Specific Process Knowledge/Thermal Process/Dope with Phosphorus

The furnace A4 phosphorus predep(N-predep) can be used to predeposit silicon wafers with phosphor. The silicon wafers are positioned in a quarts boat. Phosphor is predeposited in the silicon wafers.

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Test of Phosphorus Predep furnace

Purpose

To study the coherence between the temperature of the Predep and dive-in for doping with phosphorus in DTU-Danchip Phosphorus Predep furnace (A4).

Experiment setup

There was used 20 boron doped wafers (p-type). There was used four wafer to the five different temperature. There was five dummy wafers on each side of the test wafers. The dummy wafer nearest to the test wafers was changed in between the runes so doping from a dummy wafer was minimized.

Run #	Temperature	Process time with POCl3	Anneal time N2	Wafer #
1	850 oC	15 minutes	20 miuntes	1, 2, 3, 4
2	900 oC	15 minutes	20 miuntes	5, 6, 7, 8
3	950 oC	15 minutes	20 miuntes	9, 10, 11, 12
4	1000 oC	15 minutes	20 miuntes	13, 14, 15, 16
5	1050 oC	15 minutes	20 miuntes	17, 18, 19, 20

After the Predep was two wafer from each run taken out to be further processed. The wafers was 1, 2, 5, 6, 9, 10, 13, 14, 17, 18.

These wafers was dipped in BHF to get the phosphorus glass layer of before the Drive-in process. The Drive-in process was made in Danchip Phosphorus Drive-in furnace (A3). There was a dummy wafer in between the wafers from different temperatures so doping from wafer to wafer was minimized. The Drive-in was done with the process "DRY1050" with is a dry oxidation at 1050 ^oC for 100 minutes and 20 minutes annealing. At the oxdation was the O₂ flow was 5 SLM and N₂ flow for annealing was 3 SLM.