headers
onny setya | 2 Feb 2009 17:55
Picon
Favicon
Gravatar

hard ashing polymer (if Al deposited): possible isotropic etch by ICP?

--Thank you Jie, but I need undercutting more than 10µm :(

--And thanks again, Ed, I did have an SEM pics of sample no.1, but I could not see clearly whether the polymer
is removed and then the structures got stuck into the substrate, or the polymer is not removed at all.

I will try using NMP and other metal as well for the devices. 
The processes I had are (as u wrote):

1. Spin polymer
2. Deposit SiNx/SiOx
3. Deposit Al
4. Photomask pattern.
5. Etch Al (wet)
6. Etch SiNx/SiOx
7. Strip photoresist (wet first, then plasma) 
8. Oxygen plasma undercut 

About your old-patent, do you mind if I take a look at that´stupid´process? (no idea why u called it like
that though) 

regards, Onny

> From: esebesta <at> tx.rr.com
> To: mems-talk <at> memsnet.org
> Date: Fri, 30 Jan 2009 10:24:20 -0600
> Subject: [mems-talk] hard ashing polymer (if Al deposited): possible	isotropic etch by ICP?
> 
> Dear Onny,
> 
>           The Al is over the SiNx so it can't be leaving a residue on
(Continue reading)

Permalink | Reply | 1 comment |
headers
Edward Sebesta | 2 Feb 2009 20:10
Picon

Re: Double lithography problem with SU1828-TI35ES

For what purpose?

To remove O2, to surface treat for wetability O2. 

Ed 

-----Original Message-----
From: mems-talk-bounces <at> memsnet.org
[mailto:mems-talk-bounces <at> memsnet.org] On Behalf Of basar bolukbas
Sent: Friday, January 30, 2009 2:45 PM
To: mems litho
Subject: Re: [mems-talk] Double lithography problem with SU1828-TI35ES

Hello Edward.

Which kind of plasma treatments are suitable for SU1828? 
Or is it not changeable resist by resist?
I use SU1828 for first lithography and TI35 for second.
I think i will treat SU1828 but i am not sure for the ambient. I can
apply O2 plasma, CHF3, SF6, CCl2 with RIE also.

Which one is suitable do you think?

Thank you for your help.
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

Want to advertise to this community?  See http://www.memsnet.org
(Continue reading)

Permalink | Reply | 0 comments |
headers
Edward Sebesta | 2 Feb 2009 20:53
Picon

hard ashing polymer (if Al deposited): possible isotropic etch by ICP?

http://www.google.com/patents?hl=en&lr=&vid=USPAT4497684&id=TBkyAAAAEBAJ&oi=fnd

The above is the link for the patent. However, I just mention O2 plasma
as a step. It seemed to work easily. I don't remember the details of the
O2 plasma though. 

Ed 

-----Original Message-----
From: mems-talk-bounces <at> memsnet.org
[mailto:mems-talk-bounces <at> memsnet.org] On Behalf Of onny setya
Sent: Monday, February 02, 2009 10:56 AM
To: General MEMS discussion
Subject: hard ashing polymer (if Al deposited): possible isotropic etch by ICP?

--Thank you Jie, but I need undercutting more than 10µm :(

--And thanks again, Ed, I did have an SEM pics of sample no.1, but I
could not see clearly whether the polymer is removed and then the
structures got stuck into the substrate, or the polymer is not removed
at all.

I will try using NMP and other metal as well for the devices. 
The processes I had are (as u wrote):

1. Spin polymer
2. Deposit SiNx/SiOx
3. Deposit Al
4. Photomask pattern.
5. Etch Al (wet)
(Continue reading)

Permalink | Reply | 0 comments |
headers
James Paul Grant | 3 Feb 2009 09:05
Picon
Picon

Deep (~10um) Silicon Dioxide Etching

Hello all,

I'm trying to etch square holes of dimensions ranging from 10um by 10 um 
to 64um by 64um in Silicon dioxide. The problem is I wish to etch 10um 
deep and my photoresist, AZ4562 has a poor selectivity for the various 
fluorine base gases I have tried thus far (CHF4, CHF/O2/Ar, SF6).

