JPS62263973A - Thin metallic film and its production - Google Patents

Abstract

PURPOSE:To simply and easily obtain a thin metallic film in which the metal having excellent dimensional accuracy is made to remain by forming a thin org. metallic film on a substrate, and radiating electric charge particle beams thereto to decompose the org. metal. CONSTITUTION:An SiN film 2 of a holding substrate is formed on an Si wafer 1 and the thin org. metallic film 4 is formed thereon by spin-coating the org. metal thereon. The charge particle beams are radiated thereto in a vacuum at the acceleration voltage necessary for the thickness of the thin film 4, and the thin org. metallic film 4 is changed to the thin metallic film 4 down to the boundary with the SiN film 2. The thin org. metallic film 4 in the non- radiated part is then dissolved away by a solvent. The thin metallic film 5 formed with the fine wire pattern of the metal is thereby obtd. The above- mentioned metal is preferably Au or Pt and the charge particles are preferably ions. This method is adequate for a field such as X-ray lithography for forming the fine pattern.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention is particularly applicable to fields such as X-ray lithography for forming fine patterns, and is particularly suited to the field of X-ray lithography produced with high precision.
Concerning line masks and their production and modification methods.

(Prior Art) As semiconductor devices become smaller, there is an increasing possibility that X-ray lithography will be used instead of optical lithography in their manufacturing process. This is because the wavelength of the light used for miniaturization is limited, and soft X-rays with wavelengths several orders of magnitude smaller than visible light are attracting attention. Lenses cannot be used in such wavelength ranges. In optical lithography, a mask having a pattern five or ten times larger than the pattern on the semiconductor is used, and since this can be reduced using a lens, the accuracy of the mask pattern may be moderate.

However, in soft X-ray phosphorography, 5 times, 10 times
A double mask cannot be used, so a 1:1 equal size mask is used.

Therefore, the equalization mask pattern is required to have an accuracy of - several times the minimum line width.

By the way, the general structure and manufacturing method of masks used in soft X-ray lithography are as follows. An inorganic thin film made of a low atomic number element is deposited on the surface of a silicon wafer. This will be the substrate that holds the mask pattern of the X-ray absorber, which will be described later, and is made of BN, Si, and
, SIO Yu et al. Polyimide films and multilayer films thereof may also be used instead of inorganic films. A pattern of X-ray absorbers is then formed on this holding film. Au is a chemically stable material with a large atomic number for the absorber.

Pt, W, Ta, etc. are used. Among them, Au is the most widely used. These absorbent patterns are manufactured using two different methods. In the first method, Au
50=100 of Cr or Ti etc. to improve adhesion with
Manual vapor deposition, then 50-10 Au as a plating base
Deposit 0 shaku. A resist is applied, and the resist is microfabricated by electron beam exposure to form an opening up to the Aug film.

Next, ALJ plating is performed using this Aug film as a cathode.

Au is plated only on the openings of the resist. 0.5
After growing a plating layer to a thickness of about μm, the resist is removed, and the thin AU/(Cr, Ti) films under Regime 1 are removed with dilute aqua regia or the like. Finally, only the central portion of the 3i wafer under the holding thin film is edged from the back surface, leaving only the holding thin film. Due to this.

An X-ray mask having an Au pattern formed on a thin film transparent to visible light and soft X-rays is obtained. Next, in the second pattern formation V, ALJ,
The absorber pattern is formed by depositing PT, D, W, etc. on one surface to the thickness required for the absorber, and then etching it. If the absorber is AIJ, 50-100
Deposit Cr or Ti film.

On top of this, AU is deposited to a thickness of about 0.5 μm. Next, set Ta to 0
．． Electron beam evaporation is also performed to a thickness of 1-0.2 μm. After applying a resist and forming a pattern by electron beam exposure, RI is performed using a gas such as CBrF3 using this resist as a mask.
Edge [E] a and form a pattern on Ta 1 then T
A pattern is formed on the AU by Ar ion etching using a as a mask. After etching, the central pattern portion 3i is etched from the back side to complete the mask.

