Subject: RAITH Circles parameters for exposure
From: James Conway <jwc@snf.stanford.edu>
Date: Wed, 01 Dec 2004 12:18:40 -0800
Wed, 01 Dec 2004 12:18:40 -0800
Greetings Raith Users:

In my previous post to the group 
<http://snf.stanford.edu/cgi-bin/ezmlm-cgi?2160:mss:1011:200411:ldbnccgiobbbjhgemlhi>

last week I made a mistake in the parameter specifications stated 
regarding the parameters used to write RAITH circles.  I checked with 
RAITH application specialist Joseph Klingfus and reiterated the 
parameters for RAITH circles.  Specifically RAITH circles uses the AREA 
DOSE specification and not the SINGLE PIXEL LINE DOSE.  David Fattal was 
the first to bring this to my attention.

RAITH circles specifically generated using the RAITH editor and not any 
open path element such as single pixel lines:

Area step establishes the interval between the nested rings of RAITH 
circles written as a single pixel line element.
Area dwell time is used from the defaults established in the exposure 
dialog box.
AREA DOSE is used to establish the dose to reach by varying dwell time 
for any Beam Current measured.

More notes specific to the very nice work Ofer Levi is doing on his project:
RE: Circularity of circles written using RAITH circles:
While there is not a system specification for circularity of circles 
written using RAITH circles there are several factors that would greatly 
influence circularity of the exposure result:

   1. Proper Writefield Alignment must be completed or you will
      generated ellipses based on the result of the ZOOM U, V
      parameters.  This is a decided challenge in recent months because
      images drift during image acquisition.
   2. Beams speeds should be minimized and within the optimized
      parameter space, i.e., you must have beam speed below 10 mm/sec
      with an optimal value between 4 and 6 mm/sec for best results.
   3. Sample Surface charging particularly with oxide and nitrides
      underlying the PMMA.  Use a charge compensation coating to reduce
      or eliminate sample charging.
   4. Intra pattern proximity effects could  have a minor effect on
      Photonic crystals circularity , particularly at the defect site
      added to a PC if it is greatly reduces the dimension between
      elements.
   5. Careful and consistent development time and gentle technique must
      be maintained or the CD dimension of the circles will vary greatly
      from sample to sample run.


Hope that this information is useful to everyone.  Anyone care to 
comment on measurements they have made on Photonic Crystals or any RAITH 
circle writes? 

Thank you for your support!

James Conway

David Fattal wrote:

> Hi James,
>  
> I thought only the area dose parameters were used to write the Raith 
> circles. Are you saying the Single Pixel Dose matters as well ? How 
> sure are you about this ?
>  
> David.
>  
>  



Greetings Raith Users:

In my previous post to the group last week I made a mistake in the parameter specifications stated regarding the parameters used to write RAITH circles.  I checked with RAITH application specialist Joseph Klingfus and reiterated the parameters for RAITH circles.  Specifically RAITH circles uses the AREA DOSE specification and not the SINGLE PIXEL LINE DOSE.  David Fattal was the first to bring this to my attention.

RAITH circles specifically generated using the RAITH editor and not any open path element such as single pixel lines:

Area step establishes the interval between the nested rings of RAITH circles written as a single pixel line element.
Area dwell time is used from the defaults established in the exposure dialog box.
AREA DOSE is used to establish the dose to reach by varying dwell time for any Beam Current measured.

More notes specific to the very nice work Ofer Levi is doing on his project:
RE: Circularity of circles written using RAITH circles:
While there is not a system specification for circularity of circles written using RAITH circles there are several factors that would greatly influence circularity of the exposure result:

  1. Proper Writefield Alignment must be completed or you will generated ellipses based on the result of the ZOOM U, V parameters.  This is a decided challenge in recent months because images drift during image acquisition.
  2. Beams speeds should be minimized and within the optimized parameter space, i.e., you must have beam speed below 10 mm/sec with an optimal value between 4 and 6 mm/sec for best results.
  3. Sample Surface charging particularly with oxide and nitrides underlying the PMMA.  Use a charge compensation coating to reduce or eliminate sample charging.
  4. Intra pattern proximity effects could  have a minor effect on Photonic crystals circularity , particularly at the defect site added to a PC if it is greatly reduces the dimension between elements.
  5. Careful and consistent development time and gentle technique must be maintained or the CD dimension of the circles will vary greatly from sample to sample run.

Hope that this information is useful to everyone.  Anyone care to comment on measurements they have made on Photonic Crystals or any RAITH circle writes? 

Thank you for your support!

James Conway

David Fattal wrote:
Hi James,
 
I thought only the area dose parameters were used to write the Raith circles. Are you saying the Single Pixel Dose matters as well ? How sure are you about this ?
 
David.