Patent ID: 7815489

Claim:
A method for the simultaneous double-side grinding of a plurality of semiconductor wafers during which the wafer thickness is decreased, wherein each semiconductor wafer lies such that it is freely moveable in a cutout of one of a plurality of carriers caused to rotate by means of a rolling apparatus and is thereby moved on a cycloidal trajectory, wherein the semiconductor wafers are machined in material-removing fashion between two rotating working disks, wherein each working disk comprises a working layer containing bonded abrasive, wherein the magnitude of the ratio of the difference in the magnitudes of the theoretical wear (r) of the two working layers to the mean value of the magnitudes of the wear of the two working layers for each radial position r is less than 1/1000, wherein the magnitude of the theoretical wear of each working layer is given by ℜ i ⁡ ( r ) =  ∫ e min e max ⁢ a 2 ⁢ σ i 2 + e 2 ⁢ ω i 2 + ( r 2 - a 2 - e 2 ) ⁢ σ i ⁢ ω i σ i - ω i 2 ⁢ 2 ⁢ ( a 2 ⁢ r 2 + e 2 ⁢ r 2 + a 2 ⁢ e 2 ) - r 4 - a 4 - e 4 ( σ i - ω i 2 · a 2 - e 2 r ⁢ 2 + σ i + ω i 2 ) · l ⁡ ( e ) · ⅆ e  . where α indicates the pitch radius of the circulating movement of the carriers on the working disks about the midpoint of the rolling apparatus; e indicates the distance between the currently considered reference point and the midpoint of the corresponding carrier; l(e) indicates the arc length—running within the area of the semiconductor wafer—of the circle with radius e about the midpoint of the corresponding carrier; r indicates the radial position with respect to the midpoint of the working disks; σ i indicates the angular velocity of the circulation of the carriers about the midpoint of the working disks; ω i indicates the angular angular velocity of the inherent rotation of the carriers about their respective midpoints, e min =max{0; e ecc −R} and e max =e ecc +R where R=radius of the semiconductor wafer denote the lower and upper limits of the integration over e; e ecc indicates the eccentricity of the semiconductor wafer in the carrier and the index i=o for the upper working disk or i=u for the lower working disk indicates whether the angular velocities σ i and ω i relate to the upper or the lower working disk.