JPS60211914A - Cvd apparatus - Google Patents

Abstract

PURPOSE:To attain the uniformity in reactions and in the thickness and characteristics of formed films by a system wherein gases supplied into a reaction unit can be controlled in sequence separately from one another and each gas is supplied intermittently with a time difference in which another gas can be diffused uniformly in the reaction unit. CONSTITUTION:After a heated state is attained, a sequence control unit 24 opens valves 21a and 21c, so that SiH4 gas and PH3 gas can be supplied from a gas supply port 14 into a reaction unit 12. When the valve 21a is closed after the SiH4 gas is supplied for a prescribed time, APC is also closed, and the SiH4 gas is diffused inside the reaction unit 12 to be uniform in density in a short time. Then, the sequence control unit 24 opens a valve 21b, so as to supply O2 gas. Thereby a chemical reaction is brought about, PSG is produced, deposited on and made to stick onto the surface of a wafer 13, and thus the formation of a film is completed. After the O2 gas is supplied for a prescribed time, the supply thereof is discontinued, so that the gas can be diffused and made uniform in the reaction unit 12. Then, the SiH4 gas is supplied again in the same way so as to react with the O2 gas. Thereafter, the processes described above are repeated. On said occasion, reactions are made to proceed in accordance with uniform quantities of gases.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to CVD (Chemical Vapor
The present invention relates to deposition technology, and in particular to CvD technology that can make the quality of deposited films uniform and improve step coverage.

[Background technology]

CVD film deposition technology used in the manufacture of semiconductor devices supplies a gas containing the elements of the substance to be generated together with a carrier gas, and causes chemical reactions such as thermal decomposition, oxidation, and reduction to occur on the substrate. By doing so, the desired substance is precipitated (Electronic Materials 1970 Extra Edition, Kogyo Kenkyukai, November 5, 1970, pages 61-67).

For example, a device schematically shown in FIG. 1 can be considered.

That is, a quartz tube 2 housing a semiconductor substrate (wah) 1
a reaction section 4 consisting of a heater 3 for heating the reaction gas, and a gas amount control section that sets the gas flow rates of different reaction gases A and H and supplies them into the reaction section 4 according to a signal from a gas sequencer 5. 6. An exhaust section 7 for exhausting the gas consumed in the reaction section 4 using a vacuum pump or the like, and the gas A;
It is comprised of an automatic pressure regulating valve (Arc) 8 that automatically opens and closes to keep the pressure within the reaction section 4 constant even when the amount of B changes.

Then, A according to the signal from the gas sequencer 5.

Each of the gases A and B is supplied into the reaction section 4, where the gases A and B are subjected to a chemical reaction under predetermined heating conditions, thereby depositing reaction products on the surface of the wave 1. Film formation will be performed.

However, in this configuration, since the gases A and B are supplied simultaneously and continuously into the reaction section 4, the supplied gases A and B reach the reaction section faster than they are diffused into the reaction section 4. The reaction between gases A and B tends to proceed from the 40 inlet side. For this reason, it becomes difficult for gases A and B to diffuse to the outlet side (exhaust side) of the reaction section 4, and as a result, the gas concentration in the reaction section 4 increases from the inlet side as shown in the gas concentration distribution in Figure 2 (3). This results in a distribution that has a slope toward the exit side. Therefore, the film formation rate (
(correlated with gas concentration), and each wafer 1
The inventors have found that it is difficult to form a film with a uniform thickness on the surface.

For this reason, heating control is performed using the heater 3 so that the temperature distribution within the reaction section 4 gradually increases from the inlet side to the outlet side as shown in ) in Fig. 2, and the film forming rate is controlled by the difference in gas concentration. It is possible to correct the variation by adjusting the reaction temperature conditions.

However, due to differences in reaction temperature, variations in impurity concentration and crystal size occur, resulting in uniform characteristics (
film quality) becomes difficult to form. In particular, the inventors have revealed that increasing the reaction temperature results in finer grains of crystals and lower step coverage of the film, making it difficult to perform fine buttering.

[Purpose of the invention]

The purpose of the present invention is to equalize the gas concentration within the reaction section, thereby achieving uniformity of film thickness and properties such as fineness of the film formed within the reaction section, thereby preventing variations in film quality. Our goal is to provide a CVD device that can.

The above and other objects and novel features of the present invention include:
It will become clear from the description of this specification and the accompanying drawings.

[Summary of the invention]

A brief overview of typical inventions disclosed in this application is as follows.

That is, by making it possible to independently sequence control the gases supplied into the reaction section, and by configuring each gas to be supplied intermittently with a time difference that allows other gases to be uniformly diffused within the reaction section. , the reaction within the reaction section is made uniform, the thickness of the film formed is made uniform and the characteristics are made uniform, thereby preventing variations in quality.

〔Example〕

FIG. 3 shows the CVD apparatus of the present invention in a semiconductor manufacturing apparatus, in particular a P
This is an example applied to an apparatus for manufacturing an SG (IJ silicate glass) film. In the figure, 10 is a quartz tube formed into a cylindrical shape, and together with a heater 11 disposed around it, constitutes a reaction section 12. This quartz tube 10 has one end open so that a semiconductor wafer 13, which is an object to be processed, can be taken in and out, and a lid 10a can be attached during processing.

Further, a gas supply port 14 is provided at this one end portion. On the other hand, an exhaust part 15 for evacuating the inside of the quartz tube 10 is connected to the other end of the quartz tube 10 by a vacuum pump (not shown), and an exhaust part 15 is connected to the other end of the quartz tube 10 to automatically open and close it in order to keep the gas pressure inside the quartz tube 10 constant. An automatic pressure control valve (APC) 16 is provided.

