JPS60116160A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the temperature dependency by forming a sllicon layer by reduced-pressure vapor phase growing method of the prescribed temperature or lower on an insulating film of the substrate and forming a silicon layer implanted with impurity as a resistor, thereby increasing the gray size. CONSTITUTION:An insulating film 2 is formed by silicon oxidation on a semiconductor substrate 1, and a polycrystalline silicon layer 3 is formed by reduced- pressure vapor phase growing method at 580 deg.C or lower on the film 2. Then, an impurity is doped in the layer 3 by the prescribed treatment to form a resist film, then the resist film is selectively removed by a photoetching. Then, with the remaining resist film as a mask the layer 3 is etched by plasma in the desired shape. Then, an insulating film 4 is formed on the layer 3, it is then heat treated at the prescribed temperature range to activate the impurity, thereby increasing the gray size to reduce the temperature dependency of the resistor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a novel method for manufacturing a semiconductor device, and in particular to a method for manufacturing a novel semiconductor device that can form a resistor with small temperature dependence using polycrystalline silicon. This is what we are trying to provide.

BACKGROUND ART AND PROBLEMS There is a technique for forming a resistor made of polycrystalline silicon in a monolithic IC, but the resistor is generally formed as follows.

60% by low pressure vapor phase growth method on the insulating film on the surface of the semiconductor substrate.
forming a polycrystalline silicon layer at a temperature of 0 to 660'O;
A resistor is then formed by doping the polycrystalline silicon layer with conductive impurities, followed by activation heat treatment, and then selectively etching the polycrystalline silicon layer into a predetermined pattern.

However, there is a problem in that the resistor made of polycrystalline silicon formed in this manner has a negative temperature coefficient of resistance, and the absolute value of the temperature coefficient of resistance increases as the specific resistance increases.

OBJECTS OF THE INVENTION It is therefore an object of the present invention to provide a novel method for manufacturing a semiconductor device in which a resistor with small temperature dependence can be formed using polycrystalline silicon.

Summary of the Invention In order to achieve the above object, the method for manufacturing a semiconductor device of the present invention includes forming a silicon layer on an insulating film formed on the surface of a semiconductor substrate by a low pressure vapor phase epitaxy method at a temperature of 580° C. or lower; The feature is that impurities are introduced into the silicon layer to make the silicon layer a resistor.

EXAMPLE The method for manufacturing a semiconductor device of the present invention will be explained in detail in accordance with the example shown in the attached 14 drawings.
D) is a cross-sectional view of a semiconductor substrate showing an example of a method for manufacturing a semiconductor device of the present invention in the order of manufacturing steps.

(A) A silicon oxide film 2 is formed on the upper surface of a wafer-shaped semiconductor substrate 1 made of single crystal silicon by thermal oxidation or vapor phase growth. This step of forming silicon oxide film 2 is only for forming a resistor made of polycrystalline silicon! It is not a special process, but forms part of the process for forming bipolar I transistors, etc.

(B) Next, a polycrystalline silicon layer 3 is formed on the upper surface of the silicon oxide film 2 by thermal decomposition of a gas such as a silane compound by low pressure vapor phase growth. This vapor phase growth is not performed at a temperature of 600 to 680°C as in the conventional method, but is performed at a temperature of 580″C or lower, for example, 540°C.

(C) Next, the polycrystalline silicon layer 3 is doped with an impurity by, for example, ion implantation, doped oxide, pre-deposition, or the like.

(D') Next, a resist film is formed, the resist film is selectively removed by photo processing, the remaining resist film is masked, and the polycrystalline silicon layer 3 is etched using CF4 plasma or the like to obtain the desired shape. do.

Next, an insulating film 4 such as a silicon oxide film is formed on the surface of the polycrystalline silicon layer 3 for the purpose of preventing out-diffusion of impurities, protecting the surface, and preventing oxidation.
The impurities are activated by heat treatment at an appropriate temperature within the range of 00 to 1100'O.

Thereafter, the film 4 is selectively etched to form a window 5 for taking out the electrode, and then an electrode 6 is formed on the semiconductor substrate 1.

