Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
1999-02-05
2001-12-25
Dang, Thi (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C118S7230MA, C118S7230MP, C204S298370, C204S298380
Reexamination Certificate
active
06332947
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus and to a plasma processing method using the same suitable for uniform plasma processing over a large area, which works specifically under a low gas pressure in a processing step using plasma such as plasma etching, ion doping, plasma CVD film formation, sputtering film formation, etc. for fabricating semiconductor devices, etc.
As prior art techniques for this kind of plasma processing apparatuses there are known those reported e.g. in J. Vac. Sci. Technol. B9(1), January/Febuary 1991, p.26~p.28. In this paper it is described that magnetic field similar to that formed by a solenoid coil used as means for generating a first static magnetic field described ibid. p.29~p.33 can be realized by means of permanent magnets. In this example permanent magnets for replacing the solenoid coil magnetic field should be huge.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a microwave plasma processing apparatus capable of effecting plasma processing in a uniform high density plasma having a large extent by decreasing the size of the permanent magnets.
Another object of the present invention is to provide a microwave plasma processing apparatus capable of effecting plasma processing in a uniform plasma having a large extent, on which influences of the magnetic field are suppressed.
Still another object of the present invention is to provide a microwave plasma processing apparatus capable of generating a uniform high density plasma having a large extent for plasma processing.
The prior art techniques have problems described below, because the permanent magnets, which are the means for generating the first static magnetic field, are huge.
That is, at first, they have a problem that fabrication cost of the permanent magnets is correspondingly high. Attenuation rate of magnetic field at places distant from the permanent magnets is small and therefore strong magnetic field remains on a matter which is to be processed. For this reason, there is a problem that these techniques are unsuitable for processing matters sensitive to magnetic field, e.g. magnetic films, etc. Further, since in the magnetic field generated by huge permanent magnets attenuation in strength is small and thus spatial magnetic field gradient is small, spatial variations in propagation and absorption of microwave are great, which gives rise to instability of discharge.
In general, from a point of view of quality of plasma, in order to make plasma uniform in a large extent, plasma generated in a strong magnetic field produced by the first static magnetic field generating means is diffused into a weak magnetic field region enclosed by a superficial magnetic field produced by second a static magnetic field generating means. Therefore a major part of generated ions traverse the magnetic field and kinetic energy of ions accelerated by the gradient in plasma potential is transformed into thermal energy, which increases ion temperature. Further, separation of different kinds of ions takes place due to the difference in cyclotron radius in the magnetic field and in addition radicals generated at the same time as the plasma are also not made uniform by action of the electromagnetic field, which gives rise to still another problem that plasma processing is made non-uniform.
By the present invention a microwave plasma processing apparatus is provided, which can generate a uniform high density plasma having a large extent at a low cost by decreasing the size of the permanent magnets, in view of the problems of the prior art techniques, and which can subject matters to be processed to uniform plasma processing over a large area by using plasma thus generated, suppressing influences of magnetic field thereon.
The present invention is characterized in that it comprises at least one waveguide portion for introducing microwave; an electron heating space chamber portion formed on a downstream side with respect to a dielectric body in the waveguide portion; a plasma generating space chamber portion coupled to the electron heating space chamber portion; first static magnetic field generating means surrounding the electron heating space chamber portion by means of permanent magnets, which produce a strong magnetic field exceeding an electron cyclotron resonance magnetic field strength along a transmission direction of the microwave in the electron heating space chamber portion and in a microwave leading-out portion of the dielectric body, and which form a cusped magnetic field, which falls steeply from a position of electron cyclotron resonance magnetic field strength to a boundary portion between the electron heating space chamber portion and the plasma generating space chamber portion and a direction of which is reversed to that of the strong magnetic field with decreasing distance from the boundary portion between the electron heating space chamber portion and the plasma generating space chamber portion to the plasma generating space chamber portion; second static magnetic field generating means consisting of permanent magnets arranged around the plasma generating space chamber portion, every two of which have polarities opposite to each other; and means for holding a matter to be processed opposite to the plasma generating space chamber portion.
It is characterized further in that it comprises a counterplate disposed in front of the plasma generating space chamber portion, opposite to the matter to be processed; and means for applying a bias voltage to the counterplate.
According to the present invention, when the waveguide portion is fed with microwave, since the electron heating space chamber portion is formed on the downstream side with respect to the dielectric body in the waveguide portion and that space chamber portion is disposed within the waveguide portion having a small width in the direction of microwave electric field, it is possible to introduce microwaves having a strong electric field into the electron heating space chamber portion. Further, since microwaves are introduced into the electron heating space chamber portion from the strong magnetic field side having a strength exceeding an electron cyclotron resonance magnetic field strength, even if a plasma having a density higher than a cut-off density as plasma is produced, it is possible to have microwave reach an electron cyclotron resonance layer with a high efficiency. Still further, since the width of the electron heating space chamber portion is so small as described above, the size of the permanent magnets acting as the first static magnetic field generating means arranged around it can be reduced.
In addition, since the permanent magnets acting as the first static magnetic field generating means form a magnetic field having a great gradient in the neighborhood of the electron cyclotron resonance magnetic field strength in the electron heating space chamber portion, even if a magnetic field strength at which microwaves are easily absorbed varies, depending on the state of plasma, it is possible to suppress spatial variations of microwave absorption positions to a value sufficiently small with respect to microwave wavelength. Consequently it is possible to eliminate instability factors concerning propagation and absorption of microwave as far as possible and therefore to feed surely and stably the electron heating space chamber portion with a microwave having a high electric field. In this way, in the electron heating space chamber portion, it is possible to have electrons absorb almost all microwave to heat them and to obtain high energy electrons.
At this time, since the permanent magnets acting as the first static magnetic field generating means form a cusped magnetic field, the magnetic field direction of which is reversed on the further downstream side from the boundary portion between the electron heating space chamber portion and the plasma generating space chamber portion as described above, electrons close to the axis of the electron heating space ch
Hashimoto Isao
Ichimura Satoshi
Sato Tadashi
Dang Thi
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
LandOfFree
Plasma processing apparatus and plasma processing method... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Plasma processing apparatus and plasma processing method..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plasma processing apparatus and plasma processing method... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2564615