Methods of sputtering a protective coating on a semiconductor substrate

• US 7,601,246 B2
• Filed: 09/29/2004
• Issued: 10/13/2009
• Est. Priority Date: 09/29/2004
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Yen, Biming, Loewenhardt, Peter, Kim, Jisoo, Shon, Jong
• Primary Examiner(s): Nguyen; Nam X
• Assistant Examiner(s): BERMAN, JASON
• Application Number:
  US10/952,088
• Publication Number:
  US 20090020417A1
• Time in Patent Office: 1,840 Days
• Field of Search: 204/192.23, 204/192.25
• US Class Current: 204/192.23
• CPC Class Codes: C23C 14/185 by cathodic sputtering
• CPC Class Codes: C23C 14/3457 using other particles than noble gas ions C23C14/0036, C23C14/46 take precedence
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/76814 post-treatment or after-treatment, e.g. cleaning or removal of oxides on underlying conductors
• CPC Class Codes: H01L 2221/1063 Sacrificial or temporary thin dielectric films in openings in a dielectric

Abstract

Methods of depositing a protective coating of a silicon-containing or metallic material onto a semiconductor substrate include sputtering such material from an electrode onto a semiconductor substrate in a plasma processing chamber. The protective material can be deposited onto a multi-layer mask overlying a low-k material and/or onto the low-k material. The methods can be used in dual damascene processes to protect the mask and enhance etch selectivity, to protect the low-k material from carbon depletion during resist strip processes, and/or protect the low-k material from absorption of moisture.

Claims

1. A method of depositing a protective coating of a silicon-containing material on a semiconductor substrate in a dual damascene process, the method comprising:

providing a semiconductor substrate in a capacitively-coupled plasma processing chamber including a first electrode of a silicon-containing material and a second electrode, the semiconductor substrate comprising a low-k dielectric layer and a multi-layer mask including a patterned top imaging layer over the low-k dielectric layer, the semiconductor substrate being supported on the second electrode and the first electrode comprising a showerhead electrode;

supplying a first process gas through the first electrode into a gap between the first and second electrodes of the plasma processing chamber; and

energizing the first process gas into the plasma state and sputtering the silicon-containing material from the first electrode and forming a protective coating of the sputtered material on the imaging layer, without substantially etching the semiconductor substrate.

2. The method of claim 1, wherein the silicon-containing material is doped silicon, un-doped silicon or silicon carbide.

3. The method of claim 1, wherein the first process gas is energized into the plasma state by either:

(i) grounding the first electrode and applying up to about 1000 W power to the second electrode at two different frequencies including a first frequency of less than about 10 MHz and a second frequency of more than about 12 MHz;

or

(ii) applying at least about 100 W power to the first electrode at a first frequency and applying power to the second electrode at a second frequency.

4. The method of claim 3, wherein:

the first electrode is an upper electrode having a bottom surface facing an upper surface of the semiconductor substrate when the semiconductor substrate is supported in the plasma processing chamber, and the second electrode is an electrostatic chuck on which the semiconductor substrate is supported;

for (i), a ratio of the area of a first electrical ground surface of the plasma processing chamber to the area of the upper surface of the semiconductor substrate is less than about 5; and

for (ii), a ratio of the area of a second electrical ground surface of the plasma processing chamber to the area of the bottom surface of the first electrode is less than about 5.

5. The method of claim 1, wherein:

the first process gas comprises H₂ and inert gas;

the H₂ is supplied into the plasma processing chamber at a lower flow rate than the inert gas; and

the plasma processing chamber is at a pressure of about 10 mTorr to about 300 mTorr.

6. The method of claim 1, wherein the imaging layer is composed of a photoresist material having a 193 nm exposure wavelength, and the mask comprises a bottom layer composed of a material having a 248 nm or 365 nm exposure wavelength on the low-k dielectric layer, and an intermediate layer of an antireflective coating material between the bottom layer and the imaging layer.

