Development of a Measuring Equipment for Silicon Wafer Warp

Abstract

Larger diameter wafers are used to decrease the cost of IC manufacturing and the wafer thickness is decreasing for form factor and thermal power dissipation considerations. The larger wafer requires a large scanning area to inspect the warp, and warp measurement of large and thin silicon wafers is greatly affected by the gravity-induced deflection. In this paper the gravity-induced deflection was calculated using finite element method by supporting the wafer horizontally with three steel balls. A laser displacement sensor based on triangulation principle was used to measure the warp and an air bearing stage was developed to achieve high straightness. The shape of the wafer was obtained using the silicon wafer warp measuring equipment.

Evaluation of polishing-induced subsurface damage based on residual stress distribution via measured global surface deformation for thinned silicon wafers

“…Therefore, the accurate relative positions of the three supports to the silicon wafer were fed back into the finite element model. The total deformation was measured by a laser displacement sensor (LK-H022K, Keyence, Japan) which was mounted on the granite guides which could move along the aerostatic guides driven by servo motors in the directions of x and y axes [26].…”