Hongzhi,

Silver paste or silver epoxy could be the one you are looking for.

Best,

Joseph

----- Original Message -----
From: "Hongzhi CHEN" 
To: 
Sent: Saturday, March 01, 2008 7:33 PM
Subject: [mems-talk] apply bias at the back of silicon substrate


>I have fabricated some devices on the top of the
> silicon dioxide on some heavily doped SiO2/Si wafers.
> And then I want to apply the bias to the heavily doped
> silicon through the backside of substrate, generating
> electric field to change some properties of my devices
> on the top.
>
> I made some PCBs which have big pad on the top. I
> contacted and pressed the back side of the silicon to
> the PCBs. However, it seems the electrical field can
> not be generated in this way, since nothing changed
> after I apply the bias the pads on the PCBs.
>
> I think the contact between the pads and the backside
> of the silicon maybe not good.
>
> Any advice will be appreciated. I heard some people
> put some epoxy at the back of the silicon to make it
> ohmic contact. Does anyone know what kind of epoxy are
> they using? And are there other ways to do it instead
> of using epoxy? Thanks a lot in advanced.
>
> Hongzhi Chen