Hello,

may I have 2 questions?

a) Have you checked the temperature of the wafer? My opinion is that the
resist heating too fast and the results are the colour as you described
and the flakes. If you are using a second wafer to stabilize the
pressure, you need to remove it and use it only at the end of your
process (close to 450 micrometers of etching)
b) Why are you using 3 secs of stabilization of the plasma?
i) your cycling ratio (3s-dep/6s-etch), I have already used (2.5/7.5)
ii) decrease the power of the density 1600-1800 Watts (could be a
significant reason of burning the resist)
iii) change one parameter each time and then combine the parameters i,ii
to take the optiimum results
For example if you try to decrease the Watts and your resist is not
burning then you can change the cycling ratio by adding one sec on the
etching time.

Kind Regrads,
Ioannis

Στις 10/4/2013 10:09 PM, ο/η Orozaliev Ajymurat Nurdinovich έγραψε:
> Hi, thanks for your help.
> It would be great if you could share with that.
>
> I am using 3 step Bosch fast etching.
> 1 cycle:
> 3 sec. dep - 200sscm C4F8-2100 W
> 3 sec. polymer etching - 200sscm SF6 - 1750 W
> 3 sec. isotropic etching- 200sscm SF6 - 2500 W
> 3 sec. plasma stabilization- 200sscm SF6 - 1750 W
>
> After 3 cycles, I can see resist flakes on top of the wafer. and after 5
> cycles I see them all over the place.
>
>
> On Thu, Oct 3, 2013 at 7:08 PM, Ioannis Nikolaou wrote:
>
>> Hello, I think there is a solution for you! I was trying to etch until
>> 450um of Silicon with different photo-resist. My proposal is to change
>> resist like thicker one such as SPR220. I can send you my thesis for
>> further informations, if you need. Can you provide us some informations
>> about the etching recipe?
>> Kind Regards
>> Ioannis
>>
>>
>> 2013/10/3 Orozaliev Ajymurat Nurdinovich 
>>
>>> Hi All,
>>>
>>> I was working on thick AZ9260 resist for using as a mask on DRIE tool.
>>> My target is to etch 450-480 um of Silicon. I have preliminary results
>> for
>>> PR:Si selectivity, which is ~1:25. To etch 450 um of Si, I would need at
>>> least 18 um(but more the better) of AZ9260. With single coating I am
>>> getting maximum of 15 um. But when I do double spinning and expose it,
>> the
>>> resist is turning yellowish-orange. Further, I develope it, but when I
>> put
>>> it inside the DRIE tool, after a few cycles, the resist is forming flakes
>>> and contaminating inside the chamber.
>>>
>>> Here is my recipe:
>>> -2000 rpm - 60 s
>>> -removing edge bead with Acetone, while spinning.
>>> -Soft bake at 110 C for 90 s
>>> -2000 rpm - 60 s
>>> -Soft bake at 110 C for 240 s.
>>>
>>> -Exposure, broadband source,950 mJ/cm2.
>>> -Developer, AZ400:DI 4:1, 3-4 mins.
>>> With this recipe, I am getting ~25 um. but when I put it inside DRIE,the
>>> resist is just peeling of and forming flakes.
>>>
>>> Can you please advise if there is something I am missing?
>>> Also, any recipe would be much appreciated.
>>>
>>> kind regards,
>>> Ajymurat
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> provider of MEMS and Nanotechnology design and fabrication services.
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