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, however the oxidation rate is slow for dry oxide. 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 oxidation is used from 5 nm - 200 nm and can be grown in the furnaces: A1, A2, A3, C1, C3.
• Wet oxidation is used up to 4 µm and can be grown in the furnaces: A1, A3, Nobel.
• Very thick oxide >4 µm can be grown in D1, it is still a wet oxidation.

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

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 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 of 6" wafers. Oxidation of new wafer with out RCA cleaning. Oxidation of wafers from the LPCVD furnaces and PECVD1.	Oxidation of wafers from EVG-NIL, PECVD3 and wafers with aluminum.	Oxidation of very thick oxides, thickness higher than 4 µm.	Oxidation of almost materials on silicon wafer.
Oxidation method	Dry: O2 Wet: Torch	Dry: O2	Dry: O2 Wet: Torch	Dry: O2 Wet: Steamer	Dry: O2 Wet: Bobbler	Dry: O2 Wet: Bubbler	Dry: 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. 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.