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=<span style="background:#FF2800">THIS PAGE IS UNDER CONSTRUCTION</span>[[image:Under_construction.png|200px]]=
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'''Feedback to this page''': '''[mailto:labadviser@nanolab.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.nanolab.dtu.dk/index.php/Specific_Process_Knowledge/Thin_Film_deposition/ALD/TiO2_deposition_using_ALD click here]'''
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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.


'''Feedback to this page''': '''[mailto:labadviser@danchip.dtu.dk?Subject=Feed%20back%20from%20page%20http://labadviser.danchip.dtu.dk/index.php/Specific_Process_Knowledge/Thin_Film_deposition/ALD/TiO2_deposition_using_ALD click here]'''
A low temperatures between 120 <sup>o</sup>C and 150 <sup>o</sup>C an amorphous TiO<sub>2</sub> layer is grown in the ALD, and at higher temperatures between 300 <sup>o</sup>C and 350 <sup>o</sup>C an anatase TiO<sub>2</sub> layer is grown. At temperatures between 150 <sup>o</sup>C and 300 <sup>o</sup>C the TiO<sub>2</sub> layer will be a mixture of both amorphous and anatase TiO<sub>2</sub>.
 
The ALD window for titanium dioxide (TiO<sub>2</sub>) ranges from 120 <sup>o</sup>C to 350 <sup>o</sup>C.  


A low temperatures between 120 <sup>o</sup>C and 150 <sup>o</sup>C an anatase TiO<sub>2</sub> layer is grown in the ALD, and at higher temperatures between 300 <sup>o</sup>C and 350 <sup>o</sup>C an amorphous TiO<sub>2</sub> layer is grown. At temperatures between 150 <sup>o</sup>C and 300 <sup>o</sup>C the TiO<sub>2</sub> layer will be a mixture of both anatase and amorphous TiO<sub>2</sub>.
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, anatase TiO<sub>2</sub> is best grown on wafers without native oxide (removed using BHF), and amorphous TiO<sub>2</sub> is best grown on wafers with native oxide.


XPS measurements shows that at temperaturs below 120 <sup>o</sup>C the TiO<sub>2</sub> layer will be contaminated with about 1-3 % chlorine molecules from the TiCl<sub>4</sub> precursor. This can be seen as small white dots in SEM images of the anatase TiO<sub>2</sub> layers.


====TiO<sub>2</sub> standard recipe====


<b>Recipe</b>: TiO2
<b>Recipe</b>: TiO2
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In the graphs below the TiO<sub>2</sub> thickness as function of the number of cycles for deposition temperatures between 150 <sup>o</sup>C and 350 <sup>o</sup>C can be seen. From the equations the number of cycles required for a certain thickess can be calculated.


<gallery caption="Titanium dioxide thickness as function of number of cycles" widths="300px" heights="300px" perrow="5">
====TiO<sub>2</sub> deposition rates====
 
In the graphs below the TiO<sub>2</sub> thickness as function of the number of cycles for deposition temperatures between 150 <sup>o</sup>C and 350 <sup>o</sup>C 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. 
 
<gallery caption="Titanium dioxide thickness as function of number of cycles" widths="300px" heights="300px" perrow="3">
image:ALD_TiO2_grow_rate_150C.jpg| Temperature 150 <sup>o</sup>C.
image:ALD_TiO2_grow_rate_150C.jpg| Temperature 150 <sup>o</sup>C.
image:ALD_TiO2_grow_rate_250C.jpg| Temperature 250 <sup>o</sup>C.
image:ALD_TiO2_grow_rate_250C.jpg| Temperature 250 <sup>o</sup>C.
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</gallery>
</gallery>


Some some SEM images of TiO<sub>2</sub> deposited on a silicon surface at different temperatures between 150 <sup>o</sup>C and 120 <sup>o</sup>C are shown below:
Evgeniy Shkondin, DTU Nanolab (former DTU Danchip), April-May 2014.
 
 
====TiO<sub>2</sub> results====
 
Some some SEM images of TiO<sub>2</sub> deposited on a Si surface at different temperatures between 150 <sup>o</sup>C and 350 <sup>o</sup>C are shown below. Some of samples have been treated with HF (hydrofluoric acid) to remove the native oxide layer just before the ALD deposition.


<gallery caption="Titanium dioxide thickness as function of number of cycles" widths="200px" heights="200px" perrow="5">
<gallery caption="Titanium dioxide deposited at different temperatures on a Si surface" widths="250px" heights="180px" perrow="3">
image:TiO2 150C 1200 cycles Si_HF_treated.jpg| Temperature 150 <sup>o</sup>C, 1200 cycles, HF treated.
image:TiO2 150C 1200 cycles Si_HF_treated.jpg| Temperature 150 <sup>o</sup>C, 1200 cycles, HF treated.
image:TiO2 150C 1200 cycles Si_untreated.jpg| Temperature 150 <sup>o</sup>C, 1200 cycles.
image:TiO2 150C 1200 cycles Si_untreated.jpg| Temperature 150 <sup>o</sup>C, 1200 cycles.
image:TiO2 250C 750cycles_Si_untreated.jpg| Temperature 250 <sup>o</sup>C, 750 cycles.
image:TiO2 250C 750cycles_Si_untreated.jpg| Temperature 250 <sup>o</sup>C, 750 cycles.
</gallery>
<gallery caption="" widths="250px" heights="180px" perrow="5">
image:TiO2 1000 cycles 300C Si_HF.jpg| Temperature 300 <sup>o</sup>C, 1000 cycles, HF treated.
image:TiO2 1000 cycles 300C Si_HF.jpg| Temperature 300 <sup>o</sup>C, 1000 cycles, HF treated.
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.
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</gallery>
</gallery>


Below some SEM images of anatase 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.  
XPS measurements of TiO<sub>2</sub> deposited at 120 <sup>o</sup>C and 300 <sup>o</sup>C are shown below. From the XPS measurements it can be calculated that at temperatures below 120 <sup>o</sup>C the TiO<sub>2</sub> layer will be contaminated with about 1-3 % chlorine molecules from the TiCl<sub>4</sub> precursor. This can be also seen as small white dots in the SEM image of the amorphous TiO<sub>2</sub> layers above.
 
[[image:XPS_TiO2.jpg|320x320px|left|thumb|XPS measurements of titanium dioxide.]]
 
<br clear="all" />
 
Evgeniy Shkondin, DTU Nanolab (former DTU Danchip), 2014.


<gallery caption="" widths="250px" heights="250px" perrow="5">
image:SEM-TiO2-120C-1.jpg|
image:SEM-TiO2-120C-2.jpg|
image:SEM-TiO2-120C-3.jpg|
</gallery>


Below some SEM images of amorphous 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.
====TiO<sub>2</sub> deposition on trenches====


<gallery caption="" widths="250px" heights="250px" perrow="5">
For TiO<sub>2</sub> deposition on trenches more information can be found here:
image:TiO2 trenches-300C-1.jpg|
image:TiO2 trenches-300C-2.jpg|
image:TiO2 trenches-300C-3.jpg|
</gallery>


Evgeniy Shkondin, DTU Danchip, 2014.
*[[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]]
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