I've been doing some reading and metal masks seem to be the solution. 
Has anyone ever done any deep silicon dioxide etching? If so any 
hints/tips/advice would be much appreciated.

Thanks!

--

-- 
Dr. James Paul Grant
Postdoctoral Research Associate
Microsystems Technology Group
76 Oakfield Avenue Room 3
University of Glasgow
Glasgow
Scotland
G12 8LS

Telephone: +44(0)141 330 3374

_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org
(Continue reading)

Permalink | Reply | 10 comments |
headers
Morten Aarøe | 3 Feb 2009 12:04
Picon
Picon

Re: About Silicon On Nothing (SON)

Hi Andrea,

Before trying to make this be sure to spend an hour with a structural 
mechanics simulation to determine how much the structure will bend 
simply due to gravity. I have a very long (2000µm), thin (1µm) 
cantilever, which will drop to the floor below if not hung vertically. 
With a 2000/1 ratio, the drop is on the order a couple of thicknesses. 
Comparing to your numbers it seems you're in the same ballpark. I'm 
guessing you will need support pillars to avoid this.

Of course, in addition to this, it might be very hard indeed to perform 
such a large underetched area using wet etching. Perhaps gas-phase 
etching might be an alternative?

Best of luck
// Morten

Andrea Mazzolari wrote:
> Hi all,
> i need to realize a Silicon On Nothing (SON) structure of lateral size
> about 0.5x0.5mm. Silicon layer should be 20nm, and nothing layer in the
> range 40-60nm.
>
> Some questions:
> 1) which is the best agent to etch SiGe and preserve Si ? (I've found that
> PA:HF:H2O, 1:1:1 where PA=paracetic acid) should have a good selectivity,
> but did not found a numerical estimate.
> 2) is it possible to realize a so large SON structure or the thin silicon
> layer will surely destroy ?
> 3) which will be dislocation density in the thin silicon layer ?
(Continue reading)

Permalink | Reply | 2 comments |
headers
Andrea Mazzolari | 3 Feb 2009 12:38
Picon
Picon
Favicon

Re: About Silicon On Nothing (SON)

Hi Morten,

the structure will stay in vertical position, so i should not have
problems related to gravity.

I think gas-phase etching is a very good possibility. Does someone know
some etchant for SiGe which will preserve the Si layer ?

Thanks,
Andrea

> Hi Andrea,
>
> Before trying to make this be sure to spend an hour with a structural
> mechanics simulation to determine how much the structure will bend
> simply due to gravity. I have a very long (2000µm), thin (1µm)
> cantilever, which will drop to the floor below if not hung vertically.
> With a 2000/1 ratio, the drop is on the order a couple of thicknesses.
> Comparing to your numbers it seems you're in the same ballpark. I'm
> guessing you will need support pillars to avoid this.
>
> Of course, in addition to this, it might be very hard indeed to perform
> such a large underetched area using wet etching. Perhaps gas-phase
> etching might be an alternative?
>
> Best of luck
> // Morten
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
(Continue reading)

Permalink | Reply | 1 comment |
headers
Morten Aarøe | 3 Feb 2009 13:15
Picon
Picon

Re: About Silicon On Nothing (SON)

Hi Andrea,

I have simply used 40% HF in a container and suspended my wafer 
(etch-side down) on top of it. Some references prescribe heating it to 
approx. 40 degrees celsius, but I haven't had any problems with it at 
room temperature. Of course, I was etching SiO2 and not SiGe, so chances 
are that it's not your solution. Since you potentially need 250µm 
underetching with a 20 nm device layer you need to have extreme selectivity.

If you use liquid etchants, I'm afraid that you will have problems with 
capillary forces and/or wetting. The real problem of liquid etchants 
probably is to get it out after etching without bonding your newly 
created Si film to the substrate because of trapped water. This is the 
main reason I went with gas-phase etching. Alternatives include critical 
point drying, but I'm sure people on mems-talk have other ideas.

