JP4517147B2 - Extreme ultraviolet light source device - Google Patents

Description

The present invention relates to a laser-produced plasma light source device and a liquid target recovery device that obtains light of a predetermined wavelength by supplying a liquid target continuously or intermittently to a laser light irradiation region to emit plasma.
The light source device can be used as a light source for photolithography exposure.

  In a laser-produced plasma light source device that obtains light of a predetermined wavelength by continuously or intermittently supplying the liquid target to a laser light irradiation region to emit plasma, laser light in a plasma light emitting chamber that is maintained in a vacuum state A liquid target discharge nozzle that discharges a liquid target to an irradiation position, and a liquid that is disposed at a position facing the liquid target discharge nozzle and that is discharged from the liquid target discharge nozzle and passes through the laser light irradiation position A target collection cylinder is used.

The liquid target recovery cylinder is disposed at a position facing the liquid target discharge nozzle, and the liquid target discharged from the liquid target discharge nozzle passes through the laser light irradiation position before the liquid target recovery cylinder. It enters the collection cylinder from the tip and is collected.
The inside of the liquid target recovery cylinder is evacuated to a vacuum by an evacuation device, and a tip of the pipe usually has a diameter of several millimeters to 1 cm or a schema for maintaining a degree of vacuum (aperture having a diameter of 100 μm). Is provided.

  The shape and position of the liquid target ejected from the liquid target ejection nozzle to the laser light irradiation position in the plasma emission chamber formed inside the vacuum vessel greatly changes due to its fluid instability in vacuum. For this reason, the liquid target does not flow into the recovery cylinder from the tip of the liquid target recovery cylinder, but is scattered in the vacuum container, which may greatly reduce the degree of vacuum. Decreasing the degree of vacuum is a major obstacle to extracting light with a predetermined wavelength at a high output because light with a predetermined wavelength (for example, extreme ultraviolet light) obtained by plasma emission is absorbed.

In view of the above-described circumstances, the present invention has the following contents (O01) to (O03) as technical problems.
(O01) To prevent the liquid target from being scattered in the vacuum container without being collected in the liquid target collection cylinder due to the fluctuation in shape and position due to fluid instability.
(O02) To prevent the liquid target from scattering into the vacuum vessel and lowering the degree of vacuum in the vacuum vessel.
(O03) To prevent the liquid target from adhering to the liquid target recovery cylinder and growing into icicle-shaped ice.

  Next, the present invention that solves the above problems will be described. In order to facilitate correspondence with the elements of the embodiments described later, the elements of the present invention are those in which the reference numerals of the elements of the embodiments are enclosed in parentheses. Appendices. The reason why the present invention is described in correspondence with the reference numerals of the embodiments described later is to facilitate the understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(First invention)
The plasma light-emitting light source device (1) of the first invention is characterized by comprising the following structural requirements (A01) to (A06).
(A01) Plasma emission chamber (A) maintained in a vacuum state,
(A02) a liquid target discharge nozzle (4) for discharging a liquid target (T) to a laser beam irradiation position (A1) in the vacuum plasma light emitting chamber (A),
(A03) The liquid target (T) which is disposed at a position facing the liquid target discharge nozzle (4) and which has been discharged from the liquid target discharge nozzle (4) and passed through the laser light irradiation position (A1) enters. A liquid target recovery cylinder (9, 13) having an inner recovery cylinder (9) for recovering the liquid target and an outer recovery cylinder (13) disposed so as to surround the outer peripheral surface of the inner recovery cylinder (9);
(A04) Inner recovery cylinder heating device (H1) for heating the tip of the inner recovery cylinder (9),
(A05) An inner collection cylinder exhaust device (S1) for exhausting gas inside (R1) of the inner collection cylinder (9),
(A06) A cylindrical space exhaust device (S2) that exhausts the gas in the cylindrical space (R2) between the outer surface of the inner recovery tube (9) and the inner surface of the outer recovery tube (13).

