JPS5947458B2 - How to form a resistor - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a semiconductor integrated circuit device.

A manufacturing method generally referred to as a washed emitter method is known as a manufacturing method for high frequency semiconductor integrated circuit devices.

In this method, a hole for forming an emitter layer is formed in an insulating film, and after impurities are diffused through the hole, the hole is used as a contact hole. In this way, the impurities will also diffuse under the insulating film around the contact hole, so there is no need to worry about the electrode formed in the contact hole coming into contact with semiconductors other than the emitter layer, and there is no need to insulate the electrode for forming the emitter layer. Since the film holes directly serve as contact holes, microfabrication becomes possible and high frequency transistors can be formed. Furthermore, if an electrode is formed on the emitter layer, which has a relatively shallow diffusion depth, by, for example, aluminum vapor deposition, silicon in the emitter layer will diffuse into the electrode formed of aluminum due to the heat during vapor deposition. In order to avoid defects in the junction surfaces of the layers, resulting in poor characteristics of the transistor, aluminum is used in which a small amount of silicon is contained in the aluminum (hereinafter, this metal is referred to as silicon-aluminum).By the way, semiconductor integrated circuits In many cases, devices have a built-in resistor.
In such cases, the impurity diffusion layer is used as a resistor. Moreover, in order to reduce the area occupied by the resistor and obtain high resistance, a different impurity diffusion layer is formed on the impurity diffusion layer (see Integrated Circuit Handbook Maruzen P493). Generally, in order to reduce the number of manufacturing steps as much as possible, the resistor is formed in parallel with the formation of the base layer of the transistor, and the impurity diffusion layer superimposed on the resistor is formed in parallel with the emitter layer of the transistor.

However, in this manufacturing method, if the transistor is formed using the washed emitter method as described above, the resistor may not have the desired resistance value, or breakage may occur in the resistor. I have found that it often happens that I get tired.

The reason for this is that at the same time as forming the emitter layer of the transistor, an impurity diffusion layer is formed which is superimposed on the resistor.
An oxide film formed during the diffusion on the surface of the emitter layer and the impurity diffusion layer is simultaneously removed, and a silicon-aluminum layer is formed on these surfaces by vapor deposition, and then formed on the emitter layer by a well-known selective etching method. Leave the silicon aluminum layer on and use it as an electrode.
It was found that the silicon-aluminum layer on the impurity diffusion layer was removed. In other words, in the selective etching, the etching solution for etching the silicon-aluminum layer is a mixture of an aluminum etching solution and a silicon etching solution.
This is because when the silicon-aluminum layer on the impurity diffusion layer is removed by etching, the silicon etching solution mixed in the etching solution also etches the impurity diffusion layer.

As a result of investigating these points, the inventor has arrived at the present invention.

Therefore, it is an object of the present invention to form a transistor in parallel with a washed emitter transistor. The present invention provides a method for manufacturing a semiconductor integrated circuit device in which a desired resistance value is obtained in a resistor and the resistor is not cut.

The gist of the present invention to achieve such objects is to fabricate a single transistor on a silicon semiconductor substrate. forming a first impurity layer to serve as a resistor in a region other than the base layer region at the same time as forming the emitter layer; a step of selectively removing to form a hole for impurity introduction, and at the same time forming a hole in the insulating film over a region of the center of the resistor; and introducing impurities through the hole formed in the step. forming an emitter layer of a transistor and a second impurity layer overlapping the resistor;
The new insulating film formed in the emitter layer and second impurity layer forming step is removed by a washed emitter method to form an electrode that is substantially the same as the impurity introduction hole for forming the emitter layer. forming a metal layer containing silicon on the semiconductor substrate surface-treated in this way and selectively etching it to form an electrode made of the metal layer in the electrode formation hole; The method of manufacturing a semiconductor integrated circuit device is characterized in that the metal layer is left also in a region where the second impurity layer formed so as to overlap the resistor is exposed.

This will be explained below using examples.

The drawings are cross-sectional process diagrams showing one embodiment of the method for manufacturing a semiconductor integrated circuit device according to the present invention.

As shown in FIG. 1, an N-type layer 2 is formed on, for example, a P-type silicon semiconductor substrate 1 by an epitaxial growth method.

Then, an oxide film 3 is formed which will serve as a mask for forming a selective diffusion layer in a subsequent step. Drawing b: Holes are made on the oxide film 3 in a region where a resistor according to the present invention is to be formed and a region where a base layer of a transistor is to be formed to expose the surface of the N-type layer 2.

