Chemical apparatus and process disinfecting – deodorizing – preser – Chemical reactor – With means applying electromagnetic wave energy or...
Reexamination Certificate
1998-09-10
2001-03-27
Anderson, Bruce C. (Department: 2881)
Chemical apparatus and process disinfecting, deodorizing, preser
Chemical reactor
With means applying electromagnetic wave energy or...
C250S492200, C250S398000, C250S441110
Reexamination Certificate
active
06207117
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a charged particle beam apparatus, such as an electron beam exposure apparatus, used for drawing or transcribing a pattern on a substrate, and more particularly to a charged particle beam apparatus capable of reducing the amount of carbon compounds and a gas supply/exhaustion method employed therein.
In accordance with the development of integration of LSI devices, there are now strict demands for lithography apparatuses to have a higher precision and throughput. At the present stage, electron beam exposure apparatuses used as lithography apparatuses include drawing apparatuses using reticles (masks) and apparatuses for directly drawing patterns on wafers. To secure a sufficient throughput, these apparatuses employ a variable shaped beam (VSB) method or a character projection (CP) method as an exposure method.
When a pattern is drawn by such an electron beam exposure apparatus, beam drift is exemplified as a cause of degrading the drawing precision. How the drawing precision is degraded by the beam drift will be described using a shaping deflector as an example.
As shown
FIG. 2
, the shaping deflector is arranged between a first shaping aperture and a second shaping aperture. A deflector plate incorporated in the shaping deflector is made of, for example, Au, Pt, or Al coated with an Au thin film. These materials are used because it is important to keep the deflector plate surface stable. The shaping deflector controls a beam so that an image having passed through the first shaping aperture can be projected onto a predetermined portion of the second shaping aperture. The cause of occurrence of beam drift in the shaping deflector lies in the fact that the image having passed through the first shaping aperture will not be able to be projected onto the predetermined portion of the second shaping aperture with the lapse of time. The beam drift which occurs in the shaping deflector will be referred to as “shaping beam drift”.
When shaping beam drift has occurred, the shape and size of the shaping beam will vary with the lapse of time. Accordingly, a shaping beam image of a desired shape and size will not be able to be obtained with the lapse of time, thereby degrading the precision of a drawn pattern.
Moreover, such beam drift may also occur in a deflector for positioning a beam on a desired portion of a sample.
The beam drift is mainly caused by an increase in the charge of substances which is accumulated on deflector electrodes incorporated in the deflector, or on components contained in a beam column near the deflector electrodes. Where non-conductive substances exist near the beam path, they are charged up when radiated with a beam, thereby changing the path of the beam. These non-conductive substances whose charge will increase due to the beam radiation are mainly carbon compounds.
Accumulation of the carbon compounds will appear when residual gases of carbon compounds adsorbed on surface portions of components in the beam column are excited and decomposed by low energy electrons such as secondary electrons.
Part of the residual gases of the carbon compounds consists of a gas which remains in the beam column even after exhaustion of the barrel. Further, a greater part of the residual gases consists of the gas of a carbon compound (mainly as the material of a solvent of a resist) which evaporates from the resist during exposure. This gas is generated whenever the exposure is performed. Accordingly, a great amount of carbon compounds is accumulated upon the components such as the deflector electrodes of the deflector contained in the beam column, thereby causing beam drift and hence serious degradation of drawing accuracy.
BRIEF SUMMARY OF THE INVENTION
It is the object of the invention to provide a charged-particle beam apparatus of a high and reliable drawing accuracy, and a method of supplying an oxidizing gas to the apparatus and exhausting the gas therefrom.
To attain the object, the invention provides a charged-particle beam apparatus comprising:
a beam apparatus main body including: a beam column having a beam source section which contains a beam source for generating a charged-particle beam, and a beam column main body having a deflector electrode section for deflecting the beam generated from the beam source; and a sample chamber connected to the beam column and containing a sample to be radiated with the beam deflected by the deflector electrode section of the beam column; and
a catalyst member provided in the at least one of the beam column and the sample chamber, in which carbon compounds are generated, the catalytic material accelerating decomposition of the carbon compounds by oxidation.
Further, in a beam apparatus main body including: a beam column having a beam source section which contains a beam source for generating a charged-particle beam, and a beam column main body having a deflector electrode section for deflecting the beam generated from the beam source; and a sample chamber connected to the beam column and containing a sample to be radiated with the beam deflected by the deflector electrode section of the beam column;
the deflector electrodes each have a precious metal catalyst.
According to another aspect of the invention, there is provided a method of supplying an oxidizing gas into and exhausting the gas from a charged-particle beam apparatus including: a beam column having a beam source section which contains a beam source for generating a charged-particle beam, and a deflector electrode section for deflecting the beam generated from the beam source; a sample chamber connected to the beam column and containing a sample to be radiated with the beam deflected by the deflector electrode section of the beam column; and a catalyst member provided in the at least one of the beam column and the sample chamber, in which carbon compounds are generated, the catalytic material accelerating decomposition of the carbon compounds by oxidation, comprising the steps of:
supplying an oxidizing gas into at least one of the beam column and the sample chamber, with the beam source section isolated from the beam column; and
exhausting the oxidizing gas from the at least of the beam column and the sample chamber.
In general, precious metals such as platinum and elements of the platinum group are known as catalysts for accelerating decomposition of carbon compound gases by oxidation. For example, a substance consisting of platinum fine particles called “platinum black” or porous platinum called “platinum sponge” have large effective surface areas, and hence can adsorb a great amount of carbon compound gases. Then, the porous platinum serves as a catalyst to accelerate decomposition-by-oxidation of the adsorbed carbon compound gases, whereby the carbon compound gases are quickly converted into water and, for example, CO
2
.
As stated above, a porous or granular precious metal catalyst (e.g. platinum) is contained in the sample chamber to effectively adsorb a carbon compound gas generated from a resist during exposure, then to accelerate, by its catalytic function, decomposition of the carbon compound using an oxidizing substance (oxygen, ozone, etc.). The products resulting from the decomposition are exhausted to the outside of the apparatus by vacuum exhaustion. As a result, the amount of the carbon compound flowing into the beam column can be significantly reduced.
Moreover, the deflector electrodes of the beam column can be formed to contain a granular or porous precious metal catalyst (e.g. platinum). This catalyst adsorbs a carbon compound gas generated from a resist during exposure and contaminating the surfaces of the electrodes, and accelerates, by its catalytic function, decomposition-by-oxidation of the carbon compound. The products resulting from the decomposition are exhausted to the outside of the apparatus by vacuum exhaustion.
The above-described structure prevents accumulation of carbon compounds on, for example, the deflector electrodes of a deflector, thereby suppressing a beam drift caused by charge
Ogasawara Munehiro
Takamatsu Jun
Anderson Bruce C.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
Wells Nikita
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