JPS6113621A - Pattern forming method - Google Patents

Abstract

PURPOSE:To prevent the unsatisfactory configuration generated at manufacturing an absorption pattern to be used for an X-ray exposure mask by a method wherein a metal or an alloy layer which is hardly sputtered is provided on the surface of an Au electrode which is susceptible to sputtering. CONSTITUTION:A Ti thin film 8 is vapor-deposited on an Au electrode plate to be used for plating, a Cr mask 5 is superposed on a resist 1, and an O2 sputter- etching is performed. Subsequently, Au is electrolytically plated, and an excellent absorber pattern 3 having no protrusion is formed. Besides, when non-electrolytic plating is performed, the same efficiency as above-mentioned can be obtained. Also, when Cr, Fe, Mo, Nb, Ni, Ta and the like having excellent anti- sputtering property when compared with Au are laminated, the same efficiency as Ti can be obtained, and the unsatisfactory configuration generating when an absorber pattern is formed can be prevented almost completely. A highly precise exposure can be performed using this pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] 1. The present invention relates to a pattern forming method, particularly.

Suitable for producing absorber patterns for X-ray exposure masks.

The present invention relates to a pattern forming method.

[Background of the invention]

In recent years, with the increase in the density of semiconductor integrated circuits and the high integration 2゜area ratio, fine patterns with extremely small line widths and spacings have become available.

- There is a method that allows easy formation of ridges with high precision.

First of all, it became necessary.

However, lithography is currently in practical use.

(b) (Using ultraviolet light with a wavelength of 320 to 5QQ nm), the limit is a pattern size of 05 μm or more.

However, it is not possible to form patterns with dimensions smaller than this.

There is a problem. For this reason, a new ring has been created to replace it.

An X-ray lithography method was proposed as a method for lithography.

It is. In the 1° X-ray phosphorography method, X-rays, which have a much shorter wavelength than normal ultraviolet light, are used for pattern transfer.

By this, an ultra-fine pattern of 0.5 μm or less is formed.

It is believed that this can be done.

By the way, in this X-ray lithography,

Since there is no optical system between the screen and the wafer, the dimensions and shape of the absorber pattern on the X-ray mask are transferred onto the wafer almost unchanged. Therefore,.

In order to obtain an ultra-fine pattern on a wafer, it must be formed on a hardened X-ray mask.

It is necessary to fabricate the absorber pattern with an accuracy equivalent to or better than that of the - However, the absorber pattern.

2, and as detailed below.

A problem arose.

Here, a method conventionally used in order to produce an absorber pattern will be explained with reference to FIG. First, plate the electrode plate 2'' by a predetermined process.

An electron beam or ultraviolet light resist pattern 1 is formed (FIG. 2(a)), and then this resist pattern 1 is formed.

Electrolytic plating or electroless plating using as a mask 1ft
(hereinafter simply referred to as plating) absorber pattern 3
The resist pattern 1 was formed (FIG. 2(B)), and the resist pattern 1 was removed as necessary (FIG. 2(C)).

However, with this method, the cross-sectional shape of the resist pattern 1 is difficult to be vertical, so the obtained absorber pattern 1°
A phenomenon occurred in which the cross-sectional shape of the pattern differs in size between the upper part α and the lower part β of the pattern, as shown in FIG.

In contrast, a new pattern formation method (Ono et al. 2: Reactive ion etching of polyimide films: miscellaneous).

Magazine ``Shinku J 1982 Vol. 25 No. 9 (605)) proposed.

It is. As shown in Fig. 3, this method involves laminating a lower resist (resin film) la, an intermediate layer 5, and an upper resist 4 on the plating electrode plate 2 (Fig. 3(a)). The so-called multi-layer resist process proposed in Japanese Patent Publication No. 58-51412 (same figure (bl, (C))
At.

Form a pattern and use this pattern as a mask.

((d) in the same figure) to form absorber pattern 3.

((e) in the same figure).

According to this method, it becomes a mask during plating.

The cyst pattern does not depend on the normal photosensitive process.

It is formed by dry etching (FIG. 3(C)).

Therefore, the cross section of the pattern is perpendicular to the electrode plate surface.

It has the advantage of being Therefore, this resist pattern.

If plating is performed using the -n as a mask, an absorber pattern 3 having a vertical cross section of 1° can be similarly obtained. This eliminates the dimensional difference between the upper and lower parts of the pattern, which was a problem with conventional methods, resulting in a highly accurate absorber pattern.

Now you can get it.

However, a new problem arose. Su2゜・
3. That is, the problem is that protrusions grow at the ends of the absorber pattern due to dry etching during plating mask pattern preparation.・Hereafter, Part 4
This problem will be explained using a diagram.・The figure (a) is
This figure shows how the resist (resin) film (la) is etched by oxygen sputtering using the intermediate layer 5 as a mask.

The state shown in the figure is just before the end of etching, and the resist (resin film) la is in the desired area.

It has been removed and the electrode plate 2 is exposed. However, this...

At this time, the oxygen ions directly reach the exposed electrode plate 2 by 1° and sputter the surface of the electrode plate, and as a result, particles of the sputtered electrode plate material adhere to the side surface of the pattern of the resist 1a.
The same figure shows the formation of the electrode plate material reattachment layer 6.

(a)) The resulting resist pattern l.

When plating is performed using a mask, the adhering electrode plate material re-deposition layer 6 becomes a new part of the electrode (in the case of electroless plating, the body to be plated), and the protrusion 7 grows.

(Figure (b)). So, you finally get it.

A protrusion 7 remains at the end of the absorbent pattern 3 that has been removed.

((C) in the same figure), X-ray exposure using this pattern as a mask.
.

・　4　・ When exposed to light, X-rays are transmitted through areas where the film is thin.

