| 摘要 |
PURPOSE:To obtain the semiconductor pressure sensor in which a gauge rate of a distortion sensing element part is increased and unevenness of resistance values is sufficiently reduced by presetting a peak of concentration of said element part in a surface region of a substrate. CONSTITUTION:A wafer of N type {110} plane direction as a substrate is subjected to a thermal oxidation in an oxide atmosphere at 1,100-1,150 deg.C to grow a thermal SiO2 film 4 on the surface. A window is formed in the diffusion gauge forming region part which will become a distortion sensing element part 2 by photoring and boron as a P type impurity is diffused from that window part by thermal diffusion. As a diffusion source, BBr3, BN and etc. are used and a diffusion gauge is formed under the temperature condition of 960-985 deg.C. After completion, the wafer is taken out from the furnace and an oxide film left on a surface of the diffusion layer, for example, a B2O3 film is removed. An SiO2 layer 3 is grown over the whole surface of wafer by gas-phase growth and it is subjected to annealing in an inert atmosphere at 950-1,000 deg.C for about 30min. |
