JPH081926B2 - Method for manufacturing isolation groove - Google Patents

Description

The present invention relates to a method for manufacturing an insulation separation groove in a semiconductor device, and more particularly to a method for manufacturing an insulation separation groove in which a groove is filled with an insulating material made of silicon oxide.

[Conventional technology]

An example of a conventional manufacturing method of this type is shown in the vertical sectional views of FIGS. 3 (a) and 3 (b).

First, as shown in FIG. 3A, boron-phosphorus-silicate glass (BPSG) 3 is deposited by vapor phase growth method in a groove 2 formed for the purpose of insulating and separating the elements of the semiconductor substrate 1. At this time, oxygen BPSG3, for example tetraethyl ortho-silicate and _{(Si (OC 2 H 5)} 4) and trimethyl borate as the main raw material (B (OCH _{3) 3)} and phosphine (PH ₃₎ ( O
₂ ) and can be mixed and pyrolyzed under reduced pressure to form.

In this case, generally, a void 4 as shown in FIG. However, in this state
When heat treatment at 900-1000 ℃ is performed, as shown in Fig.
The void 4 disappears and the inside of the groove 2 is completely filled with BPSG3.

After that, BPSG3 existing on the surface of the semiconductor substrate 1 is removed by etching to manufacture the insulating separation groove.

[Problems to be Solved by the Invention]

In the above-described conventional manufacturing method, the void 4 generated when the inside of the groove 2 is filled with BPSG3 is eliminated during the subsequent heat treatment. At the time of this elimination, the BPSG3 existing above the groove 2 fills the void 4. It is a complicated mechanism. As a result, the film thickness of BPSG3 in the upper portion of the groove 2 is thinned in the groove 2 by an amount corresponding to the volume of the void 4.

Therefore, as shown in FIG. 4 (a), when applied to the semiconductor substrate 11 having the densely concentrated grooves 12a and the sparse grooves 12b, the BPSG13 on the densely concentrated grooves 12a is formed. Is thinner than the film thickness on the rough groove 12b. Therefore, when the BPSG3 on the semiconductor substrate 11 is completely removed by etching, as shown in FIG.
The BPSG 13 of a is excessively etched, and the unevenness of the surface of the semiconductor substrate 11 in this region becomes severe. These irregularities adversely affect the elements formed on the semiconductor substrate 11, especially the disconnection of metal wiring, and lower the reliability of the semiconductor device and the reduction in product yield.

An object of the present invention is to provide a method for manufacturing an insulation separation groove that does not cause surface irregularities.

[Means for solving the problem]

According to the method of manufacturing an insulating separation groove of the present invention, in a region including a groove provided in a semiconductor substrate, silicon oxide is mainly used and any one of Group 3, Group 4 and Group 5 as impurities or a combination thereof is used. A step of forming a silicate glass containing an element by chemical vapor deposition, a step of etching and removing the silicate glass until the voids formed in the silicate glass in the groove are exposed, and a heat treatment is performed. A step of once melting the silicate glass, a step of forming a silicate glass containing the same or different impurities as the silicate glass on the entire surface by a chemical vapor deposition method, and etching the silicate glass on the semiconductor substrate And a removing step.

[Action]

In the above-described manufacturing method, since the silicate glass is melted only in the grooves and the silicate glass is removed by etching again, each groove is subjected to each step under substantially the same condition, and thus the density of the grooves is increased. Filling of silicate glass is realized regardless of.

〔Example〕

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

FIGS. 1A to 1D are vertical sectional views showing an embodiment of the present invention in the order of manufacturing steps.

First, as shown in FIG. 1A, an insulating separation groove 2 formed in a semiconductor substrate 1 for the purpose of insulating and separating the elements of a semiconductor device.
Boron / phosphorus / silicate glass (BPSG) 3 is deposited therein by a low pressure vapor phase epitaxy method. This BPSG3 is formed by thermal decomposition by mixing trimethyl borate, phosphine and oxygen with tetraethyl orthosilicate as the main raw material as in the conventional method. The BPSG3 is formed so that the contents of boron and phosphorus contained therein are 3 to 4% by weight and 4 to 5% by weight, respectively. As a result, as in the conventional case, the groove 2
A void 4 is generated inside the.

