material request - Stycast W 19 epoxy
jwpchen at stanford.edu
Wed Sep 3 23:00:38 PDT 2008
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
(*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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