JPH0414829A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a method which does not produce a residue of polycrystalline silicon or the like in the insulation and isolation operation by using a trench by a method wherein the surface of a second poly-Si film inside a groove is oxidized, the second poly-Si film is formed, an Si3N4 film is etched and removed wholly and the whole surface of a semiconductor substrate is covered with a third poly-Si film. CONSTITUTION:By using a mixed gas of trifluorosilane with hydrogen, a second poly-Si film 7 is grown selectively by a CVD method by using a first poly-Si film 6 as a nucleus; a groove 4 is filled completely with the second poly-Si film 7. Then, the second poly-Si film 7 which has been overflowed to the outside from the groove 4 is polished and removed or etched and removed by a polishing operation or an anisotropic etching operation; the surface of an Si substrate 1 is flattened. Then, the surface of the second poly-Si film 7 is oxidized by a thermal oxidation operation. A second SiO2 film 8 is formed; its surface can be formed in a position which is higher than the surface of a field SiO2 2. Consequently, no hollow is produced at the edge of the groove 4.

Description

[Detailed description of the invention] 〔overview〕 The present invention relates to insulation isolation technology for semiconductor devices.

Polycrystalline silicon (polyS) is used for insulation isolation using trenches.
The purpose is to obtain a method that does not produce residues such as i-film).

A first silicon dioxide ( a step of forming a SiO□) film, a step of coating a first poly-Si film on the surface of the groove, and a step of forming a first poly-Si film on the surface of the groove as a nucleus. selectively growing a second poly-Si film by chemical vapor deposition to completely fill the groove, and polishing the semiconductor substrate to remove by polishing or etching the first poly-Si film overflowing from the groove. and flattening the semiconductor substrate;
oxidizing the surface of the second poly-Si film in the trench to form a second poly-Si film;
N, a step of etching the entire surface of the film and covering the entire surface of the semiconductor substrate with a third poly-Si film;
The method is configured to include a step of selectively oxidizing the film to form electrode wiring.

[Industrial application field]

The present invention relates to insulation isolation technology for semiconductor devices.

In recent years, as an element isolation method that can achieve high-speed density and high-density integration, 1. A trench is formed in a silicon (Si) substrate, and the inside thereof is filled with a poly-Si film or the like and flattened. The so-called "trench isolation method" is widely used.

Furthermore, due to the demand for higher density, even in bipolar ICs, there are cases in which poly-Si film wiring is formed on a Si substrate.

[Conventional technology]

FIG. 2 is an explanatory diagram of a conventional example.

In the figure, 11 is a Si substrate, 12 is a field SiO
□ film, 13 is 5iJ4 film, 14 is groove, 15 is first Si
O □ membrane.

16 is the first poly-Si film, 17 is the second 5iOz film, 1
8 is the second poly-Si film, 19 is the third SiO2 film,
20 is electrode wiring A, 21 is electrode wiring B, 22 is poly-Si
It is a membrane residue.

Conventionally, the trench element isolation method involves first forming a trench 14 in a Si substrate 11, as shown in FIG. 2(a).

As shown in FIG. 2(b), a first 5in2 film 15 is formed by oxidizing the sidewall of the trench 14, and as shown in FIG. Growth of the first poly-Si film 16, as shown in FIG. 2(d), removal of unnecessary portions of the first poly-Si film 16 other than the grooves 14, as shown in FIG. 2(8).
As shown in FIG. 2, the second Sin film 17 was formed by oxidizing the surface of the first poly 5iWI 160 in the trench 14, in order.

[Problem to be solved by the invention]

However, in this method, a field S is formed on the Si substrate 11.
When there is a step due to the iO2 film 12 or the like, the surface of the first polygon 5illi 16 in the groove 14 must necessarily be lower than the bottom surface of the step.

Therefore, as shown in FIG. 2(f), a second poly-Si film 18 is coated on the Si substrate 11 formed by the conventional method.
As shown in FIG. 2(g), only the wiring part is covered with a 5iJa film (not shown), and the second poly-Si film 18 in other parts is selectively oxidized to convert it into a third 5in2 film, When poly-Si wiring is formed using the second poly-Si film 18 in the wiring portion, as shown in FIG. 2(g) and FIG. poly-Si
The film is not completely oxidized.

There is a problem that unnecessary polySt film residue 22 remains.

At this time, this poly-Si film residue 22 connects the electrode wiring A20 and the electrode wiring B21 of the poly-Si film in the form of a bridge, causing malfunction and characteristic defects as an element.

The present invention is provided for the purpose of obtaining a method in which no residue of the poly-Si film remains as described above.

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention and a schematic sectional view in the order of steps of an embodiment.

In the figure, ■ is a semiconductor substrate, 2 is a field SiO2
film, 3 is Si3N4 film, 4 is groove, 5 is first (7) SiO
.

6 is a first poly-Si film, and 7 is a second poly-Si film.

8 is the second (7) SiO2 film, 9 is the third po'JSi film,
10 is a third poly-Si film.

In the present invention, by a selective growth method of a poly-Si film, poly 5ill is grown only in the trench, and then two surfaces are planarized.

That is, one object of the present invention is to apply S to a semiconductor substrate 1 having a field SiO□ film 2, as shown in FIG. 1(a).
1 using an i3N4 film 3 and a PSG film (not shown) as a mask.
a step of forming grooves 4;

As shown in FIG. 1(b), the surface within the groove 4 is oxidized to form a first SiO2 film 5.

