EED NCL

Welcome to the Nanoelectronics Computation Laboratory (NCL) of the Dept of Electrical Engineering. This lab facilitates running TCAD simulations at a transistor level and also simulations related to VLSI on-chip interconnects. TCAD stands for Technology CAD, the technology aspect implying process/material technology. In other words, TCAD tools let you simulate the effects of process and material related parameters (etch rate, material work function, channel doping, physical models (and their controlling parameters) for various physical effects like recombination/generation, band-to-band tunneling, etc), by spatially solving the key partial differencial equations that govern the physics of semiconductor devices and on-chip interconnects. As of Mar 2022, the above machines are physically located in EED's Microwave Lab in C-Block 2nd floor. This is a temporary arrangement, and they will eventually be moved to a dedicated NCL Lab in C-Block 1st floor.

In line with trends at leading institutions, it is intentionally being named as a NCL Lab and not as a TCAD Lab because it is not intended to be limited to TCAD alone, but rather grow in time to develop expertise in development of algorithms/software/numerical-techniques also, all in areas related to semiconductors. These are areas like the development of custom-developed, homegrown simulators for device simulation including but not limited to Monte Carlo simulators, etc as also sundry areas related to EDA algorithms like parameter extraction, circuit simulators, Boolean minimization, synthesis, etc.

The TCAD tools that we have in this lab are Synopsys Sentaurus and Synopsys Raphael. The former is a TCAD tool for semiconductor transistor process and device simulation while the latter is a field-solver intended primarily for on-chip interconnects. Simulations can be either 2D or 3D.

IMPORTANT: Pools of Machines and User Allocation

We presently have two 3D licenses and three 2D licenses for the TCAD tools. It is our understanding that these license limits are enforced at an individual executable level. In other words, running svisual to visualize a 3D structure and running a 3D simulation using sdevice does not count as two 3D licenses being used. Rather, it counts as only one 3D license in use. This is what has been categorically informed to us by our designated support agency Eigen Technologies, this undcerstanding needs to be ascertained.

Due to the limited number of licenses, we have defined 2 pools of machines along with the specified user-machine allocation shown below so as to load-balance the machines appropriately:

1. Pool#1 for 2D simulations:
   1. eleclab-tcad02.snu.in: Bhavith Dulipalla, Kiran G
   2. eleclab-tcad03.snu.in: S. Bhanoday
   3. eleclab-tcad04.snu.in: Dr Amitabh Chatterjee and Dr Venkatnarayan Hariharan
2. Pool#2 for 3D simulations:
   1. eleclab-tcad01.snu.in: Krishna Madhur Akella, Jyothi Pillai, Dr Jitendra Prajapati

Pool#2 obviously comprises beefier machines. Per Synopsys SOLVNET Article# 000033256 dated April 2021, 3D simulations need minimum 128GB RAM, a CPU with 10 or more cores and ample L2 cache, a graphics card with 5GB video memory (VRAM). On the other hand, 2D simulations need only 16-32GB RAM and a graphics card with 2GB VRAM.

Features

• All users have their own individual logins and private work areas, the username is your NetID and your password is your usual email password.
• The file-system is networked and your home directory is /nfsshare/<username>@SNU.IN with a disk quota of 10 GB, it is accessible from any machine. You don’t have to remember this, just typing cd or cd $HOME will take you to your home directory. Despite it being a networked file-system, you must work on your allocated machine only, so as to load-balance the systems appropriately.
• You are advised to be conversant with basic Linux commands, for which you can use:
  • https://www.crio.do/blog/20-basic-linux-commands/
  • https://www.hostinger.in/tutorials/linux-commands
• Additional scratch space on the local disk (ie. local to that machine only) is provided on /home/scratch/<username>. You likely will not need this unless:
  • You need to store files larger than 10 GB, or
  • On the rare occasion that disk i/o under /nfsshare/… is slowing things down too much when reading/writing files

Users Responsibilities

1. You need to inform the TCAD system administrator when you are done with your work in NCL and you no longer need access, so that your account can be deactivated and resources freed up and re-allocated to someone else who needs access.
2. Do not restart/shutdown or install updates even if it appears like its letting you do so.
3. No eating or drinking in the lab
4. No shouting in the lab
5. Keep the lab neat and tidy

Remote Connectivity

For best performance and productivity, one is encouraged to work by being physically present in the lab. But the machines can also be accessed remotely using Windows Remote Desktop Connection software (RDC). The “.snu.in” suffix is not needed when connecting from within the SNU network (hostels, other labs, faculty cabins, etc). If one wishes to connect from outside the SNU campus, then one will need VPN access from SNU IT.

Useful RDC Settings

• To enable ALT-TAB to work as we usually expect: Click RDC → Show Options → Local Resources tab → For "Apply Windows key combinations" select the option "On this computer".
• To copy/paste clipboard contents from Unix to Unix:
  • Using mouse: Select on Unix and then paste by clicking middle-mouse button
  • Using keyboard (KB): Select on Unix and click ctrl-shift-c, and then paste using ctrl-shift-v
• To copy/paste from Unix to Windows:
  • Select on Unix and type ctrl-shift-c
  • Then go to target Windows application and paste as usual in Windows (using mouse/KB/whatever)
• To copy/paste from Windows to Unix:
  • Copy as usual in Windows (using mouse/KB/whatever)
  • On Unix press ctrl-shift-v

Miscellaneous tips/troubleshooting

• Occasionally you may encounter a black/blank screen when you try connecting using RDP client. If this happens, click in the middle of the screen or hit enter a couple of times. It should get resolved. If it doesn’t, close the RDP client session and re-invoke it. This has often been found to fix it.
• From any machine you can go to any other machine by running: ssh <username>@<other machine name>. For example: ssh venkatnarayan.h@elecllab-tcad02
• You can copy files across TCAD machines by running: scp <local file name> <username>@<other machine name>:<path> where can be any path or . indicating your home directory on that machine. For example: scp some_file.txt venkatnarayan.h@elecllab-tcad02:.
• You can copy files across users workareas on the same machine using /tmp as a temporary placeholder (which is local to that machine and can hold very large files, but is not guaranteed to remain for long; gets wiped out upon reboots)