US-12620776-B2 - Control device, control system, method for operating a control system

US12620776B2US 12620776 B2US12620776 B2US 12620776B2US-12620776-B2

Abstract

A control system for frequency control of a laser module, comprising at least one laser module for generating laser radiation, at least one control device coupled or configured to couple to the laser module, and at least one optical resonator coupled or configured to couple to the control device, wherein the control device comprises a semiconductor substrate, a first Pound-Drever-Hall system arranged on the semiconductor substrate and at least one second Pound-Drever-Hall system arranged on the semiconductor substrate, wherein the laser module is coupled to the first Pound-Drever-Hall system of the control device and is configured to couple to the at least second Pound-Drever-Hall system of the control device, wherein the first Pound-Drever-Hall system is coupled to the optical resonator and wherein the second Pound-Drever-Hall system is configured to couple to the optical resonator, and wherein the number of Pound-Drever-Hall systems is greater than the number of laser modules or optical resonators.

Inventors

Arian Kriesch
Matthias Manger
Claudius Weimann
Ulrich Vogl

Assignees

CARL ZEISS SMT GMBH

Dates

Publication Date: 20260505
Application Date: 20220729
Priority Date: 20200131

Claims (18)

1 . A control system for frequency control of a laser module, comprising: at least one laser module for generating laser radiation; at least one control device coupled or configured to couple to the at least one laser module; and at least one optical resonator coupled or configured to couple to the at least one control device; wherein the at least one control device comprises a semiconductor substrate, a first Pound-Drever-Hall system arranged on the semiconductor substrate and at least one second Pound-Drever-Hall system arranged on the semiconductor substrate, wherein the at least one laser module is configured to couple to and decouple from the first Pound-Drever-Hall system of the at least one control device and is configured to couple to the at least one second Pound-Drever-Hall system of the at least one control device, wherein the first Pound-Drever-Hall system is coupled to the at least one optical resonator and wherein the at least one second Pound-Drever-Hall system is configured to couple to the at least one optical resonator, wherein a number of Pound-Drever-Hall systems is greater than a number of laser modules or optical resonators of the control system; wherein the at least one laser module is coupled to at least two Pound-Drever-Hall systems; and wherein the laser radiation of the first Pound-Drever-Hall system and the laser radiation of the at least one second Pound-Drever-Hall system have a phase offset with respect to one another.
2 . The control system of claim 1 , further comprising at least one driver configured to drive the first Pound-Drever-Hall system and the at least one second Pound-Drever-Hall system for carrying out a coupling or decoupling.
3 . The control system of claim 2 , wherein the at least one driver is a matrix circuit.
4 . The control system of claim 1 , further comprising a modulator configured to generate the phase offset, wherein the modulator is connected between the at least one laser module and the first Pound-Drever-Hall system and between the at least one laser module and the at least one second Pound-Drever-Hall system.
5 . The control system of claim 4 , wherein the modulator comprises a comb line spacing controller.
6 . The control system of claim 1 , further comprising a photodetector, wherein the photodetector is connectable or connected to a reference light source.
7 . The control system of claim 1 , further comprising a first wavelength-selective optical switch and at least one second wavelength-selective optical switch.
8 . The control system of claim 1 , further comprising a Proportional-Integral-Derivative (PID) controller, wherein a derivative element of the PID controller is not equal to zero.
9 . The control system of claim 1 , wherein the first Pound-Drever-Hall system and the at least one second Pound-Drever-Hall system are driveable separately.
10 . The control system of claim 9 , further comprising at least one controller configured to drive the first Pound-Drever-Hall system and the at least one second Pound-Drever-Hall system.
11 . The control system of claim 1 , wherein at least one of the first Pound-Drever-Hall system or the at least one second Pound-Drever-Hall system comprises at least one driveable phase modulator and/or at least one photodetector.
12 . The control system of claim 1 , wherein the first Pound-Drever-Hall system or the at least one second Pound-Drever-Hall system comprises at least one electronic component.
13 . The control system of claim 1 , wherein the control system is incorporated into an illumination system for a projection exposure apparatus for EUV lithography, the illumination system comprising a housing enclosing an interior, and at least two optical elements arranged in the housing, wherein the at least two optical elements form an optical resonator.
14 . The control system of claim 1 , wherein the control system is incorporated into a projection system for a projection exposure apparatus for EUV lithography, the projection system comprising a housing enclosing an interior, and at least two optical elements arranged in the housing, wherein the at least two optical elements form an optical resonator.
15 . The control system of claim 1 wherein the control system is incorporated into a projection exposure apparatus for EUV lithography, the projection exposure apparatus comprising: an illumination system and a projection system.
16 . A method for operating a control system, comprising: a) operating a first Pound-Drever-Hall system and a second Pound-Drever-Hall system; b) coupling a laser module to one of the first Pound-Drever-Hall system or the second Pound-Drever-Hall system; c) detecting at least one actual value of a predetermined electrical parameter of the first Pound-Drever-Hall system; d) comparing the at least one actual value with a predetermined setpoint value; e) decoupling the laser module from the first Pound-Drever-Hall system if a determined deviation between the at least one actual value and setpoint value is greater than a predetermined limit deviation; and f) coupling the laser module to the second Pound-Drever-Hall system.
17 . A method for carrying out frequency control for a laser module of a control system, the control system comprising at least one laser module for generating laser radiation; at least one control device coupled or configured to couple to the at least one laser module and at least one optical resonator coupled or configured to couple to the at least one control device, wherein the at least one control device comprises a semiconductor substrate, a first Pound-Drever-Hall system arranged on the semiconductor substrate and at least one second Pound-Drever-Hall system arranged on the semiconductor substrate; the method comprising: a) coupling the at least one laser module to the first Pound-Drever-Hall system, b) generating laser radiation via the at least one laser module and introducing the laser radiation into the first Pound-Drever-Hall system; c) introducing the laser radiation, having a carrier frequency of the laser radiation, into a phase modulator and generating at least one sideband; d) splitting the laser radiation into a first partial radiation, having a carrier frequency of the laser radiation, and a second partial radiation, having a potentially phase-shifted carrier frequency of the laser radiation; e) superimposing the first partial radiation and the second partial radiation; f) monitoring for a predefinable deviation between the first partial radiation and the second partial radiation; g) controlling the carrier frequency of the laser radiation if a deviation between the first partial radiation and the second partial radiation that is greater than the predefinable deviation is identified, wherein the carrier frequency is controlled in such a way that it becomes equal to a reference frequency; h) decoupling the at least one laser module from the first Pound-Drever-Hall system; and i) coupling the at least one laser module to the at least one second Pound-Drever-Hall system.
18 . The method of claim 17 , wherein the frequency control is carried out based on driving a comb line spacing controller.

