JPS62122237A - Semiconductor device - Google Patents

Abstract

PURPOSE:To restrain a reflow temperature at such low value as of boron phosphorus glass and to improve the reliability of an insulating film after reflow by composing an insulating film made of boron phosphorus glass containing nitrogen and using this insulating film as an interlaminar insulating film of a semiconductor device after reflow treatment. CONSTITUTION:On a lower wiring layer 5, boron phosphorus glass containing nitrogen is deposited to form an interlaminar insulating film 6 and further an upper wiring film 7 is formed on said interlaminar insulating film 6 to compose a multilayer interconnection structure. When an interlaminar insulating film 6 is formed, there is the unevenness having relatively steep steps on its surface according to the lower wiring film 5 formed into a desired pattern. By heating such a substrate at about 900 deg.C, the interlaminar film 6 is reflowed once and the unevenness is alleviated to make the surface even. The characteristics of the interlaminar insulating film after this reflow are as good as those of phosphorus glass or better than that in the all respects of resistance to crack, resistance to humidity, and resistance to chemical attach, and those have been improved exceedingly as compared with boron phosphorus glass.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a semiconductor device, and particularly to a semiconductor device having boron phosphorous glass as an insulating film.

[Background technology]

2. Description of the Related Art As semiconductor devices become more highly integrated, interconnections are becoming more multi-layered, and as a result, there is a demand for flattening of interlayer insulating films that insulate between interconnection layers. Various measures have been taken to achieve this flattening, one of which is CVD.
A reflow method has been proposed in which an insulating film formed by a method is once melted and its surface is flattened using its own surface tension. This reflow method has been used so far when silicon glass containing phosphorus, that is, phosphorus glass (PSG), is used as an insulating film, and after depositing phosphorus glass on a semiconductor substrate, it is
It is heated to melt it.

Incidentally, recently, attempts have been made to use phosphorus glass containing boron, which has a lower dust flow temperature than the above-mentioned phosphorus glass, ie, boron phosphorus glass (BPSG), as an insulating film for beam flow. According to this boron phosphorus glass, the reflow temperature can be suppressed to about 900° C., and the influence of temperature on other parts of the semiconductor device can be suppressed.

However, according to the inventor's study, the reliability of this boron phosphorus glass beam after flow, such as crack resistance,
Some concerns remain in terms of moisture resistance and chemical resistance, which may ultimately lead to a decrease in reliability of the semiconductor device and a decrease in manufacturing yield.

[Object of the invention].

SUMMARY OF THE INVENTION An object of the present invention is to provide a semiconductor device that has an insulating film with high reliability after reflow while lowering the reflow temperature, thereby improving reliability.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

In other words, by constructing an insulating film made of Poronrin glass that further contains nitrogen, and by performing reflow processing on this insulating film and constructing it as an interlayer insulating film of a semiconductor device, the reflow temperature can be made as low as that of Poronrin glass. The temperature can be controlled, and the reliability of the insulating film after reflow can be made high.

〔Example〕

The figure shows an embodiment of the present invention, in which a region 2 doped with impurities is formed on the main surface of a semiconductor substrate 1 to constitute a required element, and this element includes silicon grown on the surface of the semiconductor substrate 1. A lower wiring layer 5 of polycrystalline silicon, metal silicide, etc. is connected through the opening 4 of the oxide film 3. Then, on this lower wiring layer 5, boron phosphorus glass containing nitrogen is deposited to form an interlayer insulating film 6, and furthermore, an upper wiring film 7 is formed on this interlayer insulating film 6 to form a multilayer wiring structure. are doing.

The interlayer insulating film 6 is S i OX BY PZ Nw
It is formed by a CVD method or the like according to the following reaction formula.

SiH4+ Ox + Pth + BJb + NH
3→5xOvByPz Nw+Hz (HzO)
N and O can also be used instead of NH3.

An interlayer insulating film 6 made of this nitrogen-containing boron phosphorus glass
According to the above, when the interlayer insulating film 6 is formed, the surface has unevenness with relatively steep steps according to the lower wiring film 5 formed in the required pattern, but this is heated at approximately 900°C. By doing so, the interlayer insulating film 6 is once reflowed, the step difference is alleviated, and the surface is flattened.

The properties of the interlayer insulating film after this reflow are as follows:
It has properties equal to or better than phosphorus glass in all respects of crack resistance, moisture resistance, and chemical resistance, and is significantly improved compared to boron phosphorus glass.

Therefore, by planarizing the interlayer insulating film 6, the upper wiring film 7
It is possible to prevent step breakage, etc., and to protect the lower interconnection film 5 from corrosion and stress, thereby making it possible to obtain a highly reliable semiconductor device.

〔effect〕

(1) The insulating film of the semiconductor device is made of boron phosphorus glass containing nitrogen, and this boron phosphorus glass containing nitrogen is flattened by reflow processing, so the reflow temperature can be lower than that of phosphorus glass. The influence of temperature on each part of the semiconductor device can be suppressed.

(2) Boron phosphorus glass containing nitrogen is planarized by reflow processing, so the crack resistance, moisture resistance, and chemical resistance of the insulating film after reflow can be improved compared to boron phosphorus glass, which can improve the performance of semiconductor devices. Improved reliability can be achieved.

(3) When depositing boron phosphorus glass containing nitrogen,
It can be easily produced by simply adding a gas containing nitrogen as a reaction gas during the conventional production of borophosphorus glass.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the above embodiment, an example was shown in which the film was used as an interlayer insulating film in a wiring structure of two layers, upper and lower, but it goes without saying that it can be used as an interlayer insulating film in a wiring structure of three or more layers.

[Application field]

In the above explanation, the invention made by the present inventor was mainly applied to the interlayer insulating film of a semiconductor device, which is the background field of application, but the invention is not limited thereto. It can be applied to all insulating films.

[Brief explanation of drawings]

The figure is a sectional view of one embodiment of the present invention. ■... Semiconductor substrate, 2... Impurity layer region, 3...
silicon oxide film, 4... opening, 5... lower wiring layer,
6... Interlayer insulating film (boron phosphorus glass containing nitrogen),
7... Upper wiring layer. 1)1 Agent Patent Attorney Katsuma Ogawa 1.・.ゝ、Two.

Claims (1)

[Scope of Claims] 1. A semiconductor device characterized in that an insulating film formed on a semiconductor substrate is made of boron phosphorus glass containing nitrogen, and is subjected to reflow processing. 2. The semiconductor device according to claim 1, wherein the insulating film is an interlayer insulating film of a multilayer wiring structure. 3. The semiconductor device according to claim 2, wherein the insulating film is formed by a CVD method using a reaction gas containing nitrogen, and is subjected to a reflow treatment at approximately 900°C.