Method of making a non-volatile memory (NVM) with trap-up reduction
View Patent ↗A method for forming a semiconductor device includes forming a select gate over a substrate and forming a charge storage layer and a control gate over the select gate. The charge storage layer and control gate overlap a first sidewall of the select gate and the charge storage layer is between the select gate and the control gate. A protective spacer is formed, wherein the protective spacer has a first portion adjacent a first sidewall of the charge storage layer and on the substrate, and the protective spacer is thinned. After thinning the protective spacer, a sidewall spacer is formed over the protective spacer, wherein the sidewall spacer has a first portion on the substrate, and the first portion of the protective spacer is between the first sidewall of the control gate and the first portion of the sidewall spacer.
1. A method for forming a semiconductor device, comprising:
forming a select gate over a substrate;
forming a charge storage layer and a control gate over the select gate, wherein the charge storage layer and control gate overlap a first sidewall of the select gate and the charge storage layer is between the select gate and the control gate;
forming a protective spacer, wherein the protective spacer has a first portion adjacent a first sidewall of the charge storage layer and on the substrate;
thinning the protective spacer;
forming logic gates for logic devices, wherein the thinning of the protective spacer occurs during the forming the logic gates; and
after the thinning the protective spacer, forming a sidewall spacer over the protective spacer, wherein the sidewall spacer has a first portion on the substrate, and the first portion of the protective spacer is between the first sidewall of the control gate and the first portion of the sidewall spacer.
2. The method of claim 1 , wherein the forming the protective spacer is formed such that a second portion of the protective spacer is adjacent a second sidewall of the control gate, wherein the second sidewall of the control gate is over the select gate.
3. The method of claim 2 , wherein the forming the sidewall spacer is formed such that a second portion of the sidewall spacer is formed adjacent the second portion of the protective spacer.
4. The method of claim 3 , wherein the forming the protective spacer is formed such that a third portion of the protective spacer is adjacent a second sidewall of the select gate, wherein the first sidewall of the select gate is between the second sidewall of the select gate and the first sidewall of the control gate.
5. The method of claim 4 , wherein the forming the sidewall spacer is formed such that a third portion of the sidewall spacer is formed adjacent the third portion of the protective spacer.
6. The method of claim 2 , wherein the forming the protective spacer is formed such that a second portion of the protective spacer is adjacent a second sidewall of the control gate, wherein the second sidewall of the control gate is over the select gate, and a third portion of the protective spacer is adjacent a second sidewall of the select gate, wherein the first sidewall of the select gate is between the second sidewall of the select gate and the first sidewall of the control gate.
7. The method of claim 1 , further comprising forming source/drain regions in the substrate adjacent the select gate and the control gate, such that the select gate and control gate are between the source/drain regions.
8. The method of claim 1 , wherein the protective spacer comprises an oxide and the sidewall spacer comprises at least one of an oxide or a nitride.
9. The method of claim 1 ,
wherein the protective spacer is formed prior to the forming the logic gates.
10. The method of claim 1 , wherein during the forming the logic gates, the thinning of the protective spacer occurs as a result of ashing or cleaning.
11. The method of claim 1 , wherein the charge storage layer comprises nanocrystals surrounded by a dielectric.
12. A method for forming a semiconductor device, comprising:
forming a select gate over a substrate;
forming a charge storage layer and a control gate over the select gate, wherein the charge storage layer and control gate overlap a first sidewall of the select gate and the charge storage layer is between the select gate and the control gate;
forming a protective spacer adjacent the charge storage layer, the control gate, and a second sidewall of the select gate, wherein the protective spacer adjacent a first sidewall of the charge storage layer is on the substrate;
forming logic gates for logic devices;
during the forming the logic gates, thinning the protective spacer; and
forming a sidewall spacer over the protective spacer, wherein the protective spacer is between the sidewall spacer and the control gate and between the sidewall spacer and the first sidewall of the select gate.
13. The method of claim 12 , wherein the forming the sidewall spacer over the protective spacer comprises forming the sidewall spacer adjacent to sidewalls of the logic gates.
14. The method of claim 13 , wherein the sidewall spacer is immediately adjacent to the sidewalls of the logic gate.
15. The method of claim 12 , wherein during the forming the logic gates, the thinning of the protective spacer occurs as a result of ashing or cleaning.
16. The method of claim 12 , further comprising forming source/drain regions in the substrate adjacent the select gate and the control gate, such that the select gate and control gate are between the source/drain regions.
17. The method of claim 16 , wherein forming source/drain regions further comprises forming source/drain regions adjacent the logic gates.
18. The method of claim 12 , wherein the protective spacer comprises an oxide.
19. The method of claim 18 , wherein the sidewall spacer comprises at least one of an oxide or a nitride.
20. The method of claim 12 , wherein the charge storage layer comprises nanocrystals surrounded by a dielectric.