Quartz part cleaning
In a vertical semiconductor furnace as well as in a horizontal tube furnace, many quartz parts and sometimes SiC parts are
used, like process tube, liner, pedestal, boat, T/C-tube, injector
and other smaller parts.
The furnaces are used for different standard processes like
diffusion,
doping,
oxidation, low pressure chemical
vapor deposition LPCVD
(nitride,
poly-silicon,
TEOS), or also for special low temperature applications like
polyimide baking, copper anneal, low-k anneal, SOG or hydrogen anneal.
In order to achieve good process results over long time, it is
necessary to keep the process chamber very clean. Cleaning of
quartzware
has to be done by wet cleaning usually. Only in a few cases, special
in-situ cleaning methods are available, e.g. burn out cleaning for the
polyimide cure process.
Most critical for the quartz ware are the LPCVD processes, because
during the deposition process the quartzware in the process chamber
will be coated. The coating creates particles by flaking and changes
the chamber properties. Therefore proper cleaning is necessary.
Cleaning Chemistry
For removing the poly-silicon, nitride or oxide layer, acids
mixtures, mainly consisting of hydrofluoric acid HF and nitric acid
HNO3 are used:
Silicon oxide can be etched either by pure HF or by buffered HF:
SiO2 + 6HF 
H2SiF6 + 2H2O
SiO2 + 4HF + 2NH4F (NH4)2SiF6 + 2H2O
Poly-silicon is etched based on hydrofluoric
acid and nitric acid. HNO3 oxidizes silicon, HF etches the
oxidized compound. NH4F may be used.
18HF + 4HNO3 + 3Si 3H2SiF6 + 4NO + 8H2O
For Nitride also a mixture of HF and HNO3
is
used. Sometimes acetic acid CH3COOH is added.
Spray Cleaning Equipment
With increasing size of silicon wafers and the furnaces, the quartz parts used in the furnace
become also larger, mainly the quartz tube, the liner and the quartz boat. Quartz tube cleaner and
quartz boat cleaner design had to be adapted. In order to save chemicals and make cleaning operation
very effective, spray cleaning is used in Polyflow cleaning equipment. A combination of
actuating and fixed nozzles insures proper cleaning and easy loading of the equipment.
Immersion cleaning is used in some tools only for small parts. Drying of the parts
is also performed in the equipment. Several different types of cleaning equipment are available.
Here we describe only the most common tools. Further models are available on request.
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Typhoon quartz cleaner
The most advanced tool is the Typhoon
system, developped for all quartz
parts of large furnaces for silicon wafers up to 300mm. Maximum
productivity is assured with quad tanks and simultaneous/ independent
operation of the process chambers. Each chamber provides a recirculated
strong cleaning solution followed by a single pass polish solution and
four powerful rinses. With the Typhoon you'll clean incompatible quartz
free from the fear of cross contamination.
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OmniClean quartz cleaner
The OmniClean is Poly-Flow's most
universal quartzware cleaner. This
versatile system allows you to handle a complete set of quartzware from
either a vertical or a horizontal furnace. The right chamber is
engineered for all types of tubes: flanged, plain end or closed end,
single wall or double, all can be fixtured. The patented Turbo-Nozzle
is vertically actuated making loading simple, while the drain cone
includes a full set of upblast nozzles. The left chamber features the
exclusive birdcage carousel for pedestals, cantilevers, sheaths and of
course, quartz boats of all types and sizes.
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Double-Double quartz cleaner
Poly-Flow's classic vertical tube tower, the Double/Double, is the
lowest priced, fully automatic quartzware cleaner available. It can be used for quartz parts from
4" and 6" furnaces. Yet this workhorse doesn't skimp on safety, durability or features. The dual
chamber system precision cleans quartzware behind a single, interlocked front door. Each Double/Double
has separate tube and parts chambers. They can also be customized with twin tube fixturing or specialized
cabinets to fit your fab exactly.
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Epitaxial quartz cleaner
For the cleaning of the quartz parts of
an epitaxy system, Polyflow developed a special cleaning equipment.
Bell jars up to 900mm in diameter and 1200mm in height can be handled in
this machine. Spray cleaning is used for the bell jar and the
thermocouple sheat while door and small parts are cleaned by an
immersion process.
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Process control
A state of the art touch screen
controller makes operation of the tool easy. Process choices are
unrestricted for you can specify as many as three storage tanks for
recirculating acids. In any recipe you can program the appropriate acid
mixture to remove stubborn contamination and then follow it with a
quick polish etch. You'll appreciate the paperless operation and
maintenance manuals. All the documentation is available on the
touchscreen whenever it is needed. Plus, your operation is continuously
monitored and logged by our latest generation of PCMS software.
All quartzware is loaded on precision fixturing. Operator instructs tool to
automatically blend chemicals in the internal holding tanks from the bulk chemical
delivery system. Tubes or liners are sprayed with concentrated acid inside and/or outside.
Parts fixtured on the carousel are spray-etched and rinsed. Injector lines are connected
as needed to clean internal passages. Single-use acid is sprayed on all
parts for a final etch from dedicated piping and nozzles.
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- Visual Logic Controller
- Intuitive Graphical User Interface
- Icons/graphics on screen
- Pentium IV
- Windows Operating System
- Process and safety functions
- Paperless Manuals
- Function charts
- Error log
- Inputs/outputs
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Materials
All main parts of the
equipment are made from polypropylen and PVC parts. Fire safe material
CPVC and PVDF can be used.
* We represent Polyflow together with MDC Switzerland. We are
responsible for Germany, Austria and northern Europe.
| Crystec Technology Trading GmbH est à votre disposition pour vous aider dans la réalisation de vos projets. |
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