JPH01216529A - Manufacture of x-ray exposure mask - Google Patents

Abstract

PURPOSE:To shorten a beam radiating time, to shorten a working time, to reduce a damage on a primer, and to accurately form in shape an x-ray absorber pattern by correcting a mask layer pattern presented on an X-ray absorber layer. CONSTITUTION:An SiN film is formed as an X-ray transmission film 3 on one side face of an Si wafer for forming a mask supporting frame 5, an X-ray absorber layer 2 is formed on the face of the film, and formed on the layer 2 with an SiO2 film as a mask layer. Further, a resist layer pattern is formed on the mask layer, the mask layer is removed by dry etching with the resist layer pattern as a mask, thereby forming a mask layer pattern 1 for forming a circuit pattern. Then, a focused ion beam 6 is radiated to an SiO2 layer pattern 12 of a black defect to be removed by sputtering, thereby obtaining a corrected mask layer pattern 11. Thereafter, with the pattern layer as a mask a tantalum layer of a primer is removed by reactive ion etching, thereby obtaining an X-ray absorber pattern 21 having no pattern defect.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an X-ray exposure mask that can be applied to an XvAn optical device that transfers fine patterns with high precision.

[Conventional technology]

In recent years, X-ray transfer technology has come to be used for transferring fine patterns. As a method for correcting defects in order to manufacture a defect-free X-ray exposure mask, a method similar to the method for correcting defects occurring in light-shielding patterns in the conventional photomask manufacturing process has been attempted.

This repair method involves inspecting defects in the X-ray absorber pattern of the X-ray exposure mask after the pattern is formed, and then repairing the detected pattern defects by using a focused ion beam or laser beam. It is something to do. In this case, the pattern defect is the missing part of the pattern (
There are two types of defects: white defects (hereinafter referred to as white defects) and unnecessary portions of the pattern (hereinafter referred to as black defects).

For example, black defects in a pattern can be removed by sputtering by applying an ion beam to the black defects, or by evaporation by applying a laser beam to the black defects.

In addition, for white defects in patterns, for example, using an ion beam or a laser beam, a gas containing a heavy metal element with a large X-ray absorption coefficient, such as W (Co) &
A heavy metal element, in the above example, a method is performed in which W is deposited on white defects to form the necessary parts (hereinafter referred to as ion beam-induced chemical deposition method and laser beam-induced chemical deposition method, respectively). In addition, a method (hereinafter referred to as ion beam direct deposition method) in which the required pattern is formed by directly irradiating the X-ray transmitting area with an ion beam containing a heavy metal element having a large absorption coefficient for x* is also considered.

Hereinafter, these correction methods will be explained with reference to the drawings.

FIG. 3 is a diagram for explaining a method of manufacturing an X-ray exposure mask including a conventional black defect correction process.

In the figure, 1 is a mask layer pattern, 11 is a normal pattern, 1
2 is a black defect, 2 is an X-ray absorber layer, 21 is a normal XVa, accommodation pattern, 22 is an X-ray absorber pattern black defect, 3 is an X-ray absorber layer
A radiation transmitting film, 5 a mask support frame, 6 an ion beam or a laser beam, and 8 Htl (I).

Suppose that in the process of forming the mask layer pattern 1 (FIG. 3(a)), an unnecessary black defect 12 is detected in addition to the normal pattern 11. Using this pattern as a mask, remove the X-ray absorber layer 2 by, for example, reactive ion etching (Figure 3 (b)), then irradiate the black defect portion with an ion beam or laser beam 6 and perform sputtering or This is removed by evaporation (Figure 3 (c) and (d)).

This removal of black defects causes damage 8 to the X-ray transparent WA3. Then, by removing the mask support frame 5 except for a portion thereof by etching, an X-ray exposure mask with few pattern defects can be obtained.

FIG. 4 is a diagram for explaining a method of manufacturing an X-ray exposure mask including a conventional white defect correction process.

In the figure, the same numbers as in FIG. 3 indicate the same contents.

