# US 5,348,898 A · Semiconductor device and method for manufacturing the same

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- Number: US 5,348,898 A
- Document ID: US5348898A
- Status: Granted
- Kind: A
- Application number: 08/009,061
- Filed: 1993-01-26
- Granted: 1994-09-20
- Earliest claimed: 1979-05-25
- Assignees: Hitachi, Ltd.
- Inventors: Yuji Yatsuda; Takaaki Hagiwara; Ryuji Kondo; Shinichi Minami; Yokichi Itoh
- Web page: https://patentgrep.com/patent/US5348898A

## CPC

- G11C 16/0466: {comprising cells with charge storage in an insulating layer, e.g. metal-nitride-oxide-silicon [MNOS], silicon-oxide-nitride-oxide-silicon [SONOS] (G11C16/0483, G11C16/0491 take precedence)}
- H10B 69/00: Erasable-and-programmable ROM [EPROM] devices not provided for in groups H10B41/00 - H10B63/00, e.g. ultraviolet erasable-and-programmable ROM [UVEPROM] devices
- G11C: STATIC STORES (semiconductor memory devices H10B)
- H10B: ELECTRONIC MEMORY DEVICES

## Abstract

The present invention deals with a semiconductor memory circuit device, in which a memory array portion of a rectangular shape consisting of semiconductor non-volatile memory elements is formed on a main surface of the semiconductor substrate, a low voltage driver circuit (decoder) is formed along a side of the memory array portion, and a high voltage driver circuit is formed along an opposite side of the memory array portion. This permits a reduction in word line length and avoids crossing of the word lines to permit increased operation speed and, particularly, increased reading speed.

## Claims

### Claim 1

A method of manufacturing semiconductor devices at a major surface of a semiconductor substrate, comprising:
(a) locally forming a first mask layer on said major surface of said semiconductor substrate;
(b) introducing impurities of a first type of conductivity into said major surface of said semiconductor substrate not covered with said first mask layer, in a self-aligned manner with said first mask layer, in order to form a first semiconductor region of said first type of conductivity;
(c) oxidizing said major surface of said semiconductor substrate not covered with said first mask layer, so as to form an oxide film in a self-aligned manner with said first mask layer;
(d) introducing impurities of a second type of conductivity into said major surface of said semiconductor substrate not covered with said oxide film, in a self-aligned manner with said oxide film, in order to form a second semiconductor region;
(e) locally forming a second mask layer on said first semiconductor region;
(f) introducing impurities of said first type of conductivity into said first semiconductor region not covered with said second mask layer, in a self-aligned manner with said second mask layer;
(g) oxidizing said major surface of said semiconductor substrate not covered with said second mask layer, so as to form a field insulating film in a self-aligned manner with said second mask layer;
(h) forming a gate electrode on said first semiconductor region; and
(i) introducing impurities of said second type of conductivity into said first semiconductor region, in order to form a source or a drain region in a self-aligned manner with said gate electrode and said field insulating film.

### Claim 2 (depends on 1)

A method of manufacturing semiconductor devices according to claim 1, further comprising a step, before step (a), of forming an oxide film on said major surface of said semiconductor substrate, said oxide film being thinner than said field insulating film.

### Claim 3 (depends on 1)

A method of manufacturing semiconductor devices according to claim 1, wherein said first mask layer comprises a silicon nitride film and a photoresist film formed on said silicon nitride film, with step (b) being performed using said silicon nitride film and said photoresist film as a mask.

### Claim 4 (depends on 3)

A method of manufacturing semiconductor devices according to claim 3, wherein said step (c) is performed by using said silicon nitride film as a mask.

### Claim 5 (depends on 4)

A method of manufacturing semiconductor devices according to claim 4, further comprising a step, before step (d), of removing said silicon nitride film.

### Claim 6 (depends on 1)

A method of manufacturing semiconductor devices according to claim 1, wherein said second mask layer comprises a silicon nitride layer and a photoresist film formed on said silicon nitride layer.

### Claim 7 (depends on 6)

A method of manufacturing semiconductor devices according to claim 6, wherein said step (f) is performed by using said silicon nitride film and said photoresist film as a mask.

### Claim 8 (depends on 7)

A method of manufacturing semiconductor devices according to claim 7, further comprising a step, before step (g), of removing the photoresist film.

