Semiconductor Manufacturing Rotary Vane Vacuum Pumps & Compressors

Semiconductive material was first discovered as useful electronic material in 1874 with the invention of the AC-DC converter, or rectifier. After this, a series of inventions came in rapid progression, reigning in the era of transistors. These transistors switched on and off, and compiling binary data through a massive number of moving transistors became the new way to collect and store information. These transistors were built by the thousands on singular chips, organized in circuit boards known now as semiconductors. As computers were invented, developed, and streamlined, the need for smaller semiconductors became clear. New methods of semiconductor manufacturing were developed, and the semiconductors became smaller and smaller. The result of this was that more information could be stored, collected, and transferred at an accelerating rate. The issue with this is that the smaller a semiconductor is, the more difficult it is to manufacture. Strict tolerancing must be enforced, meaning more expensive equipment and longer process time. The environment must be entirely clean, and the semiconductor itself must be cleaned and rinsed so that impurities do not affect the tiny semiconductors, as even the smallest scratch will irreversibly damage the semiconductor and hinder its performance or render it useless. Even the cleaners used to clean the semiconductors are specially treated and cleaned. Especially in recent years, leaps and bounds in technique and technology have been made in order to meet the harsh requirements placed on the production of semiconductors.

Semiconductors make use of quartz crystals due to the physical properties that they naturally exhibit. Depending on the cut and size of these crystals, they will begin to vibrate at specific frequencies that can be imposed via electricity. When mechanical stress is applied to these crystals, they begin to oscillate and store electrical charge in a phenomenon known as the piezoelectric effect. This phenomenon is used to the advantage of certain electronic devices, but especially so in the semiconductor, where binary data is stored through the determination of electric charge being charged or not charged per crystal unit.  For this reason, the precise formulation and growth of quartz crystals is important to semiconductor manufacturing and entails a specialized procedure.

To grow quartz crystals of correct sizing and cut, naturally formed quartz crystals are ground and diluted in a solvent, typically water. Naturally occurring crystals contain impurities and defects as they develop in an environment covered in dirt and dust. Once the solution is made, it is placed in a vacuum chamber. The pressure within the chamber is lowered to a controlled degree, which influences the boiling point of the solvent. The solvent evaporates at a rate dependent on the vacuum level and temperature in the chamber, separating the impurities as the solute crystal begins to reform. By the time that the crystals have reformed, the impurities have been removed by the solvent, which has now completely evaporated.

Once the crystals have been formed and used to construct the semiconductor wafer, layers of pad oxide, nitride, anti-reflective coating, photoresist, and glass are placed on top of the wafer. Photoresists are polymers that are soluble when exposed to ultraviolet light. The photoresist is manipulated to shape a pattern on top of the substrate layers below it. Once the shape is formed, it is used as a stencil of sorts, as the carbon hard mask is etched from the top so that every part of it is removed except for that under the photoresist. The rest of the photoresist is stripped off, as well as the anti-reflective coating. The rest of the wafer and layers are etched according to the new shape of the hard mask, and the latter is removed, resulting in a finished semiconductor wafer. These wafers are used in various electronic devices, such as solar cells and computer central processing units.

Etching allows for complex structures to be constructed on miniature scales. Wet etching uses hot liquid etchants to cut into the material on the wafer. Wet etching is extremely versatile and applicable to many different substrates. Dry etching, or plasma etching, is the use of plasma etchants in a pressure-controlled atmosphere to cut into the wafer. Dry etching is significantly more controlled and precise with the cutting, and is useful for more complex circuitry.