Minimal force air bearing for lapping tool
View Patent ↗A lapping tool for lapping a wafer section in a well controlled manner, has a head with an actuator for bending the row tool, and a force multiplier coupled between the actuator and row tool to multiply the force generated by the actuator for application of greater bending force to the row tool than can be generated by the actuator. Furthermore, at least two actuators, which are controlled together, simultaneously apply force to one force multiplier, so as to further increase bending force. The increase in available force permits the use of a row tool of a ceramic or other material that is substantially stiffer than stainless steel, such as a row tool having a coefficient of thermal expansion that is substantially similar to that of the rowbar itself. The tool further includes structures for tilting or otherwise orienting the wafer section relative to the lapping plate.
1. A lapping tool for lapping a substrate section, comprising
a row tool having a substrate section mounted thereto,
a lapping plate,
a head to which the row tool is mounted,
a fluid bearing for supporting the row tool to position the substrate section upon the lapping plate, and
a control system controlling the fluid bearing to maintain the fluid bearing in contact with the lapping plate at a near zero normal force.
2. The lapping tool of claim 1 wherein the fluid bearing comprises a supply of fluid and a housing having an fluid inlet coupled to said supply.
3. The lapping tool of claim 2 wherein the fluid bearing is of a conductive material, the control system measuring electrical connectivity between said fluid bearing and said lapping plate, and controlling the supply of fluid to create an electrical connectivity at a value corresponding to the desired normal force of said fluid bearing.
4. The lapping tool of claim 1 wherein the fluid bearing further comprises a porous media within the housing and having a first surface adjacent to said inlet and a second exposed surface adjacent to the lapping plate, such that fluid from the fluid supply flows through the porous media.