JPH03218905A - Ozonizer and insulating film forming device using the ozonizer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ozone generator and an insulating film forming apparatus using the same, and particularly to an ozone generator that can stably supply ozone at a sufficiently high concentration. The present invention also relates to an insulating film forming apparatus that can form an insulating film with excellent film quality and step coverage by using the apparatus.

[Conventional technology]

FIG. 8 is a partially cutaway configuration diagram showing a conventional ozone generator. Oxygen gas 02 is supplied from an oxygen gas supply tube 2 to a cylindrical discharge tube 1 . An electrode 3 is arranged at the center of the discharge tube 1, and this electrode 3 is used to absorb zero oxygen gas introduced into the discharge tube 1. It has the function of exciting ozone and supplying energy for ozone generation. The discharge tube 1 to which the oxygen gas supply tube 2 is connected is in communication with the adjacent discharge tube 4, and the discharge tube 4 is connected to an ozone discharge tube 5 that discharges generated ozone 03. Since the discharge tubes 1 and 4 become hot,
The surrounding area is cooled by the cooling water in the cooling water storage container 6. This cooling water storage container 6 is grounded, and a cooling water introduction pipe 7 and a cooling water discharge pipe 8 for introducing and discharging cooling water are provided at the bottom thereof, respectively.

The conventional ozone generator is configured as described above, and silent discharge is performed by the discharge tubes 1 and 4 into which oxygen gas 02 is introduced and the electrode 3. This silent discharge causes zero oxygen gas.
2 is excited and generates ozone 03. Ozone generated 0
3 is discharged from the ozone discharge pipe 5 together with unreacted oxygen 02.

In the ozone generator as described above, it has been found that the process of generating ozone 03 is carried out by the following reaction equations (1) and (2).

* Here e is energy O is oxygen radical 2 be.

In addition, in the above-mentioned ozone generator, for example, when high-purity oxygen gas for semiconductor manufacturing (purity of 99.95% or more, the same applies hereinafter) is used as the raw material gas, ordinary oxygen cylinder gas (purity of less than 99.95%) is used as the raw material gas. There is a fact that the ozone generation efficiency is significantly reduced compared to the case where the ozone is used. Based on this fact, the above-mentioned formula (1).
In addition to equation (2), it is generally believed that the process of ozone generation is also carried out by the reaction shown in equation (3).

0+O +M→030M...(3)2 Here, M is a substance that acts as a catalyst. In other words, the ozone generation efficiency is higher when oxygen cylinder gas is used as the raw material gas than when the high-purity oxygen gas mentioned above is used as the raw material gas, so other substances contained in the oxygen cylinder gas are used as catalysts. It is thought that it is working.

On the other hand, when oxygen cylinder gas is used as the raw material gas, relatively high concentration ozone 03 can be generated, but the ozone generation efficiency differs depending on the purity of oxygen gas 02 contained in the oxygen cylinder gas.

FIG. 9 is a schematic diagram of a conventional insulating film forming apparatus using an ozone generator. This apparatus forms an insulating film on a substrate by atmospheric pressure CVD by reacting ozone generated by the conventional ozone generator (indicated by symbol X in FIG. 9) with an organic source gas. This device has 1
989 VLSI MOLTI LEVEL INTER
CONNECTION CONPERENCE (IEE
This is what is described in Fig. 1, page 386 of the Proceedings (Sponsored). The general configuration of this device will be described below.

10 is a chamber section for forming an interlayer insulating film, 12
is a gas supply system that supplies raw material gas.

? The chamber part 10 consists of a dispersion head 15 having a slit-shaped gas outlet and a susceptor 18 on which a wafer 17 can be mounted and heated by the heater 6. The gas supply system 12 includes a bubbler 13 that generates tetraethoxysilane gas (hereinafter referred to as TEOS gas) and an ozone generator 14 that supplies ozone.
It consists of an ozone generator X having the same configuration as that shown in FIG.

