JP4540243B2 - Pulse laser power supply - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pulse laser power source combining a pulse generation circuit and a waveform shaping circuit, and more particularly to a cooling structure using a refrigerant.
[0002]
[Prior art]
In recent years, a pulse laser apparatus typified by an excimer laser is used for an exposure apparatus for manufacturing a semiconductor or a light source for surface processing of an object, and industrial demand is increasing. In order to excite the pulse laser, it is necessary to discharge by applying a voltage of an ultrashort pulse of microsecond or less to the laser device. In order to generate such an ultrashort pulse voltage, an initial charge was performed. A waveform shaping circuit is used that generates an initial pulse by turning on a semiconductor switch from a capacitor, charges a capacitor in the next stage, and further compresses the pulse width using the saturation characteristics of the saturable reactor. A circuit of this type of pulsed laser power supply is shown in FIG.
[0003]
In FIG. 2, the pulse generating circuit 2 is connected to the high-voltage DC power source 1 and the initial stage charge / discharge capacitor Co is initially charged, and the on / off control of the semiconductor switch SW changes the charge / discharge capacitor Co to the waveform shaping circuit 3. Transmit pulse voltage. Transmitted pulse is boosted via the magnetic assist saturable reactor Lo in the pulse transformer PT to a predetermined voltage, and supplies a charge to the capacitor C _1. The magnetically assisted saturable reactor Lo is provided to reduce the switching loss of the semiconductor switch SW by using magnetic saturation.
[0004]
A combination of a capacitor and a saturable reactor is often used for pulse compression in a plurality of stages. As a typical example, a two-stage waveform shaping circuit shown in FIG. 2 will be described.
In FIG. 2, when the capacitors are C ₁ and C ₂ and the saturable reactors are L ₁ and L ₂ , when charge is supplied to the capacitor C ₁ , the voltage rises and the saturable reactor L ₁ is excited, , Ie, voltage × time (V × sec), the saturable reactor L ₁ is magnetically saturated and the inductance value is drastically reduced. This makes it possible to charge the next stage of the capacitor C ₂ magnetic switch operates is moved to pulse charging. Hereinafter, the same operation is repeated even when the number of stages is large. However, since the inductance after saturation is designed to be smaller in the subsequent reactor, the charging time is shortened and pulse compression is performed.
[0005]
The last-stage capacitor C ₂ applies a very narrow pulse voltage to the pulse laser generator 4 when the saturable reactor L ₂ is saturated, so that the voltage of the gap between the laser electrodes of the pulse laser generator 4 rises rapidly. insulated is broken, the charge stored in the capacitor C ₂ laser is injected into the laser catalyst is excited.
The waveform shaping circuit 3 in FIG. 2 is a pulse transformer PT is provided in parallel to the input side of the capacitor C ₁ may be provided in parallel with other capacitor C _2. In the waveform shaping circuit 3 having a larger number of stages, it is effective to provide it in parallel with an arbitrary capacitor.
[0006]
When this type of power supply is operated repeatedly, the temperature of the core component 16 of the waveform shaping circuit 3, that is, the magnetically assisted saturable reactor Lo, the pulse transformer PT, the saturable reactors L ₁ and L ₂ mainly increases. The core component 16 is housed in an oil tank 6 filled with insulating oil 5 and cooled.
[0007]
On the other hand, the temperature rise of the capacitors C ₁ and C ₂ does not increase so much because the dielectric loss is small, and the waveform shaping circuit 3 has a circuit configuration for the purpose of pulse compression. Don't be.
Therefore, the capacitors C ₁ and C ₂ are also housed in the same oil tank 6 so that the shortest wiring is possible together with the core component 16 .
[0008]
[Problems to be solved by the invention]
Now, this type of power supply is pulsed at a high repetition rate of several hundred Hz to several thousand Hz, and there is a demand from customers to perform a higher repetition operation. However, with this type of power supply, a narrow pulse voltage is repeatedly passed, so that the core component of the waveform shaping circuit increases eddy current loss (iron loss), and the winding also increases copper loss due to the skin effect. The temperature rise of parts increases. Accordingly, heat is radiated by insulating oil for refrigerant for cooling, cooling is further provided on the outer surface of the oil tank, or a heat exchanger is used for cooling.
