System for final cleaning of photomasks and photoplates

PROJECT NAME

System for final cleaning of photomasks and photoplates 

PROJECT EXECUTION TIME

Project start: 11. 2017, Project completion date: 06.2018 

CUSTOMER

OJSC “KBTEM-OMO”

PROJECT GOALS

The platform for cleaning of large substrates is designed for final cleaning of photomasks/photoplates, phase shifting and binary photoplates, reticles of optical devices. The machine is designed to address typical tasks of cleaning photomasks/photoplates or reticles used in lithographic instruments (with exposure) with a wavelength of 248 nm and 193 nm. The platform provides soft removal of defects above 0.3 microns, leaving a minimum amount of residual ions SO42 to meet the needs of the semiconductor industry in the production of semiconductor wafers and photomasks/photoplates with technological norm from 250 nm to 90 nm and the ability to expand up to 65 nm.

TECHNICAL DESCRIPTION

The system for cleaning of large semiconductor wafers is targeted at the development of the most advanced technology up to date, defect-free megasonic cleaning of processed (with technological pattern) and unprocessed damage sensitive substrates. In order to achieve maximum optimization of damage-free substrate cleaning, the megasonic energy density should be below the damage threshold at any point of the sample. The applied technology provides a uniform distribution of acoustic energy over the entire surface of the substrate, ensuring perfect cleaning, maximizing the distributed energy that is below the damage threshold of the sample being cleaned. 1 MHz or 3 MHz power sources of megasonic nozzles are selected depending on the type of substrate to be cleaned and particles to be removed.

Another important feature of the system is controlled chemicals dispensing and a special variable speed PVA brush. The machine has a special point chemistry distribution system designed to minimize the consumption of chemicals. The system is equipped with independent nozzles and suction valves that are necessary to eliminate the formation of chemical droplets. The vertical PVA brush system is a mechanical tool for removing stains and protecting against any residues on unprocessed substrates (clean without technological pattern). Deionized (DI) water and chemicals are dispensing (delivered through the system to the desired location) using a PVA brush during the cleaning and self-cleaning processes, as a result of which the brush remains wetted (wet) in deionized water between the cycles and cleaning processes. This allows to increase its service life and start the next cleaning cycle with ideal conditions.

There are many options for expanding and improving cleaning capabilities in addition to these basic functions. Ionization with CO2 provides a reduction of the deionized water resistivity used by the cleaning system, which prevents damage to the ultrasensitive elements. Deionized water (DI) allows to remove organic substances without the use of harsh chemicals. If necessary, such chemicals mixtures and substances like Piranha or SPM can be injected using a special mixing nozzle, which mix individual chemicals at the point of their direct use (specialized point system of chemistry dispensing) with additional heating provided by powerful IR lamps. The machine is capable of drying using infrared lamps without removing the sample from the machine, dispensing N2 and optional IPA. The special “Ultimate Dry-In-Dry-Out” single-stage post-processing system is available with minimal investment and low system maintenance costs. Typical time of the complete cleaning process can vary in the range of 3-5 minutes per substrate/photoplate/wafer, depending on the sample size and additional cleaning parameters.

The combination of these technologies makes the platform ideal for cleaning photoplates used in projection lithography for technological processes in the range from 250 nm to 90 nm and can be expanded up to 65 nm units. This can be achieved by ensuring the purity of the used chemicals, operating conditions and the choice of options such as robotic loading and removal of the processed samples from the SMIF block of the system. The machine is capable to perform backside cleaning of photoplates with pellicles using specialized gripping chuck, reducing the need for unnecessary removal cycles (increasing the service life of the film) and repelliclization. The system can be used to remove adhesive from the frame fixture to prepare its surface for the repelliclization process. In addition, cleaning of the entire front (alignment marks) and rear side of the photoplate with pellicles is available as an option, which reduces the number of pelliclizations required during the entire service life.

APPLICATIONS
  • Silicon (Si) and sapphire semiconductor wafers;
  • CMP semiconductor wafers;
  • Chips on the frame;
  • Displays;
  • ITO coated displays;
  • Photoplates/masks with and without technological pattern;
  • Phase-shifting photoplates/masks;
  • Intermediate photoplates/masks, contact masks;
  • Backside cleaning of pelliclized photoplates;
  • Pellicle frame adhesive removal.
FEATURES
  • Processing of circular-shaped (OD) semiconductor wafers / substrates up to 21″, square wafers/photoplates 15″x15″;
  • Compatible with semiconductor wafers up to 450 mm;
  • Manual loading of photoplates;
  • Photoresist removal and preliminary cleaning;
  • Pellicle adhesive removal;
  • Backside cleaning of pelliclized photoplates;
  • Spray cleaning;
  • 1 MHz and 3 MHz megasonic cleaning;
  • Operation with different types of chemical reagents, including acids, ammonia hydrate, hydrogen peroxide;
  • Ionization of water and chemicals with CO2;
  • Heated deionized water and chemical reagents;
  • Operation in a clean room according to ISO 14644-1-2003;
  • System for final photomask cleaning with a hood with HEPA/ULPA filters;
  • Fixture for final cleaning of binary and phase-shifting photomasks with dimensions (127 x 127 x 2.4) mm, (127 x 127 x 6.35) mm, (153 x 153 x 2.4) mm, (153 x 153 x 6.35) mm;
  • Tank for chemicals;
  • Chemical waste tank.
SPECIFICATIONS
Maximum size of semiconductor wafers/substrates: 21” OD
Maximum size of masks/photoplates: 15 ”x 15”
Typical cleaning time: 3-5 minutes
Megasonic frequency: 1 and 3 MHz
Maximum RF power source output: 40 W
Minimum flow of deionized water (DI): 1.5 l/min
Maximum spinner rotation rate: 4000 revolutions per minute (RPM) (typical limited value 2000 revolutions / minute (RPM))
Control system: PC with LabVIEW interface and touchscreen

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