-ray diffraction and mutual interference. However, the exposure characteristics such as dimensional controllability deteriorate, which is a problem.

As a solution to such a problem,
Among the X-ray absorber patterns, an X-ray exposure in which the film thickness of an X-ray absorber layer corresponding to a pattern having a small planar size is made thinner than the film thickness of an X-ray absorber layer corresponding to a pattern having a large planar size. Masks have been proposed (JP-A-4-322).
419).

[0008]

However, in the conventional method of manufacturing a mask for X-ray exposure, since the processing is performed after depositing the heavy metal which is the X-ray absorber material, the fine pattern of the heavy metal is extremely formed. It is difficult to manufacture an X-ray mask having a high quality mask pattern shape.

Further, in the conventional X-ray exposure mask, since the peripheral portion of the mask pattern is formed by an X-ray absorber, the stress of the X-ray absorber film causes distortion in the X-ray exposure mask. There is a problem that the positional accuracy of the X-ray mask pattern deteriorates.

Further, when patterns of various sizes are mixed in the same mask, it is difficult to form the X-ray exposure mask by changing the film thickness of the X-ray absorber film according to the mask pattern size.

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to provide an X-ray exposure mask having a high quality mask pattern shape and a small mask distortion. That can be manufactured by various processes
It is to provide a method for manufacturing a line exposure mask.

Another object of the present invention is to provide a pattern having various sizes mixed in the same X-ray mask.
The X-ray absorber film has a smaller thickness for a fine pattern, and the X-ray absorber film has a larger thickness for a larger pattern.
An object of the present invention is to provide a method for manufacturing an X-ray exposure mask, which enables manufacturing of the X-ray exposure mask by a simple process.

[0013]

In order to achieve such an object, according to the present invention, the conventional method for manufacturing an exposure mask for X-rays is used up to the step of forming a membrane film which transmits X-rays on a silicon substrate. , An X-ray transparent film is formed on the membrane film, a resist is applied to the silicon substrate, a pattern is drawn, and the anisotropic X-ray is used by using the resist pattern as an etching mask for the X-ray transparent film.
After forming the X-ray absorbing pattern and sequentially depositing the X-ray absorbing film on the entire surface of the silicon substrate, the X-ray absorbing film is removed until the X-ray transmitting film is exposed to form the X-ray transmitting film. The mask for X-ray exposure is manufactured by leaving the X-ray absorber pattern only in the pattern portion.

In another invention, the resist pattern is set to X.
When the X-ray transparent pattern is formed by using anisotropic etching as an etching mask for the line transparent film, the micro loading effect is used, and the etching depth is changed according to the planar size of this resist pattern. The mask for X-ray exposure is manufactured by changing the film thickness of the X-ray absorber pattern according to the planar size of the pattern.

[0015]

In the present invention, since the X-ray transparent film is processed to form the X-ray absorber pattern, the process is easier than the conventional method for manufacturing an X-ray exposure mask, and the mask pattern with high accuracy is obtained. An X-ray exposure mask having a shape can be formed.

Further, since the X-ray absorber film around the X-ray mask pattern can be removed, it is possible to reduce the influence of the stress of the X-ray absorber film on the X-ray mask pattern position accuracy, and to improve the X-position accuracy of the X-ray mask pattern. A mask for line exposure can be manufactured.

Even when various dimensional patterns are mixed in the same X-ray mask, the X-ray absorber film is thin for fine patterns and X for large patterns by a simple process. It is possible to manufacture an X-ray exposure mask in which the film thickness of the line absorber film is increased, the effective exposure contrast in X-ray proximity exposure can be improved, and an X-ray exposure mask with high resolution can be obtained.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIGS. 1 to 8 are sectional views showing respective steps for explaining an embodiment of a method for manufacturing an X-ray exposure mask according to the present invention. In FIG. 1, first, a silicon nitride (SiN) membrane film 2 having a thickness of about 2 μm is formed on both front and back surfaces of a silicon substrate 1 having a thickness of about 2 mm by a low pressure CVD (chemical vapor deposition) method.

Next, as shown in FIG. 2, a silicon dioxide (SiO ₂ ) film 3 as an X-ray transparent film is formed on the surface side of the silicon substrate 1 as an X-ray transparent film by a plasma CVD method to a film thickness of about 0.6 μm. Formed. Next, as shown in FIG. 3, an EB (electron beam) positive resist film 4 was applied on the silicon dioxide film 3 to a film thickness of about 0.3 μm, and pattern drawing was performed by the EB exposure method and development was performed. . The drawn pattern has a line-and-space (L
& S) Pattern 5.

Then, the silicon dioxide film 3 was etched by anisotropic dry etching (RIE) using the L & S pattern 5 as an etching mask, and then the positive type resist film 4 was peeled off. In this case, in the RIE method for the silicon dioxide film 3, as shown in FIG. 4, the etching atmosphere and the etching time are controlled so that the etching depth of the silicon dioxide film 3 becomes about 0.6 μm of the initial film thickness. Just etched. As a result, an L & S pattern 6 of silicon dioxide having a size of about 0.3 μm could be formed.

