Specific Process Knowledge/Thermal Process/C4 Aluminium Anneal furnace: Difference between revisions

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Aluminium Anneal furnace (C4)

The Aluminium Anneal or Al-Anneal furnace (C4) is a Tempress horizontal furnace for annealing and oxidation of different samples.

The samples can for instance be silicon and quartz wafers or small samples with aluminium or ALD deposited Al₂O₃ and TiO₂. Other materials might be allowed in the furnace, but this requires a permision from the Thin Film group. Also please check the cross contamination information in LabManager, before you use the furnace.

The furnace is the lowest of the C-stack furnaces positioned in cleanroom B-1. .

The user manual, technical information and contact information can be found in LabManager:

Aluminium Anneal furnace (C4)

Process knowledge

Annealing: Look at the Annealing page
Oxidation: Look at the Oxidation page

Overview of the performance of the Aluminium Anneal furnace and some process related parameters

Purpose		Annealing in N₂ Dry oxidation with O₂
Process parameter range	Process Temperature	Normally 350-500 ^oC for wafers and samples with aluminium Up to 1150 ^oC for wafers and samples with other materials
	Process pressure	1 atm (no vacuum)
	Gas flows	N₂ (nitrogen): 0-10 SLM O₂ (oxygen): 0-10 SLM
Substrates	Batch size	1-30 4" wafers (or 2" wafers) 1 6" wafer (2 6" wafers with less good uniformity) - Requires training Small samples placed on a 6" dummy wafer - Requires traning
Substrates	Substrate materials allowed	Silicon and quartz samples with SiO₂ and Si₃N₄ Aluminium. Wafers are allowed to enter the furnace after aluminium lift-off or aluminium etch and resist strip in acetone Al₂O₃ and TiO₂ deposited by ALD Other materials might be allowed, but it requires a permission from the Thin Film group

Oxidation uniformity for 6" wafers

In November 2023 an oxygen (O₂) mass flow controller was connected to the furnace, so that it became possible to oxidize different wafers and samples in the furnace.

The C4 furnace is made for processing of 4" wafers placed vertically in a quartz boat. However, it is possible to process 6" wafers (or small samples placed on a 6" wafer), if they are placed horizontally on the boat.

Normally only one 6" wafer is being processed, because the temperature flat zone, i.e. the area inside the furnace where the temperature is uniform, is only a little longer than one quartz boat. But because there are two quartz boats available for the furnace, it has also been tried to place a 6" wafer on each boat and oxidize them at the same time as explained here.

Sample loading:

One 6" wafer was placed on each of the two quartz boats. The wafer flats were pointing towards each other, and the boats were centered above the arrow on the cantilever. The loading procedure is explained in the user manual for the furnace, but users should not do this without training, as the wafers might collide with the furnace tube, when the door closes (the tube diameter is 160 mm, and the wafer diameter is 150 mm). In order improve the temperature uniformity over the two 6" wafers, two 4" dummy wafers were placed in the end of each boat.

The 6" wafer closest to the furnace door/cleanroom is numbered "w1", and the wafer closest to the furnace/service room is numbered "w2". See the image below.

Process parameters:

For the oxidation, the following process parameters were used:

Recipe: "DRY1050"
Oxidation temperature: 1050 ^oC
Oxidation time: 1 h 40 min

Results:

After the oxidation, the thickness of the oxide layer grown on the 6" wafers was measured in five points on each wafer using the Ellipsometer VASE.

The measurement results are shown below.

