Thermally compensated shadow mask

A method for making an improved high temperature shadow mask assembly for a large diameter silicon wafer, comprising the steps of:

• forming a planar plate having a pattern of apertures misregistered at room temperature but registered at high temperature during a deposition process, each of those respective distances from the centroid of said plate at room temperature is misregistered with respect to the corresponding desired distance from the centroid of said wafer of a corresponding shadow image on the silicon wafer at room temperature, by approximately the product of the difference between said high temperature and said room temperature times said desired distance times the difference between the thermal coefficient of expansion of the plate material and the thermal coefficient of expansion of the silicon wafer;
• clamping said plate and said wafer with their said centroids mutually coincident, in a fixture which does not maintain their said centroids mutually coincident at said high temperature;
• raising the temperature of said plate and silicon wafer to said high temperature for processing;
• whereby the differential expansion of the plate material will bring the apertures therein into a minimum total misalignment with the intended deposition locations on the silicon wafer.