CN-121986304-A - Inspection device, wedge system for reducing aberrations and method of making same

CN121986304ACN 121986304 ACN121986304 ACN 121986304ACN-121986304-A

Abstract

A method of reducing optical aberrations in an optical system includes determining aberrations caused by the optical system. A wedge system is determined that includes transmitting a first radiation beam having a first wavelength through an optical system. The wedge system includes a radiation curable adhesive disposed between the first wedge and the second wedge. Determining further includes analyzing the first beam using a detector disposed downstream of the wedge system to determine aberrations. The method further includes curing the radiation-cured adhesive based on the analysis of the first beam. Curing includes using a spatial light modulator to adjust an intensity distribution of a second radiation beam having a second wavelength different from the first wavelength based on the analysis of the first beam. Curing also includes directing a second beam to the radiation-cured adhesive to cause the position-dependent optical property at the radiation-cured adhesive.

Inventors

YANG ZIYI

Assignees

ASML荷兰有限公司

Dates

Publication Date: 20260505
Application Date: 20240802
Priority Date: 20230829

Claims (15)

1. A method of reducing optical aberrations in an optical system, the method comprising: Determining aberrations caused by the optical system, comprising: a wedge system transmitting a first beam of radiation having a first wavelength through the optical system, the wedge system comprising a first wedge and a second wedge and a radiation curable adhesive disposed between the first wedge and the second wedge, and Analyzing the first beam using a detector disposed downstream of the wedge system to determine the aberrations, and Based on the analysis of the first beam, curing the radiation curable adhesive, comprising: Adjusting an intensity distribution of a second beam of radiation based on analysis of the first beam using a spatial light modulator, wherein the second beam has a second wavelength different from the first wavelength, and The second beam is directed to the radiation-curable adhesive to cause a position-dependent optical property at the radiation-curable adhesive to reduce the aberration, wherein the radiation-curable adhesive is responsive to the second wavelength.
2. The method of claim 1, further comprising: determining the effectiveness of curing in reducing the aberrations via measurement using the detector, comprising: transmitting a third beam of radiation having the first wavelength through the wedge system, and The transmitted third beam is analyzed via the detector to determine a change in the aberration.
3. The method of claim 2, wherein the determining of the effectiveness comprises determining whether a degree of the aberration meets a threshold.
4. The method of claim 2, further comprising: Based on the determination of efficacy, further curing the radiation curable adhesive, comprising: adjusting an intensity distribution of a fourth beam of radiation based on the determination of the efficacy using the spatial light modulator, wherein the fourth beam has the second wavelength, and The fourth beam is directed to the radiation curable adhesive to adjust the position dependent optical property at the radiation curable adhesive.
5. The method of claim 4, further comprising: The effectiveness of the further curing is determined via measurements using the detector.
6. The method of claim 1, further comprising: An optical objective for directing the first beam or a portion of the first beam through the optical system, and The first beam or the portion of the first beam is reflected at the substrate.
7. The method of claim 6, wherein the analysis of the first beam to determine the aberration includes determining a contribution of the optical objective lens to the aberration having a numerical aperture of approximately 0.5 or greater.
8. The method of claim 6, wherein analyzing the first beam comprises analyzing the first beam or the portion of the first beam using the detector disposed downstream of the wedge system, the optical objective, and the substrate.
9. The method according to claim 6, wherein: The detector is a first detector; The portion is a first portion; transmitting a second portion of the first beam to a second detector along a path that does not include the optical objective and the substrate, and The analyzing of the first beam further comprises analyzing the second portion of the first beam using the second detector.
10. The method of claim 6, wherein the wedge system is disposed downstream of the optical objective and the substrate.
11. The method according to claim 6, wherein: the wedge system is a first wedge system disposed upstream of the substrate; the optical system includes a second wedge system including a radiation curable adhesive disposed between two wedges disposed downstream of the substrate, and Transmitting the first beam through the wedge system includes transmitting the first beam through the first wedge system and the second wedge system.
12. The method of claim 1, further comprising assembling the first wedge and the second wedge such that a thickness of the radiation curable adhesive is substantially constant.
13. The method of claim 12, wherein the thickness is about 50 microns or less.
14. The method according to claim 1, wherein: the radiation curable adhesive is responsive to ultraviolet wavelengths, and The second wavelength is in a wavelength range including an ultraviolet range.
15. The method of claim 1, wherein the first wavelength is in a wavelength range comprising an infrared range and a visible range.

