Improved Yield on Bipolar Device Products
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
This article defines the optimum oxygen precipitation range to provide minimum device leakage characteristics for bipolar devices. The optimum oxygen precipitation range for maximum leakage limited yield is 9-15 PPMA. Below 9 PPMA, the amount of oxygen precipitation is insufficient to getter impurities found in device processing. Above 15 PPMA, the excessive precipitation weakens the silicon lattice, making the wafer susceptible to plastic deformation (warpage) and associated slip. The following table shows the effects of oxygen precipitation on electrical test yield. (Image Omitted) The oxygen precipitation size and density also affect leakage limited yield. For optimum yields, a small but dense precipitation morphology is required.