JPH0448732A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To restrain the roughening of the surface of a polysilicon and decrease the wiring short by the remains after etching or the scattering of wiring resistance by the roughness of the edge of wiring by specifying the concentration of the phosphorus, which is contained in a polysilicon film wherein phosphorus is diffused, below a specified value. CONSTITUTION:The surface of a silicon substrate 4 is thermally oxidated, and a thin silicon oxide film 3 is formed thereon, and then a polysilicon film is stacked by the chemical vapor growth method under decompression. Next, phosphorus glass is formed on the polysilicon film, and is heat-treated to diffuse phosphorus into the polysilicon film (phosphorus treatment). At this time, the concentration of phosphorus inside the polysilicon film is made 6X10<20>atm/cm<3> or less, and for the resistivity, 8X10<-4>OMEGA.cm can be gotten. For polysilicon wiring, the crystal particles are suppressed low, so there is no remains after etching nor roughening of wiring edge, thus favorable one can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device using multilayer wiring technology in which various thin films are stacked and manufactured, and in particular, a method for forming polysilicon wiring used as an electrode. It is related to.

[Conventional technology]

FIG. 2 shows a phosphorus-diffused polysilicon wiring formed by etching a phosphorus-diffused polysilicon film formed by conventional chemical vapor deposition under reduced pressure after photolithography. (a) is the plan view,
The same figure (b) similarly shows the sectional view.

In the figure, 1 is a polysilicon crystal grain, 2 is an etching residue, 3 is a silicon oxide film, and 4 is a silicon substrate.

The phosphorus-diffused polysilicon wiring shown in FIG. 2 is produced by first thermally oxidizing the surface of a silicon substrate 4 to form a thin silicon oxide film 3, and then depositing a polysilicon film by chemical vapor deposition under reduced pressure. .

Next, a phosphorus glass film is formed on the polysilicon film and heat treated to diffuse phosphorus into the polysilicon film (
(called phosphorus treatment).

At this time, the phosphorus concentration within the polysilicon film is 8X l
O” atm/cm!, and the resistivity is 7.5X10-
4Ω·cl is obtained. However, in order to increase the amount of phosphorus diffused within the polysilicon film in order to lower the wiring resistance,
Silicon crystals grow large during phosphorus treatment.

Thereafter, photolithography is performed and polysilicon wiring is formed by etching.

[Problem to be solved by the invention]

Conventional manufacturing methods are carried out as described above, so during etching after the photolithography process for forming polysilicon wiring, silicon crystal grains are large and remain unetched, resulting in short circuits with adjacent wiring, or crystal grains. The wiring edges are etched. Therefore, there is a problem in that the wiring resistance varies because the wiring width differs depending on the location of the wiring.

The present invention was made to solve the above-mentioned problems, and it reduces the size of the silicon crystal grains in the phosphorus-diffused polysilicon film, suppresses wiring shorts due to etching residue,
Alternatively, it is an attempt to eliminate variations in wiring resistance due to differences in wiring width.

[Means to solve the problem]

In the method for manufacturing a semiconductor device according to the present invention, the concentration of phosphorus contained in the phosphorus-diffused polysilicon film is reduced to 6×
IO" atm/cm3 or less.

[Effect]

In the present invention, since the phosphorus concentration in the polysilicon film into which phosphorus is diffused is defined to be 6×10” ate/cs+′ or less, roughness on the surface of the polysilicon film can be suppressed.

〔Example〕

Next, the present invention will be explained based on the embodiment shown in FIG.

1(a) and 1) are a schematic plan view and a sectional view thereof of a polysilicon wiring obtained by the manufacturing method of the present invention, and the same reference numerals in the figures indicate the same or corresponding parts.

In the method of this embodiment, first, the surface of a silicon substrate 4 is thermally oxidized to form a thin silicon oxide film 3, and then a polysilicon film is deposited by chemical vapor deposition under reduced pressure.

Next, a phosphorus glass film is formed on the polysilicon film, and heat treatment is performed to diffuse phosphorus into the polysilicon film (phosphorus treatment). At this time, the phosphorus concentration in the polysilicon film was treated with phosphorus to be less than 6 x 10 ''atm/cm'', and the resistivity was 8 x 10 -' Ω·clll. The amount of phosphorus diffused in the polysilicon film is increased by 6
10" Atm/c is less than 3, so the degree of silicon crystal growth during phosphorous treatment is reduced, resulting in small crystal grains. After that, photolithography is performed and polysilicon wiring in a predetermined pattern is formed by etching. can be formed.

In the polysilicon wiring formed in this way, the crystal grains are suppressed to a small size, as shown in Figure 1 (al and (b)), so there is no etching residue or rough wiring edges, and good quality can be obtained. It will be done.

In the above example, phosphorus treatment was performed after depositing the polysilicon film by chemical vapor deposition under reduced pressure. "A similar effect can be obtained by implanting less than atig/c1 and performing heat treatment.

Further, in the above example, a polysilicon film without phosphorus doping was deposited by chemical vapor deposition under reduced pressure, but instead, a polysilicon film doped with phosphorus to less than 6 X I O" ate/cm3 was deposited. Similar effects can be obtained by heat treatment.

〔Effect of the invention〕

As described above, according to the present invention, in the method for manufacturing the semiconductor device 1 using multilayer wiring technology in which various types of thin films are stacked, the phosphorus concentration contained in the phosphorus-diffused polysilicon film is reduced to 6X10t0ate. /cm3 or less, it is possible to suppress roughness on the surface of the polysilicon film. Therefore, when used as wiring, there is an effect that variations in wiring resistance due to wiring short circuits due to etching residues in post-processes or uneven wiring edges are reduced.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a plan view and a cross-sectional view of a semiconductor device according to an embodiment of the present invention when used as wiring on a silicon substrate, and FIGS. 2(a) and ('b) are FIG. 2 is a plan view and a cross-sectional view of a conventional semiconductor device used as wiring on a silicon substrate. 1... Polysilicon crystal grains, 2... Etching residue, 3... Silicon oxide film, 4... Silicon substrate. Agent Masuo Oishi 1 Ko (b) 1; Holi Silicon 4#&zuL 4: Silicon-4 Sheep (Fig. 2

Claims (1)

[Claims] In a method for manufacturing a semiconductor device using multilayer wiring technology in which various types of thin films are stacked, the phosphorus concentration contained in the phosphorus-diffused polysilicon film is set to 6×10^2.
A method for manufacturing a semiconductor device, characterized in that it is ^0 atm/cm^3 or less.