JPS61248519A - Chemical vapor deposition apparatus - Google Patents

Abstract

PURPOSE:To enable to increase the reactive gas feed while improving the mixed ratio thereof as well as the yield of elements by a method wherein, when a substrate to grow semiconductor layer etc. is arranged in a vapor growth apparatus and then a shower to jet material gas is provided above the substrate, the shower is provided with cooling tube. CONSTITUTION:A susceptor 3 with a built-in heater 5 is arranged in a chamber 1 with an exhaust duct 6 on the bottom to mount a processed substrate 4 growing a decomposed product on the substrate 3 while a shower 9 jetting material gas is provided on the opposing ceiling of chamber 1. In such a constitution, the shower 9 is screen-formed and a cooling tube 10 is wound around the shower 9 while leading tubes 7 to feed mixed gas containing material gas and carrier gas are provided on the surface of shower 9 and another decomposition accelerating tubes 11 are inserted into the periphery of shower 9. Through these procedures, the feed of mixed gas can be increased, simultaneously improving the mixed ratio of gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A chemical vapor deposition apparatus in which a shower for supplying a reaction gas into a chamber has a cylindrical shape to increase capacity, and a cooling pipe is provided to prevent reactions within the shower.

[Industrial application field]

The present invention relates to a chemical vapor deposition apparatus equipped with a shower that improves the concentration distribution of reaction gas and prevents reactions within the shower.

Chemical Vapor Depth
The CVD method (abbreviated hereafter as CVD) is a method of forming a desired thin film on a substrate using a gas phase reaction, and is used in the manufacturing process of semiconductor devices, including the epitaxial growth of semiconductors, as well as the growth of semiconductor layers, insulating layers, and conductor layers. widely used.

In other words, taking as an example the case where silicon (Si) is used as a semiconductor substrate, epitaxial growth is performed using silicon chloride (Si).
SiC1m ) or dichlorosilane (Si112
The growth of polysilicon (polySt) is carried out by reducing a mixture of C12) and 112 at a high temperature of 1000 to 1200°C, and the growth of polysilicon (polySt) is achieved by a thermal decomposition reaction between SiHa and 112 at a relatively low temperature of 600°C or higher. It is carried out by

Also, insulators such as silicon oxide (SiO2) are
4, nitrous oxide (No), and H2 mixed gas at 700
The conductor layer is formed by thermally decomposing tungsten fluoride (WFs) or tungsten chloride (WCIg) at a temperature of 400°C or higher to form a thin layer on the substrate. This is then selectively etched using photolithography to create various patterns to form semiconductor elements.

The characteristics of CVD growth are that various gases and mixed gases can be used as reaction gases, and that films can be formed with good step coverage. It is necessary to grow it.

[Conventional technology]

Fig. 2 shows the configuration of a conventional CVD apparatus. Inside a chamber 1 connected to an exhaust system, there is a shabu 2 at the top for spouting a reaction gas, and a susceptor 3 is installed opposite to the shabu 2. A substrate 4 to be processed is placed thereon.

Here, the susceptor 3 is configured to include a heating source 5 therein, and by heating the susceptor by supplying electricity to the heater, the substrate 4 to be processed can be maintained at a desired temperature.

Further, an exhaust duct 6 is provided on the device board on which the susceptor 3 is provided, and is connected to an exhaust system consisting of a mechanical booster, a rotary pump, and the like.

The following describes the case of forming a thin layer of aluminum (AI) on the substrate 4 to be processed made of silicon (Si) using CVD.
The law is explained as follows.

While the exhaust system is operated to exhaust the inside of the chamber 1, a reaction gas is supplied into the chamber 1 from the shower 2, and 0.
The degree of vacuum is maintained at about 3 to 0.5 Torr.

Although not shown, the inlet pipe 7 of the shower 2 is equipped with a source gas pipe, a carrier gas pipe 9, an catalytic gas pipe, and the like, each equipped with a flow meter to accurately measure the flow rate. A mixed gas is created by adjusting the

In this example, triisobutylaluminum (Al(CH2Cl(CH))2) is used as the source gas, argon (Ar) is used as the carrier gas, and hydrogen (++z) is used as the decomposition promoting gas. The reaction gas is composed of

These gases reach the shower 2 through the introduction pipe 7 in a mixed state, and a number of jet holes 8 are provided on the lower surface of the shower 2.
It is ejected more toward the substrate 4 to be processed.

However, the distance between the shower 2 and the substrate 4 to be processed is 30~
On the other hand, since the substrate 4 to be processed is maintained at 300° C. in this embodiment, the temperature of the shower 2 has increased, and a decomposition reaction is likely to occur inside the shower.