[0009]
On the other hand, the capacitors housed in the same oil tank have a small temperature rise due to their own dielectric loss, which is not a problem. However, since they are arranged close to the core parts, the insulating oil, which is a refrigerant, is used. It rises to a temperature close to the core parts. Therefore, the capacitance of the capacitor changes due to the temperature rise. In general, a ceramic capacitor is used for this type of capacitor in consideration of pulse performance, miniaturization, and structurally low inductance. However, there is a problem that a capacitance change due to temperature is large.
[0010]
Therefore, the change in capacitance changes the pulse charging voltage of the capacitors C ₁ and C ₂ , or the saturation point of the saturable reactors L ₁ and L ₂ is changed. There have been problems such as changes in timing and unstable laser oscillation.
[0011]
The present invention has been made to solve the above-described problems, and provides a pulsed laser power source having a waveform shaping circuit having a structure in which a capacitor is hardly affected by heat from a core component as much as possible.
[0012]
[Means for Solving the Problems]
That, in combination with the pulse generating circuit 2 for generating a pulse voltage from a initial charge discharge condenser Co on-control of the semiconductor switch SW, and a core part 16 and the capacitor C _1, C _2, including a saturable reactor is configured, a waveform shaping circuit 3 for pulse compression pulse voltage, the pulse laser power and a pulse laser generator 4 for generating a laser is supplied with pulse compression pulse voltage waveform shaping circuit 3, waveform The molded circuit 3 is filled with an insulating oil 5 and is housed in an oil tank 6 closed by an upper lid 11 to which a heat exchanger 8 is attached, and the core component 16 is stacked in the center of the oil tank 6 in is arranged, the capacitor _C 1, _{C 2} is attached to the capacitor mounting plate 10, the capacitor _C 1 the capacitor mounting plate 10, _{C 2} and the core component 1 The core component 16 and the capacitor mounting plate 10 are arranged to face each other so that the insulating oil 5 heated and raised by the core component 16 is cooled by the heat exchanger 8, and the cooled and lowered insulating oil 5 is The pulse laser power source is characterized in that the insulating oil 5 convected to the capacitor side with respect to the capacitor mounting plate 10 and circulated through the core component 16 after reaching the bottom of the oil tank 6 .
[0013]
The core part 16 is a pulsed laser source, wherein the magnetic assist saturable reactor Lo, pulse transformer PT, to become a saturable reactor for pulse compression _L 1, _{L 2.}
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. FIG. 1 is an assembly sectional view showing a waveform shaping circuit of a pulse laser power source according to a comparative example of the present invention. Figure 3 is an assembled cross-sectional view of a real施例. The same circuit elements as those in FIG. 2 are denoted by the same symbols, and the description thereof is omitted.
[0016]
【Example】
[ Comparative Example]
In FIG. 1, a core part 16 composed of a magnetically assisted saturable reactor Lo, a pulse transformer PT, a saturable reactor L ₁ , and a saturable reactor L ₂ is replaced with an insulating core fixing base 7 and a core considering the withstand voltage between the respective parts. Fix using the holding table 9. However, since the core parts 16 are different in size and shape, the shapes of the core fixing base 7 and the core holding base 9 are also in accordance with them. On the other hand, the capacitors C ₁ and C ₂ are attached to the capacitor mounting plate 10 while maintaining an insulation distance considering the withstand voltage therebetween. Note that both capacitors may be separated into separate capacitor mounting plates 10 as long as the fixing method is appropriate.
[0017]
Next, the above components are assembled to the oil tank 6. In this method, the core component 16 is fixed to the center of the oil tank 6, and the capacitor mounting plate 10 having the capacitors C ₁ and C ₂ attached to its periphery is fixed. Capacitors C ₁ and C ₂ are divided into four surfaces toward the core component 16 side. Each component is wired using an electric wire according to the circuit shown in FIG. 2, and the upper lid 11 is tightened so as to be sealed using a packing (not shown). A heat exchanger 8 is attached to the back surface of the upper lid 11.