The absorber of the X-ray mask produced in this way is not perfect over the entire area and has defects.

For example, in the case of an Au pattern made by plating, if some resist openings are too large or there are extra pinholes, the Au
Increased size or unnecessary ALJ attachment. For such defects, redundant absorption patterns can be removed using the sputtering function of a focused ion beam. On the other hand, it is not easy to correct missing parts of a pattern. Similarly, using a focused ion beam, the high-vacuum ion beam chamber and sample chamber are separated, a small hole is provided for the ion beam to pass through, and the ion beam is introduced into the sample chamber. The sample chamber contains Ta (QC!2H,>, for aqua deposition).

For W deposition, a reduced pressure gas of WF6 is flowed, the beam is aligned with the location to be deposited, and when irradiated, gas molecules are adsorbed and decomposed by ions, and Ta and W are deposited. However, in this method, the gas used flows into the high vacuum chamber even though the holes are small. or.

Modification using ALJ or Pt, which is chemically stable, is impossible because there is no molecular compound that is a gas at room temperature.

(Problems to be Solved by the Invention) To summarize the above, in conventional X-ray masks and their manufacturing methods, the resist process using electron beam exposure, which has problems in microfabrication due to proximity effects, is replaced by plating or RI.
It is complex to combine with E for missing defect correction of absorption pattern.

-5=It can be said that there was no direct deposition method for Au and pt. The purpose of the present invention is to obtain a direct absorber pattern without requiring the above-mentioned combinations in mask production, and to achieve high-precision The aim is to provide line masks, etc.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, T is referred to as bric]ht gold. A thin film of a compound of terpenes, sulfur derivatives, and gold (or platinum) salt (hereinafter referred to as organic gold or organic platinum) is formed on a substrate, and decomposed by ion beam irradiation in a vacuum to evaporate the nonmetallic components.

A gold (or platinum) film is formed on the substrate by leaving only the gold (or platinum) and removing the unirradiated thin film. A fine pattern of gold or the like can be obtained by passing a parallel ion beam through a mask to pattern the cross section and irradiating it, or by performing drawing irradiation using a focused ion beam obtained from a so-called liquid metal ion source. To repair missing defects in X-ray mask absorbers, after coating the X-ray mask with the organic gold thin film described above, only the missing parts are irradiated with a focused ion beam, depositing gold, etc. to repair them, and later removing the excess. Dissolve and remove the thin film.

(Function) A compound of terpenes, sulfur attractants, and gold (or platinum) salt, ie, brrght gold, is applied to ceramics, etc., and is bound into a thin film.By heating at 700-800°C, it is possible to remove substances other than gold (platinum). It is known that when light elements evaporate, a thin film of gold (platinum) remains, but this organic gold (platinum)
We found that a similar effect can be obtained by irradiating a thin film with an ion beam in a vacuum. Since the distance 1 that the ion beam reaches into the thin film is determined by its acceleration voltage, the ion beam is irradiated with the acceleration voltage necessary for the thickness of the N film.

The organic thin film is changed to a gold (platinum) thin film up to the interface with the substrate, and even when the non-irradiated organic thin film is removed with a solvent, the metal film can be left behind.

(Example) (I) A 1 μm thick SiN film with low tensile stress was formed on a 2-inch diameter 3i wafer, and on top of this was diluted with a solvent.
Right gold is spin coated like a resist used in lithography and dried. To accelerate drying, it may be kept in nitrogen gas for about 80'0.20 minutes.

A uniform organic gold thin film about 0.5 μm thick was obtained. This was placed in a focused ion beam device under a vacuum of lx10-'Pa.