### Claim 9

A method of manufacturing semiconductor devices at a major surface of a semiconductor substrate, comprising:
(a) forming a first oxide film on said major surface of said semiconductor substrate;
(b) forming an anti-oxidation film on said first oxide film;
(c) locally forming a first mask layer on said anti-oxidation film;
(d) etching said anti-oxidation film by using said first mask layer as a mask, so as to form a patterned anti-oxidation film;
(e) introducing impurities of a first type of conductivity into said major surface of said semiconductor substrate not covered with said first mask layer in a self-aligned manner with said first mask layer in order to form a first semiconductor region of said first type of conductivity;
(f) oxidizing said major surface of said semiconductor substrate not covered with said anti-oxidation film, so as to form a second oxide film in a self-aligned manner with said patterned anti-oxidation film;
(g) introducing impurities of a second type of conductivity into said major surface of said semiconductor substrate not covered with said second oxide film in a self-aligned manner with said second oxide film in order to form a second semiconductor region;
(h) forming a further anti-oxidation film on said major surface of said semiconductor substrate;
(i) locally forming a second mask layer on said further anti-oxidation film so as to expose a part of said major surface of said semiconductor substrate on said first and second semiconductor regions;
(j) etching said further anti-oxidation film using said second mask layer as a mask, so as to form an etched further anti-oxidation film;
(k) introducing impurities into said semiconductor substrate not covered with said etched further anti-oxidation film in a self-aligned manner with said second mask layer;
(l) oxidizing said major surface of said semiconductor substrate in a self-aligned manner with said etched further anti-oxidation film, in order to form a field insulating film on said major surface of said semiconductor substrate not covered with said etched further anti-oxidation film;
(m) removing said etched further anti-oxidation film;
(n) forming a gate electrode on said first semiconductor region; and
(o) introducing impurities of said second type of conductivity into said first semiconductor region, in order form a source or a drain region in a self-aligned manner with said gate electrode and said field insulating film.

### Claim 10 (depends on 9)

A method of manufacturing semiconductor devices according to claim 9, wherein each of said anti-oxidation film and further anti-oxidation film comprises a silicon nitride film.

### Claim 11 (depends on 9)

A method of manufacturing semiconductor devices according to claim 9, further comprising a step, before step (1), of removing said second mask layer.

### Claim 12

A method of manufacturing semiconductor devices at a major surface of a semiconductor substrate, comprising the steps of:
(a) forming an anti-oxidation film on said major surface of the semiconductor substrate;
(b) covering said anti-oxidation film with a photoresist mask to cover a portion of said anti-oxidation film overlying a first selected surface area of said major surface, and to leave another portion of said anti-oxidation film, overlying a second selected surface area of said major surface, not covered by said photoresist mask;
(c) introducing impurities of a first conductivity type into said second selected surface area thereby to form a first semiconductor region of said first conductivity type at said second selected surface area;
(d) subjecting and semiconductor substrate, which is covered by said portion of said anti-oxidation film but not covered by said another portion of said anti-oxidation film, said another portion having been removed by etching away said another portion of said anti-oxidation film not covered by said photoresist mask, to an oxidation treatment, thereby to form an oxide film at said second selected surface area;
(e) introducing impurities of a second type of conductivity, opposite to said first conductivity type, into said first selected surface area using said oxide film as a mask, thereby to form a second semiconductor region of said second conductivity type at said first selected surface area;
(f) forming a further anti-oxidation film on said major surface of said semiconductor substrate;
(g) locally forming a second mask layer on said further anti-oxidation film so as to expose a part of said major surface of said semiconductor substrate on said first and second semiconductor regions;
(h) etching said further anti-oxidation film using said second mask layer as a mask, so as to form an etched further anti-oxidation film;
(i) introducing impurities into said main surface of said semiconductor substrate in a self-aligned manner with said second mask layer;
(j) forming a field insulating film on said major surface of said semiconductor substrate not covered with said etched further anti-oxidation film, in a self-aligned manner with said etched further anti-oxidation film;
(k) forming a gate electrode on said first semiconductor region; and
(l) introducing impurities of said second conductivity type into said first semiconductor region, in order to form a source or a drain region in a self-aligned manner with said gate electrode and said field insulating film.

### Claim 13 (depends on 12)

A method of manufacturing semiconductor devices according to claim 12, wherein each of said anti-oxidation film and further anti-oxidation film comprises a silicon nitride film.

### Claim 14 (depends on 13)

A method of manufacturing semiconductor devices according to claim 13, further comprising a step, before step (j), of removing said second mask layer.