Semiconductors are unique substances, which, under different conditions, can act as either conductors or insulators of electricity. Semiconductor processors turn one of these substances—silicon—into microchips, also known as integrated circuits. These microchips contain millions of tiny electronic components and are used in a wide range of products, from personal computers and cellular telephones to airplanes and missile guidance systems.
To manufacture microchips, semiconductor processors start with cylinders of silicon called ingots. First, the ingots are sliced into thin wafers. Using automated equipment, workers or robots polish the wafers, imprint precise microscopic patterns of the circuitry onto them using photolithography, etch out patterns with acids, and replace the patterns with conductors, such as aluminum or copper. The wafers then receive a chemical bath to make them smooth, and the imprint process begins again on a new layer with the next pattern. A complex chip may contain more than 20 layers of circuitry. Once the process is complete, wafers are then cut into individual chips, which are enclosed in a casing and shipped to equipment manufacturers.
The manufacturing and slicing of wafers to create semiconductors takes place in cleanrooms—production areas that are kept free of all airborne matter because the circuitry on a chip is so small that even microscopic particles can make it unusable. All semiconductor processors working in cleanrooms must wear special lightweight outer garments known as "bunny suits". These garments fit over clothing to prevent lint and other particles from contaminating the cleanroom.
There are two types of semiconductor processors: operators and technicians. Operators start and monitor the equipment that performs the various production tasks. They spend the majority of their time at computer terminals, monitoring the operation of equipment to ensure that each of the tasks in the production of the wafer is performed correctly. Operators may also transfer wafer carriers from one station to the next, though the lifting of heavy wafer carriers is done by robots in most new fabricating plants.
Technicians are generally more experienced workers who troubleshoot production problems and make equipment adjustments and repairs. They take the lead in assuring quality control and in maintaining equipment. They also test completed chips to make sure they work properly. To keep equipment repairs to a minimum, technicians perform diagnostic analyses and run computations. For example, technicians may determine if a flaw in a chip is due to contamination and peculiar to that wafer, or if the flaw is inherent in the manufacturing process.
Work environment. The work pace in cleanrooms is deliberately slow. Limited movement keeps the air in cleanrooms as free as possible of dust and other particles, which can destroy microchips during their production. Because the machinery sets the operators' rate of work, workers maintain a relaxed pace. Although workers spend some time alone monitoring equipment, operators and technicians spend much of their time working in teams.
Technicians are on their feet most of the day, walking through the cleanroom to oversee production activities. Operators spend a great deal of time sitting or standing at workstations, monitoring computer readouts and indicators.
The temperature in the cleanrooms must be kept within a narrow range and is generally comfortable for workers. Although bunny suits cover virtually the entire body, their lightweight fabric keeps the temperature inside fairly comfortable. Entry and exit of workers from the cleanroom are controlled to minimize contamination, and workers must be reclothed in a clean bunny suit and decontaminated each time they return to the cleanroom.
Several highly toxic chemicals are used at various points in the process of manufacturing microchips. Workers who are exposed to such chemicals can be seriously harmed. However, fabrication plants are designed with safeguards to ensure that these chemicals are handled, used, and disposed of without exposing workers or the surrounding environment. Toxic chemicals are applied to wafers by computer-controlled machine tools in sealed chambers, and there is normally little risk of workers coming into contact with them.
Semiconductor fabricating plants operate around the clock. Night and weekend work is common. In some plants, workers maintain standard 8-hour shifts, 5 days a week. In other plants, employees are on duty for 12-hour shifts to minimize the disruption of cleanroom operations brought about by changes. Managers may also allow workers to alternate schedules, thereby distributing the overnight shift equitably.
| 1. | Manipulate valves, switches, and buttons, or key commands into control panels to start semiconductor processing cycles. |
| 2. | Maintain processing, production, and inspection information and reports. |
| 3. | Inspect materials, components, or products for surface defects and measure circuitry, using electronic test equipment, precision measuring instruments, microscope, and standard procedures. |
| 4. | Clean semiconductor wafers using cleaning equipment, such as chemical baths, automatic wafer cleaners, or blow-off wands. |
| 5. | Study work orders, instructions, formulas, and processing charts to determine specifications and sequence of operations. |
| 6. | Load and unload equipment chambers and transport finished product to storage or to area for further processing. |
| 7. | Clean and maintain equipment, including replacing etching and rinsing solutions and cleaning bath containers and work area. |
| 8. | Place semiconductor wafers in processing containers or equipment holders, using vacuum wand or tweezers. |
| 9. | Set, adjust, and readjust computerized or mechanical equipment controls to regulate power level, temperature, vacuum, and rotation speed of furnace, according to crystal growing specifications. |
| 10. | Etch, lap, polish, or grind wafers or ingots to form circuitry and change conductive properties, using etching, lapping, polishing, or grinding equipment. |
| 11. | Load semiconductor material into furnace. |
| 12. | Monitor operation and adjust controls of processing machines and equipment to produce compositions with specific electronic properties, using computer terminals. |
| 13. | Count, sort, and weigh processed items. |
| 14. | Calculate etching time based on thickness of material to be removed from wafers or crystals. |
| 15. | Inspect equipment for leaks, diagnose malfunctions, and request repairs. |
| 16. | Align photo mask pattern on photoresist layer, expose pattern to ultraviolet light, and develop pattern, using specialized equipment. |
| 17. | Stamp, etch, or scribe identifying information on finished component according to specifications. |
| 18. | Operate saw to cut remelt into sections of specified size or to cut ingots into wafers. |
| 19. | Scribe or separate wafers into dice. |
| 20. | Connect reactor to computer, using hand tools and power tools. |
| 21. | Mount crystal ingots or wafers on blocks or plastic laminate, using special mounting devices, to facilitate their positioning in the holding fixtures of sawing, drilling, grinding or sanding equipment. |
| 22. | Attach ampoule to diffusion pump to remove air from ampoule, and seal ampoule, using blowtorch. |
| 23. | Measure and weigh amounts of crystal growing materials, mix and grind materials, load materials into container, and monitor processing procedures to help identify crystal growing problems. |
| 24. | Locate crystal axis of ingot, and draw orientation lines on ingot, using x-ray equipment, drill, and sanding machine. |
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