JPH11145127A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor device which can form an SiO2 film having a small dependency on an underlying substrate in deposition, an excellent step coverage, and a high insulation resistance value. SOLUTION: In a first deposition chamber 11 of a continuous CVD device 1, the flow rate of N2 gas which serves as a separator is rendered large so as to supply O3 gas and TEOS gas to a wafer W, in a state of comparatively avoiding mixing of the both, thereby forming a lower layer SiO2 film. In the adjoining second deposition chamber 12, the flow rate of the N2 gas, the separator, is rendered small so as to form an upper layer SiO2 film superposing on the lower SiO2 film of the wafer W in a state where O3 gas and the TEOS gas are comparatively mixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device using a continuous CVD apparatus.

[0002]

2. Description of the Related Art In an LSI manufacturing process, CVD (chemical vapor deposition) is used to deposit an insulating film for separating an element and a wiring and between a wiring and a passivation film for protecting the element from moisture and alkali metal. (Phase Deposition) technology is widely used, and the number of times of depositing an insulating film is also increasing with the adoption of multilayer wiring for increasing the density of LSI. Also,
At the same time, demands for CVD technology for improving step coverage and film characteristics are increasing.

Conventionally, a pure SiO ₂ film (NSG film) containing no P (phosphorus) or B (boron) as an insulating film is formed by CVD in which a monosilane (SiH ₄ ) gas and an O ₂ (oxygen) gas are reacted. In recent years, CVD using TEOS [tetraethoxysilane, (C ₂ H ₅ O) ₄ Si] gas and O ₃ (ozone) gas, which have excellent step coverage and are easy to handle, has been used in recent years. Is adopted. In addition, SiO ₂ containing P or B
The film (BPSG film) also has excellent step coverage and can be reflowed at a low temperature, so that TMB [trimethyl borate, (CH ₃ ) ₃ BO ₃ ], TMP [trimethyl phosphate, (CH ₃ ) _3] PO ₄ ]
CVD film formation using an OS gas and an O ₃ gas is performed.

[0004] If the steps and the undulations of the insulating film become large due to the increase in the number of wirings and the density of the wiring, the resolution of lithography will decrease and the film thickness will vary. Technology, and moisture taken in during the deposition of the insulating film degrades the corrosion of wiring, poor conduction, and degrades the characteristics of the transistor element to be formed. Therefore, a CVD technology that does not contain moisture in the insulating film as much as possible is required. Have been.

FIG. 1 is a side view schematically showing an example of a conventional continuous CVD apparatus 1. As shown in FIG. Referring to FIG. 1, wafer W is transferred into continuous CVD apparatus 1 by ascending belt 3 of transfer system 2 including endless belt (or mechanism for moving tray) 3. That is, the belt 3 is wound around a driving roll 4 and a driven roll 5, and is driven by a motor (not shown) so that the wafer W
Is transported from left to right in the continuous CVD apparatus 1 in FIG. A cleaning system 4 is provided in the middle of the descending belt 3, and the belt 3 is cleaned while passing through the cleaning system 4.

[0006] Immediately above the ascending belt 3, the first film forming chamber 11 and the second film forming chamber 1 are sequentially arranged from the upstream side.
2. A cooling chamber 13 is provided, and a gas is blown toward the wafer W transferred below. FIG. 2 is a schematic vertical sectional view showing the inside of the first film forming chamber 11 in a simplified manner. That is, on the bottom surface side of the first film forming chamber 11 directly above the ascending belt 3, N ₂ (as a separator) is provided on the upstream side and the downstream side with the TEOS gas blowing slit 31 disposed at the center therebetween. Nitrogen) gas blowing slits 32, and O ₃ gas blowing slits 3 upstream and downstream
3 are provided. Each slit is long in the width direction of the belt 3. A supply pipe 21 for supplying TEOS gas, a supply pipe 22 for supplying N ₂ gas, and a supply pipe 23 for supplying O ₃ gas are provided on the ceiling surface side of the first film forming chamber 11. After branching, a flat channel 21 defined by a plate for rectification
p, 22p, and 23p, and TEOS on the bottom side
Gas, N ₂ gas, O ₃ gas blowing slits 31, ₃
Gases 2 and 33 are respectively united to blow gas downward.

