KR-20260066159-A - OPTICAL METROLOGY WITH INFLUENCE MAP OF UNKNOWN SECTION

KR20260066159AKR 20260066159 AKR20260066159 AKR 20260066159AKR-20260066159-A

Abstract

Optical measurements of a sample containing a structure of interest (SOI) optically coupled to a section having an unknown structure are performed using an influence map of deviation contributions from the unknown structure. The influence map is generated by acquiring measurement data for multiple locations containing the SOI and the unknown structure, and determining the deviation contribution at each location by separating the deviation contribution from the basis contribution from the SOI and the unknown structure. During the measurement of a location, the deviation contribution associated with that location can be obtained from the influence map and removed from the measured data. One or more parameters of the SOI can be determined by fitting the processed data to a model including a strict model for the SOI and an effective model for the basis contribution of the unknown structure.

Inventors

류, 이량
리, 융
왕, 양
스, 징성

Assignees

온투 이노베이션 아이엔씨.

Dates

Publication Date: 20260512
Application Date: 20221122
Priority Date: 20211124

Claims (14)

A method for generating a model for optical measurements of a structure-of-interest (SOI) on a sample, wherein the method comprises: A step of acquiring measurement data from different locations on the sample - each of the different locations on the sample comprises an SOI having a known structure and a section having an unknown structure that varies across the different locations, and the measurement data acquired from each of the different locations comprises a first basis contribution from the SOI having a known structure, a second basis contribution from the section having an unknown structure, and a deviation contribution from the section having an unknown structure, wherein the deviation contribution from the section having an unknown structure varies for each of the different locations - ; A step of obtaining an influence map for the sample including deviation contributions associated with each of the above different locations; and A step of generating a model for optical measurement of the SOI using the measurement data obtained from the different locations and the influence maps above - the model includes a strict model representing the SOI and an effective model representing the second basis contribution from the section having the unknown structure without the deviation contribution - A method including
In claim 1, the step of generating the model for optical measurement of the SOI is: A step of removing the deviation contribution from the measurement data obtained from each of the different locations to generate processed measurement data comprising a combination of the first basis contribution from the SOI and the second basis contribution from the section having the unknown structure without the deviation contribution; and Step of developing the model based on the above-mentioned processed measurement data A method including
A method according to claim 1, wherein the different locations are within a region of interest (ROI), and the deviation contribution from the section having the unknown structure varies across the ROI.
In paragraph 3, the method wherein the ROI is located within a die on a wafer.
In paragraph 3, the method wherein the ROI consists of one or more measurement sites from a plurality of dies across a wafer.
A method according to claim 1, wherein the section having the unknown structure is located in an area below the SOI, above the SOI, or next to the SOI.
A method according to claim 1, wherein the measurement data comprises at least one of elliptical measurement data, reflection measurement data, interference measurement data, Fourier transform infrared spectroscopy (FTIR) data, or a combination thereof.
As a system for generating a model for optical measurements of a structure-of-interest (SOI) on a sample, Means for acquiring measurement data from different locations on the sample above - each of the different locations on the sample comprises an SOI having a known structure and a section having an unknown structure that varies across the different locations, and the measurement data acquired from each of the different locations comprises a first basis contribution from the SOI having the known structure, a second basis contribution from the section having the unknown structure, and a deviation contribution from the section having the unknown structure, wherein the deviation contribution from the section having the unknown structure varies for each of the different locations - ; Means for obtaining an influence map for the sample including deviation contributions associated with each of the above different locations; and Means for generating the model for optical measurement of the SOI using the measurement data obtained from the different locations and the influence map, wherein the model comprises a strict model representing the SOI and an effective model representing the second basis contribution from the section having the unknown structure without the deviation contribution. A system including
In paragraph 8, the means for generating the model for optical measurement of the SOI is: Means for generating processed measurement data comprising a combination of the first basis contribution from the SOI and the second basis contribution from the section having the unknown structure without the deviation contribution, by removing the deviation contribution from the measurement data obtained from each of the different locations; and Means for developing the above model based on the above processed measurement data A system including
In claim 8, the system wherein the different locations are within a region of interest (ROI) and the deviation contribution from the section having the unknown structure varies across the ROI.
In Clause 10, the above ROI is a system located within a die on a wafer.
In claim 10, the system wherein the ROI comprises one or more measurement sites from a plurality of dies across a wafer.
In paragraph 8, the system in which the section having the unknown structure exists in an area below, above, or next to the SOI.
A system according to claim 8, wherein the measurement data comprises at least one of elliptical measurement data, reflection measurement data, interference measurement data, Fourier transform infrared spectroscopy (FTIR) data, or a combination thereof.

