Metrology hardware specification using a hardware simulator
AssigneeTimbre Technologies, Inc.
InventorsJunwei Bao, Nickhil Jakatdar
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Abstract
A method and system in metrology for integrated circuits, for incorporating the effects of small metrology hardware-based and material-based parameter variations into a library of simulated diffraction spectra. In a first embodiment, a method is disclosed for determining metrology hardware specification ranges that correspond to specified CD measurement accuracy. In a second embodiment, a method for modifying a library of simulated diffraction spectra for optimization to the particular parameters of a specific piece of metrology hardware and specific material batches is disclosed.
Claims27
A method in integrated circuit metrology for adapting a library of metrology signals for use with different metrology systems, each of the metrology systems comprising a metrology hardware device with associated metrology hardware device parameters and a sample including a sample material with associated material parameters, the method comprising:
- specifying ranges for system parameters of a selected ideal metrology system, the system parameters comprising metrology hardware device parameters and material parameters;
- verifying that a first metrology system has system parameters within the specified system parameter ranges of the ideal metrology system;
- adapting a library of metrology signals functionally operative with the ideal metrology system to be functionally operative with tile first metrology system;
- and
- using the library of metrology signals to obtain profile data of integrated circuit structures;
- wherein hardware device parameters include one or more of angle of metrology beam incidence, numerical aperture, wavelength range, polarization, and noise.
A method of revising a library of simulated metrology signals calculated using ideal system parameters of an ideal metrology system, so as to be optimized to actual system parameters for a first metrology system including a first metrology hardware device and a first sample material, the system parameters comprising metrology hardware device parameters and material parameters, comprising:
- a) calculating the change in a first simulated metrology signal S at each of multiple wavelength values as each of the system parameters is varied;
- b) evaluating the ratio between the variation in each of the system parameters and the change in the first simulated metrology signal at each of the multiple wavelength values;
- c) determining the actual system parameters for the first metrology system;
- d) determining the variation between the actual systems parameters and corresponding ideal system parameters;
- e) calculating a revised first simulated metrology signal corresponding to the ratios of steps a) and b) and the variation between the actual systems parameters and the ideal system parameters;
- and
- f) repeating steps a)-e) for instances of simulated metrology signals from the library.
An integrated circuit metrology system comprising:
- a metrology device comprising:
- a metrology beam source, the metrology beam source configured to direct a metrology beam at the integrated circuit structure, the integrated circuit structure having material parameters;
- and
- a beam receiver configured to receive and measure a metrology signal from the integrated circuit structure;
- a metrology profiler configured to compare metrology signal data from the metrology beam with profile data from a library of metrology signals, the library of metrology signals corresponding to an ideal metrology system having system parameters;
- and
- a metrology system adapter configured to adapt metrology data to be functionally operative with a plurality of metrology devices;
- wherein the metrology device, having system parameters including metrology hardware device parameters and material parameter is configured to have the system parameters within specified system parameter ranges of the system parameters of the ideal metrology system;
- and
- wherein the metrology profiler is configured to adapt the library of metrology signals to be functionally operative with the metrology device.
A computer-readable storage medium containing computer executable code to adapt a library of metrology signals, the library of metrology signals corresponding to an ideal metrology system having system parameters, to be functionally operative with a first metrology system having actual system parameters by instructing a computer to operate as follows:
- a) calculating the change in a first metrology signal from the library at multiple wavelength values as each of the system parameters is varied within a small range;
- b) evaluating the ratio between the variation in each of the system parameters and the change in the first metrology signal at the multiple wavelength values;
- c) determining the variation between actual system parameters of the first metrology system and corresponding system parameters of an ideal metrology system;
- d) calculating a revised first metrology signal corresponding to the ratios of steps a) and b) and the variation between the actual system parameters and the system parameters of the ideal metrology system;
- and
- e) repeating steps a)-d) for instances of metrology signals from the library.
A computer-readable storage medium containing stored data including a set of first simulated diffraction spectra corresponding to a set of first grating profiles measured by a first metrology system, and a set of second simulated diffraction spectra corresponding to the set of first grating profiles, the set of second simulated diffraction spectra being a modification of the set of first simulated diffraction spectra optimized to an actual system parameter vector of a second metrology system.
Dependencies are inferred from the claim text.