Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
1999-03-02
2002-03-12
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S709000, C438S710000, C438S712000, C438S714000
Reexamination Certificate
active
06355570
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to semiconductor manufacturing methods, plasma processing methods and plasma processing apparatuses for increasing the yield of material to be processed such as a semiconductor substrate by in-situ (on-the-spot) measuring sub-micron foreign particles floating in the course of processing in a plasma processing chamber without being affected external disturbances such as plasma emitted light.
Prior arts for monitoring foreign particles floating in a plasma processing chamber are disclosed in several documents. In the following description, prior arts disclosed in Japanese Patent Laid-open Nos. Sho 57-118630, Hei 3-25355, Hei 3-147317, Hei 6-82358 and Hei 6-124902 are referred to as prior arts
1
to
5
respectively.
Prior art
1
cited above introduces a depositing apparatus which comprises a means for radiating parallel lights in a reaction space wherein the parallel lights have a spectrum different from the spectrum of a light self emitted in the reaction space and a means for detecting lights scattered from infinitesimal particles generated in the reaction space due to radiation of the parallel lights.
Prior art
2
cited above introduces an infinitesimal-particle measuring apparatus for measuring floating infinitesimal particles and infinitesimal particles stuck to the surface of a semiconductor substrate for making semiconductor devices by using a scattering phenomenon of laser beams. The infinitesimal-particle measuring apparatus comprises: a laser-beam-phase modulating unit for generating
2
laser beams having equal wavelengths and a difference in phase modulated at a predetermined frequency; an optical system for directing the
2
laser beams to intersect each other in a space containing infinitesimal particles being measured; a light detecting unit for receiving lights scattered by the infinitesimal particles being measured in an area where the
2
laser beams intersect each other and converting the received lights into an electrical signal; and a signal processing unit for extracting a signal component having a frequency equal to the frequency of a phase modulation signal used in the laser-beam-phase modulating unit or a frequency twice the frequency of the phase modulation signal and a difference in phase from the phase modulation signal unchanged with the lapse of time out off the electrical signal representing the scattered lights.
Prior art
3
cited above is a technology for measuring the degree of pollution in a reactor by analyzing scattered lights. The art includes the steps of: a scanning operation by using a radiated coherent light to generate lights scattered in the reactor on the spot; and detecting the lights scattered in the reactor.
Prior art
4
cited above introduces a particle detecting apparatus which comprises: a laser means for generating a laser beam; a scanner means for scanning an area in a reactor chamber of a plasma processing tool including particles to be measured by using the laser beam; a video camera means for generating a video signal representing laser beams scattered by particles in the area; and a means for processing the video signal and displaying an image of the video signal.
Prior art
5
cited above introduces a plasma processing apparatus which comprises: a camera apparatus for observing a plasma generation area in a plasma processing chamber; a data processing unit for obtaining desired information by processing a picture taken by the camera apparatus; an exhaust means for reducing the number of particles by using the information produced by the data processing apparatus; and a control unit for controlling at least one of a process-gas introducing means, a high-frequency-voltage applying means and a purge-gas introducing means.
Referred to as prior art
6
, an infinitesimal-particle measuring apparatus used in control of advanced cleaning processes such as semiconductor manufacturing processes and chemical manufacturing processes is disclosed in Japanese Patent Laid-open No. Sho 63-71633. Used for detecting scattered lights from particles in a liquid sample due to radiation of a laser beam to an infinitesimal area of a container flowing the liquid sample being examined, the infinitesimal-particle measuring apparatus provided by prior art
6
comprises: a means for carrying out intensity modulation on the laser beam at a fixed frequency; and a phase detector for measuring a signal coming from a detector having a frequency equal to the frequency of the intensity modulation.
In the plasma processing apparatus, a substance generated by a reaction occurring in a plasma process is deposited on the surface wall of the plasma processing chamber or an electrode. With the lapse of time, however, such a substance is peeled off, becoming a floating infinitesimal foreign particle. The floating infinitesimal foreign particle is stuck to a material to be processed in the course of plasma processing, resulting in a bad product. In other cases, the floating infinitesimal foreign particle is trapped on a bulk-sheath boundary surface and falls on the material to be processed at the time a plasma discharging phenomenon is terminated at the end of the plasma processing. The foreign particle stuck to the material to be processed gives rise to a poor characteristic and an appearance defect. As a result, such a substance decreases the yield of materials to be processed such as semiconductor substrates.
In the mean time, the degree of integration of circuit patterns created on a material to be processed such as a semiconductor substrate has been becoming higher and higher. In the semiconductor field, for example, the integration of circuit patterns in the DRAM is under way, increasing the capacity of the DRAM to 256 Mbit and even to 1 Gbit. That is to say, the minimum line width of the circuit patterns is in a process of being miniaturized to a size in the range 0.25 to 0.18 &mgr;m. It thus becomes necessary to also measure infinitesimal foreign particles on the order of down to sub-microns which float in the plasma or in an area in proximity to the plasma.
Thus, required in the plasma processing apparatus is a capability of measuring also the infinitesimal foreign particles of the order of down to sub-microns floating in the plasma or in an area in proximity to the plasma without being affected by an external disturbance such as plasma emitted light. Since the plasma emitted light exhibits a continuous wavelength spectrum over a range from a zone beyond the ultraviolet ray to a zone beyond the near-infrared ray, however, it is difficult to separate infinitesimal foreign particles of the order of down to sub-microns floating in the plasma or in an area in proximity to the plasma from the plasma emitted light in order to detect the foreign particles by using the spectrum generated in accordance with prior art
1
.
As described above, in either of prior arts
1
to
5
, there is no consideration of a matter regarding an attempt to separate very weak scattered lights generated by infinitesimal foreign particles on the order of down to sub-microns floating in the plasma or in an area in proximity to the plasma from the plasma emitted light in order to detect the scattered lights.
In addition, in prior art
6
used for measuring the number of particles in a liquid sample flowing to a container, there is also no consideration of a matter regarding an attempt to separate very weak scattered lights generated by infinitesimal foreign particles of the order of down to sub-microns floating in the plasma or in an area in proximity to the plasma from the plasma emitted light in order to detect only the scattered lights.
SUMMARY OF THE INVENTION
It is thus an object of the present invention addressing the problems described above to provide a plasma processing method and a plasma processing apparatus for improving the yield of materials to be processed by enabling real-time monitoring of a state of pollution in a plasma processing chamber through substantial enhancement of the detection sensitivity to dete
Nakano Hiroyuki
Nakata Toshihiko
Ninomiya Takanori
Uto Sachio
Antonelli Terry Stout & Kraus LLP
Deo Duy-Vu
Utech Benjamin L.
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