Etch stops and alignment marks for bonded wafers

摘要

There is described a method of making a bonded wafer (54) by diffusing regions of the first major surface of a first wafer. Trenches (30) are etched a predetermined distance into the first wafer from the first major surface toward a second major surface (32). The first major surface and trenches (30) are coated with oxide (34). The first major surface of the first wafer is bonded to a second wafer (50) to form a bonded wafer (54). The second major surface of the bonded wafer (54) which is also the second major surface (32) of the first wafer is ablated (not shown) until oxide (34) in the trenches (30) is detected. The bonded wafer (54) is cut into chips which are packaged as integrated circuits.