JP-2026514352-A - Apparatus and method for acoustic control in a laser chamber

Abstract

This device generates laser radiation from an electrical discharge within a gap. Within the discharge chamber, the discharge reflects acoustic waves from the internal surfaces of the chamber. The gap is angled relative to the surfaces of the chamber's internal structures, so that the acoustic waves reflected by these surfaces do not reflect back to their origin, thus not interfering with the laser's operation, especially at high repetition rates. [Selection Diagram] Figure 7

Inventors

• スタイガー，トーマス，ディクソン

Assignees

• サイマー リミテッド ライアビリティ カンパニー

Dates

Publication Date

20260511

Application Date

20240306

Priority Date

20230328

Claims (19)

1. A chamber wall extending in the first direction, A first electrode having a first electrode discharge surface, A second electrode having a second electrode discharge surface, A discharge chamber equipped with, The first electrode discharge surface and the second electrode discharge surface define a discharge gap, and the first and second electrodes are configured to induce a plasma discharge within the discharge gap. The first and second electrode discharge surfaces extend parallel to each other in a second direction at a certain angle with respect to the first direction, The first electrode has a top surface parallel to the chamber wall, and therefore the first electrode has a wedge-shaped cross-section between the first electrode discharge surface and the top surface. Discharge chamber.
2. The discharge chamber according to claim 1, wherein the first electrode is a cathode and the top surface is attached to the chamber wall.
3. The discharge chamber according to claim 1, further comprising an electrode support mechanically coupled to the second electrode and positioned to support the second electrode within the discharge chamber, wherein the magnitude of the angle is selected to prevent acoustic waves generated from an originating region within the discharge gap during a discharge within the discharge gap from being reflected back to the originating region by the electrode support during the next discharge.
4. The discharge chamber according to claim 3, wherein the magnitude of the angle is in the range of 0.5 degrees to 10 degrees.
5. The discharge chamber according to claim 1, further comprising an electrode support mechanically coupled to the second electrode and positioned to support the second electrode within the discharge chamber, wherein at least a portion of the electrode support is disposed within a distance D from the discharge gap.
6. The discharge chamber according to claim 5, wherein the distance D is less than 2 inches.
7. The discharge chamber according to claim 1, further comprising a pre-onizer extending parallel to the chamber wall and positioned laterally close to the first electrode, wherein at least a portion of the pre-onizer is positioned within a distance D from the discharge gap.
8. The discharge chamber according to claim 7, wherein the distance D is less than 2 inches.
9. The discharge chamber according to claim 7, wherein the magnitude of the angle is selected to prevent acoustic waves generated from the starting region within the discharge gap during discharge from being reflected back to the starting region by the play-onizer during the next discharge.
10. The discharge chamber according to claim 9, wherein the magnitude of the angle is in the range of 0.5 degrees to 10 degrees.
11. The discharge chamber according to claim 1, further comprising an insulator disposed parallel to the chamber wall and positioned laterally close to the first electrode proximal to the discharge gap.
12. The discharge chamber according to claim 11, wherein the magnitude of the angle is selected to prevent acoustic waves generated from the starting region within the discharge gap during discharge from being reflected back to the starting region by the insulator during subsequent discharge.
13. The discharge chamber according to claim 12, wherein the magnitude of the angle is in the range of 0.5 degrees to 10 degrees.
14. A laser chamber extending along the optical axis of the chamber in a first direction, A first elongated electrode, having a first electrode discharge surface, is disposed within the laser chamber. A second elongated electrode, having a second electrode discharge surface, is disposed within the laser chamber. A device equipped with, The first electrode discharge surface and the second electrode discharge surface are arranged with a gap between them, extending parallel to each other in the second direction at a certain angle with respect to the first direction, defining a discharge gap extending in the second direction. At least one acoustic reflecting surface is positioned near the discharge gap and extends in the first direction in close proximity to one of the first electrode and the second electrode, The magnitude of the angle is selected to prevent acoustic waves generated from an originating region within the discharge gap during a discharge within the discharge gap from being reflected back to the originating region by the at least one acoustic reflecting surface during the next discharge.
15. The apparatus according to claim 14, wherein the at least one acoustic reflective surface comprises the surface of a pre-onizer extending in the first direction and disposed in close proximity to the first elongated electrode in the lateral direction, and at least a portion of the pre-onizer is further disposed within a distance D from the discharge gap.
16. The apparatus according to claim 15, wherein the distance D is less than 2 inches.
17. The apparatus according to claim 14, wherein the at least one acoustic reflecting surface extends in the first direction and comprises an insulator proximal to the discharge gap.
18. The apparatus according to claim 14, wherein the at least one acoustic reflective surface comprises an electrode support surface that is arranged to mechanically support the second electrode and extends in the first direction proximal to the discharge gap.
19. The apparatus according to claim 14, wherein the magnitude of the angle is in the range of 0.5 degrees to 10 degrees.

