JPS62163341A - Patterning method for high melting-point metallic film - Google Patents

Abstract

PURPOSE:To use a high melting-point metal as a material for an electrode or a wiring layer, and to improve the characteristics of an integrated circuit by a method wherein two layers of an SOG film and a nitride film are laminated on a high melting-point metallic film, an opening section is formed to the nitride film through dry etching, employing a resist film as a mask, the resist film is removed through wet treatment and said SOG film and the high melting- point metallic film are each dry-etched, using the nitride film as a mask. CONSTITUTION:An element isolation region and a gate oxide film 2, etc. are shaped to an silicon substrate 1, and a high melting-point metallic film 3 consisting of Mo, W, Ti, etc. is laminated through a sputtering method. The solution of SOG (Spin On Glass) is applied and dried, and a nitride film 5 is laminated. A resist film 6 is applied. An opening section is formed to the nitride film 5 through plasma-etching, using a resist film as a mask. The resist film 6 is removed through a wet treatment method by an oxidizing strong acid. An SOG film 4 is bored through plasma-etching, employing the nitride film 5 bored through said processes as a mask, and an atmosphere is changed over to CCl4 gas and the high melting-point metallic film 3 is etched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] As the degree of integration of semiconductor devices increases and high speed performance is required, conductive materials used in wiring layers are required to have high melting point materials and low resistance characteristics. Mo that meets this requirement
, W, Ti, etc., and then removing the resist with a strong oxidizing acid in a wet process, there is a problem that the high melting point metal dissolves, and this problem was solved.

[Industrial application field]

The present invention relates to a method for patterning a refractory metal.

Aluminum and polycrystalline silicon have long been used as materials for electrodes or wiring layers in semiconductor devices.

Aluminum is difficult to use if high-temperature treatment is involved in subsequent steps after it is formed as a metal film, and polycrystalline silicon is required to have a metal material with even lower resistance when high-speed performance is required.

To solve the latter problem, high melting point metal silicide (W
Si2. MoSi2. Ti5iz, etc.) is used as a gate electrode material for MOS FETs because its resistance value is one order of magnitude lower than that of polycrystalline silicon.

Further, it is desired to use a high melting point metal having a resistance value one order of magnitude lower than that of the silicide alloy as the heavy body, but there are problems during patterning, and improvements are desired.

[Conventional technology]

Current materials such as aluminum, polycrystalline silicon, and silicide alloys have been put into practical use as metal films, but processes that use high-melting point metal materials directly for electrodes and wiring layers are still in the development stage.

[Problem that the invention seeks to solve]

The high melting point metal films are laminated by a CVD method, a spackling method, or the like.

Assume that the laminated high melting point metal film is patterned into a resist film using a photolithography method, and the high melting point metal film is etched using this as a mask.

After the etching is completed, it is necessary to peel off the resist film, but if this is done by normal wet processing, a problem arises in that the high melting point metal material dissolves in the processing solution.

Resist! I (1) As a syneresis solution, a strong oxidizing acid prepared by adding concentrated sulfuric acid to hydrogen peroxide solution is used, but this solution also reacts with high melting point metals and causes the dissolution phenomenon of high melting point metals together with the resist. wake up

In addition to the wet method, an ashing method using oxygen plasma is often used as a dry method for resist stripping, but there is a problem with the oxidation of the high-melting point metal film, and the advantages of the wet method may not be sacrificed in terms of mass production. sea bream.

After the high melting point metal film is formed, its surface is required to be covered with an insulating film, so in the present invention, the high melting point metal film is patterned using the insulating film as a mask, without removing the mask of the insulating film. We made improvements by using the method as is.

[Means for solving problems]

The above problem can be solved by laminating two layers, an SOG film and then a nitride film, on a high melting point metal film, applying a resist remover, baking, and using the resist film as a mask, dry etching to create an opening in the nitride film. form.

Next, after the resist film is removed by wet processing, the SOG film and the high melting point metal film are each dry etched using the nitride film forming the opening as a mask to pattern the high melting point metal film. This problem is solved by the patterning method of refractory metal film.

[Effect]

In the wet process for removing the resist, the high melting point metal film is covered with the SOG film or the double film of the SOG film and the nitride film, so it is not directly exposed to strong oxidizing acid.

In addition, the high melting point metal film left after patterning is
Although it is covered with a double insulating film of an SOG film and a nitride film, this can be used as it is as an insulating film for the device.

〔Example〕

An embodiment according to the present invention will be described in detail with reference to the drawings.

Assume that when a MOSFET is to be formed, an element isolation region, a gate oxide film 2, etc. have already been formed on a silicon substrate 1 by a normal method. In the drawings, parts not directly related to the present invention are omitted.

Next, a high melting point metal film 3 such as Mo, W, Ti, etc. is laminated by a spuckling method. The high melting point metal film will later become a gate electrode and a wiring layer, but since it has a significantly lower resistance value than when conventional polycrystalline silicon is used, the film can be made thinner.

Next, SOG (Spin On Glass)?
Apply the mixture at night and let it dry. The thickness of the SOG film 4 is 80
0 to 1000 people. Further, about 1000 layers of nitride film 5 are deposited by vapor phase growth. Next, a resist film 6 is applied. This is shown in FIG.

The resist film 6 is patterned to leave a gate electrode region.

Next, using the above resist film as a mask, CF4+0□
An opening is formed in the nitride film 5 by plasma etching that introduces gas. This is shown in FIG.

Next, the resist film 6 is removed by wet processing using a strong oxidizing acid. In the above treatment, the SOG film 4 or the nitride film 5 never dissolves.

Using the nitride film 5 opened in the above process as a mask, CHF3 is
The SOG film 4 is formed by plasma etching using gas.
Then, the high melting point metal film 3 is etched by switching to CCl4 gas to obtain the image shown in FIG.

Through the above process, a pattern of a high melting point metal film laminated on an SOG film and a nitride film is obtained, and the SOG film and nitride film laminated on a high melting point metal film can be used as they are.

〔Effect of the invention〕

As explained above, by applying the patterning method of the present invention, it becomes possible to use high-melting point metals as materials for electrodes or wiring layers, which greatly contributes to improving the characteristics of integrated circuits. .

[Brief explanation of drawings]

FIGS. 1 to 3 are cross-sectional views showing the patterning method for seven films of high melting point gold according to the present invention in the order of steps. In the drawings, 1 is a silicon substrate, 2 is a gate oxide film, 3 is a high melting point metal film, 4 is an SOG film, 5 is a nitride film, and 6 is a resist film.

Claims (1)

[Claims] After laminating two layers of an SOG film (4) and then a nitride film (5) on a high melting point metal film (3), a resist film (6) is applied and patterned, and then the resist film A step of forming an opening in the nitride film (5) by dry etching using the mask as a mask, and removing the resist film by wet processing. ) and the refractory metal film (3), each of which is dry etched.