Method of forming one-transistor memory cell and structure formed thereby

• US 7,238,566 B2
• Filed: 10/08/2003
• Issued: 07/03/2007
• Est. Priority Date: 10/08/2003
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Chiang, Min-Hsiung
• Primary Examiner(s): Fourson; George R.
• Assistant Examiner(s): GARCIA, JOANNIE A
• Application Number:
  US10/681,643
• Publication Number:
  US 20050077557A1
• Time in Patent Office: 1,364 Days
• Field of Search: 438/210, 438/239, 438/240, 438/243, 438/244, 438/386, 438/387, 438/FOR.220, 438/FOR.430, 438/253, 438/396
• US Class Current: 438/239
• CPC Class Codes: H01L 28/90 having vertical extensions
• CPC Class Codes: H10B 12/0385 Making a connection between the transistor and the capacitor, e.g. buried strap
• CPC Class Codes: H10B 12/05 Making the transistor
• CPC Class Codes: H10B 12/377 having a storage electrode extension located over the transistor

Abstract

A method of forming a one-transistor memory cell includes the steps of: forming a dielectric layer over a substrate having a pass-gate formed thereon; forming an opening in the dielectric layer to expose a portion of the substrate at least adjacent to the pass-gate; forming a capacitor dielectric layer on sidewalls of the opening in the dielectric layer and on the exposed portion of the substrate; and forming an electrode layer over the capacitor dielectric layer. A one-transistor memory cell is also disclosed. The one-transistor memory cell has a substrate having a pass-gate formed thereover. A dielectric layer is formed over the pass-gate and the substrate and has an opening exposing a portion of the substrate adjacent to the pass-gate. A capacitor dielectric layer is formed on sidewalls of the opening and on the exposed portion of the substrate. An electrode layer is formed on the capacitor dielectric layer.

Claims

1. A method of forming a one-transistor memory cell, comprising:

(a) forming a dielectric layer over a substrate having a pass-gate formed thereon;

(b) forming an opening in the dielectric layer to expose a portion of the substrate at least adjacent to the pass-gate;

(c) forming a capacitor dielectric layer on sidewalls of the opening in the dielectric layer and directly on the exposed portion of the substrate; and

(d) forming an electrode layer over the capacitor dielectric layer.

2. The method of claim 1, wherein step (b) further comprises the steps of forming a recess in an isolation region within the substrate, and steps (c) and (d) further comprise forming the capacitor dielectric layer and the electrode layer within the recess of the isolation region.

3. The method of claim 1, wherein steps (c) and (d) comprise:

after step (b), substantially conformally forming the capacitor dielectric layer over the dielectric layer;

forming a planarization layer over the electrode layer; and

removing portions of the planarization layer, the capacitor dielectric layer and the electrode layer directly over the dielectric layer.

4. The method of claim 3, wherein the planarization layer is a dielectric layer.

5. The method of claim 3, wherein the planarization layer is a photoresist layer.

6. The method of claim 5, wherein a portion of said photoresist layer remains in the opening of said dielectric layer after said removing step, the method further comprising the step of removing the portion of said photoresist layer within the opening of the dielectric layer.

7. The method of claim 1, wherein step (b) further comprises using a second dielectric layer formed on a sidewall of the pass-gate as an etching stop layer.

8. The method of claim 1, wherein a space between the pass-gate and the exposed portion of the substrate is from about 400 Å

to about 1500 Å

.

9. The method of claim 1, wherein the capacitor dielectric layer comprises a high dielectric constant material layer.

10. The method of claim 9, wherein the electrode layer comprises a metal layer.

11. The method of claim 1 further comprising:

(e) forming a source/drain (S/D) region within the substrate and adjacent to the pass-gate; and

(f) forming a doped region within the substrate and adjacent to the pass-gate and the electrode layer.

12. The method of claim 11, wherein the doped region has a dopant concentration lower than that of the S/D region.

13. A method of forming a one-transistor memory cell, comprising:

forming a dielectric layer over a substrate having a pass-gate formed thereon;

forming an opening in the dielectric layer to expose a portion of the substrate at least adjacent to the pass-gate;

forming a capacitor dielectric layer comprising a high dielectric constant material layer by atomic layer deposition (ALD) on sidewalls of the opening in the dielectric layer and directly on the exposed portion of the substrate; and

forming an electrode layer over the capacitor dielectric layer.

