How the Ozone Cleaning Process Improves Silicon Manufacturing Yields

How the Ozone Cleaning Process Improves Silicon Manufacturing YieldsA process that uses ozone with water or with a mild acid can clean, strip and etch wafers more rapidly and at lower cost than traditional processes. Modutek’s proprietary Advanced Ozone Cleaning Process eliminates the use of expensive chemicals while improving process performance and reducing environmentally harmful waste.

Modutek provides custom designed equipment to meet the specific requirements of customers and offers an ozone cleaning process as a solution for better silicon wafer manufacturing yields. The patented technology can replace traditional methods that use expensive chemicals and high temperatures with a room-temperature process that is environmentally friendly.

How the Ozone Cleaning Process Works

Modutek’s ozone cleaning process provides cleaner silicon wafers with reduced particle counts. For example, in Modutek’s DryZone solvent gradient dryer, the patented process rinses substrates with deionized water to remove water-miscible inorganic impurities and then exposes them to ozone in an ozone chamber. All traces of organic materials are converted to carbon dioxide. The resulting substrate surfaces are free from particles, moisture and trace organic materials and are stable hydrophilic surfaces.

For silicon wafers, the surfaces are Si-O terminated. If hydrophobic, Si-H terminated surfaces are required, a ten second post-ozone process can complete a conversion. Because the dryer uses reactive chemistries, it is particle-reducing rather than just particle-neutral.

In Modutek’s Organostrip process, wafers are exposed to an ozonated organic solvent at room temperature. The company’s technology produces very high ozone solubility in the liquid. The process results in a fast resist removal and it is compatible with all metals tested, including aluminum, copper, gold, tantalum, titanium and tungsten.

In all the Modutek ozone cleaning processes, the exact chemistry is delivered to the point of use in compact equipment that requires fewer steps and a smaller number of tanks than conventional wet benches. In contrast to traditional solvent processes, the ozone process solution has a longer useful lifespan and results in a more benign discharge. Available ozone processes include resist removal, surface preparation and final clean.

Advantages Compared to the Piranha Process

A commonly used conventional acid process is the sulfuric acid and hydrogen peroxide based Piranha process. Key advantages of the ozone cleaning process over the Piranha process include:

  • More rapid processing: Batches of 100 wafers and a rate of 6 batches per hour per process tank allow silicon manufacturing facilities to achieve a higher throughput.
  • Better compatibility: The Piranha process is not compatible with most metals while the Modutek ozone cleaning process has broad compatibility.
  • Fewer particles: The number of particles left on wafers processed with the Modutek ozone cleaning systems is extremely low while Piranha leaves particles on the surfaces.
  • Better safety: The Piranha process operates with highly corrosive chemicals heated to 130 degrees C. The Modutek ozone cleaning systems work at room temperature without harsh chemicals.
  • Lower equipment cost: With fewer tanks and process steps, the Modutek ozone cleaning systems can cost substantially less than a Piranha installation
  • Lower operating costs: Piranha process chemicals are up to twice as expensive as Modutek ozone cleaning chemicals. The total cost of ownership of a Piranha installation is much more than that of an ozone station.

Modutek can evaluate the needs of a silicon manufacturing facility and offer appropriate solutions. The new ozone technology increases manufacturing yields by reducing contaminants and can reduce overall costs. If you want a free consultation or quote on using Modutek’s ozone cleaning process to improve your manufacturing yields, call 866-803-1533 or email [email protected].

Silicon Wafer Cleaning Solutions for Wet Processing Applications

Silicon Wafer Cleaning Solutions for Wet Processing ApplicationsModutek designs and delivers standard and customized silicon wafer cleaning equipment for semiconductor manufacturing facilities and research labs. Supported cleaning processes include RCA clean, Standard Clean 1 and 2, Piranha etch clean, and pre-diffusion clean. The company has specialized in silicon wafer cleaning equipment for over 30 years and emphasizes effective and efficient contaminant and particle removal to ensure high yields, improved throughput and high quality output.

RCA Clean

The RCA clean process is based on a cleaning method developed at RCA Corporation to remove organic residue from silicon wafers. The cleaning solution is made up of 5 parts water, 1 part 27% ammonium hydroxide and 1 part 30% hydrogen peroxide. It removes organic contaminants and leaves a thin layer of oxidized silicon on the surface of the wafer.

Standard Clean 1 and 2

The RCA cleaning process is often carried out in two steps called SC1 and SC2. The SC1 step uses the APM (ammonia/peroxide mixture) solution of the RCA cleaning method to remove organic matter and particles. The SC2 cleaning method uses a solution of hydrochloric acid and hydrogen peroxide or HPM (hydrochloric/peroxide mixture) to remove metallic ions. The two steps prepare the silicon wafer for further processing.

Piranha Etch Clean

The Piranha etch clean removes large amounts of organic material. It is used when there are visible organic contaminants such as photoresist or other hard to remove organic materials. It uses the Piranha solution, made up of a mixture of hydrogen peroxide and sulphuric acid, to clean silicon wafers and hydroxylate surfaces making them hydrophilic. Typical mixture ratios are 3 parts of sulphuric acid and 1 part of 30 percent hydrogen peroxide or higher sulphuric acid ratios of up to 7 to 1. The mixture is highly corrosive and has to be handled with special care.

Pre-Diffusion Clean

The pre-diffusion clean is the final step before the silicon wafer goes into the diffusion furnace. The wafer surfaces must be free from particles and from metallic and organic contaminants. Native oxides or chemical oxide films may have to be removed.

Depending on the nature of the contaminant, a variety of aggressive chemicals, including those from the above cleaning methods, may be used to achieve clean surfaces. Pre-diffusion cleaning is critical because particles or contaminants on the wafer surface may affect the diffusion process and result in defective or low-quality semiconductor output.

Modutek’s Silicon Wafer Cleaning Equipment

Modutek’s dual tank rotary wafer etching system provides a convenient silicon wafer cleaning solution in a compact design. Once the operator loads the wafers and closes the fume door, the wafers are moved to a chemical process tank. After a pre-programmed agitation cycle, the wafers are transferred to the quenching tank where they undergo a set series of rinse cycles. When the set number of cycles is reached, an alarm sounds and the operator can remove the wafers.

Cleaning stations can be manually operated, semi-automatic or fully automated. Modutek’s SolidWorks Simulation Professional and Flow Simulation software allows customers to optimize their operation, reliably reproduce cleaning procedures and precisely control cleaning.

Modutek can evaluate the cleaning requirements of semiconductor manufacturing facilities and research labs and provide custom solutions for their specific requirements. The company’s equipment combines the latest technology with the highest quality and reliability. Modutek can provide their expertise and experience and work directly with clients to improve the silicon wafer cleaning processes for their specific application. For a free quote or consultation on call 866-803-1533 or email [email protected].