Specific Process Knowledge/Thin Film deposition/ALD/Al2O3 deposition using ALD

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The ALD window for depostion of Al₂O₃ ranges from 150 ^oC to 350 ^oC. XPS measurements shows that at temperatures below 150 ^oC the Al₂O₃ will be contaminated by unreacted TMA molecules, and at temperatures above 350 ^oC the TMA decomposes.

The deposition rate for Al₂O₃ depends on the temperature, see the graph below.

Al2O3 thickness as function of number of cycles, temperature 150 oC.

In the graphs below the Al₂O₃ thickness as function of number of cycles for deposition temperatures between 150 ^oC and 350 ^oC can be seen. From the equations the number of cycles required for a certain thickess can be calculated. The results have been obtained using the "AL2O3" recipe:

Recipe name: AL2O3

Temperature: 150 ^oC - 350 ^oC

	TMA	H2O
Nitrogen flow	150 sccm	200 sccm
Pulse time	0.1 s	0.1 s
Purge time	3.0 s	4.0 s

• Images of 80 µm thick UV defined SU8 seen from app. 30 degrees imaged with LVD detector
• 
  The LVD detector provides a large field of view and great depth of focus also at low magnification.
• 
  Close-up of the image to the left. The resolution is great.
• 
  Close-up of the image to the left. The resolution is excellent.
• 
  Close-up of the image to the left. The resolution is excellent.
• 
  Close-up of the image to the left. The resolution is excellent.

Al2O3 thickness as function of number of cycles, temperature 150 oC.

Al2O3 thickness as function of number of cycles, temperature 200 oC.

Al2O3 thickness as function of number of cycles, temperature 250 oC.

Al2O3 thickness as function of number of cycles, temperature 300 oC.

Al2O3 thickness as function of number of cycles, temperature 350 oC.

Al2O3 thickness as function of number of cycles, temperature 300 oC.

Evgeniy Shkondin, DTU Danchip, February-March 2014.