JPS60224229A - Semiconductor device - Google Patents

Abstract

PURPOSE:To stop decreasing of moisture resistance due to the influence of phosphorus to the first wiring layer without altering the present process by forming the first layer wiring of wirings through an inorganic insulating film containing no phosphorus on an inorganic insulating film which contains phosphorus oxide glass layer on the surface. CONSTITUTION:A glass (PSG) film 7 which contains high density phosphorus oxide is formed on the surface of a silicon oxide 2 for coating the surface of a semiconductor element formed on the other portion of the surface of a substrate 1. An inorganic insulating film 8 which does not contains phosphorus, formed on the film 7 is made, for example, of glass (SOG) by coating and silicon oxide by CVD not doped with nitride or phosphorus due to plasma discharging. The first layer wirings made of aluminum are formed as an electrode contacted with low resistance with the element, and partly extended on the film 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a semiconductor device, and more particularly to a technology for improving moisture resistance of a semiconductor device having an aluminum multilayer wiring structure using a polyimide resin for a passivation film.

[Background technology]

2. Description of the Related Art As the number of elements per chip increases in semiconductor devices such as ICs and LSIs, aluminum wiring for connecting elements is now formed into a multilayer structure of two or more layers.

In the present inventor, a semiconductor element such as a transistor covered with a silicon oxide film 2 is formed on the surface of a silicon semiconductor substrate 10 as shown in FIG. A wiring 3 is formed, the first layer wiring 3 is covered with an interlayer film 4 made of polyimide resin, a second layer aluminum wiring 5 is formed on the interlayer film 4, and a protective layer made of polyimide resin is formed on the interlayer film 4. A two-layer wiring structure in which a film 6 is formed is adopted.

Polyimide resin can be formed on top of the wiring to ensure surface flatness, and it has high heat resistance, so it is often used as a glabellar membrane or protective film, but aluminum Wiring corrosion is a problem.

Therefore, the present inventor has devised a method for preventing aluminum wiring corrosion due to water intrusion from above by using aluminum containing highly moisture-resistant silicon as the second layer (upper layer) aluminum wiring material in a two-layer wiring structure. was proposed (Japanese Patent Application Laid-Open No. 57-154857).

However, in the first layer (lower layer) of the aluminum wiring 3, when aluminum containing silicon is used, there is a problem in that silicon residue is generated, and when a part of the transistor is used as a barrier, the barrier hydride has a low value. Because pure aluminum is used to maintain the temperature of the chip, the problem of wiring corrosion due to water intrusion from the sides (around the chip) remains unresolved.

The inventor of the present invention investigated the cause of such defects in the first layer aluminum wiring, and found that corrosion is particularly likely to occur in the first layer aluminum wiring #I3 around the chip, and that the silicon on which this first layer wiring is formed It was found that there is a relationship with the phosphorus concentration of the 7-osilicate glass (PSG) film 7 on the surface of the oxide film.

In current semiconductor manufacturing that has a two-layer wiring structure with polyimide resin as an interlayer film, the base of the first layer aluminum wiring is PSGg with a phosphorus concentration of 4 mol, which is npn)? Sift is silicon oxide (Sift) containing about 12 mo1 of phosphorous glass that is generated on the device surface after the emitter diffusion of the resistor, and the pure aluminum currently used for the first layer wiring is easily affected by the underlying phosphorus. It was found that this resulted in a decrease in moisture resistance.

On the other hand, the moisture resistance of the second layer wiring is improved by using silicon-containing aluminum, and therefore the first layer
It has been found that the life span of an IC can be determined by the layered aluminum wiring.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and it is an object of the present invention to provide a semiconductor device technology that can improve the moisture resistance of a first layer aluminum wiring covered with a polyimide resin.

[Summary of the invention]

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

That is, a plurality of semiconductor elements are formed on one main surface of a semiconductor substrate, the semiconductor elements are covered with an inorganic insulating film (phosphorus glass) containing a phosphorous oxide glass layer on the surface, and one or more layers are formed on the inorganic insulating film. Multiple layers of aluminum wiring are formed,
In a semiconductor device in which the wiring is covered with an organic insulating film such as polyimide resin, an inorganic insulating film that does not contain phosphorus is placed on the surface of the inorganic insulating film that includes a phosphorus oxide glass layer. By forming the first layer (lower layer) of the wiring, it is possible to prevent the deterioration of moisture resistance due to the influence of phosphorus on the first layer wiring and improve the moisture resistance without changing the current process. The purpose of the invention can be achieved.

