초록 ▼

Apparatus and method for reading an identification mark on a semi-conductor wafer. The wafer includes a marking area which bears a relief mark. The marking area is illuminated by a segmented light source and is viewed by a viewing device. The viewing device sees a dark segment and an adjacent lighte

Apparatus and method for reading an identification mark on a semi-conductor wafer. The wafer includes a marking area which bears a relief mark. The marking area is illuminated by a segmented light source and is viewed by a viewing device. The viewing device sees a dark segment and an adjacent lighted segment which preferably surrounds the dark segment, and the mark appears as a light image in the dark segment. Preferably the segmented light source is a diffuse light source with an opaque patch at its center. The method is particularly effective for reading soft marks with low profiles.

대표청구항 ▼

[ What is claimed is:] [1.] Apparatus for viewing a relief mark on a semi-conductor wafer having a principal plane, the relief mark forming part of a target area comprising(a) reflective flat surfaces which are parallel to the principal plane, and(b) reflective relief surfaces which form the relief

[ What is claimed is:] [1.] Apparatus for viewing a relief mark on a semi-conductor wafer having a principal plane, the relief mark forming part of a target area comprising(a) reflective flat surfaces which are parallel to the principal plane, and(b) reflective relief surfaces which form the relief mark and which are inclined to the principal plane, the boundaries of the relief surfaces defining a marking area, d apparatus comprising(1) a wafer location in which a said wafer can be supported with the target area in a viewing position;(2) a segmented light source for illuminating the target area of said wafer; and(3) a device location in which a viewing device can be placed for viewing the target area of a said wafer with its target area in the viewing position; apparatus being such that, when(i) the segmented light source is on,(ii) a said wafer is supported in the wafer location with its target area in the viewing position,(iii) a viewing device is placed in the device location and is viewing the target area along a viewing axis, and(iv) any part of the apparatus or wafer which is shaped so that the viewing device does not see all the light reflected from areas adjacent to the target area has been modified so that the light segment is fully reflected into the viewing device, viewing device(a) views the target area and the segmented light source along a viewing axis and sees the segmented light source as (a) a relatively dark segment which covers the mark and (b) an adjacent light segment, and(b) views the mark as a light image on a dark background, the image being formed by light which has been reflected from relief surfaces of the mark; d apparatus having at least one of the following characteristics:(A1) the area of the light segment is at least 0.7 times the area of the dark segment;(A2) around at least 30% of the periphery of the dark segment, the width of the light segment is at least 0.8 times the width of the dark segment;(A3) the radial dimension of the light segment is greater than the radial dimension of the dark segment in at least one plane containing the viewing axis;(B) the light from the light segment has a maximum intensity and a minimum intensity, and the maximum intensity is not more than twice the minimum intensity;(C) at least 30% of the periphery of the marking area is separated from the periphery of the dark segment by a distance which is not more than 2 times the minimum dimension of the marking area; and(D) at least 30% of the light from the light segment which strikes the marking area is light which is at an angle of e.degree. to f.degree. to a perpendicular to the principal plane of the wafer, where e is within the range 0.8.degree. to 3.degree., and f is within the range 3.degree. to 9.degree. and is at least (e+1).degree..