Note that 13 is a white defect, 23 is a white defect of the X-ray absorber pattern, and 24 is a corrected X-ray absorber pattern.

Suppose that in the process of forming the mask layer pattern 1 (FIG. 4(A)), a white defect 13 in which a necessary pattern does not exist is detected. As in the case of correction of the black defect in FIG. 3, for example, by reactive ion etching, the XvA absorber Il! 2
4(b)), then the ion beam-induced chemical deposition method, the laser beam-induced chemical deposition method,
A modified X-ray absorber pattern 24 is formed by an ion beam direct deposition method or the like (FIGS. 4(c) and (d)), and then,
By removing a portion of the mask support frame 5 by etching, an X-ray exposure mask with few pattern defects can be obtained.

[Problem to be solved by the invention]

However, since there is a large difference in structure between an X-ray exposure mask and a photomask, several problems arise with this correction method. The structure of the x#JAn light mask and photomask is as follows.

The configuration of the X-ray exposure mask includes an X-ray transparent film 3, an X-ray absorber pattern 21 formed thereon, and a mask support frame 5 that supports the X-ray transparent film.

The X-ray transmitting WA3 is made of a material with a small absorption coefficient for X-rays at the exposure wavelength, such as an inorganic material (SiN).

SiN:H, BN:H, BNC, C, SiC, 'TI)
% organic materials (polyimide, parylene) or their composite films are known, and their thickness is 0.9%. 3Bm to 6μm
It is.

On the other hand, the X-ray absorber 2 is made of a material having a large absorption coefficient for X-rays at the exposure wavelength, such as heavy metals and alloys thereof (Ta, W, W:Ti, WN).

Au) is used, and its thickness ranges from 0.3 pm to 1.5 pm.
It is 0 μm.

Since X-ray exposure masks are used to transfer fine patterns constituting large-scale integrated circuits, the minimum line width of the patterns is thought to be 0.2 μm to 0.5 μm. In the X-ray exposure mask and photomask, the aspect ratio of the pattern is H/W as shown in Figure 5. is the thickness (height) of the pattern), the pattern aspect ratio of the X-ray exposure mask used for fine pattern transfer is usually larger than 1. If N, W=
0.2pm-0.5pm, H-0.8)tm~Ipm
In this case, H/W=1.6 to 5.

On the other hand, a photomask consists of a substrate that is transparent to ultraviolet light and visible light, and a light-shielding pattern formed on the substrate, and the material of the light-shielding pattern is Cr, Mos.
+ etc., and the thickness H is 0.07am to 0.1a
m, and the pattern line width W is 0.3 μm or more, so the aspect ratio H/W is 0.3 or less. Moreover, glass or quartz is used for the substrate, and its thickness is 1 mm or more.

As described above, it can be seen that the XvA exposure mask is characterized by having a pattern with a large NMIt ratio on a very thin film compared to a photomask.

Therefore, in the conventional defect repair method as described above, xn
The following problems arise due to circumstances specific to n-light masks.

First, when correcting pattern black defects on the X&91 exposure mask by the prior art, that is, when removing unnecessary X-ray absorber patterns by ion beam or laser beam, the ion beam or laser beam There is a problem in that the X-ray transparent film around or under the pattern is also partially removed.For example, in the method of removing pattern black defects by evaporation using a thermal process such as a laser beam, the X-ray absorber is usually removed. The material has a higher melting point than the material of the X-ray transparent film and is more resistant to laser beams, so the laser beam irradiated to the X-ray absorber protrudes from the absorber pattern and damages the X-ray transparent film in the peripheral area. If the X-ray absorber is irradiated with the X-ray absorber, or if the X-ray transparent film underneath is irradiated immediately after the X-ray absorber is removed, the X-ray transparent film will be partially removed. The X-ray transparent membrane is originally transparent to X-rays, so even if it is damaged, it will not interfere with the transmission of X-rays. However, if even a portion of the membrane is damaged, its mechanical strength will decrease and it will be more likely to break. There is a problem in that stress concentration occurs locally, causing expansion and contraction, resulting in poor exposure accuracy.

