How the IPA Vapor Dryer Provides Superior Wafer Processing

After etching and rinsing, an IPA (isopropyl alcohol) vapor dryer can produce dry silicon wafers without watermarks and limited particle adders. IPA drying is also known as Marangoni drying, relies on the Marangoni effect of low surface tension of IPA compared to water.

When IPA vapor is introduced into the drying chamber in an IPA vapor dryer, a surface tension gradient is established between the IPA and water on the surfaces of the silicon wafers. The surface tension gradient causes water to flow off the silicon wafers and they are left clean and dry. In addition, the slow drain of water feature also helps to minimize particles that contaminate the wafer surfaces. It results to clean wafers after a final etch and before the next semiconductor manufacturing step.

IPA vapor dryers are particularly suitable for drying thin, delicate silicon wafers. It dries the wafers without moving them, unlike in other drying methods, and they are not subjected to any stress. As a result, any damage is minimized while the drying performance remains excellent.

The IPA vapor dryer improves wafer processing after the final hydrofluoric acid etching. The wafer has to be rinsed with de-ionized water and dried before undergoing the next manufacturing step. Providing a clean wafer with a low particle count is crucial at this stage because the following process steps will be affected by the presence of leftover contamination or particles. Because IPA vapor dryers remove water from the water surface and reduce particle counts with the Marangoni effect, the IPA vapor dryers improve wet processing equipment results and ensure higher quality output.

The complete article, “How the IPA Vapor Dryer Provides Superior Wafer Processing,” goes into further detail. If you have questions, or you would like to set up a free consultation, contact Modutek at 866-803-1533 or email Modutek@modutek.com.

Specialized Wafer Etching for Critical Wet Processing Applications

specialized-wafer-etching-for-critical-wet-processing-applications2The success of the wet process application depends on selecting wet bench processes designed for the tasks at hand. Specialized equipment can support different etching and cleaning processes and can be used to make sure that the process selected can fulfill specific application requirements.

Depending on the etching or the cleaning task to be performed, specific wafer etching processes are needed. For example, the fabrication of solar cells has different requirements compared to the requirements for the creation of microscopic structures for a processor. Here are the following major process characteristics which can impact wafer manufacturing:

1)     Low particle count – these characteristics are especially critical for the smallest structures. A high particle count can cause defects in micro structures, which result in higher failure rates during final testing.

2)     Etching speed – If the goal is to remove substance as fast as possible, high-speed etching can be used, but with this process, precision can be compromised.

3)     Selectivity – for highly selective processes, the substrate material is not affected by the etchant while the material to be removed is etched rapidly.

4)     Precise control – this characteristic becomes more critical as the dimensions of the micro-structures decrease and the packing of components becomes denser.

5)     Undercutting – It compromises control precision but can be minimized or eliminated with anisotropic etching by selecting the proper process and the orientation of the silicon crystal planes.

Choosing the right process to deliver the etching characteristics required will have a high impact on wafer etching process line performance. Key performance indicators that include product rejection rates, throughput, downtimes and operating costs can vary greatly, depending on the best match of the process to application.

Modutek’s wet process stations are specialized for different processes and also guarantee safe and reliable operations. The company offers a complete line of wet process stations and can deliver solutions for general etching and cleaning, as well as for specialized applications. Modutek’s equipment supports several processes, including:

  • Piranha etch – removes organic material from substrates and is often used to remove photoresist from silicon wafers. Modutek can determine whether piranha etch is a good fit for a specific application.
  • KOH etching process – the etch rate is controlled by changing the temperature of the KOH etching (potassium hydroxide). Modutek supports this process with baths that provide tight temperature control.
  • Buffered Oxide Etch (BOE) – is used primarily to etch silicon dioxide and silicon nitride. Modutek supports this process with its sub-ambient filtered baths.
  • Ozone resist strip – it cleans organic residue while reducing particle count. Modutek supports this with the ozone strip process which does not use chemicals.

For more details about this topic, read the complete article “Specialized Wafer Etching for Critical Wet Processing Applications”. If you would like to set up a free consultation to discuss any questions you may have, contact Modutek at 866-803-1533 or email to Modutek@modutek.com.

How Quartz Tanks Improve Wafer Manufacturing

how-quartz-tanks-improve-wafer-manufacturing2Chemicals used in wet process wafer manufacturing need to be contained in process tanks that can resist etching, corrosion and remain inert. In some applications, a process may require heating, filtration or the regular addition of chemicals. Quartz tanks are made from semiconductor grade flame-polished quartz and are impervious to the acids and bases used in wafer processing. They minimize contamination of wafers from particles and can be supplied in heated and re-circulating models.

