cascade possibly not functioning properly

Chien-Yu Chen chienyuc at
Thu Nov 10 20:33:44 PST 2011

Hi Soogine,

I had no problem on Al pads this morning and after your report this issue.  On the same pad each probe pair reaches 100mA compliance in 0.2-0.3V.  So maybe it's the Pt problem like Jason said.


----- Original Message -----
From: "J. Jason Lin" <jasonlin at>
To: "cascade">
Sent: Thursday, November 10, 2011 5:42:45 PM
Subject: Re: cascade possibly not functioning properly

Hi Soogine, 

In case it's relevant, I also had some trouble probing Pt pads in the last few days while probing Al pads was fine. I would get very erratic I-V curves that jumped up and down seemingly randomly and also very low currents. I pressed the probes down a little harder and that seemed to solve the issues. 


On Thu, Nov 10, 2011 at 5:37 PM, Soogine Chong < sgchong at > wrote: 

Hi all, 

I just used cascade and had some issues. It could be a problem with my samples, but, just in case it's not, I thought it'd be helpful to share the issues I've had. 

The parameter analyzer was taking a very long time to measure small current levels, so I rebooted the system. After rebooting, the overall current level dropped significantly, sometimes not showing any signal at all. Also, the currents on the four probes, when all probing on the same Pt pad, didn't always add up to zero. (It looks like the probes on the right side are showing higher current levels than the ones on the left.) 

Possible reasons I can think of: 
-I noticed that the substrate was biased to 3V using the LCR meter by the previous user. Don't know how/why this could be an issue. 
-I was probing on samples that had hardened PR removed with PRX-175. It was the first time I tried this, so it is possible that there was some PR left on the pads. Maybe the tips got coated with PR while probing? 

I would be very interested in finding out how cascade works out for other users after me. Do you see the same issues? 


Soogine Chong 
Stanford University 
PhD candidate in Electrical Engineering 
e-mail: sgchong at 
mobile: +1-650-804-8556 

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