A similar problem occurs with photomasks, but in the case of X&9 exposure masks, because the aspect ratio of the pattern is large, it is necessary to irradiate the laser beam for a long time to remove the pattern absorber. The fact that the X-ray transparent membrane is thin and susceptible to damage makes this a more serious problem.

Second, when correcting pattern white defects on X-ray exposure masks by conventional techniques, ion beam direct deposition method, ion beam induced chemical deposition method and the like.

Depending on the laser-induced chemical deposition method, there is a problem in that it is difficult to form an X-ray absorber pattern with an aspect ratio of 1 or more with good shape accuracy.

The present invention is intended to solve the above-mentioned problems.It shortens the beam irradiation time, shortens the work time, reduces TM damage to the base, and enables the formation of an X-ray absorber pattern with high shape accuracy. An object of the present invention is to provide a method for manufacturing an X-ray exposure mask.

[! ! ! Means to solve the problem]

As a result of various studies to solve the above problems, we found that instead of modifying the X-ray absorber pattern, we modified the mask layer pattern existing on the X-ray absorber layer in order to form an Xva absorber pattern. The present invention was completed by discovering that the above problems can be avoided by
The present invention is a method for manufacturing an XTJAn optical mask, which includes a step of forming a pattern on an underlying X-ray absorber layer using a mask layer formed on a patterned rod, and inspects the pattern of the mask layer for defects. The method is characterized by comprising the steps of: correcting the detected pattern defects in the mask layer; and forming a mask pattern on the X-ray absorber layer using the mask layer with the pattern defects corrected.

[Effect]

The method for manufacturing an X-ray exposure mask of the present invention includes inspecting a mask layer pattern for defects, correcting black defects and white defects detected at that time using appropriate methods, and patterning the defective mask layer pattern. By manufacturing an X-ray exposure mask with fewer defects by forming an X-ray absorber pattern after obtaining a The absorber pattern can be formed with high shape accuracy.

〔Example〕

Examples will be described below with reference to the drawings.

[Example 1] [Example 1] will be explained with reference to FIG.

A 5iNv film with a thickness of 0.5 μm to 2 pm is formed on one side of the Si wafer forming the mask support frame 5 by a low pressure chemical vapor deposition method as an X-ray transparent film 1i13, and a 5iNv film with a thickness of 0.5 μm to 2 pm is formed by a sputtering method on the film surface. After forming the X-ray absorber layer 2 made of a tantalum film with a thickness of 3 μm to 1 μm, an X-ray absorber H2 is formed using 5iOxa with a thickness of 0.1 μm to 0.37 μm as a mask layer by electron cyclotron resonance (ECR) plasma deposition method. formed on top of. Furthermore, after that, a resist layer pattern forming a circuit pattern is formed on the mask layer by electron beam engraving, and the mask layer is removed by dry etching using the resist layer pattern as a mask, as shown in FIG. 1(A). A mask layer pattern 1 forming a circuit pattern was formed (step 1).

Assume that when this mask layer pattern is inspected for defects, a black defect 12 as shown in FIG. 1(A) is detected (Step I[a).

Next, a focused ion beam 6 as shown in FIG. 1(B) is applied to the black defect Sin and the layer pattern 12 to remove it by sputtering, resulting in a modified mask layer pattern 11 as shown in FIG. 1(C). (Step ■a), more specifically, SiO
A square-shaped isolated black defect made of gN with a thickness of 0°25 pm and a side of Ipm is irradiated with a Ga" focused ion beam at a beam acceleration voltage of 30 kV and a beam current of 110 PA for about 1 second to remove the isolated black defect. It was possible to remove it by sputter etching.In addition, in this SiO film removal process, by detecting secondary ions or secondary electrons generated by focused ion beam irradiation, 5 toz
If the beam irradiation is stopped upon detecting that the tantalum film has been exposed by the removal of the tantalum film, it is possible to greatly reduce the extent to which the X-ray absorber layer 2 is removed by sputter etching.

