Apr 29

An Interview with Andy Walker

Andy WalkerAndy Walker is Founder and President of Schiltron Corporation, Mountain View, California.

Please tell us a little about Schiltron Corporation?
Schiltron Corporation is a Silicon Valley startup funded to investigate options for 3D Flash.

Wikipedia tells me that a Sheltron or Schiltron is a “compact body of troops forming a battle array, shield wall or phalanx” originating in the Wars of Scottish Independence. Is this the origin of your company name?
Yes indeed. Having grown up and been educated in Scotland, the story of the “schiltron” was embedded in the imagination early on as a crucial military innovation that helped Scotland defend itself against a much more powerful neighbour, namely England. It consisted of tree trunks sharpened at one end to fend off a cavalry charge. Initially defensive as used by William Wallace, it was turned into an attacking formation by Robert the Bruce at the Battle of Bannockburn in 1314. The analogy with the company is that an idea, initially defensive in the form of patents, is turned into an attack that leads to eventual success against much greater powers.

I understand you used to work at Matrix Semiconductor. Can you tell us a little about the company and your role?
I joined Matrix in 2000 to start an effort on 3D multi-programmable non-volatile memory. It was great fun since it combined material science, device physics and product design. I had the good fortune to be able to work with the best in the business. I am proud to say that my team and I were the first to publish on 3D TFT SONOS (at the 2003 VLSI Symposium in Japan). Matrix itself produced a one-time-programmable 3D memory that was quite successful (Johnson et al., IEEE JSSC, Nov. 2003) and absorbed most of the resources with not much left over for my stuff. I left in 2004.

Any idea what has happened to the Matrix team since SanDisk purchased the company?
Many of the key players stayed with the company after acquisition with some rising to the upper echelons of SanDisk. Others left in true Silicon Valley style to join other start-ups.

What gave you the idea of starting Schiltron Corporation?
After Matrix, I started consulting in Silicon Valley in the area of on-chip Electrostatic Discharge protection (my other area of expertise) but always kept up with the literature on thin-film transistor physics and technology and non-volatile memories. My mind kept turning on the problems associated with a contactless string of thin film transistor –based charge trap flash devices, namely disturbs and string current maximization. With a potential solution in mind, I was eager to build the devices to try it out. This needed funding. Therefore, I started Schiltron.

What would you say are some of the unique aspects of Schiltron’s technology?
The Schiltron technology allows the optimization of the charge trap dielectric stack independently of pass disturbs and string current maximization. In other words, it allows the benefits of classic SONOS to be applied in a 3D contactless string of thin film transistors. These include ~ a million program/erase cycles, low voltage program and erase, retention at hot after cycling. And this all with readable worst case string currents even on strings with 64 bits (and probably more). In addition, the elemental cell size per device layer is far smaller than what the vertical channel concepts are capable of.

Any plans or future announcements that you can tell us about?
I can’t say much at the moment but suffice it to say that this year should be interesting.

Where can people find more information about your company and its activities?
The company website (www.schiltron.com) has links to news and white papers. In addition, I’ve written some blog pieces that put things into perspective:
http://bit.ly/1dIrBNO – The recent ReRAM-Forum blog;
http://bit.ly/1m6ef0g – An analysis of Samsung’s V-NAND at the ISSCC;
http://bit.ly/1imVpBb – An analysis of cost of vertical channel 3D NAND in the IEEE;
http://bit.ly/17c1DPw – The first of several blogs on the 3DIncites website on vertical channel 3D NAND.

Thanks Andy! Christie Marrian ReRAM Forum Moderator

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