Cleaning

Cleaning of substrates is a daily activity in the cleanroom of Device Processing.
Roughly, the cleaning processes can be divided in two principles: wet cleaning and dry cleaning.
In the 10.000 / 100 cleanroom there are two systems which can be used for automatic an semi-automatic wet cleaning of substrates.


Fig. 1
 

   The DMS Yellowtone 197 (Fig. 1) is a vertical single sided substrate cleaner.
This system is placed partly in Cleanroom 10.000 and Cleanroom 100 separated by a wall.
The carrier speed; the process time and the following order of the process steps can be freely chosen.
The wet cleaning steps can be done by a Brush (with or without a surfactant);
High pressure or Megasonic agitation. Drying is performed by an air knife with or without warm air.
A dry cleaning step by UV/ozone is also inline possible.
The DMS can be started from the Cleanroom 100 as from the Cleanroom 10.000.
The status of the cleaning process can be followed on a monitor.

The Branson cleaning system (Fig. 2) is a batch type of equipment which consist of three immersion baths and a hot air drying station.
Glass substrates are placed on a carrier which is moved slowly through the liquid in a vertical way (hip-hop movement) . Bath to bath movement is done manually.
The first bath contains a hot soap solution (60 degrees) and can be agitated ultrasonically.
The second bath is a hot ( 60 degrees) megasonically agitated rinse bath in deionized water to remove the soap residues.
Optimal cleaning is reached in the third and final hot (60 degrees) rinsebath (deionized water).
Drying is the final stage using 80 degrees hot air in order to remove adhering water.
This system is used for its flexibility and the ease by which various glass substrate sizes can be cleaned

  


Fig. 2

Dry cleaning processes which are used in the cleanroom are UV/Ozone to remove organic residues and Oxygen plasma treatment in a plasma (barrel) etcher.
For UV/ozone home made as well as commercial systems like UVOX are available and for Oxygen plasma treatment, two at magnetron frequency operating Tepla barrel etchers.

Beside the above mentioned tools available within the Device Processing, a number of other techniques are applied.
These range from:
  • Scrubbing manually using special designed cloths or spunges.
  • Dust free high pressure nitrogen applied by a pistol with ESD-protection.
  • Rotating rinsing systems.
  • Dipping in acids e.g. to remove metals and metal ions.
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