# US 8,570,516 B2 · Infrared direct illumination machine vision technique for semiconductor processing equipment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,516 B2 - Document ID: US8570516B2 - Status: Granted - Kind: B2 - Application number: 12/977,229 - Filed: 2010-12-23 - Published: 2011-06-30 - Granted: 2013-10-29 - Earliest claimed: 2008-09-12 - Assignees: Cognex Corporation - Applicants: Gang Liu; Lei Wang - Inventors: Gang Liu; Lei Wang - Web page: https://patentgrep.com/patent/US8570516B2 ## CPC - G03F 9/00: Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically (G03F7/22 takes precedence; preparation of photographic masks G03F1/00; within photographic printing apparatus for making copies G03B27/00) - G03F 9/7065: {Production of alignment light, e.g. light source, control of coherence, polarization, pulse length, wavelength} - G03F 9/7084: {Position of mark on substrate, i.e. position in (x, y, z) of mark, e.g. buried or resist covered mark, mark on rearside, at the substrate edge, in the circuit area, latent image mark, marks in plural levels} - G03F 9/7088: {Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection} - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract A vision system is provided to determine a positional relationship between a semiconductor wafer on a platen and an element on a processing machine, such as a printing screen, on a remote side of the semiconductor wafer from the platen. A source directs infrared light through an aperture in the platen to illuminate the semiconductor wafer and cast a shadow onto the element adjacent an edge of the semiconductor wafer. A video camera produces an image using light received from the platen aperture, wherein some of that received light was reflected by the wafer. The edge of the semiconductor wafer in the image is well defined by a dark/light transition. ## Claims ### Claim 1 A vision system for determining a positional relationship between a semiconductor wafer and an element for processing the semiconductor wafer, wherein the semiconductor wafer is on a platen that has an aperture there through and the element is located on a remote side of the semiconductor wafer from the platen, said vision system comprising: a source of infrared light, for directing a beam of infrared light through the aperture in the platen at an acute angle to a line that is perpendicular to a surface of the semiconductor wafer to illuminate the semiconductor wafer to cast a shadow onto the element adjacent an edge of the semiconductor wafer; and a camera for electrically acquiring an image of reflected incident infrared light, wherein at least some of the reflected infrared light was reflected by the semiconductor wafer. ### Claim 2 (depends on 1) The vision system as recited in claim 1 wherein the source produces a collimated light beam. ### Claim 3 (depends on 1) The vision system as recited in claim 1 wherein the source produces infrared light having a wavelength between 700 nm and 1000 nm. ### Claim 4 (depends on 1) The vision system as recited in claim 1 wherein the source produces infrared light having a wavelength that is either 740 nm or 870 nm. ### Claim 5 (depends on 1) The vision system as recited in claim 1 further comprising a filter located between the semiconductor wafer and the camera, wherein the filter is transparent to the infrared light. ### Claim 6 (depends on 1) The vision system as recited in claim 1 further comprising a window of material that is transparent to the infrared light and that is located in the aperture in the platen. ### Claim 7 (depends on 1) The vision system as recited in claim 1 wherein walls of the aperture in the platen have an anti-reflective material thereon. ### Claim 8 A vision system for determining a positional relationship between a semiconductor wafer and an element for processing the semiconductor wafer, wherein the semiconductor wafer is on a platen that has an aperture there through and the element is located on a remote side of the semiconductor wafer from the platen, said vision system comprising: a source which emits an infrared light beam that is directed at an acute angle to a line that is perpendicular to a surface of the semiconductor wafer, thereby illuminating the semiconductor wafer to cast a shadow onto the element adjacent an edge of the semiconductor wafer; and a camera for producing electrically an image from infrared light received from the aperture in the platen, wherein the edge of the semiconductor wafer is defined in the image by a dark/light transition. ### Claim 9 (depends on 8) The vision system as recited in claim 8 wherein the source produces infrared light having a wavelength between 700 nm and 1000 nm. ### Claim 10 (depends on 8) The vision system as recited in claim 8 wherein the source produces infrared light having a wavelength that is either 740 nm or 870 nm. ### Claim 11 (depends on 8) The vision system as recited in claim 8 wherein walls of the aperture in the platen have an anti-reflective material thereon. ### Claim 12 (depends on 8) The vision system as recited in claim 8 further comprising a filter located between the platen and the camera, wherein the filter is transparent to the infrared light. ### Claim 13 (depends on 8) The vision system as recited in claim 8 wherein the infrared light beam is collimated. ### Claim 14 A method for determining a positional relationship between a semiconductor wafer on a platen and an element for processing the semiconductor wafer that is on a remote side of the semiconductor wafer from the platen, said method comprising: emitting infrared light from a source; directing the infrared light through an aperture in the platen to illuminate the semiconductor wafer, wherein the infrared light is directed at an acute angle to a line that is perpendicular to a surface of the semiconductor wafer; thereby illuminating the semiconductor wafer to cast a shadow onto the element adjacent an edge of the semiconductor wafer; and employing a camera to produce electrically an image from infrared light received from the aperture in the platen, wherein at least some of that received infrared light has been reflected by the semiconductor wafer. ### Claim 15 (depends on 14) The method as recited in claim 14 wherein the infrared light has a wavelength between 700 nm and 1000 nm. ### Claim 16 (depends on 14) The method as recited in claim 14 wherein the infrared light has a wavelength that is either 740 nm or 870 nm. ### Claim 17 (depends on 14) The method as recited in claim 14 further comprising providing a filter which blocks non-infrared light from entering the camera. ### Claim 18 (depends on 14) The method as recited in claim 14 further comprising covering walls of the aperture in the platen with an anti-reflective material. ### Claim 19 (depends on 14) The vision system as recited in claim 14 wherein emitting infrared light from a source produces a collimated light beam.