Determination of customized components for fitting wafer profile

Patent metadata

Field	Value
Publication number	US-2016305772-A1
Application number	US-201615099346-A
Country	US
Kind code	A1
Filing date	Apr 14, 2016
Priority date	Apr 17, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

Method and system for defining basis functions for fitting distortions of profiles of objects in a batch, that has undergone a fabrication process, in a manner adaptable to the fabrication process to reduce the errors between profiles approximated with the use of such basis functions and actual object profiles. Process-specific individual basis functions are defined based on spatially-dense measurement of objects from training sub-set of the batch and applying learning algorithm to results of such measurement. Advantages of process-adaptable basis functions over generic basis functions for fitting distortion shapes of objects include higher accuracy of fitting either at larger or a fewer locations across the object.

First claim

What is claimed:

1 . A method for determining spatial profiles of objects from a set of objects, the method comprising:
with a shape-profiling tool and for each object from a first subset of objects in said set, measuring a corresponding spatial profile at M spatial locations across said object from the first subset
i) to determine a measured spatial profile, and
ii) to define a pre-determined number of basis spatial functions a combination of which approximates the measured spatial profile of each of the objects from the first set;
with the shape-profiling tool and for each object from a second subset of objects in said set, gauging a corresponding spatial profile at a pre-determined number m of spatial locations across the object from the second set to define profile data; and defining an approximated profile for each of objects in the second subset by fitting said profile data with a linear combination of said basis spatial functions.

2 . A method according to claim 1 , wherein the gauging includes gauging a corresponding in-surface profile at m spatial locations, wherein m<M.

3 . A method according to claim 2 , wherein said measuring and said gauging includes using optical sensors, and wherein the objects from the set include wafers.

4 . A method according to claim 1 , further comprising defining a number M such that
a dimensional deviation between the approximated profile and the measured in-surface profile of an object from said second subset set does not exceed the pre-determined value.

5 . A method according to claim 1 , further comprising defining the first and second subsets as complementary subsets.

6 . A method according to claim 1 , wherein each of said measuring and said defining includes determining in-plane distortions of wafers that have been identified for processing in a lithographic exposure tool.

7 . A method according to claim 1 ,
wherein said measuring a corresponding spatial profile at M spatial locations across the object from the first subset includes measuring said profile with a set of M optical sensors, one sensor per location, and wherein gauging a corresponding spatial profile at m<M spatial locations across the object from the second set includes measuring said profile with a set of m optical sensors, one sensor per location.

8 . A method according to claim 1 , further comprising affixing to one another first and second objects approximated profiles of which have been defined.

9 . A method according to claim 8 , wherein said first and second objects include semiconductor wafers and said affixing includes bonding the first wafer and the second wafer in a substrate bonding apparatus.

10 . A method for determining spatial profiles of objects, the method comprising:
with a shape-profiling tool and for each object from a first subset of the objects, measuring a corresponding spatial profile with M sensors of the tool to define a pre-determined number of basis spatial functions a combination of which approximates a measured spatial profile of each of the objects from the first subset; and defining an approximated spatial profile for each of objects in the second subset of the objects by fitting profile data, obtained from a measurement of each of the objects in the second subset with m sensors, with a combination of the pre-determined basis spatial functions.

11 . A method according to claim 10 , wherein objects include semiconductor wafers.

12 . A method according to claim 11 , further comprising affixing to one another first and second objects, approximated spatial profiles of which have been defined, in a substrate bonding apparatus.

13 . A method according to claim 10 , wherein said measuring includes measuring a corresponding in-plane profile of a semiconductor wafer.

14 . A method according to claim 10 , wherein said defining an approximated spatial profile includes defining an approximated in-plane profile of a semiconductor wafer.

15 . A method according to claim 10 , wherein said defining includes measuring each of the objects in the second subset with m sensors, wherein m<M.

16 . A method according to claim 10 , wherein at least one of said measuring a corresponding spatial profile and said defining an approximated spatial profile include includes simultaneously measuring an object with multiple sensors.

17 . A method according to claim 10 , wherein each of said measuring and defining includes determining in-plane distortions of wafers that have been identified for processing in a lithographic exposure tool.

18 . A method according to claim 10 , wherein said measuring and defining are effectuated for at least two batches of objects, each batch having been fabricated independently from another batch, and wherein basis spatial functions that have been defined based on measuring a first subset of objects of one batch differs from basis spatial functions that have been defined based on measuring a first subset of objects in another batch.

19 . A method for determining spatial profiles of objects, the method comprising:
determining an approximated spatial profile for each of the objects by fitting profile data, obtained from a simultaneous optical measurement of one subset of the objects at M locations across each object, with a set of basis functions that have been defined from a simultaneous optical measurement of another subset of the objects at m locations across each object.

20 . A method according to claim 19 , further including defining the set of basis functions from the simultaneous optical measurement of another subset of the objects at M locations across each object, wherein m<M.

21 . A method for determining spatial profiles of precision workpieces from a set of precision workpieces produced in the same precision process, the method comprising:
a) with a shape-profiling tool and for each precision workpiece from a first subset of said set, measuring a corresponding shape at M spatial locations across said precision workpiece to determine measured shapes of the precisions workpieces in the first subset; b) using a numerical analysis technique to define customized basis spatial functions from the measured shapes of the precision workpieces in the first subset, said customized basis spatial functions defined such that a combination thereof approximates each of said measured shapes; c) with the shape-profiling tool and for each precision workpiece from a second subset of said set, measuring a corresponding shape at m spatial locations across the precision workpiece to define measured shapes of the precision workpieces in the second subset; d) defining an approximated shape for each of the precision workpieces in the second subset by fitting said measured shapes of the precision workpieces in the second subset with a linear combination of the customized basis spatial functions.

22 . A method according to claim 21 , wherein the using includes employing a matrix eigendecomposition technique configured to determines the customized basis functions numerically.

23 . A method according to claim 21 , wherein the using includes employing a statistical screening of data representing the measured shapes of the precisions workpieces in the first set, said statistical screening forming output data, said output data defining the customize basis spatial functions.

24 . A method according to claim 21 , wherein the measuring a corresponding shape at M spatial

Assignees

• Nikon Corp

Inventors

• Bow Travis D
• Pang Henry
• Hashemi Fardad A

Classifications

• G01B11/24 Primary

  for measuring contours or curvatures · CPC title

• G03F7/7055

  Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption · CPC title

• G03F9/7003

  Alignment type or strategy, e.g. leveling, global alignment · CPC title

• G03F7/70783

  Handling stress or warp of chucks, masks or workpieces, e.g. to compensate for imaging errors or considerations related to warpage of masks or workpieces due to their own weight · CPC title

• G01B2210/56

  Measuring geometric parameters of semiconductor structures, e.g. profile, critical dimensions or trench depth · CPC title