material request - Stycast W 19 epoxy
jwpchen at stanford.edu
Tue Sep 2 14:40:59 PDT 2008
To answer your questions:
(1) Yes, my silicon wafer will have backside pockets topped by
frontside membranes (metal/dielectric stack). After insertion, the
chips should be flush with or recessed into the wafer backside.
(2) The epoxy need to be measured and mixed. I do not yet know how
critical the mixing ratio is... hopefully I can get by without
precision weighing, and just mix by volume.
(3) Regarding ASML, I will see if I can shuffle steps around, such
that there will be no epoxy going into ASML. (e.g. litho PR for
liftoff before insertion then epoxy)
(4) You have a good point about cured polyimide and I will need to
look at dry etch of polyimide. I do not yet know a good etcher for
Mary Tang wrote:
> Hi Peter --
> So, if I understand correctly, you'd like to glue your chips to a
> silicon wafer with chip pockets and process through litho and lift-off?
> A few questions:
> 1. Mixing and applying your epoxy. These are all liquids, correct? Do
> they require weighing or are they pre-measured? We don't really have
> the appropriate balance inside the cleanroom for this. However, we do
> have accurate balances outside the cleanroom (in the wafersaw/CMP
> room.) Would you be applying the epoxy from a syringe? Since the stuff
> appears to have a long working time, I'd suggest mixing outside the
> cleanroom and bringing the syringe (appropriately labeled and enclosed
> in something like a wafer box) into the cleanroom (through the service
> aisle) and applying it in a solvent bench. You could also mix inside
> the lab in a solvent bench, but I have not yet ordered a replacement
> balance as yet (though you are welcome to nag me about this). If you
> will be curing on a hot plate for several hours, please be careful to
> use foil (and not occupy all the hot plates at once.) The concern is
> that the epoxy will be very difficult to remove if it gets on cassettes,
> bench tops, or hot plates, so precautions should be taken to make sure
> none gets on these. If you want to store the unmixed chemicals in the
> lab, please get the appropriate labels from Mahnaz or me. The chemicals
> should be stored in the personal Flammables area. Any solid waste
> should be bagged and placed in one of the Flammables solid waste
> containers in the Litho area.
> 2. Standard litho flow should be OK for contact alignment. Hopefully,
> your desired resolution isn't better than a couple of microns. If this
> is for ASML, please check first with Mahnaz, Ed, and the ASML engineers.
> 3. PR lift-off in metalica should be OK.
> 4. Polyimide lift-off for standard polyimides is not a process we're
> familiar with. Fully cured polyimide is allowed in the gryphon, but is
> typically then very hard to remove by wet cleans. Polyimide that is not
> fully cured is not allowed in the gryphon because off gassing of
> volatile organics could contaminate the system. Polyimide, if I
> remember correctly, is also not typically allowed on the laurell, but
> only on the headway because it does not dissolve in acetone. If you
> really need polyimide in the gryphon, please provide more details (and
> probably another SpecMat request.)
> Peter Chen wrote:
>> Hi specmat,
>> Here is my request:
>> Material - Stycast W 19 epoxy, Catalyst 11, Catalyst 9, from Emerson
>> and Cuming
>> Where -
>> (1) a litho bench (for the exhaust)
>> (2) standard litho flow (after epoxy cure)
>> (3) PR lift-off in Metallica
>> (4) alternatively, polyimide flow at laurell then lift-off in Gryphon
>> Process -
>> (1) Insertion chiplets into backside of pocketed wafer. Mix, apply,
>> and cure epoxy at a wetbench (for exhaust). Epoxy only used on
>> backside of wafer.
>> (2) Downstream to standard litho equipment for other (non-epoxy) litho
>> steps on frontside
>> (3) PR lift-off process in Metallica
>> (4) polyimide lift-off in Gryphon if that can be approved.
>> Notes -
>> (1) I don't need a litho bench per se, I would just like an approved
>> place that has enough exhaust and 120C hotplate for curing
>> (2) Epoxy will be applied by syringe or pipette to chiplet insertion
>> sites only. Goal is to achieve a reconstituted wafer.
>> (3) Cured epoxy should easily handle 155C.
>> (4) The raw epoxy and catalyst can be stored at room temperature,
>> preferably in lab.
>> (5) After chiplet insertion into wafer backside, my process is to have
>> metal lift-off on frontside to complete the electrical contacts. I
>> need to cover some frontside topography, hence sputtering.
>> I have attached datasheet and MSDS. Please let me know if there are
>> other things I should bring to specmat.
>> -Peter Chen
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