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Sunday, August 30, 2020

#444 One more time on questionable predictions


This is going back to the post of July 7, 2014 entitled “Predictions, predictions” in which I expressed my disdain with regard to misleading, misinforming, technically frivolous predictions regarding semiconductor engineering often meant to attract attention to a specific self-serving cause.


Not much has changed since then. The problem is of course not with technically sound, well founded in industrial/business reality, and overall, very needed forecasting. The problem is with predictions which can be found in some broadly disseminated semi-technical publications which are meant to grab our attention.  For instance, statement about “chemical computers replacing in about ten years traditional silicon microprocessors-based computers”, or about graphene replacing in the near future silicon in all electronic device applications. And how many times over the years we read about “insurmountable physical barriers”, “red-brick walls”, “limits of technology”, and “ends of the road” among others?


So, what’s the conclusion? Just don’t take for granted everything that you read about the future of semiconductor electronics and photonics and use common sense to see through the often grossly misleading proclamations.


Posted by Jerzy Ruzyllo at 09:26 PM | Semiconductors | Link

Sunday, August 16, 2020

#443 Thirty years ago: August 1990


Not surprisingly, six out of eight papers published in August 1990 issue of IEEE Electron Device Letters were devoted to research on innovative transistors solutions. Whether SOI MESFET, heterostructure FET, high performance BJT, or GaAS FETs, the urge to develop innovative transistor technologies able to meet anticipated future challenges was evident.


At the process side, as some papers published in the August ’90 issue of the Journal of the Electrochemical Society indicate, low-temperature, or rather low-thermal budget processing continued to be of interest. Also, papers devoted to plasma etching, including remote µwave plasma which was a technique attracting significant attention at that time, and RIE were noticed.


Posted by Jerzy Ruzyllo at 11:26 AM | Semiconductors | Link

Sunday, August 9, 2020

#422 Equivalent Gate Length (EGL)

Scaling of the gate length of the MOSFETs comprising advanced logic ICs was for the last fifty years a main tool used to improve transistor’s performance in terms of speed of operation, on/off ratio, circuit density and others. Obviously, shortening of the gate length cannot continue indefinitely and at certain point needed improvements in transistors’ performance will have to accomplished employing other “tools”.


In the blog #379 posted in December 2017, I proposed a concept of the Equivalent Gate Length (EGL) meant to establish connection between gate scaling as a way to improve transistor performance, and alternative solutions involving modifications of transistor architecture and/or material choices potentially resulting in the comparable to gate scaling performance improvements, but implemented without reducing gate length.


Recently announced by Intel expected 20% improvement in transistor performance accomplished by re-engineering of the FinFET while maintaining the gate length at 10 nm is an example of the latter.


I wonder how much the gate length would have to be reduced to accomplish the same 20% improvement in transistor performance. In other words, what would be EGL in the case of the proposed innovative 10 nm “SuperFin” transistor architecture? 7 nm, which would mean full-node improvement, or may be 8 nm? It would be interesting to know this number to better understand the extent of this improvement.

Posted by Jerzy Ruzyllo at 10:40 AM | Semiconductors | Link

Sunday, July 26, 2020

#441 Thirty years ago: July 1990

As indicated in my previous “Thirty years ago” pieces, papers published in 1990 demonstrate “awakening” of semiconductor research community to the fact that the continuation of transistor scaling, basically undisturbed until then, is bound to face challenges moving well below 0.25 µm technology which was more or less a standard at that time.


Various papers in IEEE’s Transactions on Electron Devices and Electron Device Letters point to the anticipated problems with transistor’s drive current in the scaled down devices. The terms “hot-carrier degradation” or “DIBL” (drain-induced barrier lowering) were ubiquitous in the device-related research papers thirty years ago.


In terms of the mainstream silicon manufacturing technology lowering of the temperature of some notoriously high temperature processes was of interest. As an example, paper in the July ’90 issue of the Journal of the Electrochemical Society reported on the successfully implemented epitaxial growth of high-quality silicon at 850oC. Also, wet cleaning of deep trenches was getting attention because of growing at that time need to improve trench isolation technology.

Posted by Jerzy Ruzyllo at 11:20 AM | Semiconductors | Link

Sunday, July 19, 2020

#440 Silicon vs silicone

As a semiconductor purist, I can’t help, but take note of  all too often encountered misuses of semiconductor related terms (see for instance entry #435). As an example, a quote from the piece I recently came across on-line: “…. the plastic mask is secured to your face with a silicon pad…”


I won’t get to into explaining the difference between “silicon” and “silicone”, because it is so obvious. I am just protesting against frivolous misuse of the name of my favorite semiconductor.  Little “e” makes a big difference...

Posted by Jerzy Ruzyllo at 11:17 AM | Semiconductors | Link

Sunday, July 12, 2020

#439 Surface aging

Surfaces of semiconductor wafers during handling, storage, shipping, etc., are unavoidably exposed to moisture, oxygen, and volatile organic compounds present in the surrounding ambient air regardless of whether it is an ultra-clean clean-room, plastic shipping container, or storage box.


