Method and apparatus using interferometric metrology for high aspect ratio inspection
First Claim
1. An interferometric inspection system for inspecting a semiconductor sample, the system comprising:
- at least one illumination source to generate an illumination beam;
an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and directing the test beam reflected from the sample and the reference beam reflected from the mirror to generate an interference image;
an image sensor for receiving the interference image generated by the inteferometric microscope module; and
an alignment module located in the optical path between the interferometric microscope module and the image sensor for adjusting at least one of the orientation and position of the interference image relative to the image sensor.
1 Assignment
0 Petitions
Accused Products
Abstract
In one embodiment, the present invention provides an interferometric inspection system for inspecting semiconductor samples. The system includes at least one illumination source for generating an illumination beam and an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam directed to a tilted reference mirror. The beams are combined to generate an interference image at an image sensor. The tilted reference mirror is tilted at a non-normal angle with respect to the reference beam that is incident on the mirror to thereby generate fringes in the interference image. The system also includes an image sensor for acquiring the interference image from the interferometric microscope module and generates an inherence signal. The system further includes a processing module configured to generate complex field information corresponding to the sample from the interference image signal and an alignment module located in the optical path between the interferometric module and the image sensor. In another embodiment, the processing module is configured to generate complex field information from either spatial fringe analysis or temporal fringe analysis performed on the interference image signal.
77 Citations
55 Claims
-
1. An interferometric inspection system for inspecting a semiconductor sample, the system comprising:
-
at least one illumination source to generate an illumination beam; an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and directing the test beam reflected from the sample and the reference beam reflected from the mirror to generate an interference image; an image sensor for receiving the interference image generated by the inteferometric microscope module; and an alignment module located in the optical path between the interferometric microscope module and the image sensor for adjusting at least one of the orientation and position of the interference image relative to the image sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. An interferometric inspection system for inspecting a semiconductor sample, the system comprising:
-
at least one illumination source to generate an illumination beam; an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and directing the test beam reflected from the sample and the reference beam reflected from the mirror to generate an interference image; an image sensor for receiving the interference image generated by the inteferometric microscope module; and an adjustable magnification module located in the optical path between the interferometric microscope module and the image sensor for adjusting the size of the interference image onto the image sensor. - View Dependent Claims (12, 13)
-
-
14. A interferometric inspection system for inspecting a semiconductor sample, the system comprising:
-
at least one illumination source for generating a coherent illumination beam and an incoherent illumination beam; an interferometric microscope module configured to split the coherent illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a first reference mirror, and to direct the test beam reflected from the sample and the reference beam reflected from the first reference mirror to generate an interference image and to split the incoherent beam into a test beam directed to the semiconductor sample and a reference beam towards the first reference mirror, and to generate an interference image for topographic measurement, wherein the topographic measurement comprises determining an image of a sample at a selected axial position of the test beam axis relative to the surface of the sample; a switching mechanism for switching the operation of the inspection system between interferometric inspection and topographic measurement; and an image sensor for acquiring the interference image from the inteferometric microscope module and generating an interference image signal. - View Dependent Claims (15, 16, 17, 18, 19)
-
-
20. An interferometric inspection system for inspecting semiconductor samples, the system comprising:
-
at least one illumination source to generate an illumination beam; an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and combining into a combined beam the test beam reflected from the sample and the reference beam reflected from the reference mirror, the combined beam forming an interference image, wherein the reference mirror is tilted at a non-normal angle with respect to the incident reference beam to generate fringes in the interference image; an image sensor for receiving the interference image from the inteferometric microscope module and generating an interference image signal from the interference image; an alignment mechanism located in the optical path between the interferometric microscope module and the image sensor to provide adjustment between the interference image and the image sensor; and a processing module configured to generate complex field information corresponding to the semiconductor sample from the interference image signal. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 46)
-
-
38. An interferometric inspection system for inspecting semiconductor samples, the system comprising:
-
at least one illumination source to generate an illumination beam; an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and combining into a combined beam the test beam reflected from the sample and the reference beam reflected from the reference mirror, the combined beam forming an interference image; a switching mechanism for switching the operation of the inspection system between interferometric measurement and topographic measurement an image sensor for acquiring the interference image from the inteferometric microscope module and generating an interference image signal; and a processing module configured to generate from the interference image signal one of topographic measurements and complex field information corresponding to the semiconductor sample, wherein the switching mechanism comprises a dichroic surface located in the optical path between the interferometric microscope module and the reference mirror for reflecting a portion of the incident reference beam back along the path of the incident reference beam to the interferometric microscope module to perform the topographic measurement. - View Dependent Claims (39)
-
-
40. An interferometric inspection system for inspecting semiconductor samples, the system comprising:
-
at least one illumination source to generate an illumination beam; an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and combining into a combined beam the test beam reflected from the sample and the reference beam reflected from the reference mirror, the combined beam forming an interference image; a switching mechanism for switching the operation of the inspection system between interferometric measurement and topographic measurement an image sensor for acquiring the interference image from the inteferometric microscope module and generating an interference image signal; and a processing module configured to generate from the interference image signal one of topographic measurements and complex field information corresponding to the semiconductor sample, wherein the switching mechanism comprises a shutter located between the at least one illumination source and the interferometric microscope module.
-
-
41. An interferometric inspection system for inspecting semiconductor samples, the system comprising:
-
at least one illumination source to generate an illumination beam; an interferometric microscope module for splitting the illumination beam into a test beam directed to the semiconductor sample and a reference beam towards a reference mirror, and combining into a combined beam the test beam reflected from the sample and the reference beam reflected from the reference mirror, the combined beam used to generate an interference image; a switching mechanism for switching the operation of the inspection system between interferometric measurement and topographic measurement, wherein the topographic measurement comprises determining an image of a sample at a selected axial position of the test beam axis relative to the surface of the sample; an adjustable magnification module to provide fine adjustment of the size of the interference image onto the image sensor; an alignment mechanism located in the optical path between the interferometric microscope module and the image sensor to provide adjustment between the interference image and the image sensor by compare a location of a feature in the interference image with a location of a similar feature in a stored image to generate an alignment signal to determine the misalignment between the interference image and the stored images; an image sensor for acquiring the interference image from the inteferometric microscope module and generating an interference image signal; and a processing module configured to generate from the interference image signal one of topographic measurements and complex field information corresponding to the semiconductor sample, wherein the complex field information corresponding to the sample is generated from one of spatial fringe analysis and temporal fringe analysis performed on the fringes of the interference image signal.
-
-
42. A method for inspecting a wafer using interferometric techniques, the method comprising:
-
a) combining a test wave reflected from a first portion of a wafer and a reference wave reflected from a reference mirror to produce on an image sensor an interference optical image, b) reconstructing complex field information for the first portion from the interference optical image; c) generating a first signal representation of the first portion of the wafer using reconstructed complex field information; d) comparing the first signal representation to a second signal representation of a wafer to generate a resultant signal representation, wherein the resultant signal representation is used to identify defects in the first portion of the wafer; and e) identifying and comparing a feature in the interference image with a location of a similar feature in a stored image to determine the misalignment between the interference image and the stored image and to generate an alignment signal. - View Dependent Claims (43, 44, 45, 47, 48, 49, 50, 51, 52, 53, 54, 55)
-
Specification