JPS62113421A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To allow electrodes to remain stable in their electric characteristics during a high-temperature treatment by a method wherein a high-melting metal film is formed on an insulating film and a contact hole provided therein, a high-melting metal nitride film is formed on the high-melting metal film, heat treatment is accomplished in an oxygen atmosphere for the formation of a thin oxide film on the metal nitride film, and then wiring metal is provided on the thin oxide film. CONSTITUTION:A prescribed impurity is diffused into a P-type silicon substrate 1 for the formation of an N<+> type diffusion layer 2, and then a silicon oxide film 3 is formed by selectively removing the silicon oxide film 3 from the diffusion layer 2 for the formation of a contact hole in the silicon oxide film 3. Next, titanium is deposited on the entire surface for the formation of a titanium film 4, whereon a titanium nitride film 5 is deposited. The substrate 1 is then subjected to heating in an oxygen atmosphere for the formation of an titanium oxide film 6 on the surface of the titanium nitride film 5. Next, an aluminum wiring film 7 is formed to cover the entirely of the titanium oxide film 6. A wiring pattern is formed when the aluminum wiring film 7, oxide film 6, titanium nitride film 5, and then titanium film 4 are subjected in succession to etching.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming a wiring layer.

[Technical background of the invention and its problems]

In general, wiring metals formed on semiconductor substrates include:
Aluminum or aluminum-silicon alloys are used. However, when aluminum is used as a wiring metal, 1. Due to the temperature rise associated with heat treatment in the normal device manufacturing process, in transistors or ICs with shallow impurity diffusion layers, aluminum may react with the substrate silicon, causing aluminum to invade the substrate silicon. There is a risk that the junction formed by this shallow diffusion layer will be destroyed.

In addition, when aluminum-silicon is used as a wiring metal, excess silicon contained in aluminum exceeding the solid solubility limit precipitates in the wiring and contact holes due to temperature rise and cooling during the element manufacturing process. . Precipitated silicon has high resistance, especially for N-type contact holes.
Since the precipitated silicon is P-type doped with aluminum and nium, it has extremely high resistance.

As a means to solve the above problems, conventionally, in order to suppress the reaction between aluminum and the substrate silicon, high melting point metals such as titanium, molybdenum, tungsten, or their nitrides or silicides are used between the aluminum wiring layer and the substrate silicon. It is practiced to provide a material layer.

However, even with this method, it is not possible to sufficiently suppress the reaction between the wiring material aluminum and the high melting point metal and substrate silicon due to heat treatment in the element manufacturing process.
There were still problems with the stability of electrode properties.

[Purpose of the invention]

The present invention improves the drawbacks of the prior art as described above.
An object of the present invention is to provide a semiconductor device having a stable and low-resistance contact electrode.

[Summary of the invention]

In order to achieve the above object, according to the method of manufacturing a semiconductor device of the present invention, after forming a high melting point metal film on the insulating film and the surface of the contact opening, and further forming a nitride high melting point metal layer on top of the high melting point metal film, Atmosphere (1~3X10'''”Torr
) to thinly oxidize the surface of the metal nitride in a chamber (400° C.), and then a wiring metal is formed on the oxide film to form a wiring path.

[Effects of the Invention] According to the present invention, it is possible to realize a highly reliable electrode that can suppress the reaction between aluminum, high melting point metal nitride, and substrate silicon, and maintain stable electrode characteristics even during high-temperature heat treatment.

[Embodiments of the invention]

Hereinafter, details of the present invention will be explained according to one embodiment. 1st
4 to 4 are process cross-sectional views showing an embodiment of a method for manufacturing a semiconductor device according to the present invention.

First, P is applied to a P-type silicon substrate 1 by a conventional method.

A predetermined impurity such as As is diffused to form an n-type diffusion layer 2. Next, a silicon oxide film 3 is provided on the surface of the silicon substrate 1, and the silicon oxide film 3 on the diffusion layer 2 is further selected by a photoresist method. A contact hole is provided in the silicon oxide film 3 by removing the contact hole.

(FIG. 1) Next, titanium is deposited on the entire surface by sputtering using an ordinary sputtering device to form a titanium film 4 of 100 to 500 layers. Thereafter, a titanium nitride film 5 (1,000 to 2,000 layers) is successively deposited on the titanium film 4 by one-reactive sputtering.

(FIG. 2) Next, this substrate 1 is heat-treated at 400° C. in an oxygen atmosphere (1 to 3 mTorr) to form a Ti oxide film 6 (20 to 3 mTorr) on the surface of the titanium nitride film 5. 50
people). (FIG. 3) Next, an aluminum wiring metal film 7 having a thickness of 8,000 wafers is formed on the entire surface of this oxide film by a conventional sputtering method. Thereafter, the aluminum wiring metal film 7 and the underlying oxide film 6° titanium nitride film 5. The titanium film 4 is continuously etched to form a wiring pattern. (Fig. 4) In this way, a titanium layer 4. Titanium nitride layer 5. Oxide layer 6. By creating a laminated structure of the aluminum wiring metal layer 7 and inserting a very thin Ti oxide film layer 6 between the titanium nitride layer 5 and the aluminum wiring metal layer, the reaction between titanium nitride and aluminum is suppressed. Furthermore, the reaction between aluminum and the silicon substrate was suppressed. Furthermore, it has become possible to use pure aluminum as the wiring metal as in this embodiment. In that case, the wiring will have a lower resistance than when an aluminum-silicon alloy is used for the wiring.

Note that the high melting point metal used in the examples is not limited to titanium, and similar effects can be expected even if molybdenum, tungsten, tantalum, etc. are used. In addition, in the embodiment, n
Although the case of a diffusion layer is taken as an example, it can also be applied to the case of a p layer. Further, the wiring layer is not limited to aluminum, but may also be an aluminum-silicon alloy. Further, the substrate 1 is not limited to silicon, but may be made of GaAs, or may have an SO8 structure.

In addition, various modifications can be made without departing from the spirit of the present invention.

As explained above, according to the present invention, the reaction between the substrate and the wiring metal is suppressed, and wiring with low resistance can be realized.

[Brief explanation of drawings]

FIGS. 1, 2, 3, and 4 are sectional views showing manufacturing steps of an embodiment of the present invention. In the figure, 1... silicon semiconductor substrate, 2... impurity diffusion layer,
3... Silicon dioxide film, 4... Titanium film, 5...
・Titanium nitride film, 6... Oxidized high melting point metal film,
7...Aluminum wiring metal film. Agent Patent Attorney Noriyuki Chika Yudo Kikuo Takehana

Claims (1)

[Claims] In a method for manufacturing a semiconductor device in which an insulating film is formed on the surface of a semiconductor substrate and a wiring layer contacts a diffusion layer in an opening of the semiconductor device, after forming an opening in the insulating film, a high melting point metal film and then a nitride high melting point metal film are formed. A semiconductor characterized by comprising a step of adhering it, a step of oxidizing its surface to form an oxidized high-melting point metal film, and a step of forming an aluminum-based wiring layer on the oxidized high-melting point metal film. Method of manufacturing the device.