JP2005268461A - Jet nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jet nozzle that is easy for maintenance and whose maintenance cost is reduced. <P>SOLUTION: The jet nozzle is used for a light source device that produces an extreme ultraviolet light, and it discharges a target substance as a target to which a laser beam is given to produce the extreme ultraviolet light. The jet nozzle is provided with: a target discharging part 11 wherein a first passage is formed inside and a target substance supplied to one end of the first passage is discharged to the other end thereof; a supporting part 12 wherein a second passage and a cooling chamber are formed inside, the target substance supplied to one end of the second passage is cooled, and it is supplied to the target discharging part from the other end of the second passage; and fixing means 13 and 14 that fix the target discharging part onto the supporting part in attachable/detachable manner so that the first and second passages can be communicated. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is a jet nozzle used in a light source device that generates extreme ultra violet (EUV) light, and emits a target material to be irradiated with a laser beam in order to generate EUV light. It relates to a jet nozzle.

  With the miniaturization of semiconductor processes, the miniaturization of optical lithography is rapidly progressing, and in the next generation, fine processing of 100 to 70 nm and further fine processing of 50 nm or less are required. For example, in order to meet the demand for fine processing of 50 nm or less, development of an exposure apparatus that combines an EUV light source with a wavelength of about 13 nm and a reduced projection reflection optical system (cataoptric system) is expected.

  As the EUV light source, an LPP (laser produced plasma) light source using plasma generated by irradiating a target with a laser beam, a DPP (discharge produced plasma) light source using plasma generated by discharge, and orbital radiation light There are three types of SR (synchrotron radiation) light sources used. Among these, since the LPP light source can considerably increase the plasma density, extremely high brightness close to that of black body radiation can be obtained, and light emission only in a necessary wavelength band is possible by selecting a target material, which is almost isotropic. Because it is a point light source with a typical angular distribution, there is no structure such as an electrode around the light source, and it is possible to secure a very large collection solid angle of 2πsterad. It is considered to be a powerful light source for required EUV lithography.

  FIG. 7 shows a configuration of a conventional light source device. The nozzle 101 cools a target substance (hereinafter referred to as “target substance”) supplied from the target supply apparatus 102 using the refrigerant supplied from the refrigerant supply apparatus 103 and then injects it downward. Plasma 106 is generated by irradiating the target with a laser beam formed by converging the laser light generated from the driving laser 104 with the condenser lens 105. The EUV light emitted from the plasma 106 is condensed by a condensing mirror 107 and is transmitted as a light beam (for example, parallel light) 108 to an exposure machine.

  In general, the flow path of a jet nozzle for target injection used in an EUV light source is directed from the upper part to the lower part in order to stably supply the target material to the laser beam irradiation region. In order to increase the density of the target material, it is desirable to supply a liquid or solid target material to the laser beam irradiation region.

  FIG. 8 is a cross-sectional view of a conventional jet nozzle. As shown in FIG. 8, the conventional nozzle 101 has a nozzle tip portion 110, a flow path portion 111, and a cooling chamber 112. The target material is supplied from the target supply device 102 shown in FIG. 7 in the pressurized gas state to the inside of the flow path unit 111 and is liquefied in the cooling chamber 112. The liquefied target material is fed into a flow path formed in the nozzle tip 110 and is ejected from the discharge port. Here, the inner diameter of the flow path of the nozzle tip 110 is smaller than the inner diameter of the flow path 111.

  As described above, the conventional jet nozzle is an expensive part because the nozzle tip and the cooling chamber are integrally formed, and the inner diameter of the flow path at the nozzle tip is as high as 10 μm to 100 μm. If a thin and highly precise process is performed with respect to roundness, inner surface smoothness, etc., the flow path at the nozzle tip can be formed only to a depth of about 0.1 mm to 1 mm, which is 10 times the inner diameter of the flow path. Therefore, it is difficult to process a large jet nozzle in which the nozzle tip and the cooling chamber are integrally formed.

