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Specific Process Knowledge/Thin Film deposition/ALD/TiO2 deposition using ALD: Difference between revisions

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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====


<b>Recipe</b>: TiO2
<b>Recipe</b>: TiO2
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===TiO<sub>2</sub> deposition rates===
====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.   
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.   
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===TiO<sub>2</sub> results===
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.
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.
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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.
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.
 
<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|
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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>
 
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 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 also seen as small white dots in SEM images of the anatase TiO<sub>2</sub> layers above.


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


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Evgeniy Shkondin, DTU Nanolab (former 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.