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 wafer are used for the pre-dep process

The Boron Drive-in + Pre-dep furnace is the top furnace tube in the A-stack positioned in cleanroom 2. 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 yous 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)

The Boron Predep furnace (A2) is used to dope Si wafers with boron to make conductive structures, etch stops layers etc. The doping source is boron nitride wafers (a solid source). The device wafers are placed with the front side towards the source wafers. There are only a few source wafers, i.e. it is not possible to make an entire batch of 25 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 furnace after the pre-deposition.

The Boron Predep furnace is the second top furnace tube in the A-stack positioned in cleanroom 2. The A-stack together with the Gate Oxide furnace (C2) are the cleanest of all furnaces in the clearoom. Please be aware of which substrates are allowed to enter this furnace. Check the Cross contamination chart.

Process knowledge

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

Overview of the performance of the boron drive-in 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)