Description

Inspection device, wedge system for reducing aberrations and method of making same Cross Reference to Related Applications The present application claims priority from U.S. application 63/535,149, filed on 8/29 of 2023 and incorporated herein by reference in its entirety. Technical Field The present disclosure relates to metrology systems, such as optical sensors for inspection measurements used in lithography systems and processes. Background A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. For example, lithographic apparatus can be used to manufacture Integrated Circuits (ICs). In this example, a patterning device (which may be a mask or a reticle) may be used to generate a circuit pattern to be formed on each layer of the IC. The pattern may be transferred onto a target portion (e.g., including a portion of a die, one or more dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (photoresist or simply "resist") provided on the substrate. Typically, a single substrate will contain a network of adjacent target portions that are continuously patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through the radiation beam in a given direction (the "scanning" -direction) while synchronously scanning the target portion parallel or anti-parallel to this scanning direction. During lithographic operations, different processing steps may require different layers to be sequentially formed on the substrate. Therefore, it may be necessary to position the substrate with high accuracy relative to the previous pattern formed thereon. Typically, the alignment mark is placed on the substrate to be aligned and is positioned with reference to the second object. The lithographic apparatus may use an alignment apparatus to detect the position of the alignment marks and use the alignment marks to align the substrate to ensure accurate exposure from the mask. Misalignment between alignment marks at two different layers is measured as overlay error. To monitor the lithographic process, parameters of the patterned substrate are measured. Parameters may include, for example, overlay errors between successive layers formed in or on the patterned substrate and critical linewidths of the developed photoresist. The measurement may be performed on a product substrate and/or a dedicated metrology target. There are various techniques for measuring microstructures formed in a photolithographic process, including the use of scanning electron microscopes and various specialized tools. A fast and non-invasive form of specialized inspection tool is a scatterometer in which a beam of radiation is directed onto a target on the surface of a substrate and properties of the scattered or reflected beam are measured. By comparing the properties of the beam before and after reflection or scattering by the substrate, the properties of the substrate can be determined. This may be done, for example, by comparing the reflected beam with data stored in a library of known measurements associated with known substrate properties. A spectroscatterometer directs a broadband radiation beam onto a substrate and measures the spectrum (intensity as a function of wavelength) of the radiation scattered into a particular narrow angular range. In contrast, angle-resolved scatterometers use a monochromatic radiation beam and measure the intensity of scattered radiation as a function of angle. Such optical scatterometers may be used to measure parameters such as Critical Dimension (CD) of developed photoresist or overlay error (OV) between two layers formed in or on a patterned substrate. The properties of the substrate may be determined by comparing the properties of the illumination beam before and after reflection or scattering of the beam by the substrate. Optical aberrations have been one of the major challenges of metrology tools used for photolithographic fabrication services for nanoscale devices. Many options for dealing with aberrations are often accompanied by high cost and incompatibility due to size requirements. Disclosure of Invention Therefore, it is desirable to reduce aberrations in high-precision inspection tools. Features disclosed herein may be used to mitigate aberrations in a cost-effective manner using optical parts that fit small volume constraints. In some aspects, an inspection apparatus includes a radiation source, a wedge system, an optical device, and a detector. The radiation source is configured to generate radiation. The wedge system includes a first wedge, a second wedge, and a radiation curable adhesive disposed between the first wedge and the second wedge