Description

(Cross-reference of related applications) [0001] This application claims priority to U.S. Application No. 63/455,054, filed on 28 March 2023, entitled “LASER CHAMBER HAVING DISCHARGE GAP WITH ACOUSTIC CONTROL,” which is incorporated herein by reference in its entirety. [0002] The subject matter disclosed relates to a laser discharge chamber in which a discharge in the discharge region generates laser radiation and also generates acoustic disturbances that can be unnecessarily reflected back into the discharge region. [0003] Photolithography is a process used to pattern semiconductor circuit elements onto substrates such as silicon wafers. A photolithography radiation source provides deep ultraviolet (DUV) light (wavelengths ranging from approximately 100 nanometers (nm) to approximately 400 nm) used to expose the photoresist on the wafer. In many cases, the radiation source is a laser source, and the radiation is a pulsed laser beam. The radiation beam passes through a beam delivery unit, then a reticle or mask, and is subsequently projected onto the photoresist-coated silicon wafer. In this way, the chip design is patterned onto the photoresist, and then etched and cleaned. [0004] In many systems that generate laser beams (such as laser generators) or employ laser beams (such as photolithography systems), there is an optical train containing one or more optical components (such as mirrors, gratings, prisms, optical switches, filters, etc.). The optical components in the optical train can reflect, process, filter, modify, focus, expand, etc., the laser beam, either entirely or partially, to obtain one or more desired laser beam outputs. [0005] In such systems, the laser beam is generated by generating a discharge in the discharge (inter-electrode) region of one or more laser discharge chambers. One of the challenges in designing and using these systems is that the discharge used to generate the laser radiation also generates strong acoustic waves within the discharge region, causing gas density modulation as it propagates within the laser discharge chamber. Surfaces within the laser discharge chamber can reflect these acoustic waves back into the discharge region, potentially negatively impacting the laser's performance. In particular, these reflected waves can consequently cause round-trip time-of-flight resonance due to pulse delay or discharge repetition rate. [0006] In these circumstances, the need for the subject matter of this disclosure arises. [0007] The following provides a brief overview of one or more embodiments of the present invention to deepen the basic understanding of the present invention. This overview does not comprehensively describe all conceivable embodiments, nor does it identify any particular element of any embodiment as important or critical, nor does it limit the scope of some or all embodiments. The sole purpose of this overview is to present in a concise manner some concepts related to one or more embodiments as a prerequisite for the more detailed description that follows. [0008] According to one aspect of one embodiment, a discharge chamber is disclosed comprising a chamber wall extending in a first direction, a first electrode having a first electrode discharge surface, and a second electrode having a second electrode discharge surface, wherein the first and second electrode discharge surfaces define a discharge gap, the first and second electrodes are configured to induce a plasma discharge within the discharge gap, the first and second electrode discharge surfaces extend parallel to each other in a second direction at a certain angle with respect to the first direction, the first electrode has a top surface parallel to the chamber wall, and therefore the first electrode has a wedge-shaped cross-section between the first electrode discharge surface and the top surface. [0009] The first electrode may be a cathode, and its top surface may be attached to the chamber wall. The discharge chamber further comprises an electrode support mechanically coupled to the second electrode and positioned to support the second electrode within the discharge chamber, the magnitude of which is selected to prevent acoustic waves originating from the origin region in the discharge gap during discharge in the discharge gap from being reflected back to the origin region by the electrode support during subsequent discharges. The magnitude of the angle may range from 0.5 degrees to 10 degrees. [0010] The discharge chamber further comprises an electrode support mechanically coupled to the second electrode and positioned to support the second electrode within the discharge chamber, with at least a portion of the electrode support positioned within a distance D from the discharge gap. The distance D may be less than 2 inches. [0011] The discharge chamber may further comprise a pre-onizer extending parallel to the chamber wall and positioned laterally close to the first electrode, with at least a portio