Electric lamp and discharge devices: systems – Current and/or voltage regulation – Automatic regulation
Reexamination Certificate
2003-05-30
2004-05-25
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Current and/or voltage regulation
Automatic regulation
C315S24100S, C355S081000, C355S067000, C355S069000, C396S166000, C396S108000
Reexamination Certificate
active
06741044
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates to a lamp lighting controlling apparatus and light emitting apparatus used for an exposure apparatus for exposing a substrate such as a display board, print circuit board, semiconductor wafer etc., especially, to a lamp lighting controlling apparatus and a light emitting apparatus for precisely controlling desired accumulated light amount on a work piece or work pieces suitable for sputtering etc.
DESCRIPTION OF RELATED ART
In such an exposure apparatus for exposing a substrate or substrates such as a display board, a print circuit board, a semiconductor wafer etc., a light emitting apparatus for emitting exposure light is provided.
In
FIG. 8
, the structure of such the light emitting apparatus
10
is shown.
As shown in the figure, in a light emitting unit
10
, optical components such as a discharge lamp
1
, e.g. an ultrahigh-pressure mercury lamp, that emits exposure light, a condensing mirror
2
for condensing light from the discharge lamp
1
, a first plane mirror
4
(a reflecting mirror) for reflecting the light from the discharge lamp
1
and the condensing mirror
2
, an integrator lens
5
for making the illumination distribution uniform on a light exposure surface, a second plane mirror
7
(a reflecting mirror) for conducting light to a light outgoing window, and a collimator lens
8
for forming light emitted from the light outgoing window into parallel light.
A shutter mechanism
6
comprises a shutter plate
61
(a douser), a shutter driving unit
62
, and a shutter opening/closing detecting sensor
63
.
The shutter plate
61
is driven by the shutter driving unit
62
, and the light emitting amount (light exposure amount) emitted on the light exposure surface is controlled by inserting the shutter plate
61
in the optical path or removing the plate
61
from the optical path.
A open/close state of the shutter
61
is detected by the shutter opening/closing detecting sensor
63
. The light exposure surface may be a mask surface on which a pattern of circuit etc. is formed or a work surface on which a photosensitive agent is coated and formed.
An illuminometer
11
provided behind the second plane mirror
7
, receives light through a light transmission portion such as a pinhole(s) provided on the second plane mirror
7
. Output of the illuminometer
11
is sent to an accumulated light amount measuring unit
12
.
In the accumulated light amount measuring unit
12
, accumulated light amount is calculated by accumulating light amount measured by the illuminometer
11
.
The lamp lighting controlling apparatus
20
comprises a lamp lighting power source
21
for supplying power to turn on the lamp
1
, and a controlling unit
22
.
The lamp lighting power source
21
has a power supply unit
21
a
and a start-up circuit
21
b
(a starter). The power supply unit
21
a
converts AC into DC and supplies it to the lamp
1
. Power supplied to the lamp
1
is controlled by the lamp lighting power source
21
.
The start-up circuit
21
b
generates high voltage so that dielectric breakdown takes place between electrodes of the lamp
1
at the start of discharge lamp lighting.
In turning on a short-arc discharge lamp such as an ultrahigh-pressure mercury discharge lamp, high voltage is instantaneously impressed between the electrodes at a frequency greater than 1 MHz so that the dielectric breakdown takes place and the discharge lamp is turned on. The start-up circuit is called an ignitor, or a starter.
The controlling unit
22
receives output of a controlling section
23
for controlling the exposure apparatus, and controls opening of the shutter plate
61
according to output from the controlling section
23
, the accumulated light amount measuring unit
12
and the shutter opening/closing detecting sensor
63
or controls to turn on and off the lamp
1
by controlling the lamp lighting power source
21
.
In the light emitting unit
10
, the lamp
1
is always tuned on.
In order to make the accumulated light amount emitted on the work piece having the light exposure surface uniform, the controller
22
controls opening of the shutter plate
61
during a period from the opening of the shutter (the start of emission) to the closing of the shutter (end of emission) by controlling the shutter mechanism
6
according to the output of the accumulated light amount measuring unit
12
so that accumulated light amount (light exposure amount) on the light exposure surface becomes a desired value.
The lamp
1
is always turned on because in general once the lamp
1
including mercury in inclusive gas is turned off, the lamp
1
cannot be re-lighted easily since the dielectric breakdown voltage is high while the temperature of the lamp is still high, therefore, the lamp
1
would not be tuned on unless the lamp is cooled off so that the dielectric breakdown voltage becomes sufficiently low.
“Relight” means that power is applied to the lamp
1
to turn on the lamp after the lamp is turned off but while the lamp does not sufficiently cool down.
In
FIGS. 9A and 9B
, an example of the shutter mechanism
6
for the light emitting apparatus is shown.
The shutter plate
61
has light transmission portions
64
and light blocking portions
65
. The shutter plates
61
are unidirectionally (in a direction shown as an arrow) rotated with respect to a rotation axis
66
by the shutter driving unit
62
such as a motor (not shown).
When the shutter plate
61
is in a position shown in
FIG. 9A
, light passes through the light transmission portion
64
. When the shutter plate
61
is in a position shown in
FIG. 9B
, the light is blocked by the light blocking portions
65
.
Description of the conventional accumulated light exposure amount control in the light emitting apparatus shown in
FIG. 8
will be given below.
At the beginning, the lamp
1
is turned on. When the lighting becomes stable and a work piece such as a wafer etc. is placed on the light exposure surface, the controlling unit
22
sends a shutter opening command to the shutter driving unit
62
. And then the shutter plate
61
is opened and light is emitted from the light outgoing window and then the wafer etc. placed on the light exposure surface is exposed.
The accumulated light exposure amount on the light exposure surface is controlled as described below.
As shown in
FIG. 8
, the illuminometer
11
is provided behind the second plane mirror
7
, and light transmitted through the light transmission portion such as a pinhole(s) etc. provided on part of the second plane mirror
7
is entered into the illuminometer
11
.
The illuminometer
11
is not placed on the light exposure surface since the shadow of the illuminometer
11
appears against the work piece (a mask etc.) during an actual exposure operation if the illuminometer
11
is placed on the light exposure surface and it is impossible to measure the illumination intensity.
In case that the illuminometer
11
receives the light transmitted through the light transmission portion, it is necessary to be set so that accumulated light amount exposed on the light exposure surface and accumulated light amount measured from the amount of light received by the illuminometer
11
are equivalent.
In particular, it is confirmed that they are in proportionality relation, and the constant of proportion is obtained.
An illumination intensity signal from the illuminometer
11
is input in the accumulated light amount measuring unit
12
and converted into accumulated light exposure amount.
The controlling unit
22
sends a shutter closing command to the shutter driving unit
62
so that the accumulated light amount is controlled to a predetermined value by predictive control described below and closes the shutter plate
61
. The operation constitutes one cycle of exposure process for the wafer etc.
As shown in
FIGS. 9A and 9B
, the shutter plate
61
is rotated. Therefore, it takes minimum amount of time to completely block light trace from a time when the shutter opening command is input to a time when the shutter plate
61
is
Komori Minoru
Sugimoto Hirotoshi
Philogene Haissa
Rader & Fishman & Grauer, PLLC
Ushio Denki Kabushiki Kaisha
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