JPH0214511A - Mask for x-ray exposure use and its manufacture - Google Patents

Abstract

PURPOSE:To prevent an inconvenience such as a fog or the like during a developing operation by a method wherein a metal foil layer with a desired thickness is formed at an outer periphery of a unit exposure region in order to form the unit exposure region densely. CONSTITUTION:A silicon nitride film 2 both as an X-ray transmitting thin film and as a protective film is formed on both faces of a silicon wafer 1 forming a sheet-like substrate; after that, a tungsten film as an X-ray absorbing thin film 3 is formed on one face of the sheet-like substrate. Then, one part of the silicon nitride film 2 on the rear surface of the sheet-like substrate is removed; a window 4 for back-etching use in formed; a resist is formed on the surface; the X-ray absorbing thin film 3 is patterned. Then, a transcription sheet 8 formed by successively laminating an adhesion layer 5, a gold foil 6 and an exfoliation paper 7 which have been stamped in advance to a shape prescribing a unit exposure region is piled up in a prescribed position; the exfoliation paper is stripped off; a gold foil layer is formed at an outer periphery of the unit exposure region. Then, silicon is removed from the window 4 for back-etching use; an opening part 9 is formed; a mask for X-ray exposure use is obtained. Then, the unit exposure region can be formed densely.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an X-ray exposure mask and a method for manufacturing the same.

(Prior art) - An X-ray exposure mask consists of a heavy metal pattern that absorbs X-rays, a light element film that supports the heavy metal pattern and that absorbs less X tit, and a film that fixes the outer periphery of the film. ing.

Heavy metal patterns that absorb X-rays include Au, TaW, and PLl.
Composed of motes with large atomic numbers such as Mo, Re, etc., and has a thickness of 0.
．． A fine circuit pattern of 2 to 3 μm is formed.

The film supporting the heavy metal pattern is made of an X-ray transparent thin film of SiN, BN, SiC, Be, polyimide, etc. with a jI of 0.1 to 5 μm.

The frame material is made of a relatively rigid material such as Si that can be removed by etching and has a thickness of 0.3 to 3 .mu.m, and has a window containing an exposed area such as a circuit.

In X-ray exposure, the substrate on which the resist hi to be exposed is formed is irradiated with X-rays through such an X-ray exposure mask, thereby forming a pattern on the resist layer.

(Problem to be Solved by the Invention) In X-ray exposure, in order to apply a large number of identical patterns onto a relatively large substrate to be exposed, the pattern is formed on each chip by sequentially moving the mask or substrate. A so-called step-and-repeat method is used.

Generally, in order to define the unit exposure area, an X-ray absorbing layer that is the same layer and has the same thickness as the X-ray absorbing metal pattern is formed on the outer periphery of the area.

However, at the outer periphery of each unit exposure area, a small amount of X-rays overlap each time each unit area is exposed. Of course, there would be no problem if this area was originally irradiated with X-rays only once, but due to phenomena such as leakage and diffraction, the contrast with the area that was originally irradiated with X-rays was not created, and the number of X-rays was irradiated twice. If the areas overlap more than this, it becomes difficult to distinguish between the areas that are originally irradiated with X-rays, and problems such as fogging occur during development.

The present invention overcomes the drawbacks of the prior art and proposes a novel XvA exposure mask and method for manufacturing the same.

(Means for Solving the Problems) That is, the present invention provides an An X-ray mask characterized in that a metal foil layer of a desired thickness is formed on the outer periphery of a unit exposure area without or through an adhesive layer, and on the main surface of a plate-shaped substrate. a step of laminating an X-ray transparent thin film on the substrate, forming a protective film on the other surface in a portion corresponding to the lower surface of the support frame; and a step of forming an X-ray absorbing metal pattern on the XM-transparent film. , a process of etching away a desired area of a plate-shaped substrate from the opposite side of the main surface to form a window, and a process of forming a metal foil layer or an adhesive layer and a metal foil layer by transfer on the outer periphery of the unit exposure area. This is a method for manufacturing an X-ray exposure mask.

The present invention will be explained in more detail below.

X-ray absorbing metal patterns include Au, Ta, W, Pt, MO
, Re, etc. The X-ray transparent support is made of SiN BN, SiCBe polyimide, etc. The support frame is mainly made of silicon.

A metal foil such as gold foil is formed on the outer periphery of the X-ray absorbing metal pattern that defines the exposure area. In this case, an adhesive layer may or may not be necessary. In addition, the method for manufacturing the X-ray mask of the present invention is to first form an X-ray transparent thin film on the main surface of a tile-shaped substrate (such as a silicon wafer) and a protective film on the other surface. Even if it is provided on the side surface, etc., it is just a device within the scope of the design.

