Lecture 22 (CHE 323) Sputtering, part 1

[@Shumayal]

12:21 From where do we inject the electron into the system? The free electrons that collide with the argon gas in the first place come from where? From the target? EDIT: Ok I just saw your answer about RF stripping the electron from Argon. I am curious how this RF removes the valence electron.

[@brucema5659]

From the cathode behind the target.

[@Nekoflame]

Whoa. Intense voice drop at 1:18

[@ChrisMack]

PDF copies of all the slides in this course are available at: www.lithoguru.com/scientist/CHE323/course.html

[@mohamedashrafmousa3054]

the target should be on the cathode , should not it ? @04:50

[@drted]

At 12:50, I think you mean to say the electron moves in a helix, not a spiral. :)

[@rajathprabhu1021]

If the Pressure is too high, it will cause many collisions resulting in a lower mean free path. Isnt lower mean free path good?

[@Svx_6]

Thank you proffesor for sharing this amazing explain.

[@GhulamNabiDar]

Precisely a very good coverage to sputtering technique..

[@ravimathur5247]

increasing Pressure --> low mean free path --> more collision --->material arrive at wafer from all angles--> good coverage. What is the problem with increasing pressure because of which we are using magnetron sputtering?

[@jedihakan]

As far as I know it is bad because we also want electrons to gain enough energy between collisions. So pressure must not be too low or too high.

[@brucema5659]

High-pressure sputtering produces a lot of problems too. You can produce high-stress films as a start. The film density will be lower. And if you are trying to fill small size vias and contacts, the bottom coverage will be poor.

[@nasrinkazem9620]

Thanks Prof. Mack for very helpful lectures. One question: while Ar cations accelerate towards Cathode, do electrons accelerate towards the wafer (anode)? How do we control the electrons motion to avoid hitting the wafer since I imagine it would severely damage the wafer, right?

[@ChrisMack]

The chamber walls generally serve as a ground for the electrons.

[@analuciamarzocca3748]

Hello! I have an existential question: the machines to make gold sputtering in samples that are going to be observed in the SEM also do the evaporation of carbon that serves to make replicas to observe in the TEM, why do not use the evaporation of carbon for samples of SEM?

[@ChrisMack]

In a SEM, the purpose of the coating is to provide a conductive path for electrons to prevent charging. Thus, the use of a metal.

[@analuciamarzocca3748]

@@ChrisMack i know that, but in my laboratory with use evaporation of carbon only for replicas TEM and gold for samples SEM, can we use evaporation carbon for SEM samples??

[@hanyuanzhang2352]

Can anyone explain why DC power is more fit for metal deposition while RF power is for dielectric?

[@brucema5659]

Argon ions built up at the target surface will have a +ve electric field and will repel additional argon ions to hit the target material.

[@Sebastian-on4fq]

if i want a thin aluminium layer, how the atoms get stick to the wafer ?

[@punksnotdead4766]

they land and they stick there 😂

[@AngadSinghKushwaha9452288059]

Very interesting

[@Jarrod_C]

Ok but when the argon ionizes it will be positively charged and also affected by the magnetic field and spiral itself. How does that affect things?

[@ChrisMack]

It will cause more collisions and more ionization.

[@akammerz]

Can anyone explain how this creates a uniform film on the target?

[@punksnotdead4766]

The film won’t be totally uniform. Plenty papers out there that model film thickness uniformity in terms of target to wafer distance, chuck rotation speed, Ar flow rate, target material wear, plume shape etc. You can also use a sputter mask to improve the uniformity

[@عبداللهالأمين-د8ث]

very intersting