| 摘要 |
PURPOSE: To obtain a semiconductor device in which initial trimming of resistance is effected by depositing silicon oxide on silicon nitride while specifying the thickness thereof and then irradiating the silicon oxide with a laser beam. CONSTITUTION: At first, the thickness of silicon oxide 9 is selected between (2/3+2n)/4×λ/1.41 and (4/3+2n)/4×λ/1.41, where λ is the wavelength of irradiation laser beam 20 and (n) is an arbitrary integer larger than 0. When the laser 20 impinges on the silicon oxide 9 through the upper atmosphere, the laser beam 20 is reflected 21, 22, respectively, on the silicon oxide 9 and the interface between the silicon oxide 9 and a silicon nitride 8. But since the wavelength of the laser beam 20 and the thickness of silicon oxide 9 are selected, the sum of the intensity of the reflected lights 21, 22 becomes 0 because of the phase difference and the laser beam 20 is utilized entirely for trimming a thin film resistor 5. Consequently, deficiency of laser power can be prevented at the time of trimming. |
