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''By Bjarke Thomas Dalslet @Nanotech.dtu.dk''
''By Bjarke Thomas Dalslet @Nanotech.dtu.dk''


The Lesker CMS 18 sputter system provides thin films of varying surface roughness. This roughness was verified to be dependent on the sputtered material, sputter mode (DC or RF) and the substrate bias strength. Other probable factors include sputter power and pressure. Below is a table for three cases.
The Lesker CMS 18 sputter system provides thin films of varying surface roughness. This roughness was verified to be dependent on the sputtered material, sputter mode (DC or RF) and the substrate bias strength. Other probable factors include sputter power and pressure.  


The "From SiO<math>_2</math> target (RF sputter)" study was done on clean Si substrates. The sputter power was 157W and the pressure 3.5 mTorr using RF sputtering of a SiO<math>_2</math> target. The film thicknesses were around 42 nm.
The surface roughness dependence on a range of sputter parameters can be found in the following pages for:
*[[Specific_Process_Knowledge/Thin_film_deposition/Deposition_of_Silicon_Oxide/Deposition_of_Silicon_Oxide_using_Lesker_sputter_tool|SiO<sub>2</sub>]]


The "From Si target (DC sputter)" study was done on clean Si substrates. The sputter pressure 3 mTorr using DC reactive sputtering of a Si target. Oxygen was added to the argon sputter gas. Above 10% O<math>_2</math> the gun seems to oxidize (at this sputter power). Figure 1 shows the difference in AFM images between no RF bias (wafer 12) and RF bias (Wafer 21).


The "Ta" study was done on clean Si substrates. The sputter pressure was 3 mTorr using DC sputtering of a Ta target. Some O<math>_2</math> was added to wafer 25 and 26 to make Ta<math>_2</math>O<math>_5</math>. In order to get fully oxidized films, up to 30-45% O<math>_2</math> should be added. Consult the thesis of Carsten Christensen for details on Ta<math>_2</math>O<math>_5</math>.
The "Ta" study was done on clean Si substrates. The sputter pressure was 3 mTorr using DC sputtering of a Ta target. Some O<math>_2</math> was added to wafer 25 and 26 to make Ta<math>_2</math>O<math>_5</math>. In order to get fully oxidized films, up to 30-45% O<math>_2</math> should be added. Consult the thesis of Carsten Christensen for details on Ta<math>_2</math>O<math>_5</math>.
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Other studies on metals (NiFe/MnIr)  show only limited effect of the substrate bias on the roughness.
Other studies on metals (NiFe/MnIr)  show only limited effect of the substrate bias on the roughness.


===From Si target (DC sputter)===
{| {{table}} border="1" cellspacing="0" cellpadding="8"
| align="center" style="background:#f0f0f0;"|'''Wafer nr'''
| align="center" style="background:#f0f0f0;"|'''RF bias (W)'''
| align="center" style="background:#f0f0f0;"|'''Reactive O2 (%)'''
| align="center" style="background:#f0f0f0;"|'''Power(W)'''
| align="center" style="background:#f0f0f0;"|'''Rq (RMS) (nm)'''
| align="center" style="background:#f0f0f0;"|'''Thickness'''
|-
| 12||0||5||135||1.44||123 nm (ellipsometry)
|-
| 13||0||9||130||1.32||98 nm (ellipsometry)
|-
| 14||0||13||100||1.37||71.5 nm (ellipsometry)
|-
| 15||10||9||90||0.984||56.25 nm (ellipsometry)
|-
| 21||20||9||90||0.112||
|-
| 22||15||9||90||0.509||
|-
|}




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|-
|-
|}
|}
[[Image:Lesker_roughness_Bjarke.JPG|left|600px|thumb|Figure 1:Left: no RF bias (wafer 12) gives high roughness. Right: RF bias (Wafer 21) gives low roughness]]
<br clear="all" />


==Stress in deposited films==
==Stress in deposited films==
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