  By the way, in a LPP light source, when a target material is irradiated with a laser beam in order to generate plasma, the nozzle tip is damaged by radiant heat generated when the target material in the laser beam irradiation region is turned into plasma.

  When the target material is irradiated with a laser beam, an ionized target that is generated at a high speed when the laser beam irradiation region is turned into a plasma and collides with the periphery (nozzle, etc.) of the laser beam irradiation region. For example, the target material scatters in the vicinity thereof and is released in a large amount as a particle lump (debris) having a diameter of several μm or more, and adheres to the tip of the nozzle and causes damage.

  Therefore, since it is necessary to replace the damaged jet nozzle, it is desired to facilitate maintenance. Further, since the jet nozzle in which the nozzle tip and the cooling chamber are integrally formed is an expensive part, there is a problem that maintenance is expensive.

As a related technique, the following Patent Document 1 discloses a nozzle for a laser plasma extreme ultraviolet radiation source using a target material feeding tube. In this nozzle, the feed tube is positioned to provide a gap between the feed tube and the heat exchanger and to provide a gap between the feed tube and the inner wall of the body portion in the bore. As such, the delivery tube can be thermally isolated from the heated graphite body portion. However, there is no mention of nozzle maintenance.
Japanese Patent Laying-Open No. 2003-43199 (pages 1 and 4 and FIG. 2)

  Therefore, in view of the above points, an object of the present invention is to provide a jet nozzle that can be easily maintained and can reduce the cost of maintenance.

  In order to solve the above problems, a jet nozzle according to the present invention is used in a light source device that generates extreme ultraviolet light, and emits a target material that is a target irradiated with a laser beam in order to generate extreme ultraviolet light. A target discharge portion for discharging a target material supplied to one end of the first flow path from the other end of the first flow path, wherein the first flow path is formed therein, A second flow path and a cooling chamber are formed inside, and a support for cooling the target material supplied to one end of the second flow path and supplying the target material from the other end of the second flow path to the target discharge portion And a fixing means for detachably fixing the target discharge portion to the support portion so that the first flow path and the second flow path communicate with each other.

  According to the present invention, it is possible to provide a jet nozzle that can be easily maintained by using the holder portion that detachably fixes the target discharge portion to the support portion, and can reduce maintenance costs.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a cross-sectional view of a jet nozzle according to a first embodiment of the present invention. This jet nozzle is arranged in a vacuum-evacuated chamber in an LPP (laser produced plasma) type EUV light source using plasma generated by irradiating a target with a laser beam, and liquefies a target material such as xenon. And used to discharge from the tip.

  As shown in FIG. 1, the jet nozzle 10 has a first flow path formed therein, and a target substance (hereinafter referred to as “target material”) supplied to one end of the first flow path is a first. A target discharge section 11 that discharges from the other end of the flow path, a second flow path and a cooling chamber are formed therein, and the gaseous target material supplied to one end of the second flow path is cooled and liquefied. A support unit 12 for supplying a liquid target material from the other end of the second flow path to the target discharge unit 11, a holder unit 13 for detachably fixing the target discharge unit 11 to the support unit 12, and a target discharge A leaf spring 14 sandwiched between the portion 11 and the holder portion 13 is included.

  A gasket-like seal 15 is inserted between the target discharge portion 11 and the support portion 12. The seal 15 is formed with a hollow region for communicating the flow path of the target discharge part 11 and the flow path of the support part 12.