At the downstream side of the first film forming chamber 11, the second
The film forming chamber 12 and the cooling chamber 13 are arranged in series. Since the second film forming chamber 12 is configured in exactly the same manner as the first film forming chamber 11, its description is omitted. In the cooling chamber 13, O
_{The three} gases are blown toward the wafer W to cool the heated wafer W.

[0008]

There are the following two systems for mixing the TEOS gas and the O ₃ gas.

Post-mix system This is a system in which TEOS gas and O ₃ gas are mixed immediately before reaching the wafer W, and are separated by N ₂ gas until then. Although the SiO ₂ film formed by this method has little dependence on the underlayer, it has poor step coverage, and the film absorbs water generated during film formation and contains a large amount of water and has a low insulation resistance value. Pre-mix system This is a system in which TEOS gas and O ₃ gas are preliminarily mixed and supplied to the wafer W, and are often mixed in a pre-mix chamber (the pre-mix chamber is not shown in FIG. 2). The SiO ₂ film formed by this method has a large dependency on the underlayer, but has good step coverage, and has a lower water content and a higher insulation resistance value than the post-mix film.

In the above description, the dependence on the underlayer means that the growth rate of the SiO ₂ film formed thereon is influenced by the type of the underlayer or a trace amount of organic substances contained in the underlayer.

The conventional continuous CVD apparatus employs a post-mix system or a pre-mix system. When the underlayer dependence is small, the film characteristics are poor, and when the film characteristics are good, the underlayer dependence is low. It is not always satisfactory as a device used in the manufacture of large, high-density integrated semiconductor devices.

The present invention has been made in view of the above problems, and has low dependency on the underlayer at the time of film formation and good step coverage.
It is another object of the present invention to provide a method for manufacturing a semiconductor device capable of forming a SiO ₂ film having a high insulation resistance value.

[0013]

The above-mentioned object is achieved by the structure of claim 1. According to the solution, the method of manufacturing a semiconductor device according to the present invention is arranged in series toward the downstream side. A semiconductor device in which an ozone gas, an inert gas serving as a separator, and a TEOS gas are blown from above from the first gas blowout port and the second gas blowout port, respectively, and supplied to a wafer conveyed below to form a silicon oxide film. In the manufacturing method, the ozone gas and the TEOS gas are supplied to the wafer in a relatively non-mixed state at the first gas outlet, and the ozone gas and the TEOS gas are supplied in a relatively mixed state at the second gas outlet. Is the way.

By forming a film by such a method of manufacturing a semiconductor device, SiO ₂ having a low dependence on the underlayer at the time of film formation, a good step coverage, and a high insulation resistance is formed.
A film can be formed.

[0015]

As described above, according to the method of manufacturing a semiconductor device of the present invention, an O ₃ gas and a TEOS gas are first supplied from above to a wafer conveyed below without being relatively mixed. Then, the O ₃ gas and the TEOS gas are supplied in a relatively mixed state. However, when the O ₃ gas is used for mixing with the TEOS gas, the oxidizing power is larger than that of the O ₂ gas and the TEOS gas is used. This is because they are easy to react and the film formation rate can be increased.

As the inert gas used as the separator, any gas may be used as long as it does not hinder the formation of the SiO ₂ film, and N ₂ gas is usually used. Of course, Ar (argon) or He (helium) can also be used.

In order to supply O ₃ gas and TEOS gas to the wafer in a relatively non-mixed state at the first gas outlet and then to supply the wafer in a relatively mixed state at the second gas outlet, , An inert gas as a separator flowing between O ₃ gas and TEOS gas, for example, N 2
_This is achieved by making the flow rates of the _two gases large at the first gas outlet and small at the second gas outlet. In this case, for example, the arrangement of the gas blowing slits at the first gas blowing port is such that the O ₃ gas
The order of N ₂ gas and TEOS gas may be used.
The order of gas, N ₂ gas, and O ₃ gas may be used. Other preferred arrangements are O ₃ gas, N ₂ gas, TEOS gas, N ₂ gas.
In this arrangement, TEOS gas is placed at the center as gas / O ₃ gas.

