SELECTIVE-AREA DEPOSITION OF DIAMOND ON 4 IN SI WAFERS

The deposition of diamond by different techniques on Si wafers of up t o 8 in diameter has been reported by various groups. The uniformity of these blanket coatings is indicated to be of the order of +/- 10%. Th e commonly-used method of enhancing nucleation by scratching is not re commended for Si wafers, especially for selective-area diamond deposit ion. The selective area deposition of diamond on 4 in Si wafers has be come possible by use of the standard lift-off technique as practised i n ordinary microelectronic processing. The pretreatment is applied aft er masking on the free Si-substrate surface. A photoresist film is dep osited either on Si wafers or on Si3N4 and/or SiO2 precoated (>1000 An gstrom) Si wafers by spin-coating, using a mask to obtain the desired pattern. Following a special pretreatment step of the selectively mask ed wafer surface, the photoresist is dissolved in acetone, then diamon d is deposited. The diamond coating can be formed with or without boro n doping. By this technique, thermistors and other sensor devices have been developed.