JPH01169931A - Forming method for borophosphorosilicate glass film - Google Patents

Abstract

PURPOSE:To make the concentrations of boron and phosphorus uniform in a borophosphorosilicate glass(BPSG) film formed on a silicon wafer surface, by introducing B compound along the longitudinal direction of a reaction pipe in a dispersed manner, while separating it from P compound and Si compound. CONSTITUTION:A gas feeding pipe 11 extends in the longitudinal direction of a reaction pipe 1. The wall surface of the pipe is provided with many gas jetting holes in a domain of the reaction pipe 1 where a silicon wafer 3 is arranged. From the jetting holes, B compound gas 12 is spouted, while P compound gas is mixed with Si compound gas as usual, and introduced into the reaction pipe 1 through a gas feeding pipe 4. The irregularity of distributions of B concentration and P concentration in the longitudinal direction of the reaction pipe 1 is about + or -3%, which is improved as compared with the usual value of about + or -6%. Thus the concentrations of B and P in a BPSG film formed on a silicon wafer surface are made uniform.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a method for forming a BPSG (borophosphosilicate glass) film based on the CVD method.

We made a promise to make the composition of the BPSG film formed uniform within the reaction tube.

It has a long reaction tube in which a substrate to be processed is placed, and reacts gaseous boron compounds, phosphorus compounds, and silicon compounds introduced into the tube from one end in the lengthwise direction under reduced pressure. In an apparatus for producing a BPSG film on a surface of the substrate to be processed.

The method consists of separating the boron compound from the phosphorus compound and the silicon compound and introducing them in a distributed manner along the length of the reaction tube.

[Industrial application field]

The present invention relates to a method for forming a BPSG film used in the manufacture of semiconductor devices, and particularly to a method for forming an nPsG film based on a CVD (chemical vapor deposition) method.

[Conventional technology]

In semiconductor devices, a borophosphosilicate glass (IIPSG) film is used as an insulating layer between the eyebrows and the like. usually.

The BPSG film is formed by the CVD method, and a gaseous boron (B) compound, ! (1') A compound and a silicon (Si) compound are introduced, and BPSG, which is a reaction product of these compounds, is deposited on the surface of a substrate such as a silicon wafer placed inside this reaction tube.

Examples of the above gaseous compound include organic compound B(OCzHs)i (triethoxyborane) as shown below.

PO(OCI+3) 3 (trimethoxyphosphine oxide or trimethyl phosphate).

When using 5i(OCzlls)a (tetraethoxysilane), these compounds can be mixed in advance at a predetermined ratio and then introduced into the reaction tube.

[Problem that the invention seeks to solve]

FIG. 2 is a schematic cross-sectional view showing the general configuration of a conventional apparatus for forming an NR'SC film on the surface of a semiconductor substrate using the above-mentioned organic compound. For example, inside a reaction tube 1 made of transparent quartz, a silicon wafer 3 housed in a basket 2 made of quartz or the like is placed. Usually, several ten silicon wafers 3 are arranged so that each one stands upright. One end of the reaction tube 1 is closed by a lid 5 provided with a gas introduction tube 4;

The other end of the reaction tube 1 is closed by a second lid 7 provided with an exhaust pipe 6 connected to an exhaust system (not shown).

As described above, a gas in which P and Si organic compounds were mixed at a predetermined ratio was introduced into the reaction tube 1 from the gas introduction tube 4 of the apparatus shown in FIG.

Exhaust the air through the exhaust pipe 6 and maintain it at a predetermined pressure.

For example, the silicon wafer 3 is heated by an electric furnace 8 provided outside the reaction tube 1 . the result.

The introduced organic compound is thermally decomposed and reacts on the surface of the silicon wafer 3 to form a BPSG film.

A BPSG film is produced using the above-mentioned conventional apparatus.

As for the concentration of B and P in the BPSG film, as shown in FIG. 3, the closer to the gas introduction pipe 4, the higher the Btm concentration.

On the other hand, +P? :1 degree increases as the distance from the gas introduction tube 4 increases, and the range of variation reaches 1% to ±10% with respect to the predetermined composition of the nrsG film.

Generally, the softening temperature of a BPSG film varies depending on the B and P concentrations. Therefore, depending on the position of the silicon wafers 3 within the reaction tube 1, the thermal characteristics of the BPSG films formed on their surfaces vary.

As a result, the unevenness occurring on the surface of the silicon wafer 3 on which the semiconductor circuit is formed is removed by subsequent heat treatment (reflow treatment).
In the process, a problem arises in that the areas 41 flattened by the BPSG film are not equal.

Under appropriate conditions 9, for example within a limited P concentration range or within a production temperature range, it is possible to make the B and P concentrations uniform, but +I3? There are problems such as the M degree and P concentration cannot be selected to arbitrary values, and the production rate of the BPSG film is low.

The present invention does not depend on the position inside the reaction tube 1, but the silicon wafer 3
B and p fQ in the BPSG film produced on the surface
The purpose is to make the degree uniform.

[Means for solving problems]

The above object has a long reaction tube in which a substrate to be processed is disposed, and gaseous B compounds, P compounds and S are introduced under reduced pressure into the reaction tube from one end in the length direction.
In an apparatus that generates a BPSG film on the surface of a substrate to be processed by reacting an I compound, the B compound is separated from the P compound and the Si compound and introduced in a dispersed manner along the length direction of the reaction tube. This is achieved by the method for forming a BPSG film according to the present invention.

[For production]

A gas introduction tube that extends in the length direction of a long reaction tube and has a plurality of gas injection holes provided along the length, or a gas introduction tube that extends in the length direction of one reaction tube and has different lengths. Provided with multiple gas introductions.