Using the insulating film forming apparatus configured as described above, the wafer 1
When forming an interlayer insulating film on 7, oxygen gas 02 is introduced into the ozone generator 14, and a mixed gas (0/0) of ozone 03 and oxygen 02 is generated by silent discharge as described above. In addition, TEOS, which is a typical silicon alcoholate, is gasified by introducing nitrogen gas N2 into the bubbler 13 placed in a thermostatic chamber at around 360°C and bubbling it. Mixed gas with (TE
OS/N2). Then, the 03/02 mixed gas and the TEOS/N2 mixed gas are mixed and introduced into the chamber part 10 as a raw material gas. The raw material gas introduced into the chamber part 10 is passed from the dispersion head 15 having a slit-like flow path to the susceptor 18 with its surface facing downward.
The wafer 1 is mounted on the wafer 1 and heated by the heater 6.
7. A silicon oxide film, which will become an interlayer insulating film, is then deposited on the surface of the wafer 17 by atmospheric pressure CVD. Note that during film formation, the wafer 17 is rocked in the direction of arrow B in order to improve the uniformity of the film thickness. Thereafter, the source gas is exhausted in the direction of arrow A. It is known that the silicon oxide film formed as described above has better film quality and step coverage as the ozone concentration increases.

[Problem to be solved by the invention]

Conventional ozone generators are configured as described above.
Ozone generation efficiency is low when high-purity oxygen gas is used as raw material gas. On the other hand, when oxygen cylinder gas is used as the raw material gas, ozone O2 at a relatively high concentration can be obtained, but there is a problem in that the efficiency of ozone generation changes as the purity of the oxygen gas O2 changes.

In addition, in conventional insulating film forming equipment using an ozone generator, the ozone generation efficiency is low when the conventional ozone generator uses high-purity oxygen gas as the raw material gas, as described above. There was a problem that the film quality and step coverage were not excellent. On the other hand, if oxygen cylinder gas is used as the raw material gas, a conventional ozone generator can produce ozone at a relatively high concentration, but the quality is not stable as mentioned above, and the concentration is not high enough. There was a problem in that it was not possible to obtain satisfactory film quality and step coverage of the silicon oxide film.

This invention was made to solve the above-mentioned problems, and includes an ozone generator that can stably generate ozone at a sufficiently high concentration, and an ozone generator that can improve film quality and step coverage. An object of the present invention is to obtain an insulating film forming apparatus that can form an excellent insulating film.

[Means to solve the problem]

An ozone generator according to the present invention uses oxygen gas as a raw material and generates ozone 03 by subjecting the oxygen gas to a predetermined process, and is provided with a nitrogen gas supply means for mixing nitrogen gas into the oxygen gas. It is characterized by:

The mixing ratio of oxygen gas and nitrogen gas by the nitrogen gas supply means is set to 1. Nitrogen gas-1: 0.0002~
It may be set to 0.02.

An insulating film forming apparatus according to the present invention includes an ozone generator configured as described above, a gas generator that generates a gas containing alcoholate, a gas generated from the gas generator, and ozone generated from the ozone generator. React C
The reactor is equipped with a reaction device for depositing an insulating film on a base layer using a VD method.

[Effect]

In the ozone generator according to the present invention, a nitrogen gas mixing means for mixing nitrogen gas into oxygen gas is provided, and the oxygen gas mixed with nitrogen gas is subjected to a predetermined process for ozone generation. Highly concentrated ozone can be generated by the action of nitrogen gas.

The mixing ratio of oxygen gas and nitrogen gas is oxygen gas: nitrogen gas -
1: 0.002 to 0.02, high concentration ozone can be obtained and ozone generation efficiency is stabilized.

Since the insulating film forming apparatus according to the present invention is equipped with the ozone generator having the above configuration that can generate high concentration ozone,
The film quality and step coverage of the insulating film formed on the base layer are improved.

〔Example〕

FIG. 1 is a partially cutaway configuration diagram showing an embodiment of an ozone generator according to the present invention. The difference from the conventional apparatus shown in FIG. 8 is that a nitrogen gas supply means 100 is newly provided. Nitrogen gas N2 is supplied into the discharge tube 1 from the nitrogen gas supply means 100 via the nitrogen gas supply pipe 9. Other configurations are the same as before.