Further, the O ₃ gas and the TEOS gas are mixed with the first gas.
In order to supply the wafer in a relatively non-mixed state at the gas outlet and then to supply the wafer in a relatively mixed state at the second gas outlet, other methods may be used, one of which is O ₃ In this method, the flow rates of the gas, the N ₂ gas, and the TEOS gas are constant, and the first gas outlet has a smaller distance from the wafer, and the second gas outlet has a larger distance with the wafer. Of course, both the adjustment of the gap between the gas outlet and the wafer and the adjustment of the flow rate of the N ₂ gas may be performed together.

In addition, the first gas outlet and the second gas outlet are kept in a first film forming chamber for keeping the temperature and for others.
It may be housed in the second film forming chamber. In general, a cooling chamber 13 for blowing O ₃ gas toward the wafer W is installed above the system for transporting the wafer and downstream of the second gas outlet, but of course, the cooling gas is May be N ₂ gas. The type of cooling gas is T
The gas used for the first gas outlet and the second gas outlet other than the EOS gas is reduced in the number of types of gas,
This is preferable in that the post-treatment of the gas does not become complicated. However, this does not limit the type of cooling gas.

Hereinafter, a method of manufacturing a semiconductor device according to the present invention will be described in detail with reference to an embodiment.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a method of manufacturing a semiconductor device according to the present invention, a device similar to a conventional continuous CVD device is basically used. Therefore, referring to FIGS. supplies separated flow large cities of the N ₂ gas by the flow control valve (not shown) is attached to the supply pipe 22 of the N ₂ gas, and O ₃ gas and the TEOS gas until just before it reaches the wafer W, Post on wafer W
Forming a lower SiO ₂ film of the mix method, followed in the second film forming chamber 12, also N ₂ gas small city the flow rate of N ₂ gas by the flow control valve (not shown) is attached to the supply pipe 22, O ₃ gas and TEOS
Supplying a mixture of gas previously, to form an upper SiO ₂ film of the pre-mix system to on the lower SiO ₂ film.

The film forming conditions described above are shown in Table 1.

[0023]

[Table 1]

Under the above film forming conditions, a lower SiO ₂ film having a low underlayer dependence is formed in the first film forming chamber 11, and the second film forming chamber 12 has good step coverage, small water content, and low insulation resistance. By forming a small upper SiO ₂ film, the dependence on the base is small as a whole,
A pure SiO ₂ film (NSG film) having good film characteristics was formed. Originally, a process using O ₃ gas and TEOS gas to form a pure SiO ₂ film is a process using SiO ₂ having good flatness.
₂ films are employed by the obtained is the most important deposition process in producing a semiconductor device of high integration density, pure S formed by the manufacturing method of the present invention
Since the iO ₂ film has higher flatness, the resolution is improved in lithography, and as a result, the spacing between wirings and a fine margin are obtained at values close to the design values, and the reliability of the manufactured semiconductor device is improved. I do.

The method of manufacturing a semiconductor device according to the embodiment of the present invention is structured and operates as described above. Of course, the present invention is not limited to these, and various methods based on the technical idea of the present invention are possible. Is possible.

For example, in the present embodiment, in the second film-forming chamber of the pre-mix system, the flow rate of the N ₂ gas as the separator is reduced to reduce the O ₃ gas.
Although a relatively mixed state was formed between the gas and the TEOS gas, the O ₃ gas and the TEOS gas were formed using a pre-mix chamber.
The gas and the gas may be mixed in advance.

In the present embodiment, the cooling chamber 13 is provided on the downstream side of the second film forming chamber 12, but the cooling chamber 13 can be omitted.

