Plasma processing system and plasma processing method

• US 6,245,190 B1
• Filed: 03/26/1998
• Issued: 06/12/2001
• Est. Priority Date: 03/26/1997
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Koizumi, Makoto, Shirayone, Shigeru, Tanaka, Junʼichi, Sasaki, Ichiro, Watanabe, Katsuya, Masuda, Toshio, Kaji, Tetsunori, Otsubo, Toru, Mitani, Katsuhiko, Fukumoto, Hideshi
• Primary Examiner(s): Warden, Sr., Robert J.
• Assistant Examiner(s): Olsen, Kaj K.
• Application Number:
  US09/048,075
• Time in Patent Office: 1,174 Days
• Field of Search: 156/345.P, 156/345.MG, 156/345, 204/298.16, 204/298.37, 216/70, 118/723.R, 118/723.MR, 118/723.MA
• US Class Current: 156/345.46
• 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 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32165 Plural frequencies
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• CPC Class Codes: H01J 37/3266 Magnetic control means
• CPC Class Codes: H01J 37/32678 Electron cyclotron resonance

Abstract

A plasma processing apparatus and a method therefor which can achieve a preferred process rate, a fine pattern process capability, a selectivity and uniformity of processing at the same time compatibly for a large size wafer, which effects are achieved by controlling the plasma state and the dissociation state of etching gas through control of the electron resonance through application of a magnetic field thereto. A high frequency power at 20-300 MHz is applied across a pair of electrodes in a vacuum process chamber, and a magnetic field is formed parallel to the plane of the electrodes in the space between the electrodes. By controlling the intensity of the magnetic field in a range of 100 gauss or smaller, formation of electron cyclotron resonance and electron sheath resonance occurring from interaction between the electrical field and the magnetic field in the electrode sheath portion is controlled. Thereby, the plasma state, i.e., the electron density, electron energy distribution and dissociation state of the process gas in the plasma, can be controlled. The magnetic field is generated by a plurality of coils, an outer shield, and pendant yoke to form magnetic field parallel to the plane of the electrodes in the space between the upper and the bottom electrodes.

Claims

1. A plasma process apparatus comprising a vacuum process chamber, a plasma generation means containing a pair of electrodes placed at the top and bottom inside of said vacuum process chamber, a sample table having a sample placement surface on which the sample to be process is placed, said table being one of said pair of electrodes, and a vacuum exhaust means that evacuates said vacuum process chamber, wherein said top electrode has a bottom surface which is flat and forms part of said process chamber,

a high frequency power source that applies high frequency power at 40 MHZ to 150 MHZ between said pair of electrodes and provides an electric field, a magnetic field forming means for forming an electron sheath resonance (ESR), said magnetic field forming means generating one of a low frequency alternating magnetic field and a static magnetic field having an intensity controllable to a value in the range of 2 gauss to 60 gauss, wherein said magnetic field which is generated is formed in a region immediately below said top electrode, is concentrated on the region and is formed substantially parallel to the bottom surface of said top electrode,

said magnetic field forming means containing a plural number of pairs of electromagnetic coils placed on a left and right exterior side of said process chamber and a current control means for controlling the current passed through said electromagnetic coils so that said electron sheath resonance (ESR) is formed at an electron resonance magnetic field intensity due to mutual effect of the magnetic field generated by said magnetic field forming means and the electric field in a sheath part of said plasma over substantially the entire surface in the neighborhood of the sheath of the plasma at the bottom surface of said top electrode, the condition of said plasma being controlled by controlling said electron resonance through the control of the current flowing through said electromagnetic coils of said magnetic field forming means.

2. A plasma process apparatus according to claim 1, wherein electron resonance region is formed by the electron sheath resonance (ESR) which occurs at a magnetic field intensity Bs which is defined by Bs (gauss)=½

×

0.357×

f (MHz), where f is a frequency of said high frequency power supply.

3. A plasma process apparatus according to claim 1, wherein a spacing between said pair of electrodes is 15 mm to 100 mm.

4. A plasma process apparatus according to claim 1, wherein said electrodes are a pair of parallel flat plate electrodes placed at the top and bottom, and a region of generating said electron resonance is formed over substantially the entire surface of the sheath on the bottom surface of the top electrode plate by making the position of forming the parallel magnetic field come on the bottom surface of the top electrode plate.

5. A plasma processing method for a plasma process apparatus having a vacuum process chamber, a plasma generation means containing a pair of electrodes placed at the top and bottom inside of said vacuum process chamber, a sample table having a sample placement surface on which the sample to be processed is placed said table being one of said pair of electrodes, and a vacuum exhaust means that evacuates said vacuum process chamber, said method comprising the steps of:

applying a high frequency power at 20 MHz to 300 MHz from a high frequency power generation means between said pair of electrodes to generate an electric field;

generating one of a low frequency alternating magnetic field and a static magnetic field having an intensity controllable to a value of no greater than 100 gauss with said magnetic field being at right angles to the electric field generated by said high frequency power source at the surface coming into contact with the plasma of at least one of said pair of electrodes;

forming electron sheath resonance (ESR) at the electron resonance magnetic field intensity due to mutual effect of said magnetic field and said electric field at a position that extends over substantially the entire surface in the neighborhood of the surface coming into contact with the plasma at at least one of said pair of electrodes; and

controlling at least one of plasma density, electron energy distribution in the plasma, and the condition of dissociation of the process gas by controlling said electron resonance using said magnetic field forming means.

6. A method of plasma processing of samples according to claim 5, wherein a spacing between said pair of electrodes is 15 mm to 100 mm, and a magnetic field from said magnetic field forming means and that can cause electron resonance is applied in a direction substantially parallel to the electrode surface of said pair of electrodes, the extent of said electron resonance being controlled by varying the intensity of said magnetic field.

7. A method of plasma process of samples according to claim 5, wherein a spacing between said pair of electrodes is 15 mm to 100 mm, and controlling constituent ratios of different radicals in a process gas by forming a magnetic field at an interface section between said pair of electrodes with said magnetic field being substantially parallel to said sheath, and by utilizing both resonances of said ESR and said ECR-S that are generated by varying the intensity of said magnetic field.

8. A method of plasma processing of samples according to claim 5, wherein the step of applying a high frequency power applies high frequency power at 40 MHz to 150 MHz between said pair of electrodes, said top electrode having a bottom surface which is flat and forms part of said process chamber, said magnetic field which is generated being intensity controllable to a value in the range of 2 Gauss to 60 Gauss and said magnetic field being formed in a region immediately below said top electrode, being concentrated on the region and being formed substantially parallel to the bottom surface of said top electrode.

9. A method of plasma processing of samples according to claim 5, wherein the step of forming the electrode sheath resonance (ESR) is formed at a magnetic field intensity Bs which is defined by Bs (Gauss)=½

×

0.357×

f (MHC), where f is a frequency of said high frequency power supply.

10. A method of plasma processing of samples according to claim 5, wherein said pair of electrodes are a pair of parallel flat plate electrodes placed at the top and bottom and said electron sheath resonance (ESR) is formed over substantially the entire surface of the sheath on the bottom surface of said top electrode plate by making the position of forming the parallel magnetic field come on the bottom surface of said top electrode plate.