  The holder portion 13 is a tubular body in which a hollow space that encloses the target discharge portion 11 and the support portion 12 is formed. By forming a male screw on the support portion 12 and forming a female screw corresponding to the male screw of the support portion 12 on the holder portion 13, one end of the holder portion 13 can be integrated with the support portion 12, The other end of the holder portion 13 is engaged with the leaf spring 14. With this configuration, it is possible to remove only the target discharge portion 11 that has deteriorated due to damage caused by radiant heat or the like. Therefore, maintenance can be easily performed by replacing only the target discharge portion 11, and a cooling chamber is formed. The supporting portion 12 and the like that are present can be reused, and maintenance costs can be reduced. Furthermore, since the target discharge portion 11 having a very thin inner diameter can be used as an independent component, it is easy to form a flow path for the target discharge portion 11. In addition, as a material of the holder part 13, in order to improve the efficiency of the xenon cooling control, a metal material such as copper or aluminum having a good heat conductivity and a small heat capacity is desirable.

  A gas xenon adjusted to a desired pressure by a regulator is supplied to the flow path of the support portion 12 from a gas cylinder storing high-purity xenon. Further, liquid nitrogen of minus about 196 ° C. is supplied as a refrigerant to the cooling chamber of the support portion 12. The gaseous xenon supplied to the flow path is cooled by the liquid nitrogen supplied to the cooling chamber via the heat exchanging section, and liquefies below the boiling point under pressure. For example, when the back pressure of the supplied gas xenon is 2.4 MPa, the xenon is liquefied at about minus 100 ° C.

  The xenon that has become liquid is fed into the target discharge unit 11 in a pressurized state and is ejected from the target discharge unit 11. Note that the temperature of the target material xenon is controlled by the flow rate of the refrigerant flowing in the cooling chamber.

  By the way, since the work in vacuum is difficult when the target discharge unit 11 is replaced, the jet nozzle is tightened and sealed at room temperature in the atmosphere, but when jetting the target material, the jet nozzle is cooled. When there is such a temperature difference, a gap is generated due to a difference in shrinkage rate of each component, and the target material may leak from the seal portion. Further, when the target material leaks from the seal portion, the pressure of the target material in the target discharge portion 11 is reduced, the jet injected from the target discharge portion 11 becomes unstable, and the leaked target material is vacuumed in the chamber. Will reduce the degree.

  In order to prevent this, it is conceivable that the sealing surface is brought into close contact with each other by the repulsive force of the sealing material generated by the crushing margin of the seal 15 to keep the airtightness. However, in order to obtain this repulsive force, it is necessary to increase the cross-sectional area of the seal 15 and fix the target discharge portion 11 with a large force.

  Therefore, in the present embodiment, the force necessary for keeping the seal surface in close contact and maintaining airtightness is obtained not by the repulsive force of the seal 15 but by the elastic force of the leaf spring 14. That is, by applying a pressure that presses the target discharge portion 11 against the support portion 12 due to the elasticity of the leaf spring 14, even if a temperature change occurs, the airtightness between the target discharge portion 11 and the support portion 12 is maintained. Making it possible.

  In this case, since the cross-sectional area of the seal 15 can be reduced, the force generated by the internal pressure of the seal 15 is also reduced, and it is possible to reduce the size of the mechanical component that applies pressure to press the target discharge portion 11 against the support portion 12. Become. Furthermore, it is possible to realize a small jet nozzle that can obtain a force for applying a pressure for pressing the target discharge portion 11 against the support portion 12 by manually tightening the holder portion 13 without using a tool. .

  As described above, by maintaining the airtightness between the target discharge unit 11 and the support unit 12, leakage of liquid xenon from the seal portion between the target discharge unit 11 and the support unit 12 can be prevented. . Thereby, the internal pressure of the target discharge | release part 11 can be hold | maintained and a target material can be stably supplied to a laser beam irradiation area | region. Further, by preventing leakage of the target material, it is possible to prevent EUV light energy from being absorbed by the leaked xenon and lowering the output.

  In this embodiment, Teflon (registered trademark) having a low temperature characteristic and a large thermal shrinkage is used as the sealing material, and the inner diameter of the Teflon (registered trademark) formed in a gasket shape is set at a temperature at which xenon is liquefied. The inner diameter of Teflon (registered trademark) at room temperature is made larger than the inner diameter of the inlet of the target discharger 11 so as to be equal to the inner diameter of the inlet of the discharger 11. Thereby, it is difficult to form a gas reservoir between the target discharge portion 11 and the support portion 12, and the amount of impurities remaining in the gas reservoir can be suppressed. Therefore, xenon can be stably supplied to the laser beam irradiation region.

