Low Noise Polycrystalline Semiconductor Resistors by Hydrogen Passivation.
DEPARTMENT OF THE AIR FORCE WASHINGTON DC
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The present invention is a process of fabricating low noise polycrystalline silicon resistors. This process includes steps to passivate the resistors to reduce the lf noise which is routinely observed in prior art devices. As mentioned above, most theories suggest that the lf noise originates in the interfaces where there are carrier traps. The process of the present invention includes a step to passivate these interfaces with hydrogen in a unique treatment which serves to demonstratably improve the lf noise characteristics of polysilicon resistors. The low noise crystalline silicon resistors are fabricated in the following sequence 1 deposit an appropriate thickness of ploysilicon film on an oxidized wafer, 2 resistor doping of the polysilicon film by ion implantation, 3 heavy doping of the end-contact regions of the polysilicon film by high-dose ion implantation, 4 patterning the polysilicon resistor, 5 oxidationannealing of the polysilicon resistor, 6 open contacts to the polysilicon resistor, 7 aluminum metallization to form ohmic contacts, 8 a long e.g. 3 hours low temperature e.g. at 375 C pure hydrogen annealing to passivate the interface states in ploysilicon resistors.
- Solid State Physics