| 摘要 |
PURPOSE:To obtain a highly reliable and economical semiconductor device by providing, as the protection film of P-N junction of a semiconductor chip, a silicon dioxide thin film to a first layer, a polysilicon thin film to a second layer and a silicon nitride thin film to a third layer. CONSTITUTION:A silicon dioxide film 13 is formed to both surfaces of an N type silicon substrate 11. Next, the silicon dioxide film 13 is removed by the fluoric acid by the photo etching method from the notches 16 provided for separating the P-N junction forming area and chip. The substrate is placed within a mixed gas of monosilane, boron trichloride and H2 and a polysilicon film 14 including positive impurity is formed on the surface where said processing is carried out. Next, the polysilicon film 14 is left to the region where is larger than the P-N junction forming area but is smaller than the notches 16 and unwanted polysilicon film is removed by the photo etching method using the mixed etchant of nitric acid plus fluoric acid. Heat processing is then carried out and thereby a positive impurity included in the polysilicon film 14 diffused to the silicon substrate 11 and a positive region 12 is formed, obtaining required electrical characteristic. Next, a silicon nitride thin film 17 is formed on the surface having completed said processing. |