7. The method of claim 1, further comprising, after forming the protective coating on the imaging layer:

supplying a second process gas into the plasma processing chamber; and

energizing the second process gas into the plasma state and etching openings through the mask,

wherein the protective coating increases the etching selectivity of the imaging layer with respect to at least one layer of the mask which underlies the imaging layer.

8. The method of claim 1, further comprising, prior to providing or after providing, the semiconductor substrate in the plasma processing chamber:

supplying a cleaning gas into the plasma processing chamber; and

energizing the cleaning gas into the plasma state and sputtering contaminants from the first electrode.

9. A method of depositing a protective coating of a silicon-containing material on a semiconductor substrate in a dual damascene process, the method comprising:

providing a semiconductor substrate in a capacitively-coupled plasma processing chamber including a first electrode of a silicon-containing material and a second electrode, the semiconductor substrate comprising a patterned low-k dielectric layer and a patterned multi-layer mask over the low-k dielectric layer, the semiconductor substrate being supported on the second electrode and the first electrode comprising a showerhead electrode;

supplying a first process gas through the first electrode into a gap between the first and second electrodes of the plasma processing chamber; and

energizing the first process gas into the plasma state and sputtering the silicon-containing material from the first electrode and forming a protective coating of the sputtered material on sidewalls of features in the low-k dielectric layer, without substantially etching the semiconductor substrate.

10. The method of claim 9, wherein the silicon-containing material is un-doped silicon, doped silicon or silicon carbide.

11. The method of claim 9, wherein the first process gas is energized into the plasma state by either:

(i) grounding the first electrode and applying up to about 1000 W power to the second electrode at two different frequencies including a first frequency of less than about 10 MHz and a second frequency of more than about 12 MHz;

or

(ii) applying at least about 100 W power to the first electrode at a first frequency and applying power to the second electrode at a second frequency.

12. The method of claim 11, wherein:

the first electrode is an upper electrode having a bottom surface facing an upper surface of the semiconductor substrate when the semiconductor substrate is supported in the plasma processing chamber, and the second electrode is an electrostatic chuck on which the semiconductor substrate is supported;

for (i), a ratio of the area of a first electrical ground surface of the plasma processing chamber to the area of the upper surface of the semiconductor substrate is less than about 5; and

for (ii), a ratio of the area of a second electrical ground of the plasma processing chamber to the area of the bottom surface of the first electrode is less than about 5.

13. The method of claim 9, wherein:

the first process gas comprises H₂ and inert gas;

H₂ is supplied into the plasma processing chamber at a lower flow rate than the inert gas; and

the plasma processing chamber is at a pressure of about 10 mTorr to about 300 mTorr.

14. The method of claim 9, further comprising, after forming the protective coating on the low-k material:

supplying a second process gas into the plasma processing chamber or into a different plasma processing chamber; and

energizing the second process gas into the plasma state and stripping the multi-layer mask from the semiconductor substrate,

wherein the low-k dielectric material contains carbon and the protective coating reduces carbon depletion of the low-k dielectric layer during the stripping of the multi-layer mask from the semiconductor substrate.

15. The method of claim 14, wherein the second process gas contains oxygen and the silicon-containing material is deposited on the semiconductor substrate and converted to silicon oxide during stripping of the mask.

16. The method of claim 9, further comprising, prior to providing or after providing, the semiconductor substrate in the plasma processing chamber;

supplying a cleaning gas into the plasma processing chamber; and

energizing the cleaning gas into the plasma state and sputtering contaminants from the first electrode.

17. A method of depositing a protective coating of a silicon-containing material on a semiconductor substrate in a dual damascene process, the method comprising:

providing a semiconductor substrate in a capacitively-coupled plasma processing chamber including a first electrode of a silicon-containing material and a second electrode, the semiconductor substrate comprising a patterned low-k dielectric layer, the semiconductor substrate being supported on the second electrode and the first electrode comprising a showerhead electrode;

supplying a process gas through the first electrode into a gap between the first and second electrodes of the plasma processing chamber; and

energizing the process gas into the plasma state and sputtering the silicon-containing material from the first electrode and forming a protective coating of the sputtered material on the low-k dielectric layer, without substantially etching the semiconductor substrate.

