JPH04107949A - Semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To prevent the occurrence of crystal defects at the time of conducting the separation of elements of a semiconductor device by forming grooves having the width and space of specific dimensions, by forming a thermal oxide film having a predetermined film thickness at a specific oxidation temperature on the surface of the groove and by embedding the oxide film in the groove. CONSTITUTION:Grooves having the width of 1mum and below and space of 1mum or more are provided, a thermal oxide film having the film thickness of about l/10 of the groove width is provided by a heat treatment at 950 deg.C and below and the oxide film is embedded in the groove so that a separation between elements is conducted. Also, the surface of the device is provided with grooves having the width of 0.6mum and below and space of 1mum or more and the oxide film is embedded in the grooves. Thus, even if the separation between elements is conducted by a trench isolation, no crystal defect occurs and it is possible to avoid the abnormal operation of a transistor, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The first invention relates to a method for manufacturing a semiconductor device, particularly to a method for isolating elements.

This second invention relates to a semiconductor device, particularly a semiconductor device in which elements are isolated.

[Conventional technology]

In semiconductor integrated circuits, particularly in devices called LSIs, many devices are arranged on the same plane, and the devices must be electrically insulated to avoid malfunctions due to mutual interference. In order to perform this so-called isolation between elements, a method called trench isolation has conventionally been used.

This will be explained with reference to the drawings. FIGS. 2(a) to 2(d) are cross-sectional views showing an example of trench isolation,
The steps are shown in order. After forming a buried collector layer 2 by diffusing impurities into a silicon substrate 1, an epitaxial growth layer 3 is formed. Next, a first oxide film 4 is formed on the epitaxial growth layer 3. Next, the first oxide film 4 is patterned by a photolithography process, and using this as a mask, the silicon substrate 1 is etched deeper than the buried collector layer 2 to form a groove 5 (FIG. 2(a)).

Next, a thin second oxide film 6 having a thickness of, for example, about 1/10 of the width W of the groove 5 is formed on the surface of the groove 5 by thermal oxidation (FIG. 5(b)). Next, a buried oxide film 7 is formed by CVD or the like to fill the groove 5 (FIG. 3(C)). Thereafter, the buried oxide film 7 and the first oxide film 4 are etched back so that the surfaces thereof are flat, and then the base region 8. An emitter region 9 is formed in the element formation region 10 ((d) in the same figure).
)). Furthermore, although not shown, electrodes, wiring interlayer insulating films, etc. are formed to form a plurality of separated elements.

[Problem to be solved by the invention]

Conventional trench isolation consists of the steps described above, but the width W of the groove 5 and the interval S between adjacent grooves 5
, and depending on the value of the oxidation temperature T when forming the second oxide film 6, crystal defects may occur in the element formation region 10 during the formation of the buried oxide film 7 due to stress etc. There is a problem in that a transistor or the like having a base region of 8 degrees and an emitter region of 9 does not operate normally.

The present invention was made to solve the above-mentioned problems, and includes a method for manufacturing a semiconductor device and a method for manufacturing a semiconductor device, which does not generate crystal defects even when elements are separated by trench isolation, and can avoid abnormal operation of transistors, etc. The purpose is to obtain equipment.

[Failure to solve the problem]

In the method for manufacturing a semiconductor device according to the first invention, a width of 1
Provide grooves with an interval of 1 μm or more, and 1/1 of the width of the groove.
A thermal oxide film having a thickness of about 0 is provided by heat treatment at 950° C. or less, and the inside of the trench is filled with the oxide film to provide isolation between elements.

Further, the semiconductor device according to the second invention has a width of 0.6μ on the surface.
Grooves with an interval of 1 μm or more are provided, and the inside thereof is filled with an oxide film.

[Effect]

The width of the groove is 1 μm or less and the interval is 1 μm or more, and a thermal oxide film of about 1/10 of the groove width is formed in this groove by heat treatment at 950°C or less, and the inside of the groove is filled with the oxide film to improve the periphery of the groove. relieve stress.

In addition, the width of the groove is 0.6 μm or less, the interval is 1 μm or more,
The stress around the trench is alleviated by filling the inside of the trench with an oxide film.

〔Example〕

FIG. 1 shows an overview of the present invention; the relationship among the defect density (number of defects per 1 μm2) in the element formation region 10, the width W and spacing S of the groove 5, and the oxidation temperature T during the formation of the second thermal oxide film 6. This is Kura 7, which showed the following. The variation in the measured values in the figure indicates the difference between the edge and center of the 5'φ substrate. In the method described in the prior art section, the width W, the interval S, and the oxidation temperature T are
The inventor has discovered that when various selections are made, the density of defects occurring in the element forming region 10 changes as shown in the figure.

That is, in the case where the width W of the groove 5 is 1.0 μm or less and the interval S between adjacent grooves 5 is 1 μm or more, the temperature T must be set to 950° C. or less in order to reduce the defect density to O. I know it's good.

Furthermore, as is clear from FIG. 1, when the oxidation temperature T is high and the width W of the groove 5 increases, there is a tendency for the number of defects to increase. The density becomes 0. That is, the interval S between the grooves 5 is 1
When it is more than μm! The same effect can be obtained even if the width W of 45 is set to 0.6 μm or less.

However, the thickness of the second thermal oxide film 6 is 1 of the width W of the groove 5.
/10 or so. This is because if it is too thick, the shape of the groove 5 will be deformed, and if it is too thin, the film thickness will be uneven and stress will occur.

〔Effect of the invention〕

As explained above, this first invention forms grooves with a width of 1 μm or less and an interval of 1 μm or more when performing element isolation of a semiconductor device, and oxidizes the surface of the grooves at an oxidation temperature of 950° C. or less. Since a thermal oxide film with a thickness of about 1/10 of the width is formed and the inside of the groove is filled with the oxide film, stress around the groove is relaxed, crystal defects are prevented from occurring, and abnormal operation of the element can be avoided. There is an effect.

As explained above, this second invention has a plurality of grooves on the surface filled with an oxide film having a width of 0.6 μm or less and an interval of 1 μm or more, so that stress around the grooves is reduced. This has the effect of allowing element isolation while preventing crystal defects from occurring.

[Brief explanation of drawings]

Figure 1 is a graph showing the outline of this invention, Figure 2 (a) -
(d) is a cross-sectional view showing the trench isolation process in order of process. In the figure, 1 is the semiconductor substrate, 5 is the groove, 6 is the second oxide film, W is the width of the groove, S is the interval between the grooves, and T is the oxidation temperature. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) A method for manufacturing a semiconductor device including an element isolation step of forming grooves on the surface of the semiconductor device, the step of forming grooves with a width of 1 μm or less and an interval of 1 μm or more on the surface of the semiconductor substrate; 1/ of groove width at oxidation temperature below ℃
1. A method for manufacturing a semiconductor device, comprising: forming a thermal oxide film with a thickness of about 10 mm; and burying the inside of the trench with an oxide film. (2) A semiconductor device characterized in that its surface is provided with a plurality of grooves filled with an oxide film, each having a width of 0.6 μm or less and an interval of 1 μm or more.