Chang-Hwan,

As with any process recommendations, remember to perform some test samples
before doing the actual processing on the real samples.  I will attempt to
answer your questions below.  Contact me directly if you have any followup
questions so the forum is not cluttered.

On Tue, 9 Jan 2001, Chang-Hwan Choi wrote:

> I want to deposit Silicon Nitride layer on Si
> substrate which has been already covered with Silicon
> Oxide layer in some part. After that, I will do
> plasma-etching the Nitride in some part for the next
> wet etching step of Si Oxide and Si substrate.

What's the thicknesses of the oxide or nitride layer?

> The equipment for me to use for deposition and etching
> is Plasma Therm PECVD. For etching, I will use
> photoresist as a mask.
>
> For those processes, I have some questions as follows.
>
> 1. Is RCA Cleanning needed before nitride depostion?

Depends on what you have done after the oxide deposition.  If you have
done nothing, it's not necessary.  If you have done lithography or
metallization somewhere, sure, RCA1 (hydrogen peroxide, ammonia hydroxide,
DI) is good.  Keep in mind though that RCA1 may etch some metals.

> 2. Which gases, what temperature(power) and pressure
> are needed for Nitride PECVD? In that condition, what
> is the depostion rate?

Depends on how well quality you want it.  A lot of developed recipes are
propreitary.
For plasmatherm PECVD, there are many generic recipe's, you could probably
contact them for one.

>
> 3. Which thickness of Nitride layer is enough as a
> mask for Si Oxide and Si substrate etching?

Dry etch? If so, will you be needing the Nitride afterward?  CF4/O2
RIE etches both nitride and oxide (and PR too).  YOu want to make sure
your nitride mask is > than oxide thickness.  >> if oxide is thermal
oxide since RIE etches thermal oxide slower.

> 4. Is the potoresist OK as a mask for plasma etching
> of Nitirde?
I don't know if you have access to an RIE.  I hope you're not using the
PECVD to do your etching.
If you use SF6 RIE, PR is a very good mask.  If you use CF4/O2, no.  What
nice about etching nitride on oxide with SF6 is that SF6 stops nicely on
oxide.

> 5. Which gases, what temperature(power) and pressure
> are needed for Nitride Plasma etching? In that
> condition, what is the etching rate?
>
Again, I'd recommend SF6 RIE.  If you have access to it, let me know and I
can give you a general recipe.

> I have referred to many references, but I have no
> experience of Nitride deposition and etching. So, I
> hope to some advices from you all.
>
> Thank you.
>
>
>
> =====
> Chang-Hwan Choi
> Brown University, Box D
> Division of Engineering, 182 Hope Street
> Providence, RI 02912, U.S.A.
>
> Tel: (401)867-6017(H), (401)863-2656(O), Fax: (401)863-9028
> Email: chchoi@rocketmail.com, Chang-Hwan_Choi@Brown.edu
>
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