// Morten

Andrea Mazzolari wrote:
> Hi Morten,
> the structure will stay in vertical position, so i should not have
> problems related to gravity.
>
> I think gas-phase etching is a very good possibility. Does someone know
> some etchant for SiGe which will preserve the Si layer ?
>
> Thanks,
> Andrea
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
(Continue reading)

Permalink | Reply | 0 comments |
headers
Daniel Drysdale | 3 Feb 2009 16:11
Picon
Favicon

Re: Deep (~10um) Silicon Dioxide Etching

Hi James, have you considered HF vapour etching? I know it is pretty useful for SiO2 etching though I am
unsure how your resist will react to the HF vapour. There are a couple of companies that I know of that deal
with this.. One based at Livingston and also within Edinburgh University at their SMC building is
MEMSSTAR who do this kind of work. As I say, I am unsure of the reaction that the vapour would have with the HF
but its a possibility i guess.

Good luck!

Mr Daniel Drysdale
BEng Hons, MSc Eng D 
Research Engineer 
School of Engineering and Physical Sciences
Earl Mountbatten Building 
Room EM 3.32 
Heriot-Watt University Edinburgh, EH14 4AS 
Tel: 0131 451 8316 
Fax: 0131 451 4155 
Email: dd71 <at> hw.ac.uk 
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

Want to advertise to this community?  See http://www.memsnet.org

To unsubscribe:
http://mail.mems-exchange.org/mailman/listinfo/mems-talk
Permalink | Reply | 8 comments |
headers
James Paul Grant | 3 Feb 2009 16:45
Picon
Picon

Re: Deep (~10um) Silicon Dioxide Etching

Thanks Daniel for your thoughts.

Unfortunately I require an anisotropic etch and as i'm sure you know wet 
etching using HF acid or HF vapour is very isotropic. In any case I'd 
have great difficulty attempting to set-up an HF vapour etch set-up in 
our cleanroom at Glasgow. COSHH forms galore!

My main problem is the selectivity of whatever etch I use versus my 
AZ4562 photoresist. At present I can only achieve around 1:1 even for 
low etch rates of ~ 30 nm/min.

I could use a metal mask but here at Glasgow we are not allowed to put 
any substrates with metal on them into the RIE machines.

I've looked into the advanced oxide etch by STS. This looks promising 
for my needs, I just have to convince people here at the university that 
it's worth sending our CMOS chip there to get the 10 um silicon dioxide 
etched!

Cheers

James

Daniel Drysdale wrote:
> Hi James, have you considered HF vapour etching? I know it is pretty useful for SiO2 etching though I am
unsure how your resist will react to the HF vapour. There are a couple of companies that I know of that deal
with this.. One based at Livingston and also within Edinburgh University at their SMC building is
MEMSSTAR who do this kind of work. As I say, I am unsure of the reaction that the vapour would have with the HF
but its a possibility i guess.
(Continue reading)

Permalink | Reply | 4 comments |
headers
Morten Aarøe | 3 Feb 2009 17:10
Picon
Picon

Re: Deep (~10um) Silicon Dioxide Etching

HF vapour etching is isotropic, so etching square 10µm x 10µm holes 10µm 
deep is not possible. What you would get is at best a 20µm circular hole.

I'm currently using this process to release fragile MEMS structures with 
some success. It should be noted, that the only thing you need is a 
container of 40% HF and a way to suspend your wafer above it (etch-side 
down) in a fumehood- I use a PTFE/Teflon cylindrical shell with a 
slightly smaller internal diameter than my wafer, which any workshop can 
make. The etch rate is about 200nm/minute. We use 1.5µm AZ resist, but I 
can't tell you if that's the best solution. It seems OK for 10µm etches 
though.

// Morten

Daniel Drysdale wrote:
> Hi James, have you considered HF vapour etching? I know it is pretty useful for SiO2 etching though I am
unsure how your resist will react to the HF vapour. There are a couple of companies that I know of that deal
with this.. One based at Livingston and also within Edinburgh University at their SMC building is
MEMSSTAR who do this kind of work. As I say, I am unsure of the reaction that the vapour would have with the HF
but its a possibility i guess.
_______________________________________________
Hosted by the MEMS and Nanotechnology Exchange, the country's leading
provider of MEMS and Nanotechnology design and fabrication services.
Visit us at http://www.mems-exchange.org

Want to advertise to this community?  See http://www.memsnet.org

To unsubscribe:
http://mail.mems-exchange.org/mailman/listinfo/mems-talk
(Continue reading)

Permalink | Reply | 2 comments |

Gmane