I am working on MIM capacitor using gold as my electrode. So, I need to sputter gold as the base electrode and I want to be able to control the thickness as well.
Hello Aaron, I am not sure I understand your question. But if you want to control the thickness of the goad film, there are many way to achieve, you can control the power of the sputter gun, the sputtering pressure, the distance between your gold target and your substrate, or your sputtering time. Different deposition parameter might lead to different of your thin film.
Most thickness monitors do not work in sputter deposition environments. In-order to control the thickness you need to calibrate your system based on time. Unfortunately that is only done by doing several runs of deposition at a certain power, then measuring the thickness of the deposited layer. Many techniques exist to measure deposited layer thickness e.g RBS. You can thus know that at a certain energy how much is deposited per unit time. After that all you will need is a stopwatch to control the thickness.
I would start with some depostion tests by changing parameters like Power,Pressure, and time and try to find the depostion rate first and then continue with it accordingly
Hello Aaron,
As zoung said you can control thickness by changing diffrent parameter and with that you can also use this formula to oobtain the desire thickness.
z/t = M/(rNAe) * S* jp
Where,
M = is molecular weight of the Au,
r= density of the Au,
S= is a sputtering yield
Jp= current density.
By this way you can calculate exact sputtering rate. Once you have exact sputtering rate you can desighn your thickness as you want. I think it is helpull for you.
1. As a first step you have to find the sputtering condition (a combination of DC power, pressure, temperature) that will give you a film of descent uniformity (+/-2-3% on 3-5 points measurements within your substrate). I recommend to base your experiment on the thickness that is reliably measured by the technique you have available;
2. Establish the deposition rate of the process you developed in step #2 by measuring average thickness of the film deposited at different deposition time;
3. Based on the dep rate determined in step#2 Calculate the deposition time necessary to deposit the film of the desired thickness. Create the recipe and run the test run to validate your d.rate/thickness model.
Good luck! Keep in mind: GOLD IS THE EASIEST METAL TO SPUTTER!
Dear Krishnanand Shukla ,
Kindly make your formula clearer by defining what N, A, z, t and e represent. Thank you
NA= Avogadro's Number
z/t is the sputtering rate
e is the charge of electron
Dear Krishnanand Shukla ,
Thank you.
Pls can I get reference to this formula?
yes,
http://iopscience.iop.org/article/10.1143/JJAP.42.5295/pdf
http://www.specs.de/cms/upload/PDFs/IQE11-35/sputter-info.pdf
Yes, Legrand is right. Basically, the sputtering rate also depends on the magnetron property. How much magnetic field is in the center and outer side of the magnetron but you can achieve the similar result in all magnetron by adjusting the position of the substrate holder.
One thing you can do, do profiling of your magnetron and find the magnetic field at the center and find the appropriate current for that particular field. This explanation you can find in any plasma physics book.
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