Description

CROSS-REFERENCE TO RELATED APPLICATION This is a Continuation of International Application PCT/EP2021/050976, which has an international filing date of Jan. 19, 2021, and the disclosure of which is incorporated in its entirety into the present Continuation by reference. This Continuation also claims foreign priority under 35 U.S.C. § 119(a)-(d) to and also incorporates by reference, in its entirety, German Patent Application DE 10 2020 201 211.3 filed on Jan. 31, 2020. FIELD The techniques of this disclosure relate to a control device, comprising a semiconductor substrate and a first Pound-Drever-Hall system arranged on the semiconductor substrate. BACKGROUND The disclosed techniques further relate to a control system, a method for operating the control system, and a projection exposure apparatus comprising such a control system. Control devices of the type mentioned in the Field are known from the related art. In this regard, a control device comprising a semiconductor substrate and a first Pound-Drever-Hall system embodied on the semiconductor substrate is described for example in Idjadi et al., Integrated Pound-Drever-Hall laser stabilization system in silicon, Nature Communications 8, 1-9 (2017). In that case, the control device has the effect that a frequency of a laser radiation emitted by a laser or a laser module is controllable or stabilizable to a predefinable reference frequency in such a way that the frequency of the laser radiation is equal to the reference frequency. In that case, the reference frequency is generated by an element of the control device itself. Further control devices are known from Dreyer, R. W. P. et al., Laser phase and frequency stabilization using an optical resonator, Appl. Phys. B Photophysics Laser Chem. 31, 97-105 (1983) and the documents WO2013/016249A2, US2013/0044772A1, WO2013/040143A2, Alnis et al., Subhertz linewidth diode lasers by stabilization to vibrationally and thermally compensated ultralow-expansion glass Fabry-Perot cavities, Phys. Rev. A—At. Mol. Opt. Phys. 88 (2008), Zhao et al., Sub-Hertz frequency stabilization of a commercial diode laser, Opt. Commun. 283, 4696-4700 (2019), Toptica-Photonics GmbH. Product catalog and data sheets, Tuneable Diode Lasers, copied 2020, page 41 and Biedermann, B., Menlo Systems ORS1500 Optical Reference System: Design and Performance (2013). Against the background above, it is an object of the disclosed techniques to provide an improved control device and an improved control system. SUMMARY According to an aspect, the disclosed techniques provide for at least one second Pound-Drever-Hall system being arranged (e.g., embodied, integrated, monolithically formed, attached, bonded, etc.) on the semiconductor substrate of a control system. Consequently, at least two, in particular more than ten, preferably more than 50, Pound-Drever-Hall systems are embodied on the semiconductor substrate. The advantage here is that a single component or a single control device is made available which includes a plurality of Pound-Drever-Hall systems, which are operable simultaneously. As an alternative to simultaneous operation, the at least second Pound-Drever-Hall system is employable or usable depending on demand. “Depending on demand” means, for example, that the at least one second Pound-Drever-Hall system serves or is provided as a backup system with respect to the first Pound-Drever-Hall system, such that the second Pound-Drever-Hall system takes over or can take over the function or task of the first Pound-Drever-Hall system when, for example, the functionality of the first Pound-Drever-Hall system is faulty, critically degraded or impaired. Furthermore, the control device may be produced in a manner that is cost-effective and saves structural space because the respective Pound-Drever-Hall systems are embodied or able to be embodied on one and the same semiconductor substrate. In accordance with one embodiment, the first Pound-Drever-Hall system and the at least one second Pound-Drever-Hall system are separately driveable. This provides the advantage that the Pound-Drever-Hall systems are operable in a targeted manner, such as independently of one another. By way of example, this ensures that the at least two Pound-Drever-Hall systems can be operated or are operable simultaneously or alternatively in a manner offset in time with respect to one another. In accordance with a further embodiment, the control device includes at least one controller configured to drive the first Pound-Drever-Hall system and the at least one second Pound-Drever-Hall system. The advantage here is that the plurality of Pound-Drever-Hall systems are driveable in a simple manner, such as centrally driven by a single controller. The controller is preferably a separate controller, i.e., not embodied on the semiconductor substrate, which is connected to the control device in terms of signalling, such as in a wire-based manner. In accordance with a further embodimen