Next, as shown in FIG. 2B, BP on the surface of the semiconductor substrate 1
SG3 is removed by etching, and further etching is performed until the void 4 inside the groove 2 is exposed.

Then, when heat treatment is performed at 900 to 1000 ° C. in this state, BPSG3 flows and accumulates in a gentle shape on the bottom side in the groove 2 as shown in FIG. 2C, and the void 4 inside the groove 2 is removed. It

Next, as shown in FIG. 3D, BPSG5 formed from the same raw material and having the same boron and phosphorus contents is deposited on the substrate surface. At this time, since the effective depth of the groove 2 is shallowed up to the previous step, almost no void is generated inside the groove 2. Moreover, even if it occurs, it becomes a very small void. After that, when heat treatment is performed at 900 to 1000 ° C., the voids are completely eliminated, and the inside of the groove 2 is completely filled with BPSG 3, 5.

After that, BP existing on the surface of the semiconductor substrate 1
By removing SG5 by etching, BPSG3,5 only in the groove 2
Is left, and the manufacturing of the insulating separation groove is completed.

Therefore, this manufacturing method is performed as shown in FIG.
When applied to the semiconductor substrate 11 having the densely concentrated grooves 12a and the sparse grooves 12b, the BPSG 13 is filled in all the grooves 12a, 12b under the same conditions by the steps of FIGS. 1 (a) to (d). As a result, the film thickness of the BPSG 15 formed on the surface of the semiconductor substrate 11 becomes substantially constant. However, in the dense groove 12a portion, the film thickness of that portion is somewhat thinned because the groove 12a is filled with a large amount.

Therefore, as shown in FIG. 2B, even if all the BPSG15 on the surface of the semiconductor substrate 11 is removed by etching in the subsequent step, the BPSG13, 15 are substantially evenly formed in any of the grooves 12a, 12b. It can be filled and the irregularities on the surface of the semiconductor substrate 11 can be made very small.

Although BPSG was used as the material for filling the groove in the above-described embodiment, it is also possible to perform insulation isolation by the groove in the same manner using boron / silicate glass, germanium / silicate glass or phosphorus / silicate glass. It is possible.

Although phosphine was used as an impurity raw material of phosphorus, an alcoholate containing phosphorus, for example, trimethyl phosphate (PO (OCH ₃ ) ₃ ) may be used instead of phosphine without any problem.

〔The invention's effect〕

As described above, the present invention removes voids in a state where the silicate glass is left only in the groove, and etches and removes the silicate glass of the semiconductor substrate after filling the silicate glass again. Since each groove is subjected to each process under the same condition, it is possible to uniformly fill all the grooves with silicate glass regardless of the difference in the density of the grooves of the semiconductor substrate. As a result, the surface of the semiconductor substrate can be flattened, the semiconductor device can be easily designed and manufactured, and the reliability and yield of the semiconductor device can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) to 1 (d) are vertical sectional views showing an embodiment of the present invention in the order of manufacturing steps, and FIGS. 2 (a) and 2 (b) are manufacturing methods of FIG. FIG. 3A is a vertical cross-sectional view showing an example of applying the method in the order of manufacturing steps, FIGS. 3A and 3B are vertical cross-sectional views showing the conventional manufacturing method in the order of steps, and FIGS. 4A and 4B are FIG. FIG. 6 is a vertical cross-sectional view showing an example in which the manufacturing method of is applied in the order of manufacturing steps. 1,11 …… Semiconductor substrate, 2,12a, 12b …… Groove, 3,13 …… BPS
G, 4,14 …… Void, 5,15 …… BPSG.

Claims (1)

[Claims] 1. A semiconductor substrate containing a groove, which is mainly composed of silicon oxide and contains impurities of groups 3 and 4 in a region including a groove.
Forming a silicate glass containing an element of any one of Group 5 and Group 5 or a combination thereof by a chemical vapor deposition method,
The step of etching away the silicate glass until the voids formed in the silicate glass in the groove are exposed, the step of performing heat treatment to once melt the silicate glass, and the same surface as the silicate glass Or a step of forming a silicate glass containing different impurities by a chemical vapor deposition method,
And a step of etching away the silicate glass on the semiconductor substrate.