In this embodiment, the atmospheric pressure CVD
Although the case of manufacturing by forming an SiO ₂ film by the apparatus has been described, the method of the present invention is also applicable to the case of manufacturing an SiO ₂ film by a low pressure CVD apparatus.

In this embodiment, pure SiO ₂
Although the case of manufacturing a film has been described, the method of the present invention can also be applied to the case of manufacturing a SiO ₂ film doped with P or B.

In implementing the method of manufacturing a semiconductor device according to the present embodiment, a continuous CVD method suitable for the method of the present invention is used.
Although an apparatus may be manufactured, the first film forming chamber of a conventionally used continuous CVD apparatus of, for example, a pre-mix method is modified into a post-mix method, and the second film forming chamber is left as it is. Is also good.

[0031]

The present invention is embodied in the form described above, and has the following effects.

Pure Si using O ₃ gas and TEOS gas, which is the most important in manufacturing a semiconductor device with a high integration density
In the process of forming the O ₂ film, the underlayer dependency is small,
Since a pure SiO ₂ film having good step coverage and excellent flatness and excellent film characteristics is formed, wiring accuracy is high,
A semiconductor device with even higher reliability can be manufactured.

[Brief description of the drawings]

FIG. 1 is a side view schematically showing a continuous CVD apparatus.

FIG. 2 is a schematic sectional view of a first film forming chamber of the apparatus.

[Explanation of symbols]

1 ... continuous CVD apparatus, 3 ... belt, 11 ... first film forming chamber, 12 ... second film forming chamber, 13
...... cooling chamber, 21 ...... TEOS gas supply pipe, 21p ...... TEOS gas flat channel, 22 ...... N ₂
Gas supply pipe, 22p... N ₂ gas flat channel, 23
...... O ₃ gas supply pipe, 23p ...... O ₃ gas flat passage, 31 ...... TEOS gas blow slits, 32 ...... N
₂ gas blowing slits, 33 ...... O ₃ gas blow slits.

Claims (4)

[Claims] 1. An ozone gas, an inert gas as a separator, and a TEOS (tetraethoxysilane) gas, which are long in a direction substantially perpendicular to the transfer direction of each of an ozone gas, a separator, and a TEOS (tetraethoxysilane) gas provided above a wafer transferred below. Moving the slit toward the downstream side of the transport, the ozone gas, the inert gas, the TEOS gas, and the TEOS gas in this order.
OS gas, the inert gas, the ozone gas, or the first in the order of the ozone gas, the inert gas, the TEOS gas, the inert gas, and the ozone gas
A method for manufacturing a semiconductor device in which a silicon oxide film is formed by blowing each gas from a gas outlet and a similarly configured second gas outlet installed in series in the transport direction, wherein the first gas outlet is In the above, the ozone gas and the TEOS gas are supplied to the wafer in a relatively non-mixed state, and then the ozone gas and the TEOS gas are supplied to the wafer in a relatively mixed state at the second gas outlet. A method of manufacturing a semiconductor device. 2. A state in which the ozone gas and the TEOS gas are not relatively mixed in the first gas outlet is formed by setting a flow rate of the inert gas as a separator to be relatively large, and the second gas outlet is continued. 2. The method according to claim 1, wherein the state in which the ozone gas and the TEOS gas are relatively mixed in step (a) is formed with a relatively small flow rate of the inert gas as a separator. 3. A state in which the ozone gas and the TEOS gas in the first gas outlet are not relatively mixed with each other is formed such that a distance between a lower end of the first gas outlet and the wafer is relatively small. 2. The apparatus according to claim 1, wherein a state in which the ozone gas and the TEOS gas in the second gas outlet are relatively mixed is formed such that a distance between a lower end of the second gas outlet and the wafer is relatively large. 2. The method for manufacturing a semiconductor device according to item 1. A first gas outlet provided with the first gas outlet;
A cooling chamber is arranged in series on the downstream side of the film forming chamber and the second film forming chamber provided with the second gas outlet, and the ozone gas is blown toward the wafer as a cooling gas to cool the wafer. The method for manufacturing a semiconductor device according to claim 1, wherein: