JPH04237128A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enhance the reflowing property of a BPSG film for providing the film with a flat insulating film by a method wherein, the BPSG(boron phos phorus slicate glass film) is formed, oxygen plasma-processed and then heat- treated. CONSTITUTION:Wirings 3 comprising polycrystal silicon are formed on a silicon substrate 1 through the intermediary of an oxide film 2 and then a boron phosphorus silicate glass film (BPSG) 4 is formed on the whole surface by pressure- reduced vapor deposition step. Next, this silicon substrate 1 is mounted on a supporting electrode of a plasma device. Next, the whole surface is oxygen- plasma processed at reduced pressure so that the phophorus in the BPSG film 4 not sufficiently coupled with oxygen may be sufficiently coupled with oxygen. Next, the oxygen-plasma processed silicon substrate 1 is heat-treated in nitrogen atmosphere. Through these procedures, the reflowing property of the BPSG film 4 can be enhanced and thereby an insulating film of which flatness is importantly required in particular can be formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for forming an insulating film in which flatness is important.

0002

BACKGROUND OF THE INVENTION With the miniaturization of semiconductor devices, interlayer insulating films formed on the surfaces of polycrystalline silicon interconnects and metal interconnects are required to have even greater flatness. Currently, a boron phosphosilicate film (hereinafter referred to as BPSG film) is often used for this interlayer insulating film, and BPS is formed by heat treatment after forming the BPSG film.
A method is used in which the G film is reflowed to flatten its surface.

That is, as shown in FIG. 3, an oxide film 2 with a thickness of 200 nm is formed on a silicon substrate 1, and on top of the oxide film 2 is formed a width of 1.0 μm, a height of 400 nm, and a wiring interval of 1.0 μm.
A wiring 3 made of polycrystalline silicon is formed. Next, using tetraethoxysilane (TEOS), phosphine (PH3), trimethoxyboron (TMB) and oxygen as raw material gases, a BPSG film 4 of 400 nm in thickness was formed at a temperature of 620°C and a pressure of 0.4 Torr using a reduced pressure vapor phase growth method. Form. When this is heat-treated for 30 minutes in a nitrogen atmosphere at 900° C., the BPSG film 4 reflows and becomes flat. The angle α indicates the degree of reflow of the BPSG film 4, and in this conventional method, α is 22 degrees.

0004

[Problem to be solved by the invention] Phosphorus (
P) exists as P2 O5, which improves reflow properties in the subsequent heat treatment step. However, the conventional method described above has the problem that phosphorus that is not sufficiently bonded with oxygen remains in the BPSG film, which impairs reflow properties and causes phosphorus to precipitate on the surface after heat treatment.

[0005]

[Means for Solving the Problems] In the method of manufacturing a semiconductor device of the present invention, oxygen plasma treatment is performed after forming a BPSG film, and then heat treatment is performed.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. 1A and 1B are cross-sectional views of a semiconductor chip for explaining an embodiment of the present invention, and FIG. 2 is a configuration diagram of a parallel plate type plasma apparatus used in the embodiment.

First, as shown in FIG. 1(a), a wiring 3 made of polycrystalline silicon is formed on a silicon substrate 1 via an oxide film 2 with a thickness of 200 nm by the same operation as in the conventional method. Next, a B layer with a thickness of 400 nm was deposited on the entire surface by low pressure vapor phase epitaxy.
A PSG film 4 is formed. Next, this silicon substrate 1 is shown in FIG.
It is placed on the holding electrode 9 of the plasma device shown in FIG. Next, plasma is generated between the holding electrode 9 and the counter electrode 10 using the high frequency power source 8, oxygen is supplied into the reaction chamber 13 from the oxygen supply port 11, and oxygen plasma treatment is performed under reduced pressure using the exhaust system 12. , phosphorus which is not sufficiently combined as oxygen in the BPSG film is combined with oxygen.

Next, as shown in FIG. 1(b), the silicon substrate 1 which has been subjected to the oxygen plasma treatment in this manner is subjected to heat treatment in a nitrogen atmosphere at 900.degree. The angle α shown in the figure indicates the degree of reflow of the BPSG film, as in FIG.
In the method according to this example, α was 10 degrees. This shows that oxygen plasma treatment has a great effect on improving reflow properties.

[0009] In the above embodiment, a parallel plate type plasma apparatus is used for plasma processing, but it goes without saying that an external electrode type cylindrical plasma apparatus may also be used.

0010

[Effects of the Invention] As explained above, the present invention provides BPSG
By performing oxygen plasma treatment after film formation and then performing heat treatment, the reflow properties of the BPSG film can be improved, which has the effect that a semiconductor device having a flatter insulating film can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a semiconductor chip for explaining one embodiment of the present invention.

FIG. 2 is a configuration diagram of a plasma device used in an example of the present invention.

FIG. 3 is a cross-sectional view of a semiconductor chip for explaining a conventional method of manufacturing a semiconductor device.

[Explanation of symbols]

1 Silicon substrate 2 Oxide film 3 Wiring 4 BPSG film 8 High frequency power supply 9 Holding electrode 10 Counter electrode 11 Oxygen supply port 12 Exhaust system 13 Reaction chamber

Claims (1)

[Claims] 1. A method for manufacturing a semiconductor device, comprising the steps of forming a boronphosphosilicate film on a semiconductor substrate and then subjecting it to oxygen plasma treatment, and subjecting the semiconductor substrate to heat treatment.