Subsequently, as shown in FIG. 5, as an intermediate layer having good adhesiveness between the silicon dioxide film 3 formed on the silicon substrate 1 and the X-ray absorber layer formed in the subsequent step, the silicon substrate 1 is formed on the silicon substrate 1. Approximately 10 titanium (Ti) layers 11 are formed on the entire surface of the
nm thickness, titanium nitride (TiN) layer 12 is about 50 nm
The film was formed in this order with a film thickness of 1 by the sputtering method.

Subsequently, as shown in FIG. 6, a tungsten (W) layer 13 as an X-ray absorber layer was deposited to a thickness of about 1.0 μm on the entire surface of the silicon substrate 1 by a blanket CVD method. Then, the W layer 13 is flattened by CMP (Chemical Mechanical Polishing) until the surface of the silicon dioxide film 3 appears as shown in FIG. 7, and the X-ray absorber L &
The S pattern 14 was formed.

Next, as shown in FIG. 8, the SiN membrane film 2 on the back side of the silicon substrate 1 is etched by the RIE method, and the etched SiN membrane film 2 is used as a mask by the wet etching method using a KOH aqueous solution. A membrane window 17 was formed on the substrate 1, and finally the silicon substrate 1 was adhered to a Pyrex plate 18 to finally form an X-ray mask.

(Embodiment 2) FIGS. 9 to 16 are sectional views showing respective steps for explaining another embodiment of the method for manufacturing an X-ray exposure mask according to the present invention. In FIG. 9, first, for example, a silicon nitride (SiN) membrane film 2 is formed on both surfaces of a silicon substrate 1 having a thickness of about 2 mm under reduced pressure CV.
A film having a thickness of about 2 μm was formed by the D (chemical vapor deposition) method.

Next, as shown in FIG. 10, a silicon dioxide (SiO ₂ ) film 3 as an X-ray transmissive film is formed on the surface side of the silicon substrate 1 by the plasma CVD method to a film thickness of about 0.6 μm. Formed. Next, as shown in FIG. 11, an EB (electron beam) positive resist film 4 was applied on the silicon dioxide film 3 to a film thickness of about 0.3 μm, and pattern drawing was performed by the EB exposure method to develop. . The drawn pattern includes an isolated pattern 7 having a small planar size of about 0.1 μm and a large planar size of about 0.1 μm.
It is an isolated pattern 8 of 3 μm.

Next, anisotropic dry etching (RIE) is performed using these isolated removal patterns 7 and 8 as etching masks.
The silicon dioxide film 3 was etched by the method to peel off the positive resist film 4. Here, R of the silicon dioxide film 3
In the IE method, by controlling the etching atmosphere and the etching time as shown in FIG. 12, among the resist patterns of the resist film 4 described above, the silicon dioxide film 3 corresponding to the isolated removal pattern 8 having a large planar size is formed.
Was just etched so that the etching depth was about 0.6 μm of the initial film thickness.

When the silicon dioxide film 3 is etched by the above-mentioned RIE method, by utilizing the microloading effect, among the patterns of the silicon dioxide film 3 described above, the dioxide corresponding to the isolated pattern 7 having a small planar size is formed. The etching depth of the silicon film 3 is about 0.3.
It was formed to have a depth of 1/2 of the μm pattern. FIG. 17 shows the dimensional dependence of the etching rate of the silicon dioxide film 3 at this time. In FIG. 17, the etching rate is standardized.

As a result, as shown in FIG. 12, the dimension is about 0.1 μm and the etching residual film thickness T1 (μm) is about 0.
3 μm, etching depth film thickness T2 (μm) is about 0.3 μm
It can be formed as an isolated silicon dioxide etching pattern 9 of m and has a size of about 0.3 μm and a film thickness of about 0.6.
Silicon dioxide etching pattern without isolation of 10 μm 10
Could be formed as.

Subsequently, as shown in FIG. 13, the silicon dioxide film 3 formed on the silicon substrate 1 and the X-ray absorber layer to be formed in a later step serve as an intermediate layer having good adhesiveness. Approximately 10 titanium (Ti) layers 11 on the entire surface
nm thickness, titanium nitride (TiN) layer 12 is about 50 nm
The film was formed in this order with a film thickness of 1 by the sputtering method.

Subsequently, as shown in FIG. 14, a tungsten (W) layer 13 as an X-ray absorber layer was deposited to a thickness of about 1.0 μm on the entire surface of the silicon substrate 1 by a blanket CVD method. Then, the W layer 13 is flattened by CMP (Chemical Mechanical Polishing) until the surface of the silicon dioxide film 3 described above appears as shown in FIG.
The linear absorber patterns 15 and 16 were formed.

