JPH025299B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method of manufacturing a bipolar semiconductor device having a shot barrier diode.

Conventionally, in bipolar semiconductor devices, in order to prevent aluminum used as an electrode or a material containing aluminum as a component from reacting with silicon and short-circuiting the emitter-base junction or base-collector junction, Formation of crystalline silicon films is being practiced. In addition, in such bipolar semiconductor devices, shot barrier diodes are also added, but since no polycrystalline silicon film must exist in that region, a manufacturing process that is compatible with this is required. is necessary.

1 to 5 are side cross-sectional views of the main parts of the device at key points in the process for explaining a typical method for manufacturing the above-mentioned bipolar semiconductor device. The conventional method will be described with reference to the figures.

See Figure 1 (1) The silicon semiconductor substrate 1 (actually an epitaxially grown (n-type) silicon semiconductor layer) has a (p
It is assumed that a base region 2 (type) is formed and its surface is covered with a field oxide film 3. Furthermore, B
is the base forming area, S is the shotgun barrier,
This is a diode formation region.

(2) The field oxide film 3 is patterned using ordinary photolithography technology to form a window 3S for forming a shot barrier diode, a window 3E for forming an emitter, and a window 3B for forming a base contact. At this point, the etching is stopped without penetrating each window, leaving a film thickness of about 1000 Å. Note that the symbol 4 indicates a photoresist film. This photoresist film 4 is of a negative type.

Refer to FIG. 2 (3) A photoresist film 5 having a pattern exposing the emitter forming window 3E and the base contact forming window 3B is formed. This photoresist film 5 is also of a negative type.

(4) Etching the oxide film 3 to penetrate the emitter forming window 3E and the base contact forming window 3B.

Refer to FIG. 3 (5) All photoresist films 4 and 5 are removed.

(6) A new photoresist film mask is formed, and using this mask, an impurity of conductivity type opposite to that of the base region 2 is introduced to form the emitter region 6.

(7) The photoresist film is removed, and a polycrystalline silicon film 7 is formed to a thickness of, for example, about 800 Å by low-temperature chemical vapor deposition.

(8) Window 3 for forming shot barrier diode
A photoresist film 8 having an opening exposing S is formed.

Refer to FIG. 4 (9) Using the photoresist film 8 as a mask, the polycrystalline silicon film 7 is patterned to expose a part of the oxide film 3.

Refer to FIG. 5 (10) The acid oxide film 3 is etched to penetrate the window 3S for forming the shot barrier diode. Note that when etching the oxide film 3, it is optional to form a new photoresist film mask if necessary.

(11) After this, the photoresist film 8 is removed, and the first layer of aluminum electrodes and wiring is formed, and other necessary steps are taken to complete the device.

According to this conventional technique, it is possible to prevent polycrystalline silicon from adhering to the substrate surface on which the shot barrier diode is formed. However, this requires a process using two layers of photoresist films. For this reason, a negative type photo resist must be used.

Generally, positive type photo resists are more suitable for forming fine patterns than negative type photo resists. However, when using two positive type photo resists,
When applying layers, apply the first layer when applying the second layer.
The photoresist film of each layer is dissolved. Therefore,
Positive type photoresists cannot be used in the process.

In the present invention, a thin oxide film is present in the shot barrier diode formation region without using a two-layer structure of photoresist film, thereby preventing the deposition of polycrystalline silicon. Explain in detail.

6 to 8 are sectional side views of essential parts of a semiconductor device at key points in the process for explaining one embodiment of the present invention, and the following description will be made with reference to these figures.

Refer to FIG. 6 (1) The silicon semiconductor substrate 11 has a base region 12.
is formed, and the surface is covered with a field oxide film 13.

(2) Applying normal photolithography technology,
The oxide film 13 is patterned using the photoresist film 14 as a mask to form a window 13S for forming a shot barrier diode, a window 13E for forming an emitter, and a window 1 for forming a base contact.
Form 3B. Of course, a positive type photoresist film 14 may be used.

Refer to FIG. 7 (3) After removing the photoresist film 14, a silicon nitride film 17 is formed by applying chemical vapor deposition.

(4) Window 1 for forming shot barrier diode
A photoresist film 15 having an opening exposing only 3S is formed.

Refer to FIG. 8 (5) Using the photoresist film 15 as a mask, the silicon nitride film 17 is patterned to expose the surface of the substrate 11 within the window 13S for forming a shot barrier diode.

(6) After removing the photoresist film 15, selective thermal oxidation is performed using the silicon nitride film 17 as a mask to form a film with a thickness of, for example, about 1000 Å in the window 13S for forming the shot barrier diode. A silicon dioxide film 16 is formed.

(7) Thereafter, the device is completed by performing a series of processes such as forming an emitter region by performing steps exactly the same as step (6) and subsequent steps in the prior art described above.

As can be seen from the above description, according to the present invention, when manufacturing a semiconductor device that has a polycrystalline silicon film that suppresses the reaction between aluminum and silicon and is equipped with a shot barrier diode, Since a structure in which a polycrystalline silicon film is not formed in the shot barrier diode formation region can be adopted without using a two-layer structure of photoresist films, any photoresist such as a positive type can be used. Therefore, compared to the case where a negative type photoresist is used, finer patterns can be formed, and the degree of integration of the device is improved.

[Brief explanation of drawings]

1 to 5 are side cross-sectional explanatory views of main parts of a semiconductor device at key points in the process for explaining the conventional technology;
6 to 8 are side cross-sectional views of essential parts of a semiconductor device at key points in the process for explaining one embodiment of the present invention. In the figure, 11 is a substrate, 12 is a base region,
13 is an oxide film, 14 is a photoresist film, 15
16 is a photoresist film, 16 is a silicon dioxide film, and 17 is a silicon nitride film.

Claims (1)

[Claims] 1. Patterning an oxide film on a semiconductor substrate to form windows including windows for forming a shot barrier diode, exposing the surface of the substrate within the windows, and forming windows for forming a shot barrier diode. An oxidation-resistant film is formed that has an exposed opening and covers the other windows, and selective oxidation is performed using the oxidation-resistant film as a mask to expose the inside of the window for forming the shot barrier diode. 1. A method of manufacturing a semiconductor device, comprising the steps of forming an oxide film covering the surface, removing the oxidation-resistant film, and then forming a polycrystalline silicon film.