Commercial Opportunities for MEMS Technology

Micro-electro-mechanical systems (MEMS), is a technology that involves the use of microscopic devices that range in size from several millimeters to less than one micron. MEMS usually have both electrical and mechanical functions and often include parts that can move in response to several factors such as process conditions, commands from outside the structure, or commands from integrated electronics.

Initially used in the automotive industry, the use of MEMS has expanded to other industries that include medical and optical fields. The MEMS sensors are comparatively inexpensive to produce but they perform better than the corresponding macroscopic sensors, which have been taken over by MEMS.

As MEMS fabrication methods became advanced, the systems were able to incorporate additional functions and different structures.

MEMS are manufactured by a process which is similar to that used to produce microelectronics. For the silicon-wafer based MEMS, the wafers are masked, etched, and cleaned in multiple steps. Silicon wet etching is the primary method used in manufacturing MEMs and offers a number of advantages.

Silicon wet etching using KOH (potassium hydroxide) is also known as KOH etching. It offers a number of advantages including low cost, reliability, as well as safe, quick and precise etching. This process can be repeated and controlled by changing the temperature, the KOH concentration, the crystal plane orientation of the silicon and the doping concentration.

Modutek offers a wide variety of wet bench equipment that supports KOH etching. Its KOH silicon etching tank is designed, developed, and manufactured in-house and can be designed according to the client's specific wet bench applications. The tanks are specially developed and manufactured to reduce impurities. The resulting process tanks deliver unparalleled performance and high-quality output. Custom installations for existing wet bench equipment can also be done.

For more details on KOH etching options for MEMS technology read the article titled “Commercial Market Opportunities for MEMS Technology”. If you have questions or would like a free consultation or quote contact Modutek at Modutek@modutek.com.

Choosing the Right Chemical Delivery System for Your Application

Semiconductor manufacturers and research labs need a safe way to handle and supply chemicals to the points where they are being used, so choosing the right chemical delivery systems are crucial.

Chemical storage and system performance are key factors in selecting chemical delivery systems. They have to receive the chemicals in large volumes, store them safely and conveniently, supply them to the point of use in the exact required amounts and composition, neutralize them as needed and discard them safely and properly. Custom configurations, fast chemical changes, and control options may also be important.

Ideally, a chemical delivery system enhances facility of manufacturing line performance by increasing throughput and producing better quality results. It can be done by minimizing human intervention that will prevent the possibility of errors and slowdown of the process. When chemicals are supplied to the point where they should be used, the facility can operate at optimal precision and efficiency.

Modutek's advanced chemical delivery systems provide all the required features and functions discussed above. Large tote containers hold chemicals are designed to reduce frequent drum changes while the large volumes of chemicals are used. A 55-gallon drum system is ideal for holding the chemicals in smaller volumes. Both storage systems allow for quick chemical changes and feature Teflon-lined fluid paths with leak detection and sensing of up to four levels. The systems also have touch screens which display the automated chemical deliveries as well as the status of other key components like valves, pumps, and alarms.

These systems also use software and components that are designed and produced in Modutek's own facility, ensuring exceptional service for all its equipment. Modutek can also develop custom designs for the client's specialized requirements. Read our recent article titled “Choosing the Right Chemical Delivery System for Your Application” and then call Modutek at 408-362-2000 if you have questions or would like to discuss your application needs.

Using KOH Etching for Batch Processing

Etching baths with varying concentrations of potassium hydroxide (KOH) and controlled temperatures are used to create microscopic structures on silicon wafers. Semiconductor manufacturing and research facilities usual prefer the KOH etching process because it provides controlled and uniform etching results with a high degree of precision. In addition, it’s also comparatively safe.

The silicon surface is masked to enable etching and the creation of cavities in specific areas, based on the layout of the final semiconductor product. The etch rate can be precisely controlled by adjusting the bath temperature and the levels of KOH. The KOH etching is also influenced by the following:

·         The presence of atomic defects in the silicon crystal

·         The lattice planes of the crystalline silicon

·         Boron doping of the silicon

·         Natural impurities

The oriention of the lattice planes in a particular direction can also influence and control the direction of the etching and the shape of the cavities created in silicon. Also boron doping can be used to stop etching in a specific direction. These along with the mask are factors that permit the creation of cavities in required shapes and orientations.

The advantages of KOH etching include:

·         Safe

·         Easy to handle

·         Rapid etching

·         Excellent reproductivity

·         Cost-effective

·         Provides high precision when process variables are strictly controlled

Modutek’s KOH Etching process equipment includes PFA Teflon tanks, circulation and filtering systems as well as cassette handling equipment. Modutek also provides customized equipment for a particular application, by size, capacities, and controls. These may include the KOH processing tank, the recirculating system, and the silicon wafer handling. Modutek uses the latest state-of-the-art technology to provide high accuracy and exceptional output quality.

For more details read the complete article titled “Using KOH Etching for Batch Processing” and and contact Modutek if you have questions or would like to discuss your particular application requirements.

Wet Processing System for Solar Cell Manufacturing

Solar cell manufacturing facilities and research labs use wet processing equipment to etch and clean solar cell silicon wafers. Removal of wafer saw damage, silicon wafer texturing, chemical polishing and cleaning of the wafers with reliable and safe wet processing systems is an important factor to increase productivity and high quality output.

Modutek offers the latest wet bench and ozone cleaning technology to meet client requirements, whether they want to purchase standard systems or customized solutions. Modutek provides wet processing systems and equipment to a number of manufactuers in the solar cell industry.

Silicon Wafer Saw Damage Removal
When solar cell silicon wafers are cut they the surface will be damaged with an uneven crystal structure and damaged crystal lattice. These wafers are soaked in an etching bath that lifts a thin layer of damaged crystal, leaving a smooth uniform surface. Modutek’s wet processing equipment provides high throughput and accurate controls for this process.

Silicon Wafer Texturing
Solar cell silicon wafers absorb light and convert it into electricity more effectively when their front surface is etched with a microscopic texture.

For monocrystalline silicon, an etching bath lifts small pyramid shapes from the silicon's surface, which leaves a smooth, even consistent texture. Multi-crystal silicon, on the other hand, can be etched in the same manner, but the result is not as smooth because of crystal's different orientation. Available alternative solutions include ion-etching and masks.

Chemical Polishing
After the front, the rear side and the edges of the cell are polished by placing it in an etching bath. Polishing them improves the internal light reflection.

Ozone Pre-Cleaning
The cutting of silicon wafers with a wire saw uses a slurry applied to the wires, leaving the wafers contaminated with the slurry. To clean them, Modutek's Ozone Cleaning Process uses ozone dissolved in a mild solution. This cleaning process yields efficient cleaning at a lower cost.

Modutek’s wet Processing System is an ideal solution for solar cell manufacturers. Discover how Modutek can assist your company by reading our complete article titled “Wet Processing System for Solar Cell Manufacturing. Contact Modutek for a free quote or consultation to discuss which equipment to use for your application.