Mechanical stress of the electrical performance of polycrystalline-siliconresistors

Results are presented of a study on the mechanical stress dependence of the resistance of polycrystalline silicon (Poly-Si) films doped with different atomic species. Two types of Poly-Si film implanted with boron and phospho rus ions were studied, namely, B-doped films of 400 nm and P-doped films of 250 nm thickness, which were deposited by low-pressure chemical vapor depo sition at 620 degreesC on thermally oxidized silicon wafers. The film dopin g was done by ion implantation at 50 keV, with a dose of boron and phosphor us of 2x10(14) and 5.3x10(14) cm(-2), respectively. The Poly-Si films were annealed in a N-2 ambient at 1000 degreesC for 20 min to activate the impla nted atoms. A controlled amount of external stress was applied to the silic on wafers to study the impact on the electrical performance of the implante d Poly-Si resistors. The resistance of the B-doped Poly-Si films is shown t o increase by the mechanical stress, while the resistance of the P-implante d Poly-Si films remained unchanged. It is concluded that this difference is related to the structural differences between Poly-Si films implanted with boron and phosphorus, respectively.