  In FIG. 2, an example of the shape of the leaf | plate spring used in this embodiment is shown. 2A is a plan view of the leaf spring 14, and FIG. 2B is a cross-sectional view taken along the II-II plane in FIG. 2A. As a material of the leaf spring 14, stainless steel (SUS: special use stainless steel) that is less degassed even in a vacuum is used.

  As shown in FIG. 2A, the leaf spring 14 is formed with a hole through which the tip of the target discharge portion 11 penetrates in the center of the disc-shaped SUS. Also, four slits extending from the hole to the outside of the disk are formed. In this embodiment, the elastic force is generated by the deflection margin formed by the four slits. That is, as shown in FIG. 2B, the bending allowance of the leaf spring 14 is bent by a deflection amount σ within the elastic limit, thereby generating the elastic force of the force F. By changing the number and length of the slits, the shape of the deflection allowance can be changed, and the magnitude of the elastic force with respect to the deflection amount can be adjusted.

  The number and length of the slits of the leaf spring 14 depend on the amount of thermal contraction at the ultimate temperature of the target discharge portion 11, the holder portion 13, the leaf spring 14 and the seal 15 shown in FIG. 1 and the internal pressure of the target discharge portion 11. It is determined. That is, the deflection amount of the leaf spring 14 is larger than the total thermal contraction amount of each part at the ultimate temperature, and further, the total thermal contraction amount of each part at the ultimate temperature is subtracted from the deflection amount of the leaf spring 14. The remaining amount of deflection is designed to withstand the internal pressure of the target discharge portion 11.

  In the present embodiment, the support portion 12 is provided with a stopper so as to have reproducibility of the deflection amount set at the time of fixing. That is, at the time of fixing, the holder portion 13 is abutted against the stopper and fixed, so that the amount of deflection is constant. Further, by changing the position of the stopper, it is possible to cope with an arbitrary temperature and internal pressure.

Next, a modification of the first embodiment of the present invention will be described.
FIG. 3 is a cross-sectional view of a jet nozzle according to a modification of the first embodiment of the present invention. As shown in FIG. 3, the jet nozzle 20 includes a support portion 21 instead of the support portion 12 shown in FIG. About another structure, it is the same as that of the jet nozzle shown in FIG. Note that a pulse tube 22 for cooling the target material and the like is connected to the support portion 21, and the pulse tube 22 is equipped with a thermistor 23 that measures the temperature of the pulse tube 22.

  A cooling chamber for liquefying gaseous xenon and a flow path for sending gaseous xenon to the cooling chamber are formed in the support portion 21. In the cooling chamber, a heat exchange part is formed for taking energy from gaseous xenon by the pulse tube 22 and liquefying it. The jet nozzle 20 controls the operation of the pulse tube 22 based on the temperature of the pulse tube 22 measured by the thermistor 23, and circulates the cooled gaseous helium in the pulse tube 22, so that the xenon and target emission are performed. The temperature of the part 11 and the holder part 13 is controlled.

Next, a second embodiment of the present invention will be described.
FIG. 4 is a cross-sectional view of a jet nozzle according to the second embodiment of the present invention. As shown in FIG. 4, the jet nozzle 30 removes the leaf spring 14 from the jet nozzle shown in FIG. 1 and includes a holder portion 31 instead of the holder portion 13. About another structure, it is the same as that of the jet nozzle shown in FIG.

  In the present embodiment, the force necessary for keeping the seal surface in close contact and maintaining airtightness is obtained not by the repulsive force of the seal 15 but by the elastic force of the holder portion 31. That is, even if a temperature change occurs by applying a pressure that presses the target discharge portion 11 against the support portion 12 by the elasticity of the claw portion of the holder portion 31, the airtightness between the target discharge portion 11 and the support portion 12. It is possible to maintain.