The process of adsorption on the wafer surface of the air-born species listed above gradually changes chemical composition of such surface and accounts for what’s known as surface” aging”. As a result, in the matter of days regardless of whether initially hydrophobic or hydrophilic, surface is losing its original wetting characteristics reflecting changes in the surface energy. At its early stage the process of surface “aging” can be reversed by means of the discussed in the previous blog lamp cleaning. If allowed to continue for the longer period of time (e.g. prolonged storage of wafers between processes), only conventional wet cleaning is able to return the surface to its original condition.

Posted by Jerzy Ruzyllo at 05:13 PM | Semiconductors | Link

Sunday, June 28, 2020

#438 Lamp cleaning

Earlier blog #428 was concerned with UV (185 nm and 254 nm) cleaning used in semiconductor processing for the purpose of organic contaminants removal from the processed surfaces. As we all know now, UV light (especially far-UVC, 222 nm) is used for disinfection which basically comes down to the annihilation of organic “contaminants” (if the use of the term “contaminants” in reference to viruses and bacteria is appropriate).


The problem with UV is that it needs to be used (wavelengths selection) very carefully because either through ozone generation or direct exposure it can be very harmful to us.  On the other hand, oxygen plasma, which is even more effective than UV in organic contaminants removal, cannot be easily implement not in the reduced pressure environment.


An easy to carry out alternative to UV irradiation is the use of much longer wavelength infrared lamps and use heat generated by such lamps (halogen for instance) to remove organics from the solid surfaces in ambient air. It is well known that heat kills viruses and bacteria. Just like in the case of UV cleaning, such IR lamp cleaning was shown very effective in semiconductor processing (e.g. A. Danel, C. L. Tsai, K. Shanmugasundaram, F. Tardif, E. Kamieniecki, J. Ruzyllo, “Cleaning of Si Surfaces by Lamp Illumination”,  UCPSS 2002, Solid State Phenomena, vol. 92, 196-198 (2002)). When properly implemented (temperature, time of exposure) it is also effective in neutralizing viruses and bacteria.


Yet another example how the high demands and experiences of semiconductor processing can be employed in our daily lives

Posted by Jerzy Ruzyllo at 07:55 PM | Semiconductors | Link

Sunday, June 21, 2020

#437 Thirty years ago: June 1990

Papers published in June 1990 in IEEE Transactions on Electron Devices and IEEE Electron Device Letters exemplify significant interest at that time in gallium arsenide (GaAs), and in GaAs-based heterostructures in the variety of transistor configurations (MESFETs, HBTs, HEMTs). At that time GaAs was seen as a possible replacement for silicon in some cutting-edge transistor applications which, as we know now, did not happen. At least to an extent anticipated back then.


What caught my attention among other papers, were the reports on polysilicon and amorphous TFTs (Thin-Film Transistors) which shows growing interest in coming to life at that time active matrix displays technology where TFTs play key role.

Posted by Jerzy Ruzyllo at 03:53 PM | Semiconductors | Link

Sunday, June 14, 2020

#436 Remote college education

Because of the changes extorted by COVID-19, college education is forced to move, at least partially, toward remote learning, with no direct, personal-interactions with university professors and facilities (laboratories).  


While the remote learning may work for some majors, it will definitely not work for the engineering majors. Simply, there cannot be college-level education in the engineering without some kind of the hands-on experiences in the universities’ labs. Certainly not in the case of semiconductor materials/devices engineering. Obvious, but still worth stressing over and over again…

Posted by Jerzy Ruzyllo at 04:58 PM | Semiconductors | Link

Sunday, June 7, 2020

#435 Semiconductor market: inconsistent terminology.

 The reason why business community is using term “Semiconductor Market” in reference to what basically is a “Digital IC Market” is not clear to me. Semiconductor is a material displaying outstanding characteristics, differentiating it from conductors and insulators, which is used in applications far beyond digital (logic and memories) ICs. For some reason, other markets, also based entirely on semiconductor materials are referred to according to what they are. For instance, Analog IC Market, MEMS Market, Photovoltaic Market, LED Market, etc.      


 If this misguided terminology works for business/investments communities, that’s fine. The problem is that it also shows up in some semi-technical writings which should be more precise in using technical terms. For instance, only yesterday I came across an on-line report stating “…transistors, semiconductors, and other electronic components in the future….” Total confusion… What materials are transistors and most of those “other electronic components” made out of?


 By the way, if you are interested in this subject matter and would like to clarify some of the issues raised in this blog, you may want to take a look at my book “Guide to Semiconductor Engineering”. Just a suggestion…


Posted by Jerzy Ruzyllo at 11:58 AM | Semiconductors | Link

›› is a personal blog of Jerzy Ruzyllo. He is Distinguished Professor Emeritus in the Department of Electrical Engineering at Penn State University. With over forty years' experience in academic research and teaching in semiconductor engineering he has a unique perspective on the developments in this technical domain and enjoys blogging about it.

This book gives a complete account of semiconductor engineering covering semiconductor properties, semiconductor materials, semiconductor devices and their uses, process technology, fabrication processes, and semiconductor materials and process characterization.

With over 2000 terms defined and explained, Semiconductor Glossary is the most complete reference in the field of semiconductors on the market today.


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