18. The method of claim 17, wherein the silicon-containing material is un-doped silicon, doped silicon or silicon carbide.

19. The method of claim 17, wherein the process gas is energized into the plasma state by either:

(i) grounding the first electrode and applying up to about 1000 W power to the second electrode at two different frequencies including a first frequency of less than about 10 MHz and a second frequency of more than about 12 MHz;

or

(ii) applying at least about 100 W power to the first electrode at a first frequency and applying power to the second electrode at a second frequency.

20. The method of claim 19, wherein:

the first electrode is an upper electrode having a bottom surface facing an upper surface of the semiconductor substrate when the semiconductor substrate is supported in the plasma processing chamber, and the second electrode is an electrostatic chuck on which the semiconductor substrate is supported;

for (i), a ratio of the area of a first electrical ground surface of the plasma processing chamber to the area of the upper surface of the semiconductor substrate is less than about 5; and

for (ii), a ratio of the area of a second electrical ground surface of the plasma processing chamber to the area of the bottom surface of the first electrode is less than about 5.

21. The method of claim 17, wherein:

the process gas comprises H₂ and inert gas;

the H₂ is supplied into the plasma processing chamber at a lower flow rate than the inert gas; and

the plasma processing chamber is at a pressure of about 10 mTorr to about 300 mTorr.

22. The method of claim 17, further comprising, prior to providing or after providing, the semiconductor substrate in the plasma processing chamber:

supplying a cleaning gas into the plasma processing chamber; and

energizing the cleaning gas into the plasma state and sputtering contaminants from, and thereby cleaning, the first electrode.

23. A method of depositing a protective coating of a silicon-containing material on a semiconductor substrate in a dual damascene process, the method comprising:

providing a semiconductor substrate in a capacitively-coupled plasma processing chamber including a first electrode of a silicon-containing material and a second electrode, the semiconductor substrate comprising a low-k dielectric layer and an optional multi-layer mask including a patterned top imaging layer over the low-k dielectric layer, the semiconductor substrate being supported on the second electrode and the first electrode comprising a showerhead electrode;

supplying a process gas through the first electrode into a gap between the first and second electrodes of the plasma processing chamber; and

energizing the process gas into the plasma state and sputtering the silicon-containing material from the first electrode and forming a protective coating of the sputtered material (i) on sidewalls of features in the low-k dielectric layer or (ii) on the optional imaging layer, without substantially etching the semiconductor substrate.

24. The method of claim 23, wherein the protective coating is formed on the imaging layer.

25. The method of claim 23, wherein the protective coating is formed on the sidewalls of the features of the low-k material.

26. The method of claim 23, wherein the semiconductor substrate does not include the multi-layer mask and the protective coating is formed on the low-k material.

27. The method of claim 23, wherein the process gas is energized into the plasma state by:

(i) grounding the first electrode and applying up to about 1000 W power to the second electrode at two different frequencies including a first frequency of less than about 10 MHz and a second frequency of more than about 12 MHz;

or

(ii) applying at least about 100 W power to the first electrode at a first frequency and applying power to the second electrode at a second frequency which is different from the first frequency.

28. The method of claim 27, wherein:

the first electrode is an upper electrode having a bottom surface facing an upper surface of the semiconductor substrate when the semiconductor substrate is supported in the plasma processing chamber, and the second electrode is an electrostatic chuck on which the semiconductor substrate is supported;

for (i), a ratio of the area of a first electrical ground of the plasma processing chamber to the area of the upper surface of the semiconductor substrate is less than about 5; and

for (ii), a ratio of the area of a second electrical ground of the plasma processing chamber to the area of the bottom surface of the first electrode is less than about 5.

29. The method of claim 23, further comprising, prior to providing or after providing, the semiconductor substrate in the plasma processing chamber:

supplying a cleaning gas into the plasma processing chamber; and

energizing the cleaning gas into the plasma state and sputtering contaminants from the first electrode.