The gas supply port 14 has a pipe line 17 and a branch pipe line 17a.
, 17b, 17c through the SiH4 gas source 18.0. A gas source 19, PH, and a gas source 20 are connected. The branch pipes 17a, 17b, and 17c are provided with valves 21a, 21b, and 21C, respectively, and flow meters 22a,
22 b and 22 c, and a gas sequencer 23 is connected to these valves and flow meters to control the sequence control unit 24.
This sequence control unit 24 controls each pulp 2.
1a.

21b and 21c can be independently opened/closed or throttled.

Next, the operation of the CVD apparatus having the above configuration will be explained.

After placing the pulp 21 into the reaction section 12 to heat the entire reaction section 12, the sequence control section 24 controls the pulp 21.
a and 21c are opened, and SiH4 gas, PH, and gas are supplied into the reaction section 12 from the gas supply port 14. Note that SiH gas and 02 gas are directly related to the chemical reaction described later, and these two gases will be explained below. Figure 4 (5)
When the pulp 21a is closed after supplying SiH and gas for a certain period of time, the APC 1 that was open until then
'6 is also closed, and the SiH and gas are diffused into the reaction section 12 and are made to have a uniform concentration in a short time. After waiting for this, the sequence control section 24 opens the pulp 21b and supplies 02 gas into the reaction section 12 as shown in the same figure. This causes a chemical reaction between SiH4 gas and 02 gas, and P
SG is generated and deposited on the surface of the wafer 13, completing the film formation. After supplying the 02 gas for a certain period of time, the supply is stopped to allow the gas to diffuse into the reaction section 12 and become uniform.

Then, SiH4 gas is supplied again in the same manner as described above (the gas amount is approximately twice that of the previous time), and 0. React with gas to generate PSG again. By repeating this process as shown in (A) and (B) in the same figure, either the SiH4 gas or the 02 gas is always at a uniform concentration in the reaction section 12, and a uniform film is thereby formed. is possible.

That is, the reaction is only possible when both SiH, gas, or 02 gas are present, and therefore the reaction proceeds depending on the smaller amount of either gas. In this case, since the concentration of the gas supplied to the light is uniform, the reaction proceeds according to this uniform amount of gas, and it is said that a uniform reaction, that is, uniform film formation, is possible. be. Note that when looking inside the reaction section 12,
As shown in Figure 5, the 8iH gas that was supplied earlier moves to the exhaust side as the 02 gas is supplied, but the mixing area (reaction zone) for both gases is located in the middle, and the gases are reacting inside the reaction section. It can be seen that a uniform chemical reaction can be obtained due to the movement. The same holds true when 8iH4 gas is supplied again after 0□ gas.

As described above, it is possible to obtain a uniform reaction at any part in the length direction within the reaction section 12, and to make the thickness of the film formed uniform and the properties (film quality) uniform, thereby eliminating variations in film quality. prevention can be achieved.

〔effect〕

(1) A sequence control unit is provided in the gas supply system to the reaction section so that two or more different gases can be supplied independently, and there is a time difference in which the gases are made uniform within the reaction section after the - gas is supplied. Since the structure is configured such that other gases can be supplied at the same time, a uniform reaction can be carried out in any part of the reaction section, and a uniform film thickness can be achieved.

(2) Since the reaction is made uniform by equalizing the gas concentration within the reaction section, there is no need to create a temperature gradient within the two reaction sections, and film formation can be performed at a uniform temperature, resulting in uniform film quality. can be achieved.

(3) Since the gas (-) and other gases are alternately supplied to carry out a uniform reaction in a repeated state, it is possible to easily control film formation to a required thickness.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, SiH4 gas and NH as reaction gases.

Generation of silicon nitride film using gas or S
The same applies to the production of doped polysilicon films using iH4 gas and PH3 gas. Also in the case of the previous example, it is preferable to sequentially supply each gas of H4 gas, O21x, and PH3 gas.

[Application field]

In the above explanation, the invention made by the present inventor has mainly been explained in the case where it is applied to the field of application which is the background of the invention, which is a CVD apparatus for film formation of a conductor device, but the invention is not limited to this. CV for film deposition in other fields
It can also be applied as a D device. It can also be applied to plasma CVD equipment that uses plasma energy and heating as reaction energy, and atmospheric pressure CVD equipment that does not have an exhaust pump and does not create a low pressure inside the reaction section. It can also be applied to mold furnaces.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a CVD apparatus, Figure 2 (2) is a graph showing the distribution of gas concentration and temperature, Figure 3 is a configuration diagram of a CVD apparatus that is an embodiment of the present invention, and Figure 4 Fig. 5 is a graph showing a gas supply sequence for explaining an embodiment of the present invention, and Fig. 5 is a conceptual diagram showing a movement state of a reaction zone in a reaction section. DESCRIPTION OF SYMBOLS 10... Quartz tube, 11... Heater, 12... Reaction part, 13... Wafer, 14... Gas supply port, 15
...Exhaust section, 16...APC117...Pipeline, 1
8...SiH4 gas source, 19...02 gas source, 20
...PH3 gas source, 21a-21c...pulp, 2
3... Gas sequencer, 24... Sequence control section. Figure 1 Figure 2 Pyro

Claims (1)

[Scope of Claims] 1. A CVD apparatus that supplies two or more different gases into a reaction section and forms a film by reacting these gases, comprising:
A sequence control section is provided which can supply each of the above gases individually into the reaction section, and the sequence control section is arranged so that the - gas can be supplied into the reaction section with a time difference or means that allows the other gases to be uniformly diffused within the reaction section. A CVD apparatus characterized by having a configuration t7. 2. The CVD apparatus according to claim 1, wherein the sequence control section is configured to supply each gas alternately and intermittently. 3. The CVD apparatus according to claim 2, which is capable of supplying two types of gases alternately and with a predetermined time difference.