14. A method of forming a one-transistor memory cell, comprising:

(a) forming an isolation region within a substrate, a pass-gate over the substrate and a first dielectric layer over the substrate including over the isolation region and the pass-gate;

(b) forming an opening through the first dielectric layer to expose a portion of the substrate at least adjacent to the pass-gate, wherein a second dielectric layer on a sidewall of the pass-gate is used as an etch stop layer, and a recess within the isolation region;

(c) forming a capacitor dielectric layer on sidewalls of the opening in the first dielectric layer, at least partially within the recess of the isolation region and on the exposed portion of the substrate;

(d) forming an electrode layer over the capacitor dielectric layer;

(e) forming a source/drain (S/D) region within the substrate and adjacent to the pass-gate; and

(f) forming a doped region within the substrate and adjacent to the pass-gate and the electrode layer.

15. The method of claim 14, wherein the steps (c) and (d) comprise:

after step (b), substantially conformally forming the capacitor dielectric layer over the first dielectric layer;

forming a planarization layer over the electrode layer; and

removing portions of the planarization layer, the capacitor dielectric layer and the electrode layer directly over the first dielectric layer.

16. The method of claim 15, wherein the planarization layer is a dielectric layer.

17. The method of claim 15, wherein the planarization layer is a photoresist layer.

18. The method of claim 17 further comprising the step of removing the photoresist layer within the opening of the first dielectric layer after the removing portions step.

19. The method of claim 14, wherein a space between the pass-gate and the exposed portion of the substrate is from about 400 Å

to about 1500 Å

.

20. The method of claim 14, wherein the capacitor dielectric layer comprises a high dielectric constant material layer.

21. The method of claim 20, wherein the capacitor dielectric layer is formed by atomic layer deposition (ALD).

22. The method of claim 20, wherein the electrode layer comprises a metal layer.

23. The method of claim 14, wherein the doped region has a dopant concentration lower than that of the S/D region.

24. A method of forming a one-transistor memory cell, comprising:

(a) forming a dielectric layer over a substrate having a pass gate formed thereon;

(b) forming an opening in the dielectric layer to expose at least a portion of the substrate adjacent to the pass-gate;

(c) conformally forming a capacitor dielectric layer on sidewalls of the opening in the dielectric layer and directly on the exposed portion of the substrate; and

(d) conformally forming an electrode layer over the capacitor dielectric layer along sidewalls of the opening in the dielectric layer and over the exposed portion of the substrate, leaving a remaining portion of said opening.

25. The method of claim 24, wherein step (b) further comprises the steps of forming a recess in an isolation region within the substrate, and steps (c) and (d) further comprise forming the capacitor dielectric layer and the electrode layer along walls of the recess of the isolation region.

26. The method of claim 24,

wherein portions of the capacitor dielectric layer and electrode layer are formed over a top surface of said dielectric layer, the method further comprising:

forming a planarization layer over the electrode layer and in the remaining portion of said opening; and

removing portions of the planarization layer, the capacitor dielectric layer and the electrode layer over the top surface of said dielectric layer.

27. The method of claim 26, wherein the planarization layer is a dielectric layer.

28. The method of claim 26, wherein the planarization layer is a photoresist layer.

29. The method of claim 28, further comprising the step of removing the photoresist layer within the opening of the dielectric layer after the removing portions step.

30. The method of claim 26, wherein said removing step comprises a CMP process.

31. The method of claim 24, wherein step (b) further comprises using a second dielectric layer formed on a sidewall of the pass-gate as an etching stop layer.

32. The method of claim 24, wherein a space between the pass-gate and the exposed portion of the substrate is from about 400 Å

to about 1500 Å

.

33. The method of claim 24, wherein the capacitor dielectric layer comprises a high dielectric constant material layer.

34. The method of claim 33, wherein the capacitor dielectric layer is formed by atomic layer deposition (ALD).

36. The method of claim 24 further comprising:

(e) forming a source/drain (S/D) region within the substrate and adjacent to the pass-gate; and

(f) forming a doped region within the substrate and adjacent to the pass-gate and the electrode layer.

37. The method of claim 36, wherein the doped region has a dopant concentration lower than that of the S/D region.

35. A method of forming a one-transistor memory cell, comprising;

forming a dielectric layer over a substrate having a pass gate formed thereon;

forming an opening in the dielectric layer to expose at least a portion of the substrate adjacent to the pass-gate;

conformally forming a capacitor dielectric layer comprising a high dielectric constant dielectric layer by atomic layer deposition (ALD) on sidewalls of the opening in the dielectric layer and directly on the exposed portion of the substrate; and

conformally forming an electrode layer comprising a metal layer over the capacitor dielectric layer along sidewalls of the opening in the dielectric layer and over the exposed portion of the substrate, leaving a remaining portion of said opening.