Description

Optical Metrology with Influence Map of Unknown Section Cross-reference regarding related applications This application claims priority under 35 USC §119 to U.S. Provisional Application No. 63/283,201, filed November 24, 2021, titled "OPTICAL METROLOGY WITH INFLUENCE MAP OF UNKNOWN SECTION," the entirety of which is incorporated herein by reference. Technology field The subject matter described herein generally relates to optical measurement, and in particular to modeling and measuring structures including unknown sections. The semiconductor and other similar industries typically use optical metrology equipment to provide non-contact evaluation of samples during processing. In optical metrology, the sample under test is illuminated, for example, by light of a single wavelength or multiple wavelengths. After interaction with the sample, the generated light is detected and analyzed to determine one or more characteristics of the sample. The analysis typically involves a model of the structure under test. The model can be generated based on the structure's material and nominal parameters (e.g., film thickness, line and space width, etc.). One or more parameters of the model may vary, and predicted data can be calculated for each parameter variation based on the model, for example, using Rational Coupled Wave Analysis (RCWA) or other similar techniques. Measured data can be compared with the predicted data for each parameter variation, for example, in a non-linear regression process, until a good fit is achieved between the predicted data and the measured data, at which point the fitted parameter is determined to accurately represent the parameters of the structure under test. Modeling techniques are particularly useful when a sample has a periodic structure. Unfortunately, when a sample contains non-periodic sections, analytically modeling the sample can be difficult. Furthermore, if a sample contains one or more sections with unknown designs and/or characteristics—that is, if preliminary structural information regarding one or more sections is unknown or unavailable—it is not possible to construct a rigorous model of the sample. Therefore, an improved optical metrology process that can be used to measure sample structures containing unknown and/or non-periodic sections is desirable. Optical measurements of a sample containing a structure of interest (SOI) optically coupled to a section having an unknown structure are performed using an influence map of deviation contributions from the unknown structure. The influence map is generated by acquiring measurement data from multiple locations containing the SOI and the unknown structure, and determining the deviation contribution at each location by separating the deviation contribution from the basis contribution from the SOI and the unknown structure. During the measurement of a location, the deviation contribution associated with that location can be retrieved from the influence map and removed from the measured data. One or more parameters of the SOI can be determined by fitting the processed data to a model including a strict model for the SOI and an effective model for the basis contribution of the unknown structure. In one embodiment, a method for generating an influence map for optical measurement of a sample comprises the step of acquiring measurement data from a plurality of locations, wherein the measurement data acquired from each location is a combination of a first basis contribution from a structure of interest (SOI) having a known structure, a second basis contribution from a section having an unknown structure, and a deviation contribution from the section having the unknown structure. The method comprises the step of determining the deviation contribution from the section having the unknown structure for each location based on the measurement data from the plurality of locations. The method further comprises the step of generating the influence map of the section having the unknown structure by storing the deviation contribution and the associated location for each of the plurality of locations. In one embodiment, a system for generating an effect map for optical measurement of a sample comprises means for acquiring measurement data from a plurality of locations, wherein the measurement data acquired from each location is a combination of a first basis contribution from a structure of interest (SOI) having a known structure, a second basis contribution from a section having an unknown structure, and a deviation contribution from the section having the unknown structure. The system further comprises means for determining the deviation contribution from the section having the unknown structure for each location based on the measurement data from the plurality of locations. The system further comprises means for generating the effect map of the section having the unknown structure by storing the deviation contribution and the associated location for