[0018]
In the cooling method, water is injected into the heat exchanger 8 from the outside, and insulating oil 5 for refrigerant is injected into the oil tank 6 from an inlet (not shown) attached to the upper lid 11. Although an input terminal and an output terminal are provided in this oil tank, the description thereof is omitted.
[0019]
Next, the operation will be described. Since the electrical operation has been described in the descriptions [0003] to [0005] according to FIG. 2, the description thereof will be omitted, and the flow of heat will be described here.
When the core component 16 disposed in the center of the oil tank 6 generates heat, it radiates heat to the refrigerant insulating oil 5, and the heated insulating oil 5 rises to the top of the oil tank 6 and eventually reaches the heat exchanger 8. Then cooled. The cooled insulating oil 5 moves to the side surface of the oil tank 6 and descends while cooling the capacitors C ₁ and C ₂ , and again absorbs heat from the core component 16 and rises. That is, convection 12 is generated. Compared to the conventional structure in which the heating element and other parts are mixed with emphasis on the wiring and shape, the heating element is placed in the center and the parts are arranged along the flow of the convection 12. Is an effective means capable of minimizing the temperature rise of the capacitors C ₁ and C ₂ . In FIG. 1, the capacitor is arranged around the oil tank 6, but it is also effective to arrange a part of the capacitor in the lower part.
[0020]
〔Example〕
Figure 3 is an assembly sectional view showing a real施例waveform shaping circuit in the pulsed laser source of the present invention. The same circuit elements as those in FIGS. 1 and 2 are denoted by the same reference numerals, and the description thereof is omitted. Example of Figure 3 is obtained by attempting to better utilize the convection of the insulating oil 5 is a refrigerant, difference from the first embodiment is attached the capacitor C ₁ to capacitor mounting plate 10, the mounting plate 10 the core located in the component side, it is arranged on the side surface of the oil tank 6 (Fig. 4, reference plane view of FIG.), using a capacitor fixed base 15 on the lower side of the bottom surface of the core part 16 of the capacitor C ₂ oil tank 6 Arranged.
[0021]
The structure will be described. The core component support base 13 is fixed to the central portion of the oil tank 6, and the core component 16 shown in FIG. 1 is fixed thereon. The capacitor mounting plate 10 is fixed to the core component support base 13 as an example. The mounting direction is a capacitor C ₁ to the side surface side of the oil tank 6, so that the capacitor mounting plate 10 comes to the core part 16 side. On the other hand, the capacitor C ₂ attached to the capacitor fixing base 15 is fixed to the bottom of the oil tank 6 by a capacitor holding base 14 arranged so as to be inserted into the lower part of the core component support base 13. The side surface of the core component support base 13 and the core fixing base 7 are partially cut out so that the insulating oil 5 can pass freely. On the other hand, the capacitor mounting plate 10 requires a hole for partially passing an electric wire due to the necessity for wiring, but the area of the hole is small, and insulation from the capacitor C ₁ , C ₂ side to the core component 16 side. The passage of oil 5 is not easy.
[0022]
Next, the flow of the insulating oil 5 will be described. The insulating oil 5 warmed by the core component 16 continues to rise and reaches the heat exchanger 8 to be cooled. Since even after the insulating oil 5 warmed come rises, cooled insulating oil 5 drops the sides of the oil tank 6 through the capacitor C ₁ reaches the bottom of the oil tank 6, further passes through the condenser C ₂ And reaches the bottom of the core part 16 . And it continues rising while taking heat of the core component 16 again. This flow is indicated by convection 12. That is, a capacitor mounting plate 10 of this flow works effectively is because the shields and a capacitor C ₁ side and the core part 16 side, by which the core component 16 is cooled, overheating of the core components It is possible to prevent the insulating oil 5 thus made from entering the capacitors C ₁ and C ₂ as they are.
[0023]
In FIG. 3, the capacitor C ₁ is disposed on the side surface of the oil tank 6 and the capacitor C ₂ is disposed on the bottom surface. The capacitor C ₂ may be mounted together on the mounting surface of the capacitor C ₁ from the relationship of the capacitor capacity, or vice versa. Further, although the waveform shaping circuit 3 is shown as an example of two stages, it is similarly effective even when the number of stages is increased. As shown in the above embodiment, the same effect can be obtained if the core component 16 is disposed in the center of the oil tank 6 and the capacitor is disposed in the periphery (including the bottom).
