material request - Stycast W 19 epoxy
jwpchen at stanford.edu
Thu Sep 11 17:46:50 PDT 2008
I checked with Maurice about gryphon. Due to the wafer handling
arrangement inside, it is best if I use a carrier wafer and kapton
tape. What remains is qualifying the epoxy for vacuum. Is there a
protocol for this approval?
(cc'ed to Ed)
Thanks in advance,
Peter Chen wrote:
> I have indicated the relevant process steps and equipment below:
> (1) start -- semi-clean wafer with frontside membrane and backside
> (2) solvent bench -- insert chiplets and fill gaps with epoxy
> (3) solvent bench -- cure on hotplate, 120 degC
> (4a)headway -- polyimide coat
> (4b)svgcoat -- PR coat, likely SPR220-3 or -7
> (5x)karlsuss/evalign -- expose with lift-off mask
> (5y)asml -- expose with lift-off mask
> (6a)manual develop? -- also cure polyimide
> (6b)svgdev -- develop PR
> (7a)gryphon -- sputter aluminum, no heat
> (7b)metallica -- sputter Al or Au (still need to run tests first)
> (8a) p5000etch + TBD -- dry etch back of Al, then O2 etch polyimide
> (8b) solvent bench -- acetone lift-off of PR
> Note that
> (*a) = draft of polyimide flow
> (*b) = PR flow
> I can try to draw cross-sections for some of the steps if that helps
> Mahnaz Mansourpour wrote:
>> Hello Peter,
>> I need a process flow with indication of equipment use please that
>> would be very helpful to me.
>> 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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