210-LRS2
Type: Robot machine
for carrier-based final cleaning of silicon wafers.
Product: clean and dry silicon wafers (125 & 156 mm) ready for
inspection, saw damage removal or texturing.
Input: carriers with pre-cleaned silicon wafers.
Removed contamination: traces of slurry, fingerprints.
Process: Ultrasonic cleaning - Ultrasonic cleaning . Spray
Rinsing . Ultrasonic rinsing . Rinsing . Lift-Out.
Cleaning chemistry:
DLC clean 110, NaOH
Periphery: 2 pump filter units, dosage of chemicals, di-water
treatment.
USP’s:
Multifrequency ultrasonics 25/45
kHz for cleaning and rinsing, pH-controlled spray regime, dry
wafers leave the machine without drying by hot air or infrared
system.
200-LRS2
Type: Robot machine
for carrier-based final cleaning of silicon wafers.
Product: clean and dry silicon wafers (125 & 156 mm) ready for
inspection, saw damage removal or texturing.
Input: carriers loaded with pre-cleaned silicon wafers.
Removed contamination: traces of slurry, fingerprints.
Process: Ultrasonic cleaning . Ultrasonic cleaning . Spray
Rinsing . Ultrasonic rinsing . Rinsing . Lift-Out.
Cleaning chemistry:
DLC clean 110, NaOH
Periphery: 2 pump filter units, dosage of chemicals, di-water
treatment.
USP’s:
Multifrequency ultrasonics 25/45
kHz for cleaning and rinsing, pH-controlled spray regime, dry
wafers leave the machine without drying by hot air or infrared
system, can be integrated in back-tracing systems..
Wafer Cleaning
A
sequence of chemistries is typically used to clean silicon
wafers. This chemical sequence does not attack the silicon
material, but selectively
removes the organic and inorganic contamination that resides
on the wafer surface. The following is a typical RCA process;
many variations to the ordering of the sequence and chemical
ratios are used throughout the industry.
General Clean: A
general cleaning is accomplished by using a mixture of
Sulfuric Acid and Hydrogen Peroxide. Mixing these chemicals is
dangerous and generates extreme heat. This industry standard
clean removes organic and inorganic contamination from the
wafer. 2-10 minute clean is recommended. Strong rinse in DI
water is required after this cleaning step.
Particle Removal:
A Megasonic clean (at about 70 C) in a 5:1:1 ratio mixture of
DI water: Ammonium Hydroxide : Hydrogen Peroxide will remove
silica and silicon particles from the wafer, as well as remove
certain organic and metal surface contamination. 2-10 minute
clean is recommended. Strong rinse in DI water is required
after this cleaning step.
Oxide Removal: A
15-60 second dip in 1:20 HF:DI water will remove the native
oxide layer and any contamination in the oxide from the wafer
surface. HF is extremely dangerous and must be handled with
great care. Strong rinse in DI water is required after this
cleaning step.
Metal
Contamination Removal: A Megasonic clean (at about 70 C) in a
6:1:1 ratio mixture of DI water: HCL : Hydrogen Peroxide will
remove certain ionic and metal surface contamination. 2-10
minute clean is recommended. Strong rinse in DI water is
required after this cleaning step.
Spin Rinse Dry:
Wafers should be rinsed and dried in a standard spin-rinse
dryer. Megasonic agitation is commonly used with the chemical bath
and most commonly with the particle removal step. Also, heavy
DI rinse steps are used between each chemical treatment. DI
rinsing may use dump-baths, over-flow baths, and spray-dump
baths, as well as combinations. Proper removal of all cleaning
chemistry with 18MegaOhm DI water is critical and needed after
each chemical bath. Any text book on the topic of
semiconductor or silicon processing is an excellent resource
for further information regarding the RCA cleaning process.
There are
commercially available premixed cleaning solutions that can be
used directly to clean wafers and serve the same purpose of
the RCA cleaning process. These chemicals typically achieve
the function of several cleaning steps with one solution.
![](cleans1.jpg)
Surface Damage Effects in Ultrasonic Cleaning of Silicon Wafers![](icoLeaf.gif)
Resonance Ultrasonic Vibrations for
In-line Crack Detection in Silicon Wafers and Solar Cells![](icoLeaf.gif)
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