Also, since the mixed gas is supplied to the shower 2 which has a smaller volume than the introduction pipe 7, after it spreads inside the shower,
It is not easy to eject water at a uniform flow rate from a large number of pores, and it is not easy to set the conditions because the position of the ejection holes 8, the hole diameter, etc. have a large effect.

On the other hand, in order to increase the mass production effect, the size of the substrate 4 to be processed is 4.
As the size increases from an inch diameter to a 5 inch diameter, and from a 5 inch diameter to a 6 inch diameter, and as the flow rate of the reaction gas increases, uniform CVD growth on the substrate 4 to be processed becomes difficult.
When the thickness of the substrate in the center of the substrate is less than that, CVD growth occurs and unreacted products tend to remain, and an improvement has been desired.

[Problem that the invention seeks to solve]

As explained above, when forming a semiconductor layer, an insulating layer, a conductor layer, etc. on a substrate to be processed using a CVD growth apparatus,
The problem is that CVD growth becomes non-uniform as the size of the substrate to be processed increases and the amount of reactant gas supplied increases.Another problem is that the source gas tends to condense due to reactions in the shower. be.

[Means for solving problems]

The above problem involves a shower that spouts a reaction gas into a chamber connected to an exhaust system, and a susceptor that faces the shower and is equipped with a heating source, and a substrate to be processed is placed on the susceptor and heated. In the apparatus for thermally decomposing the reaction gas to grow decomposition products on the substrate to be processed, the shower has a cylindrical shape to increase the internal volume and is provided with cooling pipes on the entire surface. This problem can be solved using a vapor phase growth apparatus.

[Effect]

The present invention improves mixing of reaction gases by increasing the volume of the shower, moderates the flow velocity from the introduction pipe, and eliminates reactions within the shower by providing a cooling pipe in the shower to suppress temperature rise. be.

That is, in order to eject the reaction gas at an even flow rate from the ejection holes 8 provided on the bottom surface of the shower, the position and size of the ejection holes 8 were conventionally adjusted. By expanding the volume of the shower 9, the introduction pipe 7
The flow rate of the reactant gas supplied is moderated to prevent this flow rate from directly affecting the ejection holes 8.

Furthermore, gases that easily react with the source gas, such as decomposition-promoting gases, are supplied into the shower 9 separately from the conventional introduction pipe 7 to prevent condensation reactions from occurring within the introduction pipe 7. By providing a cooling pipe 10 for cooling, decomposition within the shower 9 can be eliminated.

〔Example〕

FIG. 1 shows the structure of a CVD apparatus embodying the present invention, which is the same as the conventional one except for the structure of the shower 9.

That is, the shower 9 according to the present invention has a cooling pipe 10 around it.
It is provided in a cylindrical shape with a decomposition promoting gas pipe 1.
1 is provided separately from the introduction pipe 7 and configured to mix with the source gas and carrier gas inside the shower 9.

In addition, a cooling pipe 10 is provided along the surface of the shower 9 for water cooling, thereby suppressing a temperature rise due to radiant heat from the substrate 4 to be processed and the susceptor 3.

In this way you can use a 6 inch diameter shower to create a 4 inch diameter shower.
As a result of growing A1 by CVD on the substrate 4 to be processed consisting of an inch-sized Si wafer, the variation in film thickness was within 5%,
Also, the analysis results showed that no undecomposed substances were found in the center of the substrate to be processed, unlike in the conventional case.

〔Effect of the invention〕

As mentioned above, with conventional CVD equipment, as the area of the substrate to be processed increases and the amount of reactant gas supplied increases, it becomes difficult to achieve uniform growth, but by implementing the present invention, uniform growth is now possible. , the yield of semi-thick body elements can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a CVD apparatus according to the present invention, and FIG. 2 is a sectional view of a conventional CVD apparatus. In the figure, 1 is a chamber, 2.9 is a shower, 3 is a susceptor, 4 is a substrate to be processed, 5 is a heat source,
7 is an introduction pipe, 8 is an ejection hole, 10 is a cooling pipe, and 11 is a decomposition promoting gas pipe.

Claims (1)

[Claims] In the chamber (1) connected to the exhaust system, there is a shower (9) for spouting a reaction gas, and a susceptor (3) equipped with a heating source (5) facing the shower (9). In the growth apparatus, the substrate to be processed (4) is placed on the substrate to be processed (4) and heated, and the reaction gas is thermally decomposed to grow a decomposition product on the substrate to be processed (4).
) is provided with a cooling pipe (10).