Plasma etching method using polymer deposition and method of forming contact hole using the plasma etching method

• US 6,617,253 B1
• Filed: 07/20/2000
• Issued: 09/09/2003
• Est. Priority Date: 07/20/1999
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Chu, Chang-Woong, Jeong, Sang-Sup, Kim, Ji-Soo, Ahn, Tae-Hyuk
• Primary Examiner(s): Kunemund, Robert
• Assistant Examiner(s): UMEZ ERONINI, LYNETTE T
• Application Number:
  US09/620,022
• Time in Patent Office: 1,146 Days
• Field of Search: 438/702, 438/706, 438/712
• US Class Current: 438/702
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics

Abstract

A plasma etching method using selective polymer deposition, and a method of forming a contact hole using the plasma etching method are provided. The plasma etching method uses a method of reinforcing an etch mask by selectively depositing polymer on only a photoresist pattern, which is an etch mask. That is, a dielectric film is plasma etched for a predetermined period of time using the photoresist pattern as an etch mask, and polymer is selectively deposited on only the photoresist pattern which is thinned by plasma etching, thereby forming a polymer layer. Following this, the dielectric film is plasma etched using the photoresist pattern and the polymer layer as a mask. Thus, dielectric film etching providing high resolution and an excellent profile can be performed using the thinned photoresist pattern as a mask, and a contact hole and a self-aligned contact hole each having a very high aspect ratio, and a self-aligned contact hole having an excellent profile, can be formed.

Claims

1. A plasma etching method, in which a dielectric film on a wafer is etched by plasma using a photoresist pattern as a mask, the method comprising:

(a) plasma etching an upper portion of the dielectric film using the photoresist pattern as a mask by establishing an average power of a power supply within a given range, to form an opening the dielectric film;

(b) selectively depositing a polymer layer on the photoresist pattern, the polymer layer having a thick portion on the surface of the photoresist pattern and a substantially thinner portion on the surface of the opening in the dielectric film; and

(c) plasma etching the remaining portion of the dielectric film using the photoresist pattern and the polymer layer as a mask by establishing the average power of the power supply within the given range.

2. The method of claim 1, wherein the dielectric film is etched to a depth by repeating steps (b) and (c) one or more times.

3. The method of claim 1, wherein the polymer depositing of step (b) is achieved by setting the average power of a bias power supply that is applied to the wafer to accelerate the plasma within a range that is lower than that of the plasma etching steps (a) and (c).

4. The method of claim 1, wherein a gas used for the etching of the dielectric film and the depositing of the polymer is C_xF_y-series or C_aH_bF_c-series gas.

5. The method of claim 4, wherein the gas further includes an inert gas to allow plasma to be stably produced and polymer to be stably and uniformly deposited on the substrate.

6. The method of claim 4, which further comprises supplying a gas, in step (c), for etching polymer deposited by step (b) on the sidewall of the opening in a dielectric film formed by step (a).

7. The method of claim 6, wherein the gas for etching the polymer is O₂, N₂, CO or CO₂.

8. The method of claim 1, wherein a conductive layer is formed in the lower portion of the dielectric film, and wherein a contact hole that exposes the conductive layer is formed by etching the dielectric film using the plasma etching steps (a) and (c).

9. The method of claim 8, wherein, during the depositing of the polymer in step (b), the average power of a source power supply that is applied to generate the plasma is set to a range that is higher than that of the plasma etching steps (a) and (c).

10. The method of claim 1, wherein a conductive layer pattern and a capping layer that covers the conductive layer pattern are formed in a lower portion of the dielectric film, and wherein a self-aligned contact hole that exposes the capping layer is formed by etching the dielectric film using the plasma etching steps (a) and (c).

11. The method of claim 10, wherein during the depositing of the polymer in step (b), the average power of a source power supply that is applied to generate the plasma is established within a range that is lower than that of the plasma etching steps (a) and (c).