As shown in FIG. 1(C), including the surface inside the groove 4,
a step of coating the surface of the semiconductor substrate 1 with a first IJSt film 6;

As shown in FIG. 1(d), the inside of the groove 4 is left.

a step of removing the first poly-Si film 6 on the surface of the semiconductor substrate 1 by anisotropic etching;

As shown in FIG. 1(e), the first poly 5ilI! on the surface inside the groove 4! 6 as a core, a second poly S is formed in the groove 4.
1. A step of selectively growing the i-film 7 by chemical vapor deposition to completely fill the trench 4.

As shown in FIG. 1(f), the step of polishing the semiconductor substrate 1 and removing the second poly-Si film 7 overflowing from the groove 4 by polishing or etching to planarize the semiconductor substrate 1 and.

As shown in FIG. 1(g), the second poly-Si in the groove 4
a step of oxidizing the surface of the film 70 to form a second Sing film 8;

As shown in FIG. 1(h), the 5i on the semiconductor substrate 1
A step of removing the Jn film 3 by etching the entire surface and covering the entire surface of the semiconductor substrate 1 with a third poly-Si film 9.

As shown in FIG. 1(i), this is achieved by selectively oxidizing the third poly-Si film 9 to form a third SiO□ film IO.

[Effect]

In the present invention, the height of the surface of the poly-Si in the trench is not affected by the level difference in the substrate, and is not concave than the two peripheral parts. does not occur.

〔Example〕

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention in the order of steps.

An embodiment of the present invention will be explained with reference to FIG.

As shown in FIG. 1(a), a field SiO□ film 2 defining an element isolation region is formed on a Si substrate 1 by thermal oxidation to a thickness of 6,000 nm.

Next step, (by the VD method, the 5i3Na film 3 was
．． 000 people.

A PSG film (not shown) is deposited to a thickness of 1 μm and patterned. Deposit and pattern to a thickness of 2,000 nm.

Next, the Si-N4 film 3 and the PSG film were used as masks.

A groove 4 is formed by etching the Si substrate 1.

As shown in FIG. 1(b), by thermal oxidation method.

A first 5in2 film 5 is formed on the inner wall of the trench to a thickness of 2,000mm.

As shown in Figure 1(c), 500
The entire surface of the Si substrate 1, including the inner wall of the groove 4, is coated with a poly-Si film 6 having a thickness of fm<500 mm.

As shown in FIG. 1(d), the entire poly-Si film 6 on the surface of the Si substrate 1 is removed except for the inside of the groove 4 using anisotropic etching by RIE.

As shown in Figure 1(e), trifluorosilane (SiH
Cfs) and hydrogen (H2), i, oo
.

℃ by CVD method using the first poly-Si film 6 as a core.

A second poly-Si film 7 was selectively grown to a thickness of 2 μm.

A second poly-Si film 7 is completely buried in the trench 4.

As shown in FIG. 1(f), the second poly-Si overflows from the groove 4 by polishing or isomeric etching.
The film 7 is removed by polishing or etching to planarize the surface of the Si substrate 1.

As shown in FIG. 1(g), the surface of the second poly-Si film 7 is oxidized by thermal oxidation to form a second SiO□ film 8, which is similar to the field SiO□ film 2. Can be formed at a higher position than the surface. Therefore, no depressions are formed at the edges of the grooves 4.

Subsequently, as shown in FIG. 1(h), a third poly-Si film 9 is coated by the CVO method, and as shown in FIG. 1(i), a 5iJn film (not shown) is used as a mask.

The parts other than wiring formation are oxidized to form a third layer for wiring insulation isolation.
The remaining third poly-Si film 9
is formed as an electrode wiring.

〔Effect of the invention〕

As explained above, according to the present invention, the dent in the -1 part of the groove that occurs in the conventional method is eliminated, and the generation of residue of the poly-Si film for wiring in that part is prevented. Prevented.

As a result, a stable groove surface shape can be obtained without being affected by surface differences in other parts of the semiconductor substrate. We greatly appreciate your feedback regarding its characteristics and reliability.

3, S;sNd Australia 5'th,)σIi'l,'US1 gland

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention in the order of steps, and FIG. 2 is an explanatory diagram of a conventional example. In the figure, 1 is the semiconductor substrate 1, 2 is the field 5i02, film 3 is S
i 3 N 4WI:, 4 is the groove. 5 is the first 5iOz film, and 6 is the first poly-Si film. 7 is the second poly-Si film, 8 is the second Sing film 9 is the third
poly-Si film, 10 is the third SiO2 film; 4: Actual example of the invention θ-) L Takemehara゛/da];2's S;(,')J Chikomasu City: 4 Kim Majesty'1 station f loga I ka f da j's essence - Ming 1 and']

Claims (1)

[Claims] A step of forming a groove (4) in a semiconductor substrate (1) having a field oxide film (2) using a silicon nitride film (3) and a phosphosilicate glass film as a mask; ) to form a first silicon dioxide film (5); coating the surface within the groove (4) with a first polycrystalline silicon film (6); The first polycrystalline silicon film (6) on the surface within the groove (4)
A second polycrystalline silicon film (
7) is selectively grown by chemical vapor deposition to form the groove (4).
complete filling of the semiconductor substrate (1), polishing or etching away the first polycrystalline silicon film (6) overflowing from the groove (4), and removing the first polycrystalline silicon film (6) from the groove (4); oxidizing the surface of the second polycrystalline silicon film (7) in the groove (4) to form a second silicon dioxide film (8); 1) removing the silicon nitride film (3) on the entire surface by etching and covering the entire surface of the semiconductor substrate (1) with a third polycrystalline silicon film (7); (7) is selectively oxidized to form electrode wiring (9)
1. A method of manufacturing a semiconductor device, the method comprising: forming a semiconductor device.