Next, as shown in FIG. 16, the SiN membrane film 2 on the back surface side of the silicon substrate 1 is etched by the RIE method, and the etched SiN membrane film 2 is used as a mask to etch the silicon by a wet etching method using an aqueous KOH solution. Forming a membrane window 17 on the substrate 1,
Finally, the silicon substrate 1 was adhered to the Pyrex plate 18 to finally form an X-ray mask.

In the first and second embodiments described above, silicon dioxide is used as the material of the X-ray transparent film, W is used as the material of the X-ray absorber film, and the X-ray transparent film and the X-ray absorber layer. Although an example in which TiN and Ti are respectively used as the intermediate layer having good adhesiveness with is described, the present invention can be achieved by using other combinations of X-ray transmissive material, X-ray absorber material and intermediate layer material. Is obviously applicable. Further, although the example in which the CMP method is used for processing the X-ray absorber film has been described, it is also clear that the etchback technique by etching can be used.

[0033]

As described above, according to the present invention,
Compared with the conventional manufacturing method of processing a heavy metal that is an X-ray absorber film, the processing becomes easier, the resolution can be improved, and an X-ray exposure mask having a highly accurate mask pattern shape can be formed. An extremely excellent effect can be obtained.

Further, since the X-ray absorber film in the peripheral portion of the mask pattern can be removed, the influence of the stress of the X-ray absorber film on the X-ray mask pattern position accuracy can be improved as compared with the conventional X-ray exposure mask. It is possible to reduce the number of masks, and it is possible to manufacture an X-ray exposure mask with high positional accuracy, which is an extremely excellent effect.

Further, even when patterns of various sizes are mixed in the same X-ray mask, the film thickness of the X-ray absorber film is thin for fine patterns and X for large patterns by a simple process. An X-ray mask having a thick absorber film can be manufactured, and the use of this X-ray exposure mask has an extremely excellent effect of improving the resolution.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a step illustrating an embodiment of a method for manufacturing an X-ray exposure mask according to the present invention.

FIG. 2 is a sectional view of a step following the step of FIG.

FIG. 3 is a sectional view of a step following the step of FIG.

FIG. 4 is a sectional view of a step following the step of FIG.

FIG. 5 is a sectional view of a step following the step of FIG.

FIG. 6 is a sectional view of a step following the step of FIG. 5;

FIG. 7 is a sectional view of a step following the step of FIG. 6;

FIG. 8 is a sectional view of a step following the step of FIG. 7.

FIG. 9 is a sectional view of a step illustrating another embodiment of the method for manufacturing an X-ray exposure mask according to the present invention.

FIG. 10 is a sectional view of a step following the step of FIG. 9;

11 is a sectional view of a step following the step of FIG.

12 is a sectional view of a step following FIG. 11. FIG.

FIG. 13 is a sectional view of a step following the step of FIG. 12;

FIG. 14 is a sectional view of a step following the step of FIG. 13;

FIG. 15 is a sectional view of a step following the step of FIG. 14;

16 is a sectional view of a step following FIG.

FIG. 17 is a diagram showing the dimensional dependence of the etching rate of a standardized silicon dioxide film.

[Explanation of symbols]

1 ... Silicon substrate, 2 ... Membrane film, 3 ... Silicon dioxide film, 4 ... Resist film, 5 ... Resist L & S pattern,
6 ... Silicon dioxide L & S pattern, 7 ... Small isolated resist pattern of planar size, 8 ... Large isolated resist pattern of planar size, 9 ... Small isolated silicon dioxide pattern of planar size, 10 ... Large silicon dioxide isolated pattern, 11 ... Ti
Layer, 12 ... TiN layer, 13 ... W layer, 14 ... X-ray absorber L
& S pattern, 15 ... X-ray absorber isolated pattern having a small planar size, 16 ... X-ray absorber isolated pattern having a large planar size, 17 ... Membrane window, 18 ... Pyrex plate.

Claims (2)

[Claims] 1. A method of manufacturing an X-ray mask having an X-ray absorber pattern on a silicon substrate, wherein the X-ray absorber pattern forms a X-ray permeable membrane film on the silicon substrate, After depositing an X-ray transparent film on the film, forming a window in the X-ray transparent film, depositing an X-ray absorber film on the entire surface of the silicon substrate, and then removing the X-ray absorber film by the X-ray absorber film. A method of manufacturing an X-ray exposure mask, comprising removing the X-ray transparent film until it is exposed, and forming an X-ray absorber pattern in the window of the X-ray transparent film. 2. A method of manufacturing an X-ray mask having an X-ray absorber pattern on a silicon substrate, wherein the X-ray absorber pattern forms a membrane film that transmits X-rays on the silicon substrate. After depositing an X-ray transparent film on the film, a resist film having at least two holes of different sizes is formed on the X-ray transparent film, and the X-ray transparent film is formed using the resist film as a mask. Etching is performed to form windows having different depths according to the size of the hole, and an X-ray absorber film is deposited on the entire surface of the silicon substrate. A method for manufacturing an X-ray exposure mask, comprising removing the film until it is exposed, and forming at least two X-ray absorber patterns having different thicknesses on the X-ray transparent film.