[labnetwork] Defects after resist spinning

[Lewis,William]

Typical air bubbles in the resist.  How is being dispensed?

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Bruce Tolleson
Sent: Tuesday, November 2, 2021 4:51 PM
To: Teynor, William A. <wteynor at draper.com>; Lino Eugene <lino.eugene at uwaterloo.ca>; Eva Rose <eva.rose at gno.de>
Cc: labnetwork at mtl.mit.edu
Subject: Re: [labnetwork] Defects after resist spinning

[External Email]
Are you using EBR when coating the wafer?  EBR droplets from a leak could cause this.

Bruce E. Tolleson
Rochester Institute of Technology
82  Lomb Memorial Drive, Bldg 17-2627
Rochester, NY 14623-5604
(585) 478-3836
[http://www.rit.edu/~962www/logos/tiger_walking_rit_color.jpg]

From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Teynor, William A.
Sent: Tuesday, November 2, 2021 12:04 PM
To: Lino Eugene <lino.eugene at uwaterloo.ca<mailto:lino.eugene at uwaterloo.ca>>; Eva Rose <eva.rose at gno.de<mailto:eva.rose at gno.de>>
Cc: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Defects after resist spinning

Hi Eva,

Given the size of the defects and the lack of a comet tail in the resist, it looks like small droplets landed on the photoresist film near the end or after the wafer finished spinning.
The droplets could be from aerosolized photoresist/solvent micro droplets generated during spin coating.
Another possibility would be splashed acetone droplets, from wetting a fabwipe in close proximity.
The defects appears to be surface wrinkling whose pattern is the result of stress minimization in the photoresist skin as the extra solvent dries.


Bill

From: labnetwork <labnetwork-bounces at mtl.mit.edu<mailto:labnetwork-bounces at mtl.mit.edu>> On Behalf Of Lino Eugene
Sent: Saturday, October 23, 2021 9:28 AM
To: Eva Rose <eva.rose at gno.de<mailto:eva.rose at gno.de>>
Cc: labnetwork at mtl.mit.edu<mailto:labnetwork at mtl.mit.edu>
Subject: Re: [labnetwork] Defects after resist spinning

Hi Eva,

It looks like that there is dendritic cristallisation in your defects.

Was the subtrate immersed in RCA 1 or BOE or any solution involving a salt? If so, my first thought is that the substrate was not rinsed properly prior spin coating.

Best,
Lino Eugene

On Oct. 23, 2021 07:46, Aaron Hryciw <ahryciw at ualberta.ca<mailto:ahryciw at ualberta.ca>> wrote:
Hi Eva,

Out of curiosity, did you previously inspect the wafer in an optical microscope using a higher-mag objective than the one used to capture the images?  Given how circular these defects look, and the concentric pattern, my guess is that this is a heating effect, the result of staying too long in one position with a high light intensity.

Cheers,

 – Aaron



Aaron Hryciw, PhD, PEng

Fabrication Group Manager

University of Alberta - nanoFAB

W1-060 ECERF Building

9107 - 116 Street

Edmonton, Alberta

Canada T6G 2V4 Ph: 780-940-7938
www.nanofab.ualberta.ca<https://urldefense.proofpoint.com/v2/url?u=http-3A__www.nanofab.ualberta.ca_&d=DwMGaQ&c=sJ6xIWYx-zLMB3EPkvcnVg&r=KLqajKKMPd-Sg2KTwpmzjQ&m=jwVJmv8P9ZZF0j7YBbBgOUW1x7LmVyAmivwfPESuCWj5_LcuyzEg9fcL9ma8t82H&s=RxEqn39_jig-awmtnAJ-CxE5SajpfiFBiM5ZLiAhukY&e=>


On Fri, Oct 22, 2021 at 5:55 PM Eva Rose <eva.rose at gno.de<mailto:eva.rose at gno.de>> wrote:
Dear all,


did anybody  ever see any defects like this on the resist surface after resist spinning. The diameter varies from about 20um to over 150um.

[cid:17caaeab150a3a20b871]

[cid:17caaeab15074e3f89d2]


Any idea what the reason could be?


Best regards,

Eva
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