Method of manufacturing a semiconductor device having a plurality of elements

• US 5,019,526 A
• Filed: 09/26/1988
• Issued: 05/28/1991
• Est. Priority Date: 09/26/1988
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Yamane, Hiroyuki, Fujii, Tetsuo, Higuchi, Yasushi
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): WILCZEWSKI, MARY A
• Application Number:
  US07/249,514
• Time in Patent Office: 974 Days
• Field of Search: 437/24, 437/37, 437/69, 437/70, 437/228, 437/238, 156/662, 156/663, 156/628, 148/DIG. 117, 148/DIG. 118
• US Class Current: 438/440
• CPC Class Codes: H01L 21/31111 by chemical means
• CPC Class Codes: H01L 21/76213 introducing electrical inactive or active impurities in the local oxidation region, e.g. to alter LOCOS oxide growth characteristics or for additional isolation purpose
• CPC Class Codes: H01L 21/76216 introducing electrical active impurities in the local oxidation region for the sole purpose of creating channel stoppers
• CPC Class Codes: Y10S 148/117 Oxidation, selective
• CPC Class Codes: Y10S 438/911 Differential oxidation and etching

Abstract

A method of manufacturing a semiconductor apparatus having a plurality of elements formed on a substrate comprises forming a pad oxidized film on the surface of the semiconductor substrate, forming a pattern of silicon nitride film to coat device areas on the pad oxidized film, and injecting boron ions into that surface of the pad oxidized film where no silicon nitride film is present, thereby to form a channel stopper region. Using the pattern of the silicon nitride film as a mask, a heat oxidized film is then formed on an elements separating region by heat oxidization, and ions of Si, N, C, or the like are injected into the surface of the heat oxidized film with such an acceleration energy that the ions are not injected into the silicon nitride film thereby to change the quality of the heat oxidized film. The silicon nitride film is removed by etching and the heat oxidized film is etching-treated by a solution of the hydrofluoric acid group to etching-remove particularly the bird'"'"'s beak portions each of which is present along and under the peripheral rim of an element area of the silicon nitride film.

Claims

1. A method of manufacturing a semiconductor device having a semiconductor substrate and a plurality of elements formed on the substrate, said method comprising the steps of:

oxidizing the entire surface of the semiconductor substrate, thereby forming a pad oxide film thereon;

forming a pattern of silicon nitride film on those parts of the pad oxide film where the elements will be formed;

forming a heat oxide film on those parts of the pad oxide film which are exposed;

injecting ions selected from the group consisting of Si, N and C into the surface of the heat oxide film with such an acceleration energy that the ions do not pass through the silicon nitride film, thereby to change the quality of the heat oxide film to form a reformed layer;

removing the pattern of silicon nitride film by means of a first etching process; and

etching a part of the heat oxide film, excluding the region where the reformed layer has been formed, by a second etching process using an acid solution.

2. The method according to claim 1, whereby ions of Si are injected into the surface of the heat oxide film, in the process of forming the reformed layer.

3. The method according to claim 1, whereby ions of N are injected into the surface of the heat oxide film, in the process of forming the reformed layer.

4. The method according to claim 1, whereby ions of C are injected into the surface of the heat oxide film, in the process of forming the reformed layer.

5. The method according to claim 1, whereby a plurality of bird'"'"'s beak portions of the heat oxide film are formed, each of said portions entering along and under the peripheral rim of an element area of silicon nitride film, in the process of forming the heat oxide film, and no reformed layer is formed on the surface of the bird'"'"'s beak portions.

6. The method according to claim 1, whereby a plurality of bird'"'"'s beak portions of the heat oxide film are formed, each of said portions entering along and under the peripheral rim of an element area of silicon nitride film, in the process of forming the heat oxide film, and the bird'"'"'s beak portions on which no reformed layer is formed are selectively etched in the second etching process.

7. The method according to claim 1, further comprising injecting boron ions, using the pattern of silicon nitride film as a mask, to form P⁺ °

type channel stopper region at that part of the semiconductor substrate where no silicon nitride film is present.

8. A method of manufacturing a semiconductor device having a semiconductor substrate and a plurality of elements formed on the substrate, said method comprising the steps of:

oxidizing the entire surface of the semiconductor substrate, thereby forming a pad oxide film thereon;

forming a pattern of silicon nitride film on those parts of the pad oxide film where the elements will be formed;

forming a heat oxide film on those parts of the pad oxide film which are exposed;

injecting ions selected from the group consisting of Si, N and C into the surface of the heat oxide film with such an acceleration energy that the ions do not pass through the silicon nitride film, thereby forming a reformed layer having a quality which is changed such that, when the heat oxide film is etched with use of an etchant, an etching rate of the region where the ions have been injected becomes smaller than the etching rate of the region where the ions have not been injected;

removing the pattern of the silicon nitride film by means of a first etching process; and

etching a part of the heat oxide film with use of said etchant, excluding the part where the reformed layer has been formed, by means of a second etching process.

9. The method according to claim 8, whereby a plurality of bird'"'"'s beak portions of the heat oxide film are formed, each of said portions entering along and under a peripheral rim of an element area of silicon nitride film, in the process of forming the heat oxide film, and no reformed layer is formed in the surface of the bird'"'"'s beak portions.

10. The method according to claim 8, whereby a plurality of bird'"'"'s beak portions of the heat oxide film are formed, each of said portions entering along and under the peripheral rim of an element area of silicon nitride film, in the process of forming the heat oxide film, and the bird'"'"'s beak portions on which no reformed layer is formed are selectively etched in said etching process.

11. The method according to claim 8, further comprising injecting boron ions using the pattern of silicon nitride film as a mask, to form a P⁺ type channel stopper region at that part of the semiconductor substrate where no silicon nitride film is present.