JPH03228332A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To make it possible to form an insulating film having a superior buried flatness and to contrive to improve the yield of the manufacture of an integrated circuit device because the insulating film having the superior flatness can be formed by a process only of one time by a method wherein a deposited film in a fluid state is vapor-phase grown on the main surface of a semiconductor substrate at a substrate temperature equal to an higher than the glass transition temperature of the deposited film. CONSTITUTION:In the manufacturing process of a semiconductor device, wherein a deposited film 204 is formed for flattening a step of the main surface of a semiconductor substrate, the film 204 in a fluid state is vapor-phase grown on the main surface of the substrate using a substrate temperature of the glass transition temperature or higher of the film 204. For example, an insulating film 202 is formed on a single crystal silicon substrate 201 with an semiconductor element formed thereon and moreover, polycrystalline silicon wirings 203 are formed. Then, a vapor growth of a fluid BPSG film 204 is performed at a substrate temperature of 900 deg.C, at a pressure of 0.6 Torr, at the flow rate of 120SCCM of SiH4 gas, at the flow rate of 2 slm of N2O gas, at the flow rate of 10SCCM of PH3 gas and the flow rate of 10SCCM of B2H6 gas. Thereby, the formed film 204 becomes one having a flatness superior that of a conventional film obtainable by performing two processes of film formation and reflow.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a vapor phase growth method for flattening steps that occur in a semiconductor device manufacturing process using an insulating film.

[Conventional technology]

Conventional techniques for flattening steps on the main surface that occur during the manufacturing of semiconductor devices include PSG (phosphorus glass) and BPS.
An insulating film such as G (borophosphorus glass) is formed by a vapor phase growth method, and then the temperature (
950°C or higher for PSG film, 850°C for BPSG film
There is a method of performing heat treatment using the above method and reflowing.

[Problem to be solved by the invention]

In the conventional planarization technique described above, reflow is performed after the insulating film is deposited, so the flatness after reflow largely depends on the step coverage during the insulating film deposition. In particular, when the steps are closely spaced as in ultrahigh-integration circuits and the ratio of step height to step distance (aspect ratio) approaches 1.0, the steps become smaller as the film grows during the insulating film deposition process. As the aspect ratio becomes larger and larger, it becomes difficult for the reactant gas to enter the bottom of this step. As a result, voids are generated,
This void does not disappear even after reflow. Furthermore, if the step has an overhang shape, voids will occur even if, for example, a vapor phase growth method with 100% step coverage is used. The occurrence of such voids has the drawback of significantly deteriorating device characteristics, resulting in a decrease in device yield and reliability. Even in places where the steps are wide apart, the conventional method cannot achieve sufficient flatness, resulting in a large difference in height between the insulating film on the step and the insulating film at the bottom of the step, resulting in disconnections in the wiring formed on top of the insulating film. or a short circuit may occur.

Further, in the conventional planarization technique, there is a problem that the phosphorus or boron concentration changes due to changes in the film over time after the film is deposited, and therefore the reflow shape after reflow is not stable. Furthermore, conventional planarization techniques have the disadvantage that the film deposition process using the vapor phase growth method and the heat treatment process for the flow are separated, which increases the number of processes and lowers the yield of integrated circuit devices.

[Means to solve the problem]

The present invention provides a method for manufacturing a semiconductor device in which a deposited film is formed in order to flatten a step on the main plane of a semiconductor substrate, in which the deposited film is deposited in a fluid state on the main surface of the semiconductor substrate at a substrate temperature higher than the glass transition temperature of the deposited film. The film is grown in a vapor phase. Note that the vapor pressure of the fluid deposited film needs to be lower than the pressure of the source gas.

〔Example〕

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

FIG. 1 is a schematic diagram of an apparatus for depositing a BPSG film using a furnace tube type reduced pressure vapor phase growth apparatus according to a first embodiment of the present invention. 101 is a semiconductor substrate, 102 is a reactor, 103
is a heater, and 108 is a flow controller. Silane (SiH4) gas, H20 gas, PH3 gas, 82H6
The gases are S i Ha gas supply pipe 104 and N20, respectively.
Gas supply pipe 105, PH3 gas supply pipe 106, B2H6
The gas is introduced from the gas supply pipe 107. Thereby, a BPSG film can be formed on the semiconductor substrate.

FIG. 2 is a process-order cross-sectional view of a semiconductor device in which a BPSG film is formed using the apparatus shown in FIG. 1 of the present invention. An insulating film 20 is formed on a single crystal silicon substrate 201 on which a semiconductor element is formed.
A polycrystalline silicon wiring 203 is further formed by etching (FIG. 2(a)). Next, vapor phase growth of a fluid BPSG film, which is a feature of the present invention, is performed using the apparatus shown in FIG. Film forming conditions are substrate temperature 900℃, pressure 0
, □Torr, S i H4 gas flow rate 120 SCCM
.