(Operation of the first invention)
In the plasma light-emitting light source device (1) according to the first aspect of the present invention having the structural requirements (A01) to (A06), the liquid target discharge nozzle (4) is a laser in the plasma light-emitting chamber (A) held in a vacuum state. The liquid target (T) is discharged to the light irradiation position (A1).
The liquid target (T) discharged from the liquid target discharge nozzle (4) and having passed through the laser light irradiation position (A1) is for recovering the liquid target disposed at a position facing the liquid target discharge nozzle (4). Enters the inner collection cylinder (9). The gas inside the inner recovery cylinder (9) is exhausted by the inner recovery cylinder exhaust device (S1). Accordingly, the liquid target (T) discharged from the liquid target discharge nozzle (4) and entering the inner recovery cylinder (9) is discharged into the inner recovery cylinder by the exhaust of the inner recovery cylinder exhaust device (S1). It is discharged from (R1).
The gas in the cylindrical space (R2) between the outer surface of the inner recovery cylinder (9) and the inner peripheral surface of the outer recovery cylinder (13) disposed so as to surround the outer peripheral surface thereof is cylindrical space exhaust. Exhaust by the device (S2). Therefore, the liquid target discharged from the liquid target discharge nozzle (4) and entering the cylindrical space (R2) between the outer surface of the inner recovery tube (9) and the inner surface of the outer recovery tube (13). (T) is discharged from the cylindrical space (R2) along with the exhaust of the cylindrical space exhaust device (S2).
Therefore, it is possible to prevent the liquid target (T) from being scattered in the vacuum container (2) without being collected in the liquid target collecting cylinder (9) due to the fluctuation in shape and position due to the fluid instability. Moreover, it can prevent that the liquid target (T) scatters in a vacuum vessel (2), and the vacuum degree in a vacuum vessel (2) falls.
Since the inner recovery cylinder heating device (H1) heats the tip of the inner recovery cylinder (9), the liquid target (T) attached to the tip of the inner recovery cylinder (9) grows into icicle-shaped ice. Can be prevented.

(First Embodiment 1)
The plasma light-emitting light source device (1) according to the first aspect of the present invention is characterized in that in the first aspect of the present invention, the following structural requirement (A07) is provided.
(A07) An outer recovery cylinder heating device (H2) for heating the tip of the outer recovery cylinder (13).
(Operation of Form 1 of the First Invention)
In the plasma light-emitting light source device (1) according to the first aspect of the first invention having the structural requirement (A07), the outer recovery cylinder heating device (H2) heats the tip of the outer recovery cylinder (13). Therefore, it is possible to prevent the liquid target (T) attached to the tip of the outer recovery cylinder (13) from growing into icicle-shaped ice.

(Second invention)
The liquid target recovery device (K) according to the second aspect of the invention is characterized by including the following structural requirements (A03) to (A06).
(A03) The liquid target (T) which is disposed at a position facing the liquid target discharge nozzle (4) and which has been discharged from the liquid target discharge nozzle (4) and passed through the laser light irradiation position (A1) enters. A liquid target recovery cylinder (9, 13) having an inner recovery cylinder (9) for recovering the liquid target and an outer recovery cylinder (13) disposed so as to surround the outer peripheral surface of the inner recovery cylinder (9);
(A04) Inner recovery cylinder heating device (H1) for heating the tip of the inner recovery cylinder (9),
(A05) An inner collection cylinder exhaust device (S1) for exhausting gas inside (R1) of the inner collection cylinder (9),
(A06) A cylindrical space exhaust device (S2) that exhausts the gas in the cylindrical space (R2) between the outer surface of the inner recovery tube (9) and the inner surface of the outer recovery tube (13).

(Operation of the second invention)
In the liquid target recovery device (K) according to the second aspect of the present invention having the structural requirements (A03) to (A06), the liquid discharged from the liquid target discharge nozzle (4) and passed through the laser light irradiation position (A1) The target (T) enters the inner recovery cylinder (9) for recovering the liquid target disposed at a position facing the liquid target discharge nozzle (4). The gas inside the inner recovery cylinder (9) is exhausted by the inner recovery cylinder exhaust device (S1). Accordingly, the liquid target (T) discharged from the liquid target discharge nozzle (4) and entering the inner recovery cylinder (9) is discharged into the inner recovery cylinder by the exhaust of the inner recovery cylinder exhaust device (S1). It is discharged from (R1).
The gas in the cylindrical space (R2) between the outer surface of the inner recovery cylinder (9) and the inner peripheral surface of the outer recovery cylinder (13) disposed so as to surround the outer peripheral surface thereof is cylindrical space exhaust. Exhaust by the device (S2). Therefore, the liquid target discharged from the liquid target discharge nozzle (4) and entering the cylindrical space (R2) between the outer surface of the inner recovery tube (9) and the inner surface of the outer recovery tube (13). (T) is discharged from the cylindrical space (R2) along with the exhaust of the cylindrical space exhaust device (S2).
Therefore, it is possible to prevent the liquid target (T) from being scattered in the vacuum container (2) without being recovered in the liquid target recovery cylinder (9, 13) due to the fluctuation in shape and position due to the fluid instability. . Moreover, it can prevent that the liquid target (T) scatters in a vacuum vessel (2), and the vacuum degree in a vacuum vessel (2) falls.
Since the inner recovery cylinder heating device (H1) heats the tip of the inner recovery cylinder (9), the liquid target (T) attached to the tip of the inner recovery cylinder (9) grows into icicle-shaped ice. Can be prevented.