〔Example〕

FIG. 2 shows one embodiment of the present invention, and is a longitudinal sectional view of a semiconductor device having a two-layer wiring structure using polyimide resin as an interlayer film.

Reference numeral 1 denotes a silicon semiconductor substrate, and although not shown, semiconductor elements such as busy transistors are formed on other parts of the surface of the substrate 10 . 2 is a silicon oxide (Sin) film covering the surface of the semiconductor element. This silicon oxide 2
A glass (PSG) film 7 containing a high concentration of phosphorous oxide is formed on the surface of the substrate. Reference numeral 8 denotes an inorganic insulating film 8 containing no phosphorus, such as glass (SOG) by coating, nitride (silicon nitride) by plasma discharge, or silicon oxide (Sift) by CVD (vapor phase chemical deposition) K, which is not doped with phosphorus at all. ).

Reference numeral 6 denotes a first layer wiring made of aluminum (mainly pure aluminum), which is formed as an electrode that makes low resistance contact with the semiconductor element, and a portion thereof extends over the inorganic insulating film 8 .

4 is an interlayer insulating film made of polyimide resin.

Reference numeral 5 denotes a second layer wiring made of aluminum or silicon-containing aluminum, and a portion thereof is connected to the second layer wiring through a through hole in the interlayer film 4.

6 is protection made of polyimide resin (for protection)
It is a membrane.

Phosphate glass 7 on the surface of silicon oxide film 2 on the substrate
It is thought that the phosphorus accelerates the corrosion of the aluminum grain boundaries of the first layer wiring formed under the upper pressure, but as in the present invention, plasma containing no phosphorus is applied to the phosphorus oxide glass 7 By covering with an inorganic insulating film such as nitride that does not contain any phosphorus, the influence of the underlying phosphorus can be prevented on the aluminum wiring #3 formed thereon, and the moisture resistance can be improved.

Figure 3 shows another embodiment of the present invention, and is a partial step sectional view of the manufacturing process of an IC (semiconductor integrated circuit) having an NPN (npn) transistor on one main surface of a semiconductor substrate. be. Each process will be explained below.

(1) 1 normal bibo as shown in figure 3 pressure water? In accordance with the IC process, an n-type silicon layer 11 is epitaxially grown on a p-type silicon substrate 9 with an n+-type buried layer 10 buried therein, and boron (B) is grown using the surface oxide film 12 as a mask.
) A p-type isolation section 13 is formed by ion implantation and diffusion.

(2) A part of the surface oxide film 12 is opened by photoresist treatment, and one n.
In the "" type silicon region 11, as shown in FIG.
)? A p layer region 14 which will serve as a transistor pace and an n+ type region 15 which will serve as a collector contact are formed. Through these steps, the oxide film in the peripheral field area of the device is reduced to 12,000 yen.
The thickness will be about A.

After that, as shown in the same figure, the oxide film on the emitter and collector contacts is removed, and a glass (PSG) layer 16 containing highly concentrated phosphorus oxide is deposited on the entire surface by heating in an oxygen atmosphere containing phosphorus. By diffusing phosphorus into the semiconductor through the window opening, the emitter n+
A mold area 17 is obtained. PSG layer on the surface of the oxide film (thickness 300
A) 16 is left as is to prevent contamination of the pn junction by metal impurities.

+3] Silicon oxide which is not doped with phosphorus by CVD (vapor phase chemical deposition method) is heated to 5KPS in Figure 5.
G is deposited on the entire surface of the substrate, and non-sulfur-doped Sin
, the film 18 is formed to a thickness of about xooo1. After this, contact photoetching is performed to open the electrode extraction portions in each region. In this case, the non-doped SiOg film other than the contact portion may be left so as to surround at least the peripheral portion of the aluminum wiring, and other unnecessary portions may be removed at any time.

141 Aluminum is deposited (or sputtered) on the entire surface and patterned and etched to form aluminum electrodes 19 in contact with each semiconductor region as shown in FIG. A portion of this aluminum electrode extends over the oxide film and is used as an aluminum wiring.

(5) Apply polyimide resin to the entire surface to form a protective insulating film 20 having a final thickness of 1.75 to 0 μm after baking. This polyimide resin film is made by applying a prepolymer solution of polyimide resin or a half-form compound solution (for example, a solution of N-thimethyl-2-pyrrolidone or .N.N-dimethyl-acetamide) using a spinner (once or twice). ), the solvent component is evaporated, and further 200 to 300
The film is polymerized and cured by baking (heat treatment) at .degree. C. to form the above-mentioned film.

