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Boron Drive-in + Pre-dep furnace (A1)

A1 Boron Drive-in + Pre-dep furnace. Positioned in cleanroom 2

The Boron Drive-in + Pre-dep furnane (A1) is a Tempress horizontal furnace for oxidation of silicon wafers, annealing of the grown oxide, drive-in of boron after a pre-deposition and oxidation of the boron phase layer. Boron pre-deposition takes place in the same furnace. The Boron Drive-in furnace can also be used for drive-in of boron which has been ion implanted.

Boron source wafers are used as the doping source for the pre-dep process to dope Si wafers with boron to make conductive structues, etch stop layers etc. There are only a few source wafers, i.e. it is not possible to make an entire batch of 30 wafers, but both sides of the doping source wafers are available for pre-deposition. It is necessary to activate the source wafers before use, by heating them for 1 hour at the temperature needed during the pre-deposition (but not lover than 1050 degrees Celsius). During the process a boron phase layer is created on the device wafers. It can be removed in HF if the wafers are oxidised in the A1 Bor Drive-in + Pre-dep furnace after the pre-deposition.

The Boron Drive-in + Pre-dep furnace is the top furnace tube in the A-stack positioned in cleanroom 2. The furnaces in the A-stack are the cleanest of all furnaces in the cleanroom. Please be aware of that all wafers have to be RCA cleaned before they enter the furnace, and check the cross contamination information in LabManager before you use the furnace.

The user manual, quality control instruction and results, technical information and contact information can be found in LabManager:

Boron Drive-in + Pre-dep furnace (A1)

Process knowledge

Boron drive-in: look at the Dope with Boron page
Oxidation: look at the Oxidation page
Annealing: look at the Annealing page
Boron doping: look at the Dope with Boron page.

Quality Control - Parameters and Limits

Quality Controle (QC) for the processes "Wet1050" and "Dry1050"

QC Recipe:	Wet1050	Dry1050
H₂ flow	3 sccm	0 sccm
O₂ flow	2 sccm	5 sccm
Temperature	1050 C	1050 C
Oxidation time	30 min	100 min

QC limits	Thickness	Non-uniformity
Dry1050	108-114 nm	3 %
Wet1050	286-302 nm	5 %

Overview of the performance of the Boron drive-in + Pre-dep furnace and some process related parameters

Purpose	Drive-in of boron Oxidation of silicon Oxidation of boron phase layer Annealing of the oxide	Oxidation: Dry Wet: with torch (H₂+O₂)
Performance	Film thickness	Dry SiO₂: 50 Å to ~2000 Å (takes too long to make it thicker) Wet SiO₂: 50 Å to ~3 µm (takes too long to make it thicker)
Process parameter range	Process Temperature	800-1150 ^oC
	Process pressure	1 atm
	Gasses on the system	O₂, H₂ and N₂
Substrates	Batch size	1-30 4" wafer (or 2" wafers) per run
Substrates	Substrate material allowed	Silicon wafers (new or RCA cleaned wafers) From A2 furnace directly (e.g. incl. Predep HF)

Purpose	Doping of boron
Performance		Look at the process knowlege
Process parameter range	Process Temperature	900-1150 ^oC
	Process pressure	1 atm
	Gasses on the system	Ar, N₂
Substrates	Batch size	1-12 4" wafer (or 2" wafers) per run
Substrates	Substrate material allowed	Silicon wafers (new from the box or RCA cleaned) In doubt: look at the cross contamination chart or send a mail to the Furnace group.