Specific Process Knowledge/Thermal Process/A1 Bor Drive-in furnace

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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, see http://www.labmanager.danchip.dtu.dk/view_binary.php?fileId=1250 the cross contamination chart].

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 process Wet1050 and Dry1050

The QC procedure for Boron Furnace A1 The newest QC data for wet and dry oxide 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
	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
	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.