System and method for EEPROM architecture

• US 8,470,669 B2
• Filed: 12/02/2010
• Issued: 06/25/2013
• Est. Priority Date: 12/04/2009
• Status: Active Grant

• Current Assignee: Semiconductor Manufacturing International Corporation
• Original Assignee: Semiconductor Manufacturing International Corporation
• Inventors: Yang, Zhen, Huang, Shenghe, Jan, Yipeng
• Primary Examiner(s): MENZ, LAURA MARY
• Application Number:
  US12/959,229
• Publication Number:
  US 20110133264A1
• Time in Patent Office: 936 Days
• Field of Search: 438/264, 438/257, 438/259
• US Class Current: 438/264
• CPC Class Codes: H01L 21/26586 characterised by the angle between the ion beam and the crystal planes or the main crystal surface
• CPC Class Codes: H01L 29/40114 the electrodes comprising a conductor-insulator-conductor-insulator-semiconductor structure
• CPC Class Codes: H01L 29/42324 Gate electrodes for transistors with a floating gate
• CPC Class Codes: H01L 29/66825 with a floating gate H01L29/6684 takes precedence
• CPC Class Codes: H01L 29/7881 Programmable transistors with only two possible levels of programmation H01L29/7888 takes precedence
• CPC Class Codes: H10B 41/30 characterised by the memory core region
• CPC Class Codes: H10B 41/35 with a cell select transistor, e.g. NAND

Abstract

A method for manufacturing an Electrically Erasable Programmable Read-Only Memory (EEPROM) device includes providing a substrate and forming a gate oxide over the substrate. Also, the method includes providing a mask overlying the gate oxide layer, the mask defining a tunnel opening. The method additionally includes performing selective etching over the mask to form a tunnel oxide layer. The method includes forming a floating gate over the tunnel oxide layer and a selective gate over the gate oxide layer. The method includes angle doping a region of the substrate using the floating gate as a mask to obtain a first doped region. The method further includes forming a dielectric layer over the floating gate and a control gate over the dielectric layer. The method additionally includes angle doping a second region of the substrate using the selective gate as a mask to obtain a second doped region, wherein the first and second doped regions partially overlap.

Claims

1. A method of manufacturing an Electrically Erasable Programmable Read-Only Memory (EEPROM), the method comprising:

providing a semiconductor substrate having an active region;

forming a gate oxide layer overlying the semiconductor substrate;

providing a first mask overlaying the gate oxide layer, the first mask defining a tunnel gate opening;

selectively etching the gate oxide layer using the first mask to form a tunnel oxide layer;

depositing a first polysilicon layer overlying the gate oxide layer and the tunnel oxide layer;

etching the first polysilicon layer to obtain a floating gate structure and a selective gate structure, the floating gate structure having a top and a first side and a second side, and the selective gate structure having a third side and a fourth side;

angle doping the floating gate structure with a first dopant at a first dose and a first energy level to obtain a first doped region and a second doped region;

forming a dielectric layer structure overlying the gate oxide layer, the tunnel oxide layer, the selective gate structure, and the top and the first and second sides of the floating gate structure;

removing the dielectric layer except a portion covering the top and the first and second sides of the floating gate structure;

depositing a second polysilicon layer overlying the portion of the dielectric layer structure covering the top and the first and second sides of the floating gate structure to form a control gate structure; and

angle doping the selective gate of the selective gate with a second dopant at a second dose and a second energy level to obtain a third doped region;

wherein the first doped and second doped partially extend underneath the first and the second sides of the floating gates,

wherein the third doped region partially overlaps the second doped region.

2. The method of claim 1, wherein the gate oxide layer comprises a thickness ranging from about 150 Angstroms to about 370 Angstroms.

3. The method of claim 1, wherein the tunnel oxide layer comprises a thickness ranging from about 40 Angstroms to about 160 Angstroms.

4. The method of claim 1, wherein the control gate structure comprises a thickness ranging from about 1000 Angstroms to about 3000 Angstroms.

5. The method of claim 1, wherein the dielectric layer structure comprises a thickness of about 300 Angstroms.

6. The method of claim 1, wherein the dielectric layer structure comprises an oxide-nitride-oxide layer.

7. The method of claim 6, wherein the oxide-nitride-oxide layer comprises a silicon nitride layer interposed between silicon oxide layers, the silicon nitride layer having a thickness of about 100 Angstroms.

8. The method of claim 1, wherein the angle doping comprises an impurity comprising a material selected from the group consisting of phosphorous and arsenic and under an angle ranging between 30°

to 60°

.

9. The method of claim 1, wherein the first energy level is approximately 40 KeV.

10. The method of claim 1, wherein the first concentration level is about 10E13 ions/cm².

11. The method of claim 1, wherein the first dopant comprises arsenic ions.

12. The method of claim 1, wherein the gate oxide layer comprises high-voltage gate oxide material.