View source for Specific Process Knowledge/Etch/Etching of Silicon/Si etch using RIE1 or RIE2/Specific Process Knowledge/Etch/Etching of Silicon/Si etch using RIE1 or RIE2/RIE2 Travka results

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=<span style="color:#FF0000"> Both RIE's (RIE1 and RIE2) for silicon based etching has been decommissioned </span> =
* <span style="color:#FF0000"> This information is save because it might be valuable as inspiration for other dry etch systems.
=== RIE2 Travka results - Silicon etch rate and profile as function of etch load===

<b>Purpose</b>

The purpose of the RIE2 Travka experiments is to measure the silicon etch rate and profile as function of the etch load, i.e. of the percentage of the wafer that is etched. 

<b>Experiment</b>

Seven silicon wafers have been etched in RIE2 using the "OH_polyA" recipe. The wafers have been etched in June 2012 by Pernille V. Larsen @nanolab.

All wafers have the same resist pattern ("Travka" masks), but the etch load differs from wafer to wafer. A description of the process flow is show in the table below. For more information about the Travka mask set see [[Specific Process Knowledge/Pattern Design/Travka|Travka masks]].

<b>Measurements </b>

After the etching the wafers have been cleaved, and trenches with different mask widths have been inspected with SEM in order to measure resist etch rate, the Si etch depth, the underetch and the trench width.

==Process flow and parameters==

{| border="2" cellspacing="0" cellpadding="3" 
|-
!style="background:silver; color:black" align="left" rowspan="2"|Photolithography
|style="background:LightGrey; color:black"|Resist thickness
|style="background:WhiteSmoke; color:black"|
*1.5 µm
|-
|style="background:LightGrey; color:black"|Resist masks and etch loads
|style="background:WhiteSmoke; color:black"|
*"Travka5", etch load 5% 
*"Travka10", etch load 10%
*"Travka20", etch load 20%
*"Travka35", etch load 35%
*"Travka50", etch load 50%
*"Travka65", etch load 65%
*"Travka80", etch load 80%
|-
!style="background:silver; color:black" align="left" rowspan="1"|Measure resist thickness 
|style="background:LightGrey; color:black"|Filmtek parameters
|style="background:WhiteSmoke; color:black"|
*Recipe: "RIE_Travka_2points"
*Points: (x,y) = (10,10);(-10,-10)
|-
!style="background:silver; color:black" align="left" rowspan="2"|RIE preconditioning
|style="background:LightGrey; color:black"|Before preconditioning
|style="background:WhiteSmoke; color:black"|
*Check that the "Clean20" recipe has been run
|-
|style="background:LightGrey; color:black"|RIE2 preconditioning parameters
|style="background:WhiteSmoke; color:black"|
*Wafer: dummy wafer
*Recipe: "RIETrav" (same settings as the "OH_polyA" recipe)
*Time: 8 minutes
|-
!style="background:silver; color:black" align="left" rowspan="3"|RIE etching
|style="background:LightGrey; color:black"|Before etching
|style="background:WhiteSmoke; color:black"|
*Remove native oxide in BHF
|-
|style="background:LightGrey; color:black"|RIE2 etching parameters
|style="background:WhiteSmoke; color:black"|
*Recipe: "RIETrav" (same settings as the "OH_polyA" recipe)
*Time: 8 minutes
|-
|style="background:LightGrey; color:black"|Note
|style="background:WhiteSmoke; color:black"|
*Etch all wafers the same day
|-
!style="background:silver; color:black" align="left" rowspan="1"|Measure resist thickness 
|style="background:LightGrey; color:black"|Filmtek parameters
|style="background:WhiteSmoke; color:black"|
*Recipe: "RIE_Travka_2points"
*Points: (x,y) = (10,10);(-10,-10)
|-
!style="background:silver; color:black" align="left" rowspan="3"|SEM characterization
|style="background:LightGrey; color:black"|Note
|style="background:WhiteSmoke; color:black"|
*Cleave wafers at ARDE lines (lower right corner towards the flat)
|-
|style="background:LightGrey; color:black"|Mask trench widths to be measured
|style="background:WhiteSmoke; color:black"|
*2 µm
*4 µm
*10 µm
*50 µm
*200 µm
|-
|style="background:LightGrey; color:black"|Measurements
|style="background:WhiteSmoke; color:black"|
*Trench width
*Si etch depth
*Si etch angle
*Underetch 
|-
|}


==Results==
'''''This work was done by Pernille V. Larsen, DTU Nanolab incl. the images in the PDF document'''''

===SEM images of the etched profiles===
[[Media:RIE2_Travka.pdf|RIE2 Travka result images - click here]]

===Resist etch rate  as a function of mask load===
[[Image:Resist etch rate.jpg]]<br>

===Si etch rate as a function of mask load and line width===
[[Image:Si etch rate2.jpg]]<br>

===Si etch angle as a function of mask load and line width===
[[Image:Si etch angle.jpg]]<br>

===Under etch (under the mask) as a function of mask load and line width===
[[Image:Under etch.jpg]]<br>

===Line width as a function of mask load and line width===
[[Image:line width.jpg]]