Wet bench processing of silicon wafers consists of fabrication steps such as etching and diffusion with cleaning required in between the steps. The wafers are “masked” to etch specific parts of the wafer to confine diffusion to certain target areas. Once each process step is done, the masking material must be cleaned off.

Cleaning the wafers completely without contamination is crucial. When the wafer is not clean and still has contaminants, even a single particle can result in a badly formed structure or conductor. When such malformations are incorporated into the final product, it can result in defective or lower-quality semiconductor components.

Modutek offers specialized quartz tanks that are made from semiconductor grade flame-polished quartz and are impervious to the acids and bases used in wafer processing. Quartz tank controls allow operators to program reproducible process environments and make sure temperatures and chemical concentrations are consistent. Heating, chemical spiking, and filtration are the three important areas for which specialized control systems are useful.

Heating – Modutek’s high-temperature re-circulating baths and constant temperature tanks heat up rapidly with a temperature rise of up to two degrees centigrade per minute. Quick heating helps improve throughput and accurate temperature control helps ensure high-quality results.

Chemical spiking – Periodic spiking restores the chemical concentration of the chemicals to the desired effect. Modutek has developed an innovative “bleed and feed” spiking method for the sulfuric acid and hydrogen peroxide process.

Filtration – Modutek’s quartz tanks can also 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.

The complete article, “How Quartz Tanks Improve Wafer Manufacturing” explains more details. If you have questions and would like to set up a free consultation, contact Modutek at modutek@modutek.com or call 866-803-1533.

How Megasonic Cleaning Improves Silicon Wafer Manufacturing Results

Semiconductor components that include processors, switches and memory chips have become so miniaturized, that even sub-micron foreign particles can block the formation of a conducting path or other key structural components. That is why removal of sub-micron particles during the manufacturing process is crucial to avoid defective products. These particles are usually removed by traditional cleaning and rinsing using aggressive chemicals. However, megasonic cleaning is the better alternative option in cleaning silicon wafers because it can remove even the tiniest particles.

Megasonic cleaning uses megasonic sound waves to remove contamination from surfaces of parts being cleaned. The sound waves in the cleaning solution create microscopic bubbles in the wave pressure troughs and collapse them in the wave peaks. When a bubble collapses, it discharges a tiny but powerful and energetic jet of cleaning solution that dislodges contaminants and particles from part surfaces. Modutek has partnered with Kaijo Shibuya Corporation, a world leader in Megasonic and ultrasonic cleaning systems, to create a line of Megasonic cleaning equipment suitable for use in semiconductor manufacturing.

Megasonic cleaning uses a wide range of frequencies. The right selection of frequencies is the key to optimum cleaning performance. Lower frequencies are used for less fragile devices, while higher frequencies are suitable for gentle cleaning of the more delicate parts or parts with soft surfaces.

And because semiconductor components often include very delicate structures and soft layers of deposits on the surface, only the highest frequencies deliver gentle cleaning to avoid damage and pitting to these fragile structures.

Modutek’s Megasonic cleaning system can clean at frequencies between 200 kHz and 2 MHz but generally operates at 950 kHz. The system delivers up to 1200 W of cleaning power and can operate with bath temperatures of up to 140 degrees centigrade. The system offer superior performance and can removal rate for particles down to 0.1 microns which improve semiconductor component yields, reduces the number of defective components and improves product quality.

For more details read the complete article “How Megasonic Cleaning Improves Silicon Wafer Manufacturing Results”. If you have questions after reading the article, or would like to set up a free consultation, contact Modutek at modutek@modutek.com or call 866-803-1533.

Customized Table Top Chemical Process Tanks

Table top chemical process tanks are more ideal for smaller operations and specialized applications that require semiconductor fabrication capabilities.

Research labs, universities and start-up companies can use table top chemical process tanks to produce single parts or low-volume components for either proof of concept or prototype testing. Small chemical process tanks provide the capability to fabricate such products in a customized unit designed for the specialized applications.

Table top chemical process tanks for specialized output are heavily customized to reflect their unique purposes. Tank size, chemicals used, controls, heating and circulation are all adapted to the particular use. Since Modutek designs and builds all of its wet bench equipment in-house, the company is ideally suited to provide the customization required for this special application.

Features and benefits of the Modutek Table Top Systems:

  • Installation – Mobile tanks with customized shapes and sizes.
  • Circulation – Tanks can be static or fitted with overflow circulation and filtration.
  • Heating – Tanks are ambient temperature or temperature controlled. For heated tanks, the operating temperature is 30 to 100 degrees centigrade.
  • Process – The tanks are usually Teflon tanks for KOH and related wet purposes.
  • Wafer Holders – The systems usually come with standard carriers sizes for single or double capacity, as well as custom-made sizes.
  • Controls – There are process controllers available to handle temperature and timing.

Modutek can assemble customized table top chemical process tanks with the required features exactly as specified by customer to meet their requirements. Benefits include reliable and safe operation, consistent process variables and repeatable outputs and results. For more details read the complete article titled “Customized Table Top Chemical Process Tanks”. Contact Modutek for a free quote or consultation to discuss your specific chemical process application requirements.

Selecting the Right Acid Neutralization System for Your Application

An acid neutralization system treats the discharge from the semiconductor wet process fabrication facilities, as well as other industrial processes, to make the liquids environmentally safe for disposal.

The right system for an application will add alkaline chemicals to the acidic solution and increase the pH close to the neutral reading of 7, while recording process data to ensure regulatory compliance. If the acid is untreated, releasing it would be environmentally hazardous and pollute waterways. Governments have imposed regulations on the procedures required to dispose of industrial waste.

An acid neutralization system treats and measures the acidity of wastewater as it exits the production line. Depending on the process, a suitable neutralizing chemical is added to reduce the acidity. The sensors verify that the pH level of the wastewater has been reduced due to neutralization. That pH level should be in compliance with the applicable government regulations before the liquid can be released.

Depending on the type of operation, an acid neutralization system can be selected in either continuous flow or in batches:

1) Continuous flow neutralization
This applies to the continuous flow acid neutralization systems which have a continuous addition of neutralizing chemicals. There is only a slight variation that is easily controlled and monitored. The flow can be from a few gallons to several hundred gallons per minute. Discharges and their characteristics are recorded on a digital chart recorder.

2) Batch neutralization
In this type of neutralization system, the batches of waste chemicals often need extensive treatment and may require different neutralizing chemicals to meet the allowed discharge pH levels. The system takes the pH level reading and then adds the necessary chemicals to verify the correct pH level has been reached.

Modutek’s acid neutralization systems are fully automated and are available in batch neutralization or continuous flow designs. The compact design allows these systems to fit into available space and can be customized for specific applications.

For more details read the complete article, “Selecting the Right Acid Neutralization System for Your Application”. Contact Modutek at 866–803–1522 or email Modutek@modutek.com to schedule a free consultation to discuss your specific requirements or get a free quote.

5 Important Things to Know When Buying Wet Bench Stations

Because of the complicated nature of semiconductor manufacturing, wet benches need to be customized to meet specific requirements for a specific application.

Before focusing on the process-specific requirements, there are general questions that should be answered. They include the level of automation, whether stainless steel solvent stations are required, whether a chemical delivery system is needed and whether any special options for rinsing and drying would be beneficial. Following this structured approach helps with selecting the best wet process station configuration and with integrating special equipment within the wet bench station.

1) Automated Wet Bench Stations
Modutek’s line of wet bench stations can be manual, semi-automatic or fully automated. You get the most benefits from using fully automated stations since they can run batches without operator intervention and provide excellent repeatability if the same product is manufactured multiple times. The use of Modutek’s proprietary software will help increase throughput and yield.

2) Stainless Steel Solvent Stations
Modutek’s stainless steel solvent stations are available in the manual, semi-automatic and fully automated stations as well as in dry-to-dry configurations. Solvent stations are designed to satisfy fire safety standards that are needed in solvent applications.

3) Chemical Delivery System
Modutek’s chemical delivery systems help avoid spills and make tracking of chemical neutralization and disposal easier. The company can also customize the system’s design to exactly meet the needs of a customer’s application.

4) Rinsing and Drying
When an etching or cleaning process step is complete, the wafers must be rinsed and dried without leaving any contaminants. Modutek’s IPA dryer combines rinsing and drying in one station while the quick dump rinser improves the process efficiently.

5) Special Etching or Cleaning Equipment
Some semiconductor fabrication and research facilities may require specialized wet bench equipment for specific etching or cleaning process steps. For this reason, Modutek can incorporate specialized equipment such as the Vacuum Metal Etcher which is designed to etch aluminum layers with high precision and remove hydrogen bubbles when they are created.

For more details read the complete article “5 Important Things to Know When Buying Wet Bench Stations”. Contact Modutek by email at Modutek@modutek.com or call 866-803-1533 to schedule a free consultation to discuss your needs or get a free quote.