Specific Process Knowledge/Thermal Process/Oxidation

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Oxidation

At Danchip we have seven furnaces for oxidation of silicon samples: Boron Drive-in + Pre-dep furnace (A1), Phosphorous Drive-in furnace (A3), Noble furnace, Anneal-oxide furnace (C1), Anneal-Bond furnace (C3), APOX furnace (D1) and Multipurpose Annealing furnace.

Oxidation can take place either by a dry process or a wet process, depending on what furnace that is used for the oxidation. The film quality for a dry oxide is better than the film quality for a wet oxide with regards to density and dielectric constant. However, the oxidation rate is slow for a dry oxide.

• Dry oxidation is used for 5 nm - 200 nm of oxide and can be grown in the furnaces: A1, A2, A3, C1, C3, Multipurpose Annealing
• Wet oxidation is used for up to 4 µm of oxide and can be grown in the furnaces: A1, A3, D1.
• Very thick oxide layers >4 µm can be grown in D1 by a wet oxidation (only performed by Danchip).

The standard recipes, quality control limits and results for the Boron Drive-in + Pre-dep furnace (A1) and the Phosphorus Drive-in furnace (A3) can be found here:

• Standard recipes, QC limits and results for the Boron Drive-in + Predep furnace (A1)
• Standard recipes, QC limits and results for the Phosphorus Drive-in furnace (A3)

The wet oxidation rates for the Anneal-Bond furnace (C1) can be found here:

• Wet oxidation in Anneal-oxide furnace (C1)

Comparison of the seven oxidation furnaces

	Boron Drive-in + Pre-dep (A1)	Gate Oxide (A2)	Phosphorous Drive-in (A3)	Anneal Oxide (C1)	Anneal Bond (C3)	APOX (D1)	Noble furnace
Generel description	Drive-in of boron deposited in the same furnace or drive-in of ion implanted boron. Can also be used for dry and wet oxidation.	Oxidation of gate-oxide and other very clean oxides.	Drive-in of phosphorous deposited in the phosphorous pre-dep furnace (A4) or drive-in of ion implanted phosphorous. Can also be used for dry and wet oxidation.	Oxidation of 4" and 6" wafers. Oxidation of new wafers without RCA cleaning. Oxidation of wafers from the LPCVD furnaces and PECVD2.	Oxidation of wafers from EVG-NIL, PECVD3 and wafers with aluminum.	Oxidation of very thick oxides, thickness higher than 4 µm.	Oxidation of almost all materials on silicon wafers.
Oxidation method	Dry: O2 Wet: Torch	Dry: O2	Dry: O2 Wet: Torch	Dry: O2 Wet: Steamer	Dry: O2 Wet: Bubbler	Dry: O2 Wet: Bubbler	Dry: O2 Wet: Bubbler
Annealing gas	N2 Ar	N2	N2	N2	N2 Ar	N2	N2 Ar
Process temperature	900 oC - 1150 oC	900 oC - 1150 oC	900 oC - 1150 oC	900 oC - 1100 oC	900 oC - 1150 oC 550 oC for aluminium	1075 oC	20 oC - 1000 oC
Substrate and Batch size	1-30 50 mm wafers 1-30 100 mm wafers Including one test wafer	1-30 50 mm wafers 1-30 100 mm wafers Including one test wafer	1-30 50 mm wafers 1-30 100 mm wafers Including one test wafer	Small samples on a carrier wafer, horizontal 1-30 50 mm wafers 1-30 100 mm wafers 1-30 150 mm wafers Including one test wafer	Small samples on a carrier wafer, horizontal 1-30 50 mm wafers 1-30 100 mm wafers Including one test wafer	1-150 100 mm wafers	Small samples on carrier wafer, horizontal 1-25 50 mm wafers 1-25 100 mm wafers, vertical and horizontal
Allowed materials	All wafers have to be RCA cleaned, except for boron pre-doped wafers from the same furnace.	All wafers have to be RCA cleaned.	All wafers have to be RCA cleaned, except for phosphorous pre-doped wafers from furnace A4.	All processed wafers have to be RCA cleaned, except for wafers from LPCVD furnaces and PECVD2.	All wafers have to be RCA cleaned, except for wafers from EVG-NIL, PECVD3 and wafers with aluminum.	Only new wafers	Almost all materials, permission is needed

Oxidation curves

Color chart for oxide/nitride thickness

• View oxide/nitride color vs thickness/angle

Generic calculator for wet/dry oxide thickness calculation

The following links give an approximate oxide time/thickness based on a general formula:

• Know thickness - calculate oxidation time

• Know time - calculate oxide thickness

Deal-Grove parameters

By Kasper Reck-Nielsen February 2015

The following table contains linear and parabolic parameters for use in the Deal-Grove model for thermal oxidation. The parameters are obtained a least squares fit to data available in the furnace logbooks. Information on wafer orientation and doping concentration, which is not available in the logbooks, has not been included in calculating the parameters.

	Anneal Oxide			Anneal Bond			Boron Drive-in			Gate Oxide			Phosphor Drive-in
Recipe	B [µm2/h]	B/A [µm/h]	RMSE [nm]	B [µm2/h]	B/A [µm/h]	RMSE [nm]	B [µm2/h]	B/A [µm/h]	RMSE [nm]	B [µm2/h]	B/A [µm/h]	RMSE [nm]	B [µm2/h]	B/A [µm/h]	RMSE [nm]
DRY900	0.000408	0.107	Too little data	0.0660	0.272	31	0.000390	0.154	Too little data	0.0028	0.079	4 (limited data)	0.0507	0.884	Too little data
DRY1000	-	-	-	-	-	-	0.465	0.838	20	-	-	-	0.641	1.45	41
DRY1050	0.0111	0.526	27	-	-	-	0.0129	0.330	8	0.022	0.505	3 (limited data)	0.0134	0.362	6
DRY1100	0.020	0.930	10	-	-	-	0.0212	0.736	23	-	-	-	0.0313	0.553	14
WET950	-	-	-	-		-	0.0716	1.25	12	-	-	-	0.110	1.17	11
WET1000	0.192	1.54	44	-		-	0.192	1.80	29	-	-	-	0.195	2.49	22
WET1050	0.487	0.965	29	0.477	0.899	Too little data	0.455	1.33	16	-	-	-	0.448	1.73	12
WET1100	0.580	1.43	8	-	-	-	0.519	1.186	3	-	-	-	0.403	9.05	7

Wet Oxidation on <100>

The curves below are based on measurements in our specific furnaces and give more accurate results. We will still recommend to make minimum one test run if the thickness is very important.

• Wet oxidation
• 

  A1 Furnace <100>-Si Wet Oxidation

• 

  A3 Furnace <100>-Si Wet Oxidation

Dry Oxidation on <100> and <111> wafer

• Dry oxidation
• 

  Dry oxide on <100> wafer. The y-axis is in Å and the x-axis is in minutes.

• 

  Dry oxide on <111> wafer. The y-axis is in Å and the x-axis is in minutes.