JPS61283122A - X-ray exposure mask - Google Patents

Abstract

PURPOSE:To accurately execute the accurate position measurement by providing a resist pattern obtained on a mask surface with X-ray absorber pattern as a mask or a pattern made of metal, inorganic material or polymer resin formed on the basis of the resist pattern. CONSTITUTION:An X-ray resist is coated on the surface of a conventional X-ray mask. Then, X-ray is emitted from the back surface side of the mask coated with the X-ray resist with an X-ray absorber pattern 1 as a mask. Then, it is developed as prescribed to obtain a resist pattern 5 on which an absorber pattern image is transferred. Information of an absorber pattern defect is also transferred to the pattern 5. Accordingly, the defect of the pattern 1 can be detected by detecting the deflect of the pattern 5 by the conventional defect detecting method. Even if the position of the pattern 1 is not directly measured, the accurate position of the pattern 1 can be evaluated by measuring the position of the pattern 5. Further, the accurate position measurement of the pattern 1 can be performed without removing a protective film 2.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an X-ray exposure mask, and in particular, to an X-ray exposure mask having a structure suitable for measuring the position of an absorber pattern and inspecting defects in the absorber pattern. This relates to an exposure mask.

[Background of the invention]

Regarding the structure of an X-ray exposure mask (hereinafter referred to as an X-ray mask), D. L. Spiers (D.

I,, 5pears), Henry I Sumi x (
Henr'/1, Sm1th) "No1i," by K.
Resolution: /, <Turn Replication Knee Jinx Softx Raise (High-Reso
lution PatternRep/1cation
Using 5 of X Rays)”, Electronics Letters, Vol. 8, No. 4, p. 102, 19
1972 (E! electronics Letters,
Vol, 8 A 4.

1) 102.1972). According to this, the X-ray mask is composed of two parts: an X-ray absorber pattern 1 and an X-ray transparent membrane 3 shown in FIG. Similar to conventional photolithography using ultraviolet light, this X-ray mask uses a predetermined absorber pattern to block the electromagnetic waves (X-rays) emitted from a light source (X-ray source), leaving a shadow on the wafer. It is used as a means of transferring images. Therefore,
As the X-ray absorber, Au, W, which has a high X-ray absorption rate,
A metal film such as Ta or Ni is used. The X-ray transmitting film 3 is generally called a membrane, and is composed of an extremely thin film such as BN%SiN4 with a thickness of about 1 to 3 μm. A support frame 4 is used to hold this. In addition, in recent years, a resin has been deposited on the X-ray mask for the purpose of preventing secondary electron emission from the absorber noturns and the membrane film (hereinafter, this deposited film will be referred to as protective film 2). ) X-ray mask
Yasunao Saito (YfiSunaO8aito)
“Submicron Pattern Replication Simin Using a High Contrast Mask and Tow Layer Resist in X-Ray Lithography” by et al.
n Replication Using a High
hContrast Mask and 1Ivo-l
ayer Re5ist in X-rayLitho
``Graphy)'', JASUK OF 'JR＊YUM SCIENCE TECHNOLOGY, B(2) 1. January - 3
May, 1984 (J, Vac, Sci, TeCk
lnO', +E(2)1mJan, -Mar,, 1
984).

The X-ray mask described above is made of materials and configurations that are very different from conventional optical masks. In other words, conventional quartz substrates that exhibit excellent transparency for ultraviolet light have wavelengths of several λ.
A thin film with a small atomic number (thickness of several μm or less) is used as the mask substrate (membrane) because it does not allow X-rays to pass through. On the other hand, conventional chromium, which exhibits sufficient UV-shielding properties, is not a satisfactory absorber for X-rays. Therefore, in order to obtain sufficient contrast of the absorber with respect to the X-ray transparent film, the above-mentioned metal with a large atomic number (Au, W, Ta, Ni, etc.) is used for the absorber.

With an X-ray mask having a structure different from the conventional photomasks described above, defects and particles made of elements with low atomic numbers on the mask are less likely to be transferred by X-rays. However, when an X-ray mask is put into practical use, it is necessary to remove defects such as missing or malformed absorber patterns that cause problems during transfer. However, if these defects are removed by optical means as in the case of conventional photomasks, all the defects that are problematic during X-ray transfer will be Undetectable. That is, even if there is a defect that poses a problem during X-ray transfer, it may not be detected by optical means, and conversely, even if it is detected as a defect by optical means, it may not pose a problem during X-ray transfer. Therefore, when making a conventional X-ray mask,
The use of conventional optical means to detect defects in masks is
The problem is that it cannot be done in practice.

In addition to the above problems, in the X-ray mask provided with the protective film 2 described above, there is a problem that highly accurate positional accuracy evaluation cannot be performed using the normally used method. In other words, conventionally, positional accuracy evaluation of X-ray mask patterns has been performed by scanning laser light and reading the reflected light intensity at the pattern edges, but when this method is applied to X-ray masks with a protective film, , the mask surface is flattened by laminating the protective film, so the detection signal S
/N becomes extremely poor and cannot be measured with high accuracy. Similar problems are often found in inspection processes during semiconductor manufacturing.