X-ray transparent thin films such as SiN, BN, SiC, and Be can be produced using thin film formation methods such as chemical vapor deposition, physical vapor deposition, and sputtering, such as PVD (physical deposition method) and CVD (chemical deposition method). Each method can be used.

In addition, polyimide is formed by coating, film adhesion, etc.

In addition, the SiN, 5int, and SiC protective films are formed in the same process as the X-ray transparent thin film or in a separate process, and the portion corresponding to the window opening in the substrate is formed in the same way as the X-ray transparent thin film. It is removed by patterning means such as dry etching. Therefore, if they are made of the same material, they may be formed at the same time. The areas to be formed at that time are the main surface, the other surface, and the side surfaces as necessary.

Next, an X-ray absorbing metal pattern is formed on the X-ray transparent thin film. X-ray absorbing metals Au, Ta, WPt, Mo, R
e, etc. are physical vapor deposition, sputtering, electroplating, etc.
It is formed by various methods such as VD (physical deposition method) and CVD (chemical deposition method).

Various methods can be used for patterning, but for boat fishing, it is carried out either by a subtractive method in which the metal layer is formed in advance and then shaped into a pattern, or by an additive method in which a metal layer is deposited in a pattern shape. In the subtractive method, a pattern resist is formed on the metal layer, and a pattern is formed by dry etching or the like. In the additive method, a conductive film is formed on a transparent thin film, a pattern resist is formed on top, a metal pattern is formed by plating, and then unnecessary parts of the conductive film are removed by dry etching, etc. . Next, a metal foil having a predetermined unit exposure area opened is formed on the main surface of the substrate.

There are various possible manufacturing methods such as screen printing, gravure printing, PVD (physical film deposition) methods such as vapor deposition and sputtering, but considering the influence on the main surface of the substrate, defects, ease of manufacture, etc. Transfer formation is most suitable.

Although there are various types of transfer, it is common to stack a patterned metal foil transfer sheet on the main surface of the substrate and transfer it to the outer peripheral surface defining a unit exposure area on the main surface of the substrate. Note that the adhesive may be pre-formed on the metal foil transfer sheet, pre-formed on the mask, or may be omitted depending on the adhesive strength of the metal.

Further, patterning using either metal foil or adhesive is sufficient, and patterning using an adhesion inhibiting layer may be sufficient. The metal foil to be transferred is 1 to 10 μm Au, Ta.

W, PL, Mo, Re, etc. are commonly used, but the thickness etc. need not be limited to these values. In addition, the transfer sheet is a release paper,
It can be easily obtained by laminating or vapor depositing the metal foil on a releasable sheet such as a synthetic resin sheet to form an adhesive layer. Hereinafter, this case will be explained in detail.The portion of the unit exposure area where the metal foil is not used can be punched out of the transfer sheet to open the unit exposure area. Alternatively, unnecessary portions can be removed by etching in advance without punching.

Next, in the step of forming a desired window on the plate-shaped substrate, the window is formed by etching the plate-shaped substrate in a desired shape from the surface provided with the protective film.

(Function) In the present invention, a metal foil is formed on the outer circumferential surface of the unit exposure area that defines the unit exposure area, and this metal foil sufficiently absorbs the X-rays irradiated outside the unit exposure area, resulting in three effects. Using the X-ray exposure mask of the present invention while leaving a sufficient amount of X-rays,
Even if you are exposed to a small amount of X-rays several times when exposing unit areas on the exposed substrate using the step-and-repeat method, the amount of X-ray exposure is negligible, compared to conventional X-rays.
It is possible to avoid the inconvenience of fogging or the like occurring in the boundary area as in the case of a line mask.

In addition, in the manufacturing method, especially when it is formed by transfer, it is highly effective in preventing the occurrence of defects that would otherwise have physical or chemical effects on the main surface of the substrate. Also, it is easier to manufacture than the pond method.

(Example 1) FIG. 1 shows an example of manufacturing an X-ray exposure mask according to the present invention.

First, as shown in Figure 1a), the plane orientation (
A silicon nitride film 2, which is an X-ray transparent thin film and also a protective film, is formed on both sides of the silicon wafer 1 of 110) to a thickness of 2 μm by a chemical vapor deposition method, and then by a reactive sputtering method. As shown in Figure 1b), the X-ray absorbing thin film 3
A tungsten film having a thickness of 1 μm is formed on one side of a plate-shaped substrate.

