JPS59138338A - Semiconductor device - Google Patents

Abstract

PURPOSE:To give the resistance to steam whereas keeping the gettering effect of impurities by constructing a phosphorus glass layer as the two-layer construction, that is a lower layer of high phosphorus concentration and an upper layer of low phosphorus concentration. CONSTITUTION:In a polycrystalline Si gate FET, phosphorus glass layers 71 and 72 are deposited on a polycrystalline Si gate region 5 through an oxide film and on a field oxide film 6. Among these layers, the layer 71 has the phosphorus concentration of 8X10<20>cm<-3> and the layer 72 has that of 1-8X10<20>cm<-3>. By this constitution, the layer 71 sucks out impurities present on the surface of an Si substrate 1 and performs gettering. Meanwhile, the layer 72, whose gettering effect is weaker than that of the layer 71, comprises the phosphorus concentration showing enough gettering effect for the impurities from external atmosphere as well as the resistance to steam.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device including a film mainly composed of silicon oxide containing υ as a passivation film.

As an example of using a compound of a semiconductor material as a passivation film of a semiconductor device, a silicon nitride film or a silicon oxide film containing υ (hereinafter referred to as phosphorus glass) in a silicon semiconductor device is known. Although silicon nitride has better properties than silicon oxide in blocking the permeation of impurity ions, it causes changes in the characteristics of semiconductor devices during silicon nitride film formation, resulting in lower yields and higher device manufacturing costs. There is a problem. On the other hand, phosphor glass uses the gettering effect of phosphorus to remove impurities from the semiconductor surface, but if the concentration of phosphorus is increased to ensure a sufficient gettering effect, the water absorption of the phosphor glass increases. However, it has the drawback that its resistance to water vapor in the external ambient air is weakened, and it also becomes more susceptible to etching, reducing the precision of microfabrication of the passivation film due to side etching.

The present invention eliminates the above drawbacks and provides a semiconductor device having a phosphor glass passivation film that maintains the gettering effect of impurities, has resistance to water vapor in the external surrounding air, and is sufficiently capable of microfabrication. The purpose is to

The purpose of this is to use a phosphor glass layer as a passivation film, which includes a layer containing more than 8X1020 QI7B provided on the side closer to the semiconductor element, and a layer containing more than 1 to 8X10 QI7B provided on the side farther from the semiconductor element. This is achieved by comprising layers containing:

Embodiments of the present invention will be described below with reference to the drawings. In the polysilicon gate field effect transistor shown in FIG. is formed.

A glass layer 71 with a density of 1.5 x 10"rn-3 is formed on the polysilicon gate region 5 via an oxide film and on the field oxide film 6 as a surface protection film by chemical vapor deposition. (CVD method), then a phosphor glass layer 72 with a phosphor concentration of 7×10 crn is deposited on the upper surface by the same CVD method.Each phosphor glass layer 71°7
The thickness of 2 is 80001 mm. Next, gate oxide film 4, field oxide film 6, and thin glass layer 71°72
After opening the window using photoetching method, A/wiring 8t-
Then, a silicon nitride film 9 is coated as a final passivation film. With this configuration, the lower thin glass layer 71 sucks out impurities on the surface of the silicon substrate 10 and performs gettering. Although the upper thin glass layer 72 has a lower gettering effect than the lower layer 71, it has a thin concentration that exhibits a sufficient gettering effect against impurities from the external ambient air, and also has resistance to water vapor. . Furthermore, when etching the window, the corrosion resistance of the upper shingle glass layer 72 is sufficient, and there is little side etching, allowing for fine processing. Furthermore, since the entire surface is covered with the final passivation film 9, the protective effect is even more complete. Note that this silicon nitride film 9
Since they are provided on the thin glass layers 71, 72, they do not change the characteristics of the device.

However, as shown in FIG. 2, in which parts common to those in FIG.
It is also possible to apply 72 as a final passivation film after wiring of the electrode film 8.

As described above, according to the present invention, a thin glass layer as a passivation film of a semiconductor device is made of two layers: a lower layer with a high phosphor concentration, which has a large gettering effect, and an upper layer with a low phosphor concentration, which has a high resistance to water vapor. Because of the layered structure, it has a sufficient gettering effect for impurities that affect the surface state of the semiconductor, and can also maintain its function as a passivation film that can block the effects of water vapor or impurities in the external atmosphere. Therefore, the reliability of the semiconductor device can be improved.

The present invention is not limited to the polysilicon gate field effect transistor mentioned in the embodiment, but can also be applied to individual elements such as bipolar transistors, diode single resistors, etc. Furthermore, since the passivation film has good microfabrication properties, it can be constructed from these elements. The effects that can be obtained on all semiconductor devices, such as the possibility of higher integration of integrated circuits, are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the invention, and FIG. 2 is a sectional view showing another embodiment of the invention. 1... Silicon substrate, 4... Gate oxide film, 5...
・Polysilicon gate, 6...Field oxide film, 7
1...High phosphorus concentration phosphor glass layer, 72...Low phosphor concentration phosphor glass layer, 8...Ke wiring. 2/ Concave rz mouth

Claims (1)

[Claims] 1) A thin glass layer as a passivation film is provided on the side closer to the semiconductor body, and a layer containing more than 8×10 an is provided on the side far from the semiconductor body.
A semiconductor device comprising a layer containing υ of ˜8×1020ryrrb-3.