RPAGF #314 - Semiconductor technology from scratch
#314 - Semiconductor technology from scratch
A century of navy development couldn't be rushed. After inspecting the Fletcher-class destroyer, Ren Zhong casually resolved a minor conflict between the shipyard and the fleet, subtly revealing his plans.
Professor Liu and Li Changxing were both crucial figures for future development. Making them understand his thinking would simplify many things, preventing unnecessary friction in future collaborations.
Currently, Ren Zhong could accept experimental failures, but he largely rejected unnecessary human interference.
In reality, the main combat power of future warships would come from the command and control systems and weapon systems.
Both of these shared a common technological need: the evolution of radar technology.
Whether it was search radar or fire control radar, both urgently needed further technological advancement to miniaturize the radar and improve its accuracy.
The current aiming error of up to 1000 meters was practically useless for naval warfare.
Therefore, Ren Zhong organized the Doppler radar concept and related technologies and handed them over to the radar team for research.
Due to the involvement of too many disciplines, from materials science to electronics, communication, and even computer calculations, it was only after the breakthrough in transistor computers that they barely possessed the initial ability for spectrum analysis and clutter filtering, completing the first generation of miniaturized Doppler radar.
And the first application of this system was surprisingly in artillery, leading to the completion of artillery aiming radar research!
Of course, this system wasn't small either, requiring three vehicles to tow it. The power generation vehicle and the computer command system for the artillery aiming radar were on one vehicle, while the transmitting and receiving units were on separate vehicles. This was naturally a compromise due to insufficient materials, technology, and craftsmanship. However, with this system, the reaction capability for detecting artillery trajectories could now reduce the position error of artillery positions to around 100 meters within 1 minute.
With the current counterattack capabilities of artillery, this was no different from cheating with a cheat code.
A large number of transistorized new Doppler radars began to demonstrate their initial power.
"It's too difficult. To obtain modern microwave transistors, they must have fine geometric dimensions of micrometers or sub-micrometers. Even if we buy this processing technology, there aren't many good ways to implement it for the time being."
"This manufacturing process requires the development of thin-film epitaxy technology, shallow junction diffusion or ion implantation technology, projection exposure, deep-ultraviolet exposure, X-ray exposure, electron beam exposure, and other micro-fabrication technologies. There are too many prerequisite technologies that need to be developed."
"Moreover, in this regard, the processing of microwave transistors has begun to have a lot of overlap with the processing of integrated circuits."
"It seems that achieving success overnight is impossible. We still have to sort out the development context of each supporting technology and start from scratch."
Looking at the collected data, Ren Zhong had to admit that it was too difficult for a liberal arts student to solve these problems.
Therefore, Ren Zhong didn't plan to do it himself but instead unleashed the power of spending money to buy technical data.
The first thing to be solved was the ion implanter (machine). This equipment also had a long history, dating back to the 1950s in the main world. Semiconductor ion implantation equipment is one of the important equipment in semiconductor manufacturing. It can implant ions into semiconductor materials, thereby changing their conductivity. This process needs to be carried out in a vacuum environment to avoid the influence of impurities on the semiconductor material.
It can be said that semiconductors and subsequent chip manufacturing are inseparable from such equipment.
Specifically, gaseous doping compound raw materials are introduced into the reaction chamber, and an electric field and magnetic field are added to form plasma; after the ion beam is extracted from the reaction chamber, it is accelerated forward by the traction of the electric field and is accelerated twice after passing through the magnetic field to increase the range of the ion beam; the required ion source is selected through a mass analyzer; the ion source passes through a precise ion scanning system to ensure that the doped ions can be uniformly injected onto the entire silicon wafer.
The whole process is very precise. Fortunately, the basic version of this equipment already has relatively popular technology and can be purchased with money.
In terms of the core material of the transistor, the first generation of transistors used germanium to manufacture junction transistors, but this first generation of transistors had a fatal flaw: serious problems would occur when the temperature exceeded 80°C. This was its innate defect. Besides surface cooling, there was no other way, so the power amplification of germanium transistors was very limited.
However, relatively speaking, germanium transistors were relatively easy to implement. Germanium has a lower melting point, which means that its crystals are easier to grow, and producing transistors is relatively easy. Therefore, Ren Zhong still chose this material and quickly realized the first generation of transistor computers. Of course, there were more fans on the back for heat dissipation.
Next, the direction of semiconductor technology research was to overcome silicon transistors!
This was the real mainstream technology that could be used in the 21st century.
Silicon transistors have an NPN structure and need to be manufactured through a grown-junction process. Silicon has a larger bandgap, allowing it to work at higher temperatures (see Table 1). Secondly, it has a significant synergistic effect with its oxide—silicon dioxide (SiO2).
By simply heating silicon in an oxygen-containing atmosphere, a high dielectric strength, electrically insulating SiO2 layer can be formed cheaply. This SiO2 layer is chemically and mechanically very stable, can effectively passivate the surface states of silicon, form an effective diffusion barrier for commonly used dopants, and can be easily etched or deposited on silicon.
Because of its excellent performance, silicon transistors have become the darling of the semiconductor era, dominating most of the semiconductor era. The production of semiconductor silicon wafers alone has become a market of hundreds of billions of dollars, supporting a trillion-dollar semiconductor market.
However, producing semiconductor-grade silicon is extremely difficult. The purity of silicon needs to be refined to an extremely high level, usually exceeding nine 9s (i.e., 99.999999%) before it can be used to manufacture semiconductor transistors. For the present, this is hell-level difficulty.
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The FZ method is another commonly used method for preparing semiconductor-grade silicon. The principle is to add a strong magnetic field around the silicon crystal, melt the silicon material by induction heating, and then form a certain area of melting in the silicon material by controlling electromagnetic induction and movement direction. A wider band-shaped dissolving layer is formed around the molten area, and the dissolving layer is gradually separated from the solid silicon crystal layer above to form a silicon rod. High-purity semiconductor-grade silicon material can be prepared by this method.
Both of these processes are extremely energy-intensive and the equipment is quite complex. Preparing this set of equipment is another systematic project.
Not only is the production method troublesome, but the detection methods are also quite harsh in order to ensure the quality of semiconductor-grade silicon.
Common detection methods for silicon crystals at this stage include thermal absorption method, mass spectrometry, atomic fluorescence method, etc. Among them, the thermal absorption method is one of the most commonly used methods. It can determine the impurity content by testing the amount of gas released when the silicon wafer is heated. Mass spectrometry and atomic fluorescence methods can directly detect the impurity content in silicon wafers, with high sensitivity and accuracy. However, it is clear that these detection methods require a set of precision instruments and equipment to support them.
One problem after another makes Ren Zhong's development in semiconductors extremely difficult and painful.
Of course, he knew that this was inevitable. Now that he wanted to walk the path that others had walked in twenty or thirty years in three to five years, he would inevitably have to pay more hardship, even if he was plagiarizing the homework of the main world, this was not an easy task.
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