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US 12,752,390 B2Granted
Optical thickness control during a chemical mechanical polishing process and apparatus for effecting the same
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorChun-Hsi Huang
Life of this patent
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Abstract
A substrate may be loaded onto a chemical mechanical polishing (CMP) apparatus, which includes a polishing pad and a wafer carrier that holds the substrate. The wafer carrier includes a backside plate, a wafer carrier frame, and at least one optical vertical displacement measurement unit that includes a respective laser source and a respective pixelated image sensor. A total reflection geometry is used to reflect a laser beam off a top surface of the backside plate. A polish rate or a polish thickness of a polished portion of the substrate may be measured at each location underneath at least one reflection point during the CMP process.
Claims20
A chemical mechanical polishing (CMP) method, comprising:
- loading a substrate onto a chemical mechanical polishing (CMP) apparatus, wherein the CMP apparatus comprises a polishing pad located on a top surface of a platen, a wafer carrier that holds the substrate, and a process controller configured to control operation of components within the wafer carrier, wherein the wafer carrier comprises a backside plate configured to press the substrate on a top surface of the polishing pad, a wafer carrier frame that holds the backside plate with a cavity between a top surface of the backside plate and an inner surface of the wafer carrier frame, a plurality of downforce adjustment elements located at different radial distances from a vertical axis passing through a geometrical center of the substrate, a plurality of optical vertical displacement measurement units that includes a respective laser source configured to emit an incident laser beam onto the top surface of the backside plate at an angle of incidence that induces total reflection at a respective reflection point located at different radial distances from the vertical axis passing through the geometrical center of the substrate;
- and
- polishing a bottom surface portion of the substrate by applying downforce to the backside plate while the substrate contacts a top surface of the polishing pad and while the platen rotates,
- wherein the plurality of downforce adjustment elements includes a respective pixelated image sensor configured to detect a pixel location of a respective reflected laser beam derived from the incident laser beam by total reflection at the respective reflection point.
1 more element
A chemical mechanical polishing (CMP) apparatus, comprising:
- a polishing pad located on a top surface of a platen;
- a wafer carrier that holds a substrate and facing the polishing pad;
- a process controller configured with processor-executable instructions to control operation of components within the wafer carrier,
- wherein the wafer carrier comprises:
- a backside plate configured to press the substrate on a top surface of the polishing pad;
- a wafer carrier frame that holds the backside plate with a cavity between a top surface of the backside plate and an inner surface of the wafer carrier frame;
- and
- at least one optical vertical displacement measurement unit that includes a respective laser source configured to emit an incident laser beam onto the top surface of the backside plate at an angle of incidence that induces total reflection at a respective reflection point,
- wherein the at least one optical vertical displacement measurement unit includes at least one optical vertical displacement measurement unit includes a respective pixelated image sensor configured to detect a pixel location of a respective reflected laser beam derived from the incident laser beam by total reflection at the respective reflection point.
6 more elements
A chemical mechanical polishing (CMP) method, comprising:
- loading a substrate onto a chemical mechanical polishing (CMP) apparatus, wherein the CMP apparatus comprises a polishing pad located on a top surface of a platen and a wafer carrier that holds the substrate, wherein the wafer carrier comprises a backside plate configured to press the substrate on a top surface of the polishing pad, a wafer carrier frame that holds the backside plate with a cavity between a top surface of the backside plate and an inner surface of the wafer carrier frame, and at least one optical vertical displacement measurement unit that includes a respective laser source configured to emit an incident laser beam onto the top surface of the backside plate at an angle of incidence that induces total reflection at a respective reflection point;
- and
- polishing a bottom surface portion of the substrate by applying downforce to the backside plate while the substrate contacts the top surface of the polishing pad and while the platen rotates,
- wherein the at least one optical vertical displacement measurement unit includes a respective pixelated image sensor configured to detect a pixel location of a respective reflected laser beam derived from the incident laser beam by total reflection at the respective reflection point.
1 more element
Dependencies are inferred from the claim text.