Next, the operation will be explained. High-purity oxygen gas 02 is supplied from the oxygen gas supply pipe 2, and nitrogen gas N2 is supplied to the circular discharge tube 1 from the nitrogen gas supply means 100 via the nitrogen gas supply pipe 9.
electrodes 3 each introduced into the discharge tube 1 and placed in the center of the discharge tube 1
Is there a silent discharge? It will be done. Figure 2 shows high purity oxygen gas 0
It is a graph showing the relationship between the mixing ratio of nitrogen gas N2 to (1) and the ozone concentration generated. The horizontal axis shows the mixing ratio of nitrogen gas N2 to high-purity oxygen gas as a value converted to standard conditions (0°C, 1 atm), and the vertical axis shows the generated ozone concentration as a value also converted to standard conditions. ing. Also,
The white circles are the measurement results when nitrogen gas is mixed, the black circles are the measurement results when only high-purity oxygen gas is used, and the one-dot chain line is the measurement results when high-purity oxygen gas 02 is mixed with argon.

From this graph, for example, if 0.02% of high-purity oxygen gas 023ofI, that is, only 6 cc of nitrogen gas N2 is added, the ozone concentration increases approximately six times compared to the case without addition, and high-purity oxygen Nitrogen gas N for gas 02
It can be seen that the ozone concentration is low when the mixing ratio is 0.02X 10 -2 or less.

-2 Also, the mixing ratio of nitrogen gas N2 is 0.02X 1 0
With the above, ozone of 100 g/Nrrl' or more can be stably generated, especially 0. IX 1 0-2~1
．． It can be seen that in the range of 7×10 −2 , ozone of about 120 g/Nrf can be stably generated.

Furthermore, it can be seen that the ozone concentration generated gradually decreases when the mixing ratio of nitrogen gas N2 to high purity oxygen gas 02 exceeds 0.33×10−2. Furthermore, if the mixing ratio of nitrogen gas N2 becomes too large, nitrogen oxides may be generated, which is not preferable. Taking these things into consideration, the mixing ratio of nitrogen gas N2-2 to high purity oxygen gas 02 should be 0.02X 10 to 2. Ox 1 0
It has been found that a value of −2 is desirable, and this allows highly concentrated and stable ozone to be supplied.

Note that when argon gas is mixed with high-purity oxygen gas 02 instead of nitrogen gas N2, the ozone concentration generated is approximately 20 g/Nd regardless of the amount of argon mixed. The ozone generation rate did not change even when mixed with

From this experimental result, the prediction that nitrogen gas N2 functions as the catalyst M shown in equation (3) is reliable.

On the other hand, when oxygen cylinder gas is used instead of high-purity oxygen gas, it has been experimentally confirmed that when nitrogen gas N2 is mixed, the ozone concentration increases, although not as much as when high-purity oxygen gas is used. It has also been confirmed that the shape of the graph showing the relationship between the mixing ratio of cylinder gas and nitrogen gas and the ozone concentration generated is similar to the graph in FIG. 2.

As described above, by using the ozone generator according to the present invention, it is possible to generate ozone with a higher concentration.

In addition, although the case where ozone is produced|generated by silent discharge was demonstrated in the said Example, this invention is applicable to all the ozone generation apparatuses which use oxygen gas as a raw material.

FIG. 3 is a schematic diagram showing an embodiment of an insulating film forming apparatus according to the present invention, which utilizes the above-mentioned ozone generator (indicated by symbol Y in FIG. 3). In other words, a new nitrogen gas supply means 100 is added to the insulating film forming apparatus shown in FIG.
has been established. Other configurations are the same as before. The operation is also the same as before.

By using the ozone generator according to the present invention, high-concentration ozone can be stably supplied as described above.
The film quality and step coverage of the silicon oxide film can be improved. This is illustrated using FIGS. 4 to 7.

FIGS. 4 to 7 are diagrams showing that film quality and step coverage change depending on changes in ozone concentration.

FIG. 4 is a diagram showing the relationship between the ozone concentration and the etching rate of a silicon oxide film, where white circles indicate the case where silicon oxide films are simply stacked, and black circles indicate the case where annealing was performed at 450° C. for 30 minutes. It can be seen that in both cases, the etching rate decreases as the ozone concentration increases.

FIG. 5 is a diagram showing the relationship between ozone concentration and film shrinkage rate of a silicon oxide film. Note that the silicon oxide film in this case is
Annealing was performed at 450° C. for 30 minutes. It can be seen that the membrane shrinkage rate decreases as the ozone concentration increases.

