Because semiconductor manufacturing is made up of a large number of steps, silicon wafer processing often includes unique requirements. Standard equipment may be suitable to some extent, but using custom equipment adapted to the particular process can improve production line performance. Customization of the physical characteristics of the system, the software, the degree of automation and the process components can impact how well the silicon wafer processing equipment works. An experienced supplier of wet processing equipment can advise customers regarding possible customization and follow up with specific equipment suggestions.

Physical Customization of Wet Process Equipment

Semiconductor manufacturing equipment often has to fit into a defined space or is retrofitted into an existing production line. In either case, the dimensions have to be customized to fit the available space. Modutek can build processing stations and tanks with special dimensions to fit and can arrange components for less depth or less length as required. Because Modutek designs and builds all its own equipment, the company is capable of changing the dimensions of its standard products to fit customer requirements.

Customized Software for Special Calculations

The Modutek SolidWorks Flow Simulation and Simulation Professional software allows customers to accurately calculate chemical dosages and to track chemical usage. Custom installations may require special calculations and the software may have to be adapted to calculate and track custom chemical use. Modutek writes all its own software and can therefore customize and adapt the program code. Customers can rely on Modutek to maintain and support the non-standard software and make sure it works the way the customer wants.

Automation With Customized Characteristics

Modutek’s standard wet processing equipment is available in fully automated, semi-automated or manual versions but customers may require some automated functions while other functions remain manual or semi-automatic. Prototypes often rely on manual controls to define basic process parameters. Then the process is optimized in semi-automatic operation while eventually running in fully automatic mode when in full production. Existing product manufacturing may require only full automation but the manufacturing process may need operators to execute some manual functions.

Depending on the customer’s manufacturing needs, Modutek can design automation combining manual and automatic controls as specified by the customer. The automatic process may run until operator intervention is required to execute a command or check a specific condition. Modutek can adapt its systems to meet such special automation needs.

Customized Process Components and Subsystems

Process components and subsystems may include chemical delivery, baths or tanks, wafer handling and wafer drying. Modutek can integrate some of these functions into a single unit or place separate units into a custom arrangement. For example, a chemical delivery station can have local or remote tanks and can be placed behind the processing stations to save space. An IPA vapor dryer can include de-ionized water rinsing and vapor drying in one unit. With the company’s experience as a leading wet bench manufacturer, Modutek can design custom arrangements that carry out the required wet process functions within the parameters set by the customer.

Modutek’s Customizations Improve Process Performance

Modutek has a complete line of standard wet process stations, all designed and built in house. For new customized projects, the custom system is evaluated for special requirements and possible solutions. Modutek then works closely with the customer to ensure that the chosen customizations reflect the special process requirements and will produce the expected results.

When Modutek builds such custom systems, they choose customization over standard systems because the customization will improve overall performance. Improvements can include higher throughput, better output quality and lower costs. Working transparently with the customer, Modutek can demonstrate how its proposals will produce better results and ensure that the finished system meets expectations.

Key Quartz Tank Characteristics for Silicon Wafer Processing

Silicon wafer processing involves etching the wafers to produce microscopic structures and cleaning the wafers in preparation for further process steps. Corrosive chemicals such as hydrochloric acid, sulfuric acid and hydrogen peroxide are used for the etching and cleaning process. Tanks made of quartz are not affected by these aggressive chemicals because quartz is a crystalline material made up of silicon and oxygen atoms held tightly in a crystal lattice. Semiconductor-grade quartz such as used in the Modutek quartz tanks is especially pure, reducing the possibility of contamination.

In addition to resisting corrosion by aggressive chemicals, quartz tanks are stable at high temperatures. Some etching processes work better at temperatures up to 180 degrees centigrade and the quartz crystal lattice remains intact at much higher temperatures. Modutek quartz tanks are designed to take advantage of the chemical and temperature stability of the quartz tanks to provide an ideal vessel for containing the silicon wafer etching and cleaning processes.

The Importance of Reduced Contamination

The use of high-purity flame-polished quartz in silicon wafer processing tanks ensures that there are few non-quartz substances in the crystal lattice and on the polished surface of the tanks. The possibility of contamination by the tanks is reduced to a minimum. Such contamination of the silicon wafers can affect the semiconductor products made from the wafers.

The functionality of semiconductor components relies of microscopic structures and current paths created on the silicon wafer. When a tiny particle or other contaminant interferes with the etching of these structures, the final semiconductor product may be defective or of inferior quality. The rejection rate for finished semiconductor products is heavily influenced by the presence of particles or other contaminants. Reducing the particle count by using high-quality quartz tanks reduces the number of defective components and increases output quality.

Why Precise Temperature Control Gives Improved Process Results

Depending on the chemicals used, a higher temperature may increase the etch rate and reduce processing times. While a high etch rate may be desirable, the amount of etching that takes place still has to be tightly controlled because the amount of etching determines the size and shape of the microscopic structures in the silicon. On the one hand, exactly the right amount of etching has to take place before the process finishes, and on the other hand, if the same process is run again, the amount of etching has to be the same.

The two main factors influencing the etch rate are chemical concentration and temperature. Modutek’s process controls ensure that the right chemical concentration is maintained and the quartz tank temperature controls keep the process at exactly the right temperature. Modutek’s quartz tank temperature controller can keep the temperature constant within plus/minus 1 degree centigrade for precise etching control and excellent repeatability from one batch to the next.

For improved silicon wafer processing, process tanks have to be free of contamination and have to accurately reproduce process conditions. With Modutek’s high temperature quartz tanks, reduced contamination during etching and cleaning of silicon wafers is ensured and the temperature controls of the tanks provide precise settings during the process and for subsequent batches.

SEMICONDUCTOR WET PROCESS EQUIPMENT AND WET BENCH MANUFACTURER

Monthly Archives: November 2020

How Customized Equipment Improves Silicon Wafer Processing