Photolithography Overview for MEMS

[@mihirtailor2949]

At 5:29 the figure is wrong for the negative resist. As you said the region exposed to UV become insoluble therefore if that red color is the mask then the final structure will be as same as the positive resist.

[@billpham8261]

i think they fix it

[@the_eminent_Joshua_E_Hrouda]

Ok, so how can we start making these at home now? Already got a setup for making PCBs using the photographic method. How do I put down a layer of silicon dioxide or polysilicon?! How do I make my masks/artwork/reticles?? Already having trouble with sub 8 thou accuracy.

[@cosanostra8341]

Hallo thank you v much for the video!! could you please tell me why could the photoresist have a taper after the ion implantation? does the HMDS prime time have an effect on the taper? when could we have an overcut/undercut profile? thank you!!!!!!!!!

[@isjoker22]

Not sure of their source, but the Si substrate IS breakable. It's kind of neat when they do break, because it's a clean break. If you chip one on an edge it is likely to sever with a known path along a given plane.

[@Sthriven]

At time 1:41, we see that the photosensitive layer is already shaped when placed onto the underlying layer. How are we able to control that shape?? And then at 8:48, we see the mask blocking off certain UV paths onto the part. Is the shape of the layer to be etched determined by the photosensitive layer under a blanket of UV? or does the UV layer control the photosensitive layer, which then controls the etched layer? Thank you

[@Unbrutal_Rawr]

The shape of the photosensitive layer is controlled by subjecting it to photons through a mask, as most of this video explains. The UV layer is the same as the photosensitive layer because UV is light, i.e. photons.

[@melentievr]

3:24 - Hydrophobic usually indicates on low surface energy and low work of adhesion. PDMS is a rare exemption.

[@victor3068]

how are the patterns themselves made so miniscule?

[@БидонКадыкавич-х2ц]

Cool but where are the MEMS

[@sarahsal431]

It was great! You made it clear for me to understand the steps :) Thank you very much

[@AdarshNairaddiedazzler]

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[@AdarshNairaddiedazzler]

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[@AdarshNairaddiedazzler]

I have to do the

[@AdarshNairaddiedazzler]

Tt and I

[@AdarshNairaddiedazzler]

I have to tt the

[@planungplanung7193]

Very very cool videos! A little bit sad, that they are not HD! Anyhow, THANK YOU!

[@ilgapr24]

Excellent!Lucid Explanation

[@AbdulRahman-ju8li]

Thank you, very clear explanation in this video! :)

[@lukehill6272]

Hopefully someone with the expertise and knowledge can help me here I cannot find my answers anywhere... I have been tasked to produce a power point on LED manufacturing and its requirement for vacuum. id be forever grateful for any the answers to any of these questions I've watched endless videos on KZbin. Thanks in advance. The questions are: 1)A wide variety of systems used in LED manufacture require a certain level of vacuum pressure, what is the necessity for vacuum in this environment? 2) what are the various methods of achieving low and high vacuum pressure (pumps) 3) what measurement systems are used to indicate the various ranges (gauges)

[@rudycramer225]

I hope you got through it. I notice no answers here.

[@DoisKoh]

Where's the part about etching!!!?

[@MRGCProductions20996]

after the photolithography, why doesnt the etch, etch the protected silicon oxide (under the undeveloped photoresist) from the side, which is clearly not protected anymore?

[@Unbrutal_Rawr]

A solid silicon oxide layer has no sides, it's a layer covered by the photoresist pattern.

[@MRGCProductions20996]

what i'm trying to say is that (it may be a very thin layer, but its still 3D, just like everything else in this universe) first the whole layer is covered with photo-resist. After the UV light is applied, the affected resist is kind of "rinsed" off (correct me here if i'm wrong). This leaves some portions of the oxide layer unprotected, so when the etch is applied, its corroded (also correct me if i'm wrong). On the minute 1:23 you can see the before and after the etching process. In the second picture, you can see that now, some sides of the oxide layer are exposed.

[@Unbrutal_Rawr]

Yes, you're right there: the sides are now exposed, but the etching has already been done. Some etching processes result in some of the side walls being etched away, others don't. There's no further etching performed on the exposed sides, instead the gaps are filled with whatever they need to be filled with and then the a new oxide layer is applied.

[@MRGCProductions20996]

Oh yes, I must have misunderstood the way the etching process works. Please forgive my stubbornness, but my doubt is about WHILE the etching process is being done. I draw it in paint to explain myself better: imgur.com/a/tYhtQ

[@Unbrutal_Rawr]

Well, again, there are processes that result in both types. The one you have in mind calls for an anisotropic process which can be dry (typically plasma) as well as wet (such as an acid). I only learned about it when writing this reply myself so that's all the detail I know on the matter, but I hope it helps. Thanks for asking by the way, answering your question made me learn something new.

[@pravinvarade3161]

Which material is used as mask with proper justification ?

[@bernestnanga208]

it was an amazing presentation. thank you

[@isjoker22]

It doesn't have to be, it could be made of GaAs as well as several others. Certain atoms are more beneficial in particular situations. But, I believe Silicon is the cheapest to work with and is MUCH more abundant than others. And is thus used more frequently that most others.

[@JoystuckTV]

Hello, great illustration thank you. Got one simple question though. There most definitely some diffraction going after the light has passed the matrix (the perforated plate). Do you use lens system to condense it back to desirable dimensions? If yes, what kinds of them? Thank you!

[@SuperCuriousFox]

This reply is 10 years late, but still: I’d expect that they use the photomask in a mask aligner (or contact aligner) exposure system. These systems align the wafer to the mask and then bring the wafer into contact (or close proximity) for exposure. This minimal distance minimizes the effects of diffraction. The reticle is likely used in a wafer stepper, which often use projection optics to also scale down the features on the reticle when imaged onto the wafer die. Hope that helps, late or not :)

[@thecrazykartbyAJ]

Great video, thank you very much.

[@pravinvarade3161]

Why UV light is used here ? Why not other ? Is it related to resolution ?

[@TanmayvMukim]

X-ray lithography is costly & not easily available, where UV- source as well as UV compatible photo-resists are easily available. (UV-LIGA is cost effective but when the accurate sidewalls in the microstructure are required then we should go with X-ray lithography i.e. LIGA process)

[@maxwelldumont8168]

as the design is on a nano scale, the smaller the wave length, the better. I think

[@TheMyFour]

Great video,thank you. Can you explain what is the pattern?

[@TanmayvMukim]

Its your microstructure, which you want to develop & which is patterned on your mask.

[@joydivisione1420]

How about etching?

[@KevBossche]

in summary: why didn't you use "coat, expose, develop" instead of "coat, develop, expose"!? this is just asking for confusion

[@pradyumnmehra7365]

+Kevin Van den Bossche listen tutorial carefully they did use "coat,expose,develop"

[@pravinvarade3161]

+Pradyumn Mehra In summery it is mentioned as "coat, develop, expose" Why ?

[@toni5ify]

very great clear explanation thanx

[@otimemmanuel953]

Thanks alot. I learnt something

[@keikavoosafghahi5753]

Excellent

[@aaronzvz]

Thanks for the video.

[@bloggervista]

alfrotechmods send me here :P

[@mazenosama8558]

me too :D

[@manubelfort9383]

thanks a lot

[@SnowWhite-gf6vj]

They told me to watch this lol