MODEL-BASED SCANNER TUNING SYSTEMS AND METHODS

• US 20150045935A1
• Filed: 10/28/2014
• Published: 02/12/2015
• Est. Priority Date: 06/03/2008
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: CAO, Yu, SHAO, Wenjin, GOOSSENS, Ronaldus Johannes Gijsbertus, YE, Jun, KOONMEN, James Patrick
• Granted Patent: US 10,569,469 B2
• Time in Patent Office: Days
• US Class Current: 700/120
• CPC Class Codes: B29C 64/386 Data acquisition or data processing for additive manufacturing
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 7/70458 Mix-and-match, i.e. multiple exposures of the same area using a similar type of exposure apparatus, e.g. multiple exposures using a UV apparatus
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions
• CPC Class Codes: G03F 7/70516 Calibration of components of the microlithographic apparatus, e.g. light sources, addressable masks or detectors
• CPC Class Codes: G03F 7/70525 Controlling normal operating mode, e.g. matching different apparatus, remote control or prediction of failure
• CPC Class Codes: G06F 2113/18 Chip packaging
• CPC Class Codes: G06F 30/00 Computer-aided design [CAD]
• CPC Class Codes: G06F 30/20 Design optimisation, verification or simulation optimisation, verification or simulation of circuit designs G06F30/30
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36

Abstract

Systems and methods for tuning photolithographic processes are described. A model of a target scanner is maintained defining sensitivity of the target scanner with reference to a set of tunable parameters. A differential model represents deviations of the target scanner from the reference. The target scanner may be tuned based on the settings of the reference scanner and the differential model. Performance of a family of related scanners may be characterized relative to the performance of a reference scanner. Differential models may include information such as parametric offsets and other differences that may be used to simulate the difference in imaging behavior.

Claims

1. A computer-implemented method for adjusting imaging performance of a lithographic apparatus relative to an imaging performance of a reference lithographic apparatus, the method comprising:

maintaining a lithographic apparatus model characterizing imaging performance of the lithographic apparatus in terms of a set of tunable parameters;

generating a simulated wafer contour based on a design layout and a simulated lithographic process using an initial set of values of the set of tunable parameters;

comparing the simulated wafer contour with a reference wafer contour to generate a differential metric; and

adjusting the initial set of values of the set of tunable parameters until the differential metric has a desired value such that imaging performance of the lithographic apparatus is substantially close to the imaging performance of the reference lithographic apparatus,

wherein one or more of the above steps are implemented by the computer.

2. The method of claim 1, wherein the to-be-tuned lithographic apparatus belongs to a set of lithographic apparatuses, one of which is designated as the reference lithographic apparatus.

3. The method of claim 2, wherein the designation of the reference lithographic variation may change from one lithographic apparatus to another lithographic apparatus within the set of lithographic apparatuses.

4. The method of claim 1, wherein one or both of the lithographic apparatus and the reference lithographic apparatus are virtual scanners represented by respective apparatus models.

5. The method of claim 1, wherein the comparing step further comprises:

formulating a cost function that represents the differential metric; and

mathematically optimizing the cost function to obtain the desired value of the differential metric.

6. The method of claim 1, wherein the initial set of values of the set of tunable parameters is obtained by scanner metrology.

7. The method of claim 1, wherein the reference wafer contour is a measured wafer contour produced by the reference lithographic apparatus.

8. The method of claim 7, wherein the reference wafer contour is produced by a reference lithographic process.

9. The method of claim 7, wherein the reference wafer contour is produced by a reference design layout.

10. The method of claim 1, the differential metric is obtained using an Optical Proximity Correction (OPC) verification tool.

11. The method of claim 10, wherein hot spots identified by the OPC verification tool are added to update the design layout.

12. The method of claim 11, wherein the lithographic apparatus model is updated based on the updated design layout.

13. The method of claim 1, wherein the lithographic apparatus model comprises a differential model derived from a baseline model of the lithographic apparatus, the baseline model having parameters corresponding to parameters of a reference lithographic apparatus.

15. A computer program product comprising a non-transitory computer readable medium having instructions thereon to perform the method of claim 1 when executed by a computer.

14. The method of claim 14, wherein the differential model comprises differences in parametric values for one or more of:

design layout parameters, optical parameters, lithography process parameters.