The present invention can provide the following effects (E01) to (E03).
(E01) It is possible to prevent the liquid target from being scattered in the vacuum container without being recovered in the liquid target recovery cylinder due to the fluctuation in shape and position due to fluid instability.
(E02) It is possible to prevent the liquid target from scattering into the vacuum container and lowering the degree of vacuum in the vacuum container.
(E03) It is possible to prevent the liquid target from adhering to the liquid target recovery cylinder and growing into icicle-shaped ice.

Example 1
FIG. 1 is an explanatory view of a main part of a first embodiment of a light source device using a laser-produced plasma system according to the present invention.
In FIG. 1, a light source device 1 based on a laser-generated plasma method has a vacuum container 2 in which a plasma emission chamber A is formed. The laser beam L emitted from the laser beam irradiation device 3 supported by the vacuum vessel 2 is focused on the laser beam irradiation position A1 in the plasma emission chamber A. A liquid target discharge nozzle 4 is disposed above the laser light irradiation position A1, and a liquid target recovery device 5 is disposed below.

  The liquid target discharge nozzle 4 has a discharge port at its tip. In order to change (adjust) the diameter of the discharge flow of the liquid target T discharged from the liquid target discharge nozzle 4, the liquid target discharge nozzle 4 is replaced with a different discharge port diameter. Further, the pressure in a liquid target supply tank (not shown) that accommodates the liquid target T supplied to the liquid target discharge nozzle 4 can be adjusted, and the liquid target discharge nozzle 4 discharges the liquid by adjusting the pressure. It is possible to adjust the discharge amount of the liquid target T.

The liquid target T discharged from the liquid target discharge nozzle 4 is irradiated with high-power laser light L when passing through the laser light irradiation position A1, and is used for generation of plasma P (plasma light emission). From the generated plasma P, light having a wavelength corresponding to the target contained in the liquid target T is uniformly emitted in all directions.
The liquid target T that has passed through the laser light irradiation position A1 is recovered by the liquid target recovery device K.

(Liquid target recovery device)
FIG. 2 is a perspective view of the nozzle device N of the present invention.
3 is an enlarged view of the main part of the nozzle device N, FIG. 3A is a longitudinal sectional view taken along line IIIA-IIIA in FIG. 2, FIG. 3B is a view seen from the arrow IIIB-IIIB in FIG. 3A, and FIG. FIG.
In FIG. 1, the liquid target recovery device K includes a turbo molecular pump P1, a roots pump P2, an auxiliary pump P3, an external tank Q, and a nozzle device N.
1 to 3, the nozzle device N has a turbo molecular pump connection flange 6. The lower end of the lower cylindrical member 7 is press-fitted into a through hole 6a (see FIG. 3A) provided at the center of the turbo molecular pump connection flange 6. A ring-shaped plate 8 is brazed to the upper end of the lower cylindrical member 7. A lower end portion of a cylindrical inner collection cylinder 9 is fixed to the inner peripheral surface 8a of the central hole provided in the plate 8 by brazing.
The upper part of the inner recovery cylinder 9 is formed in a conical shape, and an inner target recovery port 9a is formed at the uppermost part.

In FIG. 1, a turbo molecular pump P1 connected to the lower side of the turbo molecular pump connecting flange 6 is configured to supply fluid (air, vapor of the liquid target T, etc.) inside the inner recovery cylinder 9 and the lower cylindrical member 7 to a roots pump P2. To discharge. The roots pump P2 discharges the fluid flowing from the turbo molecular pump P1 to the external tank Q. The external tank Q collects what should be recovered from the fluid flowing in from the roots pump P2, and releases air and the like to the atmosphere.
An inner nozzle heater (inner recovery cylinder heating device) H1 (see the hatched portion in FIG. 2) is wound around the outer surface of the inner recovery cylinder 9.
An inner recovery cylinder exhaust device S1 is constituted by the turbo molecular pump connecting flange 6, the lower cylindrical member 7, the inner recovery cylinder 9, the inner nozzle heater H1, the turbo molecular pump P1, the roots pump P2, the outer tank Q, and the like.

