Voltage adjustment method of load sensor

Abstract

Provided is a voltage adjustment method for a load sensor, which uses the load sensor to appropriately measure a load. The voltage adjustment unit (9) is adjusted (first to third adjustment steps) sothat the voltage values calculated by the measurer (8) are the same even when a load is applied to the vicinity of any of the first sensor (71), the second sensor (72), and the third sensor (73) on the chuck table (2). Furthermore, in the repeating step, the first to third adjustment steps are repeated. When the sensors (71-73) are subjected to a predetermined load, that is, when the sensors (71-73) are subjected to a predetermined load near the sensors (71-73) on the chuck table (2), the total voltage calculated by the measurer (8) can be equalized, and thus, the measured value of the load inthe measurer (8) can be equalized.

Description

technical field [0001] The invention relates to a voltage adjustment method of a load sensor. Background technique [0002] In order to strengthen the bending strength of the wafer, for example, grinding marks formed on the wafer by grinding with a grinding wheel are removed by a grinding process with a grinding pad. Polishing is performed by pressing a polishing pad against a wafer with a predetermined load. That is, the grinding removal amount changes according to the magnitude of the load. By performing grinding with the same load in a plurality of grinding devices, the amount of grinding removal can be made the same. [0003] For example, as disclosed in Patent Document 1, the load received by the wafer from the polishing pad is detected as follows. Load sensors made of piezoelectric elements are arranged at vertices of an equilateral triangle whose center of gravity is the center of the chuck table. The total value of the loads measured by these three load sensors i...

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Problems solved by technology

However, it is difficult to pressurize the three load cells equally

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