New method for estimation of grain boundaries contribution to resistance of highly doped polysilicon

The authors propose a new method for estimation of the contribution of the grain boundaries (GB) to the total resistance of highly doped polysilicon r esistors. The method is based on the technique known as "current trimming". The resistance of the polysilicon resistor and its temperature coefficient is measured before and after application of current pulses: on the basis o f obtained changes in those parameters the share of the resistance attribut ed to the grain boundaries as well as the temperature coefficient of grain boundaries' resistance are deduced. The experiments were carried out on the resistors patterned in the 625 degrees C LPCVD polysilicon doped by ion im plantation of Boron and annealed at 1050 degrees C for 30 min in a dry oxyg en atmosphere. The properties were estimated in the doping range from 1 x 1 0(25) to 1.2 x 10(26) m(-3). The method can be extended to other polycrysta lline materials.