2 and 3, an upper cylindrical member 10 is fixed to the upper surface of the plate 8 by brazing. An exhaust pipe 11a, a heater power supply introduction pipe 11b, and a thermocouple introduction pipe 11c are press-fitted into the side surface of the upper cylindrical member 10. The inside of each of the pipes 11 a to 11 c communicates with the inside of the upper cylindrical member 10. An auxiliary pump connecting flange 12 is attached to the outer end of the exhaust pipe 11a.
A cylindrical outer collection cylinder 13 is fixed to the upper part of the upper cylindrical member 10 by brazing.
An upper end portion of the outer recovery cylinder 13 is formed in a conical shape, and an outer target recovery port 13a is formed at the upper end thereof. The outer target collection port 13a is formed at the same height as or slightly higher than the inner target collection port 9a, and has a larger diameter than the inner target collection port 9a.

When the outer target collection port 13a is formed at a position higher than the same height as the inner target collection port 9a, the target member scattered around by hitting the tapered portion at the tip of the inner collection tube 9 is moved into the outer collection tube 13. Can be easily recovered.
In the first embodiment, the liquid target recovery apparatus K has a dual structure for the recovery ports 9a and 13a, and independently connects the turbo molecular pump P1 and the auxiliary pump P3 to the inner and outer recovery ports 9a and 13a. A, a differential exhaust mechanism in which the pressure inside the outer collection cylinder 13 and the inside of the inner collection cylinder 9 is sequentially increased is configured to maintain a high degree of vacuum in the plasma emission chamber A.

In FIG. 1, the auxiliary pump P <b> 3 connected to the auxiliary pump connecting flange 12 discharges the fluid inside the outer recovery cylinder 13 (such as air and steam of the liquid target T) to the external tank Q. The external tank Q collects what should be recovered from the fluid flowing in from the auxiliary pump P3, and releases air or the like to the atmosphere.
An outer nozzle heater (outer recovery cylinder heating device) H2 is wound around the outer surface of the outer recovery cylinder 13.
The upper cylindrical member 10, the exhaust pipe 11a, the auxiliary pump connection flange 12, the outer recovery cylinder 13, the outer nozzle heater H2, the auxiliary pump P3, the external tank Q, and the like constitute a cylindrical space exhaust device S2.

The inner nozzle heater H1 wound around the outer surface of the inner collecting cylinder 9 is connected to an external power source E (not shown) and supplied with power through a power supply line penetrating the heater power supply introduction pipe 11b. A temperature sensor SN (not shown) that outputs a temperature detection signal of the inner nozzle heater H1 is provided in the vicinity of the inner nozzle heater H1. The temperature sensor SN is connected to a controller C (not shown) through a signal line that penetrates the temperature sensor introduction pipe 11c.
The outer nozzle heater H2 wound around the outer surface of the outer recovery cylinder 13 is supplied with power via a supply line connected to an external power source E (not shown).

  Since the liquid target T discharged from the liquid target discharge nozzle 4 into the plasma light emitting chamber A in a high vacuum state is rapidly cooled by adiabatic expansion, the inner recovery cylinder 9 of the nozzle device N of the liquid target recovery device K, the outer When it comes into contact with the recovery cylinder 13 or the like, icicle-shaped ice grows, preventing continuous recovery of the liquid target T. Therefore, the nozzle device N is configured to prevent the ice of the liquid target T from growing by the heaters H1 and H2.

(Operation of Example 1)
The liquid target T that has passed the laser light irradiation position A1 passes through the inner target recovery port 9a of the nozzle device N of the liquid target recovery device K and enters the inner recovery cylinder 9 inside R1. The inner recovery cylinder exhaust device S1 exhausts the liquid target T that has entered the inside R1 of the inner recovery cylinder 9.
In addition, the liquid target T that has been detached from the inner target recovery port 9a due to the fluctuation in shape and position due to fluid instability of the liquid target T is the outer target recovery port 13a formed around the inner target recovery port 9a. , And enters the cylindrical space R2 between the outer surface of the inner recovery cylinder 9 and the inner peripheral surface of the outer recovery cylinder 13. The outer recovery cylinder exhaust device S2 exhausts the liquid target T that has entered the cylindrical space R2.