[0024]
Next, a capacitor mounting plate mounting structure arranged around the core component is effective depending on the external shape of the core component. If the core part is square, it is a dihedral or tetrahedral, and an example of the tetrahedral is shown in FIG. Further, if the core part is cylindrical, it is better to make it close to a circle. However, since the structure does not work well, it is generally preferable to use a tetrahedron arrangement. An example of the octahedron is shown in FIG.
4 and 5 are plan views as seen from above with the top lid 11 removed. Since the symbols are the same as those in FIG. 1, their description is omitted.
[0025]
【The invention's effect】
As described above, according to the present invention, the core component is arranged in the center of the oil tank and the capacitor is arranged in the periphery (including the bottom) so that the insulating oil convects smoothly. The effect can be kept to a minimum without affecting the other parts.
In addition, since the capacitor mounting plate is arranged on the core component side and the capacitor is arranged on the oil tank side, the cooled refrigerant, that is, the insulating oil can be guided to the bottom surface by convection. ,effective.
And since it is the structure where the overheated insulating oil does not touch a capacitor | condenser directly, there exists an advantage that the temperature rise of a capacitor | condenser can be suppressed to the minimum.
As a result, the thermal change of the capacitor capacity is reduced, and the waveform, voltage, and output time timing output from the waveform shaping circuit to the pulse laser generator are not changed, and stable laser oscillation can be performed.
Furthermore, this type of power supply has a high voltage of several kV to several tens of kV, and discharges several hundred to several thousand times per second, so that a large amount of energy is handled. Therefore, as the operation shifts to high repetition, the heat generation of the core parts increases and the countermeasures for the temperature of the peripheral parts become necessary. This greatly contributes to the improvement of reliability as a pulse laser device, and has a great industrial value.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pulse laser power source according to a comparative example of the present invention.
FIG. 2 is a circuit diagram of a general pulse laser power source.
Figure 3 is a cross-sectional view of a pulsed laser power supply by Real施例of the present invention.
Figure 4 is a plan view of a pulsed laser power supply by Real施例of the present invention.
FIG. 5 is a plan view of a pulsed laser power source according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 High voltage DC power supply 2 Pulse generation circuit 3 Waveform shaping circuit 4 Pulse laser generation part 5 Insulating oil 6 Oil tank 7 Core fixing stand 8 Heat exchanger 9 Core holding stand 10 Capacitor mounting plate 11 Upper lid 12 Convection 13 Core component support stand 14 Capacitor holding base 15 Capacitor fixing base
16 core parts Co charge / discharge capacitor SW semiconductor switch Lo magnetic assist saturable reactor PT pulse transformer C ₁ capacitor C ₂ capacitor L ₁ saturable reactor L ₂ saturable reactor

Claims (2)

A pulse generation circuit that generates a pulse voltage from an initially charged charge / discharge capacitor by on-control of a semiconductor switch;
A waveform shaping circuit configured by combining a core component including a saturable reactor and a capacitor, and pulse-compressing the pulse voltage ;
In a pulse laser power source comprising a pulse laser generator that generates a laser by receiving supply of a pulse voltage pulse-compressed by the waveform shaping circuit ,
The waveform shaping circuit is:
It is filled with insulating oil and stored in an oil tank closed with an upper lid to which a heat exchanger is attached.
The core component is arranged in a state of being laminated at the center of the oil tank,
The capacitor is mounted on a capacitor mounting plate, and the core component and the capacitor mounting plate are arranged to face each other so that the capacitor mounting plate shields the capacitor and the core component.
The insulating oil heated and raised by the core component is cooled by the heat exchanger, and the cooled and lowered insulating oil is convected to the capacitor side with respect to the capacitor mounting plate, and the insulating oil that has reached the bottom of the oil tank is A pulsed laser power supply characterized by being circulated through core components . The core component is a magnetic assist saturable reactor, pulse transformer, pulse laser source according to claim 1, characterized in that a pulse compression saturable reactor.

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