Skip to content. | Skip to navigation

Sections
Personal tools
You are here: Home / Process / Process Modules / Photolithography / Standard Resists at SNF / Shipley 220 Photoresist

Shipley 220 Photoresist

This module covers the procedure for using SPR220-7/3. These two resists are the same formulation at different viscosity. They are used when thicker resists are required, esp for deep Si etching as in the tools stsetch and stsetch2.

SPR220-7 and SPR220-3 PHOTORESIST


WHAT THICK OPTICAL RESISTS ARE AVAILABLE?

Positive Resists:

  • SPR220-7 is used for applications requiring thicker resists, such as Deep RIE etching using one of the STS etchers. (3.5 krpm = 7µm; 1.7 krpm = 10µm; 1krpm =15µm, 2 coats =30µm, 3 coats = 54µm).
  • SPR220-3 is used for shallow etching or when thicker resists are needed.

 

WHEN IS  SPR220-7 USED?

  • When doing deep Si etches in the stsetch or stsetch2 you need to use 7µm without EBR (Edge Bead Removal) of SPR220-7 to prevent etching through the resist and damaging the surface of the wafer. For etches of less than 100um you may choose to use SPR220-3.
  •  For the deep silicon trench etch you need the thick resist, not only as a mask, but also to keep the etch anisotropic (nitride, oxide or metal layers will not give the same etch profile).
  • For DRIE in stsetch, 7µm of SPR220-7 should hold up to about 4 hours of etching (with good wafer cooling). This is sufficient for etching more than 200 µm of silicon. Depending on the size of the holes, it may be adequate for through-wafer etch. Stsetch2, because it is more powerful, will etch both the resist and Si faster.  Please consult recent qualification results found in the stsetch sections.
  • The STS Etcher Etch rate of SPR220-7/3 resist  following 30 minute bake at 90°C in oven, is ~1.5µm/hour (using the holder).

 

WHAT IS THE PROCESS for SPR220-7/3?

  • Use the standard YES oven recipe to singe and prime the samples.
  • If the YES oven is not available, use the singe oven and then  bake/primes station on the svg coater2
    Note: Always keep resist or resist coated wafers under a ventilated exhaust hood. When using the svgcoat, you must keep all plastic panels closed for additional fume protection.
  • Prebake in a 90°C oven or use bake program  of  (100 seconds bake) on SVGCoat.  Then do an additional 100 second bake on a separate hot plate at 115°C. We do have program with 200seconds of bake as well.
  • Postbake for wafers getting stsetch - Oven Bake the wafers for 30 minutes at 110C (or 90°C for ~45 - 60 minutes for etches longer than 2 hours).

 

Aligners for SPR220-7 vs Exposure time:

SVGCOAT setup for 7um of SPR220-7:

prime HMDS  Yes oven

Coat choose the right program on SVGcoat through Program Manager ( many different variation and bake are programmed)

For best results, bake on svgcoat hotplate  for 100 seconds at 90°C . An additional bake of 100 seconds at 115°C will be needed on a separate hot plate . Or you could just  bake at 90°C for 200 seconds on the svgcoat. Your exposure times may vary depending on the thickness of resist.

Note: SPR220-7 Fumes are toxic. Always keep all plastic panels closed on the SVG coater.

 Note, wafers should sit in the Litho  area for minimum of 4 hours before exposure.

Expose Your exposure times may vary depending on the thickness  of the resist, resolution you are trying to resolve and the mask ( transparency masks need much longer exposure).

Develop on svgdev or svgdev2, MF26A,   refer to the chart next to the system,  No postbake is needed. Unless you are doing stsetch.


SVGCOAT setup for 10um of SPR220-7:

prime HMDS   Yes oven

Coat  select 10um programs, spin speed is 1700 rpms). Again we have different variation with different bake time

choose the right program on SVGcoat through Program Manager ( many different variation and bake are programmed)
For best results, bake on svgcoat hotplate  for 100 seconds at 90°C . An additional bake of 100 seconds at 115°C will be needed on a separate hot plate . Or you could just  bake at 90°C for 200 seconds on the svgcoat. Your exposure times may vary depending on the thickness of resist.

 

Note: SPR220-7 Fumes are toxic. Always keep all plastic panels closed on the SVG coater.

Note, wafers should sit in the Litho  area for 24 hours before exposure.

 


Exposure: Your exposure times may vary depending on the thickness  of the resist, resolution you are trying to resolve and the mask ( transparency masks need much longer exposure).

Coat  select 10um programs, spin speed is 1700 rpms). Again we have different variation with different bake time on svgdev or svgdev2, MF26A,  refer to the chart next to the system,  No postbake is needed. 

Unless you are doing stsetch.

 

SVGCOAT setup for15um of SPR220-7:

prime HMDS  yes oven

Talk to staff

Coat  select 15um programs, spin speed is 1000 rpms). Again we could write a recipe according to your need.

Bake on svgcoat hotplate  for 60 seconds at 90°C . An additional bake of 55 minutes in the 90°C oven (wafers need to sit  flat) . Your exposure times may vary depending on the bake you choose.

Note: SPR220-7 Fumes are toxic. Always keep all plastic panels closed on the SVG coater.

It is important to let the wafers sit one or two days  before exposure. Again, talk to staff.

 

Expose  need to run a test wafer as this thickness does not get used as much.

Manual Develop for 5-10 minutes with constant agitation (Stirring unit is available, see SNF staff). No postbake is needed unless you are doing stsetch (see the note for 7µm above).

 

SVGCOAT setup for 45µm of SPR220-7:

prime HMDS yes oven

Coat  (3 coats of 15um with a bake in between and a final bake give 45 µm):

 

After the first and second 15µm layer, bake on svgcoat hotplate program #1 for 60 seconds at 90°C . After the third layer an additional bake of 90 minutes in the 90°C oven (wafers flat) is needed. Your exposure times may vary depending on the bake you choose.

Note: SPR220-7 Fumes are toxic. Always keep all plastic panels closed on the SVG coater.

It is important to let the wafers sit two  days before exposure.

 

Expose need to run a test wafer as this thickness does not get used as much.

Manual Develop  start with 10 minutes and go from there, (stirrer is available - see SNF staff). No postbake is needed unless you are doing stsetch. See note for 7µm above.

 

Document Actions