  The shape of the holder portion 31 is determined by the amount of thermal contraction at the temperature reached by the target discharge portion 11, the holder portion 31 and the seal 15, and the internal pressure of the target discharge portion 11. That is, the deflection amount of the claw portion of the holder portion 31 is larger than the total amount of heat shrinkage of each portion at the ultimate temperature, and further, the heat of each portion at the ultimate temperature is determined from the deflection amount of the claw portion of the holder portion 31. It is designed to be able to withstand the internal pressure of the target discharge portion 11 by the remaining deflection amount obtained by subtracting the total contraction amount.

  In the present embodiment, the support portion 12 is provided with a stopper so as to have reproducibility of the deflection amount set at the time of fixing. That is, at the time of fixing, the holder portion 31 is abutted against and fixed to the stopper so that the amount of deflection is constant. Further, by changing the position of the stopper, it is possible to cope with an arbitrary temperature and internal pressure.

  As a material of the holder part 31, in order to improve the efficiency of cooling control of xenon, a metal material such as copper or aluminum having good heat conduction and a small heat capacity is desirable. However, in order to obtain a force necessary to keep the sealing surface in close contact with a metal material such as copper or aluminum to maintain airtightness, the cross-sectional shape is increased or the length of the claw portion of the holder portion 31 is increased. Since it is necessary to increase the length, the heat capacity increases to some extent.

Next, a third embodiment of the present invention will be described.
FIG. 5 is a cross-sectional view of a jet nozzle according to the third embodiment of the present invention. As shown in FIG. 5, the jet nozzle 40 includes a holder portion 41 instead of the holder portion 31 shown in FIG. 4. About another structure, it is the same as that of the jet nozzle shown in FIG.

  In the present embodiment, the force necessary for keeping the seal surface in close contact and maintaining airtightness is obtained not by the elastic force of the holder part 31 but by the thermal contraction of the holder part 41. That is, in the range in which the target discharge portion 11 is pressed against the support portion 12, the target discharge portion 11 is brought to the support portion 12 by the holder portion 41 having a heat shrinkage amount larger than the total heat shrinkage amount of the target discharge portion 11 and the seal 15. By applying the pressing pressure, it is possible to maintain the airtightness between the target discharge portion 11 and the support portion 12 even if a temperature change occurs.

  As a material of the holder part 41, in order to improve the efficiency of cooling control of xenon, a metal material such as copper or aluminum having good heat conduction and a small heat capacity is desirable. However, the thermal contraction rate of these materials is about 1/10 of the thermal contraction rate of Teflon (registered trademark) used as the material of the seal 15. In such a case, the holder portion 41 has a thermal contraction amount larger than at least the total thermal contraction amount of the target discharge portion 11 and the seal 15 in a range where the target discharge portion 11 is pressed against the support portion 12. . However, in order to obtain the amount of heat shrinkage required to keep the sealing surface in close contact with a metal material such as copper or aluminum, the length of the barrel of the holder portion 41 needs to be increased. As in the second embodiment, the heat capacity increases to some extent.

Next, a fourth embodiment of the present invention will be described.
FIG. 6 is a cross-sectional view of a jet nozzle according to the fourth embodiment of the present invention. As shown in FIG. 6, the jet nozzle 50 removes the leaf spring 14 from the jet nozzle shown in FIG. 1 and includes a seal 51 instead of the seal 15. About another structure, it is the same as that of the jet nozzle shown in FIG.

  In the present embodiment, the force necessary to keep the seal surface in close contact and maintain airtightness is obtained by the repulsive force of the spring-loaded seal 51 for internal pressure. That is, by applying a pressure that presses the target discharge portion 11 against the support portion 12 due to the repulsive force of the seal 51, the airtightness between the target discharge portion 11 and the support portion 12 is maintained even if a temperature change occurs. Making it possible.

