Charged Particle Beam Processing System with Visual and Infrared Imaging
First Claim
1. A charged particle beam system for processing a substrate, comprising:
- a charged particle column, configured to produce a beam of charged particles which can be focused on the surface of the substrate;
an in-vacuum optical subsystem, configured to collect scattered infrared radiation and visible light from the surface and regions near the surface of the substrate;
a precision stage, configured to transport the substrate alternately between a location under the in-vacuum optical subsystem and a location under the charged particle column;
an illumination subsystem, configured to provide infrared radiation and visible light to the surface of the substrate; and
an imaging subsystem, configured to focus the scattered infrared radiation and visible light collected by the in-vacuum optical subsystem onto one or more detectors.
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Abstract
A charged particle beam system for processing substrates is disclosed, comprising a charged particle column, combination infrared radiation and visible light illumination and imaging subsystems, in-vacuum optics, and a precision stage for supporting and positioning the substrate alternately under the charged particle column and the imaging system. The axes of the charged particle column and imaging system are offset to enable much closer working distances for both imaging and beam processing than would be possible in a single integrated assembly. A method for extremely accurately calibrating the offset between the column and imaging system is disclosed, enabling beam processing at precisely-determined locations on the substrate. The imaging system is capable of locating sub-surface features on the substrate which cannot be seen using the charged particle beam. Two illumination modes are disclosed, enabling both bright-field and dark-field imaging in infrared radiation and visible light.
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Citations
16 Claims
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1. A charged particle beam system for processing a substrate, comprising:
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a charged particle column, configured to produce a beam of charged particles which can be focused on the surface of the substrate; an in-vacuum optical subsystem, configured to collect scattered infrared radiation and visible light from the surface and regions near the surface of the substrate; a precision stage, configured to transport the substrate alternately between a location under the in-vacuum optical subsystem and a location under the charged particle column; an illumination subsystem, configured to provide infrared radiation and visible light to the surface of the substrate; and an imaging subsystem, configured to focus the scattered infrared radiation and visible light collected by the in-vacuum optical subsystem onto one or more detectors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method for calibrating the distance between the axis of an optical imaging subsystem and the axis of a charged particle column, comprising the steps of:
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configuring a charged particle column to produce a focused charged particle beam on a substrate surface; configuring an optical imaging system to form an image of the substrate surface; configuring a stage to transport the substrate alternately between a location under the optical imaging subsystem and a location under the charged particle column; mounting the charged particle column and the optical imaging system with a fixed relative offset distance; positioning the substrate using the stage initially under the imaging system and centering an expendable feature on the axis of the imaging subsystem; transporting the substrate to a location under the charged particle column, where the transport distance corresponds to the expected offset between the imaging subsystem and the charged particle column; forming a first structure on the substrate using charged particle beam processing; transporting the substrate to a location under the imaging subsystem, where the transport distance is exactly opposite to the expected offset between the imaging subsystem and the charged particle column; imaging the first structure formed by charged particle beam processing and determining the offset of the first structure with respect to the expendable feature, wherein the offset corresponds to the difference between the actual and the expected offset between the imaging subsystem and the charged particle column; transporting the substrate to a location under the charged particle column, wherein the transport distance is calibrated using the offset just determined, thereby enabling the stage to position the expendable feature much more precisely under the charged particle column; forming a second structure on the substrate using charged particle beam processing; transporting the substrate to a location under the imaging subsystem, where the transport distance is exactly opposite to the calibrated offset between the imaging subsystem and the charged particle column; imaging the second structure formed by charged particle beam processing, thereby verifying the accuracy of the offset calibration; transporting the substrate to a location under the charged particle column, wherein the transport distance is modified by the offset between a critical feature to be processed and the expendable feature, thereby positioning the critical feature directly under the charged particle column; and forming a third structure on the substrate using charged particle beam processing, wherein the third structure has the required size, shape for the desired processing, and wherein the third structure is directly above the critical feature. - View Dependent Claims (16)
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Specification