GB1374617A - Grinding machine and method and semiconductor formed thereby - Google Patents

Abstract

1374617 Grinding SONY CORP 21 Dec 1971 [21 Dec 1970] 59374/71 Heading B3D A machine for grinding a predetermined edge contour on a workpiece, such as a semiconductor wafer 1, Fig. 3, having a round portion la and a straight portion 1a<SP>1</SP>, comprises a chuck 17 for holding a workpiece, means to rotate the chuck, and a grinding head 15 comprising a plurality of resilient grinding devices 60 attached thereto, each of the devices having an oblique grinding surface facing the chuck. The machine is used to profile the edges of the wafer to the shape shown in Fig. 5 to compensate for the non-uniform growth on the edge of the wafer when an epitaxial layer is vapour-deposited over the surface of the wafer. The machine has a frame 6, Fig. 6, formed with an oil pan 7 connected by columns 9 to a panel 8. A plate 10 which performs a circular translatory movement is supported by supports 26 which are eccentrically mounted in rotatable mechanisms 20 driven by gearing 22, 42 from a motor 43. The eccentricity of the supports is variable from zero to a maximum. The plate 10 carries two rows of holding means 11 each consisting of an air or hydraulic cylinder 12 and a holder 13. The piston of the cylinder is connected to a rod 14 for movement up-anddown, the rod being prevented from rotating. The lower end of each rod is connected to a respective grinding device 15, each device consisting of a plurality of resilient strips 60, Fig. 13, for example, stainless steel. The strips are secured by screws 64 to a head 57 on the rod 14 and are bent outwardly at their lower ends 62. The ends 62 have a curved cross-section with electro-deposited abrasive on their lower surfaces. The degree of resiliency of the strips can be varied by vertical adjustment of a ring 65. Grinding fluid is supplied to the strips through a connector 71 and tube 58. Each grinding head is disposed above a vacuum chuck for holding a wafer 1, each chuck having a head 17 provided with a number of concentric grooves 17A, Fig. 12, and radial grooves in its upper surface connected by holes 17c and a chamber 17b. The head is carried at the upper end of a hollow shaft 47 which communicates with the chamber 17b and with a fiting 55 connected to a vacuum line. The shafts 47 of the vacuum chucks are mounted in bearings 45 in the oil pan 7 and rotated by gearing 49, 53. The wafers are loaded into the machine on a magazine 73 when the rods 14 are raised, the magazine having a plurality of recessed apertures for positioning the wafers 1 above the vacuum chuck when the magazine is supported on hydraulically-operated elevators 19 which can be lowered so that the magazine is lowered leaving the wafers on the chucks so as to be held thereon by the vacuum. The wafers are rotated by the chucks, and the plate 10, and hence the grinding devices 15, moved with a circular translatory movement by the mechanism 20 so that the abrasive coated strips 62 form the desired profile on the edges of the wafers 1.