JPS6365664A - Manufacture of semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To enable obtaining a semiconductor integrated circuit which has no disconnection of an electrode wiring and has a reliability-improved circuit resistance by forming a resistor layer by patterning after making the distributed concentration of an impurity introduced in a polysilicon layer uniform by a low temperature treatment. CONSTITUTION:A polysilicon layer is formed on all the surface by vapor growth after the first oxide film 2 made of SiO2 is formed on the surface of a P-type semiconductor substrate 1. Then, after a great quantity of a P-type impurity is diffused in the polysilicon layer by ion implantation, heat-treated for about 10-120 minutes at a low temperature (650-800 deg.C) and the concentration distribution of the impurity introduced by the ion implantation is made uniform. Then, part of the polysilicon layer is removed by etching by using a normal photolithography and then, the second oxide film 4 is formed on all the surface by vapor growth. After annealing a resistor layer 3 made of polysilicon by a high temperature heat treatment (950-1000 deg.C), an electrode for drawing characteristics 5 is formed and a circuit resistance is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor integrated circuit, and particularly to a method of manufacturing a circuit resistor.

[Conventional technology]

A method of manufacturing a conventional circuit resistor formed in a semiconductor integrated circuit will be described with reference to FIGS. 2(a) to 2(c).

First, as shown in FIG. 2(a), a first oxide film 2 is formed by thermally oxidizing the surface of a P-type semiconductor substrate 1, and then a polysilicon layer is formed over the entire surface by a normal vapor phase growth method. Then P
After a large amount of type impurity is diffused into the polysilicon layer by ion implantation, the polysilicon layer is patterned by ordinary photolithography to form resistor layer 3.

Next, as shown in FIG. 2(b), a second oxide film 4 is formed on the entire surface by a normal vapor phase growth method.Next, as shown in FIG.
As shown in c), a portion of the second oxide film layer 4 is removed by etching to expose a portion of the resistor layer 3. Subsequently, the resistor layer 3 made of polysilicon is annealed by high-temperature heat treatment (950 to 1000° C.), and then an electrode 6 for extracting characteristics is formed to complete the circuit resistance.

[Problem that the invention seeks to solve]

However, in the conventional circuit resistor manufacturing method described above, etching of the polysilicon layer is performed immediately after introducing P-type impurities by ion implantation.
As shown by the line, due to the uneven impurity concentration distribution,
By using either the ordinary plasma etching method or the dilute fluorinitrate etching method, the side wall 3B of the resistor layer 3 made of polysilicon is processed into an overhang shape as shown in FIG. 2(a). As a result, there are problems such as the photoresist layer and the metal layer for electrodes being formed thinly in the subsequent photolithography process, and disconnections occurring in the electrode wiring, resulting in a decrease in reliability.

An object of the present invention is to provide a method for manufacturing a semiconductor integrated circuit having circuit resistance with improved reliability.

[Means for solving problems]

The method for manufacturing a semiconductor integrated circuit of the present invention includes the following steps: - forming an insulating film on a conductivity type semiconductor substrate; forming a polysilicon layer on the insulating film; and doping impurities of one conductivity type in the polysilicon layer. The method includes a step of performing low-temperature heat treatment after ion implantation, a step of patterning the heat-treated polysilicon layer to form a resistor layer, and a step of subjecting the resistor layer to high-temperature heat treatment.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(c) are cross-sectional views of a semiconductor chip shown in order of steps for explaining an embodiment of the present invention.

First, as shown in FIG. 1(a), a P-type semiconductor substrate 1
After forming the first oxide film 2 made of S t 02 on the surface, a polysilicon layer is formed on the entire surface by vapor phase growth. Next, a large amount of P-type impurity is diffused into the polysilicon layer by ion implantation, and then heated at a low temperature (650 to 800℃).
) for about 10 to 120 minutes to make the concentration distribution of impurities introduced by ion implantation uniform as shown by line B in FIG. Next, a portion of the polysilicon layer is etched away using conventional photolithography.

Next, as shown in FIG. 1(b), a second oxide film 4 is formed over the entire surface by vapor phase growth.

Next, as shown in FIG. 1(C), the resistor layer 3 made of polysilicon is annealed by high-temperature heat treatment (950 to 1000°C) in the same way as in the conventional manufacturing method, and then the electrode 5 for extracting characteristics is formed. and complete the circuit resistance.

In this embodiment, the etching of the polysilicon layer is performed after the impurity concentration distribution is made uniform by low-temperature heat treatment after ion implantation, so that the sidewall 3A of the resistor layer 3 has an overhang shape as in the conventional etching process. There is no longer any fear of becoming As a result, the photoresist layer and the metal layer for electrodes are not formed thinly in the photolithography process, and the electrode wiring is not broken, so that reliability can be greatly improved.

In the above example, the low temperature heat treatment temperature was 650 to 80.
Although 0°C was applied, 850°C to 1000°C is optimal considering the cross-sectional shape of the side wall of the resistor layer. However, 9
Various diffusion layers that are already formed at temperatures above 00°C,
In particular, since the depth of the base low-temperature diffusion layer of a bipolar transistor varies to a degree that cannot be ignored, heat treatment at 800° C. or higher is actually impossible.

〔Effect of the invention〕

As explained above, the present invention introduces impurities into a polysilicon layer, performs low-temperature treatment to make the distribution concentration of the impurities uniform, and then patterns it to form a resistor layer, which eliminates disconnection of electrode wiring and provides reliability. A semiconductor integrated circuit having improved line resistance can be obtained.

[Brief explanation of the drawing]

1(a) to 1(C) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining one embodiment of the present invention, and FIG. 2(a)
) to (C) are cross-sectional views of a semiconductor chip shown in the order of steps to explain a conventional method of manufacturing a semiconductor integrated circuit, and FIG. 3 shows the relationship between the depth and impurity concentration of a resistor layer made of polysilicon. It is a diagram. DESCRIPTION OF SYMBOLS 1... P-type semiconductor substrate, 2... First oxide film, 3...
...Resistor layer, 3A, 3B... Side wall, 4... Second oxide film, 5... Characteristic extracting electrode. Muscle 1 diagram

Claims (1)

[Claims] A step of forming an insulating film on a semiconductor substrate of one conductivity type, a step of forming a polysilicon layer on the insulating film, a step of ion-implanting an impurity of one conductivity type into the polysilicon layer and then performing low-temperature heat treatment, and heat treatment. A method for manufacturing a semiconductor integrated circuit, comprising the steps of: patterning the polysilicon layer to form a resistor layer; and subjecting the resistor layer to high-temperature heat treatment.