U.S. patent application number 09/758271 was filed with the patent office on 2001-08-23 for pulse width modulated control apparatus.
Invention is credited to Motoori, Ryuzo.
Application Number | 20010015901 09/758271 |
Document ID | / |
Family ID | 18534001 |
Filed Date | 2001-08-23 |
United States Patent
Application |
20010015901 |
Kind Code |
A1 |
Motoori, Ryuzo |
August 23, 2001 |
Pulse width modulated control apparatus
Abstract
The present invention provides a PWM control apparatus which
makes it possible to obtain a high-precision, high-S/N-ratio,
low-cost, small-volume, light-weight motor driving apparatus. In
particular, to provide a motor driving apparatus using this PWM
control apparatus, a stage apparatus using this motor driving
apparatus, an exposure apparatus using this stage apparatus, a
device manufactured by means of the exposure apparatus, and a
device manufacturing method.
Inventors: |
Motoori, Ryuzo; (Kawasaki
city, JP) |
Correspondence
Address: |
MORGAN, LEWIS & BOCKIUS
1800 M STREET NW
WASHINGTON
DC
20036-5869
US
|
Family ID: |
18534001 |
Appl. No.: |
09/758271 |
Filed: |
January 12, 2001 |
Current U.S.
Class: |
363/41 |
Current CPC
Class: |
Y02B 70/10 20130101;
G03F 7/70725 20130101; H02M 3/1588 20130101; G03F 7/70358 20130101;
G03F 7/70758 20130101; Y02B 70/1466 20130101 |
Class at
Publication: |
363/41 |
International
Class: |
H02M 001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2000 |
JP |
2000-005323 |
Claims
What is claimed is:
1. A pulse-width-modulated (PMW) control apparatus comprising: a
triangular wave generating circuit which generates a triangular
wave; a comparator for comparing an input signal and the triangular
wave and outputting a PWM signal with a pulse width corresponding
to a voltage level of the input signal; switching elements which
are connected to a power supply for switching a voltage of the
power supply on and off and output a voltage based upon of the PWM
signal; and an adjustment circuit for adjusting a duty ratio of the
PWM signal according to fluctuations in the voltage of the power
supply.
2. The PWM control apparatus of claim 1, wherein the adjustment
circuit comprises a circuit for dividing the voltage of the input
signal by the voltage of the power supply.
3. The PWM control apparatus of claim 1, wherein the adjustment
circuit adjusts an amplitude of the triangular wave in accordance
with fluctuations in the voltage of the power supply.
4. The PWM control apparatus of claim 3, wherein the adjustment
circuit multiplies a triangular wave output from the triangular
wave generating circuit by the voltage of the power supply.
5. The PWM control apparatus of claim 3, wherein the adjustment
circuit adjusts a voltage of a triangular wave generating circuit
power supply that supplies power to the triangular wave generating
circuit in proportion to fluctuations of the voltage of the power
supply.
6. The PWM control apparatus of claim 3, wherein the triangular
wave generating circuit comprises: switching circuits for
alternately switching between two different signal levels at
specified frequencies; and, integrating circuits for integrating
outputs of the switching circuits and outputting a triangular wave,
wherein the adjustment circuit comprises an amplifier circuit that
outputs the two different signal levels, and wherein a signal level
difference of the two different signal levels varies in proportion
to fluctuations of the voltage of the power supply.
7. A PWM control apparatus comprising: a triangular wave generating
circuit for generating a triangular wave; a comparator for
comparing an input signal and the triangular wave and outputting a
PWM signal with a pulse width corresponding to a voltage level of
the input signal; switching elements connected to a power supply
for switching a voltage from the power supply on and off and
outputting a voltage based upon the PWM signal; and, an adjustment
circuit for adjusting the voltage level of the input signal input
to the comparator according to a variation of the voltage of the
power supply.
8. A PWM control apparatus comprising: a triangular wave generating
circuit for generating a triangular wave; a comparator for
comparing an input signal and the triangular wave and outputting a
PWM signal with a pulse width corresponding to a voltage level of
the input signal; switching elements connected to a power supply
for switching a voltage from the power supply on and off and
outputting a voltage based upon the PWM signal; and, an adjustment
circuit for adjusting an amplitude of the triangular wave according
to a variation of the voltage of the power supply.
9. A motor driving apparatus comprising: a motor driving circuit
having a current amplifier circuit, wherein the current amplifier
circuit comprises the PWM control apparatus claimed in any one of
claims 1 through 8.
10. A stage apparatus comprising: a stage that carries an object of
movement; a motor that drives the stage to move the object of
movement; and, the motor driving apparatus claimed in claim 9 which
drives the motor.
11. An exposure apparatus which forms a specified pattern on a
substrate by means of exposure, the exposure apparatus comprising
at least the stage apparatus of claim 10, which carries and moves
one of either a mask or the substrate.
12. A device manufactured by the exposure apparatus of claim
11.
13. A device manufacturing method comprising the exposure apparatus
of claim 11 and a process in which the exposure is performed by the
exposure apparatus.
14. A pulse-width-modulator (PWM) control method comprising: a
voltage from a power supply switched on and off and output on a
basis of a PWM signal having a pulse width that corresponds to a
voltage level of an input signal, wherein a duty ratio of the PWM
signal is adjusted based upon fluctuations in a voltage level of
the power supply.
Description
[0001] This application claims the benefit of Japanese Application
No. 2000-005323, filed in Japan on Jan. 14, 2000, which is hereby
incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a pulse-width-modulated
(PWM) control apparatus, a motor driving apparatus, a stage
apparatus, an exposure apparatus, a device that is manufactured by
means of this exposure apparatus, and a device manufacturing
method.
[0004] 2. Description of the Background Art
[0005] A semiconductor exposure apparatus is constructed from a
reticle stage that carries a reticle (or mask), a wafer stage that
carries a wafer, and a projection optical system that projects a
pattern formed on the reticle onto the wafer and exposes this
pattern. The respective stages are appropriately driven by motors
and motor driving apparatuses that drive these motors, so that the
pattern formed on the reticle is accurately projected and exposed
in a specified position on the wafer. Linear motors are used as the
motors that drive the respective stages, and high-efficiency
pulse-width-modulated (PWM) amplifier circuits are used as the
circuits that drive these linear motors. Since it is necessary that
the stage of the projection exposure apparatus be driven with a
high degree of precision, performance that offers high precision
and a high S/N ratio is required in this PWM amplifier circuit.
Accordingly, a switching regulator, etc., which allows sufficient
regulation is used in the power supply.
[0006] However, large-capacity switching regulators are expensive,
and have a large volume and weight, so that a large proportion of
the volume and weight of the semiconductor exposure apparatus is
occupied by such a switching regulator. On the other hand, in cases
where a simple transformer-less power supply is used,
high-frequency components of the power supply frequency remain in
the output of the amplifier circuit, so that there is a problem in
that performance that offers high precision and a high S/N ratio
cannot be guaranteed.
SUMMARY OF THE INVENTION
[0007] The present invention provides a PWM control apparatus which
makes it possible to realize a motor driving apparatus that has
high precision, a high S/N ratio, low cost, a small volume and a
low weight.
[0008] A motor driving apparatus of the present invention includes
a PWM control apparatus, a stage apparatus that uses this motor
driving apparatus, an exposure apparatus that uses this stage
apparatus, a device that is manufactured by means of this exposure
apparatus, and a device manufacturing method.
[0009] A PWM control apparatus of the present invention includes a
triangular wave generating circuit for generating a triangular
wave, a comparator for comparing an input signal and the triangular
wave and outputting a PWM signal with a pulse width corresponding
to a voltage level of the input signal, switching elements
connected to a power supply, and for switching a voltage from this
power supply on and off and output a voltage based upon the PWM
signal, and an adjustment circuit for adjusting a duty ratio of the
PWM signal according to fluctuations in the voltage of the power
supply.
[0010] The adjustment circuit of the present invention divides the
voltage of the input signal by the voltage of the power supply.
[0011] The adjustment circuit includes a circuit that adjusts the
amplitude of the triangular wave according to fluctuations in the
voltage of the power supply.
[0012] The adjustment circuit multiplies a triangular wave output
from the triangular wave generating circuit by the voltage of the
power supply.
[0013] The adjustment circuit adjusts a voltage level of a
triangular wave generating circuit power supply that supplies power
to the triangular wave generating circuit in proportion to
fluctuations of the voltage of the power supply.
[0014] The triangular wave generating circuit of the present
invention includes switching circuits that alternately switch
between two different signal levels at specified frequencies, and
integrating circuits that integrate outputs of the switching
circuits and output a triangular wave, and the adjustment circuit
includes an amplifier circuit that outputs the two different signal
levels, where a signal level difference of the two signal levels
varies in proportion to fluctuations of the voltage of the power
supply.
[0015] A PWM control apparatus of the present invention includes a
triangular wave generating circuit for generating a triangular
wave, a comparator for comparing an input signal and the triangular
wave and outputting a PWM signal with a pulse width corresponding
to a voltage level of the input signal, switching elements
connected to a power supply for switching a voltage from the power
supply on and off and outputting a voltage based upon the PWM
signal, and an adjustment circuit for adjusting the voltage level
of the input signal that is input into the comparator according to
a variation of the voltage of the power supply.
[0016] A PWM control apparatus of the present invention includes a
triangular wave generating circuit for generating a triangular
wave, a comparator for comparing an input signal and the triangular
wave and outputting a PWM signal with a pulse width corresponding
to a voltage level of the input signal, switching elements
connected to a power supply for switching a voltage from the power
supply on and off and outputting a voltage based upon the PWM
signal, and an adjustment circuit for adjusting an amplitude of the
triangular wave according to a variation of the voltage of the
power supply.
[0017] A motor driving apparatus of the present invention comprises
a current amplifier circuit which includes a PWM control apparatus
of the present invention.
[0018] A stage apparatus of the present invention comprises a stage
that carries an object of movement, a motor that drives the stage
to move the object of movement, and a motor driving apparatus of
the present invention which drives the motor.
[0019] An exposure apparatus of the present invention forms a
specified pattern on a substrate by means of exposure, and is
equipped with at least a stage apparatus of the present invention
which carries and moves either a mask or a substrate.
[0020] A device of the present invention which is manufactured by
means of an exposure apparatus of the present invention.
[0021] A device of the present invention which is manufactured by
using an exposure apparatus of the present invention and comprises
a process in which the exposure is performed by means of the
exposure apparatus of the present invention.
[0022] A PWM control method of the present invention in which the
voltage from a power supply is switched on and off and output on
the basis of a PWM signal having a pulse width that corresponds to
a voltage level of an input signal, and is devised so that a duty
ratio (degree of modulation) of the PWM signal is adjusted based
upon fluctuations in a voltage level of the power supply.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 shows a schematic construction of a projection
exposure apparatus of the present invention.
[0024] FIG. 2 shows a circuit construction of a motor driving
apparatus used to drive a linear motors in a first embodiment of
the present invention.
[0025] FIG. 3 illustrates conditions of a power supply including a
ripple.
[0026] FIG. 4 shows a circuit construction of a motor driving
apparatus used to drive linear motors in a second embodiment of the
present invention.
[0027] FIG. 5 shows a circuit construction of a motor driving
apparatus used to drive linear motors in a third embodiment of the
present invention.
[0028] FIG. 6 shows a circuit construction of a motor driving
apparatus used to drive linear motors in a fourth embodiment of the
present invention.
[0029] FIG. 7 shows a flow chart illustrating a semiconductor
manufacturing process of the present invention.
[0030] FIG. 8 shows a detailed flow chart of step S304 in FIG.
7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0031] Reference will now be made in detail to the preferred
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings.
[0032] First, a projection exposure apparatus in which stages are
driven by a motor driving apparatus using a PWM control apparatus
(PWM circuit) of the present invention will be described.
[0033] FIG. 1 shows a schematic construction of the projection
exposure apparatus of the present invention. This projection
exposure apparatus is a stepper type (step-and-repeat type)
projection exposure apparatus which exposes a reduced image of the
pattern of a reticle on respective shot areas of a wafer.
Furthermore, in this first working configuration, the term
"reticle" is used; however, in the present specification, both
"reticle" and "mask" are treated as having the same meaning as
parts on which a pattern that is to be projected onto the wafer is
formed. In FIG. 1, exposing light IL from an illumination system 1
is reflected by a dichroic mirror 2, so that this light illuminates
the pattern area on the reticle R. The Z axis is taken parallel to
the optical axis of the exposing light IL that has been reflected
by the dichroic mirror 2. The X axis is taken in the direction
parallel to the plane of the page in FIG. 1 within the
two-dimensional plane that is perpendicular to the Z axis, and the
Y axis is taken in the direction that is perpendicular to the plane
of the page in FIG. 1.
[0034] The reticle R is carried on a reticle base 4 via a
reticle-side stage 3Y and a reticle-side stage 3X. The reticle-side
stage 3X is driven in the X direction with respect to the reticle
base 4 via a linear motor (hereafter referred to as the "X-axis
linear motor 5") comprising a fixed element 5A and a movable
element 5B, and the reticle-side stage 3Y is driven in the Y
direction with respect to the reticle-side stage 3X by a linear
motor not shown in the figures.
[0035] Furthermore, an X-axis movable mirror 6X and a Y-axis
movable mirror (not shown in the figures) are fastened to the
surface of the reticle-side stage 3Y, and the X-coordinate XR of
the reticle-side stage 3X is measured by the movable mirror 6X and
an X-axis reticle-side laser interferometer (hereafter referred to
as a "reticle interferometer") 7X installed on the outside. The
Y-coordinate YR of the reticle-side stage 3Y is measured by a
Y-axis movable mirror (not shown in the figures) and a Y-axis
reticle interferometer 7Y. The measured X-coordinate XR and
Y-coordinate YR are supplied via connectors 17 and 18 to a central
control system 8 which performs comprehensive control of the
operation of the apparatus as a whole. The stage system comprising
the reticle-side stage 3Y, reticle-side stage 3X, reticle base 4,
X-axis linear motor 5 and Y-axis linear motor is collectively
referred to as the "reticle stage apparatus 3."
[0036] Through the intermediary of the exposing light IL, an image
of the pattern on the reticle R is reduced via a projection optical
system PL, which has a projection magnification of .beta. (for
example, .beta. is 1/5), and is projected and exposed on the
respective shot areas of the wafer W. The wafer W is carried on a
wafer base 11 via a wafer-side stage 10Y and wafer-side stage 10X.
The wafer-side stage 10X is driven in the X direction with respect
to the wafer base 11 via a linear motor (hereafter referred to as
the "linear motor 12") consisting of a fixed element 12A and a
movable element 12B, and the wafer-side stage 10Y is driven in the
Y direction with respect to the wafer-side stage 10X by a linear
motor not shown in the figures.
[0037] Furthermore, an X-axis movable mirror 13X and a Y-axis
movable mirror (not shown in the figures) are fastened to the
surface of the wafer-side stage 10Y, and the X-coordinate X, of the
wafer-side stage 10X is measured by the movable mirror 13X and an
X-axis wafer-side laser interferometer (hereafter referred to as a
"wafer interferometer") 14X installed on the outside. The
Y-coordinate YW of the wafer-side stage 10Y is measured by a Y-axis
movable mirror (not shown in the figures) and a Y-axis wafer
interferometer 14Y. The measured X-coordinate X, and Y-coordinate
YW are supplied via connectors 19 and 20 to the central control
system 8. The stage system comprising the wafer-side stage 10Y,
wafer-side stage 10X, wafer base 11, X-axis linear motor 12, Y-axis
linear motor and a Z leveling stage (not shown in the figures)
which controls the position of the wafer W in the Z direction and
the angle of inclination of the wafer W will be collectively
referred to as the "wafer stage apparatus 10."
[0038] In the first embodiment of the present invention,
three-phase linear motors are used as the linear motors. The linear
motor 12 will be described as an example. The linear motor 12 is
constructed from a fixed element 12A and a movable element 12B. The
fixed element 12A comprises a three-phase armature coil (not shown
in the figures), and the movable element 12B consists of four
permanent magnets (not shown in the figures) that are fastened to
the side surface of the wafer-side stage 10X side by side in the X
direction with the polarities of these magnets alternately
inverted. Specifically, the linear motor 12 is a moving magnet type
linear synchronous motor. Furthermore, it would also be possible to
use a moving coil type linear motor in which the armature coil is
accommodated on the side of the movable element.
[0039] The central control system 8 positions the reticle R by
controlling the operation of the reticle-side X-axis linear motor 5
and Y-axis linear motor via the reticle stage driving system 15,
and positions the wafer W by controlling the operation of the
wafer-side X-axis linear motor 12 and Y-axis linear motor via the
wafer stage driving system 16. As a result of this control, the
pattern on the reticle R is reduced and exposed on the respective
shot areas of the wafer W.
[0040] The reticle stage driving system 15 and wafer stage driving
system 16 mount motor driving apparatuses that respectively drive
the linear motors 5 and 12. The motor driving apparatuses will be
described in detail below.
[0041] FIG. 2 shows a circuit construction of a motor driving
apparatus that drives one of the linear motors of the present
invention. Both of the motor driving apparatuses that drive the
respective linear motors 5 and 12 are the same in principle;
accordingly, one motor driving apparatus that drives one linear
motor 5 will be described here as a representative example. The
motor driving apparatus shown in FIG. 2 is a current-controlling
apparatus (current amplifier circuit) which controls the current
that flows to the linear motor 5 in accordance with the voltage
level of an input signal (I). In accordance with a specified
program, the central control system 8 detects the X-coordinate of
the reticle stage 3X by means of a signal from the reticle
interferometer 7X, and calculates and outputs a driving signal
(input signal I) so that the linear motor 5 is appropriately driven
in the X direction.
[0042] The motor driving apparatus shown in FIG. 2 uses a PWM
(pulse width modulation) system to control the output current in
accordance with the voltage level of the input signal 1. In FIG. 2,
the triangular wave generating circuit 101 comprises resistors R1,
R2 and R3, a capacitor C1 and operational amplifiers U1 and U2;
this circuit outputs a triangular wave comprising a specified
frequency and amplitude. The input signal I is a signal that has
the sign .+-. (plus or minus), and the triangular wave is also a
periodic signal that oscillates at the same amplitude plus or
minus. As is shown in the figures, the difference detector 102
comprises resistors R4 and R5, a capacitor C2 and an operational
amplifier U3. This detector compares the input signal I with the
signal from a current sensor 109 (described later), and amplifies
and outputs the difference between the two signals. The comparator
103 comprises a comparator U5; this comparator 103 compares the
triangular wave from the triangular wave generating circuit 101
with the input signal I input via a dividing circuit 104 (described
later), and outputs a PWM-signal (pulse-width-modulated signal).
Specifically, a signal formed by pulse-width-modulating the input
signal I is output. This pulse width modulation system comprises a
well known construction.
[0043] The PWM signal that constitutes the output of the comparator
103 is level-shifted by a photo-coupler 105, and is input into a
PWM driver 106. In this case, a signal inverted by an inverter 107
is also input into the PWM driver 106. The PWM driver 106 comprises
a bridge circuit, and drives the switching of switching FETs Q1 and
Q2 on the basis of the PWM signal. The low-pass filter 108
comprises a coil L1 and a capacitor C3; this low-pass filter 108
removes the switching components from the output signals of the
switching FETs Q1 and Q2, and produces the desired output signal
OUT.
[0044] The current component of the output signal OUT from the
low-pass filter 108 is detected by the current sensor 109, and is
fed back to the above-mentioned difference detector 102. The
current sensor 109 comprises a Hall element, and produces a voltage
in accordance with the current that flows therethrough. Thus, since
the output current is detected and fed back, the motor driving
apparatus shown in FIG. 2 acts as an output current control device
(current amplifier). Furthermore, the current sensor 109 could also
comprise a resistor and an amplifier circuit instead of a Hall
element.
[0045] The power for the switching FETs Q1 and Q2 is supplied by a
power supply circuit 110. The power supply circuit 110 comprises
diodes D1 through D6, and supplies only power obtained by
rectifying a three-phase, 200 V alternating-current power supply.
Since the power supply circuit 110 supplies only power obtained by
rectifying a three-phase, 200 V alternating-current power supply,
this results in a power supply 112 which includes a ripple such as
that shown in FIG. 3. This ripple is a 300 Hz ripple if the
three-phase, 200 V power supply 112 has a frequency of 50 Hz.
[0046] If the power supply 112 containing this ripple is used "as
is" as the power supply for the switching FETs Q1 and Q2, the
output signals of the switching FETs Q1 and Q2 will be signals that
have a noise component that is affected by this ripple.
Accordingly, in the motor driving apparatus of the present working
configuration, a dividing circuit 104 is used in order to eliminate
the effect of the ripple component of the power supply 112.
[0047] The differential amplifier 111 comprises resistors R9
through R12 and an operational amplifier U6; this amplifier detects
the voltage of the power supply 112, amplifies this voltage by a
specified coefficient, and inputs the amplified voltage into the
dividing circuit 104. The dividing circuit 104 comprises a divider
U4, and resistors R6 and R7 that determine the coefficient of
division; this dividing circuit 104 divides the signal from the
difference detection circuit 102 by the signal from the
differential amplifier 111, and inputs the result into the
comparator 103. Specifically, the input signal I following the
feedback of the output current is input into the comparator 103
after being divided by the voltage level of the power supply 112.
In concrete terms, the input signal I is corrected to a smaller
value in cases where the power supply 112 fluctuates to a large
value, and the input signal I is corrected to a larger value in
cases where the power supply 112 fluctuates to a small value.
[0048] The circuit constants of the dividing circuit 104 and
differential amplifier 111 are determined so that in cases where
the input signal I has a fixed value, the output signal OUT will
show a fixed value that is unaffected by any ripple even if power
from a power supply 112 containing a ripple component is supplied
to the switching FETs Q1 and Q2.
[0049] Furthermore, in the circuit shown in FIG. 2, the input
signal I is a voltage signal which has a sign of .+-. (plus or
minus), and in cases where the voltage is .+-.zero, the duty ratio
of the PWM signal is adjusted to a value of 50% so that the output
current OUT will be zero. When the input signal I varies in the
positive direction, the duty ratio of the PWM signal varies to a
value that is smaller than 50%, so that the output current OUT
flows in the positive direction in accordance with the magnitude of
the input signal I. On the other hand, when the input signal I
varies in the negative direction, the duty ratio of the PWM signal
varies to a value that is greater than 50%, so that the output
current OUT flows in the negative direction in accordance with the
magnitude of the input signal I. In the above description, a simple
reference to the "magnitude of the input signal I" indicates the
magnitude of the absolute value of the input signal I.
[0050] Thus, in a circuit using the PWM system (hereafter referred
to simply as a "PWM circuit") of the present invention, the output
signal OUT (i.e., the output current in the first working
configuration) is controlled by varying the duty ratio (degree of
modulation) of the PWM signal in accordance with the magnitude of
the input signal I. In the PWM circuit of the first embodiment of
the present invention, the duty ratio of this PWM signal is
adjusted in accordance with fluctuations in the power supply 112.
More concretely, in cases where the power supply 112 fluctuates to
a large value, the output current OUT becomes larger than the
target current; accordingly, the duty ratio of the PWM signal is
adjusted so that it approaches 50% in order to reduce the output
current OUT. In the first embodiment of the present invention, in
order to make this adjustment, a dividing circuit 104 which divides
the input signal I by the magnitude of the power supply 112 is
inserted. Specifically, in cases where the power supply 112 shows a
large fluctuation, the input signal I is controlled to a small
value by the dividing circuit 104; as a result, the duty ratio of
the PWM signal approaches 50%, so that the output current OUT is
adjusted to a smaller value.
[0051] Thus, since the output current is adjusted in accordance
with fluctuations in the power supply voltage level 112 of the
power supply circuit 110, there is no need to install a power
supply with a highly precise regulation in the power supply circuit
as in conventional devices. The circuit shown in FIG. 2 merely uses
a power supply circuit 110 that comprises diodes D1 through D6 that
rectify a 3-phase, 200 V power source. As a result, an extreme
reduction in the cost of the power supply, reduction in volume and
reduction in weight can be realized; furthermore, the
high-precision, high-S/N-ratio motor driving that is required in an
exposure apparatus, etc., can also be realized. As a result, a
reduction in cost, reduction in volume and reduction in weight can
be realized while maintaining high-precision, high-S/N-ratio stage
driving in the stage apparatus and in an exposure apparatus, etc.,
using this stage apparatus.
[0052] Furthermore, in the above-mentioned embodiment, the
relationship between the direction of the variation of the duty
ratio in the PWM signal and the direction of the output current OUT
may in some cases be reversed depending on the circuit
construction.
[0053] In a second embodiment of the present invention, another
working configuration of the motor driving apparatus shown in FIG.
2 in the first working configuration will be described. The motor
driving apparatus of the second working configuration can also be
used in the projection exposure apparatus shown in FIG. 1 in the
same manner as in the first embodiment. Accordingly, a description
of the projection exposure apparatus will be omitted, and the
following description will refer to FIG. 1 in regard to the
projection exposure apparatus.
[0054] FIG. 4 is a diagram which shows the circuit construction of
a motor driving apparatus that drives one linear motor. The
difference between this motor driving apparatus and the motor
driving apparatus shown in FIG. 2 in the first embodiment is that
in this motor driving apparatus, the dividing circuit 104 installed
on the output side of the difference detection circuit 102 is
omitted, and a multiplying circuit 201 is installed on the output
side of the triangular wave generating circuit 101 instead. The
remaining parts are the same as in the motor driving apparatus
shown in FIG. 2; accordingly, the same symbols are assigned to
constituent elements that are common to both motor driving
apparatuses, and a description of such elements is omitted.
[0055] The multiplying circuit 201 comprises a multiplier U21 and
resistors R21 and R22 that determine the coefficient of
multiplication. The triangular wave from the triangular wave
generating circuit 101 is multiplied by the signal from the
differential amplifier 111, and the result is input into the
comparator 103. More concretely, in cases where the power supply
112 fluctuates to a large value, a correction is made so that the
amplitude of the triangular wave increases, and in cases where the
power supply 112 fluctuates to a small value, a correction is made
so that the amplitude of the triangular wave decreases.
[0056] The circuit constants of the multiplying circuit 201 and
differential amplifier 111 are to determined so that in cases where
the input signal I has a fixed value, the output signal OUT will
show a fixed value that is unaffected by any ripple even if power
from a power supply 112 containing a ripple component is supplied
to the switching FETs Q1 and Q2.
[0057] As in the first embodiment, the input signal I is a voltage
signal which has a sign of .+-. (plus or minus), and in cases where
the voltage is .+-.zero, the duty ratio of the PWM signal is
adjusted to a value of 50% so that the output current OUT will be
zero. Since the relationship between the variation in the input
signal I and the variation in the duty ratio of the PWM signal is
the same as was described in the first working configuration, a
description of this relationship will be omitted here.
[0058] The PWM circuit in the second embodiment is also a circuit
that adjusts the duty ratio of the PWM signal in accordance with
fluctuations in the power supply 112. More concretely, in cases
where the power supply 112 fluctuates to a large value, the output
current OUT becomes larger than the target current; accordingly,
the duty ratio of the PWM signal is adjusted so that it approaches
50% in order to reduce the output current OUT. In the second
embodiment a multiplying circuit 201 which multiplies the
triangular wave signal that is the output of the triangular wave
generating circuit 101 by the magnitude of the power supply 112 is
inserted in order to make this adjustment.
[0059] This utilizes the fact that when the amplitude of the
triangular wave increases in cases where the signal levels that are
input into the comparator 103 are the same signal levels in the
circuit construction shown in FIG. 4, the duty ratio of the PWM
signal approaches 50%. Accordingly, in cases where the power supply
112 fluctuates to a large value, the triangular wave is controlled
by the multiplying circuit 201 so that this triangular wave has a
large amplitude; as a result, the duty ratio of the PWM signal
approaches 50% so that the output current OUT is adjusted to a
smaller value.
[0060] Thus, in the second embodiment as well, the output current
is adjusted in accordance with fluctuations in the power supply
voltage level 112 of the power supply circuit 110; accordingly,
there is no need to install a power supply with a highly precise
regulation in the power supply circuit as in conventional devices.
As a result, the same effect as that of the first embodiment can be
obtained.
[0061] In a third embodiment of the present invention, another
embodiment of the motor driving apparatus shown in FIG. 2 in the
first embodiment will be described. The motor driving apparatus of
the third embodiment can also be used in the projection exposure
apparatus shown in FIG. 1 in the same manner as in the first
embodiment. Accordingly, a description of the projection exposure
apparatus will be omitted, and the following description will refer
to FIG. 1 in regard to the projection exposure apparatus.
[0062] FIG. 5 is a diagram which illustrates the circuit
construction of a motor driving apparatus that drives one linear
motor. The difference between this motor driving apparatus and the
motor driving apparatus shown in FIG. 2 in the first embodiment is
that in this motor driving apparatus, the dividing circuit 104
installed on the output side of the difference detection circuit
102 is omitted, and a triangular wave power supply circuit 301 that
supplies power to the triangular wave generating circuit 101 is
installed. The differential amplifier 111 is also removed. The
remaining parts are the same as in the motor driving apparatus
shown in FIG. 2; accordingly, the same symbols are assigned to
constituent elements that are common to both motor driving
apparatuses, and a description of such elements is omitted.
[0063] The triangular wave power supply circuit 301 comprises a
differential amplifier consisting of resistors R31, R32, R33 and
R34 and an operational amplifier U35, and an inverted amplifier
consisting of resistors R35 and R36 and an operational amplifier
U32. A voltage signal "V-" corresponding to the voltage of the
power supply 112 is generated by this differential amplifier, and a
voltage signal "V+" with the sign inverted is generated by the
inverted amplifier. The voltage "V+" and voltage "V-" generated by
the triangular wave power supply circuit 301 are supplied as
.+-.power supplies of the operational amplifiers U1 and U2 of the
triangular wave generating circuit 101.
[0064] The amplitude of the triangular wave generated by the
triangular wave generating circuit 101 varies according to the
power supply levels supplied to the operational amplifiers U1 and
U2. In the third embodiment, this property is utilized to adjust
the amplitude of the triangular wave in the same manner as in the
second embodiment. More concretely, in cases where the power supply
112 fluctuates to a large value, the potential difference between
the voltage "V+" and voltage "V-" generated by the triangular wave
power supply circuit 301 is controlled to a large value. As a
result, the amplitude of the triangular wave generated by the
triangular wave generating circuit 101 is also corrected to a
larger value. Similarly, in cases where the power supply 112
fluctuates to a small value, the amplitude of the triangular wave
is corrected to a smaller value.
[0065] The circuit constants of the triangular wave power supply
circuit 301 are determined so that the voltages "V+" and "V-" are
at a voltage level that is suitable as a power supply for the
triangular wave generating circuit 101, and so that in cases where
the input signal I has a fixed value, the output signal OUT will
show a fixed value that is unaffected by any ripple even if power
from a power supply 112 containing a ripple component is supplied
to the switching FETs Q1 and Q2.
[0066] The relationship between the amplitude of the triangular
wave and the duty ratio of the PWM signal is the same as was
described in the second embodiment; accordingly, a description of
this relationship is omitted here.
[0067] Thus, in this third embodiment as well, the output current
is adjusted in accordance with fluctuations in the power supply
voltage level 112 of the power supply circuit 110; accordingly,
there is no need to install a power supply with a highly precise
regulation in the power supply circuit as in conventional devices.
As a result, the same effect as that of the first embodiment can be
obtained.
[0068] In a fourth embodiment of the present invention, another
embodiment of the motor driving apparatus shown in FIG. 2 in the
first embodiment will be described. The motor driving apparatus of
the fourth embodiment can also be used in the projection exposure
apparatus shown in FIG. 1 in the same manner as in the first
embodiment. Accordingly, a description of the projection exposure
apparatus will be omitted, and the following description will refer
to FIG. 1 in regard to the projection exposure apparatus.
[0069] FIG. 6 is a diagram which illustrates the circuit
construction of a motor driving apparatus that drives one linear
motor. The difference between this motor driving apparatus and the
motor driving apparatus shown in FIG. 2 in the first embodiment is
that in this motor driving apparatus, the dividing circuit 104
installed on the output side of the difference detection circuit
102 is omitted, and another triangular wave generating circuit 401
is installed instead of the triangular wave generating circuit 101.
Furthermore, the differential amplifier 111 is also removed, and a
triangular wave level signal generating circuit 404 which generates
.+-.triangular wave level signals S1 and S2 that vary according to
fluctuations in the power supply 112 is installed. The remaining
parts are the same as in the motor driving apparatus shown in FIG.
2; accordingly, the same symbols are assigned to constituent
elements that are common to both motor driving apparatuses, and a
description of such elements is omitted.
[0070] The triangular wave generating circuit 401 comprises an
oscillator (OSC) 403 which determines the period of the triangular
wave, a switching element 402 which receives the signal from the
OSC 403 and alternately switches between a "+" triangular wave
level signal S1 and a "-" triangular wave level signal S2, and an
integrating circuit comprising a resistor R41, a capacitor C41 and
an operational amplifier U41, which integrate the output signal
from the switching element 402. A triangular wave is output from
this integrating circuit and input into the comparator 103. The
amplitude of the triangular wave is determined by the voltage
levels of the .+-.triangular wave level signals S1 and S2, the
period of the OSC 403, and the values of the resistor R41 and
capacitor C41, etc. In the third embodiment, the amplitude of the
triangular wave is adjusted by varying the voltage levels of the
triangular wave level signals S1 and S2 (among the above-mentioned
values). In regard to the adjustment of the amplitude of the
triangular wave, this embodiment is the same as the second and
third embodiments.
[0071] The triangular wave level signals S1 and S2 are generated by
the triangular wave level signal generating circuit 404. The
triangular wave level signal generating circuit 404 comprises a
differential amplifier consisting of resistors R42, R43, R44 and
R45 and an operational amplifier U42, and an inverted amplifier
consisting of resistors R46 and R47 and an operational amplifier
U43. A "-" triangular wave level signal S1 corresponding to the
voltage of the power supply 112 is generated by this differential
amplifier, and a "+" triangular wave level signal S2 in which the
sign of the above-mentioned signal S1 is inverted is generated by
the inverted amplifier. The .+-. triangular wave level signals S1
and S2 generated as triangular wave level signals are input into
the switching element 402 of the triangular wave generating circuit
401.
[0072] A triangular wave with an amplitude corresponding to
fluctuations in the power supply 112 is generated by the triangular
wave level signal generating circuit 404 and triangular wave
generating circuit 401 constructed as described above. More
concretely, in cases where the power supply 112 fluctuates to a
large value, the potential difference between the .+-.triangular
wave level signals S1 and S2 generated by the triangular wave level
signal generating circuit 404 is controlled to a large value. As a
result, the amplitude of the triangular wave generated by the
triangular wave generating circuit 401 is also corrected to a
larger value. Similarly, in cases where the power supply 112
fluctuates to a small value, the amplitude of the triangular wave
is corrected to a smaller value.
[0073] The respective circuit constants of the triangular wave
level signal generating circuit 404 and triangular wave generating
circuit 401 are determined so that the amplitude of the triangular
wave is controlled to a voltage level that is appropriate for the
PWM circuit shown in FIG. 6, and so that in cases where the input
signal I has a fixed value, the output signal OUT will show a fixed
value that is unaffected by any ripple even if power from a power
supply 112 containing a ripple component is supplied to the
switching FETs Q1 and Q2.
[0074] The relationship between the amplitude of the triangular
wave and the duty ratio of the PWM signal is the same as was
described in the second embodiment; accordingly, a description of
this relationship is omitted here.
[0075] Thus, in this fourth embodiment as well, the output current
is adjusted in accordance with fluctuations in the power supply
voltage level 112 of the power supply circuit 110; accordingly,
there is no need to install a power supply with a highly precise
regulation in the power supply circuit as in conventional devices.
As a result, the same effect as that of the first embodiment can be
obtained.
[0076] Furthermore, synchronous linear motors that are driven by
applying a three-phase current of mutually different phases are
known as linear motors used in the projection exposure apparatus
shown in FIG. 1. In the case of such linear motors, current
amplification by means of a PWM system is applied to the currents
of the respective phases. In this case, the power supply circuit
110, the triangular wave level signal generating circuit 404 and
the OSC 403 and switching element 402 of the triangular wave
generating circuit 401 shown in FIG. 6 may be constructed so that
they are shared by the respective phases. Furthermore, within the
triangular wave generating circuit 401, it is sufficient if an
integrating circuit comprising the resistor R41, capacitor C41 and
operational amplifier U41 is installed for each of the circuits
used for the respective phases.
[0077] Furthermore, even in the case of apparatuses which have a
plurality of linear motors and are equipped with a plurality of
motor driving apparatuses in order to drive these linear motors,
the power supply circuit 110, the triangular wave level signal
generating circuit 404 and the OSC 403 and switching element 402 of
the triangular wave generating circuit 401 may be constructed so
that these parts are shared by the respective linear motor driving
apparatuses. By doing this, it is possible to obtain
synchronization of the triangular wave among the respective
currents that are applied to the motors, so that the generation of
noise such as a beat signal, etc., can be prevented.
[0078] To say that the PWM amplifier circuit of a motor driving
apparatus is affected by the power supply voltage refers to the
fact that the PWM amplifier circuit absorbs variations in the
output current caused by the power supply voltage by varying the
loop gain. As a result, the gain and phase frequency
characteristics vary. Accordingly, in the first through fourth
embodiments, the voltage of the input signal or the amplitude of
the triangular wave (for example) are operationally treated on the
basis of the variation in the power supply voltage, so that the
loop gain is not affected by fluctuations in the power supply
voltage. As a result, a high-precision motor driving apparatus can
be realized even in cases where the power supply is more or less
unstable or contains a ripple.
[0079] In the above-mentioned first through fourth embodiments,
examples were described in which the present invention was applied
to systems using a rectified 3-phase, 200 V power supply as a power
supply; however, the present invention is not necessarily limited
to such a power supply. The present invention can be applied in
cases using any type of power supply in which sufficient regulation
cannot be obtained.
[0080] Furthermore, also in regard to the circuit that performs an
adjustment according to fluctuations in the power supply, the
present invention is not necessarily limited to the above-mentioned
embodiments. Any circuit that is capable of adjusting the duty
ratio of the PWM signal in accordance with fluctuations in the
power supply that supplies power to the switching elements of the
PWM circuit may be used. In particular, several concrete examples
of circuits that adjust the amplitude of the triangular wave were
described; however, it would of course be possible to use any other
circuit that adjusts the amplitude of the triangular wave.
[0081] In the above embodiments, a PWM current amplifier circuit
was indicated; however, the present invention can also be applied
to a PWM voltage amplifier circuit.
[0082] In the above embodiments, a motor driving apparatus, a stage
apparatus utilizing this motor driving apparatus, and an projection
exposure apparatus utilizing this stage apparatus, were indicated
as examples of application of the PWM circuit of the present
invention. However, the present invention is not necessarily
limited to such examples of application. The present invention can
be applied to any circuit or apparatus that uses a PWM circuit. In
such cases, the effect of the present invention is exhibited when
the regulation of the power supply supplying power to the switching
elements of the PWM circuit is insufficient.
[0083] In regard to the exposure apparatus of the present
embodiment of the invention, the present invention can also be
applied to a scanning type exposure apparatus in which the mask
pattern is exposed by synchronously moving the mask and substrate.
For example, such a scanning type exposure apparatus is disclosed
in U.S. Pat. No. 5,473,410; the present invention can also be
applied to such an exposure apparatus.
[0084] In regard to the exposure apparatus of the present
embodiment, the present invention can also be applied to a
proximity exposure apparatus in which the mask pattern is exposed
by causing the mask to adhere tightly to the substrate, without
using a projection optical system.
[0085] The application of the exposure apparatus is not limited to
an exposure apparatus used in semiconductor manufacture. For
example, the present invention is also widely suitable for use in
liquid crystal exposure apparatuses that expose liquid crystal
display element patterns on square glass plates, and exposure
apparatuses that are used to manufacture thin-film magnetic
heads.
[0086] Not only the g line (436 nm), i line (365 nm), KrF excimer
lasers (248 nm), ArF excimer lasers (193 nm) and F.sub.2 lasers
(157 nm), but also charged-particle beams such as X-rays or
electron beams, etc., can be used as the light source of the
exposure apparatus of the present working configuration. For
example, in cases where an electron beam is used, thermo-electron
emitting type lanthanum hexaborite (LaB.sub.6) or tantalum (Ta) can
be used as the electron gun. Furthermore, in cases where an
electron beam is used, a construction using a mask may be employed,
or a construction in which the pattern is formed on the substrate
by direct drawing using an electron beam (without using any mask)
may be employed.
[0087] In regard to the magnification of the projection optical
system, the system used is not limited to a reducing system, but
may also be either an equal-magnification system or an enlarging
system.
[0088] In cases where far ultraviolet light such as light from an
excimer laser, etc., is used in the projection optical system,
materials that transmit far ultraviolet light such as quartz or
fluorite, etc., may be used as glass materials. Furthermore, in
cases where an F.sub.2 laser or X-rays are used, the optical system
may be a reflective-refractive system or refractive system (a
reflective type reticle may also be used), and in cases where an
electron beam is used, an electron optical system consisting of
electron lenses and deflectors may be used as the optical system.
Moreover, it goes without saying that the light paths through which
the electron beam passes are placed in a vacuum state.
[0089] In the case of an exposure apparatus using vacuum
ultraviolet light (VUV light) with a wavelength of approximately
200 nm or less, the use of a reflective-refractive type optical
system as a projection optical system is also conceivable. For
example, as a reflective-refractive type optical system, a
reflective-refractive type optical system which has beam splitters
and concave mirrors as reflective optical elements (as disclosed in
Japanese Patent Application Kokai No. HEI 8-171054 and the
corresponding U.S. Pat. No. 5,668,672, as well as in Japanese
Patent Application Kokai No. HEI 10-20195 and the corresponding
U.S. Pat. No. 5,835,275) may be used. Furthermore, a
reflective-refractive type optical system which has concave
mirrors, etc., as reflective optical elements (without using beam
splitters), as disclosed in Japanese Patent Application Kokai No.
HEI 8-334695 and the corresponding U.S. Pat. No. 5,689,377, and in
Japanese Patent Application Kokai No. HEI 10-3039 and the
corresponding U.S. Pat. No. 5,873,605, etc., may also be used. The
present invention can also be applied to exposure apparatuses
equipped with such projection optical systems.
[0090] In addition, a reflective-refractive type optical system in
which a plurality of refractive optical elements and two mirrors (a
main mirror consisting of a concave mirror, and an auxiliary mirror
consisting of a backed mirror which has an incident surface formed
by a reflective element or parallel flat plate and which has a
reflective surface formed on the opposite side) are disposed on the
same optical axis, and an intermediate image of the reticle pattern
formed by the plurality of refractive optical elements is
re-focused on the wafer by the main mirror and auxiliary mirror, as
disclosed in U.S. Pat. No. 5,031,976, U.S. Pat. No. 5,488,229 and
U.S. Pat. No. 5,717,518, may also be used. In this
reflective-refractive type optical system, the main mirror and
auxiliary mirror are disposed after the plurality of refractive
optical elements, and the illuminating light reaches the surface of
the wafer via a portion of the main mirror.
[0091] Furthermore, a reducing system which has a circular image
field, in which the object plane side and image plane side are both
telecentric, and in which the projection magnification is
1/4.times. or 1/5.times., may also be used as a
reflective-refractive type projection optical system. In the case
of a scanning type exposure apparatus equipped with this
reflective-refractive type projection optical system, this
apparatus may be of the type in which the illumination area of the
illuminating light is substantially centered on the optical axis of
the projection optical system within the visual field of the
projection optical system, and is restricted to a rectangular slit
form that extends in a direction substantially perpendicular to the
scanning direction of the reticle or wafer. In the case of such a
scanning type exposure apparatus, for example, a fine pattern of
approximately 100 nmL/S can be transferred onto the wafer with high
precision even if F.sub.2 laser light with a wavelength of 157 nm
is used as the illuminating light for exposure. The present
invention can also be applied to an exposure apparatus equipped
with such a projection optical system.
[0092] The linear motors used for the wafer stage or reticle stage
may be either air-floating type motors using air bearings, or
magnetic-floating type motors using Lorentz force or reactance
force. Moreover, the stages may be of a type that moves along
guides, or of a guideless type that has no guides.
[0093] In cases where planar motors are used in the stage driving
apparatus, either the magnet units or the armature units may be
connected to the stage, and the other of these units (magnet units
or armature units) may be connected to the side of the moving
surface of the stage. Furthermore, motors with the construction
disclosed in Japanese Patent Application Kokai No. HEI 11-27925 may
be used as planar motors.
[0094] Furthermore, the reaction force generated by the movement of
the wafer stage may be allowed to escape to the floor (ground)
mechanically by using frame members as described in (for example)
Japanese Patent Application Kokai No. HEI 8-166475. The present
invention may also be applied to wafer stages equipped with such a
reaction force treatment method.
[0095] The reaction force generated by the movement of the reticle
stage may be allowed to escape to the floor (ground) mechanically
by using frame members as described in (for example) Japanese
Patent Application Kokai No. HEI 8-330224. The present invention
may also be applied to reticle stages equipped with such a reaction
force treatment method.
[0096] The exposure apparatus in the above embodiments of the
present invention can be manufactured by assembling various types
of subsystems containing the respective constituent elements
described herein so that the specified mechanical precision,
electrical precision and optical precision are maintained. In order
to guarantee these respective types of precision, adjustments for
the purpose of achieving optical precision are performed for the
various types of optical systems, adjustments for the purpose of
achieving mechanical precision are performed for the various types
of mechanical systems, and adjustments for the purpose of achieving
electrical precision are performed for the various types of
electrical systems, before and after the above-mentioned assembly.
The process of the assembly of the various subsystems into the
exposure apparatus includes the mechanical connection of the
various subsystems to each other, the wiring connection of the
electrical circuits and the piping connection of the air pressure
circuits, etc. It goes without saying that the assembly of the
individual subsystems is performed prior to the assembly of these
various subsystems into the exposure apparatus. After the assembly
of the various subsystems into the exposure apparatus has been
completed, a comprehensive adjustment process including electrical
adjustment and checking of operations, etc., is performed, so that
the various types of precision of the exposure apparatus as a whole
are guaranteed. Furthermore, it is desirable that the manufacture
of the exposure apparatus be performed in a clean room in which the
temperature and degree of cleanness, etc., are controlled.
[0097] As is shown in FIG. 7, the semiconductor device of the
present invention is manufactured via a step S301 in which the
functions and performance of the device are designed, a step S302
in which a mask (reticle) is manufactured on the basis of this
design step, a step S303 in which a wafer is manufactured from a
silicon material, a wafer treatment step S304 in which the pattern
of the reticle is exposed on the wafer by means of the exposure
apparatus of the above-mentioned working configuration, a device
assembly step S305 (including a dicing process,bonding process and
packaging process), and an inspection step S306, etc.
[0098] Below, this device manufacturing method will be described in
even greater detail. FIG. 7 shows a flow chart which illustrates
one example of the manufacture of a device (e.g., a semiconductor
chip such as an IC of LSI, etc., liquid crystal panel, CCD,
thin-film magnetic head or micro-machine, etc.). As is shown in
FIG. 7, the design of the functions and performance of the device
(e.g., circuit design of a semiconductor device, etc.) are first
performed in step S301 (design step). Here, pattern design is
performed in order to realize the above-mentioned functions. Next,
in step S302 (mask manufacturing step), a mask (reticle) on which
the designed circuit pattern is formed is manufactured. Meanwhile,
in step S303 (wafer manufacturing step), a wafer is manufactured
using a material such as silicon, etc.
[0099] Next, in step S304 (wafer treatment step), an actual
circuit, etc., is formed on the wafer by a lithographic technique,
etc. (as will be described later), using the mask (reticle) and
wafer prepared in steps S301 through S303. Next, in step S305
(device assembly step), the device is assembled using the wafer
treated in step S304. Processes such as a dicing process, bonding
process and packaging process (chip sealing), etc., are included in
this step S305 as necessary.
[0100] Finally, in step S306 (inspection step), an inspection
including a operation checking test and durability test, etc., of
the device manufactured in step S305 is performed. Following the
completion of these processes, the device is completed, and this
device is shipped.
[0101] FIG. 8 shows one example of the detailed flow of the
above-mentioned step S304 in the case of a semiconductor device. In
FIG. 8, the surface of the wafer is oxidized in step S311
(oxidation step). An insulating film is formed on the surface of
the wafer in step S312 (CVD step). Electrodes are formed on the
wafer by vacuum deposition in step S313 (electrode formation step).
Ions are injected into the wafer in step S314 (ion injection step).
The above steps S311 through S314 constitute the pretreatment
process for respective stages of the wafer treatment. In each
stage, the necessary treatments are selected and performed.
[0102] When the above-mentioned pretreatment process is completed
in each stage of the wafer process, an after-treatment process is
performed as shown below. In this after-treatment process, the
wafer is first coated with a photosensitive agent in step S315
(resist formation step). Next, in step S316 (exposure step), the
circuit pattern of the mask (reticle) is transferred onto the wafer
using the exposure apparatus of the present working configuration.
Next, in step S317 (developing step), the exposed wafer is
developed, and in step S318 (etching step), the surface of the
exposed member in areas other than the areas where the resist
remains is removed by etching. Then, in step S319 (resist removal
step), the resist that is unnecessary following the completion of
etching is removed.
[0103] Circuit patterns are formed in multiple layers on the wafer
by repeating the above-mentioned pretreatment and
after-treatment.
[0104] As a result of being constructed as described above, the
present invention possesses the following merits.
[0105] Since the duty ratio of the PWM signal is adjusted in
accordance with fluctuations in the power supply level supplied to
the PWM control apparatus, there is no need to install a power
supply with a highly precise regulation in the power supply
circuit. For example, a power supply in which a three-phase
alternating current is merely rectified by means of diodes is
sufficient. Accordingly, an extremely great reduction in the cost
of the power supply, reduction in the volume of the power supply
and reduction in the weight of the power supply can be achieved.
Furthermore, the use of a high-precision, high-S/N-ratio PWM
control apparatus becomes possible. For example, a reduction in
cost, reduction in volume and reduction in weight can be achieved
while maintaining high-precision, high-S/N-ratio control in a motor
driving apparatus used to drive motors, a stage apparatus utilizing
this motor driving apparatus, and an exposure apparatus utilizing
this stage apparatus, etc.
[0106] It will be apparent to those skilled in the art that various
modifications and variations can be made to the present invention
without departing from the spirit or scope of the invention. Thus,
it is intended that the present invention cover the modifications
and variations of this invention provided they come within the
scope of the appended claims and their equivalents.
* * * * *