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Etch rate of Si for different KOH concentrations
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Deposition, Lithography and Etching

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TOPIC: Etch rate of Si for different KOH concentrations

Etch rate of Si for different KOH concentrations 3 years, 9 months ago #47

It is useful to have an idea about the etch rate of (100) silicon in KOH for different concentrations and temperatures whenever you need to do some etching in KOH.

There is a very good book entitled: "Handbook of Microlithography, Micromachining, and Microfabrication, Volume 2: Micromachining and Microfabrication" edited by P. Rai-Choudhury, in which in chapter 2 D.L. Kendall and R.A. Shoultz give an empirical formula for the etch rate of silicon in KOH solutions:

R100=2.6*106*W2.5*exp-(W/300+0.48)/k*(T+273) [μm/hr],

where W is the actual wt% of KOH in water, k is Boltzmann's constant 8.617*10-5 eV/K and T is the temperature in degrees Celcius.

Using this formula one can calculate approximately what will be the etching rate of (100) silicon in KOH. However, the real etch rate may deviate significantly due to many factors.

Below, you will find a graph for the etching rate of silicon (in μm/hr) in KOH for different KOH concentrations and temperatures:

Si_etch_rate_in_KOH_2011-01-10-2.png


If you want to find out more about KOH etching then you can read the following article:
"Overview of KOH etching in microfabrication of MEMS structures".
Last Edit: 3 years, 7 months ago by Administrator.

Re: Etch rate of Si for different KOH concentrations 3 years, 7 months ago #65

Nice. Thanks.
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Re: Etch rate of Si for different KOH concentrations 3 years, 7 months ago #67

What is the etching rate for SiN? What is the minimum thickness for SiN? Thanks.
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Re: Etch rate of Si for different KOH concentrations 3 years, 7 months ago #68

I see. If the Si is 500 um and selectivity is 10000, then we need at least 50 nm SiN.
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Re: Etch rate of Si for different KOH concentrations 3 years, 6 months ago #70

Song,

for high-quality nitride the etch rate in KOH is very low and 50 nm should be sufficient for you. If you want to know more about the etching rates of silicon nitride (and also for some other materials) you can check this topic: memslibrary.com/forum/deposition-lithogr...-processing.html#58.


Song wrote:
I see. If the Si is 500 um and selectivity is 10000, then we need at least 50 nm SiN.
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