| 摘要 |
PURPOSE:To simplify a manufacturing process while reducing pollution and damage, and to increase dielectric strength easily by masking a P type conduction region or an N type conduction region with an oxide film with a window, forming a different conduction region in the conduction region through the window and forming a wide shallow diffusion layer while spreading the window of the oxide film in succession. CONSTITUTION:When the surface of the N type conduction region 1 of a wafer is masked with the oxide film 5 such as a silicon film to which the window 4 is bored, said oxide film 5 is coated previously with a coating film 6 difficult to be eroded by a fluoric acid solution. The wafer is placed in an impurity gas atmosphere, and the deep P type conduction region 2 is formed through heating and diffusion for a fixed time through the window 4. The wafer is immersed in the fluoric acid solution, and the oxide film 5 of the peripheral section of the window 4 is removed. the peripheral section of the window 4 is removed by the intruding fluoric acid solution. The wafer is diffused for a fixed time in an impurity gas again. Accordingly, a P type conduction region 2, which is shallower than the last time but wider than that, is formed. Operation removing the peripheral suction of the window 4 and a process of impurity diffusion are repeated. Consequently, dielectric streugth generated by a PN junction increases. |