FIG. 6 is a diagram showing the relationship between ozone concentration and leakage current of a silicon oxide film. The white circles indicate the case where silicon oxide films were simply laminated, and the black circles indicate the case where annealing was performed at 450° C. for 30 minutes. It can be seen that in both cases, the leakage current decreases as the ozone concentration increases.

As described above, when the ozone concentration is increased, the etching rate, film shrinkage rate, and leakage current are reduced. Therefore, the film quality becomes denser due to the high concentration of ozone, and a silicon oxide film with excellent crack resistance and insulation properties can be obtained.

FIG. 7 is a diagram showing the ozone concentration and the step coverage of the silicon oxide film. It can be seen that when a relatively high concentration of ozone is used (dotted line), the surface shape is flatter and the step coverage is better than when a relatively low concentration of ozone is used (solid line).

As described above, by using highly concentrated ozone, it is possible to form a silicon oxide film with excellent film quality (etching rate, film shrinkage rate, rectification current) and step coverage.

Although the silicon oxide film was formed by normal pressure CVD in the above embodiment, the same effect can be obtained by low pressure CVD.

Further, in the above embodiment, a case was explained in which a silicon oxide film was formed using a silicon-based alcoholate, but in addition to silicon-based alcoholates, alcoholates containing boron or phosphorus, such as triethylborate (TEB), trimethylphosphate (TMPO), etc. It is thought that the same effect can be obtained by using high concentration ozone even when forming a boron phosphorus glass (BPSG) film by simultaneously using it as a raw material gas.

〔Effect of the invention〕

As described above, according to the ozone generator according to claim 1,
Since the nitrogen gas supply means for mixing nitrogen gas into oxygen gas is provided, there is an effect that highly concentrated ozone can be generated.

Moreover, according to the ozone generator according to claim 2, a nitrogen gas supply means for mixing nitrogen gas into oxygen gas is provided, and the mixing ratio of oxygen gas and nitrogen gas is adjusted to 1:0.0002 to 0.0002.
02, it is possible to obtain ozone at a high concentration, and the ozone generation efficiency can be stabilized at a high value.

Furthermore, according to the insulating film forming apparatus according to claim 3, since the ozone generator according to claim 1 which generates high concentration ozone is used, the film quality and step coverage of the insulating film formed on the base layer are improved. This has the effect of improving.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway configuration diagram showing an embodiment of the ozone generator according to the present invention, FIG. 2 is a graph for explaining the operation of the device shown in FIG. 1, and FIG. A schematic diagram showing the configuration of an insulating film forming apparatus using such an ozone generator, FIGS. 4 to 7 are diagrams for explaining the operation of the apparatus shown in FIG. 3, and FIG. 8 is a diagram showing a conventional ozone generator. FIG. 9 is a partially cutaway configuration diagram showing the apparatus, and FIG. 9 is a schematic diagram showing the configuration of a conventional insulating film forming apparatus. In the figure, 1 and 4 are discharge tubes, 2 is an oxygen gas supply tube,
3 is an electrode, 5 is an ozone discharge pipe, 6 is a cooling water storage container, 7
8 is a cooling water inlet pipe, 8 is a cooling water discharge pipe, 9 is a nitrogen gas supply pipe, 100 is a nitrogen gas supply means, and Y is an ozone generator. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (3)

[Claims] (1) An ozone generator that uses oxygen gas as a raw material and generates ozone by subjecting the oxygen gas to a predetermined process, the ozone generator comprising a nitrogen gas supply means for mixing nitrogen gas into the oxygen gas. Generator. (2) In an ozone generator that uses oxygen gas as a raw material and generates ozone by subjecting the oxygen gas to a predetermined process, a nitrogen gas supply means for mixing nitrogen gas into the oxygen gas is provided, and the oxygen gas and the An ozone generator characterized in that the mixing ratio of oxygen gas to nitrogen gas is 1:0.0002 to 0.02. (3) An insulating film forming apparatus for forming an insulating film on a base layer, comprising: the ozone generator according to claim 1; a gas generator that generates a gas containing alcoholate; and a gas generator that generates a gas containing alcoholate. An insulating film forming apparatus using an ozone generator, comprising a reaction device that causes a gas to react with ozone generated from the ozone generator and deposits the insulating film on the base layer by a CVD method.