Changes to the SPM Process Improves Efficiency and Results

The sulfuric acid hydrogen peroxide mixture (SPM) process effectively strips and cleans wafers but suffers from instability due to the decomposition of the hydrogen peroxide. A heated bath improves performance but increases the rate at which hydrogen peroxide changes into water. Periodically spiking the mixture with extra hydrogen peroxide can restore the required concentration but affects the strip rate. As a result, the SPM mixture has to be changed frequently, leading to high costs for chemicals and frequent downtime on wet bench stations. Working closely with a local semiconductor manufacturer, Modutek has developed a “bleed and feed” process upgrade that addresses these problems and results in substantially longer mixture life and improved process results.

The SPM Process

A typical mixture for the SPM strip and clean process is one part hydrogen peroxide to three parts sulfuric acid. The sulfuric acid parts can go as high as 7 parts but once the process has started, if the concentration changes, the strip rate can change as well. The mixture is heated to 130 to 140 degrees centigrade to increase the strip rate. The higher the temperature, the faster the hydrogen peroxide decomposes to water, diluting the mixture.

To keep hydrogen peroxide in the mixture, more of the chemical is periodically added to the process, spiking the concentration back to its original level. Despite this, the mixture is normally usable for only a few hours at a time and typically has to be replaced several times a day. Replacing the mixture is costly and requires repeated downtime when processing has to wait for a new pour. In addition to the costs of the chemicals, there are treatment and disposal costs that are required to comply with environmental regulations.

Modutek’s “Bleed and Feed” Process Change

Modutek has developed a hydrogen peroxide spiking method that keeps the chemical mixture at a predictable concentration and avoids the requirement for frequent replacement. The method reduces consumption of the chemicals and lets the system run for extended periods without down- time.

Using a two-tank dirty and clean tank process, the “bleed and feed” method involves draining a programmable amount of mixture from the dirty tank prior to each process step. Another programmable amount is fed from the clean tank to the dirty tank. Then programmable amount of sulfuric acid is added to the clean tank and both tanks receive programmable amount of hydrogen peroxide.

When the entire mixture has to be replaced, normally about once every week, the system has a quick drain feature that reduces down time and gets the process up and running again quickly. The whole “bleed and feed” spiking method is PLC controlled and the periodic adding and spiking of chemicals allows the mixture to be used continuously for days at a time.

Benefits of the Modutek Process Change

In addition to savings related to the reduced use of chemicals, the new update improves overall efficiency and achieves better results. Instead of having to shut down the wet bench station every shift to pour new acid, the process can run for days and only requires a complete chemical change once per week. In addition, the process is cleaner and can deliver better cleaning and stripping performance.

Modutek is offering the SPM process upgrade on their new wet bench stations and can provide details regarding chemical use and performance. The company has the experience and expertise to help customers more effectively use the SPM and other processes to ensure they obtain the results they need. Call Modutek at 866-803-1533 for any questions you have with using either the updated SPM process or other wet processes needed for your application.

 

Modutek at 2018 Semicon Conference in China

2018 Semicon Conference ChinaModutek Corporation, a leading provider of wet bench stations and wet process equipment, will be at the Semicon Conference in Shanghai China from March 14-16, 2018 with their factory representative Laserwort Ltd.  They will be located in Hall N2 at booth 2431. Information about the Semicon Conference can be referenced at http://www.semiconchina.org/ and details on Modutek’s attendance at the conference can be referenced at: Modutek at Semicon Conference in China

Come by the Modutek /Laserwort booth to get information and answer any questions you have about using Wet Bench Process Stations for acid/base, solvent and ozone cleaning or photo resist strip.  In addition Modutek will also provide information about the benefits of their new IPA vapor dryer with the HF last process. Modutek serves customers around the world who require any type of wet processing equipment and builds chemical delivery systems for pharmaceutical, biochemical, solar and semiconductor manufacturing.

Additional details on some of Modutek’s products are listed below:

Single Chamber HF Last IPA Vapor Dryer

Benefits include:

  • Most drying cycles completed within 10 to 15 minutes
  • Very low consumption of IPA
  • No moving parts inside drying chamber eliminating wafer breakage
  • Eliminates watermarks
  • Drying technology can be designed into wet bench eliminating one transfer step

Features include:

  • Single drying chamber for DI water rinsing and IPA vapor drying
  • On board HF metering for precision mix ratios
  • Uses an in situ HF etch process with a rinse step before the IPA drying cycle
  • Filter bypass for contamination control with no cassette contact points
  • Easy to change IPA bottles
  • Handles all process sizes (standard wafer carriers to glass substrates)

 

Fully-automated Wet Bench Equipment

Benefits include:

  • In house customization to meet customer process requirements
  • Precise automated process execution and reliable repeatability
  • Full automation control with touch screen
  • Improved yield and reduced errors
  • SolidWorks Simulation software for accurate calculation of process parameters
  • All robotics and software design designed in house
  • Complete design, assembly and test at one location to meet your specifications

 

Semi-automated Wet Bench Equipment:

Benefits Include:

  • Automation control with touch screen
  • Servo motor automation
  • SolidWorks Flow Simulation software
  • SolidWorks Simulation Professional software
  • All robotics and software designed and developed in house
  • Complete design, assembly and test at one location to meet your specifications

 

Manual Wet Bench Equipment:

Benefits Include:

  • High end manual equipment at competitive pricing
  • Meets or exceeds all current safety standards
  • Low cost of ownership
  • Designed to meet any process requirements
  • Can accommodate custom designs and processes
  • Equipment designed for future expansion

 

All wet bench equipment supports the following applications:

  • KOH Etching
  • Quartz cleaning
  • Ozone Strip
  • Ozone Cleaning
  • SC1 & SC2 (RCA Clean)
  • Megasonic Cleaning
  • BOE (Buffered Oxide Etching)
  • MEMs processing
  • All solvent applications
  • Hot phosphoric (Nitride Etching)
  • SPM Cleaning
  • Precision Part Cleaning

Modutek has over 37 years of industry experience and expertise in developing and building wet bench stations and wet process equipment that provides highly reliable results for precision processes. They also provide world-class service, and customer support. Contact Modutek at 866-803-1533 or email Modutek@Modutek.com for a free quote or consultation to discuss your requirements.