View source for Specific Process Knowledge/Thin film deposition/Furnace LPCVD PolySilicon/Boron doped poly-Si and a-Si

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==Boron-doped amorphous silicon by using 4" LPCVD polysilicon furnace (B4) ==
''Result from Thomas Pedersen, DTU Nanotech (now DTU Nanolab), September 2015''
====Process parameters====

'''Pressure:'''  250 mtorr

'''Temperature:''' 580 °C

'''Silane (SiH<sub>4</sub>) flow:''' Constant at 80 sccm

'''Diborane (B<sub>2</sub>H<sub>6</sub>) flow:''' Varied from 3 sccm to 40 sccm

'''Anneal:''' No annealing afterwards

'''Test wafer position:''' Center of the boat

====Results====

The Boron concentration of the film was controlled by the flow of B<sub>2</sub>H<sub>6</sub> gas. To establish how boron doping concentration varied with B<sub>2</sub>H<sub>6</sub> flow, films of silicon were deposited with B<sub>2</sub>H<sub>6</sub> gas flows modulated during deposition to produce doping spikes. The two figures below show a typical SIMS concentration depth profile of a B<sub>2</sub>H<sub>6</sub> modulation-doped film deposited on a Silicon dioxide substrate. During deposition, the gas flow of SiH<sub>4</sub> was held constant, while flows of B<sub>2</sub>H<sub>6</sub> was varied to create the dopant spikes. 
 

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[[image:Boron_concentration.jpg|627x424px|left|thumb|Boron concentration measured by SIMS. Result from Thomas Pedersen, Nanotech, Sep 2015.]]


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[[image:Boron concentration2.jpg|627x424px|left|thumb|Boron concentration measured by SIMS. Result from Thomas Pedersen, Nanotech, Sep 2015.]]

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== Boron-doped amorphous silicon by using 4" LPCVD polysilicon furnace (B4) ==
''Result from Trine Holm Christensen, @Space, Feb. 2015''

====Process parameters====
The test was made on a n-type silicon wafer (100) with a 110 nm grown thermal oxide)

'''Pressure:'''  250 mtorr

'''Temperature:''' 580 °C

'''Silane (SiH<sub>4</sub>) flow:''' 80 sccm

'''Diborane (B<sub>2</sub>H<sub>6</sub>) flow:''' 7 sccm

'''Time:''' 75 min

'''Anneal:''' @950°C for 60 min in N<sub>2</sub>

'''Test wafer position:''' Center of the boat

A better uniformity of the resistivity across the wafer was achieved by subsequently annealing in N<sub>2</sub>, the annealing was done in Anneal Oxide Furnace (C1). The measured film thickness was 370 nm and the sheet resistance was measured to 200 &Omega;/sq +/- 15 &Omega;/sq.