By uniformly introducing the B compound gas into the reaction tube through the gas introduction tube, the B and p fQ degrees in the BPSG film formed on all silicon wafer surfaces can be made uniform.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, the same parts as in the existing drawings are designated by the same reference numerals.

FIG. 1 is a schematic cross-sectional view showing the general configuration of a B1'SG film production apparatus according to an embodiment of the present invention. In the illustrated apparatus, a gas introduction pipe 11 for introducing B compound gas is provided independently. The gas introduction tube 11 is made of quartz, for example, and may be mutually welded to the reaction tube 1 so as to pass through the reaction tube 1, which is also made of quartz, or may be made to pass through the lid 7 made of, for example, stainless steel. hand,
The lid 7 is sealed using a known quartz-to-metal sealing technique, or hermetically sealed using a Teflon joint.

The gas introduction tube 11 extends in the length direction of the reaction tube 1, and is provided with a large number of gas injection holes (not shown) on its wall surface at least in the area where the silicon wafer 3 is installed in the reaction tube 1. The B compound gas 12 is ejected from the ejection hole. on the other hand.

The P compound gas is mixed with the Si compound gas and introduced into the reaction tube 1 through the gas introduction tube 4 as in the conventional case.

Said B (OCJs) 1. PO (OCIh) 3. S
Organic compounds such as i (OC2H5) 4 are generally liquid at room temperature, and nitrogen (N2) or oxygen (0□) as a carrier gas is bubbled into these liquids to vaporize them, and the mixture is introduced into the reaction tube 1 together with the carrier gas. be introduced. An example of the Br'SG film formation conditions when using the above organic compound is as follows: the flow rate of each carrier gas is B(OCzHs)
11005CC for x.

400SCCM for PO(OCIh) 3, Si
(OCzlls) 400SCCM for 4, total pressure inside reaction tube 1 is 0.8 Torr, reaction temperature is 640°C
to 700°C.

Under these conditions, a BPSG film containing about 5% by weight of B and P is 6% by weight.
Generated at a rate of 0 people/min. The variation in the distribution of the BB degree and the PAW degree in the length direction of the reaction tube 1 is about 1 to 3%, which is significantly improved compared to the conventional value of about 6%. 2 to 6% by weight at 3 degrees of Br + 2 at 1 pBi degrees generated by changing the flow rate of the carrier gas mentioned above
Regarding the ~6% by weight BPSG film, the variation in BQQ degree and P concentration depending on the position inside one reaction tube 1 was improved in the same way as above.

Instead of the gas introduction pipe 11 provided with a plurality of gas ejection holes as shown in Fig. 1, the same effect can be obtained by providing a plurality of gas introduction pipes 13 of different lengths as shown in Fig. 4. can get. The apparatus of the embodiment shown in FIG. 4 is the same as the apparatus of the embodiment according to FIG. 1, except for the gas introduction pipe 13. Further, the sealing of the gas introduction tube 13 to the reaction tube 1 or the lid 7 is the same as in the previous embodiment.

Each gas introduction tube 13 is provided with a gas ejection hole (not shown) at or near the tip inside the reaction tube 1, and the B compound gas is mainly ejected into the reaction tube 1 from this gas ejection hole. For example, when three gas introduction pipes 13 are provided, the longest and shortest gas introduction pipes 13 have their respective tips.

The other gas introduction tube 13 is positioned near the silicon wafers at both ends of the large number of silicon wafers 3 arranged in the reaction tube 1, and the tip of the other gas introduction tube 13 is located near the silicon wafers at the intermediate position. Adjust the length of each so that it is located near 3.

It goes without saying that in the apparatuses of the above embodiments, the gas introduction pipe 11 or I3 may be sealed to the 1M section 5 so as to pass through the lid section 5.

〔Effect of the invention〕

According to the present invention, a gaseous organic compound is used to perform npsc.
When producing a film, B and P in the BPSG film
Distribution of concentration and position of the substrate inside the reaction tube.

Uniformity can be achieved regardless of the flow rate of the organic compound gas and the temperature at which the BPSG film is formed. As a result, the degree of freedom regarding the BPSG film formation conditions is increased, the npsc film having a desired composition can be formed at high speed, and the productivity in manufacturing semiconductor devices can be improved.

Schematic cross-sectional view.

FIG. 3 is a graph of B and PfH degree distribution in a BPSG film produced by a conventional apparatus.

FIG. 4 is a schematic sectional view showing the general configuration of an apparatus according to another embodiment of the present invention.

In fig.

1 is a reaction tube.

2 is a basket.

3 is silicon wafer.

4, 11 and 13 are gas introduction pipes.

5 and 7 are the lids.

6 is the exhaust pipe.

8 is an electric furnace.

12 is B compound gas.

It is.

Grass 1 diagram 2nd z Figure 4 One gas introduction required, including 6′ Uθ foot giant 1

Claims (3)

[Claims] (1) It has a long reaction tube in which a substrate to be processed is placed, and gaseous boron compounds, phosphorus compounds, and silicon compounds are introduced into the tube from one end in the longitudinal direction under reduced pressure. In an apparatus for forming a borophosphosilicate glass film on the surface of the substrate to be processed by reaction, the boron compound is separated from the glass phosphorus compound and the silicon compound and dispersed along the length direction of the reaction tube. 1. A method for forming a borophosphosilicate glass film, the method comprising: introducing a borophosphosilicate glass film; (2) extending in the length direction inside the reaction tube;
The method for forming a borophosphosilicate glass film according to claim 1, characterized in that a tube having a plurality of gas ejection holes is provided along the length direction. (3) A plurality of tubes having different lengths are provided inside the reaction tube, extending in the length direction and each having a gas injection hole at or near its tip. A method for forming a borophosphosilicate glass film according to item 1.