Plasma etching system and plasma etching method

• US 5,593,540 A
• Filed: 04/27/1995
• Issued: 01/14/1997
• Est. Priority Date: 10/19/1992
• Status: Expired due to Term

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Hitachi, Ltd., Hitachi Tokyo Electronics Company Limited (Hitachi, Ltd.), Tokyo Electron Limited, Tokyo Electron Yamanashi Ltd. (Tokyo Electron Limited)
• Inventors: Miura, Yutaka, Nozawa, Akira, Hirano, Motohiro, Matsuo, Hiromitsu, Tozawa, Shigeki, Ito, Yoshikazu, Iimuro, Shunichi, Tomita, Kazushi
• Primary Examiner(s): Breneman, R. Bruce
• Assistant Examiner(s): CHANG, JONI YUK YING
• Application Number:
  US08/429,648
• Time in Patent Office: 628 Days
• Field of Search: 156/643.1, 156/646.1, 156/345, 216/67, 216/71, 118/723 E, 204/298.31, 204/298.33
• US Class Current: 438/710
• CPC Class Codes: H01J 2237/3347 bottom of holes or trenches
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32449 Gas control, e.g. control of the gas flow
• CPC Class Codes: H01J 37/32532 Electrodes
• CPC Class Codes: H01J 37/32724 Temperature

Abstract

The present invention provides a plasma etching system, comprising a process chamber enclosing a plasma, means for evacuating said process chamber, a chuck electrode for supporting a substrate, a shower electrode positioned to face said chuck electrode and provided with a large number of small holes, a power source for applying a plasma voltage between the chuck electrode and said shower electrode, gas supply means communicating with said small holes of the shower electrode for supplying a plasma-forming gas into the process chamber through the small holes, and means for controlling said gas supply means such that said plasma-forming gas flows through said small holes at a mass flow rate of at least 620 kg/m² /hr.

Claims

1. A plasma etching method, comprising the steps of:

mounting a substrate on a chuck electrode disposed in a process chamber;

evacuating said process chamber to set up a reduced pressure within the process chamber;

introducing a process gas into the process chamber such that said gas flows through small holes made in a shower electrode at a mass flow rate of at least 620 kg/m² /hr so as to prevent said process gas from being deposited within said small holes; and

applying a voltage between said shower electrode and said chuck electrode to generate a plasma between these two electrodes, with active species within said plasma acting on said substrate.

2. The method according to claim 1, wherein said shower electrode is cooled during generation of the plasma.

3. The method according to claim 1, wherein said process gas is introduced into said process chamber such that said gas flows through a stepped portion of said small hole made in said shower electrode as a mass flow rate of at least 620 kg/m² /hr.

4. The method according to claim 1, wherein said process gas contains at least two elements selected from the group consisting of C, O, H, F and Ar.

5. The method according to claim 4, wherein said process gas is a mixed gas consisting of a CF₄ gas, a CHF₃ gas, and an Ar gas.

6. The method according to claim 1, wherein said process chamber is evacuated to set up an inner pressure of the process chamber which is not higher than 0.5 Torr.

7. The method according to claim 1, wherein the inner pressure of the process chamber is controlled to fall within a range of between 0.15 Torr and 3.0 Torr during generation of the plasma.

8. The method according to claim 1, wherein said process gas is supplied to flow through the small holes, a said process has a temperature substantially equal to the ambient temperature.

9. The method according to claim 1, wherein the spurting region of the process gas from the small holes is larger than the treating area of said substrate.

10. The method according to claim 1, wherein the spurting region of the process gas from the small holes covers a range of up to 180 mm from the center of the shower electrode.

11. The method according to claim 1, wherein the spurting region of the process gas from the small holes covers a range of up to 180 mm from the center of the shower electrode and not smaller than 120 mm from the center of the shower electrode.

12. The method according to claim 1, wherein the sum of the open areas of said small holes falls within a range of between 100 mm² and 120 mm².

13. An etching method using an etching apparatus comprising a chamber enclosing a plasma, means for evacuating said chamber, a chuck electrode for supporting a substrate, a shower electrode forming a plasma discharge circuit together with said chuck electrode, a power source for applying a plasma voltage between said shower electrode and said chuck electrode, gas supply means for supplying a plasma-generating gas to said chamber, and control means for controlling said gas supply means,

wherein said shower electrode comprises:

a cathode plate positions to face the substrate supported by said chuck electrode;

a cooling plate bonded to said cathode plate for cooling the cathode plate;

a large number of inlet holes made in said cooling plate for guiding said gas supplied from said gas supply means into the chamber; and

a large number of small holes made in said cathode plate to communicate with said inlet holes and positioned to face said chuck electrode, the diameter of said small hole being smaller than that of said inlet hole to form a stepped portion at the communicating portion with the inlet hole; and

the mass flow rate of the plasma-generating gas passing through said stepped portion formed between said small hole and said inlet hole is controlled to be at least 620 kg/m² /hr by said control means to prevent said gas component from being deposited in said stepped portion.