In this embodiment, since the non-doped CVD SiO2 film can be easily formed using the current Pivot 2 IC process technology, the influence of phosphorus can be prevented and the moisture resistance is improved.

Although the invention made by the present inventors has been specifically explained based on examples, the present invention is not limited to the above-mentioned implementation pressure (and various changes can be made without departing from the gist thereof).

For example, an inorganic insulating film that does not contain phosphorus to be formed on the soil of the PSG layer can be formed by coating liquid silica-based glass using a spin coating method and baking it to form a glass film, or by coating silicon in a plasma discharge electric field. By using a method of depositing 8 iN (silicon nitride) obtained by reacting nitrogen, the influence of pressure phosphorus can be similarly prevented and the moisture resistance can be improved.

〔effect〕

According to the present invention, as a result of conducting a moisture resistance test of an aluminum Elam wiring in a semiconductor snowboard in which an inorganic insulating film not doped with phosphorus was formed to cover a glass layer containing phosphorus oxide on a surface oxide film, the moisture resistance was confirmed. It was found that the l'&w was improved to the same level as corrosion-resistant electrode materials such as silicon-containing aluminum.

Semiconductor devices using polyimide resin have a special IC two-layer wiring structure, and corrosion resistance can be ensured by using silicon-containing aluminum for the second layer wiring, but the first layer wiring can be used for elements! It is difficult to use silicon-containing aluminum because it is easily affected by characteristics (for example, characteristics caused by silicon etching due to "opening" of a transistor with a Shirotto barrier diode or "opening" between the aluminum wiring and the element contact part). According to the present invention, such problems can be solved by a simpler method than the process of forming the first inorganic insulating film.

[Application field]

The present invention can be applied to all semiconductor devices having a two-layer aluminum wiring structure or a single-layer aluminum wiring structure using a polyimide resin as an interlayer film or a protective film.

[Brief explanation of the drawing]

FIG. 1 is a partial longitudinal sectional view showing an example of a semiconductor device having a two-layer wiring structure. FIG. 2 shows an embodiment of the present invention, and is a partial vertical sectional view of a semiconductor device having a two-layer wiring structure. FIG. 3 shows another embodiment of the present invention, and is a cross-sectional view of a manufacturing process of a semiconductor device having a single-layer wiring structure (NPN)9 transistor. Fig. 4 is a process cross-sectional view showing emitter diffusion, Fig. 5 is a cross-sectional view showing non-doped insulating film formation, Fig. 6 is a cross-sectional view showing electrode formation, and Fig. 7 is a process cross-sectional view showing emitter diffusion. FIG. 3 is a cross-sectional view showing a state in which a film is applied. DESCRIPTION OF SYMBOLS 1... Silicon semiconductor base, 2... Surface oxide film, 3
... First layer aluminum wiring (electrode), 4... Interlayer membrane made of polyimide resin, 5... Second layer aluminum wiring, 6... Peritoneal membrane made of polyimide resin, 7
...Glass containing phosphorous oxide, 8...CVD*Si
O. Film, 9...p-type silicon substrate, 10...n+ type buried layer, 11...n-type silicon layer (epitaxial layer), 12...surface oxide film, 13...p type Isolation eye section, 14...Base pm! Region, i5...Collector contact n+ type region, 16...P2O layer, 1
7...Emitter n+ type region, 18...Tundob 5i
Oz film, 19...aluminum wiring, 20...polyimide film. Figure 1 Figure 2 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] 1. A plurality of semiconductor elements are formed on the entire surface of a semiconductor substrate, the semiconductor element is covered with an inorganic insulating film containing a phosphorous oxide glass layer on the surface, and a Vc1 layer or a Vc1 layer is formed on the inorganic insulating film. A semiconductor device having multiple layers of wiring mainly composed of aluminum and covered with an organic insulating film on the wiring or between the wirings, the inorganic insulation including a phosphorous oxide glass layer on the surface. Through the upper pressure of the film, an inorganic insulating film that does not contain phosphorus,
A semiconductor device comprising a first layer (lower layer) of the wirings described above. 2. The semiconductor device according to claim 1, wherein the organic insulating film is made of polyimide resin.