Test site aided new IC product introduction

The introduction of a 32-kb bipolar RAM using an unclamped complementary transistor switch memory cell is described. Key features of the process technology are the polysilicon-base NPN transistor and trench isolation. Both the cell layout and processing are optimized with an exploratory test site in the early manufacturing cycle. The exploratory test site has yield test structures with different ground rules and cell layouts side by side. The yield detractors and product yields are continuously monitored in the manufacturing line with a product test site in order to enhance defect learning. The product test site is stepped into the product wafer and has the same ground rules as the product. The test-site-aided product introduction doubled the defect learning rate