As a countermeasure to the above problem, it may be possible to remove the protective film in the pattern area to be measured, but as mentioned earlier, if there is no protective film, secondary electrons will be emitted from the KX-ray mask surface during X-ray transfer. For this reason, exposure with a high 7-ray contrast is not possible, so it cannot be used as is.Also, a method has been proposed in which a protective film is laminated after measuring the pattern position, but this method uses an X-ray mask for transfer. It will be impossible to measure the position accuracy again later.
In an absorber pattern such as the U pattern, the position detection signal is detected at the bottom and top of the pattern, resulting in a problem of poor measurement accuracy.

[Purpose of the invention]

An object of the present invention is to provide an X-ray mask that solves various problems of conventional X-ray masks, allows defect inspection of absorber patterns, and allows highly accurate position measurement even with a protective film. It is in.

[Summary of the invention]

The problems with conventional x-ray masks discussed above arise from the direct measurement of the x-ray absorber pattern on the x-ray mask by conventional optical means. Therefore, if a resist pattern formed using the X-ray absorber pattern as a mask exists on the X-ray mask surface, the information of the X-ray absorber will be transferred to this resist pattern as is, so this resist pattern We believe that it is possible to evaluate the X-ray absorber putter 7ftW, both indirectly, by detecting defects and positional accuracy using conventional optical means.

The present invention was made based on this idea,
Problems can be solved by providing a resist pattern obtained by using an X-ray absorber pattern as a mask, or a pattern made of metal, inorganic material, or polymer resin formed based on the resist pattern on at least one of both surfaces of the mask. This is an attempt to solve the problem.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

First, X made of BN held by the support frame 4 of Sl
On the radiation transmitting film 3 (membrane film), an X-ray absorber pattern 1 made of Au with a thickness of 1 μm and a protective film 2 (PIQ
A conventional X-ray mask is made by forming a conventional X-ray mask (NPR manufactured by Hitachi Chemical) on the surface of this X-ray mask. Next, from the back side of the X1II resist coated X-ray absorber pattern 1,
is used as a mask and irradiates X-rays with wavelengths of 5.4. Thereafter, a predetermined development process is performed to obtain a resist pattern 5 to which the absorber pattern image is transferred.

Since the resist pattern 5 is transferred by X-rays, information about absorber pattern defects, which are a problem only during X-ray transfer, is also transferred to the resist pattern 5. On the other hand, since this resist pattern 5 is usually made of the same material as the photoresist used for manufacturing semiconductor devices, conventional pattern defect detection methods can be used to detect defects.

Therefore, using the conventional defect detection method, the resist pattern 5
By detecting defects in the X-ray mask X-ray absorber pattern l, it is possible to detect defects in the X-ray mask X-ray absorber pattern l. This is a new function not found in conventional X-ray masks.

Further, the resist pattern 5 is the X-ray absorber pattern 1.
Since it is formed as a mask, the position accuracy of the X-ray absorber pattern 1 can be evaluated by measuring the position of the resist pattern 5 without directly measuring the position of the X-ray absorber pattern 1. Furthermore, since this resist turn 5 is formed on the protective film 2, the position accuracy of the X-ray absorber pattern 1 can be measured without removing the protective film 2. This is also a new function not found in conventional X-ray masks.

Note that the pattern described as resist pattern 5 in the above description does not necessarily have to be a resist pattern. That is, after forming the resist pattern, Step 7
Even if a new pattern made of metal, inorganic material, polymer resin, etc. is formed by etching or the like, the present invention can be practiced without any problem.

Furthermore, in the above embodiments, the resist pattern 5 was formed on the surface of the X-ray mask (on the protective film 2 side), but as shown in FIG. The invention is workable.

In addition, the resist pattern 5 related to the present invention has good X-ray transparency and will not cause any trouble to X-ray Ringer's fibrosis even if it is left as is after completing defect inspection and position accuracy measurement using this resist pattern. do not have.

FIG. 4 shows another embodiment of the present invention, in which a resist pattern 5 is formed on an X-ray absorber pattern in an X, 13 mask structure without a protective film. As mentioned earlier, the conventional X-ray mask structure without a protective film has the problem of secondary electrons being emitted from the mask surface, but in this structure, the X-ray absorber pattern 1 Secondary electron radiation from the resist pattern 5 can be prevented from being transmitted to the resist pattern 5. In addition, in the case of position accuracy measurement, the position of the X-ray absorber pattern 1 can be determined as shown in FIGS. 1 and 3 by measuring the resist pattern 5 without directly measuring the thick X-ray absorber pattern 1. As in the case of the example shown in FIG. is possible.

〔Effect of the invention〕

According to the present invention, in an X-ray mask, all defects in the X-ray absorber pattern are transferred to the resist pattern, and defects in the resist pattern can be detected by conventional defect inspection methods. can be detected almost completely. Further, even in an X-ray mask having a protective film, defects and positional accuracy can be evaluated with high accuracy according to the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing the structure of an X-ray mask according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view showing the structure of a conventional X-ray mask, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing the structure of an X-ray mask according to another embodiment. Explanation of symbols 1... X-ray absorber pattern 2... Protective film 3... X-ray transparent film (membrane film) 4... Support frame 5... Resist pattern

Claims (1)

[Claims] In an X-ray exposure mask composed of an X-ray mask membrane and an X-ray absorber pattern, at least one of both surfaces of the mask is provided with a resist pattern obtained by using the above-mentioned X-ray absorber pattern as a mask, or the resist pattern. X characterized by having a pattern made of metal, inorganic material or polymeric resin originally formed.
Mask for line exposure.