How Quick Dump Rinsers Improve Silicon Wet Etching Processes

How Quick Dump Rinsers Improve Silicon Wet Etching ProcessesWhen silicon wafers in a wet etching process need rinsing, quick dump rinsers provide fast and effective rinsing of chemicals and particles. In semiconductor fabrication lines such as those of semiconductor manufacturers and research labs, silicon wafers are etched with chemicals. Once the required structures and current paths have been etched into the silicon, the chemicals have to be rinsed off to prevent continued etching. Modutek’s quick dump rinser uses de-ionized water to wash away all traces of chemicals while introducing no new sources of particle contamination. When rinsing is complete, the quick dump rinser drains rapidly. It combines excellent rinsing performance with fast processing and reduced particle counts.

What Makes a Quick Dump Rinser is Efficient and Effective?

Modutek has applied state-of-the-art engineering techniques to design a quick dump rinser that reduces de-ionized water consumption while featuring a short rinsing time and particle reduction. The large trap door and the contoured rinsing vessel shorten dump times and promote laminar flow to rinse away contaminants. The machined dump door has no seals or gaskets that could entrap particles and the smooth polypropylene construction of the tank ensures that it is not a source of new particle contamination.

When the silicon wafers are placed in the rinser, de-ionized water jets rinse the chemicals from the wafer surfaces. The tank fills, bringing the rinsed contaminants to the surface where they leave the tank through the overflow weir. A nitrogen bubbler generates gas bubbles that rise through the water, removing additional contaminants and particles. At the end of the rinse cycle, the trap door at the bottom of the tank opens to quickly drain the water. The whole process is fast and rinsing is complete without added contamination.

Quick Dump Rinsers Provide Substantial Benefits

The use of quick dump rinsers can improve production line performance and output quality. Modutek has designed its quick dump rinser to address wet process manufacturing concerns, including water use, rinsing effectiveness, particle counts and timing. When quick dump rinsers work rapidly, effectively removing chemicals and particles, throughput can increase and the product rejection rate can go down.

Fast rinsing reduces de-ionized water use. Modutek’s 360-degree overflow weir lets contaminated water exit the tank easily and reduces particle entrapment. Dual overhead spray manifolds and low misting nozzles improve rinsing performance with an even distribution of the spray. The nitrogen gas bubbler and tank design promote an even flow around the wafers and the large dump door drains the tank completely in seconds.

Key benefits include reduced costs, fewer product defects and faster production line operation. Reduced de-ionized water use lowers costs and an optional reclaim system can result in additional savings.

The tight packing of semiconductor structures and their decreasing size makes the process more and more sensitive to particle contamination. Even the tiniest particle can cause defects in the final product. Modutek’s quick dump rinser is designed to reduce particle counts and the product failure rate can decrease as a result.

Rinsing is required after many of the wet process production steps and any time saved with a quick dump rinser is multiplied by the number of times rinsing takes place in the semiconductor fabrication production line. The Modutek quick dump rinser delivers these benefits by addressing overall semiconductor manufacturing requirements.

Modutek Works to Improve the Silicon Wet Etching Process for Customers

In addition to quick dump rinsers, Modutek is committed to helping its customers with standard and custom silicon wet etching equipment. The company’s complete wet process product line includes quartz tanks, Teflon tanks and silicon nitride etch baths. Modutek offers free consultation and can ensure that the delivered systems fulfill the needs of its customers.

How Quartz Tanks Improve Wafer Manufacturing

The aggressive chemicals used in wet process wafer manufacturing have to be contained in process tanks that can resist etching and corrosion while remaining inert. Depending on the application, a process may require heating, filtration or the regular addition of chemicals. Quartz tanks from Modutek are made from semiconductor grade flame-polished quartz and are impervious to the acids and bases used in wafer processing. They minimize contamination of the wafers with particles and can be supplied in heated and re-circulating models. The high quality of the bath material along with advanced control strategies developed by Modutek help improve wafer manufacturing performance.

Cleaning Silicon Wafers Using Quartz Tanks

Wet bench processing of silicon wafers consists of fabrication steps such as etching and diffusion with cleaning required in between the steps. Wafers may be masked to etch specific parts of the wafer or to confine diffusion to certain target areas. After each process step is complete, the masking material has to be cleaned off.

Cleaning the wafers completely without contamination is critical because subsequent processing steps are affected if the wafer is not completely clean. With the microscopic architecture of semiconductor components becoming more tightly packed, even a single particle can result in a badly formed structure or conductor. When such malformations are incorporated into the final product, they can be the cause of defective or lower quality semiconductor components.

Specialized Process Controls Help Improve Wafer Manufacturing Results

Specialized quartz tanks from Modutek are based on over 30 years of experience and incorporate features to guarantee safe, reliable operation while delivering excellent wafer manufacturing results. Custom sizes, fast and even heating, reduced downtime and long vessel life help improve manufacturing facility performance and reduce costs. Quartz tank controls allow operators to program reproducible process environments and make sure temperatures and chemical concentrations are consistent. The three areas for which specialized control systems are useful are heating, chemical spiking and filtration.

Modutek high temperature re-circulating baths and constant temperature tanks heat up rapidly with a temperature rise of up to two degrees centigrade per minute. The operating temperature can range from 30 to 180 degrees centigrade and the temperature controller holds the temperature within plus or minus one degree centigrade. Quick heating helps improve throughput and accurate temperature control helps ensure high quality results.

