The Polysilicon-Silicon Interface

1987 ◽  
Vol 106 ◽  
Author(s):  
Robert W. Keyes
Keyword(s):  
Single Crystal ◽  
Polycrystalline Silicon ◽  
Single Crystal Silicon ◽  
Modern Method ◽  
High Gain ◽  
Bipolar Transistors ◽  
Crystal Silicon ◽  
Silicon Technology ◽  
Silicon Interface ◽  
Dopant Source

ABSTRACTPolycrystalline silicon is frequently deposited on single crystal silicon as a part of devices. The poly is used as both a dopant source and a low resistance contact in a modern method of fabricating high gain bipolar transistors. The randomness of polysilicon and its interface with the single crystal is an inherent source of differences among nominally identical transistors, however, and is a marked departure from the trend towards more and more perfect crystals that characterizes the rest of silicon technology.

Electrical Properties of Polycrystalline-Silicon Thin Films for VLSI

1986 ◽  
Vol 71 ◽  
Author(s):  
T I Kamins
Keyword(s):  
Electrical Properties ◽  
Integrated Circuits ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Polycrystalline Silicon ◽  
Crystalline Silicon ◽  
Single Crystal Silicon ◽  
Active Regions ◽  
Crystal Silicon ◽  
Polysilicon Film

AbstractThe electrical properties of polycrystalline silicon differ from those of single-crystal silicon because of the effect of grain boundaries. At low and moderate dopant concentrations, dopant segregation to and carrier trapping at grain boundaries reduces the conductivity of polysilicon markedly compared to that of similarly doped single-crystal silicon. Because the properties of moderately doped polysilicon are limited by grain boundaries, modifying the carrier traps at the grain boundaries by introducing hydrogen to saturate dangling bonds improves the conductivity of polysilicon and allows fabrication of moderate-quality transistors with their active regions in the polycrystalline films. Removing the grain boundaries by melting and recrystallization allows fabrication of high-quality transistors. When polysilicon is used as an interconnecting layer in integrated circuits, its limited conductivity can degrade circuit performance. At high dopant concentrations, the active carrier concentration is limited by the solid solubility of the dopant species in crystalline silicon. The current through oxide grown on polysilicon can be markedly higher than that on oxide of similar thickness grown on singlecrystal silicon because the rough surface of a polysilicon film enhances the local electric field in oxide thermally grown on it. Consequently, the structure must be controlled to obtain reproducible conduction through the oxide. The differences in the behavior of polysilicon and single-crystal silicon and the limited electrical conductivity in polysilicon are having a greater impact on integrated circuits as the feature size decreases and the number of devices on a chip increases in the VLSI era.

Growth Mechanism of Hydrogen Clusters

1997 ◽  
Vol 467 ◽  
Author(s):  
N. H. Nickel ◽  
G. B. Anderson ◽  
N. M. Johnson ◽  
J. Walker
Keyword(s):  
Fermi Level ◽  
Single Crystal ◽  
Growth Mechanism ◽  
Polycrystalline Silicon ◽  
Single Crystal Silicon ◽  
Surface Region ◽  
Crystal Silicon ◽  
Hydrogen Clusters ◽  
Near Surface ◽  
Crystallographic Planes

ABSTRACTIt is demonstrated that the exposure of polycrystalline silicon (poly-Si) to monatomic hydrogen results in the formation of H clusters. These H stabilized platelets appear in the near-surface region ( 100 nm) and are predominantly oriented along {111} crystallographic planes. Platelet concentrations of ≈5×1015, 1.5×1016-cm−3, and 2.4×1017 cm−3 were observed in nominally undoped poly-Si, phosphorous doped poly-Si (P=1017 cm−3), and phosphorous doped single crystal silicon (P>3×1018 cm−3), respectively. Results obtained on doped c-Si demonstrate that platelet generation occurs only at Fermi-level positions of Ec -EF < 0.4 eV.

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