A Ga ion beam was irradiated with an accelerating voltage of 180 kV. Beam diameter is 0.5μm, beam current is 8X10”△
Met. Line dose is 1.5XIC5'1ons/cm
I scanned the beam so that it hit the target. As a result of dissolving and removing the unglazed a thin film with a solvent such as toluene or trichlorethylene, it was found that a fine gold line pattern with a width of 0.5 μm and a height of 0.27 μm was formed on the SiN. A circle with a diameter of 20 mm was removed from the center of the Si wafer by etching, used as an X-ray mask, and the gold pattern side was coated with 20 .mu.ml of Regime 1 to 2, which was applied to another 3i wafer.

Irradiates soft X-rays from the pattern side and exposes the resist.

As a result of development, a resist pattern of 0.5 μm was obtained. There was no proximity effect during electron beam exposure for both the thin line pattern and the large area pattern.

(2) When a gold mask pattern formed by plating on a SiN film on the same <Si wafer was inspected using an electron beam, it was found that linear portions were missing, which was thought to be due to dust in the plating solution. 0.4μm thick.

The gold wire with a width of 0.5 μm was missing over a length of 1.5 μm. An organic gold thin film was applied onto a 0.75 μm mask, and a focused ion beam was irradiated onto the defective area based on the data from the inspection. B “beam accelerating voltage of 150kV, 8X10
It was irradiated with a current of A.

Tj-mu diameter is 0.25μm, F-zu is 3X10”1on
Inspection after removing the organic film showed that the defective portion was completely filled with gold wire.

(3) On the same <Si wafer, an organic platinum thin film of 0.8 μm was spin-coated on a composite film of a BN film and an organic polyimide film. A parallel He+ beam was pattern-irradiated onto the organic platinum film through an ion beam channeling mask formed on the Si thin film. The acceleration voltage is 70kV and 150kV,
Illuminate 1-10 m L of 2X10 /cm'L at each accelerating voltage. Dissolve and remove the non-irradiated area with a solvent to give approximately 0.4
A Pt pattern with a thickness of 5 μm was obtained.

[Effects of the Invention 1 As described above, the present invention is a simple method for manufacturing an X-ray mask that does not require a resist process using electron beam exposure, and provides excellent dimensional accuracy. This can be said to be an excellent method for correcting missing defects.

Although gold (or platinum) may contain some organic film constituent substances at the ionobeam irradiated area, heat treatment at 700-800° C. or the like may be performed after removing the non-irradiated area. AL
J, pttj; t: SiN, SiO.

Since the adhesion between Cr and Au is weak, it is common practice to coat Cr or Au with plating before applying an organic gold (platinum) film.
(Pt) is deposited by 40 to 100 people each, and after forming a gold (platinum) pattern according to the present invention, unnecessary portions of the metal thin film may be removed by a slight etching process. In this text, the formation of an absorber pattern for an X-ray mask has been described, but gold and platinum are good conductors even when the metal is 10-, and minute wiring can be formed according to the present invention. Furthermore, for example, gold can be used as an adhesive material because it can easily form a eutectic alloy with other elements, so the present invention can be used to form a gold thin film for adhesives.

[Brief explanation of drawings]

FIG. 1a is a diagram showing the production of an X-ray mask according to the present invention, b is a diagram showing the configuration of the X-ray mask, FIG. FIG. 1...Silicon wafer. 2... Holding substrate SiN. 3... Focused ion beam. 4...Organic gold (platinum) thin film. 5... Gold (platinum) thin film decomposed by ion beam irradiation. 6... Gold (platinum) thin film. 7...High vacuum side. 8...Small hole. 9...Low pressure gas such as WF6. 10...King of ion beam irradiation decomposition a (W) thin film. Diagram 1 leading to Omura

Claims (1)

[Claims] (I) A metal thin film formed on a substrate, in which the organic metal thin film is irradiated with an accelerated charged particle beam to decompose the organic metal, leaving the metal remaining, and a method for producing the same. (II) The metal thin film and method for producing the same according to item (I), wherein the metal is Au or Pt. (III) The metal thin film and method for producing the same according to item (I), wherein the charged particles are ions.