Therefore, in the nozzle device N of the liquid target recovery device K of the present invention, when the liquid target T does not enter the inner target recovery port 9 of the inner recovery cylinder 9 due to the fluctuation of the shape and position due to the fluid instability, the outer side with the wider aperture It enters the cylindrical space R2 from the target recovery port 13a.
Thereby, it is possible to prevent the liquid target T that has not been collected in the inner collection cylinder 9 from being scattered in the vacuum container A. Further, it is possible to prevent the liquid target T from being scattered in the vacuum container A and the vacuum degree in the vacuum container A from being lowered.

An inner nozzle heater H1 wound around the outer surface of the inner recovery cylinder 9 heats the inner nozzle 9. The heated inner collection cylinder 9 prevents the liquid target T adhering to the tip of the inner collection cylinder 9 from being cooled and frozen.
The outer nozzle heater H2 wound around the outer surface of the outer collection cylinder 13 heats the outer nozzle 13. The heated outer collection cylinder 13 prevents cooling and freezing of the liquid target T adhering to the tip of the outer collection cylinder 13.
Therefore, the nozzle device N of the liquid target device K of the present invention is not collected by the inner collection cylinder 9 but is attached to the tip of the inner collection cylinder 9 or the tip of the inner and outer peripheral surfaces of the outer collection cylinder 13. It is possible to prevent the liquid target T from growing into icicle-shaped ice.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Examples of modifications of the present invention are illustrated below.
(H01) For the liquid target of the present invention, it is possible to use a solution in which a target halogen or lithium compound salt or the like is dissolved in a polar solvent such as water, methanol, or ethanol. .

FIG. 1 is an explanatory view of a main part of a first embodiment of a light source device using a laser-produced plasma system according to the present invention. FIG. 2 is a perspective view of the nozzle device N of the present invention. 3 is an enlarged view of a main part of the nozzle device N, FIG. 3A is a longitudinal sectional view taken along line IIIA-IIIA in FIG. 2, FIG. 3B is a view seen from the arrow IIIB-IIIB in FIG. 3A, and FIG. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Plasma emission light source device 4 ... Liquid target discharge nozzle 9 ... Inner collection cylinder 13 ... Outer collection cylinder 9, 13 ... Liquid target collection cylinder A ... Plasma emission chamber A1 ... Laser light irradiation position H1... Inner collection cylinder heating device H2... Outer collection cylinder heating device R1... Inner collection cylinder interior R2... Cylindrical space S1. -Cylindrical space exhaust device T ... liquid target,

Claims (3)

A plasma light-emitting light source device comprising the following structural requirements (A01) to (A06),
(A01) Plasma light emitting chamber maintained in a vacuum state,
(A02) a liquid target discharge nozzle for discharging a liquid target to a laser light irradiation position in the vacuum plasma emission chamber;
(A03) An inner recovery cylinder for recovering a liquid target that is disposed at a position facing the liquid target discharge nozzle and into which a liquid target discharged from the liquid target discharge nozzle and passed through the laser light irradiation position enters, and the inner side A liquid target recovery cylinder having an outer recovery cylinder disposed so as to surround the outer peripheral surface of the recovery cylinder;
(A04) Inner recovery cylinder heating device for heating the tip of the inner recovery cylinder,
(A05) An inner recovery cylinder exhaust device that exhausts gas inside the inner recovery cylinder,
(A06) A cylindrical space exhaust device that exhausts gas in a cylindrical space between the outer surface of the inner recovery cylinder and the inner surface of the outer recovery cylinder. The plasma emission light source device (A07) according to claim 1, wherein the outer collection tube heating device heats the tip of the outer collection tube. The liquid target collection | recovery apparatus provided with the following structural requirements (A03)-(A06).
(A03) An inner recovery cylinder for recovering a liquid target that is disposed at a position facing the liquid target discharge nozzle and into which a liquid target that has been discharged from the liquid target discharge nozzle and passed through a laser beam irradiation position enters, and the inner recovery A liquid target recovery cylinder having an outer recovery cylinder disposed so as to surround the outer peripheral surface of the cylinder;
(A04) Inner recovery cylinder heating device for heating the tip of the inner recovery cylinder,
(A05) An inner recovery cylinder exhaust device that exhausts gas inside the inner recovery cylinder,
(A06) A cylindrical space exhaust device that exhausts gas in a cylindrical space between the outer surface of the inner recovery cylinder and the inner surface of the outer recovery cylinder.

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