Next, using the patterned layer as a mask, the underlying tantalum layer is CB
It was removed by reactive ion etching using rF5 gas, and an X-ray absorber pattern 21 free of pattern defects as shown in FIG. 1(d) could be obtained (Step IVa).
.

After that, while protecting the pattern part from coming into contact with the etch lag solution using a jig, the silicon at the bottom of the pattern part is heated to a temperature of 80° from the side opposite to the side where the X-ray absorber pattern is located.
An X-ray exposure mask with fewer pattern defects was obtained by etching and removing using a hydrium hydroxide aqueous solution containing 220% C20 (grainy percent) (step V).

By the way, the etching rate of tantalum, which is an X-ray absorber material, using a Ga''' focused ion beam is about the same as the etching rate of 510 gM!f, which is a mask layer material.Therefore, when repairing isolated black defects, Even if the ion beam protruded from a part of the 5iOxllllW pattern and irradiated the tantalum layer around the black defect, and the tantalum layer was partially removed and a depression with a depth of about 0.3 μm was created, in the next step IVa, the above-mentioned Since the etching rate of the X-ray transparent film SiN in reactive ion etching is less than 1/3 of the etching rate of tantalum, the depression with a depth of about 0.3 am in the tantalum film is at most about 0.1 II m deep in the SiN film. This is only a depression, and if the depression is of this size, it will not cause any practical problem.Furthermore, if the above-mentioned secondary ion and secondary electron detection is used in conjunction with the beam irradiation stop, damage to the XI transmission membrane can be almost eliminated.

[Example 2] In the example described in Example 1, the following process was performed instead of process ma as a method for removing black defects in the mask layer pattern.

That is, by irradiating the black defect 12 of the mask layer pattern with a rectangular laser beam, Si forming the black defect is removed.
O*FJ was removed by evaporation to obtain a modified mask layer pattern as shown in FIG. 1(c) (step mb). Note that since the base of the mask layer is a tantalum layer which is a high melting point metal, the amount of the tantalum layer that was evaporated and removed was small.

Thereafter, Step IVa and Step V described in Example 1
Using this method, an X-ray exposure mask with few pattern defects was obtained.

[Example 3] A mask layer pattern was formed using the process described in Example 1. Next, defects in this mask layer pattern were inspected, and white defect portions 13 were found as shown in FIG. 2(A). Suppose that is detected (Step ①C).

Next, as shown in Figure 2 (b), while spraying pyrene gas onto the tantalum surface of the white defect area, a Ga'' focused ion beam is irradiated onto the white defect area based on the ion beam induced chemical deposition method. A pattern of a predetermined shape with a thickness of 0.3 μm is formed using carbon (Step 11 [c).

In this way, a modified mask layer pattern 14 as shown in FIG. 2(c) was obtained. More specifically, for a square isolated white defect whose -side is lam, a beam acceleration voltage of 30
By irradiating the tantalum layer in the white defect area with a Ga''' integrated ion beam having a current of 130 PA and a heating current of 130 PA for 4 seconds, a thickness of approximately 0.3 pm with a side of 1 pm was formed.
Next, as in Example 1, using the normal mask layer pattern 11 made of Sin and the modified mask layer pattern 14 made of carbon as masks, CBrF was formed. , the tantalum N2 was removed by reactive etching using gas to obtain a modified xl absorber pattern as shown in FIG. X$l with fewer defects in the X-ray absorber pattern! !
An exposure mask was obtained.

Note that as another example of white defect correction, a correction pattern may be formed by an ion beam direct deposition method.

Further, in Examples 1 to 3, tantalum was selected as the X-ray absorber material and Sin was selected as the mask layer material, but the method of the present invention is not limited to these materials.

Incidentally, the present invention is applicable even if the mask layer material is an organic resist layer. However, in many cases, inspection and correction of organic film patterns are more difficult than inspection and correction of inorganic layer patterns described in this embodiment.

Further, in Examples 1 to 3 above, isolated defects were explained, but as shown in FIG.
Any defect is fine.

In Figure 6, A is a cut, B is a tangerine cut, C is a hollow, and D
Denotes a defect consisting of a protrusion, E a white dot (pinhole), and F a black dot. These defects can be corrected by scanning and beam irradiation using an appropriate method such as raster scanning or vector scanning.

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be obtained.

■In the correction of white defects in patterns, it is easy to correct them because it is only necessary to form a pattern with a smaller aspect ratio compared to the conventional technique, and this is because the pattern line width W is small (remarkable 0 For example, W = 0 In the case of .2pm, the aspect ratio H/W in the conventional technology is 4(T(-0.8μm),
The aspect ratio H/W in the present invention is 1.3 (H=0.25μm
), making pattern formation easier.

(2) In correcting black defects in a pattern, since the aspect ratio of the pattern is smaller in the present invention, the beam irradiation time is shorter and damage to the underlying layer is slight.

■Working time can be reduced for both white and black defects.

(2) Both black and white defects in the mask layer pattern can be repaired in the same repair device using a focused ion beam or laser beam, depending on whether or not a chemical deposition gas is sprayed.

That is, by direct beam irradiation without gas spraying, black defects are corrected by etching, and by beam irradiation while gas spraying, the defects that are adsorbed on the surface of the X-ray absorber layer are removed. ionize and deposit gas,
A correction pattern can be formed and corrections can be made very easily.

Furthermore, by using a focused ion beam or laser beam irradiation, a pattern with good shape accuracy can be obtained.

■In the correction of pattern white defects according to the present invention, the material of the pattern to be formed is not limited to X-ray absorber materials, such as heavy metals, and various materials can be selected as long as they are resistant to etching against reactive gases. .

For example, Cs S 10t s S i N%SiC, etc. are known.

(2) Since the defect repair of the present invention involves repairing the mask layer, it is easy to re-fix even after the defect has been repaired twice.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a method for manufacturing an X-ray exposure mask including a process of correcting black defects in a mask layer pattern according to the present invention, and FIG. A diagram for explaining a method for manufacturing a mask for line exposure, and FIG. 3 is a diagram showing a conventional method for manufacturing an xtan-filled mask, including a process for correcting black defects of X*@container caused from black defects in a mask layer pattern. , Fig. 4 is a diagram showing a conventional manufacturing method for an X-ray exposure mask, including a process of correcting white defects in the X-ray absorber caused by white defects in the mask layer pattern, and Fig. 5 is an explanation of the aspect ratio of the pattern. FIG. 6 is a diagram for explaining types of defects. 1... Mask layer pattern, 2... X-ray absorber layer, 3
. . . X-ray transmission film, 5 . . Mask support frame, 6 .
・White defect in mask layer pattern, 14... Corrected mask layer pattern, 21... Normal X-ray absorber pattern, 22... Black defect in X-ray absorber pattern, 23...
White defect in ray absorber pattern, 24... Corrected X-ray absorber pattern.

Claims (4)

[Claims] (1) A method for manufacturing an X-ray exposure mask, which includes a step of forming a pattern on an underlying X-ray absorber layer using a mask layer formed in a pattern, the method comprising forming a pattern on the mask layer with defects. A method for manufacturing an X-ray exposure mask, comprising the steps of inspecting, correcting detected pattern defects in a mask layer, and forming a mask pattern on an X-ray absorber layer using the mask layer with the pattern defects corrected. (2) A claim in which the mask layer pattern is a black defect, and the beam irradiation is stopped at the same time as the X-ray absorber layer is exposed by detecting secondary ions or secondary electrons generated when the black defect is removed by ion beam sputtering. 1. The method for manufacturing an X-ray exposure mask according to 1. (3) Claim 1, wherein the mask layer pattern is a black defect, and the black defect is removed by irradiating with a shape-shaped laser beam.
The method for manufacturing the X-ray exposure mask described above. (4) The X-ray exposure method according to claim 1, wherein the mask layer pattern is a white defect, and the white defect is corrected by a laser beam-induced chemical deposition method, an ion beam-induced chemical deposition method, or an ion beam direct deposition method. How to make a mask.