L
Linusthe2nd
Guest
Thank you for the time you spent on this, I learned quite a bit I didn’t know before. I am still curious about how QM was the key to the junction transistor. Would it have been possible for it to have been developed with out QM? And of course nothing here implies that QM creating anything.Linus
Innocente’s statement, “…the chips in your computer and mobile phone couldn’t have been designed or made to work without it”, is not as pertinent for the computer as it is for the mobile phone. The design of an integrated circuit chip has nothing to do with quantum mechanics (QM); the heart of an integrated circuit (IC) consists of a complex arrangement of a vast number of simple “gates” that are all designed using Bollean algebra.
His statement about “couldn’t be made to work without it” is not as easily dismissed because there is some truth to his statement in that QM did open the door to the development (not the design) of the silicon transistor, the basic element of the IC.
Excluding those ideas like “quantum computing” that are highly speculative and as yet not “made to work”, I can think of only three applications of QM: the transistor, the laser, and some medical technologies like MRI. The first transistor “made to work” was a point contact resistor, for which the theory is still not understood, hence it was more of an invention than an application of QM. It was the first transistor put into production…
Soon after Bardeen and Brattain invented the point contact transistor, Schockley used the solution to the Schrodinger wave equation to develop a theory of bipolar junction transistors. Transistors evolved through the grown junction, the alloy, the diffused mesa, and finally the planar transistor. This advance in transistor technology proceeded without QM (name removed by moderator)ut; it was mostly technology with an occasional (name removed by moderator)ut from other scientific fields like solid state diffusion for establishing junctions; metallurgy for purification of silicon, metallization of contacts and wire bonding; chemistry for cleaning and etching of patterns; circuit theory for testing; organic chemistry for the photo sensitive coatings used on the photolithography; etc. All were essential to making transistors work. None of these technologies depended on QM.
QM opened the door that **allowed **the chip to be designed and “made to work”. However without the flood of technology that provided the means for manufacturing chips in large quantities, you (meaning the average guy) would not have a computer or a mobile phone; which is also true if the transistor had not morphed into the integrated circuit.
The design of the IC is based on Boolean algebra and electrical circuit theory. What made IC’s work were several “technological” advances such as: passivation of silicon surfaces, multiple layers of metallization, large diameter silicon wafers, super clean manufacturing environments and defect density control, development of smaller line widths (integration); computer controlled testing; and wafer stepper lithography. etc. Again these are QM free technologies.
However I am not about to dismiss QM completely, because the laser, a QM invention, has made it possible to increase integration to allow the manufacture of smart phones. When I left the industry 19 years ago, the state of the art of producing line widths, the minimum useable feature, was 250 nanometers. The ability to manufacture such tiny features was limited by the wave length of the ultraviolet (uv) light that was used for photolithography and the capability of the optics to resolve the resulting line width on the surface of the silicon wafer. The 250 nm was the limit for the uv light supplied by mercury vapor lamp and there was talk about going to x-ray wave lengths to produce smaller line widths. It was possible to make personnel computers with the 250nm technology, but I don’t believe it was possible to produce the kind of smart phones now available. Fortunately, it was found that smaller wave lengths of light in the uv range were available using Excimer lasers that translated in a reduction of line width features to lower than 45 nanometers obviated the need for x-ray lithography.
QM was used in the basic design of the junction transistor, but not the MOS transistor, the element with which integrated circuits are made. The MOS transistor was invented, the theory came later.
I have little doubt that the MOS transistor would eventually be discovered without QM theory, but it would have been discovered in one of the research laboratories associated with the great Semiconductor Companies much later in our history than it was. Once the MOS transistor was invented, the integrated circuit and all that it led to would have followed.
I hope this was something close to what you were looking for. If not I am willing to share my experience to answer any specific question you might have.
Yppop
Linus2nd