Specific Process Knowledge/Etch/IBE⁄IBSD Ionfab 300/IBE process trends: Difference between revisions
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=Some general process trends= | =Some general process trends= | ||
This page is | This page is gathering some general process trends and good advice for designing IBE recipes. So far these trends have been developed etching Si with resist as masking material and by etching some multilayered films. The work has been done by ''Kristian Hagsted Rasmussen @ nanolab before 2012.'' In the lower section you find optimization tips from Oxford Instruments. | ||
==Etch rate== | ==Etch rate== | ||
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|Beam current * Beam voltage | |Beam current * Beam voltage | ||
|- | |- | ||
|not significantly | |not significantly affected by | ||
|Stage angle | |Stage angle | ||
|- | |- | ||
|not significantly | |not significantly affected by | ||
|Accelerator voltage | |Accelerator voltage | ||
|- | |- | ||
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|Accelerator voltage * Stage angle | |Accelerator voltage * Stage angle | ||
|- | |- | ||
|not significantly | |not significantly affected by | ||
|Beam voltage | |Beam voltage | ||
|- | |- | ||
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==Rotation speed== | ==Rotation speed== | ||
The rotation is activated to get a good uniformity over the wafer. The minimum number of rotations to get a good uniformity is 100 rotations for the whole etch. the maximum rotation speed is | The rotation is activated to get a good uniformity over the wafer. The minimum number of rotations to get a good uniformity is 100 rotations for the whole etch. the maximum rotation speed is 20 rpm. That means that an etch shorter that 5 min cannot obtain a very good uniformity. | ||
{| border="2" cellspacing="2" cellpadding="3" | {| border="2" cellspacing="2" cellpadding="3" | ||
!Etch Length [min] | !Etch Length [min] | ||
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<br clear="all" /> | <br clear="all" /> | ||
=General tips for finding etching parameters (given by Oxford Instruments)= | =General tips for finding etching parameters (given by Oxford Instruments [https://plasma.oxinst.com/products/ion-beam/ionfab], used with permission)= | ||
One thing to remember is that the etch rate varies linearly with beam current while it varies exponentially with beam voltage. | One thing to remember is that the etch rate varies linearly with beam current while it varies exponentially with beam voltage. | ||
*Beam voltage – depends on application, 200-800eV. | *Beam voltage – depends on application, 200-800eV. | ||
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*A guide to optimize etch uniformity is as follows: | *A guide to optimize etch uniformity is as follows: | ||
#Set beam energy —a rough guide is, the higher the energy the rougher the surface as seen on an SEM. | #Set beam energy —a rough guide is, the higher the energy the rougher the surface as seen on an SEM. 500 eV is considered medium energy.<br> | ||
#Then starting with beam current of 300mA increase the value until you reach the value where the PR is getting burnt.<br> | #Then starting with beam current of 300mA increase the value until you reach the value where the PR is getting burnt.<br> | ||
#Adjust beam current to give optimum etch rate without overheating the sample.< | #Adjust beam current to give optimum etch rate without overheating the sample.<br> | ||
#Adjust Accelerator voltage to get uniformity. Note that as this will change beam divergence, the sample temperature will change. | #Adjust Accelerator voltage to get uniformity. Note that as this will change beam divergence, the sample temperature will change. | ||
*Sample temperature is important because:<br> | *Sample temperature is important because:<br> | ||
#Need to keep any resist cool<br> | #Need to keep any resist cool<br> | ||
#Temperature can affect chemical processes | #Temperature can affect chemical processes. | ||