12. The method of claim 1, wherein a first conductive layer is formed in a lower portion of the dielectric film, a second conductive layer is formed at a depth in the dielectric film, and first and second contact holes having different depths that expose the first and second conductive layers, respectively, are formed simultaneously by etching the dielectric film using the plasma etching steps (a) and (c).

13. The method of claim 12, wherein during the depositing of the polymer in step (b), the average power of a source power supply that is applied to generate the plasma, is set to a range that is lower than that of the plasma etching steps (a) and (c).

14. A contact hole forming method comprising:

(a) forming a dielectric film on a conductive layer on a substrate and forming a photoresist pattern on the dielectric film;

(b) plasma etching the dielectric film to form an opening therein, using the photoresist pattern as a mask by setting the average power of a bias power supply that is applied to the substrate to accelerate plasma to a high level within a defined range wherein plasma etching is more predominant than deposition of polymer;

(c) selectively forming a polymer layer on the photoresist pattern by setting the average power of the bias power supply to a low level within a defined range where polymer deposition is more predominant than plasma etching such that the polymer layer has a thick portion on the surface of the photoresist pattern and a substantially thinner portion on the surface of the opening in the dielectric film; and

(d) plasma etching the dielectric film using the photoresist pattern and the polymer layer as a mask by setting the average power of the bias power supply to the high level.

15. The method of claim 14, wherein a contact hole that exposes the conductive layer is formed by repeating steps (c) and (d) one or more times.

16. The method of claim 14, wherein, in step (c), the difference between the thickness of a polymer layer on the photoresist pattern and the thickness of a polymer layer on the bottom surface of a contact hole formed by etching the dielectric film is increased by setting the temperature of the substrate to a level that is lower than that of the plasma etching steps (b) and (d).

17. The method of claim 14, wherein, in step (c), the difference between the thickness of a polymer layer on the photoresist pattern and the thickness of a polymer layer on the bottom surface of a contact hole formed by etching the dielectric film is increased by setting the internal pressure of a reactor to a level that is higher than that of the plasma etching steps (b) and (d).

18. The method of claim 14, wherein, in step (c), the difference between the thickness of a polymer layer on the photoresist pattern and the thickness of a polymer layer on the bottom surface of a contact hole formed by etching the dielectric film is increased by setting the average power of a source power supply that is applied to generate the plasma to a level that is higher than that of the plasma etching steps (b) and (d).

19. The method of claim 14, which further comprises supplying a gas, in step (d), for etching polymer deposited by step (c) on the sidewall of a hole in a dielectric film formed by step (b).

20. The method of claim 19, wherein the gas for etching the polymer is O₂, N₂, CO or CO₂.

21. A self-aligned contact hole forming method comprising:

(a) successively forming a first dielectric film and a conductive layer pattern on a semiconductor substrate;

(b) forming a capping layer to cover the conductive layer pattern;

(c) forming a second dielectric film overlying the conductive layer pattern and the capping layer;

(d) forming a photoresist pattern on the second dielectric film;

(e) performing primary plasma etching on the second dielectric film to form an opening therein using the photoresist pattern as a mask to expose a portion of the capping layer by establishing an average power of a power supply within a given range;

(f) selectively depositing polymer on the photoresist pattern and on the exposed capping layer the polymer layer having a thick portion on the surface of the photoresist pattern and a substantially thinner portion on the surface of the opening in the dielectric film; and

(g) performing secondary plasma etching on the second dielectric film using the photoresist pattern, the capping layer and the polymer layer on the photoresist pattern and on the capping layer as a mask by establishing the average power of the power supply within the given range.

22. The method of claim 21, wherein the primary plasma etching of step (e) comprises:

(e1) plasma etching the second dielectric film using the photoresist pattern as a mask by setting the average power of the bias power supply that is applied to the substrate to accelerate plasma to a high level within a defined range wherein plasma etching is more predominant than polymer deposition;

(e2) selectively forming a polymer layer on the photoresist pattern by setting the average power of the bias power supply to a low level within a defined range wherein polymer deposition is more predominant than plasma etching; and

(e3) plasma etching the second dielectric film using the photoresist pattern and the polymer layer as a mask by setting the average power of the bias power supply to the high level,

wherein the capping layer is exposed by repeating steps (e2) and (e3) one or more times.