Pernille Voss Larsen, DTU Nanolab, November 2023

@@ Line 1: / Line 1: @@
-==C4 Furnace Aluminium Anneal==
+'''Feedback to this page''': '''[mailto:thinfilm@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Thermal_Process/C4_Aluminium_Anneal_furnace click here]'''
-[[Image:image.JPG|thumb|300x300px|C2 Furnace Anneal Oxide: positioned in cleanroom 2]]
-C2 Furnace Anneal Oxide is a Tempress horizontal furnace for oxidation and annealing of silicon wafers.
+''This page is written by DTU Nanolab  internal''
+[[Category: Equipment |Thermal C4]]
+[[Category: Thermal process|C4]]
+[[Category: Furnaces|C4]]
-This furnace is the second furnace tube in the furnace C-stack positioned in cleanroom 2. The furnaces are the cleanest process chambers in the cleanroom. In this furnace it is allowed to enter wafers that comes directly from PECVD1 (assuming they were very clean when entering PECVD1). Check the cross contamination chart. If you are in doubt, please ask one from the furnace team.
+==Aluminium Anneal furnace (C4)==
+[[Image:C4helstak.jpg |thumb|300x300px|Aluminium Anneal furnace (C4). Positioned in cleanroom B-1. /Photo: DTU Nanolab internal]]
+The Aluminium Anneal or Al-Anneal furnace (C4) is a Tempress horizontal furnace for annealing and oxidation of different samples.
+The samples can for instance be silicon and quartz wafers or small samples with aluminium or ALD deposited Al<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub>. Other materials might be allowed in the furnace, but this requires a permision from the Thin Film group. Also please check the cross contamination information in LabManager, before you use the furnace.
+The furnace is the lowest of the C-stack furnaces positioned in cleanroom B-1. .
+'''The user manual, technical information and contact information can be found in LabManager:'''
+'''[http://www.labmanager.danchip.dtu.dk/function.php?module=Machine&view=view&mach=90 Aluminium Anneal furnace (C4)]'''
 ==Process knowledge==
-*Oxidation: look at the [[Specific Process Knowledge/Thermal Process/Oxidation|Oxidation]] page
+*Annealing: Look at the [[Specific Process Knowledge/Thermal Process/Annealing|Annealing]] page
-*Annealing: look at the [[Specific Process Knowledge/Thermal Process/Annealing|Annealing]] page
+*Oxidation: Look at the [[Specific Process Knowledge/Thermal Process/Oxidation|Oxidation]] page
-<br clear="all" />
-==A rough overview of the performance of Anneal Oxide furnace and some process related parameters==
+==Overview of the performance of the Aluminium Anneal furnace and some process related parameters==
-{| border="2" cellspacing="0" cellpadding="10"
+{| border="2" cellspacing="0" cellpadding="2"
 |-
-!style="background:silver; color:black;" align="left"|Purpose
+!style="background:silver; color:black;" align="center"|Purpose
-|style="background:LightGrey; color:black"|Oxidation and annealing ||style="background:WhiteSmoke; color:black"|Oxidation:
+|style="background:LightGrey; color:black"|
-*Dry
-*Wet: with bubbler (water steam + N<math>_2</math>)
+|style="background:WhiteSmoke; color:black"|
-|-
+*Annealing in N<sub>2</sub>
-!style="background:silver; color:black" align="left"|Performance
+*Dry oxidation with O<sub>2</sub>
-|style="background:LightGrey; color:black"|Film thickness||style="background:WhiteSmoke; color:black"|
-*Dry SiO<sub>2</sub>: 10Å  to ~2000Å (takes too long to make it thicker)
-*Wet SiO<sub>2</sub>: 10Å to ~5µm ((takes too long to make it thicker)
 |-
-!style="background:silver; color:black" align="left"|Process parameter range
+!style="background:silver; color:black" align="center" valign="center" rowspan="3"|Process parameter range
 |style="background:LightGrey; color:black"|Process Temperature
 |style="background:WhiteSmoke; color:black"|
-*800-1150 <sup>o</sup>C
+*Normally 350-500 <sup>o</sup>C for wafers and samples with aluminium
+*Up to 1150 <sup>o</sup>C for wafers and samples with other materials
 |-
-|style="background:silver; color:black"|.||style="background:LightGrey; color:black"|Process pressure
+|style="background:LightGrey; color:black"|Process pressure
 |style="background:WhiteSmoke; color:black"|
-*1 atm
+*1 atm (no vacuum)
 |-
-|style="background:silver; color:black"|.||style="background:LightGrey; color:black"|Gas flows
+|style="background:LightGrey; color:black"|Gas flows
 |style="background:WhiteSmoke; color:black"|
-*N<math>_2</math>:? sccm
+*N<sub>2</sub> (nitrogen): 0-10 SLM
+*O<sub>2</sub> (oxygen): 0-10 SLM
 |-
-!style="background:silver; color:black" align="left"|Substrates
+!style="background:silver; color:black" align="center" valign="center" rowspan="2"|Substrates
 |style="background:LightGrey; color:black"|Batch size
 |style="background:WhiteSmoke; color:black"|
-*1-30 4" wafer (or 2" wafers) per run
+*1-30 4" wafers (or 2" wafers)
+*1 6" wafer (2 6" wafers with less good uniformity) - Requires training
+*Small samples placed on a 6" dummy wafer - Requires traning
 |-
-|style="background:silver; color:black"|.|| style="background:LightGrey; color:black"|Substrate material allowed
+| style="background:LightGrey; color:black"|Substrate materials allowed
 |style="background:WhiteSmoke; color:black"|
-*Silicon wafers (new from the box or RCA cleaned)
+*Silicon and quartz samples with
-**with layers of silicon oxide or silicon (oxy)nitride (RCA cleaned)
+**SiO<sub>2</sub> and Si<sub>3</sub>N<sub>4</sub>
-*Quartz wafers (RCA cleaned)
+**Aluminium. Wafers are allowed to enter the furnace after aluminium lift-off or aluminium etch and resist strip in acetone
-*From PECVD1 directly (assuming they fulfilled the above before entering the PECVD1)
+**Al<sub>2</sub>O<sub>3</sub> and TiO<sub>2</sub> deposited by ALD
-|-
+*Other materials might be allowed, but it requires a permission from the Thin Film group
+|-
 |}
+==Oxidation uniformity for 6" wafers==
+In November 2023 an oxygen (O<sub>2</sub>) mass flow controller was connected to the furnace, so that it became possible to oxidize different wafers and samples in the furnace.
+The C4 furnace is made for processing of 4" wafers placed vertically in a quartz boat. However, it is possible to process 6" wafers (or small samples placed on a 6" wafer), if they are placed horizontally on the boat.
+Normally only one 6" wafer is being processed, because the temperature flat zone, i.e. the area inside the furnace where the temperature is uniform, is only a little longer than one quartz boat. But because there are two quartz boats available for the furnace, it has also been tried to place a 6" wafer on each boat and oxidize them at the same time as explained here.
+<b>Sample loading:</b>
+One 6" wafer was placed on each of the two quartz boats. The wafer flats were pointing towards each other, and the boats were centered above the arrow on the cantilever. The loading procedure is explained in the user manual for the furnace, but users should not do this without training, as the wafers might collide with the furnace tube, when the door closes (the tube diameter is 160 mm, and the wafer diameter is 150 mm). In order improve the temperature uniformity over the two 6" wafers, two 4" dummy wafers were placed in the end of each boat.
+The 6" wafer closest to the furnace door/cleanroom is numbered "w1", and the wafer closest to the furnace/service room is numbered "w2". See the image below.
+<b>Process parameters:</b>
+For the oxidation, the following process parameters were used:
+* Recipe: "DRY1050"
+* Oxidation temperature: 1050 <sup>o</sup>C
+* Oxidation time: 1 h 40 min
+<b>Results:</b>
+After the oxidation, the thickness of the oxide layer grown on the 6" wafers was measured in five points on each wafer using the Ellipsometer VASE.
+The measurement results are shown below.
+<i>Pernille Voss Larsen, DTU Nanolab, November 2023</i>
+[[image:Oxidation test 1.jpg|600x600px|left|thumb|Two 6" wafers loaded in the C4 furnace. Two 4" dummy wafers are placed in the end of each boat.]]
+[[image:Oxidation test 2.jpg |700x700px|left|thumb|Oxide thickness measured on the two 6" wafers]]