Thereafter, P-type impurities are diffused through the holes to form P-type layers 4a and 4b. At this time, an oxide film is formed on P-type layers 4a and 4b by heat treatment during diffusion. Drawing c: The oxide film 3 and the oxide film formed during diffusion are removed, and a new oxide film 5 is formed by CVD (Chemi-CalVapOrD).
epOsitiOn) method.

This is done for the purpose of removing crystal defects at the interface between the oxide film and the semiconductor layer and forming an oxide film with a flat surface, and is not directly related to the present invention. Thereafter, an N-type layer is formed in a region across the surface of the P-type layer 4a that is to become a resistor, and in a region where an emitter layer is to be formed in the P-type layer 4b that is to become a base layer, and in the vicinity of the P-type layer 4b. Hole 6 in the area above 2
Form a, 6b, and 6c. An impurity diffusion layer 7a is formed by diffusing N+ type impurities through the holes 6a, 6b, and 6c formed in the previous process to cross the P type layer 4a, each of which becomes a resistor.
, an emitter layer 7b and a collector contact layer 7c of the transistor are formed.

An oxide film is formed on the surfaces of the diffusion layer 7a, emitter layer 7b, and collector contact layer 7c due to the heat treatment during the diffusion, and is removed by a well-known selective etching method (ie, washed emitter method). Drawing c: Two holes 3a are formed in the oxide film 5 on the P-type layer 4a, which is to become a resistor.
Open and P-type layer 4b which should become the base layer of the transistor
A hole 8b is made in the upper oxide film 5.

Drawing f: A silicon-aluminum layer is formed, for example, by vapor deposition, on the semiconductor substrate whose surface has been processed in this way, and then a P-type layer 4a to become a resistor is formed by a well-known selective etching method.
Two holes 8a1 formed in the upper oxide film 5 emitter layer 7
Of course, the silicon-aluminum layer is left as an electrode on the hole 6b made when forming the collector contact layer 7c, the hole 8b formed on the base layer, and the hole 6c made when forming the collector contact layer 7c. The silicon-aluminum layer is also left on the N+ type impurity layer 7a superimposed on the P type layer 4a which is to become the body.

If the silicon aluminum layer deposited on the N+ type impurity layer 7a superimposed on the P type layer 4a, which is to become a resistor, is removed because it is not an electrode, as in the conventional method, the N+ type layer is removed using a silicon-aluminum etching solution. The impurity layer and the P-type layer 4a are also etched, and due to this, the resistance value of the formed resistor cannot be obtained as desired.
In addition, the force z that was said to have caused the resistor to be cut was caused by the silicon--
If the aluminum layer remains, the above-mentioned problem will not occur.

Although this embodiment is described using a P-type silicon semiconductor substrate, it goes without saying that an N-type silicon semiconductor substrate may also be used.

However, in this case, the conductivity types of all other semiconductor layers must be reversed. Furthermore, although the transistor and the resistor are not separated by an isolation layer in this embodiment, it goes without saying that they may be separated by an isolation layer. As described above, according to the method for forming a resistor according to the present invention, a desired resistance value can be obtained for a resistor formed in parallel with a transistor formed by a washed emitter method, and the resistor will not be severed.

[Brief explanation of the drawing]

The drawings are cross-sectional process diagrams showing one embodiment of the method for manufacturing a semiconductor integrated circuit device according to the present invention.

Claims (1)

[Claims] 1. A step of forming a base layer of a transistor on a silicon semiconductor substrate and simultaneously forming a first impurity layer serving as a resistor in a region other than the base layer region, and forming an emitter layer within the base layer region of the transistor. a step of selectively removing the insulating film on a region where the impurities should be introduced to form a hole for introducing impurities, and simultaneously forming a hole in the insulating film on a region of the center of the resistor; a step of introducing an impurity through the hole formed to form an emitter layer of the transistor and a second impurity layer overlapping the resistor; and a step of forming the emitter layer and the second impurity layer. A step of removing the new insulating film using a washed emitter method to form a hole for forming an electrode that is substantially the same as the hole for introducing impurities for forming the emitter layer, and A metal layer containing silicon is formed on a semiconductor substrate and selectively etched to form an electrode made of the metal layer in the hole for forming the electrode, and a second impurity is formed so as to overlap on the resistor. A method of manufacturing a semiconductor integrated circuit device, characterized in that the metal layer is left also in areas where the layer is exposed.