Therefore, it is said that highly accurate transfer patterns cannot be obtained.

A problem arose.

[Purpose of the invention]

The object of the present invention is based on a multilayer resist process.

Plating electrode during plating mask pattern creation.

This reduces the sputtering effect on the plate surface.

Solve the problem of protrusions growing during plating.

Absorber pattern for X-ray exposure mask.

Another object of the present invention is to provide a forming method. 1゜〔
Summary of the invention In the past, Au has generally been used as a material for plating electrodes (in the case of electrolytic plating) for reasons such as conductivity.
As is well known, Au has the property of being highly susceptible to sputtering. Therefore, we thought that if a layer of another metal or alloy that is difficult to sputter is provided on the surface of the Au electrode, the electrode material will hardly be sputtered even if this layer is used as an electrode (in the case of electrolytic plating).

The present invention was made based on this idea,
Electrolyte is used for sputter etching.

Electrodes for electroless plating or coatings for electroless plating.

In order to reduce the sputtering effect in the electrode plate material that becomes the plating body, at least the surface of the electrode plate is coated with Cr, Fe, or the like.

Metals that are difficult to sputter, such as Mo, Nb, Ni, Ta, Ti, and alloys containing these as main components.

is made of an alloy.

[Embodiments of the invention]

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

ru0+L1 First, as shown in FIG. 1(a), for plating Au.

On the electrode plate 2, a new TI thin film 8 was deposited to a thickness of 20OA.
.

The resist for resist pattern l (
PIQ (manufactured by Hitachi Chemical) was used as the resin film.

The thickness is 1.5 μm, and the intermediate layer 5 is made of Cr with a thickness of 500 μm.
,.

Each layer is laminated in the hole, and then the intermediate layer 5 of Cr is applied.

As a step, a resist pattern 1 was formed by oxygen sputter etching (multilayer resist process). During this oxygen sputtering, the sputtering rate of Ti with respect to oxygen ions is 2, compared to that of Au.

It is extremely minute and does not adhere to the resist pattern 1.

It is considered to be inconceivable. Therefore, the same figure (bl.

As shown, this resist pattern l is used as a mask.

and plating conditions.

Plating solution Newtronex 210 manufactured by Nippon Electroblating Engineers.

When Au was plated by electrolytic plating at a current density of 4 mA/(7) and a liquid temperature of 65° C., a good absorber pattern 3 with no protrusions was obtained as shown in FIG. 3(C).

In the above example, the T1 thin film was intentionally not removed before plating. This is because the plating mask pattern easily peels off when removing the T1 thin film, and because Ti causes some kind of reaction with Au during evaporation.
This is because it is difficult to remove. This phenomenon was observed in Cr, Mo, etc. in addition to Ti, but there was no problem in plating even if no particular removal was performed.

In addition, in the above embodiment, when plating Au, As mentioned above, plating with Ni, Ag, etc. other than Au.

Also, the present invention has no problems with implementation.

It was.

In addition, in the second embodiment, when electrolytic plating is performed.

However, it has been confirmed that the present invention has similar effects in the case of electroless plating.

In the above embodiment, the electrode plate is made of Au as a base material.

The case where a TI thin film is laminated on the surface will be described.

Ta. Therefore, like Ti, it is more resistant to spatter than Au.

Cr, Fe, Mo, Nb, Ni, with excellent properties
The effect of the present invention was confirmed by laminating Ta or the like at an angle of 11°.

Also, in the example described above, the electrode plate is on the base metal.

Cr, Fe, Mo, Nb, Ni, Ta, T
It has a structure of 6 layers of metals such as i, but the poles are made of only these metals.

Even if a plate is used, the present invention can be carried out without any problems. .

It was confirmed.

In the above embodiments, the shape of the resist pattern.

The resist (resin film) is etched by oxygen sputtering.

We have described the case where this is done by CF4/CC1
, , using other gases such as Ar, or mixed gases thereof.

・　8　・ The present invention applies even when sputter etching is performed.

is equally valid.

Specifically, the X-ray absorber pattern is created using a plating method.

Once formed, the pattern is traditionally a membrane at the center and edges.

Although the difference in thickness was about 100 nm to 2000 nm, it was not possible with the present invention.

With the method described above, this can be reduced to approximately Qnm.

Ta.

〔Effect of the invention〕

According to the present invention, an absorber butter for an X-ray exposure mask.

-Almost completely prevents shape defects that occur during production.

This allows the X-ray absorption rate to be made uniform within this pattern, resulting in highly accurate X-ray transfer (exposure).
becomes possible.

[Brief Description of the Drawings] Fig. 1 is a schematic cross-sectional view of a sample for explaining an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view of a sample showing a pattern forming method using a conventional plating method, and Fig. 3 is a schematic cross-sectional view of a sample illustrating a pattern forming method using a conventional plating method. A schematic cross-sectional view of a sample showing a pattern forming method using a plating method proposed to improve this conventional method, and FIG. 4 shows problems in the pattern forming method shown in FIG. 3. FIG. 3 is a schematic cross-sectional view of a sample for explaining the points. Explanation of symbols 1...Resist pattern 1a...Resist (resin film) 2...Plating plate 3...Pattern absorber 4.
..." Two-layer resist 5... Intermediate layer 6... Electrode plate reattachment layer 7... Protrusion 8... Ti thin film

Claims (1)

[Claims] A plating mask is created on the plating plate by a multilayer resist process, and using the plating mask, a pattern is formed by electrolytic plating using the plating plate as an electrode or by electroless plating using the plate as an object to be plated. A pattern forming method, wherein the plating electrode plate is made of Cr,
A pattern forming method characterized in that the electrode plate has at least one of Fe, Mo, Nb, Ni, Ta, Ti, and alloys containing these as main components on its surface.