# US 5,702,673 A · Ozone generating apparatus

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- Number: US 5,702,673 A
- Document ID: US5702673A
- Status: Granted
- Kind: A
- Application number: 08/633,551
- Filed: 1996-04-17
- Granted: 1997-12-30
- Earliest claimed: 1995-04-17
- Assignees: Ebara Corporation; Kabushiki Kaisha Toshiba
- Inventors: Naruhiko Kaji; Yutaka Nakano; Rempei Nakata; Minoru Harada; Ryoichi Shinjo; Manabu Tsujimura
- Web page: https://patentgrep.com/patent/US5702673A

## CPC

- C01B 13/11: by electric discharge
- C01B 13/10: Preparation of ozone
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}

## Abstract

An ozone generating apparatus produces highly pure ozone gas which can be used in a semiconductor manufacturing process. The ozone generating apparatus comprises a high voltage source, an ozone generating cell which generates ozone gas by supplying a material gas while applying a high voltage from the high voltage source, and a passage for delivering the generated ozone gas from the ozone generating cell to a desired location. The passage comprises a material which has a passivation film formed by a passivation treatment in a dry process. The oxide passivation film comprises chromium oxide film, iron oxide film or a composite film of chromium oxide and iron oxide.

## Claims

### Claim 1

An ozone generating apparatus comprising:
a high voltage source;
an ozone generating cell which generates ozone gas by supplying a material gas comprising oxygen gas to which a small amount of nitrogen gas is added while applying a high voltage from said high voltage source; and
a passage for delivering the generated ozone gas from said ozone generating cell to a desired location, said passage comprising stainless steel having a passivation film comprising one of chromium oxide film, iron oxide film and a composite film of chromium oxide and iron oxide formed by a passivation treatment in a dry process.

### Claim 2 (depends on 1)

An ozone generating apparatus according to claim 1, wherein said stainless steel comprises electrolytically polished stainless steel.

### Claim 3 (depends on 2)

An ozone generating apparatus according to claim 2, wherein said passivation treatment is performed by baking said electrolytically polished stainless steel at a high temperature in an inert gas environment, and oxidizing the thus baked stainless steel with highly concentrated ozone gas.

### Claim 4 (depends on 2)

An ozone generating apparatus according to claim 2, wherein said passivation treatment is performed by baking said electrolytically polished stainless steel at a high temperature in an inert gas environment, and oxidizing the thus baked stainless steel with an oxidizing gas.