Inspection method and apparatus and lithographic processing cell

• US 8,887,107 B2
• Filed: 08/09/2013
• Issued: 11/11/2014
• Est. Priority Date: 09/06/2012
• Status: Expired

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Mos, Everhardus Cornelis, Simons, Hubertus Johannes Gertrudus, Ten Berge, Peter, Schoumans, Nicole, Kubis, Michael, Aben, Paul Cornelis Hubertus
• Primary Examiner(s): Siek, Vuthe
• Assistant Examiner(s): Ngo, Brian
• Application Number:
  US13/963,947
• Publication Number:
  US 20140089870A1
• Time in Patent Office: 459 Days
• Field of Search: 716/51, 716/52, 716/53, 716/54
• US Class Current: 716/54
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• 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 7/70525 Controlling normal operating mode, e.g. matching different apparatus, remote control or prediction of failure
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• 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

A method of calculating process corrections for a lithographic tool, and associated apparatuses. The method comprises measuring process defect data on a substrate that has been previously exposed using the lithographic tool; fitting a process signature model to the measured process defect data, so as to obtain a model of the process signature for the lithographic tool; and using the process signature model to calculate the process corrections for the lithographic tool.

Claims

1. A method of calculating a process correction for a lithographic tool comprising:

measuring process data on a substrate that has been previously exposed using the lithographic tool;

fitting, by a processing unit, a process signature model to the measured process data, so as to obtain a fitted process signature model for the lithographic tool; and

calculating, by the processing unit directly after the fitting, the process correction for the lithographic tool for any location on the substrate based on the fitted process signature model using all possible relevant degrees of freedom of the lithographic tool.

2. The method of claim 1 wherein the process data comprises data describing a deviation from ideal of a position of a layer relative to a preceding layer.

3. The method of claim 2 wherein the process signature model is a Zernike function comprising radial and tangential overlay components.

4. The method of claim 1 further comprising applying the calculated process correction for each exposed field in a subsequent exposure using the lithographic tool.

5. The method of claim 4, further comprising:

repeating the measuring, fitting, calculating, and applying prior to exposure of each substrate lot to obtain an updated process correction.

6. The method of claim 1 wherein the process signature model comprises over ten parameters.

7. The method of claim 1 wherein the calculating further comprises interpolating and extrapolating the fitted process signature model to determine the process correction.

8. The method of claim 1 wherein the measuring comprises performing fewer than 500 measurements on the substrate.

9. The method of claim 8 wherein the measuring comprises performing fewer than 200 measurements on the substrate.

10. An inspection apparatus comprising:

a projection system configured to project a radiation beam onto a substrate that has been previously exposed using a lithographic tool;

a detector configured to detect scattered radiation having interacted with the substrate; and

a processor configured to;

measure process data from the detected scattered radiation;

fit a process signature model to the measured process data, so as to obtain a fitted process signature model for the lithographic tool; and

calculate, directly after fitting the process signature model, a process correction for the lithographic tool for any location on the substrate based on the fitted process signature model using all possible relevant degrees of freedom of the lithographic too.

11. The inspection apparatus of claim 10 wherein the process data comprises data describing a deviation from ideal of a position of a layer relative to a preceding layer.

12. The inspection apparatus of claim 11 wherein the process signature model is a Zernike function comprising radial and tangential overlay components.

13. The inspection apparatus of claim 10 wherein the process signature model comprises over ten parameters.

14. The inspection apparatus of claim 10 wherein the processor uses all possible relevant degrees of freedom of the inspection apparatus to calculate the process correction.

15. The inspection apparatus of claim 10 wherein the processor calculates the process correction using interpolation and extrapolation of the fitted process signature model.

16. The inspection apparatus of claim 10, wherein the processor is further configured to calculate the process correction directly after obtaining the fitted process signature model.

17. An apparatus comprising:

a projection system configured to project a radiation beam onto an exposed substrate;

a detector configured to detect the radiation beam after reflection from the substrate; and

a processor configured to;

measure process data from the reflected radiation beam;

fit a process signature model to the measured process data to obtain a fitted process signature model for a lithographic tool used to expose the substrate; and

calculate, directly after fitting the process signature model, a process correction for the lithographic tool for any location on the substrate based on the fitted process signature model using all possible relevant degrees of freedom of the lithographic tool.

18. The apparatus of claim 17, wherein:

the radiation beam comprises a plurality of radiation beams,

the detector is configured to detect the plurality of radiation beams after reflection from the substrate as a plurality of measurements,

the process correction comprises a plurality of process corrections per field of the substrate, and

the process signature model comprises a plurality parameters, the plurality of measurements being, less than the plurality of process corrections.