23. The method of claim 21, wherein a contact hole that exposes the conductive layer is formed by repeating steps (f) and (g) one or more times.

24. The method of claim 21, wherein, in step (f), the polymer layer is formed by setting the average power of the bias power supply that is applied to the substrate to accelerate plasma to a low level within a defined range wherein polymer deposition is more predominant than plasma etching.

25. The method of claim 21, wherein, in step (f) of forming a polymer layer, the difference between the thickness of the polymer layer stacked on the photoresist pattern and the thickness of the polymer layer on the capping layer exposed by the etching of the second dielectric film is reduced by setting the temperature of the substrate to a level that is higher than that of the plasma etching steps (e) and (g).

26. The method of claim 21, wherein, in step (f) of forming a polymer layer, the difference between the thickness of the polymer layer stacked on the photoresist pattern and the thickness of the polymer layer on the capping portion exposed by the etching of the second dielectric film is reduced by setting the internal pressure of a reactor to a level which is lower than that of the plasma etching steps (e) and (g).

27. The method of claim 21, wherein, in step (f) of forming a polymer layer, the difference between the thickness of the polymer layer stacked on the photoresist pattern and the thickness of the polymer layer on the capping layer exposed by the etching of the second dielectric film is reduced by setting the average power of a source power supply that is applied to generate the plasma to a level that is lower than that of the plasma etching steps (e) and (g).

28. The method of claim 21, which further comprises supplying a gas, in step (g), for etching polymer deposited by step (f) on the sidewall of the hole in the second dielectric film formed by step (e).

29. The method of claim 28, wherein the gas for etching the polymer is O₂, N₂, CO or CO₂.

30. A plasma etching method, in which a dielectric film on a wafer is etched by plasma with a photoresist pattern as a mask using a plasma equipment comprising a source power supply and a bias power supply, the method comprising:

(a) plasma etching a first portion of the dielectric film to form an opening therein, using the photoresist pattern as a mask for a first period of time;

(b) selectively depositing polymer on the photoresist pattern, thereby forming a polymer layer thereon for a second period of times the polymer layer having a thick portion on the surface of the photoresist pattern and a substantially thinner portion on the surface of the opening in the dielectric film; and

(c) plasma etching a second portion of the dielectric film using the photoresist pattern and the polymer layer as a mask for a third period of time.

31. The plasma etching method of claim 30, wherein the first period of time is approximately 1 to 3 minutes, and wherein, during the plasma etching, the source power supply and the bias power supply apply RF power of between 2000 and 3000W and RF power of between 1000 and 1500W, respectively.

32. The plasma etching method of claim 30, wherein the second period of time is approximately 15 to 40 seconds, and wherein the depositing of the polymer is performed with RF power of approximately between 0 and 900W.

33. The plasma etching method of claim 30, wherein the third period of time is approximately 1 to 2 minutes, and wherein, during the plasma etching, the source power supply and the bias power supply apply RF power of approximately between 2000 and 3000W and RF power of approximately between 1000 and 1500W, respectively.

34. A method of forming a contact hole in a dielectric film, the method comprising:

(a) plasma etching an opening in an upper portion of a dielectric film, using a photoresist pattern as a mask;

(b) depositing a polymer layer having a thick portion on the surface of the photoresist patter and a substantially thinner portion on the surface of the opening in the dielectric film; and

(c) thereafter plasma etching the remaining portion of the dielectric film below the opening to form a contact hole in the dielectric film, using the photoresist pattern and the thick portion of the polymer layer deposited on the photoresist pattern as a mask.

35. The method of claim 34, wherein the depositing a polymer layer supplement a thickness of the mask.