ARRANGEMENT AND METHOD FOR THE GENERATION OF EUV RADIATION OF HIGH AVERAGE OUTPUT

Abstract

The invention is directed to an arrangement and a method for the generation of EUV radiation of high average output, preferably for the wavelength region of 13.5 nm for use in semiconductor lithography. It is the object of the invention to find a novel possibility for generating EUV radiation of high average output which permits a time-multiplexing of the radiation of a plurality of source modules in a simple manner without overloading the source modules and without requiring extremely high rotational speeds of optical-mechanical components. This object is met, according to the invention, in that a plurality of identically constructed source modules which are arranged so as to be distributed around a common optical axis are directed to a rotatably mounted reflector arrangement which successively couples in the beam bundles of the source modules along the optical axis. The reflector arrangement has a drive unit by which a reflecting optical element is adjustable so as to be stopped temporarily in angular positions that are defined for the source modules and is oriented to the next source module in intervals between two exposure fields of a wafer by means of control signals emitted by an exposure system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 shows a schematic view of the invention with two source modules with two angular adjustments of the reflector arrangement;

FIG. 2 shows a schematic diagram illustrating the wafer exposure in semiconductor lithography;

FIG. 3 shows a construction of the invention with two source modules, an auxiliary laser beam and two position-sensitive detectors;

FIG. 4 shows the exposure schedule for a 300-mm wafer in an arrangement with three source modules;

FIG. 5 shows the EUV source modules and rotary mirror controlled by control signals of the exposure system and position-sensitive detectors; and

FIG. 6 shows a construction of the invention with an auxiliary mirror and monitoring detector for additional source module testing in a passive circuit.

Claims

1. An arrangement for generating EUV radiation of high average output for the lithographic exposure of wafers comprising: a vacuum chamber being provided for the generation of radiation, said vacuum chamber having an optical axis for the EUV radiation when it exits the vacuum chamber;a plurality of identically constructed source modules being arranged so as to be distributed around the optical axis of the vacuum chamber, from which source modules a beam bundle generated from EUV radiation-emitting plasma is directed to a common intersection point with the optical axis;a rotatably mounted reflector arrangement being arranged at the common intersection point of the beam bundles, which reflector arrangement couples the beam bundles prepared by the source modules into the optical axis in series;said reflector arrangement having a reflecting optical element which is mounted so as to be rotatable around an axis of rotation coaxial to the optical axis and which communicates with a drive unit and is adjustable on demand so as to be stopped temporarily in angular positions that are defined for the source modules; andsaid reflector arrangement communicating with an exposure system for lithographic exposure in order to initiate an orientation of the reflecting optical element to the next source module in intervals between exposures by control signals emitted by the exposure system.

2. The arrangement according to claim 1, wherein the drive unit has a rotor which is rotatable around the optical axis by increments, and the reflecting optical element is directly connected to the rotor.

3. The arrangement according to claim 2, wherein a plane mirror is provided as reflecting optical element.

4. The arrangement according to claim 2, wherein a suitably curved mirror is provided as reflecting optical element for additional focusing of the beam bundles of the source modules.

5. The arrangement according to claim 2, wherein a plane optical grating is provided as reflecting optical element.

6. The arrangement according to claim 2, wherein a curved optical grating is provided as reflecting optical element for additional focusing of the beam bundles of the source modules.

7. The arrangement according to claim 1, wherein an additional, auxiliary laser beam and position-sensitive detectors associated with the source modules for detecting and adjusting the angle of rotation of the reflecting optical element are provided.

8. The arrangement according to claim 5, wherein the reflecting optical element is constructed as a meandering grating with a suitable groove depth and grating constant.

9. The arrangement according to claim 5, wherein the reflecting optical element is constructed so as to be spectrally selective for the desired bandwidth of the EUV radiation that is transmissible by the optics downstream.

10. The arrangement according to claim 1, wherein the reflector arrangement has a stepper motor as drive unit.

11. The arrangement according to claim 1, wherein the reflector arrangement is controlled by control signals of position-sensitive detectors in addition to the control signals from the exposure system.

12. The arrangement according to claim 1, wherein the reflector arrangement has two reflecting optical elements, a main mirror and an auxiliary mirror, wherein the main mirror is provided for coupling in the EUV radiation of the active source module along the optical axis and the auxiliary mirror is designed to deflect EUV radiation of a passive source module to a monitoring detector for measuring output parameters.

13. The arrangement according to claim 1, wherein the collector optics used in the individual source modules are grazing incidence optics.

14. The arrangement according to claim 13, wherein the collector optics are a nested Wolter collector.

15. The arrangement according to claim 1, wherein the collector optics used in the individual source modules are multilayer optics.

16. The arrangement according to claim 15, wherein a Schwarzschild collector is used as collector optics.

17. The arrangement according to claim 1, wherein the source units in the individual source modules are constructed as gas discharge sources.

18. The arrangement according to claim 17, wherein gas discharge sources have discharge arrangements with rotary electrodes.

19. The arrangement according to claim 17, wherein the individual source modules have separate high-voltage charging modules.

20. The arrangement according to claim 17, wherein the individual source modules share a common high-voltage charging module.

21. A method for the generation of EUV radiation of high average output for the lithographic exposure of wafers in which a plurality of identically constructed source modules which are arranged in a vacuum chamber so as to be uniformly distributed around an optical axis of the vacuum chamber are triggered successively for generating beam bundles of EUV radiation-emitting plasma in order to couple in their beam bundles in direction of the common optical axis by means of a reflector arrangement which is mounted so as to be rotatable, comprising the following steps: 1) rotating the reflector arrangement for coupling in the beam bundle of a first source module along the optical axis simultaneous with the adjustment of a first exposure field of the wafer in an exposure system for lithographic exposure;2) triggering the first source module in a burst regime with a high pulse repetition frequency and enough pulses so that the entire first exposure field is completely exposed by pulses from the first source module;3) rotating the reflector arrangement for coupling in a next source module simultaneous with the adjustment of a next exposure field within an interval between exposures after the preceding exposure of an exposure field;4) triggering the next coupled-in source module in a burst regime with the same pulse repetition frequency and number of pulses as those for the first exposure field so that the current exposure field is completely exposed with pulses from this source module; and5) repeating steps 3 and 4, and coupling in all of the source modules one after the other for the complete exposure of a respective exposure field until the last exposure field of the wafer is exposed.