Rotating head ellipsometer
AssigneeTherma-Wave, Inc.
InventorBarry R. Bowman
Life of this patent
Estimating the term…
Abstract
An ellipsometric apparatus provides a rotating focused probe beam directed to impinge a sample in any direction. A rotating stage rotates the wafer into a linear travel range defined by a single linear axis of a single linear stage. As a result, an entire wafer is accessed for measurement with the single linear stage having a travel range of only half the wafer diameter. The reduced single linear travel results in a small travel envelope occupied by the wafer and consequently in a small footprint of the apparatus. The use of a rotating probe beam permits measurement of periodic structures along a preferred direction while permitting the use of a single reduced motion stage.
Claims40
A system for evaluating a sample with a probe beam comprising:
- an optical assembly for directing and focusing said probe beam on said sample at a predetermined angle of incidence so that said beam is reflected therefrom;
- and
- a motor coupled to the optical assembly for rotating the optical assembly with respect to the sample such that a plane defining the incident and specularly reflected beam is rotated thereby varying the direction in which the probe beam impinges upon the sample.
A system for evaluating a sample with a probe beam directed to reflect off the sample, with the incident beam and a specularly reflected beam defining a beam plane, said system comprising:
- means for rotating the beam plane to vary the direction in which the incident probe beam strikes the sample;
- and
- a processor for controlling the rotation means so that various areas on the sample can be measured.
An ellipsometer sub-system comprising:
- a first stage for supporting a wafer;
- a plate rotatably mounted above the first stage, said plate carrying focusing optics for directing and focusing a probe beam towards the wafer at a non-normal angle, said plate further carrying collection optics for collecting the probe beam after being reflected from the wafer;
- and
- a motor for rotating the plate with respect to the first stage for changing the direction in which the probe beam strikes the sample.
A method of evaluating a sample comprising the steps of:
- generating a probe beam of light;
- directing the probe beam to the sample so that it is reflected therefrom;
- and
- rotating the direction of incidence of the probe beam so that measurements can be made on the sample from different directions.
A method of inspecting a sample with a probe beam which is directed via at least one optical element to reflect off the sample, said sample resting on a movable stage, said method comprising the steps of comprising:
- adjusting the position of the sample with respect to the probe beam to measure at a desired location and with a particular direction of incidence of the probe beam, said adjusting step being implemented by performing one or more of the following steps:
- rotating the sample with respect to the probe beam using the movable stage;
- linearly translating the sample with respect to the probe beam using the movable stage;
- and
- rotating the optical element in order to change the direction of incidence of the probe beam on the sample.
A system for evaluating a sample with a polychromatic probe beam comprising:
- first optics for directing the probe beam to reflect off the sample;
- second optics for collecting the reflected probe beam;
- an optical plate for supporting said first and second optics;
- means for measuring the reflected probe beam and generating output signals as a function of wavelength;
- a motor coupled to the optics plate for rotating the optics plate with respect to the sample such that the direction of the incidence of the probe beam on the sample can be varied;
- and
- a processor for evaluating the sample based on the generated output signals.
An ellipsometer for evaluating a sample by measuring the change in polarization state of probe beam induced upon reflection from the sample comprising:
- a first stage for supporting a wafer;
- first optics for directing the probe beam to reflect off the sample;
- second optics for collecting the reflected probe beam;
- a rotatable optical plate for supporting said first and second optics;
- a motor for rotating the plate with respect to the first stage for changing the direction in which the probe beam strikes the sample;
- means for measuring the change in polarization state of the reflected probe beam and generating output signals in response thereto;
- and
- a processor for evaluating the sample based on the generated output signals.
The ellipsometer 34, wherein said first stage is a rotatable stage.
Dependencies are inferred from the claim text.