N20 gas flow rate: 251m, PH3 gas flow rate 10! Ic
cM, B2 H6 gas flow rate is 105 CCM. The BPSG film being formed under these conditions has fluidity and excellent step coverage. FIG. 2(b) is a cross-sectional view during formation of a fluid BPSG film, in which approximately 2000 films were formed on a flat area. Note that the vapor pressure of the BPSG film is about 0, ITOrr. When a fluid BPSG film is used in this manner, the step coverage is excellent from the initial stage of film formation, and no overhang shape is formed at the step portion, so it is possible to embed even a wiring interval of 1 μm or less. In this way, liquidity B
After forming the PSG film to a desired thickness (FIG. 2(C)), the introduction of gas is stopped. Next, the gas in the reactor is replaced and the pressure is returned to atmospheric pressure, and the semiconductor substrate is pulled out from the reactor. At that time, the BPSG on the semiconductor substrate is cooled by the outside air.
The film becomes a solid state insulating film. Its shape is fluidity B
The state in which the PSG film is formed (Fig. 2 (C)) is maintained.The BPSG film formed in this way has better flatness than the conventional film that requires two processes: film formation and reflow. , the reliability and manufacturing yield of semiconductor devices are greatly improved.

FIG. 3 is a schematic diagram of an apparatus for depositing a BPSG film using a distributed atmospheric pressure vapor deposition apparatus according to a second embodiment of the present invention. 301 is a reaction chamber, 302 is a semiconductor substrate, 303 is an exhaust pipe, and 304 is a substrate support stand. Board support stand 304
The semiconductor substrate 302 placed on the substrate is heated to 870° C. by an infrared lamp 305. Silane gas, PH3 gas,
B2H6 gas is SiH4 gas supply pipe 311゜P.
H3 gas supply pipe 310. B2H6 gas is introduced from the supply pipe 309, mixed in advance, and then transferred to the disk version head 3.
Send to 06. In addition, N2o gas is supplied via the N20 gas supply pipe 308.
into the dispersion head 306. These gases react on a semiconductor substrate heated to 870°C,
Form BPS GM in a fluid state. After forming the desired film thickness, the substrate is cooled by stopping the gas supply and turning off the infrared lamp 305, and the BPSG film becomes an insulating film in its conventional state. The BPSG film formed using this method also has excellent flatness, similar to the first embodiment.

In this example, [S i H4 + N20 + PH3 + B2H6] system was used as the gas system for depositing the BPSG film, but other gas systems such as 5i (OC2H4) 4
In other words, it can be similarly implemented using TEOS or the like. Further, in this embodiment, the deposited film is a BPSG film, but any insulating film having a glass transition temperature in the range of 400°C to 1000°C may be used.

〔Effect of the invention〕

As explained above, the present invention achieves an insulating film with excellent embedded flatness by vapor-phase growing a fluid deposited film on the main surface of a semiconductor substrate at a substrate temperature higher than the glass transition temperature of the deposited film. It has the effect of forming a film. Furthermore, since an insulating film with excellent flatness can be formed in only - times of steps, the manufacturing yield of integrated circuit devices is improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus in a first embodiment of the present invention using a low pressure vapor phase growth method, and FIGS. 2(a) to (c) are manufacturing steps of a semiconductor device using the first embodiment. The sectional view and FIG. 3 are schematic diagrams of an apparatus in which atmospheric pressure vapor phase growth is used in a second embodiment of the present invention. 101.302...Semiconductor substrate, 102...Reactor, 103...Heater 104.31!・-・SiH
4 gas supply pipe, 105,308...N20 gas supply pipe, 106,310...PH3 gas supply pipe, 107.3
09...B2H6 gas supply pipe, 108°312...
Flow rate controller, 201... silicon substrate, 202
... Insulating film, 203 ... Polycrystalline silicon wiring, 20
4... Fluid BPSG membrane, 301... Reaction chamber, 30
3... Exhaust pipe, 304... Board support stand, 3゜5...
- Infrared lamp, 306...disversion head, 307...quartz glass.

Claims (1)

[Claims] 1. In the manufacturing process of a semiconductor device in which a deposited film is formed to flatten a step on the main surface of a semiconductor substrate, a substrate temperature higher than the glass transition temperature of the deposited film is applied on the main surface of the semiconductor substrate. 1. A method for manufacturing a semiconductor device, characterized by vapor phase growth of a deposited film in a fluid state. 2. The method of manufacturing a semiconductor device according to claim 1, wherein in the vapor phase growth of the fluid deposited film, the vapor pressure of the fluid deposited film material is lower than the pressure of the film forming raw material gas.