JPS6139745B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and in particular a method for manufacturing a semiconductor device using a silicon nitride film for surface stabilization, and a method for manufacturing a semiconductor device having a shallow junction with a fine pattern. It is related to.

Semiconductor devices with conventional fine patterns and shallow junctions,
For example, one method for forming a silicon nitride film to stabilize the surface of a washed emitter structure transistor for high frequency use is as follows.

FIG. 1 is a cross-sectional view showing the main steps in manufacturing an example of a conventional semiconductor device.

A P-type base region 12 is provided on an N-type silicon substrate 11, and a silicon oxide film 13 and a silicon nitride film 14 are sequentially deposited on the surface of the substrate 11 (FIG. 1a).

Next, using the photoresist film 15 as a mask, the silicon nitride film 14 and the silicon oxide film 13 are sequentially and selectively removed to form an opening reaching the base region 12 (FIG. 1b).

Next, after removing the photoresist film, phosphorus is diffused through the opening to form an N region 16 in the P type base region 12 to serve as an emitter region (FIG. 1c).

Next, a photoresist film 15' is selectively formed, and the photoresist film 15' is used as a mask.
The silicon nitride film 14 and the silicon oxide film 13 are sequentially removed to form an opening that reaches the base region 12 (FIG. 1d).

Next, the photoresistor film 15' is removed, and metal electrodes 17, 17', 17'' are formed on the base region 12 and the emitter region 16 using a metal capable of ohmic connection using a conventional method (first Figure e).

Although the above is a conventional manufacturing method, this manufacturing method has the following drawbacks.

In the step of forming the washed emitter structure (Fig. 1c), the base region 1 is
After providing the N-type region, ie the emitter region 16, in the substrate 2, the phosphorus glass layer formed on the substrate surface must be removed in order to enable an ohmic connection with the metal electrode. However, since the silicon oxide film and the silicon nitride film have different conversion rates to phosphorous glass and the silicon oxide film is larger, after the phosphorous glass layer is removed, the silicon oxide film 13 is converted into phosphorous glass as shown in FIG. 1c.
A larger amount of the silicon nitride film 14 is removed than that of the silicon nitride film 14, and the silicon nitride film 14 remains in a canopy shape. If the metal electrode is formed in this state, a void 18 will be generated under the eaves as shown in FIG.
This was also a cause of decreased reliability.

The present invention eliminates the above drawbacks and provides a method for stably and easily manufacturing a semiconductor device with high yield and high reliability.

The present invention includes a step of sequentially depositing a silicon oxide film and a first silicon nitride film on a conductive base region of a silicon substrate, and selectively reaching the first silicon nitride film. After providing the first opening, a second opening having a larger area than the first opening is provided in the silicon oxide film, and a second silicon nitride film is formed by vapor phase growth. A second opening is coated on all sides of the silicon oxide film, thereby filling a portion of the second opening that is wider than the first opening, and filling the second opening with a second opening. forming a third opening that reaches the base region from the bottom and is surrounded by the second silicon nitride film, and then introducing phosphorus into the base region through the first and third openings. and forming an emitter region of opposite conductivity type, and after removing the phosphorus glass generated on the surface of the emitter region, the first and third
forming an emitter electrode connected to the emitter region through the opening of the semiconductor device.

Next, embodiments of the present invention will be described.

FIG. 2 is a manufacturing process sectional view showing an embodiment of the method for manufacturing a semiconductor device of the present invention.

First, a silicon oxide film 33 and a silicon nitride film 34 are sequentially deposited on an N-type silicon substrate 31 on which a P-type base region 32 is formed to a thickness of about 2000 Å and about 1000 Å, respectively (FIG. 2a).

Next, using the photoresist film as a mask, the silicon nitride film 34 is selectively removed to form an opening that reaches the silicon oxide film 33, and then, using the remaining silicon nitride film as a mask, the opening is removed. Then, in a self-aligned manner, a buffered hydrofluoric acid solution is used to form an opening in the silicon oxide film 3, which has a larger area than the opening and reaches the P-type base region 32 (FIG. 2b).

Next, a silicon nitride film 39 is grown to a thickness of approximately 1500 Å over the entire surface by vapor phase growth, and a thickness of approximately 200 Å is grown between the silicon nitride film 34 formed in the previous step and the silicon substrate.
A newly deposited silicon nitride film 39 is placed in the void of
(Figure 2c).

Next, the silicon nitride film 39 grown in the vapor phase in the previous step is removed by the thickness of the grown film, that is, about 1500 Å, in a controlled manner to expose the surface of the base region 32 (FIG. 2 d). .

Next, phosphorus is diffused through the openings provided in the previous step to form an N-type region, that is, an emitter region 36 in the base region 32, and then the phosphorus glass layer on the surface of the emitter region is removed (see Fig. 2). e).

Next, a photoresist film 35 is selectively formed, and using the photoresist film 35 as a mask, an opening reaching the base region 32 is provided (FIG. 2f).

Next, metal electrodes 37 and 3 made of aluminum are used to cover the opening and the opening provided on the upper surface of the emitter region 36 and to enable ohmic connection with the base region 32 and the emitter region 36.
7', 37'' are selectively formed (Fig. 2g).

In this example, since the periphery of the opening is formed with a homogeneous insulating film before phosphorus diffusion, the film layer of the phosphorus glass layer formed by phosphorus diffusion is the same, and after the phosphorus glass layer is removed. However, unlike the case of a two-layered structure, it does not form an eave-like structure. Further, in this embodiment, since the area of the emitter region can be reduced, it is suitable for manufacturing higher performance semiconductor devices.

As explained in detail above, according to the present invention,
The effect is great because a semiconductor device with high yield and high reliability can be obtained stably and easily.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main steps in manufacturing an example of a conventional semiconductor device, and FIG. 2 is a cross-sectional view of the manufacturing process showing an embodiment of the method of manufacturing a semiconductor device of the present invention. 11, 31...N-type silicon substrate, 12, 32
...P-type base region, 13,33...Silicon oxide film, 14,34...Silicon nitride film, 15,3
5... Photoresist film, 16, 36... N-type emitter region, 17, 37... Metal electrode, 18...
Void, 39...Insulating film.

Claims (1)

[Claims] 1. A step of sequentially depositing a silicon oxide film and a first silicon nitride film on a base region of one conductivity type of a silicon substrate, and a step of depositing a first silicon oxide film selectively on the first silicon nitride film. After providing the opening, a second opening having a larger area than the first opening is provided in the silicon oxide film, and a second silicon nitride film is grown by vapor phase growth into the second silicon oxide film. The silicon oxide film is deposited on all sides of the opening, thereby filling the part of the second opening that is wider than the first opening, and depositing the silicon oxide film from the first opening. forming a third aperture reaching the base region and surrounded by the second silicon nitride film; and then introducing phosphorus into the base region through the first and third apertures. a step of forming an emitter region of opposite conductivity type; and a step of forming an emitter electrode connected to the emitter region through the first and third openings after removing phosphorus glass generated on the surface of the emitter region. A method of manufacturing a semiconductor device, comprising: