CA2059134A1 - Laser device - Google Patents
Laser deviceInfo
- Publication number
- CA2059134A1 CA2059134A1 CA 2059134 CA2059134A CA2059134A1 CA 2059134 A1 CA2059134 A1 CA 2059134A1 CA 2059134 CA2059134 CA 2059134 CA 2059134 A CA2059134 A CA 2059134A CA 2059134 A1 CA2059134 A1 CA 2059134A1
- Authority
- CA
- Canada
- Prior art keywords
- laser
- control
- light
- wavelength
- gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/10—Controlling the intensity, frequency, phase, polarisation or direction of the emitted radiation, e.g. switching, gating, modulating or demodulating
- H01S3/13—Stabilisation of laser output parameters, e.g. frequency or amplitude
- H01S3/136—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling devices placed within the cavity
- H01S3/137—Stabilisation of laser output parameters, e.g. frequency or amplitude by controlling devices placed within the cavity for stabilising of frequency
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/14—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range characterised by the material used as the active medium
- H01S3/22—Gases
- H01S3/223—Gases the active gas being polyatomic, i.e. containing two or more atoms
- H01S3/225—Gases the active gas being polyatomic, i.e. containing two or more atoms comprising an excimer or exciplex
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Lasers (AREA)
Abstract
ABSTRACT
The present invention relates to a technique which is effectively applied to the control of an oscillation wavelength and an oscillation output in a laser device. The object of the invention is to adjust an angle of inclination of a wavelength selection element such as an etalon with high accuracy to always stabilize a laser output wavelength from a laser resonator.
The present invention provides a laser device having at least first and second wavelength selection elements arranged in series on a light path, at least one angle of inclination being adjusted to form a laser light from a laser medium into a narrower band, said laser device comprising an automatic micrometer head for finely adjusting said angle of inclination.
By using an automatic micrometer head capable of finely controlling a moving amount, fine adjustment of an angle of inclination with respect to a light path of a wavelength selection element can be made. Therefore, it is possible to always stabilize a wavelength of a laser light released from a laser resonator.
Accordingly, the present invention can be effectively utilized for uses such as a light source in a lithography step in the manufacture of a semiconductor.
The present invention relates to a technique which is effectively applied to the control of an oscillation wavelength and an oscillation output in a laser device. The object of the invention is to adjust an angle of inclination of a wavelength selection element such as an etalon with high accuracy to always stabilize a laser output wavelength from a laser resonator.
The present invention provides a laser device having at least first and second wavelength selection elements arranged in series on a light path, at least one angle of inclination being adjusted to form a laser light from a laser medium into a narrower band, said laser device comprising an automatic micrometer head for finely adjusting said angle of inclination.
By using an automatic micrometer head capable of finely controlling a moving amount, fine adjustment of an angle of inclination with respect to a light path of a wavelength selection element can be made. Therefore, it is possible to always stabilize a wavelength of a laser light released from a laser resonator.
Accordingly, the present invention can be effectively utilized for uses such as a light source in a lithography step in the manufacture of a semiconductor.
Description
~ 2~13~ -SPECIFICATION
LASER DEVICE
FIELD OF AKT
The present invention relates to a technique which is effectively applied to the control of oscillation wavelength and oscillation output in a laser device.
BACKGROUND ;~
..~ :. .
A laser light itself has features such as high coherent wavelength purity, high output, etc., and is promising as a light source capable of irradiating an intense -light. Under these circumstances, there is a narrow band excimer laser which has been studied f~or use as a light source in the step of lithography in t;he manufacture of a semiconductor.
For obtaining a narrow band laser light, there has been known a laser resonator composed of wavelength selection elements such as a grating, a prism, a birefringent filter, etalon, etc.
Furthermore, ~or a laser medium which~has a laser gain in a wide band such as an excimer laser or a dye laser, the technic has been known in which one or more etalons are lnserted into a laser resonator for a narrower band.
The etalon will be briefly described. The etalon is a wavelength selection element which applies multi-reflection ;
~', .. " :.
~` 2~13~
and interference phenomenon of a light generated between two reflective films of high flatness held parallel with each other at predetermined distances.
A laser device using such an etalon as described above is shown in Fig. 6, in which a multiple narrow band is realized by a pair of first and second etalons 25a and 25b.
That is, the first etalon 25a has a function for rough adJustment of the narrower band, and the second etalon 25b `
has a function for fine adjustment thereof. More partlcular]y, a laser light irradiated from a laser medium 26 is reflected by a rear mirror 27, after which an original j ;
laser oscillation wavelength is roughly formed into a , narrower band by the first etalon 25a, and said narrower band is further narrowed, as an output, to the band width as desired by the second etalon 25b. The light is irradiated from a laser resonator 29 via a front mirror 28.
The following method has been employed in order to ; stabilize the wavelength of the laser light irradiated from , the laser resonator 29.
: :.
The light path of a laser light irradiated from the laser resonator 29 is branched by a beam splitter 30, and the branched laser light is introduced into a wavelength measuring portion 33 via an optical fiber cable 32. The center wavelength is measured by the wavelength measuring portion 33, and the thus obtained measured signal is released ~`
to a main controller 34. In the main controller 34, :~ ;. .; i . . ~ . . :
~ 2~13~ `
predetermined arithmetic processing is execu~ed accordin~ to the measured signal, and actuators 36a and 36b for changing air pressure, oil pressure or spring pressure are driven by a predetermined amount through a driving interface 35 to adJust the etalons 25a and ~5b to an optimum position.
Accordingly, it has been necessary to positively fine-ad~ust both the etalons 25a and 25b in order to stabilize the center wavelength of the laser light irradiated from the laser resonator 29.
Incidentally, in the field requiring superfine processing such as the manufacture of semiconductors, high- `
degree wavelength stability is required in the continuous irradiation for a long period of time, and a variation in ;;
center wavelength of light has to be suppressed within a range as small as possible in the narrow band. `
However, the actuators 36a and 36b relying upon the air pressure, oil pressure or spring pressure is rough in minimum operation unit. That is, it :Ls difficult to fine~
adJust an angle of inclination of the etalons 25a and 25b, thus making it difficult to obtain high-degree stability of ;, laser wavelength.
The present invention has been achieved in view of the foregoing. An object of the present invention is to provide an arrangement wherein adjustment of an angle of inclination of wavelength selection elements such as etalons is effected with high accuracy, and a laser output ''"
LASER DEVICE
FIELD OF AKT
The present invention relates to a technique which is effectively applied to the control of oscillation wavelength and oscillation output in a laser device.
BACKGROUND ;~
..~ :. .
A laser light itself has features such as high coherent wavelength purity, high output, etc., and is promising as a light source capable of irradiating an intense -light. Under these circumstances, there is a narrow band excimer laser which has been studied f~or use as a light source in the step of lithography in t;he manufacture of a semiconductor.
For obtaining a narrow band laser light, there has been known a laser resonator composed of wavelength selection elements such as a grating, a prism, a birefringent filter, etalon, etc.
Furthermore, ~or a laser medium which~has a laser gain in a wide band such as an excimer laser or a dye laser, the technic has been known in which one or more etalons are lnserted into a laser resonator for a narrower band.
The etalon will be briefly described. The etalon is a wavelength selection element which applies multi-reflection ;
~', .. " :.
~` 2~13~
and interference phenomenon of a light generated between two reflective films of high flatness held parallel with each other at predetermined distances.
A laser device using such an etalon as described above is shown in Fig. 6, in which a multiple narrow band is realized by a pair of first and second etalons 25a and 25b.
That is, the first etalon 25a has a function for rough adJustment of the narrower band, and the second etalon 25b `
has a function for fine adjustment thereof. More partlcular]y, a laser light irradiated from a laser medium 26 is reflected by a rear mirror 27, after which an original j ;
laser oscillation wavelength is roughly formed into a , narrower band by the first etalon 25a, and said narrower band is further narrowed, as an output, to the band width as desired by the second etalon 25b. The light is irradiated from a laser resonator 29 via a front mirror 28.
The following method has been employed in order to ; stabilize the wavelength of the laser light irradiated from , the laser resonator 29.
: :.
The light path of a laser light irradiated from the laser resonator 29 is branched by a beam splitter 30, and the branched laser light is introduced into a wavelength measuring portion 33 via an optical fiber cable 32. The center wavelength is measured by the wavelength measuring portion 33, and the thus obtained measured signal is released ~`
to a main controller 34. In the main controller 34, :~ ;. .; i . . ~ . . :
~ 2~13~ `
predetermined arithmetic processing is execu~ed accordin~ to the measured signal, and actuators 36a and 36b for changing air pressure, oil pressure or spring pressure are driven by a predetermined amount through a driving interface 35 to adJust the etalons 25a and ~5b to an optimum position.
Accordingly, it has been necessary to positively fine-ad~ust both the etalons 25a and 25b in order to stabilize the center wavelength of the laser light irradiated from the laser resonator 29.
Incidentally, in the field requiring superfine processing such as the manufacture of semiconductors, high- `
degree wavelength stability is required in the continuous irradiation for a long period of time, and a variation in ;;
center wavelength of light has to be suppressed within a range as small as possible in the narrow band. `
However, the actuators 36a and 36b relying upon the air pressure, oil pressure or spring pressure is rough in minimum operation unit. That is, it :Ls difficult to fine~
adJust an angle of inclination of the etalons 25a and 25b, thus making it difficult to obtain high-degree stability of ;, laser wavelength.
The present invention has been achieved in view of the foregoing. An object of the present invention is to provide an arrangement wherein adjustment of an angle of inclination of wavelength selection elements such as etalons is effected with high accuracy, and a laser output ''"
-3~
-` 2~59~31 wavelength from a laser resonator is always stabili~ed.
Further, it is desired in the laser device that the ;
laser output i5 highly stabilized. However, it is necessary to positively measure the laser output on the premise of feedback control for the stabilization of laser output.
Moreover, for the stabilization of laser output, it is necessary to cutoff noises from a power source portion, and further necessary to properly control the entire apparatus.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a ~ :, laser device which can response to the demands as noted above. For achieving the aforesaid obJect, the present invention (a first invention) provides a laser device having at least first and second wavelength selection elements which are arranged in series on a light path and in which a laser light from a laser medium is made into a narrow band by adJusting an angle of inclination of at least one wavelength selection element, said laser device comprising an automatic micrometer head for finelY ad~usting said inclination angle.
According to the aforementioned means, fine adjustment of an angle of inclination of the wavelength selection element with respect to the light path can be made by the use of an automatic micrometer head capable of finely controlling a movement amount. Therefore, the wavelength of the laser light outputted from the laser resonator can be ':
.. .. , . . . . , . .. . ~
, ~ , , , . . :
., , . , ,, , .. . ., . : .
always stabilized.
The aforementioned automatic micrometer head is an actuator having a construction in which for example, a ~C --motor, a pulse motor, etc. is used, and the rotation of such a motor is converted into linear movement to move the head.
As the wavelength selection element used in the present invention, there can be used, other than the etalon, a diffraction grating, a birefringent filter, etc.
Further, a combination of said diffraction grating and said ~- ~
etalon or a combination of the birefringent filter and the ~-etalon can be also used.
Lasers suitable for the control o~ laser oscillation output and wavelength according to the present invention include, other than excimer lasers such as KrF, ArF, etc., carbon dioxide gas laser, copper vapor laser, alexandrite laser, Ti-saphire laser, dye laser, etc.
Next, a second invention wtll be described which is intended to improve reliability of measurement of detection of laser oscillation output. An obJect of the present invention is to provide a laser device which enables accurate measurement of laser oscillation output without being affected by electromagnetlc noises from laser medium or the like, and which enables stabilized laser oscillation.
The second invention provides a laser osclllation output detection device comprising a light receiving portion arranged in the neighbourhood of a laser medium, an optical ' ~` 2~9134 ~iber having one end connected to said light receiving portion to transmit a detected light from the laser medium, a light release portion connected to the other end of the optical fiber, a photoelectric conversion element arranged opposedly of said light release portion, and a main controller which calculates an oscillation output of said laser light on the basis of a detected signal from the photoelectric conversion element to generate a control signal to said laser medium.
Lasers used herein may include not only lasers which oscillate pulses such as excimer laser such as KrF, ArF, etc., carbon dioxide gas laser, copper vapor laser, dye laser, YAG laser, alexandrite laser, etc. but also lasers for continuous oscillation such as helium~neon laser, argon ion laser, etc.
The light receiving portion arld the light release portion connected to the opposite ends of the optical fiber are provided with optical lenses, respectively, to improve in-light efficiency and out-light efficiency.
The photoelectric conversion element is, for example, an element such as a photodiode. An element having a photoelectric ef-fect which generates an electric signal corresponding to light quantities received will suffice.
According to the aforementioned means, the detected light received at the light receiving portion arranged in the neighbourhood of the laser medium is guided in the state o-f ''"
~9134 light to the optical fiber. Light is emitted from ~he light release portion provided at a position not affected by the electromagnetic noise of the laser medium, and said light is received by the photoelectric conversion elemen*.
As described above, in the present invention, the -optical flber is used to thereby determine the distance :-between the laser medium and the photoelectrlc conversion ele~ent, and a photodiode is arranged close to a drive and detection portion, whereby the influence of the electromagnetic noise from the laser medium can be suppressed.
Moreover, electric wiring from the photoelectric conversion element to the drive and detection portion can be considerably shortened.
As the result, a level of a noise signal mixed into an output signal of the photoelectric conversion element can be lowered to detect a signal not impaired by the noise. It is possible to positively control the laser device on the basis of the detected result as Just mentioned.
For the purpose of measuring a laser emission intensity of high reliability, a third invention provides a laser oscillation output detection device comprising a light receiving element for receiving a laser light, an A/D
conversion portion for converting a detected electric signal sub~ected to photoelectric-conversion by the light receiving element into a digital signal, and arithmetic means for analyzing a singnal from the A/D conversion portion to ~" ' , . . . ! , .
' " ' . ' " ' ' " ' . ' ' . ' , ' . ~ , '; ' ' . ' ' ' . " ' ' ' " ' . ' 3 ~
calculate a laser oscillation output, characterized in that an integrating circuit provided at least a multistage integrator is interposed between said light receiving element and the A~D converter.
Laser used herein may include not only pulse oscillation lasers such as excimer laser, carbon dioxide gas laser, copper vapor laser, dye laser, YAG laser, alexandrite laser, etc. but also continuous oscillation lasers such as helium/neon laser, argon ion laser, etc.
The light receiving element is a photoelectric element, for example, such as a photodiode and will suffice to be an element which generates an electric signal corresponding to received light quantities.
As the integrating circuit, an integrator can be realized by a circuit structure in which, for example, OP
amplifiers are connected in a multi-stage manner.
Preferably, oscillation wavelength of at least scores of ns can be extended to approximately scores o~ ~ s.
According to the aforementioned means, paying attention to the fact that the output waveform of the light ~-recelving element represents the time distribution o~ light intensity, this value is integrated by time to detect the ~`~
light intensity as light quantities. Therefore, more accurate detection of the light intensity can be made. ~
A fourth invention has lts ob~ect to provide a laser ;;;;
device which does not diffuse noises externally of a casing ;. .-::
2 ~ 3 ~ :
or toward a power source, and which can considerablY improve ; :
an isolation particularly between a computer and a high ~-voltage system to prevent an abnormal operation of the computer.
The fourth invention provides a laser device having a high voltage generator for supplying a high voltage to a discharge electrode within a gas laser chamber and a computer for controlling said high voltage ~enerator, said laser device comprising the following configuration.
That is, a first shield is provided on a first power source line for connecting said high voltage generator and a power source.
A noise filter is interposed halfway of the first power source line.
A second shield is provided on a second power source line for connecting a power source 3 and a computer.
A third shield is provided on a high voltage cord between said high voltage generator and the discharge electrode.
Moreover, a control llne for connecting said high voltage generator and the computer is used as an optical cable to provide a laser device.
As suitable shields as described above, there can be mentioned metal nettings and flexible convex tubes of high shieldability, which are preferably grounded.
As the noise filter, an lnsulated transformer or a _g _ : :
lowpass filter is suitable. Preferably, a shielding or fllterlng is applied to parts from which noise tends to leak.
The reflective wave from the high voltage generator is cut by a noise filter and never moves into the power source. Accordingly, spurious or pulsewise noises are not entered into the computer or other circuits through the power source. The shields are provided to prevent the noises caused by electromagnetic induction from being induced into the power source llne.
Since the computer uses the optical cable for input and output of data, isolation from noises is complete, and no -possible erroneous operation occurs.
A fifth invention has its obJect to prevent an erroneous operation during the control of a laser gas supply and exhaust system to reali2e the gas supply and exhaust control of high reliability.
The fi~th invention provides a laser-gas supply and ,.
exhaust device for supplying and exhausting a laser gas into a laser chamber, comprising a main pipe connected between a gas~source and a laser chamber to introduce the laser gas ..::
within said gas source into the chamber, a fluid pressure ~ ~-: .
driving valve provided on said main pipe and driven by fluid , ~ :
pressure via a control pipe from a remote position to open and close the main pipe, an electromagnetic valve device connected to the end of said control pipe, a pressure detector connected to the end of a branch pipe from said main ~
. .
' -10- ,~ "
f~ 3 ~
pipe, and a control portion connected by electric wiring to said electromagnetic valve device and said pressure detector to electrically control them, the piPing distance of said control pipe and said branch pipe being determined to have a sufficient length so that said electric wiring is not affected by electromagnetic noises generated in the laser chamber.
This invention is particularly characterized in that a valve for controlling the opening and closing of the main pipe is made to constitute a fluid pressure driving valve, a control pipe for supplying and e~hausting said driving fluid pressure and an electromagnetic valve device are provided, and the pressure detector is connected to the end of the branch pipe.
According to the aforesaid means, the valve for controlling the opening and closing of the main pipe is of the type driven by fluid pressure such as air not affected by the electromagnetic no~se, and the pressure detector is arranged at a position away from the laser chamber by arrangement of the branch pipe, whereby all electric wirings of the control system can be parted from the laser chamber.
Therefore, the accuracy of the detected value by the pressure detector is secured without being affected by the electromagnetic noise generated in the laser chamber.
Similarly, the valve for opening and closing the main pipe is prevented from being erroneously operated.
--11-- , -. . , . : : ~ ,.
2 ~ 3 ~
The gas supply and exhaust device having the above-described features can be generally used for the gas laser device which is not of the seal-off type.
A sixth invention has its object to provide a gas laser control device having a plurality of control items different in processing speed, in which a plurality of control items can be executed side by side by a single control device.
The sixth invention provides a gas laser control device comprising at least a high speed processing system requiring a high speed processing and a low speed processing system requiring a low speed processing, characterized in that processing timings are independently determined by a high speed timer counter for producing a reference clock for said high speed processing and a low speed timer counter for producing a reference clock for the low speed processlng.
According to the aforesaid means, a control device ~;~
is built up on the basis of an exclusive-use microprocessor (CPU), and two or more timer counters for synthesizing -optional frequencies ~rom a clock signal are freely used to thereby response to the high speed arithmetic processing as weIl as the low speed arithmetic processing. To this are added, for example, parallel input and output, I/O of digital-analog conversion and analog-digital conversion and light input and output ports to constitute a system.
Further, a time-division system is incorporated in a software .:
, : : . . ~: . , :. . . " .: ...
~ 2~13~
and a low speed control processing is incorporated into a high speed control processing, whereby the side by side processing of a plurallty of control items can be made. As the result, for example, the laser oscilla~ion required for the high speed processing is not stopped, and other low speed controls such as the exchange of gas can be executed.
In the sixth invention, the control items in the high speed processing system include at least an output of a discharge start signal, an output for detection of a laser output and a control signal for the stabilization thereof, and an output of detection of a laser wavelength and a control signal for the stabilization thereof. The control items in the low speed processing system desirably includes at least an output of a signal for controlling the opening and closing of a gas valve in the exchange of gas.
Two or more of first to sixth inventions described above are selectively combined and can be incorporated into the laser device.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 to 5 show one embodiment of the present invention (a first invention). Fig. 1 is a block diagram showing the whole structure of a laser device, Fig. 2(a) shows an etalon holder for explaining adjusting means of a wavelength selection element as viewed ln a direction of A of Fig. 2(b), Fig. 2(b) is a side view of the same, and Fig. 3 is an explanatory view showing the stabilizing - : . . . . .- : , , , : . . , ~
:,. ' : , ~ ~
,~ 2~5~3~
control of a center wavelength. Fig. 4 is a view showing one example of an automatic micrometer head. Fig. 5 is a block diagram of a main control section. Fig. 6 is a block diagram showing the whole structure of a laser device according to prior art.
Fig. 7 is a block diagram showing the structure of a laser oscillation output detection device according to one embodiment of a second invention. -Figs. 8 to 10 show one embodiment according to a third invention. Eig. 8 is a block diagram showing the structure of a laser oscillation output detection device, Figs. 9(a) and 9(b) are respectively explanatory views showing a li~ht receiving element and an output waveform in an integrating circuit, and Fig. 10 is a circuit view showing the detailed structure of the integrating circuit.
; Figs. 11 and 12 ~how an embodiment according to a fourth invention. Fig. 11 is a block diagram of the whole structure, and Fig. 12 is a block diagram of a computer section.
Fig. 13 is a block diagram showing a laser gas supply and exhaust device according to one embodiment of a fifth invention.
Fig. 14 is a block diagram showing the structure of a gas laser control device according to one embodiment of a sixth in~ention.
BEST MODE FOR CARRYING OUT THE INVENTION
'`.
2~ 3~
Embodiments of the present invention will be described hereinbelow with reference to the drawings.
In the present invention (a first invention), a roughly adJusting etalon 3 and a finely adjusting etalon 4 as a wavelength selection element are arranged outwardly of one end of a laser medium 2, as shown in Fig. 1. A rear mirror 5 is arranged on the outermost side of the laser medium so that a laser light produced by the laser medium 2 is reflected by the rear mirror 5 and thereafter narrowed into a wavelength band of approximately ljlO by the roughly adjusting etalon 3 and further narrowed into approximately 1/10 thereof by the finely adjusting etalon 4. The light then radiated outside via a front mirror 1.
The thus radiated laser light is branched in light path by a beam splitter 6 arranged on the light path, and the light enters a wavelength measuring section 8 from an optical fiber cable 7, and the oscillation wavelength thereof is detected. A main control section 10 for receiving the detected signal performs a predetermined arithmetic processing to output a control signal to a DC motor driver 11. `:
The DC motor driver 11 finely adJusts the roughly ad~usting ~ :
etalon 3 and the finely adJusting etalon 4 in accordance with the control signal. Such a fine adjustment as described is accomplished by driving automatic micrometer heads 14a to 14d.
The aforesaid fine ad~ustment technique will be , 3 ~
described with re~erence to Fig. 2.
Each pair of the automatic micrometer heads 14a to 14d are arranged on one diagonal line on planes o~ and wi$h respect to rectangular etalon holders 15 and 16 for holding the eta]ons 3 and 4, comprising the automatic micrometer heads 14a and 14d for -finely ad~usting a lateral deviation -o~ the etalons 3 and 4 and the automatic micrometer heads 14b and 14c ~or finely ad~usting an angle of inclination with respect to the light path of the etalon. The automatic micrometer heads 14a to 14d are independently driven by the DC motor driver 11 according to the control signal from the main control section 10.
The automatic micrometer heads 14a to 14d will be -brlefly explained. The automatic micrometer head is internally provided with a supersmall DC motor DC drive means and a gear head o~ high resolving power, said gear head being connected to a lead screw rotated by a motor, and the rotation of the motor 1s converted into the movement in a linear direction o~ the lead screw.
For example, as shown in Fig. 4, a casé 20a for the automatic micrometer head is interiorly provided with a linear slide head 20b, a lead screw 20c, a gear head 20d of h~gh resolving power, and a supersmall DC motor 20e, said supersmall DC motor 20e being controlled by the main control section 10.
The linear slide head 20b has a rod-like portion 20 ~ .
at one end thereof which proJects from ~he case 20a and a cylindrical portion 20g at the other end thereof which is internally formed with internal threads 20h. The lead screw 20c is in the form of a rod, which is inserted into a cylindrical portion 20g of the linear slide head 20b and -formed in its peripheral surface with external threads 20i meshed with the external threads 20h.
The gcar head 20d oY high resolving power performs the torque conversion of the DC motor 20e with a combination of gears not shown. The main control section 10 controls the rotational amount and rotational speed of the DC motor 20e.
More specifically, as shown in Fig. 5, the main control section 10 comprises a target value setting means 21 for setting a reference ce~ter wavelength of a narrower band spectrum, a deviation detection means 22 for detecting a deviation of the measured center wavelength detected by the wavelength measuring section 8 to the reference center wavelength set by the target value setting means 21, and control means 23 for sending a signal for controlling the rotatlonal amount and rotational speed of the DC motor to the automatic micrometer head in a direction of negating the deviation detected by the deviation detection means 22.
As previously mentioned. the automatic micrometer head is composed of the automatic micrometer heads 14a and 14d for finely ad~usting the lateral deviation and the automatic micrometer heads 14b and 14c for finely adjusting '~,.
-17- ~
, , ., . ~ :: :
. : .~ : . ,:: ... .
2 ~ 3 ~ `
the angle o-~ inclination. The fine adJustment of the angle of inclination comprises an important element for the stabilizing control o~ the wavelength. The use of the a~oresaid automatic micrometer heads enables the highly ~;
accurate fine ad~ustment of the angle of inclination, say, 0.04 mrad/sec.
Next, the concrete stabilizing control of the wavelength using the present device will be described.
In the stabilizing control of the wavelength according to the present embodiment, first, the target value setting means 21 determines a reference center wavelength of a narrower spectrum as a target. In the case where the measured center wavelength detected by the wavelength measuring section 8 is deviated ~rom the aforesaid reference center wavelength, the deviation detection means 22 detects the deviation, and it is controlled so that the deviation is overcome by a control signal (a feedback signal) -from the control means 23 of the main control section 10.
That is, as shown in Fig. 3, a reference center wavelength lo as desired of the laser light ls determined ;~
while monitoring the wavelength measuring section 8, and ~ ;
under this condition, the DC motor driver 11 is locked to ~`~
temporarily fix both the etalons 3 and 4.
Next, the laser light irradiated from a laser resonator 9 is measured with the lapse o~ time by the wavelength measuring section 8. When the measured center wavelength is ~..
-- 2 ~ 3 ~
,.
deviated by ~ l from the reference center wave:length, the main control section 10 outputs a control signal for finely ad~usting the position on the light path to the etalons 3 and 4 to the DC motor driver 11. That is, out of four automatic micrometer heads 14a to 14d, the automatic micrometer head 14d for controlling an angle of inclination of the finely ad~usting etalon 4 is principally driven to finely adJust the angle of inclination.
At this time, the DC motor within the automatic micrometer head 14d is rotated through a predetermined amount -clockwise or counterclockwise depending on the fact that said deviation of ~ A is on the short wavelength side (- direction) or on the long wavelength side (+ direction).
Control parameters in the main control section 10, for example, such as the rotational direction, driving speed and driving time of the DC motor are registered in advance in a predetermined address of a memory area of the main control section 10.
The stabilizing experiment for the center wavelength by the aforementloned apparatus was conducted using one dimensional photodiode array in the procedure in which the -apparatus is operated for one hour at 80 Hz to measure the state of variation of the measured center wavelength. As the result, the wavelength stability whose variation width of the center wavelength is + 0.57 pm.
An automatic micrometer head with an encoder for . ' ' ' '' ' ' ' ,. ~ ' '' '". ' ' :. : ~
, 20S~3~
detecting the rotational amount of the motor may be used.
In this automatic micrometer head, an encoder is arranged between a spindle and a gear head so as not to count lost motion (unnecessary movement) or backlash (reverse rotation). ~ `
An example o~ a second invention, which is intended to improve the reliability of measurement in the detection of laser oscillation output, will be described below.
In Fig. 7, a laser light 103 emitted from an outlet 102 o~ a laser resonator 101 having a laser medium is partly branched by a beam splitter 104, and the branched light enters a light receiving section 105. The laser light 103 is guided to a light release section 107 at a position of a predetermined distance ~ via an optical fiber 106 connected to the light receiving section 105.
Pre~erably, the predetermined distance ~ is determined by, for example, the outpu1; standard of the laser medium 2 itself.
A photodiode as a photoelectric conversion element 110 is arranged at a position opposed to the light release ~;
section 107 through an ND ~ilter 108. At the photodiode, an output voltage is varied according to the light intensity ~rom the light release section 107.
In a drive and detection section 111, a voltage signal from the photodlode is sub~ecSed to signal processing ~ -such as A/D conversion and outputted to a control section , .
112.
~: , : r_ The control section 112 is composed of a micro-processor, a memory, etc. so that predetermined arithmetic processing is carried out according to a measured signal from the drive and detection section 111 to produce a control signal for a laser resonator 101. This control signal is delivered to the laser resonator 101 or a laser control meehanism not shown through a control line 113 to eontrol the intensity of the laser light emitted from the laser resonator 101 .
As the method for produeing a eontrol signal, there ean be mentioned a method which eomprises storing in a memory ideal control parameters obtained by sampling ln advance to be paired with the light intensity, and sequentially changing said eontrol parameters in response to the signal from the drive and deteetion seetion 111.
In the present embodiment, the distance between the laser resonator 101 and the photoeleetrie eonversion element 110 ean be sufficiently secured by the optieal fiber 106, and therefore, the photoelectrie conversion element 110 ean be arranged in the proximity of the drive and detection section 111. Thus, the in~luence of the electromagnetic noise generated in the laser resonator 101 can be minimized.
Moreover, an electric wiring 114 from the photoelectric conversion element 110 to the drive and detection section 111 ean be eonsiderably shortened.
As the result, a level of the noise signal mixed into 2~13~
..
the output signal of the photoelectric conversion element 110 can be lowered to detect a signal not impeded by the noise, and a precise control signal can be produced in the control section 112.
According to the present invention, the signal not impeded by the noise can be detected with the result that a stabilized laser output can be obtained by the control of $he laser device.
A third invention will be described hereinbelow.
As shown in Fig. 8, a laser light 203 emitted from an outlet 202 of a laser resonator 201 having a laser medium is partly branched by a beam splitter 204, and the branched light enters a light receiving element 205. A pulse detection signal sub~ected to photoelectr~c conversion by the light receiving element 205 is converted into a digital signal by an A/D conversion section 207 and enters a control section 208 after the pulse detection signal is sub~ected to ad~ustment of wavelength by an integrating circuit 206. The control section 208 is composedr for example, of a CPU
provided with arithmetic means, a register, etc., and an external memor~ device such as a memory, so that predetermined arithmetlc processing has been executed on the basis of a pulse detection signal, after which a control signal with respect to the laser resonator 201 is produced.
This control signal is outputted to the laser resonator 201 or a laser control mechanism not shown through a control ::~
~ 20~9134 line 2]0 to control the intensitY of the laser light emitted from the laser resonator 201.
The eonerete strueture of the integrating circuit 206 which eonstitutes a feature of the present embodiment will be deseribed hereinafter.
The integrating cireuit 206 is eomposed principally of four OP amplifiers 211a, 211b, 211c and 211d as shown in Fig.
10, among which the first OP amplifier 211a has a function as an amplification stage whose amplification degree is varied by seleeting a resistance value between (-) input and earth.
A pulse detection signal is integrated by th~ second to fourth OP amplifiers 211b, 211c and 211d.-In the second and third OP amplifiers 211b and 211cin Fig. 10, an input terminal is in an imaglnary short state, and condensers of 150 pF are charged to an input voltage and initial values are applied to the respective integrators to e~eet ealeulation.
As the above-deseribed OP amplifiers, those having a band width of 8.0 MHz and having a responsiveness whose through rate is about 25 V/~ s can be used.
The integrating eireuit 206 ls eonstituted by the multi-stage integrator as described above to thereby provlde a signal shown in Flg. 9(b) obtained by extending rise/attenuation time of a detection pulse signal of the order of scores o~ ns as shown in Fig. 9(a) to the order o~
seores of ~ s. Aecordingly, a pulse deteetion signal -~3-2~59~3~
corresponding to the responsive speed to the A/D conversion section 7 can be obtained to enable accurate detection of light intensity.
According to the present embodiment, since four OP
amplifiers are used to constitute the integating circuit 206, the integration of the pulse detection signal can be made without degrading the temperature characteristics of the integrating circuit 206 even in use for long periods.
According to the present invention, paying attention to the fact that the output waveform of the light receiving element represents the time distribution of light intensity, this value is integrated with respect to time to detect the light intensity as light quantities, and therefore, accurate detection of light intensity can be made.
An embodiment o~ a fourth invention will be described hereinafter with reference to Figs. 11 and 12.
A gas laser chamber 310 is interiorly provided with a discharge electrode 311. A gas control device 321 is connected to the gas laser chamber 310 through a pipe 320, and a gas cylinder 323 is connected to the gas control device 321 through a pipe 322. Thereby, a mixed gas composed of the aforementioned components is filled into the gas laser ~;
chamber 310. A high voltage generator 301 is connected to the discharge electrode 311 through a high voltage cord 312, and a third shield 313 is provided around the high voltage cord 312. The voltage o~ the high voltage generator 301 is -2~-2 ~ 3 ~
controlled by a computer 302. The high voltage generator 301 is connected to a power source 303 through a first power source line 304, and a ~irst shield 305 is provided on the first power source line 304. An insulating trans~ormer as a noise filter 306 is provided halfway o~
the first power source line 304.
Furthermore, a second shield 308 is provided on second power source line 7 for connecting the power source 3 and a computer 302.
A control line between the high voltage generator 301 and the computer 302 is comprised of an optical cable 9. An interface between the optical cable 309 and the computer 302 is as shown in Fig. 2, in which the optical cable 309 is first inputted into an optical MODEM 302a and connected to an MPU 302c through an input and output circuit 302b. RAM 302d and ROM 302e are connected to the MPU 302c.
The MPU 302c is shielded by a single Imember.
A valve actuator (not shown) within the gas control device 321 is also controlled by the computer 302, and a control line 324 also is comprised of an optical cable. A
shield 326 is applied also to a power source line 325 for connecting the gas control device 321 and the power source 303. ; -The gas laser chamber 310. high voltage generator 301, computer 302, noise filter 306 and gas control device 321 are encased in a casing (K), said casing K and said ' 9 1 ~ ~ ~
:
shields being grounded at GND.
With the structure as described above, a noise in a power source line system and a noise in a radiation system can be suppressed and prevented. That is, the noise in the power source line system enters the power source 303 with a reflective voltage wave generated in the discharge electrode 311 passing through the high voltage generator 301, from which power source the noise leaks toward various parts but the reflected component is absorbed by the noise filter 306 and does not reach the power source 303. The noise in the radiation system does not reach the power source line due to the provision o-~ the shields.
As describe~ above, the stability and reliability of operation can be secured.
According to the present invention, the shield is applied to the power source line to be a noise source and the noise filter is provided on the high voltage power source line. Therefore, noises which leak into the external portion of the casing and into the power source can be considerably suppressed.
Furthermore, since the high voltage generator and the computer for controlling the same are connected by the optical chble, the isolation therebetween is improved, and the abnormal operation of the computer can be prevented.
A ~ifth invention will be described hereinafter.
- Fi~. 13 is a structural view of a laser gas supply ~ .
' 2i~5913~
and exhaust device according to an embodiment of the present t invention. In this figure, an examp:Le of a device in connection with an excimer laser is illustrated for an explanation.
In Fig. 13, a laser chamber 401 is connected to a gas source 402 by a main pipe 403, and buffer gas, rare gas and halogen gas etc. can be supplied into the laser chamber 401.
Valves 404a to 404c driven by ~luid pressure are provided halfway of the main pipe 403 for supplying the gases so as to adjust the mixing ratio of the gases. An exhaust pipe 406 connected to a vacuum 405 is branched from the main pipe 403, and a valve 404d driven by fluid pressure ls provided halfway of the exhaust pipe 406 The aforesaid valves 404a to 404d driven by fluid pressure are driven by the pressure of a fluld such as air to open and close~the main pipe 403 and the exhaust pipe 406. The valves are designed so that a linear motion caused by increase or decrease of air pressure 1s converted into a rotational motion o~ the valve by, Eor example, an actuator or the ~ike.
Control pipes 407a to 407d for supplying air pressure are connected to the valves 404a to 404d, respectively, said control pipes 407a to 407d being moved by a predetermined distance L and connected to an electromagnetic unit 8 for controlling a supply of air.
A branched pipe 410 is extended in the midst of the main pipe 403 from the valves 404a to 404d to the laser .:
` 2~c~ 3~
chamber 401. The branched pipe 410 is moved by a predetermined distance L and connected to a pressure detector 411. The pressure detector 411 can detect the state of pressure within the main pipe 403, that is, within the laser chamber 401.
The vacuum pump 405, the electromagnetic valve unit 408 and the pressure detector 411 are connected to the control section 412 so that their operation is controlled. .
The control section 412 is composed of a microprocessor provided with, for example, a memory or the like, in which the electromagnetic unit 408 is controlled on the basis of the detected value of the pressure detector 411 to adjust the opening and closing degree of the valves 404a.to 404d so as to control the state of pressure within the laser chamber 401.
As described above, according to the present .
embodiment, the valve mechanism for opening and closing the main pipe 403 ls of the fluid pressure drive and the pressure detector 411 is connected to the branched pipe 410 which is ;
branched and moved by from the main pipe 403 whereby the .
control system for the vacuum pump 405, the electromagnetic valve unit 408, the pressure detector 411 and the like can be parted from the laser chamber 401, and all the ele:ctric wirings can be executed at a position away -from the laser chamber 401. Therefore, the control of gas supply and `~
exhaust can be made without being affected by the :.
electromagnetic noise generated in the laser chamber 401.
:.
-28- . :
. , . .. . ~ , -` 2~13~ :
Preferably, the distance L parted from the e~haust pipe 406, the control pipes 407a to 407d and the branched pipe 410 is the distance as short as possible as needed to such a degree that the vacuum pump 405, the electromagnetic valve unit 408 and the pressure detector 411 are not affected by the electromagnetic noise from the laser chamber 401.
That is, when the distance is long, lowering of detection accuracy, lowering of drive response or the like possibly occur.
According to the present invention, the lnfluence of the electromagnetic noise in the gas laser can be reduced to prevent malfunction of the gas supply and exhaust system.
An embodiment of a sixth invention will be described hereinbelow w1th reference to a block dia~ram shown in Fig.
14 showing the structure of a gas laser control device.
In Fig. 14, reference numeral 501 designates CPU o~
16 bit system or 32 bit system. A high speed processing system such as an output wavelength monitor device 509, a laser high voltage power source 510, etc. and a low speed processing system such as a gas processing system 511 are controlled according to the command ~rom the CPU 501. j, , An output signal from the CPU 501 is outputted to a high speed timer counter 502 and a low speed timer counter ~-503. These timer counters 502 and 503 independently count clock signals CL from the CPU 501 to produce a predetermined high speed clock signal and low speed clock signal.
~':
` 2~13~
A wavelength monitor control signal and a voltage settlng eontrol signal out of outputs o-f the high speed timer counter 502 are converted into digital optical signals via D/A eonverters 504 and 505 and photoelectric converters 507a and 507b, and the digital optieal signals are again eonverted into digital electric signals v~a optical fiber cables 508a and 608b and photoeleetrie eonverters 507a and 507b to eontrol the output wavelength monitor deviee 509 and the laser output high voltage power souree 510. The eontrol timing therefor is given by a timing trigger signal whieh is produeed by a parallel TTL output deviee 508a on the basis of a high speed eloek signal from the high speed timer eounter 502 and passing through the photoeleetric eonverter 507e, the optieal fiber eable 508e and the photoelectric converter 507c in named order.
On the other hand, an output from the low speed timer counter 503 is converted into a digital optical signal via a parallel TTL output deviee 506b and a photoeleetric converter 507d and is again converted into a digital electric signal via an optieal fiber eable 508d and a photoelectric converter 507d and thenee delivered to a gas proeessing system 511 ineluding a laser ehamber. The gas proeessing system 511 executes the gas replaeing wor~ or the like with a gas valve opening and elosing signal or a vaeuum pump ON/OFF signal.
As described above, in the present embodiment, a time reference of monitor eontrol of an output waveform and ,, . ., ~
.. ~, . : :. . : :
`"` 2 ~ 3 ~
laser output control requiring high speed arithmetic processing is produced by the high speed processing timer counter 502, whereas a time re~erence of gas replacing control or the like requiring low speed arithmetic processing is produced by the low speed processing timer counter 503.
As described above, two kinds of time references whlch are greatly different from each other are independently counted by the individual timer counters to enable realization of a plurality of parallel controls without stopping any of controls. -Moreover, according to the present embodiment, there is an effect in that the control slgnal is made to pass through the optical fiber cables 508a to 508d whereby the influence of the electromagnetic noises generated *rom the laser chamber or other driving systems can be reduced to prevent malfunction of the control system.
According to the present invention, the control on the basis of a plurality of time references can be made by a single control device.
INDUSTRIAL APPLICABILITY
According to the present invention, the fine ad~ustment of the wavelength selection element can be made with high accuracy, and as a result, the output waveform in the laser resonator can be greatly stabilized.
Accordingly, the present invention can be effectively utilized for uses such as a light source in a lithography ' 3 ~
step ln the manufacture of a semiconductor.
.
;~ :- :-.
~ .~
.
:
.
.. . . . , ::
.: . . . . : .: . . , . ~ :
-` 2~59~31 wavelength from a laser resonator is always stabili~ed.
Further, it is desired in the laser device that the ;
laser output i5 highly stabilized. However, it is necessary to positively measure the laser output on the premise of feedback control for the stabilization of laser output.
Moreover, for the stabilization of laser output, it is necessary to cutoff noises from a power source portion, and further necessary to properly control the entire apparatus.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a ~ :, laser device which can response to the demands as noted above. For achieving the aforesaid obJect, the present invention (a first invention) provides a laser device having at least first and second wavelength selection elements which are arranged in series on a light path and in which a laser light from a laser medium is made into a narrow band by adJusting an angle of inclination of at least one wavelength selection element, said laser device comprising an automatic micrometer head for finelY ad~usting said inclination angle.
According to the aforementioned means, fine adjustment of an angle of inclination of the wavelength selection element with respect to the light path can be made by the use of an automatic micrometer head capable of finely controlling a movement amount. Therefore, the wavelength of the laser light outputted from the laser resonator can be ':
.. .. , . . . . , . .. . ~
, ~ , , , . . :
., , . , ,, , .. . ., . : .
always stabilized.
The aforementioned automatic micrometer head is an actuator having a construction in which for example, a ~C --motor, a pulse motor, etc. is used, and the rotation of such a motor is converted into linear movement to move the head.
As the wavelength selection element used in the present invention, there can be used, other than the etalon, a diffraction grating, a birefringent filter, etc.
Further, a combination of said diffraction grating and said ~- ~
etalon or a combination of the birefringent filter and the ~-etalon can be also used.
Lasers suitable for the control o~ laser oscillation output and wavelength according to the present invention include, other than excimer lasers such as KrF, ArF, etc., carbon dioxide gas laser, copper vapor laser, alexandrite laser, Ti-saphire laser, dye laser, etc.
Next, a second invention wtll be described which is intended to improve reliability of measurement of detection of laser oscillation output. An obJect of the present invention is to provide a laser device which enables accurate measurement of laser oscillation output without being affected by electromagnetlc noises from laser medium or the like, and which enables stabilized laser oscillation.
The second invention provides a laser osclllation output detection device comprising a light receiving portion arranged in the neighbourhood of a laser medium, an optical ' ~` 2~9134 ~iber having one end connected to said light receiving portion to transmit a detected light from the laser medium, a light release portion connected to the other end of the optical fiber, a photoelectric conversion element arranged opposedly of said light release portion, and a main controller which calculates an oscillation output of said laser light on the basis of a detected signal from the photoelectric conversion element to generate a control signal to said laser medium.
Lasers used herein may include not only lasers which oscillate pulses such as excimer laser such as KrF, ArF, etc., carbon dioxide gas laser, copper vapor laser, dye laser, YAG laser, alexandrite laser, etc. but also lasers for continuous oscillation such as helium~neon laser, argon ion laser, etc.
The light receiving portion arld the light release portion connected to the opposite ends of the optical fiber are provided with optical lenses, respectively, to improve in-light efficiency and out-light efficiency.
The photoelectric conversion element is, for example, an element such as a photodiode. An element having a photoelectric ef-fect which generates an electric signal corresponding to light quantities received will suffice.
According to the aforementioned means, the detected light received at the light receiving portion arranged in the neighbourhood of the laser medium is guided in the state o-f ''"
~9134 light to the optical fiber. Light is emitted from ~he light release portion provided at a position not affected by the electromagnetic noise of the laser medium, and said light is received by the photoelectric conversion elemen*.
As described above, in the present invention, the -optical flber is used to thereby determine the distance :-between the laser medium and the photoelectrlc conversion ele~ent, and a photodiode is arranged close to a drive and detection portion, whereby the influence of the electromagnetic noise from the laser medium can be suppressed.
Moreover, electric wiring from the photoelectric conversion element to the drive and detection portion can be considerably shortened.
As the result, a level of a noise signal mixed into an output signal of the photoelectric conversion element can be lowered to detect a signal not impaired by the noise. It is possible to positively control the laser device on the basis of the detected result as Just mentioned.
For the purpose of measuring a laser emission intensity of high reliability, a third invention provides a laser oscillation output detection device comprising a light receiving element for receiving a laser light, an A/D
conversion portion for converting a detected electric signal sub~ected to photoelectric-conversion by the light receiving element into a digital signal, and arithmetic means for analyzing a singnal from the A/D conversion portion to ~" ' , . . . ! , .
' " ' . ' " ' ' " ' . ' ' . ' , ' . ~ , '; ' ' . ' ' ' . " ' ' ' " ' . ' 3 ~
calculate a laser oscillation output, characterized in that an integrating circuit provided at least a multistage integrator is interposed between said light receiving element and the A~D converter.
Laser used herein may include not only pulse oscillation lasers such as excimer laser, carbon dioxide gas laser, copper vapor laser, dye laser, YAG laser, alexandrite laser, etc. but also continuous oscillation lasers such as helium/neon laser, argon ion laser, etc.
The light receiving element is a photoelectric element, for example, such as a photodiode and will suffice to be an element which generates an electric signal corresponding to received light quantities.
As the integrating circuit, an integrator can be realized by a circuit structure in which, for example, OP
amplifiers are connected in a multi-stage manner.
Preferably, oscillation wavelength of at least scores of ns can be extended to approximately scores o~ ~ s.
According to the aforementioned means, paying attention to the fact that the output waveform of the light ~-recelving element represents the time distribution o~ light intensity, this value is integrated by time to detect the ~`~
light intensity as light quantities. Therefore, more accurate detection of the light intensity can be made. ~
A fourth invention has lts ob~ect to provide a laser ;;;;
device which does not diffuse noises externally of a casing ;. .-::
2 ~ 3 ~ :
or toward a power source, and which can considerablY improve ; :
an isolation particularly between a computer and a high ~-voltage system to prevent an abnormal operation of the computer.
The fourth invention provides a laser device having a high voltage generator for supplying a high voltage to a discharge electrode within a gas laser chamber and a computer for controlling said high voltage ~enerator, said laser device comprising the following configuration.
That is, a first shield is provided on a first power source line for connecting said high voltage generator and a power source.
A noise filter is interposed halfway of the first power source line.
A second shield is provided on a second power source line for connecting a power source 3 and a computer.
A third shield is provided on a high voltage cord between said high voltage generator and the discharge electrode.
Moreover, a control llne for connecting said high voltage generator and the computer is used as an optical cable to provide a laser device.
As suitable shields as described above, there can be mentioned metal nettings and flexible convex tubes of high shieldability, which are preferably grounded.
As the noise filter, an lnsulated transformer or a _g _ : :
lowpass filter is suitable. Preferably, a shielding or fllterlng is applied to parts from which noise tends to leak.
The reflective wave from the high voltage generator is cut by a noise filter and never moves into the power source. Accordingly, spurious or pulsewise noises are not entered into the computer or other circuits through the power source. The shields are provided to prevent the noises caused by electromagnetic induction from being induced into the power source llne.
Since the computer uses the optical cable for input and output of data, isolation from noises is complete, and no -possible erroneous operation occurs.
A fifth invention has its obJect to prevent an erroneous operation during the control of a laser gas supply and exhaust system to reali2e the gas supply and exhaust control of high reliability.
The fi~th invention provides a laser-gas supply and ,.
exhaust device for supplying and exhausting a laser gas into a laser chamber, comprising a main pipe connected between a gas~source and a laser chamber to introduce the laser gas ..::
within said gas source into the chamber, a fluid pressure ~ ~-: .
driving valve provided on said main pipe and driven by fluid , ~ :
pressure via a control pipe from a remote position to open and close the main pipe, an electromagnetic valve device connected to the end of said control pipe, a pressure detector connected to the end of a branch pipe from said main ~
. .
' -10- ,~ "
f~ 3 ~
pipe, and a control portion connected by electric wiring to said electromagnetic valve device and said pressure detector to electrically control them, the piPing distance of said control pipe and said branch pipe being determined to have a sufficient length so that said electric wiring is not affected by electromagnetic noises generated in the laser chamber.
This invention is particularly characterized in that a valve for controlling the opening and closing of the main pipe is made to constitute a fluid pressure driving valve, a control pipe for supplying and e~hausting said driving fluid pressure and an electromagnetic valve device are provided, and the pressure detector is connected to the end of the branch pipe.
According to the aforesaid means, the valve for controlling the opening and closing of the main pipe is of the type driven by fluid pressure such as air not affected by the electromagnetic no~se, and the pressure detector is arranged at a position away from the laser chamber by arrangement of the branch pipe, whereby all electric wirings of the control system can be parted from the laser chamber.
Therefore, the accuracy of the detected value by the pressure detector is secured without being affected by the electromagnetic noise generated in the laser chamber.
Similarly, the valve for opening and closing the main pipe is prevented from being erroneously operated.
--11-- , -. . , . : : ~ ,.
2 ~ 3 ~
The gas supply and exhaust device having the above-described features can be generally used for the gas laser device which is not of the seal-off type.
A sixth invention has its object to provide a gas laser control device having a plurality of control items different in processing speed, in which a plurality of control items can be executed side by side by a single control device.
The sixth invention provides a gas laser control device comprising at least a high speed processing system requiring a high speed processing and a low speed processing system requiring a low speed processing, characterized in that processing timings are independently determined by a high speed timer counter for producing a reference clock for said high speed processing and a low speed timer counter for producing a reference clock for the low speed processlng.
According to the aforesaid means, a control device ~;~
is built up on the basis of an exclusive-use microprocessor (CPU), and two or more timer counters for synthesizing -optional frequencies ~rom a clock signal are freely used to thereby response to the high speed arithmetic processing as weIl as the low speed arithmetic processing. To this are added, for example, parallel input and output, I/O of digital-analog conversion and analog-digital conversion and light input and output ports to constitute a system.
Further, a time-division system is incorporated in a software .:
, : : . . ~: . , :. . . " .: ...
~ 2~13~
and a low speed control processing is incorporated into a high speed control processing, whereby the side by side processing of a plurallty of control items can be made. As the result, for example, the laser oscilla~ion required for the high speed processing is not stopped, and other low speed controls such as the exchange of gas can be executed.
In the sixth invention, the control items in the high speed processing system include at least an output of a discharge start signal, an output for detection of a laser output and a control signal for the stabilization thereof, and an output of detection of a laser wavelength and a control signal for the stabilization thereof. The control items in the low speed processing system desirably includes at least an output of a signal for controlling the opening and closing of a gas valve in the exchange of gas.
Two or more of first to sixth inventions described above are selectively combined and can be incorporated into the laser device.
BRIEF DESCRIPTION OF THE DRAWINGS
Figs. 1 to 5 show one embodiment of the present invention (a first invention). Fig. 1 is a block diagram showing the whole structure of a laser device, Fig. 2(a) shows an etalon holder for explaining adjusting means of a wavelength selection element as viewed ln a direction of A of Fig. 2(b), Fig. 2(b) is a side view of the same, and Fig. 3 is an explanatory view showing the stabilizing - : . . . . .- : , , , : . . , ~
:,. ' : , ~ ~
,~ 2~5~3~
control of a center wavelength. Fig. 4 is a view showing one example of an automatic micrometer head. Fig. 5 is a block diagram of a main control section. Fig. 6 is a block diagram showing the whole structure of a laser device according to prior art.
Fig. 7 is a block diagram showing the structure of a laser oscillation output detection device according to one embodiment of a second invention. -Figs. 8 to 10 show one embodiment according to a third invention. Eig. 8 is a block diagram showing the structure of a laser oscillation output detection device, Figs. 9(a) and 9(b) are respectively explanatory views showing a li~ht receiving element and an output waveform in an integrating circuit, and Fig. 10 is a circuit view showing the detailed structure of the integrating circuit.
; Figs. 11 and 12 ~how an embodiment according to a fourth invention. Fig. 11 is a block diagram of the whole structure, and Fig. 12 is a block diagram of a computer section.
Fig. 13 is a block diagram showing a laser gas supply and exhaust device according to one embodiment of a fifth invention.
Fig. 14 is a block diagram showing the structure of a gas laser control device according to one embodiment of a sixth in~ention.
BEST MODE FOR CARRYING OUT THE INVENTION
'`.
2~ 3~
Embodiments of the present invention will be described hereinbelow with reference to the drawings.
In the present invention (a first invention), a roughly adJusting etalon 3 and a finely adjusting etalon 4 as a wavelength selection element are arranged outwardly of one end of a laser medium 2, as shown in Fig. 1. A rear mirror 5 is arranged on the outermost side of the laser medium so that a laser light produced by the laser medium 2 is reflected by the rear mirror 5 and thereafter narrowed into a wavelength band of approximately ljlO by the roughly adjusting etalon 3 and further narrowed into approximately 1/10 thereof by the finely adjusting etalon 4. The light then radiated outside via a front mirror 1.
The thus radiated laser light is branched in light path by a beam splitter 6 arranged on the light path, and the light enters a wavelength measuring section 8 from an optical fiber cable 7, and the oscillation wavelength thereof is detected. A main control section 10 for receiving the detected signal performs a predetermined arithmetic processing to output a control signal to a DC motor driver 11. `:
The DC motor driver 11 finely adJusts the roughly ad~usting ~ :
etalon 3 and the finely adJusting etalon 4 in accordance with the control signal. Such a fine adjustment as described is accomplished by driving automatic micrometer heads 14a to 14d.
The aforesaid fine ad~ustment technique will be , 3 ~
described with re~erence to Fig. 2.
Each pair of the automatic micrometer heads 14a to 14d are arranged on one diagonal line on planes o~ and wi$h respect to rectangular etalon holders 15 and 16 for holding the eta]ons 3 and 4, comprising the automatic micrometer heads 14a and 14d for -finely ad~usting a lateral deviation -o~ the etalons 3 and 4 and the automatic micrometer heads 14b and 14c ~or finely ad~usting an angle of inclination with respect to the light path of the etalon. The automatic micrometer heads 14a to 14d are independently driven by the DC motor driver 11 according to the control signal from the main control section 10.
The automatic micrometer heads 14a to 14d will be -brlefly explained. The automatic micrometer head is internally provided with a supersmall DC motor DC drive means and a gear head o~ high resolving power, said gear head being connected to a lead screw rotated by a motor, and the rotation of the motor 1s converted into the movement in a linear direction o~ the lead screw.
For example, as shown in Fig. 4, a casé 20a for the automatic micrometer head is interiorly provided with a linear slide head 20b, a lead screw 20c, a gear head 20d of h~gh resolving power, and a supersmall DC motor 20e, said supersmall DC motor 20e being controlled by the main control section 10.
The linear slide head 20b has a rod-like portion 20 ~ .
at one end thereof which proJects from ~he case 20a and a cylindrical portion 20g at the other end thereof which is internally formed with internal threads 20h. The lead screw 20c is in the form of a rod, which is inserted into a cylindrical portion 20g of the linear slide head 20b and -formed in its peripheral surface with external threads 20i meshed with the external threads 20h.
The gcar head 20d oY high resolving power performs the torque conversion of the DC motor 20e with a combination of gears not shown. The main control section 10 controls the rotational amount and rotational speed of the DC motor 20e.
More specifically, as shown in Fig. 5, the main control section 10 comprises a target value setting means 21 for setting a reference ce~ter wavelength of a narrower band spectrum, a deviation detection means 22 for detecting a deviation of the measured center wavelength detected by the wavelength measuring section 8 to the reference center wavelength set by the target value setting means 21, and control means 23 for sending a signal for controlling the rotatlonal amount and rotational speed of the DC motor to the automatic micrometer head in a direction of negating the deviation detected by the deviation detection means 22.
As previously mentioned. the automatic micrometer head is composed of the automatic micrometer heads 14a and 14d for finely ad~usting the lateral deviation and the automatic micrometer heads 14b and 14c for finely adjusting '~,.
-17- ~
, , ., . ~ :: :
. : .~ : . ,:: ... .
2 ~ 3 ~ `
the angle o-~ inclination. The fine adJustment of the angle of inclination comprises an important element for the stabilizing control o~ the wavelength. The use of the a~oresaid automatic micrometer heads enables the highly ~;
accurate fine ad~ustment of the angle of inclination, say, 0.04 mrad/sec.
Next, the concrete stabilizing control of the wavelength using the present device will be described.
In the stabilizing control of the wavelength according to the present embodiment, first, the target value setting means 21 determines a reference center wavelength of a narrower spectrum as a target. In the case where the measured center wavelength detected by the wavelength measuring section 8 is deviated ~rom the aforesaid reference center wavelength, the deviation detection means 22 detects the deviation, and it is controlled so that the deviation is overcome by a control signal (a feedback signal) -from the control means 23 of the main control section 10.
That is, as shown in Fig. 3, a reference center wavelength lo as desired of the laser light ls determined ;~
while monitoring the wavelength measuring section 8, and ~ ;
under this condition, the DC motor driver 11 is locked to ~`~
temporarily fix both the etalons 3 and 4.
Next, the laser light irradiated from a laser resonator 9 is measured with the lapse o~ time by the wavelength measuring section 8. When the measured center wavelength is ~..
-- 2 ~ 3 ~
,.
deviated by ~ l from the reference center wave:length, the main control section 10 outputs a control signal for finely ad~usting the position on the light path to the etalons 3 and 4 to the DC motor driver 11. That is, out of four automatic micrometer heads 14a to 14d, the automatic micrometer head 14d for controlling an angle of inclination of the finely ad~usting etalon 4 is principally driven to finely adJust the angle of inclination.
At this time, the DC motor within the automatic micrometer head 14d is rotated through a predetermined amount -clockwise or counterclockwise depending on the fact that said deviation of ~ A is on the short wavelength side (- direction) or on the long wavelength side (+ direction).
Control parameters in the main control section 10, for example, such as the rotational direction, driving speed and driving time of the DC motor are registered in advance in a predetermined address of a memory area of the main control section 10.
The stabilizing experiment for the center wavelength by the aforementloned apparatus was conducted using one dimensional photodiode array in the procedure in which the -apparatus is operated for one hour at 80 Hz to measure the state of variation of the measured center wavelength. As the result, the wavelength stability whose variation width of the center wavelength is + 0.57 pm.
An automatic micrometer head with an encoder for . ' ' ' '' ' ' ' ,. ~ ' '' '". ' ' :. : ~
, 20S~3~
detecting the rotational amount of the motor may be used.
In this automatic micrometer head, an encoder is arranged between a spindle and a gear head so as not to count lost motion (unnecessary movement) or backlash (reverse rotation). ~ `
An example o~ a second invention, which is intended to improve the reliability of measurement in the detection of laser oscillation output, will be described below.
In Fig. 7, a laser light 103 emitted from an outlet 102 o~ a laser resonator 101 having a laser medium is partly branched by a beam splitter 104, and the branched light enters a light receiving section 105. The laser light 103 is guided to a light release section 107 at a position of a predetermined distance ~ via an optical fiber 106 connected to the light receiving section 105.
Pre~erably, the predetermined distance ~ is determined by, for example, the outpu1; standard of the laser medium 2 itself.
A photodiode as a photoelectric conversion element 110 is arranged at a position opposed to the light release ~;
section 107 through an ND ~ilter 108. At the photodiode, an output voltage is varied according to the light intensity ~rom the light release section 107.
In a drive and detection section 111, a voltage signal from the photodlode is sub~ecSed to signal processing ~ -such as A/D conversion and outputted to a control section , .
112.
~: , : r_ The control section 112 is composed of a micro-processor, a memory, etc. so that predetermined arithmetic processing is carried out according to a measured signal from the drive and detection section 111 to produce a control signal for a laser resonator 101. This control signal is delivered to the laser resonator 101 or a laser control meehanism not shown through a control line 113 to eontrol the intensity of the laser light emitted from the laser resonator 101 .
As the method for produeing a eontrol signal, there ean be mentioned a method which eomprises storing in a memory ideal control parameters obtained by sampling ln advance to be paired with the light intensity, and sequentially changing said eontrol parameters in response to the signal from the drive and deteetion seetion 111.
In the present embodiment, the distance between the laser resonator 101 and the photoeleetrie eonversion element 110 ean be sufficiently secured by the optieal fiber 106, and therefore, the photoelectrie conversion element 110 ean be arranged in the proximity of the drive and detection section 111. Thus, the in~luence of the electromagnetic noise generated in the laser resonator 101 can be minimized.
Moreover, an electric wiring 114 from the photoelectric conversion element 110 to the drive and detection section 111 ean be eonsiderably shortened.
As the result, a level of the noise signal mixed into 2~13~
..
the output signal of the photoelectric conversion element 110 can be lowered to detect a signal not impeded by the noise, and a precise control signal can be produced in the control section 112.
According to the present invention, the signal not impeded by the noise can be detected with the result that a stabilized laser output can be obtained by the control of $he laser device.
A third invention will be described hereinbelow.
As shown in Fig. 8, a laser light 203 emitted from an outlet 202 of a laser resonator 201 having a laser medium is partly branched by a beam splitter 204, and the branched light enters a light receiving element 205. A pulse detection signal sub~ected to photoelectr~c conversion by the light receiving element 205 is converted into a digital signal by an A/D conversion section 207 and enters a control section 208 after the pulse detection signal is sub~ected to ad~ustment of wavelength by an integrating circuit 206. The control section 208 is composedr for example, of a CPU
provided with arithmetic means, a register, etc., and an external memor~ device such as a memory, so that predetermined arithmetlc processing has been executed on the basis of a pulse detection signal, after which a control signal with respect to the laser resonator 201 is produced.
This control signal is outputted to the laser resonator 201 or a laser control mechanism not shown through a control ::~
~ 20~9134 line 2]0 to control the intensitY of the laser light emitted from the laser resonator 201.
The eonerete strueture of the integrating circuit 206 which eonstitutes a feature of the present embodiment will be deseribed hereinafter.
The integrating cireuit 206 is eomposed principally of four OP amplifiers 211a, 211b, 211c and 211d as shown in Fig.
10, among which the first OP amplifier 211a has a function as an amplification stage whose amplification degree is varied by seleeting a resistance value between (-) input and earth.
A pulse detection signal is integrated by th~ second to fourth OP amplifiers 211b, 211c and 211d.-In the second and third OP amplifiers 211b and 211cin Fig. 10, an input terminal is in an imaglnary short state, and condensers of 150 pF are charged to an input voltage and initial values are applied to the respective integrators to e~eet ealeulation.
As the above-deseribed OP amplifiers, those having a band width of 8.0 MHz and having a responsiveness whose through rate is about 25 V/~ s can be used.
The integrating eireuit 206 ls eonstituted by the multi-stage integrator as described above to thereby provlde a signal shown in Flg. 9(b) obtained by extending rise/attenuation time of a detection pulse signal of the order of scores o~ ns as shown in Fig. 9(a) to the order o~
seores of ~ s. Aecordingly, a pulse deteetion signal -~3-2~59~3~
corresponding to the responsive speed to the A/D conversion section 7 can be obtained to enable accurate detection of light intensity.
According to the present embodiment, since four OP
amplifiers are used to constitute the integating circuit 206, the integration of the pulse detection signal can be made without degrading the temperature characteristics of the integrating circuit 206 even in use for long periods.
According to the present invention, paying attention to the fact that the output waveform of the light receiving element represents the time distribution of light intensity, this value is integrated with respect to time to detect the light intensity as light quantities, and therefore, accurate detection of light intensity can be made.
An embodiment o~ a fourth invention will be described hereinafter with reference to Figs. 11 and 12.
A gas laser chamber 310 is interiorly provided with a discharge electrode 311. A gas control device 321 is connected to the gas laser chamber 310 through a pipe 320, and a gas cylinder 323 is connected to the gas control device 321 through a pipe 322. Thereby, a mixed gas composed of the aforementioned components is filled into the gas laser ~;
chamber 310. A high voltage generator 301 is connected to the discharge electrode 311 through a high voltage cord 312, and a third shield 313 is provided around the high voltage cord 312. The voltage o~ the high voltage generator 301 is -2~-2 ~ 3 ~
controlled by a computer 302. The high voltage generator 301 is connected to a power source 303 through a first power source line 304, and a ~irst shield 305 is provided on the first power source line 304. An insulating trans~ormer as a noise filter 306 is provided halfway o~
the first power source line 304.
Furthermore, a second shield 308 is provided on second power source line 7 for connecting the power source 3 and a computer 302.
A control line between the high voltage generator 301 and the computer 302 is comprised of an optical cable 9. An interface between the optical cable 309 and the computer 302 is as shown in Fig. 2, in which the optical cable 309 is first inputted into an optical MODEM 302a and connected to an MPU 302c through an input and output circuit 302b. RAM 302d and ROM 302e are connected to the MPU 302c.
The MPU 302c is shielded by a single Imember.
A valve actuator (not shown) within the gas control device 321 is also controlled by the computer 302, and a control line 324 also is comprised of an optical cable. A
shield 326 is applied also to a power source line 325 for connecting the gas control device 321 and the power source 303. ; -The gas laser chamber 310. high voltage generator 301, computer 302, noise filter 306 and gas control device 321 are encased in a casing (K), said casing K and said ' 9 1 ~ ~ ~
:
shields being grounded at GND.
With the structure as described above, a noise in a power source line system and a noise in a radiation system can be suppressed and prevented. That is, the noise in the power source line system enters the power source 303 with a reflective voltage wave generated in the discharge electrode 311 passing through the high voltage generator 301, from which power source the noise leaks toward various parts but the reflected component is absorbed by the noise filter 306 and does not reach the power source 303. The noise in the radiation system does not reach the power source line due to the provision o-~ the shields.
As describe~ above, the stability and reliability of operation can be secured.
According to the present invention, the shield is applied to the power source line to be a noise source and the noise filter is provided on the high voltage power source line. Therefore, noises which leak into the external portion of the casing and into the power source can be considerably suppressed.
Furthermore, since the high voltage generator and the computer for controlling the same are connected by the optical chble, the isolation therebetween is improved, and the abnormal operation of the computer can be prevented.
A ~ifth invention will be described hereinafter.
- Fi~. 13 is a structural view of a laser gas supply ~ .
' 2i~5913~
and exhaust device according to an embodiment of the present t invention. In this figure, an examp:Le of a device in connection with an excimer laser is illustrated for an explanation.
In Fig. 13, a laser chamber 401 is connected to a gas source 402 by a main pipe 403, and buffer gas, rare gas and halogen gas etc. can be supplied into the laser chamber 401.
Valves 404a to 404c driven by ~luid pressure are provided halfway of the main pipe 403 for supplying the gases so as to adjust the mixing ratio of the gases. An exhaust pipe 406 connected to a vacuum 405 is branched from the main pipe 403, and a valve 404d driven by fluid pressure ls provided halfway of the exhaust pipe 406 The aforesaid valves 404a to 404d driven by fluid pressure are driven by the pressure of a fluld such as air to open and close~the main pipe 403 and the exhaust pipe 406. The valves are designed so that a linear motion caused by increase or decrease of air pressure 1s converted into a rotational motion o~ the valve by, Eor example, an actuator or the ~ike.
Control pipes 407a to 407d for supplying air pressure are connected to the valves 404a to 404d, respectively, said control pipes 407a to 407d being moved by a predetermined distance L and connected to an electromagnetic unit 8 for controlling a supply of air.
A branched pipe 410 is extended in the midst of the main pipe 403 from the valves 404a to 404d to the laser .:
` 2~c~ 3~
chamber 401. The branched pipe 410 is moved by a predetermined distance L and connected to a pressure detector 411. The pressure detector 411 can detect the state of pressure within the main pipe 403, that is, within the laser chamber 401.
The vacuum pump 405, the electromagnetic valve unit 408 and the pressure detector 411 are connected to the control section 412 so that their operation is controlled. .
The control section 412 is composed of a microprocessor provided with, for example, a memory or the like, in which the electromagnetic unit 408 is controlled on the basis of the detected value of the pressure detector 411 to adjust the opening and closing degree of the valves 404a.to 404d so as to control the state of pressure within the laser chamber 401.
As described above, according to the present .
embodiment, the valve mechanism for opening and closing the main pipe 403 ls of the fluid pressure drive and the pressure detector 411 is connected to the branched pipe 410 which is ;
branched and moved by from the main pipe 403 whereby the .
control system for the vacuum pump 405, the electromagnetic valve unit 408, the pressure detector 411 and the like can be parted from the laser chamber 401, and all the ele:ctric wirings can be executed at a position away -from the laser chamber 401. Therefore, the control of gas supply and `~
exhaust can be made without being affected by the :.
electromagnetic noise generated in the laser chamber 401.
:.
-28- . :
. , . .. . ~ , -` 2~13~ :
Preferably, the distance L parted from the e~haust pipe 406, the control pipes 407a to 407d and the branched pipe 410 is the distance as short as possible as needed to such a degree that the vacuum pump 405, the electromagnetic valve unit 408 and the pressure detector 411 are not affected by the electromagnetic noise from the laser chamber 401.
That is, when the distance is long, lowering of detection accuracy, lowering of drive response or the like possibly occur.
According to the present invention, the lnfluence of the electromagnetic noise in the gas laser can be reduced to prevent malfunction of the gas supply and exhaust system.
An embodiment of a sixth invention will be described hereinbelow w1th reference to a block dia~ram shown in Fig.
14 showing the structure of a gas laser control device.
In Fig. 14, reference numeral 501 designates CPU o~
16 bit system or 32 bit system. A high speed processing system such as an output wavelength monitor device 509, a laser high voltage power source 510, etc. and a low speed processing system such as a gas processing system 511 are controlled according to the command ~rom the CPU 501. j, , An output signal from the CPU 501 is outputted to a high speed timer counter 502 and a low speed timer counter ~-503. These timer counters 502 and 503 independently count clock signals CL from the CPU 501 to produce a predetermined high speed clock signal and low speed clock signal.
~':
` 2~13~
A wavelength monitor control signal and a voltage settlng eontrol signal out of outputs o-f the high speed timer counter 502 are converted into digital optical signals via D/A eonverters 504 and 505 and photoelectric converters 507a and 507b, and the digital optieal signals are again eonverted into digital electric signals v~a optical fiber cables 508a and 608b and photoeleetrie eonverters 507a and 507b to eontrol the output wavelength monitor deviee 509 and the laser output high voltage power souree 510. The eontrol timing therefor is given by a timing trigger signal whieh is produeed by a parallel TTL output deviee 508a on the basis of a high speed eloek signal from the high speed timer eounter 502 and passing through the photoeleetric eonverter 507e, the optieal fiber eable 508e and the photoelectric converter 507c in named order.
On the other hand, an output from the low speed timer counter 503 is converted into a digital optical signal via a parallel TTL output deviee 506b and a photoeleetric converter 507d and is again converted into a digital electric signal via an optieal fiber eable 508d and a photoelectric converter 507d and thenee delivered to a gas proeessing system 511 ineluding a laser ehamber. The gas proeessing system 511 executes the gas replaeing wor~ or the like with a gas valve opening and elosing signal or a vaeuum pump ON/OFF signal.
As described above, in the present embodiment, a time reference of monitor eontrol of an output waveform and ,, . ., ~
.. ~, . : :. . : :
`"` 2 ~ 3 ~
laser output control requiring high speed arithmetic processing is produced by the high speed processing timer counter 502, whereas a time re~erence of gas replacing control or the like requiring low speed arithmetic processing is produced by the low speed processing timer counter 503.
As described above, two kinds of time references whlch are greatly different from each other are independently counted by the individual timer counters to enable realization of a plurality of parallel controls without stopping any of controls. -Moreover, according to the present embodiment, there is an effect in that the control slgnal is made to pass through the optical fiber cables 508a to 508d whereby the influence of the electromagnetic noises generated *rom the laser chamber or other driving systems can be reduced to prevent malfunction of the control system.
According to the present invention, the control on the basis of a plurality of time references can be made by a single control device.
INDUSTRIAL APPLICABILITY
According to the present invention, the fine ad~ustment of the wavelength selection element can be made with high accuracy, and as a result, the output waveform in the laser resonator can be greatly stabilized.
Accordingly, the present invention can be effectively utilized for uses such as a light source in a lithography ' 3 ~
step ln the manufacture of a semiconductor.
.
;~ :- :-.
~ .~
.
:
.
.. . . . , ::
.: . . . . : .: . . , . ~ :
Claims
(1) A laser device having at least first and second wavelength selection elements arranged in series on a light path, at least one angle of inclination being adjusted to form a laser light from a laser medium into a narrower band, said laser device comprising an automatic micrometer head for finely adjusting said angle of inclination.
(2) The laser device according to Claim 1, wherein said first wavelength selection element is for rough adjustment, and said second wavelength selection element is for fine adjustment.
(3) The laser device according to Claim 1 or 2, wherein said waveform selection element comprises an etalon.
(4) The laser device according to Claim 1, wherein said wavelength selection element is held in its peripheral portion by a holder, and a pair of said automatic micrometer heads is provided on said holder with the wavelength selection element sandwiched therebetween.
(5) The laser device according to Claim 1, wherein the automatic micrometer head has an encoder for detecting a rotational amount of a motor.
(6) The laser device according to Claim 1, wherein said laser device comprises a wavelength measuring section for an output laser light and a main control section for controlling said automatic micrometer heads on the basis of the wavelength of the laser light obtained from said wavelength measuring section, said main control section comprising target value setting means for setting a reference center wavelength of a narrower band spectrum as an object, deviation detection means for detecting a deviation of the measured center wavelength detected by said wavelength measuring section to the reference center wavelength set by said target value setting means. and control means for delivering a control signal to said automatic micrometer head in a direction of negating the deviation detected by said deviation detection means.
(7) A laser oscillation output detection device for measuring the light energy of a laser light emitted from a laser resonator, comprising:
a light receiving section arranged in the neighbourhood of the laser resonator;
an optical fiber having one end connected to said light receiving section to transmit a detected light from the laser resonator:
a light release section connected to the other end of said optical fiber;
a photoelectric conversion element arranged opposedly of said light release potion; and a main control section for calculating an oscillation output of said laser light on the basis of the detected signal from the photoelectric conversion element to generate a control signal to said laser resonator.
(8) A laser oscillation output detection device comprising a light receiving element for receiving a laser light, an A/D conversion section for converting a detected electric signal subjected to photoelectric conversion by the light receiving element into a digital signal, and an arithmetic means for analyzing a signal from the A/D
conversion section to calculate a laser oscillation output, wherein an integrating circuit provided with at least a multistage integrator is interposed between said light receiving element and said A/D conversion section.
(9) A laser device comprising a high voltage generator for supplying a high voltage to a discharge electrode within a gas laser chamber, and a computer for controlling said high voltage generator, characterized in that a first shield is provided on a first power source line for connecting the high voltage generator to a power source, said first power source line being provided with a noise filter halfway thereof, a second shield is provided on a second power source line for connecting the power source to a computer, a third shield is provided on a high voltage cord between said high voltage generator and said discharge electrode, and a control line for connecting said high voltage generator to said computer comprises an optical cable.
(10) A laser gas supply and exhaust device for supplying and evacuating a laser gas within a laser chamber, comprising:
a main pipe connected between a gas source and the laser chamber to introduce the laser gas of said gas source into the chamber;
a valve driven by fluid pressure provided on said main pipe and driven by fluid pressure through a control pipe from a remote position to control opening and closing the main pipe;
an electromagnetic valve device connected to the end of said control pipe;
a pressure detector connected to the end of a branched pipe from said main pipe; and a control section connected to said electromagnetic valve device and said pressure detector by electric wiring to electrically control them;
wherein the distance between said control pipe and said branched pipe is to have a sufficient length whereby said electric wiring is not affected by an electromagnetic noise generated in the laser chamber.
(11) A gas laser control device comprising at least a high speed processing system requiring a high speed processing and a low speed processing system requiring a low speed processing, wherein processing timings are independently determined by a high speed timer counter for producing a reference clock for said high speed processing and a low speed timer counter for producing a reference clock for said low speed processing, respectively.
(12) A gas laser control device according to Claim 11, wherein control items in said high speed processing system include at least an output of a discharge start signal, outputs of detection of a laser output and an output of stabilizing control signal thereof, and outputs of detection of a laser waveform and an output of stabilizing control signal thereof, whereas control items in said low speed processing system include at least an output of an opening and closing control signal of a gas valve in exchange of gas.
(2) The laser device according to Claim 1, wherein said first wavelength selection element is for rough adjustment, and said second wavelength selection element is for fine adjustment.
(3) The laser device according to Claim 1 or 2, wherein said waveform selection element comprises an etalon.
(4) The laser device according to Claim 1, wherein said wavelength selection element is held in its peripheral portion by a holder, and a pair of said automatic micrometer heads is provided on said holder with the wavelength selection element sandwiched therebetween.
(5) The laser device according to Claim 1, wherein the automatic micrometer head has an encoder for detecting a rotational amount of a motor.
(6) The laser device according to Claim 1, wherein said laser device comprises a wavelength measuring section for an output laser light and a main control section for controlling said automatic micrometer heads on the basis of the wavelength of the laser light obtained from said wavelength measuring section, said main control section comprising target value setting means for setting a reference center wavelength of a narrower band spectrum as an object, deviation detection means for detecting a deviation of the measured center wavelength detected by said wavelength measuring section to the reference center wavelength set by said target value setting means. and control means for delivering a control signal to said automatic micrometer head in a direction of negating the deviation detected by said deviation detection means.
(7) A laser oscillation output detection device for measuring the light energy of a laser light emitted from a laser resonator, comprising:
a light receiving section arranged in the neighbourhood of the laser resonator;
an optical fiber having one end connected to said light receiving section to transmit a detected light from the laser resonator:
a light release section connected to the other end of said optical fiber;
a photoelectric conversion element arranged opposedly of said light release potion; and a main control section for calculating an oscillation output of said laser light on the basis of the detected signal from the photoelectric conversion element to generate a control signal to said laser resonator.
(8) A laser oscillation output detection device comprising a light receiving element for receiving a laser light, an A/D conversion section for converting a detected electric signal subjected to photoelectric conversion by the light receiving element into a digital signal, and an arithmetic means for analyzing a signal from the A/D
conversion section to calculate a laser oscillation output, wherein an integrating circuit provided with at least a multistage integrator is interposed between said light receiving element and said A/D conversion section.
(9) A laser device comprising a high voltage generator for supplying a high voltage to a discharge electrode within a gas laser chamber, and a computer for controlling said high voltage generator, characterized in that a first shield is provided on a first power source line for connecting the high voltage generator to a power source, said first power source line being provided with a noise filter halfway thereof, a second shield is provided on a second power source line for connecting the power source to a computer, a third shield is provided on a high voltage cord between said high voltage generator and said discharge electrode, and a control line for connecting said high voltage generator to said computer comprises an optical cable.
(10) A laser gas supply and exhaust device for supplying and evacuating a laser gas within a laser chamber, comprising:
a main pipe connected between a gas source and the laser chamber to introduce the laser gas of said gas source into the chamber;
a valve driven by fluid pressure provided on said main pipe and driven by fluid pressure through a control pipe from a remote position to control opening and closing the main pipe;
an electromagnetic valve device connected to the end of said control pipe;
a pressure detector connected to the end of a branched pipe from said main pipe; and a control section connected to said electromagnetic valve device and said pressure detector by electric wiring to electrically control them;
wherein the distance between said control pipe and said branched pipe is to have a sufficient length whereby said electric wiring is not affected by an electromagnetic noise generated in the laser chamber.
(11) A gas laser control device comprising at least a high speed processing system requiring a high speed processing and a low speed processing system requiring a low speed processing, wherein processing timings are independently determined by a high speed timer counter for producing a reference clock for said high speed processing and a low speed timer counter for producing a reference clock for said low speed processing, respectively.
(12) A gas laser control device according to Claim 11, wherein control items in said high speed processing system include at least an output of a discharge start signal, outputs of detection of a laser output and an output of stabilizing control signal thereof, and outputs of detection of a laser waveform and an output of stabilizing control signal thereof, whereas control items in said low speed processing system include at least an output of an opening and closing control signal of a gas valve in exchange of gas.
Applications Claiming Priority (12)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2-99847 | 1990-04-16 | ||
| JP9984790 | 1990-04-16 | ||
| JP14344690A JPH0437178A (en) | 1990-06-01 | 1990-06-01 | Laser device |
| JP2-143446 | 1990-06-01 | ||
| JP14601290A JPH0438886A (en) | 1990-06-04 | 1990-06-04 | Controller for gas laser |
| JP2-146012 | 1990-06-04 | ||
| JP14601390A JPH0438887A (en) | 1990-06-04 | 1990-06-04 | Gas supply and exhaust device for laser |
| JP2-146011 | 1990-06-04 | ||
| JP14601190A JPH0438884A (en) | 1990-06-04 | 1990-06-04 | Detector for laser oscillation output |
| JP2-146013 | 1990-06-04 | ||
| JP19215790A JPH0477631A (en) | 1990-07-20 | 1990-07-20 | Apparatus for detecting laser oscillation output |
| JP2-192157 | 1990-07-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2059134A1 true CA2059134A1 (en) | 1991-10-17 |
Family
ID=27552084
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2059134 Abandoned CA2059134A1 (en) | 1990-04-16 | 1991-04-16 | Laser device |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2059134A1 (en) |
| WO (1) | WO1991016745A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017158231A1 (en) * | 2016-03-15 | 2017-09-21 | Teknologian Tutkimuskeskus Vtt Oy | Hyperspectral imaging arrangement |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110224757A (en) * | 2019-05-13 | 2019-09-10 | 大族激光科技产业集团股份有限公司 | A kind of laser control system and control method of electromagnetism interference |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60175475A (en) * | 1984-02-22 | 1985-09-09 | Mitsubishi Electric Corp | Automatic aligning device of laser oscillator |
| JPS62162379A (en) * | 1986-01-11 | 1987-07-18 | Nippon Kogaku Kk <Nikon> | Pulse laser |
| JPH069270B2 (en) * | 1986-05-30 | 1994-02-02 | 日本電気株式会社 | Noble gas halide excimer laser device |
| JPS6396976A (en) * | 1986-10-14 | 1988-04-27 | Fanuc Ltd | High-frequency discharge-pumped laser |
| JPS63235084A (en) * | 1987-03-20 | 1988-09-30 | Fanuc Ltd | Laser oscillation control device |
| JPS63273580A (en) * | 1987-04-30 | 1988-11-10 | Fanuc Ltd | Power control system for cnc laser beam machine |
| JP2723516B2 (en) * | 1987-04-30 | 1998-03-09 | ファナック 株式会社 | Laser oscillation device |
| JPS63273378A (en) * | 1987-04-30 | 1988-11-10 | Fanuc Ltd | Laser oscillator |
| JP2804027B2 (en) * | 1987-07-13 | 1998-09-24 | ファナック 株式会社 | Laser output correction method |
| JP2649357B2 (en) * | 1987-08-25 | 1997-09-03 | 株式会社小松製作所 | Excimer laser wavelength controller |
| JPH0779177B2 (en) * | 1987-12-24 | 1995-08-23 | 株式会社東芝 | Laser controller |
| JPH01184887A (en) * | 1988-01-13 | 1989-07-24 | Toshiba Corp | Pulse laser oscillator |
| JP2699081B2 (en) * | 1988-03-31 | 1998-01-19 | 株式会社小松製作所 | Laser wavelength control method |
| JP2657532B2 (en) * | 1988-09-30 | 1997-09-24 | 株式会社小松製作所 | Narrow-band oscillation excimer laser device |
-
1991
- 1991-04-16 WO PCT/JP1991/000495 patent/WO1991016745A1/en not_active Application Discontinuation
- 1991-04-16 CA CA 2059134 patent/CA2059134A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017158231A1 (en) * | 2016-03-15 | 2017-09-21 | Teknologian Tutkimuskeskus Vtt Oy | Hyperspectral imaging arrangement |
| US9835847B2 (en) | 2016-03-15 | 2017-12-05 | Teknologian Tutkimuskeskus Vtt Oy | Hyperspectral imaging arrangement |
Also Published As
| Publication number | Publication date |
|---|---|
| WO1991016745A1 (en) | 1991-10-31 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR100907299B1 (en) | Very narrow band, two chamber, high rep rate gas discharge laser system | |
| US6272158B1 (en) | Method and apparatus for wavelength calibration | |
| US5978394A (en) | Wavelength system for an excimer laser | |
| US7106763B2 (en) | Wavelength control for cavity ringdown spectrometer | |
| EP0992093B1 (en) | Wavelength system for an excimer laser | |
| JP2008294477A (en) | Super narrow band, two-chamber, high repetition rate gas discharge laser system | |
| Snyder et al. | Determination of gas-temperature and velocity profiles in an argon thermal-plasma jet by laser-light scattering | |
| US6529533B1 (en) | Beam parameter monitoring unit for a molecular fluorine (F2) laser | |
| WO2001026191A1 (en) | Bandwidth estimating technique for narrow band laser | |
| US6636297B2 (en) | Vacuum ultraviolet laser wavelength measuring apparatus | |
| US6735232B2 (en) | Laser with versatile output energy | |
| JP4393457B2 (en) | Control system for two-chamber discharge gas laser | |
| Schäfer et al. | Saturated 2D-LIF of OH and 2D determination of effective collisional lifetimes in atmospheric pressure flames | |
| US6907058B2 (en) | Energy monitor for molecular fluorine laser | |
| CA2059134A1 (en) | Laser device | |
| CN111404030B (en) | Novel Faraday anomalous dispersion Rb atom filter and method | |
| JP2000106463A (en) | Wavelength calibration method and system for excimer laser | |
| CN113418626A (en) | Device and method for measuring zero expansion temperature point of Fabry-Perot cavity | |
| Bolotin et al. | Status of the Novosibirsk free electron laser and first experiments with high power terahertz radiation | |
| Kwater | Laser calibration of the Mössbauer spectrometer velocity: Improvements in design | |
| Knittel et al. | A plasma shutter for far-infrared laser radiation | |
| DeSilva | Spectral analyzer for Thomson scattering | |
| RU1307995C (en) | Method of intraresonator laser spectroscopy | |
| Srivastava et al. | A sub-Doppler resolution double resonance molecular beam infrared spectrometer operating at chemically relevant energies (∼ 2 eV) | |
| Hutchinson et al. | All-weather long-wavelength infrared free-space optical communications |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |