Selecting Equipment for the KOH Wafer Etching Process

KOH (potassium hydroxide) etching has become increasingly important as a solution in creating microscopic structures in silicon. The wafer etching process using KOH etching is relatively safe and can be monitored by regulating the bath temperature and doping of the silicon.

The silicon wafer (which is masked with a material that's impenetrable by KOH, most often silicon dioxide or silicon nitride) is immersed in the KOH solution. In order to reach a desired etch rate, the temperature must be controlled. KOH etching is extremely sensitive to temperature variations at temperatures at 60 degrees centigrade and above, that's why accurate control of the temperature is a key factor to produce accurate etching results.

Aside from the variations of temperature, the orientation of the crystal planes in the silicon and the doping of the silicon with boron can also significantly affect the rate and the direction of the etch.

Selecting the right KOH equipment will lead to delivering precise etching results you expected. Modutek supports KOH etching as one of the wafer etching process options within their wet bench process stations.  

Modutek's equipment includes the TFa and TT series Teflon heated tanks which are ideal for supporting KOH etching requirements. The tanks are available in standard size (for single or double capacity) or customized sizes.

The TFa series high-temperature overflow tanks and the TT series static tanks are both PFA Teflon tanks with a Teflon-covered liquid path. It also includes the 360-degree overflow filtration through serration overflow, a condensing Teflon refluxor with Teflon cooling units (optional), an aspirator valve system, a pneumatically actuated auto cover, as well as a Teflon gravity drain.

Learn more about “Selecting Equipment for KOH Wafer Etching Process” by reading the main blog article. You contact Modutek at 866-803-1533 for a free consultation or quote, or send an email to modutek@modutek.com.

How Megasonic Cleaning Improves the Silicon Wafer Cleaning Process

The need for effective elimination of contaminants from silicon microscopic circuits has become increasingly important. Megasonic cleaning, which uses sound waves in the MhHz range generated in the cleaning solution will remove particles as small as 0.1 µm which significantly improves cleaning effectiveness.

The traditional cleaning methods of using harsh chemicals may leave small contaminants in place, and lead to the inferior quality or possibly, even failure of the semiconductor components being produced.

The megasonic cleaning system consists of a high-frequency generator, transducers, and cleaning tank that holds the cleaning solution (such as water or a mild cleaning agent) and the parts to be cleaned. The transducers convert the electric signal (which comes from the generator) to sound waves in the MHz frequency range which travel through the cleaning solution. These sound waves generate microscopic cavitation bubbles in the low-pressure wave troughs. These bubbles will then collapse in the high-pressure peaks, and as a result, they produce tiny jets of water. These resulting jets, when hitting the wafer, will dislodge any particle that adheres on the wafer's surface.

The particles will be carried away by the water currents. There are millions and millions of tiny bubbles which ensure that the silicon wafer is thoroughly cleaned. The bubbles can even penetrate into holes, curves, crevices and other microscopic structures, leaving the surface of the silicon wafer completely cleaned.

Modutek’s Megasonic Cleaning System, developed together with megasonic and ultrasonic technology leader Kaijo Corporation, is a superior alternative to the traditional cleaning methods as it only uses sound waves in the MHz range generated in a water cleaning solution. It can help remove particles down to 0.1 µm in size, to prevent them from affecting the silicon fabrication process. Plus, it improves the overall cleaning performance.

Read more details in the recent article titled “How Megasonic Cleaning Improves the Silicon Wafer Cleaning Process” for additional information. If you have questions, contact Modutek for a free consultation or quote or send them via email at Modutek@modutek.com or call 866-803-1533.

Tips on Selecting an Acid Neutralization System for Your Application

Semiconductor fabrication and research facilities that produce acidic effluents from their industrial processes need to incorporate the use acid neutralization systems. Effluents from industrial processes cannot be legally discharged directly into public sewer systems, but can be processed and disposed of in legally acceptable ways. One way to process them is by altering the pH of acidic effluents waste by-products to legally prescribed ranges. Process engineers and facility managers tend to see waste management operations as a challenging issue to administer and control in terms of cost.

That's why an acid neutralization system that uses automation is the best solution for industrial applications. An automated acid neutralization system is easy to use, cost-effective, and complies with environmental laws and regulations. There are two ways to treat acid effluents: continuous-flow processing or batch processing.

1.      Continuous-flow neutralization system
This is where the stream of influent is treated as it is flowing through a pipeline system, prior to discharge. This method works well in applications where there is a high rate of alkaline discharge or the pH of the influent remains stable from one moment to another.

2      Batch neutralization system
This method works better in dealing with the complex highly acidic influents. Batch systems are suitable for the treatment of processes that cannot be relied upon to produce effluents with unstable pH levels. Since the acidic content tends to change, batches of waste need to be collected and treated separately. Batch neutralization system also excels in the treatment influents that are highly complex, such as those containing heavy metal and fluorides. 

Choosing an automated acid neutralization system minimizes operational errors with its highly computerized monitoring at every stage of the process. These systems feature intelligent, sensor-based checks at every point to alert staff of any need for attention, or problems in the process, when that happens.

Read the complete article “Tips on Selecting an Acid Neutralization System for Your Application” for more details. Contact Modutek for a free quote or consultation at 408-362-2000 to discuss your particular acid neutralization needs.