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The ALD window for titanium dioxide (TiO<sub>2</sub>) ranges from 120 <sup>o</sup>C to 350 <sup>o</sup>C.  
The ALD window for titanium dioxide (TiO<sub>2</sub>) ranges from 120 <sup>o</sup>C to 350 <sup>o</sup>C.  
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For Si wafers, amorphous TiO<sub>2</sub> is best grown on wafers with native oxide, and anatase TiO<sub>2</sub> is best grown on wafers without native oxide (removed using HF).
For Si wafers, amorphous TiO<sub>2</sub> is best grown on wafers with native oxide, and anatase TiO<sub>2</sub> is best grown on wafers without native oxide (removed using HF).


====TiO<sub>2</sub> standard recipe====
====TiO<sub>2</sub> standard recipe====
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!Purge time
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image:ALD_TiO2_grow_rate_350C.jpg| Temperature 350 <sup>o</sup>C.
image:ALD_TiO2_grow_rate_350C.jpg| Temperature 350 <sup>o</sup>C.
</gallery>
</gallery>
Evgeniy Shkondin, DTU Danchip, April-May 2014.


====TiO<sub>2</sub> results====
====TiO<sub>2</sub> results====
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image:TiO2 1000 cycles 300C Si_un.jpg| Temperature 300 <sup>o</sup>C, 1000 cycles.
image:TiO2 1000 cycles 300C Si_un.jpg| Temperature 300 <sup>o</sup>C, 1000 cycles.
image:TiO2 350C 1250 cycles Si_HF_treated.jpg| Temperature 350 <sup>o</sup>C, 1250 cycles, HF treated.
image:TiO2 350C 1250 cycles Si_HF_treated.jpg| Temperature 350 <sup>o</sup>C, 1250 cycles, HF treated.
</gallery>
Below some SEM images of amorphous TiO<sub>2</sub> deposited at 120 <sup>o</sup>C on Si trenches are shown. The width of the trenches is 200 nm, and the depth is 4 µm, i.e. the aspect ratio is 1:20. The number of cycles is 500, and this results in a TiO<sub>2</sub> layer of about 25 nm. From the SEM images it is seen that the TiO<sub>2</sub> layer covers the trenches very well.
<gallery caption="Amorphous titanium dioxide deposited on Si trenches" widths="250px" heights="180px" perrow="3">
image:SEM-TiO2-120C-1.jpg|
image:SEM-TiO2-120C-2.jpg|
image:SEM-TiO2-120C-3.jpg|
</gallery>
Below some SEM images of anatase TiO<sub>2</sub> deposited at 300 <sup>o</sup>C on Si trenches are shown. The width of the trenches is 200 nm, and the depth is 4 µm, i.e. the aspect ratio is 1:20. The number of cycles is 500, and this results in a TiO<sub>2</sub> layer of about 26 nm. From the SEM images it is seen that the TiO<sub>2</sub> layer covers the trenches very well.
<gallery caption="Anastase titanium dioxide deposited on Si trenches" widths="250px" heights="180px" perrow="3">
image:TiO2 trenches-300C-1.jpg|
image:TiO2 trenches-300C-2.jpg|
image:TiO2 trenches-300C-3.jpg|
</gallery>
</gallery>


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[[image:XPS_TiO2.jpg|320x320px|left|thumb|XPS measurements of titanium dioxide.]]
[[image:XPS_TiO2.jpg|320x320px|left|thumb|XPS measurements of titanium dioxide.]]


<br clear="all" />


Evgeniy Shkondin, DTU Danchip, 2014.




====TiO<sub>2</sub> deposition on trenches====


For TiO<sub>2</sub> deposition on trenches more information can be found here:


 
*[[Specific Process Knowledge/Thin Film deposition/ALD/TiO2 deposition using ALD/TiO2 deposition on trenches using ALD|TiO<sub>2</sub> deposition on trenches using ALD]]
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Evgeniy Shkondin, DTU Danchip, 2014.

Latest revision as of 10:27, 19 June 2023

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This page is written by DTU Nanolab internal


The ALD window for titanium dioxide (TiO2) ranges from 120 oC to 350 oC.

A low temperatures between 120 oC and 150 oC an amorphous TiO2 layer is grown in the ALD, and at higher temperatures between 300 oC and 350 oC an anatase TiO2 layer is grown. At temperatures between 150 oC and 300 oC the TiO2 layer will be a mixture of both amorphous and anatase TiO2.

For Si wafers, amorphous TiO2 is best grown on wafers with native oxide, and anatase TiO2 is best grown on wafers without native oxide (removed using HF).


TiO2 standard recipe

Recipe: TiO2

Temperature: 120 oC - 350 oC

TiCl4 H2O
Nitrogen flow 150 sccm 200 sccm
Pulse time 0.1 s 0.1 s
Purge time 4.0 s 5.0 s


TiO2 deposition rates

In the graphs below the TiO2 thickness as function of the 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 to be deposited can be calculated. All results have been obtained for Si wafers with native oxide.

  • Titanium dioxide thickness as function of number of cycles
  • Temperature 150 oC.
    Temperature 150 oC.
  • Temperature 250 oC.
    Temperature 250 oC.
  • Temperature 350 oC.
    Temperature 350 oC.

Evgeniy Shkondin, DTU Danchip, April-May 2014.


TiO2 results

Some some SEM images of TiO2 deposited on a Si surface at different temperatures between 150 oC and 350 oC are shown below. Some of samples have been treated with HF (hydrofluoric acid) to remove the native oxide layer just before the ALD deposition.

  • Titanium dioxide deposited at different temperatures on a Si surface
  • Temperature 150 oC, 1200 cycles, HF treated.
    Temperature 150 oC, 1200 cycles, HF treated.
  • Temperature 150 oC, 1200 cycles.
    Temperature 150 oC, 1200 cycles.
  • Temperature 250 oC, 750 cycles.
    Temperature 250 oC, 750 cycles.
  • Temperature 300 oC, 1000 cycles, HF treated.
    Temperature 300 oC, 1000 cycles, HF treated.
  • Temperature 300 oC, 1000 cycles.
    Temperature 300 oC, 1000 cycles.
  • Temperature 350 oC, 1250 cycles, HF treated.
    Temperature 350 oC, 1250 cycles, HF treated.

XPS measurements of TiO2 deposited at 120 oC and 300 oC are shown below. From the XPS measurements it can be calculated that at temperatures below 120 oC the TiO2 layer will be contaminated with about 1-3 % chlorine molecules from the TiCl4 precursor. This can be also seen as small white dots in the SEM image of the amorphous TiO2 layers above.

XPS measurements of titanium dioxide.


Evgeniy Shkondin, DTU Danchip, 2014.


TiO2 deposition on trenches

For TiO2 deposition on trenches more information can be found here:

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