In this way, by setting the temperature at which the polycrystalline silicon film 3 is formed by vapor phase growth to 580° C. or lower, for example 540° C., the temperature dependence of the resistor can be reduced. Figure 2 shows the case where the polycrystalline silicon film 3 is grown in vapor phase at a temperature of 540°C and the conventional case where the temperature is 650°C.
It shows the temperature characteristics of resistance when it is set to °C. This characteristic is based on the conditions that the thickness of the polycrystalline silicon film 3 is 1000 nm, the doped impurity is phosphorus P, and the resistivity p is IonΩ・Cm, and only the temperature during vapor phase growth is 540°C16.
The results were obtained by measuring resistors formed at 50° C. in two ways.

As is clear from this figure, the temperature coefficient of resistance of the polycrystalline silicon film 3 stops in the region of low resistivity, but when the resistivity increases beyond a certain level, the temperature coefficient of resistance becomes negative, and its absolute value is the resistivity. The higher the value, the larger the value. Therefore, when the resistivity is increased to use a polycrystalline silicon film as a resistor, the temperature coefficient of resistance is negative and its absolute value becomes so large that it cannot be ignored. However, when the polycrystalline silicon film 3 is grown in a vapor phase, If the temperature is lower than normal, for example, 540°C, as in the present invention, the temperature coefficient of resistance will be smaller than the normal temperature, for example, 650°C, and the temperature change range will normally be smaller. At 00C to 80°C, the temperature coefficient of resistance is -1000 to -2000ppm/”
It becomes C. However, if the temperature during vapor phase growth is lowered to 540'C, -5
00 to -200i) ppm 10C, and the temperature dependence can be reduced by 2 minutes.

The reason why silicon properties change as described above when the temperature at which a silicon film is formed by vapor phase growth is lowered is as follows. In other words, the vapor phase growth temperature is generally 600 to 660 degrees Celsius due to the vapor growth rate and other aspects. become.

Then, grains grow through subsequent heat treatment.

On the other hand, when a silicon film is vapor-phase grown at a temperature of 580° C. or lower, the silicon film becomes nearly amorphous at the vapor-phase growth stage. Then, during subsequent heat treatment, the silicon film becomes polycrystalline.

In this way, when recrystallization progresses from an amorphous state to a polycrystalline state, the grain size becomes larger than when recrystallization progresses from polycrystalline to polycrystalline. Therefore, the density of traps existing along the grain boundary is also low. Since the temperature characteristics of polycrystalline silicon are largely controlled by the temperature characteristics of the traps (1), the lower the trap density, the smaller the temperature dependence of the resistance.

Effects of the Invention As stated above, the method for manufacturing a semiconductor device of the present invention has the following effects:
Forming a silicon layer on an insulating film formed on the surface of a semiconductor substrate by low pressure vapor phase growth at a temperature of 580°C or less, and introducing impurities into the silicon layer to make the silicon layer a resistor. It is characterized by: Therefore, according to the present invention, the silicon film is in an amorphous state when it is grown in a vapor phase, and becomes a polycrystalline state only when it is subjected to a subsequent heat treatment. As a result, the grain size increases and the density of traps along the grain boundaries decreases, resulting in less temperature dependence. Therefore, it is possible to form a resistor made of polycrystalline silicon with low temperature dependence.

[Brief explanation of drawings]

1A to 1D are cross-sectional views of a semiconductor substrate showing an example of the method for manufacturing a semiconductor device of the present invention in the order of steps, and FIG. 2 is a diagram showing the correlation between the temperature coefficient of resistance and resistivity. FIG. 3 is a diagram showing a resistor made of polycrystalline silicon formed by the method shown in 1 and a resistor made of polycrystalline silicon formed by a conventional method. Explanation of symbols: i--semiconductor substrate, 2--insulating film, (polycrystalline) silicon film

Claims (1)

[Claims] (1) 580 nm on the insulating film formed on the surface of the semiconductor substrate.
A method for manufacturing a semiconductor device, comprising forming a silicon layer by low pressure vapor phase growth at a temperature of 0.degree. C. or lower, and introducing impurities into the silicon layer to make the silicon layer a resistor.