with multiple substrate batch processing this process is economical to deposit both undoped and doped silicon layers undoped silicon can be deposited using silane disilane silicon tetrachloride silicon trichloride silicon dichloride and the like the exact crystallographic nature of the silicon deposited depends upon the temperature of deposition for example at low deposition temperatures of about 600 u00b0 650 u00b0 c the silicon deposited is mostly amorphous at somewhat higher temperatures of about 650 u00b0 690 u00b0 c a mixture of amorphous and polysilicon will be obtained at higher temperatures of about 690 u00b0 750 u00b0 c the deposited silicon will be mostly polycrystalline silicon doped silicon layers can also be produced by cvd but generally at lower rates of deposition further the prior art lpcvd deposition processes performed in the apparatus of fig1 and 2 produce films of nonuniform thickness the feed gases are adjusted to admix an appropriate amount of dopant gas in addition to the silicon precursor gas for example small amounts of phosphine can be added to produce phosphorus doped silicon and small amounts of arsine can be added to produce arsenic doped silicon the present process provides greatly increased deposition rates for doped silicon layers which are more uniform in thickness than the prior art layers the present process will be further described by reference to fig3 fig3 illustrates a single wafer reactor 31 in which either doped or undoped silicon layers.