  In the present embodiment, the support portion 12 is provided with a stopper so that the repulsive force of the seal 51 set at the time of fixing is reproducible. That is, at the time of fixing, the repelling force of the seal 51 is made constant by abutting and fixing the holder portion 13 against the stopper. Further, by changing the position of the stopper, it is possible to cope with an arbitrary temperature and internal pressure.

  The seal 51 is ring-shaped, has a C-shaped cross section, and is formed so that the opening is on the inside. The seal 51 is formed of SUS having a Teflon (registered trademark) coating on the surface, and can be used in the same manner as an O-ring.

  Therefore, when the pressure of the target material in the C-shaped portion of the seal 51 is increased, the target discharge portion 11 and the seal 51 are more closely contacted, and further, the seal 51 and the support portion 12 are more closely contacted. , Sealing properties can be improved.

  The present invention can be used for a jet nozzle for emitting a target substance in a light source device that generates EUV light.

It is sectional drawing of the jet nozzle which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the shape of the leaf | plate spring used in the 1st Embodiment of this invention. It is sectional drawing of the jet nozzle which concerns on the modification of the 1st Embodiment of this invention. It is sectional drawing of the jet nozzle which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the jet nozzle which concerns on the 3rd Embodiment of this invention. It is sectional drawing of the jet nozzle which concerns on the 4th Embodiment of this invention. It is a figure which shows the structure of the conventional light source device. It is sectional drawing of the conventional jet nozzle.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20, 30, 40, 50 ... Jet nozzle, 11 ... Target discharge | release part, 12, 21 ... Support part, 13, 31, 41 ... Holder part, 14 ... Leaf spring, 15, 51 ... Seal, 22 ... Pulse tube 23 ... Thermistor

Claims (7)

A jet nozzle that is used in a light source device that generates extreme ultraviolet light and emits a target material that is a target irradiated with a laser beam to generate extreme ultraviolet light,
A target discharge section for forming a first flow path therein and discharging a target material supplied to one end of the first flow path from the other end of the first flow path;
A second flow path and a cooling chamber are formed therein, and the target material supplied to one end of the second flow path is cooled and supplied to the target discharge portion from the other end of the second flow path. A support for,
Fixing means for removably fixing the target discharge portion to the support portion so that the first flow channel and the second flow channel communicate with each other;
A jet nozzle comprising:   A seal member inserted between the target discharge portion and the support portion, wherein the seal member has a hollow region for communicating the first flow path and the second flow path. The jet nozzle according to claim 1, further comprising: The fixing means is
A hollow space is formed that encloses the target discharge part and the support part, and one end of the tubular holder part can be integrated with the support part,
At the other end of the holder part, a pressure application part that applies pressure to press the target discharge part against the support part;
The jet nozzle according to claim 1, comprising: The pressure application unit includes a leaf spring that presses the target discharge unit against the support unit,
The jet nozzle according to claim 3.   The fixing means is formed with a hollow space that encloses the target discharge portion and the support portion, and one end is a tubular holder portion that can be integrated with the support portion, and the target discharge portion is used as the support portion. The jet nozzle according to claim 1, comprising a holder portion having elasticity for applying a pressing pressure.   The fixing means is formed with a hollow space that encloses the target discharge portion and the support portion, and one end is a tubular holder portion that can be integrated with the support portion, and the target discharge portion is used as the support portion. 3. The jet nozzle according to claim 2, further comprising a holder portion having a heat shrinkage amount that is at least larger than a total heat shrinkage amount of the target discharge portion and the seal member in a range to be pressed. The fixing means is
A hollow space is formed that encloses the target discharge part and the support part, and one end of the tubular holder part can be integrated with the support part,
A seal member inserted between the target discharge portion and the support portion, wherein a hollow region for communicating the first flow path and the second flow path is formed, and the target discharge section A spring-loaded seal member for applying a pressure to press the holder part against the holder part;
The jet nozzle according to claim 1, comprising:

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