Plasma treatment method and apparatus

• US 20040026372A1
• Filed: 02/14/2003
• Published: 02/12/2004
• Est. Priority Date: 04/20/1994
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Nishikawa, Hiroshi, Takenaka, Hiroto
• Granted Patent: US 6,991,701 B2
• Time in Patent Office: Days
• US Class Current: 216/71
• CPC Class Codes: C23C 16/4405 Cleaning of reactor or parts inside the reactor by using reactive gases
• CPC Class Codes: C23C 16/4407 Cleaning of reactor or reactor parts by using wet or mechanical methods
• CPC Class Codes: C23C 16/4483 using a porous body
• CPC Class Codes: C23C 16/4485 by evaporation without using carrier gas in contact with the source material C23C16/4486 takes precedence
• CPC Class Codes: C23C 16/45565 Shower nozzles
• CPC Class Codes: C23C 16/4557 Heated nozzles
• CPC Class Codes: C23C 16/5096 Flat-bed apparatus
• CPC Class Codes: C23C 16/517 using a combination of discharges covered by two or more of groups C23C16/503 - C23C16/515
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32155 Frequency modulation
• CPC Class Codes: H01J 37/32165 Plural frequencies
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01J 37/32963 End-point detection
• CPC Class Codes: Y10S 156/916 Differential etching apparatus including chamber cleaning means or shield for preventing deposits

Abstract

A plasma treatment method comprising exhausting a process chamber so as to decompress the process chamber, mounting a wafer on a suscepter, supplying a process gas to the wafer through a shower electrode, applying high frequency power, which has a first frequency f₁ lower than an inherent lower ion transit frequencies of the process gas, to the suscepter, and applying high frequency power, which has a second frequency f₂ higher than an inherent upper ion transit frequencies of the process gas, whereby a plasma is generated in the process chamber and activated species influence the wafer.

Claims

1. A plasma treatment method of plasma-treating a substrate, which is to be treated, under decompressed atmosphere comprising, the steps of:

exhausting a process chamber so as to decompress the process chamber;

mounting the substrate, which is to be treated, on a lower electrode;

supplying a process gas to the substrate on the lower electrode through an upper electrode;

applying high frequency power, which has a first frequency f₁ lower than an inherent lower ion transit frequencies of said process gas, to the lower electrode; and

applying high frequency power, which has a second frequency f₂ higher than an inherent upper ion transit frequencies of said process gas, to the upper electrode, whereby a plasma is generated in the process chamber and activated species influence the substrate to be treated.

2. The plasma treatment method according to claim 1, wherein said process gas is formed of a plurality of component gases, said first frequency f₁ is the lowest of the inherent lower ion transit frequencies of said component gases, and said second frequency f₂ is the highest of the inherent higher ion transit frequencies of said composite gases.

3. The plasma treatment method according to claim 1, wherein the first frequency f₁ is lower than the second frequency f₂.

4. The plasma treatment method according to claim 1, wherein the first frequency f₁ is set lower than 1 MHz, and the second frequency f₂ is set higher than 10 MHz.

5. The plasma treatment method according to claim 4, wherein the first frequency f₁ is in a range of 100 kHz-1 MHz, and the second frequency f₂ in a range of 10 MHz-100 MHz.

6. The plasma treatment method according to claim 1, wherein high frequency components of said first frequency f₁ are removed from said high frequency power applied to the upper electrode.

7. The plasma treatment method according to claim 1, wherein high frequency components of said second frequency f₂ are removed from high frequency power entering into a power supply circuit through plasma, a power supply circuit serving to apply said high frequency power, which has the first frequency f₁, to the lower electrode.

8. The plasma treatment method according to claim 1, further comprising the steps of, applying high frequency power, which has a frequency same as the first frequency f₁, and which is amplitude-modulated, to the upper electrode.

9. The plasma treatment method according to claim 1, further comprising the steps of, applying high frequency power, which has a frequency same as the second frequency f₂ and which is amplitude-modulated, to the lower electrode.

10. The plasma treatment method according to claim 8, wherein amplitude modulation is carried out to form one of sine, triangular, rectangular and sawtooth waveforms or their composite waveform.

11. The plasma treatment method according to claim 9, wherein amplitude modulation is carried out to form one of sine, triangular, rectangular and sawtooth waveforms or their composite waveform.

12. The plasma treatment method according to claim 1, wherein one or more gases selected from the group consisting of CF₄, C₄F₈, CHF₃, Ar, O₂ and CO gases are used as the process gas.

13. The plasma treatment method according to claim 1, further comprising the steps of, introducing one or more cleaning gases selected from the group consisting of ClF₃, CF₄ and NF₃ gases into the process chamber while keeping a ring and/or a baffle plate attached to the lower electrode when plasma is stopped;

and dry cleaning the ring and/or the baffle plate.

14. The plasma treatment method according to claim 1, further comprising the steps of, detaching the ring and/or the baffle plate from the lower electrode when plasma is stopped;

and dry cleaning the ring and/or the baffle plate using at least one or more cleaning gases selected from the group consisting of ClF₃, CF₄ and NF₃.

15. The plasma treatment method according to claim 1, further comprising the steps of, detaching the ring and/or the baffle plate from the lower electrode when plasma is stopped;

and wet cleaning the ring and/or the baffle plate using at least one cleaning solution selected from a group of isopropylalcohol, water and fluorophosphoric acid.

16. The plasma treatment method according to claim 1, further comprising the steps of counting the number of particles adhering to the substrate which has been treated in the process chamber;

and cleaning the ring and/or the baffle plate while keeping plasma stopped when the number of particles adhering becomes larger than a predetermined value.

17. The plasma treatment method according to claim 1, further comprising the steps of, counting the number of particles scattering in atmosphere exhausted from a treatment apparatus and/or at least in one or more areas in an exhaust pipe;

and cleaning the ring and/or the baffle plate while keeping plasma stopped when the number of particles becomes larger than a predetermined value.

18. A plasma treatment apparatus for plasma-treating a substrate, which is to be treated, under decompressed atmosphere comprising:

a chamber earthed;

means for exhausting the chamber;

a lower electrode on which the substrate to be treated is mounted;

an upper electrode arranged in the chamber to oppose to the lower electrode;

means for supplying process gas to the substrate on the lower electrode through the upper electrode;

a first power supply connected to the lower electrode through a first matching circuit to apply high frequency power, which has a first frequency f₁ lower than an inherent lower ion transit frequency of the process gas, to the lower electrode;

a second power supply connected to the upper electrode through a second matching circuit to apply high frequency power, which has a second frequency f₂ higher than an inherent upper ion transit frequency of the process gas, to the upper electrode;

first filter means for removing high frequency components of the second frequency f₂ from the high frequency power applied to the lower electrode; and

second filter means for removing high frequency components of the first frequency f₁ from the high frequency power applied to the upper electrode.

19. The plasma treatment apparatus according to claim 18, wherein the first filter means is connected to a first circuit, which connects a first matching circuit to the lower electrode, at an end thereof and the first circuit includes a first earthed capacitor at the other end thereof;

and the second filter means is connected to a second circuit, which connects the first matching circuit to the upper electrode, at an end thereof and the second circuit includes, at the other end thereof, a second earthed capacitor and an induction coil connected in series to the second capacitor.

20. The plasma treatment apparatus according to claim 18, wherein said first filter means has an impedance larger than several kΩ

relative to the high frequency power having the first frequency f₁ and an impedance smaller than several Ω

relative to the high frequency power having the second frequency f₂; and

said second filter means has an impedance smaller than several Ω

relative to the high frequency power having the first frequency f₁ and an impedance larger than several kΩ

relative to the high frequency power having the second frequency f₂.

22. The plasma treatment apparatus according to claim 18, wherein said exhaust means exhausts the chamber to an internal pressure of 10-250 mTorr.

23. The plasma treatment apparatus according to claim 18, further comprising a ring freely detachably attached to the outer circumference of the lower electrode to cause reaction products created by heat or plasma to adhere not to the lower electrode but to the ring.

24. The plasma treatment apparatus according to claim 18, further comprising the ring freely detachably attached to the outer circumference of the lower electrode to cause reaction products created by heat or plasma to adhere not to the lower electrode but to the ring;

and lifter means for moving the lower electrode up and down together with the ring.

25. The plasma treatment apparatus according to claim 18, wherein the chamber has an opening through which the substrate to be treated is carried in and out, and the ring is moved up and down between the upper end and the lower end of said opening by the lifter means.

26. The plasma treatment apparatus according to claim 25, further comprising a baffle plate attached to the outer circumference of the ring and positioned higher than the upper end of said chamber opening, when the ring is lifted, to shield the chamber opening from plasma atmosphere.

27. The plasma treatment apparatus according to claim 26, further comprising an exhaust opening formed in that portion of the chamber side wall which is lower than the top of the lower electrode;

and holes formed in the baffle plate to adjust or rectify the flow of the process gas, wherein each hole in the baffle plate is tilted relative to the vertical axis to cause the process gas, which has passed through the holes, to flow in a direction reverse to the direction in which gas is exhausted by a rotary pump.

28. The plasma treatment apparatus according to claim 26, wherein the baffle member comprises plural plates in which holes each having a substantially same pitch are formed, and they are placed one upon the others to shift their corresponding holes a little to form a step-like hole.

29. The plasma treatment apparatus according to claim 18, further comprising a cover member freely detachably attached to the upper electrode to cover a peripheral portion thereof so as to prevent reaction products from adhering to the upper electrode.

30. The plasma treatment apparatus according to claim 29, wherein the upper electrode has first engaged recesses or projections formed in or on the outer circumference thereof, the cover member has second engaging projections or recesses formed on or in an inner circumference thereof and the cover member is made of elastic material, and the second engaging projections or recesses are engaged with the first engaged recesses or projections while elastically deforming the cover member.

31. The plasma treatment apparatus according to claim 29, wherein said cover member includes a wall member to cover an upper inner wall of the chamber.

32. The plasma treatment apparatus according to claim 18, wherein an insulating layer, 3 mm or more thick, is formed at least on the inner side wall of the chamber.

33. The plasma treatment apparatus according to claim 18, further comprising a vaporizer for vaporizing liquid material from which the process gas is created, wherein said vaporizer includes a housing provided with a liquid material inlet communicated with a liquid material supply supply and with a process gas outlet communicated with the chamber, and a porous conductive heating unit arranged in the housing.

34. The plasma treatment apparatus according to claim 33, wherein said vaporizer includes vibrators to vibrate the porous conductive heating unit.

35. The plasma treatment apparatus according to claim 33, wherein said vaporizer is arranged adjacent to a process gas introducing section of the chamber.

36. The plasma treatment apparatus according to claim 33, wherein said vaporizer is made integral to the process gas introducing section of the chamber.

37. The plasma treatment apparatus according to claim 33, further comprising a bypass arranged between the vaporizer and the process gas introducing section wherein the process gas outlet of the vaporizer is selectively communicated with one of the bypass and the process gas introducing section.

38. The plasma treatment apparatus according to claim 33, wherein said porous conductive heating unit is a sintered ceramics.

39. The plasma treatment apparatus according to claim 33, wherein a passage through which liquid material flows is formed in the porous conductive heating unit.

40. The plasma treatment apparatus according to claim 33, wherein a second gas introducing opening is formed downstream the vaporizer and a gas mixing passage through which plural gases are mixed extends downstream the second gas introducing opening.

21. A plasma treatment apparatus for plasma-treating a substrate, which is to be treated, under decompressed atmosphere comprising:

a chamber earthed;

exhaust means for exhausting the chamber;

a lower electrode on which the substrate is mounted;

an upper electrode arranged in the chamber to oppose to the lower electrode;

means for supplying process gas to the substrate on the lower electrode through the upper electrode;

a first power supply connected to the lower electrode through a first matching circuit to apply high frequency power, which has a first frequency f₁ lower than an inherent lower ion transit frequency of the process gas, to the lower electrode;

a second power supply connected to the upper electrode through a second matching circuit to apply high frequency power, which has a second frequency f₂ higher than an inherent upper ion transit frequency of the process gas, to the upper electrode; and

an amplitude modulator circuit connected to the first and second power supplies to modulate the amplitude of the high frequency power having the first frequency f₁ to apply amplitude-modulated high frequency to the upper electrode.