# US 5,707,898 A · Method of forming a programmable non-volatile memory cell by providing a shielding layer over the gate sidewalls

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- Number: US 5,707,898 A
- Document ID: US5707898A
- Status: Granted
- Kind: A
- Application number: 08/627,778
- Filed: 1996-04-01
- Granted: 1998-01-13
- Earliest claimed: 1996-04-01
- Assignees: Micron Technology, Inc.
- Inventors: J. Dennis Keller; Roger R. Lee
- Web page: https://patentgrep.com/patent/US5707898A

## CPC

- H10W 42/20: protecting against electromagnetic or particle radiation, e.g. light, X-rays, gamma-rays or electrons
- H10D 30/0411: {of FETs having floating gates}
- H10D 30/6891: {characterised by the shapes, relative sizes or dispositions of the floating gate electrode}
- H10W 42/00: Arrangements for protection of devices (arrangements for thermal protection H10W40/00)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A method of reducing undesired electron depletion through sidewalls of a floating gate of a floating gate transistor comprising providing a non-oxide or oxynitride layer over said sidewalls. Integrated circuitry including a non-volatile field effect transistor includes, a) a floating gate transistor having a gate construction and a pair of opposing source/drain regions, the gate construction having at least one sidewall; b) a shielding layer over the gate sidewall; and c) a dielectric layer on the shielding layer, the dielectric layer being of a different material than the shielding layer. The shielding layer might be provided over an oxide layer previously provided on sidewalls of the gate construction. The shielding layer might be provided over sidewall spacers previously provided relative to sidewalls of the gate construction. Example and preferred shielding layer materials include Si.sub.3 N.sub.4, oxynitride compounds, and aluminum.

## Claims

### Claim 1

A method of forming a floating gate transistor, comprising:
forming a floating gate construction having opposing lateral sidewalls;
providing opposing source and drain regions operably adjacent the floating gate construction;
forming an oxide layer over the gate sidewalls;
forming a shielding layer over the oxide layer;
forming sidewall spacers over the shielding layer and outwardly of the sidewalls; and
forming a dielectric layer over the sidewall spacers, the dielectric layer being of a material different than the shielding layer.

### Claim 2 (depends on 1)

A method as claimed in claim 1, wherein the shielding layer comprises a non-oxide material.

### Claim 3 (depends on 1)

A method as claimed in claim 1, wherein the shielding layer comprises Si.sub.3 N.sub.4 having a thickness of from about 50 Angstroms to about 200 Angstroms.

### Claim 4 (depends on 1)

A method as claimed in claim 1, wherein the shielding layer comprises aluminum.

### Claim 5 (depends on 1)

A method as claimed in claim 1, wherein the dielectric layer is selected from the group which comprises BPSG and undoped SiO.sub.2.

### Claim 6

A method of forming a floating gate transistor, comprising:
forming a floating gate construction having opposing lateral sidewalls;
providing opposing source and drain regions operably adjacent the floating gate construction;
forming an oxide layer over the gate sidewalls;
forming sidewall spacers over the oxide layer and outwardly of the gate sidewalls;
forming a shielding layer over the sidewall spacers; and
forming a dielectric layer over the shielding layer, the dielectric layer being of a different material than the shielding layer.

### Claim 7 (depends on 6)

A method as claimed in claim 6, wherein the shielding layer comprises a non-oxide material.

### Claim 8 (depends on 6)

A method as claimed in claim 6, wherein the shielding layer comprises Si.sub.3 N.sub.4 having a thickness of from about 50 Angstroms to about 200 Angstroms.

### Claim 9 (depends on 6)

A method as claimed in claim 6, wherein the shielding layer comprises aluminum.

### Claim 10 (depends on 6)

A method as claimed in claim 6, wherein the dielectric layer is selected from the group which comprises BPSG and undoped SiO.sub.2.

### Claim 11

A method of forming a floating gate transistor, comprising:
forming a floating gate construction having opposing lateral sidewalls;
providing opposing source and drain regions operably adjacent the floating gate construction;
forming an oxide layer over the gate sidewalls;
forming a shielding layer over the oxide layer, the shielding layer comprising Si.sub.3 N.sub.4 having a thickness of about 50 Angstroms to about 200 Angstroms;
forming sidewall spacers over the shielding layer and outwardly of the sidewalls; and
forming a dielectric layer over the sidewall spacers, the dielectric layer being of a material different than the shielding layer, the dielectric layer selected from the group comprising BPSG and SiO.sub.2.

### Claim 12

A method of forming a floating gate transistor, comprising:
forming a floating gate construction having opposing lateral sidewalls;
providing opposing source and drain regions operably adjacent the floating gate construction;
forming an oxide layer over the gate sidewalls;
forming sidewall spacers over the oxide layer and outwardly of the gate sidewalls;
forming a shielding layer over the sidewall spacers, the shielding layer comprising Si.sub.3 N.sub.4 having a thickness of about 50 Angstroms to about 200 Angstroms; and
forming a dielectric layer over the shielding layer, the dielectric layer being of a different material than the shielding layer, the dielectric layer selected from the group comprising BPSG and SiO.sub.2.

### Claim 13

A method of forming a floating gate transistor, comprising:
forming a floating gate construction having opposing lateral sidewalls;
providing opposing source and drain regions operably adjacent the floating gate construction;
forming an oxide layer over the gate sidewalls;
forming a shielding layer over the oxide layer, the shielding layer comprising aluminum having a thickness of about 50 Angstroms to about 200 Angstroms;
forming sidewall spacers over the shielding layer and outwardly of the sidewalls; and
forming a dielectric layer over the sidewall spacers, the dielectric layer being of a material different than the shielding layer, the dielectric layer selected from the group comprising BPSG and SiO.sub.2.

### Claim 14

A method of forming a floating gate transistor, comprising:
forming a floating gate construction having opposing lateral sidewalls;
providing opposing source and drain regions operably adjacent the floating gate construction;
forming an oxide layer over the gate sidewalls;
forming sidewall spacers over the oxide layer and outwardly of the gate sidewalls;
forming a shielding layer over the sidewall spacers, the shielding layer comprising aluminum having a thickness of about 50 Angstroms to about 200 Angstroms; and
forming a dielectric layer over the shielding layer, the dielectric layer being of a different material than the shielding layer, the dielectric layer selected from the group comprising BPSG and SiO.sub.2.