Next, as shown in FIG. 1C), a part of the silicon nitride film 2 on the lower surface of the plate-shaped substrate is removed by dry etching to form a pack etching window 4, and a resist is formed on the upper surface by electron beam exposure. Then, the X-ray absorbing thin film 3 is patterned by reactive ion etching.

Next, as shown in FIG. 1d), a transfer sheet 8, which has been punched out in advance into a shape that defines a unit exposure area and is laminated with adhesive 15, gold':n6, and release paper 7 in this order, is placed in a predetermined position. , the release paper is peeled off and a gold foil layer is formed on a predetermined area corresponding to the outer periphery of the unit exposure area.

Next, as shown in FIG. 1e), the bank etching window 4 is etched.
So, alkaline water? Silicon is removed using liquid No. 8, and openings 9 are formed to obtain an X-ray exposure mask according to the present invention.

(Example 2) FIG. 2 shows another manufacturing example of an X-ray exposure mask according to the present invention.

First, as shown in Figure 2a), the plane orientation (
After forming a silicon nitride film 2, which is an X-ray transparent thin film and also a protective film, to a thickness of 2 μm on both sides of the silicon wafer 1 shown in FIG. As shown in b), a tungsten film as the X-ray absorbing thin film 3 is formed to a thickness of ltlm on one side of the plate-shaped substrate.

Next, as shown in FIG. 2C), the silicon nitride film 2 on the bottom surface of the substrate is
At least a portion including the exposed area is removed by dry etching to form a back etching window 4, a resist is formed on the upper surface by electron beam exposure, and an X-ray absorbing thin film 3 is patterned by reactive ion etching. . The three patterns of the X-ray absorbing thin film are only in the exposed area.

Next, as shown in Figure 2 d), the back etching window 4 is
Then, silicon is removed using an alkaline aqueous solution to form an opening 9.

Thereafter, as shown in FIG. 2e), a transfer sheet 8, which has been punched out in advance into a shape that defines a unit exposure area and has an adhesive layer 5, gold foil 6, and release paper 7 laminated in this order, is superimposed at a predetermined position. , peel off the release paper 7 and form the gold foil 6 on a predetermined area.

(Effects of the Invention) Since the X-ray exposure mask according to the present invention has a sufficiently thick transfer metal layer formed on the outer periphery outside the unit exposure area,
The manufacturing method of the present invention allows unit exposure areas to be densely packed and formed, and the manufacturing method of the present invention uses an extremely simple method of transferring metal foil without modifying the conventional fine pattern forming process. , an X-ray shielding frame can be formed.

[Brief explanation of the drawing]

Figures 1 a) to e) are cross-sectional views sequentially showing the steps of one embodiment of the present invention, and Figures 2 a) to e) are cross-sectional views sequentially showing the steps of another embodiment of the present invention. It is a diagram. Wafer 2: silicon nitride film X-ray absorbing thin film, window: adhesive layer; gold foil: release paper: transfer sheet; adhesive layer

Claims (1)

[Claims] 1) An X-ray mask consisting of a heavy metal pattern that absorbs X-rays, a film of a light element that absorbs little X-rays that supports the heavy metal pattern, and a frame that fixes the outer periphery of the film, An X-ray mask characterized in that a metal foil layer is formed on the outer periphery of a unit exposure area with or without an adhesive layer. 2) A step of laminating an X-ray transparent thin film on the main surface of the plate-shaped substrate and forming a protective film on the other surface in a portion corresponding to the lower surface of the support frame, and a step of laminating an X-ray absorbing thin film on the X-ray transparent thin film. a process of forming a transparent metal pattern, a process of etching away a desired area of the plate-shaped substrate from the opposite side of the main surface to form a window, and a process of forming a metal foil layer or an adhesive layer and a metal foil by transfer on the outer periphery of the unit exposure area. A method for manufacturing an X-ray exposure mask, which comprises a step of forming a layer. 3) A step of forming an X-ray transparent thin film and protective film on the main surface and the other surface of the plate-shaped substrate at portions corresponding to the lower surface of the support frame, and
A step of forming an X-ray absorbing metal pattern on the main surface of the radiation-transparent thin film/protective film, a step of etching away a desired area of the plate-shaped substrate from the opposite side of the main surface to form a window, and a unit exposure step. A method for manufacturing an X-ray exposure mask comprising the steps of forming a metal foil layer or an adhesive layer and a metal foil layer on the outer periphery of a region by transfer.