Optical measuring system with illumination provided through a void in a collecting lens
OwnerAndrei Brunfeld, Gregory Toker +2inventors
InventorsAndrei Brunfeld, Gregory Toker, Bryan Clark, Morey T. Roscrow
Life of this patent
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Abstract
An optical measuring system includes a scatterometer in which an illumination beam is provided through an aperture in a lens used to collect light for the scattering detection. The void may be a slit in the lens, a missing portion along an edge of the lens, or another suitable void. Another detection channel may be provided to detect light returning through the void in the collecting lens, for example, a profilometer may be implemented by detecting interference between reflected light returning along the illumination path and light from the illumination source.
Claims34
An optical measurement system, comprising:
- an illumination subsystem for directing an illumination beam at a surface under inspection;
- a first optical subsystem for measuring a first characteristic of the surface under inspection, wherein the first optical subsystem includes a collecting lens for collecting light returned from the surface under inspection from the illumination beam and a first detector for detecting an intensity of the light collected by the collecting lens, wherein the collecting lens defines a void passing through the collecting lens and devoid of any lens material, and wherein the illumination subsystem directs the illumination system through the void passing through the collecting lens.
A method of performing optical measurements, comprising:
- directing an illumination beam at a surface under inspection through a void defined by and passing through a collecting lens of a first optical subsystem, wherein the void is devoid of any lens material of the collecting lens;
- measuring a first characteristic of the surface under inspection using the first optical subsystem by collecting light returned from the surface under inspection from the illumination beam using the collecting lens;
- and
- first detecting an intensity of the light collected by the collecting lens.
An optical inspection head, comprising:
- an illumination subsystem for directing an illumination beam at a surface under inspection;
- a first optical subsystem for measuring a first characteristic of the surface under inspection, wherein the first optical subsystem includes a collecting lens for collecting light returned from the surface under inspection from the illumination beam and a detector for detecting an intensity of the light collected by the collecting lens, wherein the collecting lens defines a void passing through the collecting lens and devoid of any lens material, and wherein the illumination subsystem directs the illumination system through the void passing through the collecting lens;
- and
- a profilometer for measuring a height of the surface under inspection, wherein light returned from the surface under inspection to the profilometer passes through the void in the collecting lens of the first optical subsystem.
Dependencies are inferred from the claim text.