Radiant energy – Inspection of solids or liquids by charged particles – Analyte supports
Reexamination Certificate
2001-12-05
2004-06-01
Lee, John P. (Department: 2881)
Radiant energy
Inspection of solids or liquids by charged particles
Analyte supports
Reexamination Certificate
active
06744054
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a sample chamber which is maintained in high vacuum around a sample through evacuation therefrom and a circuit pattern forming apparatus using the same.
2. Conventional Art
In an apparatus which forms or inspects circuit patterns such as for a semiconductor device and a magnetic head and circuit patterns such as masks and reticles for forming circuit patterns for a semiconductor device, these circuit patterns are formed and inspected through irradiation of charged particles onto samples. In such instance, it is unavoidable that the charged particles, in particular electron beams have to be used in vacuum. For this reason, the circuit pattern formation and inspection is performed while placing samples in a gas evacuated vacuum chamber.
Hereinbelow, an electron beam pattern drawing apparatus which draws a circuit pattern on a sample by making use of electron beams will be explained taking up as an example.
An electron beam pattern drawing apparatus is one in which through generation of electron beams under a super high vacuum environment and scanning therewith LSI patterns are formed on a semiconductor substrate or a glass substrate called as a mask which is used for an exposure apparatus such as a stepper.
FIG. 12
shows a structure of a conventional electron beam pattern drawing apparatus. As shown in
FIG. 12
, electron beams
3
emitted from an electron gun
2
in a column
1
are shaped into a rectangular shape by a diaphragm
4
and a shaping deflector
5
, and are image-formed on a desired position of a sample
8
by an electron lens
6
and a deflector
7
. The sample
8
is fixed on an XY stage
9
through a sample holder or directly.
The position of the sample
8
on the XY stage
9
is managed by measuring the distance between a bar mirror
13
and a laser interference meter
12
, and through feed forwarding the obtained information to the deflector
7
a highly accurate circuit pattern can be formed. Inside of a sample chamber
10
is kept in a high vacuum environment by a sample chamber use vacuum pump
17
to thereby prevent energy loss of the electron beams.
Now, a transportation route of the sample
8
will be explained.
The sample
8
is transported by a transportation device
16
in a load chamber
14
located adjacent to the sample chamber
10
from external in atmospheric circumstance into the load chamber
14
, which is preliminarily gas-evacuated from atmospheric state into vacuum state a load chamber use vacuum pump
18
. When the vacuum in the load chamber
14
reaches at the same level as that in sample chamber
10
, a valve
15
is opened and the sample
8
is transported onto the XY stage
9
. After completing pattern drawing, a reverse route is traced, in that inside of the load chamber
14
is returned from vacuum into atmospheric circumstance and thereafter, the sample
8
is transported into outside. With the above series of operations, the transportation of the sample can be carried out while keeping the sample chamber
10
in vacuum state, thereby, an improvement of throughput is achieved.
During drawing of a circuit pattern by an electron beam pattern drawing apparatus, it is necessary to keep the electron beam passage in high vacuum so as to prevent energy loss of the electron beams as has been referred to above, however, there were the following problems in conventional apparatuses.
(1) It was required to evacuate the entire sample chamber in high vacuum, therefore, a vacuum pump of high performance as well as large capacity was indispensable.
(2) Once the inside of the sample chamber was placed in atmospheric circumstance due to such as maintenance and failure thereof, it took a few hours to restore the circumstance into high vacuum which reduced available time of the apparatus.
(3) In order to keep the inside of the sample chamber in high vacuum, parts used inside the sample chamber were restricted to inactive materials and, in particular, many kinds of resins and lubricants could not be used.
(4) Mechanism which use gas such as air could not be mounted in the sample chamber.
In order to overcome the above problems, until now apparatuses which keep around the passage of the electron beams and a part of the stage in vacuum state are, for example, disclosed in JP-A-1-128525 (1989), JP-A-8-17709 (1996) and JP-B-3-23631 (1991). These apparatuses are provided with a flange
60
which includes a function of vacuum evacuation at the bottom face of the column
1
as shown in FIG.
13
and perform differential evacuation while managing the gap between the sample
8
and the flange
60
.
In the flange
60
apertures
60
A for vacuum evacuation are formed which permits differential evacuation with the circumference of the stage
9
.
However, in the apparatuses as disclosed such as in JP-A-1-128525 (1989), JP-A-8-17709 (1996) and JP-B-3-23631 (1991), although it is possible to keep the electron beam passage in vacuum upto the sample
8
regardless to the atmosphere of the stage
9
, a pressure difference due to a local differential evacuation is caused on the sample
8
. Accordingly, at a top table
21
the region of the pressure difference varies in accordance with the displacement of the sample
8
which possibly causes attitude change of the top table
21
and deformation thereof.
Further, when performing pattern drawing (exposure, inspection) over the entire surface of a sample, because of the existence of a gap between edges of the sample
8
and a sample holding mechanism or the top table
21
, amount of gas which flows in through the gap increases which makes difficult to obtain a stable vacuum. Namely, in order to keep a stable differential evacuation condition it is necessary to prevent the apertures
60
A from protruding beyond the outer circumference of the sample
8
as shown in FIG.
13
. As a result, in a range of distance R from outer circumference of the sample
8
toward the center thereof a pattern drawing can not be performed, thereby, a possible pattern drawing range around the outer circumference of the sample is wasted and a yielding of the sample
8
with regard to pattern drawing range is reduced.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an evacuation use sample chamber which performs a stable evacuation and keeps around a sample at a predetermined high vacuum and a circuit pattern forming apparatus which permits a highly accurate pattern drawing over the entire region of the sample.
In order to achieve the above object, an evacuation use sample chamber according to the present invention is characterized, in that the evacuation use sample chamber is constituted by a table which is provided with a recessed portion disposed in a sample chamber main body and for mounting a sample and a groove portion surrounding the recessed portion; a stage which holds the table and is displaceable in front and back, right and left and up and down directions together with the table; a sample chamber cover which covers above the sample chamber main body including the table; and an evacuation use pipe which communicates with the groove portion and evacuates gas between the bottom face of the sample chamber cover and the top face of the table including the sample.
More specifically, the present invention provides the following sample chamber and device.
The present invention provides an evacuation use sample chamber which is characterized by comprising, a sample chamber main body; a table which is provided with a recessed portion disposed in the sample chamber main body and for mounting a sample and a groove portion surrounding the recessed portion; a stage which holds the table and is displaceable in front and back, right and left and up and down directions together with the table; a sample chamber cover which covers above the sample chamber main body including the table; and an evacuation use pipe which communicates with the groove portion and evacuates gas between the bottom face of the sample chamber cover and the top face of th
Fukushima Yoshimasa
Inoue Mitsuru
Mizuochi Masaki
Hitachi , Ltd.
Kalivoda Christopher M.
Kenyon & Kenyon
Lee John P.
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