Specific Process Knowledge/Thermal Process/Oxidation

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Oxidation

At Danchip we have seven furnaces for oxidation: A1, A2, A3, C1, C3, D1 and nobel. Oxidation can take place either by a dry process or a wet process. The film quality of dry oxide is better than for wet oxide with regards to density and dielectric constant. If the film quality for the wet oxide is acceptable then the thickness and the time it takes to grow the oxide often decides if a dry or wet oxidation is chosen.

• Dry oxide is used from 5 nm - 200 nm. Can be grown in furnaces: A1, A2, A3, C1, C3.
• Wet oxide with O₂ and H₂ can be grown in furnace: A1, A3.
• Wet oxide with H₂O in a bubbler can be grown in furnaces: C1, C3, D1, nobel.

The standard recipes, quality control limits and results for the Boron Drive-in and Phosphorus Drive-in furnaces 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)

Comparison of the six oxidation furnaces

'	A1 Boron drive-in	A3 Phosphorous drive-in	C1 Anneal oxide	A2 Gate oxide	C3 Anneal bond	D1 APOX	Noble
General description	Drive-in of boron deposited in the boron pre-dep furnace(A2) or drive-in of ion implanted boron. Can also be used for dry and wet oxidation.	Drive-in of phosphorous deposited in the phosphorous pre-dep furnace(A2) or drive-in of ion implanted phosphorous. Can also be used for dry and wet oxidation.	Oxidation and annealing of wafers from the B-stack and PECVD1. At the moment also used for general oxidation of 6" wafers.	Oxidation of gate-oxide and other especially clean oxides.	Oxidation and annealing of wafers from NIL.	Oxidation of very thick oxides	Oxidation and annealing for all materials.
Dry oxidation	x	x	x	x(with special permission)	x	.	x (after request)
wet oxidation with torch (H2+O2)	x	x	.	.	.	.	.
Wet oxidation with bubbler (water steam + O2)	.	.	x	.	x	x	x after request
Process temperature [ oC ]	800-1150	800-1150	800-1150	800-1150	800-1150	1075	.
Cleanliness of dry oxide (rated 1-5, 1 is best)	2	2	3	1	4	.	>5
Cleanliness of wet oxide (rated 1-5, 1 is best)	1	1	2	.	4	3	>5
Batch size	max. 30 wafers of 4" or 2"	max. 30 4" wafers or 2" wafers	max. 30 wafers of 6",4" or 2"	max. 30 4" wafers or 2" wafers	max. 30 4" wafers or 2" wafers	max. 200 4"	max. 30 wafers
Which wafers are allowed to enter the furnace:	A1 Boron drive-in	A3 Phosphorous drive-in	C1 Anneal oxide	A2 Gate oxide	C3 Anneal bond	D1 APOX	Noble
RCA clean* Si wafers with no history of Metals on	x	x	x	x (with special permission)	x	.	x
From Predep furnace directly (e.g. incl. Predep HF*)	From A1	From A4	x	.	x	.	x
Wafers directly from PECVD2	.	.	x	.	x	.	x
Wafers directly from NIL bonding	.	.	.	.	x	.	x
All materials must enter the furnace	.	.	.	.	.	.	x

*These wafers must be placed in a "transport box from RCA to furnace" using the RCA carrier when doing RCA or the pre-dep carrier after pre-dep.

	Boron Drive-in	Gate Oxide	Phosphorous Drive-in	Anneal Oxide	Anneal Bond	APOX	furnace
Generel description	Drive-in of boron deposited in the boron pre-dep furnace(A1) or drive-in of ion implanted boron. Can also be used for dry and wet oxidation.	Oxidation of gate-oxide and other especially 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 and annealing of 6" wafers. Oxidation of new wafer with out RCA cleaning. Annealing of wafers from the LPCVD furnaces and PECVD1.	Oxidation and annealing of wafers from EVG-NIL, PECVD3 and wafers with aluminum.	Oxidation of very thick oxides, thickness higher than 4 µm.	Oxidation and annealing of almost materials on silicon wafer.
Oxidation method	Dry: 5 SLM O2 Wet: Torch	Dry: 5 SLM O2	Dry: 5 SLM O2 Wet: Torch	Dry: 5 SLM O2 Wet: Steamer	Dry: 5 SLM O2 Wet: Bobbler	Dry: 5 SLM O2 Wet: Bubbler	Dry: 5 SLM O2 Wet: Bubbler
Annealing gas	N2 Ar	N2	N2	N2	N2	N2	N2 Ar
Process temperatur	900 oC - 1150 oC	900 oC - 1150 oC	900 oC - 1150 oC	700 oC - 1100 oC	900 oC - 1150 oC	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	1-30 50 mm wafers 1-30 100 mm wafers 1-30 150 mm wafers Including one test wafer	Small samples on 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-dep wafer from furnace A1.	All wafers have to be RCA cleaned.	All wafers have to be RCA cleaned. Except for Phosphorous pre-dep wafers from furnace A4.	All processed wafers have to be RCA cleaned. Except for wafers from LPCVD furnace and PECVD1.	All wafers have to be RCA cleaned. Except for wafers from EVG-NIL, PECVD3 and wafer for annealing of aluminum.	Only new wafers	Almost all meterials

Oxidation curves

Generic calculator for wet/dry oxide thickness calculation

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

• Know thickness - want time

• Know time - want thickness

Wet Oxidation on <100>

The curves below are based on measurements in our specific furnaces and give more accurate results.

• 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.