Back then, chip designers considered it risky to add two or three layers of metal on top of the silicon wafer because each new layer added hills and valleys that made it difficult to keep photolithographic patterns in focus.
Back then, chip designers considered it risky to add two or three layers of metal on top of the silicon wafer because each new layer added hills and valleys that made it difficult to keep photolithographic patterns in focus.
当时的晶片设计者认为在矽晶圆上加上两三层金属有点冒险，会使晶圆表面凹凸不平，增加光刻过程中聚焦的困难。