IP Library Granted Patent US 9,190,531
Granted Patent B2
US 9,190,531 · App. 13/725,654 · Granted Nov 17, 2015

Flash memory cell with flair gate

Inventors: Meng Ding (San Jose, CA); YouSeok Suh (Cupertino, CA); Shenqing Fang (Fremont, CA); Kuo-Tung Chang (Saratoga, CA)
Assignee: CYPRESS SEMICONDUCTOR CORPORATION
H01L29/788H01L21/28273H01L21/28282H01L21/762H01L21/76224H01L27/115H01L27/11521H01L27/11568H01L29/4234H01L29/42324H01L29/792H01L27/0207
View Patent ↗
Loading inventors, assignments & file history…
Monitor This Case
Get email alerts when status or documents change.
Order Certified Copies
Most orders are placed with the USPTO same day — all within 24 business hours.
Order via The Patent Place →
Pre-filled with this patent's details
Quick Facts
Patent No.
US 9,190,531
App. No.
13/725,654
Granted
Nov 17, 2015
Kind
B2
Abstract

An embodiment of the present invention is directed to a method of forming a memory cell. The method includes etching a trench in a substrate and filling the trench with an oxide to form a shallow trench isolation (STI) region. A portion of an active region of the substrate that comes in contact with the STI region forms a bitline-STI edge. The method further includes forming a gate structure over the active region of the substrate and over the STI region. The gate structure has a first width substantially over the center of the active region of the substrate and a second width substantially over the bitline-STI edge, and the second width is greater than the first width.

Claims (26)

1. A method of forming a memory cell, the method comprising:

etching a trench in a substrate;

filling the trench with an oxide to form a shallow trench isolation (STI) region, wherein a portion of an active region of the substrate that comes in contact with the STI region forms a bitline-STI edge;

forming a gate structure over the active region of the substrate and over the STI region wherein the gate structure comprises a charge trapping layer; and

forming a wordline structure having first and second widths and having portions of the wordline structure of the first width centered above a bit line and portions of the wordline structure of the second width centered above the STI region and formed to extend across the STI region over the bitline-STI edge, wherein the second width is greater than the first width and wherein a lower surface of the portions of the wordline structure of the first width and the lower surface of the portions of the wordline structure of the second width lie in the same plane wherein the top surfaces of the portions of the wordline structure of the second width lie in the same plane and are centered along a same line as is the portions of the wordline structure of the first width.

2. The method as recited in claim 1 wherein said forming of the gate structure comprises:

forming a preliminary gate structure over the substrate;

applying a mask over the memory cell, wherein the mask has the first width substantially over the center of the active region of the substrate and the second width substantially over the bitline-STI edge; and

etching the preliminary gate structure to form the gate structure.

3. The method as recited in claim 1 further comprising:

polishing the memory cell with a CMP process.

4. The method as recited in claim 2 further comprising:

forming a polysilicon layer over the gate structure and the STI region.

5. The method as recited in claim 1 wherein the charge trapping layer comprises an oxide-nitride-oxide layer or an oxide-Silicon Rich Nitride-oxide layer.

6. The method as recited in claim 1 wherein the gate structure comprises a floating gate.

7. A memory cell comprising:

a substrate;

a shallow trench isolation (STI) region etched at a location in the substrate, wherein a portion of an active region of the substrate that comes in contact with the STI region forms a bitline-STI edge; and

a gate structure formed over the active region of the substrate and over the STI region wherein the gate structure comprises a charge trapping layer for storing memory cell information, the gate structure having a first width substantially over the center of the active region of the substrate and a second width substantially over the bitline-STI edge, wherein the second width is greater than the first width and wherein a lower surface of the portions of the gate structure of the first width and a lower surface of the portions of the gate structure of the second width lie in the same plane wherein the top surfaces of the portions of the wordline structure of the second width lie in the same plane and are centered along a same line as is the portions of the wordline structure of the first width.

8. The memory cell as recited in claim 7 further comprising:

a polysilicon layer formed over the gate structure.

9. The memory cell as recited in claim 7 wherein the STI region comprises an oxide.

10. The memory cell as recited in claim 7 wherein the gate structure comprises a charge trapping layer.

11. The memory cell as recited in claim 10 wherein the charge trapping layer comprises an oxide-nitride-oxide layer or an oxide-silicon rich nitride-oxide layer.

12. The memory cell as recited in claim 7 wherein the gate structure comprises a floating gate.

13. The memory cell as recited in claim 7 wherein the memory cell is a NAND memory cell.

Assignments (4)
CORRECTIVE ASSIGNMENT TO CORRECT THE 8647899 PREVIOUSLY RECORDED ON REEL 035240 FRAME 0429. ASSIGNOR(S) HEREBY CONFIRMS THE SECURITY INTERST. Recorded Nov 3, 2020
From: CYPRESS SEMICONDUCTOR CORPORATION; SPANSION LLC
To: MORGAN STANLEY SENIOR FUNDING, INC.
Reel/Frame 058002/0470 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Dec 14, 2016
From: CYPRESS SEMICONDUCTOR CORPORATION
To: MONTEREY RESEARCH, LLC
Reel/Frame 040911/0238 →
PARTIAL RELEASE OF SECURITY INTEREST IN PATENTS Recorded Aug 11, 2016
From: MORGAN STANLEY SENIOR FUNDING, INC., AS COLLATERAL AGENT
To: CYPRESS SEMICONDUCTOR CORPORATION; SPANSION LLC
Reel/Frame 039708/0001 →
SECURITY INTEREST Recorded Mar 21, 2015
From: CYPRESS SEMICONDUCTOR CORPORATION; SPANSION LLC
To: MORGAN STANLEY SENIOR FUNDING, INC.
Reel/Frame 035240/0429 →
Continuity (2)
Division 11801823 · May 10, 2007
Related Publication 20130105878A1 · May 2, 2013