For some chemical processes the concentration of chemicals can change during the process. Periodic spiking restores the chemical concentration to the desired level. Modutek has developed an innovative “bleed and feed” spiking method for the sulfuric acid and hydrogen peroxide (SPM) process.

The hydrogen peroxide of the SPM process decomposes and has to be replenished frequently. For traditional spiking, the mixture has an overall lifespan of only several hours. In Modutek’s clean tank/dirty tank using the “bleed and feed” spiking method, programmable amounts of mixture are drained from the dirty tank and transferred from the clean tank to the dirty tank. Programmable amounts of acid and peroxide are then added to the tanks. This method keeps the mixture fresh and increases the mixture’s lifespan to about one week.

In addition to controls for temperature and concentration, Modutek’s quartz tanks can reduce particle counts and wafer contamination. The quartz re-circulating tank can filter out particles down to 0.2 microns, improving output quality and reducing component failure rates.

Modutek’s quartz tanks are based on more than 30 years of experience and incorporate features to guarantee safe, reliable operation while delivering excellent wafer manufacturing results. Custom sizes, fast and even heating, reduced downtime and long vessel life help improve manufacturing facility performance and reduce costs.

Modutek continues to develop innovative techniques in the construction and use of quartz tanks for semiconductor manufacturing processing. The design of the quartz tanks and the associated advanced controls are a key factor in the production of semiconductor components of the highest quality. With extensive experience working with manufacturers in the development of advanced temperature, concentration and filtration controls, Modutek helps improve wafer manufacturing. Contact Modutek for a free consultation or quote on equipment designed to meet specialized manufacturing requirements.

How Megasonic Cleaning Improves Silicon Wafer Manufacturing Results

Traditional silicon wafer cleaning uses aggressive chemicals to strip wafers and remove particles during semiconductor manufacturing. As semiconductor components such as processors, switches and memory chips become more tightly packed, removing all traces of contamination on the wafer surface becomes important for the production of high quality components and the reduction of component failure rates. Even sub micron particles can block the formation of a conducting path or a key structural component. Ensuring the removal of sub micron particles with traditional cleaning and rinsing has become challenging. Megasonic cleaning can remove even the tiniest particles from silicon wafers and improve process reliability.

How Megasonic Cleaning Works

Cleaning parts with megasonic sound waves in a cleaning solution is a quick and effective way of removing contamination from part surfaces. This cleaning method uses a range of high frequencies with the lower end used for less fragile pieces. The highest frequencies are used for the most delicate parts or parts with soft surfaces.

The sound waves in the cleaning solution create microscopic cavitation bubbles in the wave pressure troughs and the bubbles collapse in the wave peaks. When a bubble collapses, it emits a tiny but energetic jet of cleaning solution that dislodges contaminants and particles from part surfaces. Lower frequencies create comparatively large bubbles with stronger jets while the higher frequencies produce cleaning action with smaller bubbles and lower jet energy.

Because semiconductor components often include very delicate structures and soft layers of deposits on the silicon, only the highest frequencies deliver cleaning gentle enough to avoid structural damage and pitting. Megasonic cleaning takes place with frequencies around the 1 MHz level and higher and delivers effective cleaning without damage. The cleaning method is especially good at dislodging and removing particles as small as 0.1 microns with tiny bubbles breaking the particle’s adhesion to the underlying silicon wafer.

Modutek’s Megasonic Cleaning Solution

Modutek has partnered with Kaijo Shibuya Corporation, a world leader in Megasonic and ultrasonic cleaning technology, to create a line of Megasonic cleaning equipment suitable for use in semiconductor manufacturing. Megasonic cleaning systems can either be turn-key and integrated in fully automated wet bench station, or supplied as individual Megasonic generators and transducers.

Turnkey systems include the cleaning tank with the transducers already mounted while individual components can be integrated in existing semiconductor manufacturing lines. Equipment such as the Spot Shower, Mega Puck and Mega Tube allow operators to direct the Megasonic cleaning action to specific areas in the cleaning tank or on the surfaces of the silicon wafers. Megasonic cleaning reduces sub micron particle counts and can help produce better manufacturing results.

Modutek Megasonic Cleaning Features and Benefits

Systems using high frequency sound waves to clean silicon wafers have to be able to function at several frequencies, depending on the fragility of the parts to be cleaned. At the selected frequency, the megasonic transducers have to deliver enough power to fill the cleaning tank with sound waves, ensuring equal and consistent cleaning without dead spots. Ideally the bath and the transducers should be able to operate at elevated temperatures because some semiconductor manufacturing processes may use heated baths.

Modutek’s Megasonic cleaning systems operate at 950 kHz but frequencies between 200 kHz and 2 MHz are also available. High efficiency generators and full-power transducers deliver up to 1200 W of cleaning power and the systems can operate with bath temperatures of up to 140 degrees centigrade. These features deliver unparalleled cleaning performance without pitting or damage to silicon micro structures. The superior removal rate for particles down to 0.1 microns increases semiconductor component yields, reduces the number of defective components and improves product quality. For a free consultation or quote contact Modutek at 866-803-1533 or email [email protected].