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Silicon Wafer Services, Reclaim, Deposition, and More from Desert Silicon, LLC.
Wafer Services
Description:
The name Reclaim sometimes strikes
fear into the heart of semiconductor people and it really should not!
Years ago some poor reclaim vendors used to turn out some
pretty bad product that unfortunately gave reclaim wafers a bad name.
Today there are many good reclaim vendors that turn out a very good
product, in many cases as good as the coin roll test described in the last
section. Reclaim wafers are used prime and test wafers
that have been stripped of thin films and re-polished to remove all
patterns and scratches. Todays reclaim vendors will sort your wafers for
thickness and resistivity and in most cases reclaim wafers will preform as
good as normal test wafers. Of course the reclaim wafers will have the
same limitations test wafers do when it comes to Thermal Oxidation and
Photolithography. Remember reclaim wafers like test are not
flat and normally the resistivity spec they are sold under is
very wide, usually 0-100 Ohm/cm. Reclaim wafers can be a little thinner
but most reclaim vendors will pull and dispose of the ones that are to
thin and might cause you problems.
Uses for Reclaim Wafers:
Reclaim wafers can be used for many
of the same things as test wafers. Including Thermal Oxides (with
uniformities of 3-7%), Photolithography .7um-5.0um as
long as you realize the pattern will not resolve all across the wafer.
Thin film deposition and many other uses, Just do not expect the kind of
results you will get from factory sealed Prime, Epi-Prime
or test wafers.
| 1. |
Desert
Silicon provides a wide range of previously used monitor and dummy
wafers.
In cases where there are various films, such as oxide films
or nitride films, these are removed by the appropriate etching
process. In the case of diffusion of layers, grinding is done as
necessary; thus, all types of pre-used wafers are handled.
. Sizes processed 2" 3" 4" 5"
6" 8"
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| 2. |
Exceptional
Quality
The level of finishing following the polishing process is
equal to that of a new or bare dummy or monitor wafer.
. Particle count: Less than 30 @ 0.3µ m
. Recycling frequency: 3 times or more on average.
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Reclaim
Process Flow Chart
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| Receiving |
After
the wafers arrive from the customer, our company records them by
lot number. |
| Incoming
Inspection |
Inspect
all wafers visually, and separate them by type and film type.
Only those wafers that can be reclaimed are selected. |
| Stripping |
Remove
resist, oxide films, nitride films, polysilicon films and metal
films using chemical solutions. |
| Inspection |
After
removing the film(s), once again, only those wafers that
can be reclaimed are selected. |
| Edge
Grinding |
Edge
grinding is performed during reclaim. |
| Lapping |
If
there are diffusion layers, they are lapped off. |
| Cleaning
(caustic) |
Particles and surface damage from
the lapping process are removed in the cleaning process. |
| Mirror
polishing |
Mirror
polishing is performed next. |
| Cleaning |
High
purity chemicals and DI water are used to clean wafer surfaces of
any particles and contaminants. Special processing for removal
of surface metal is performed if necessary. |
| Inspection
of outer appearance |
100%
visual inspection under high-intensity light for haze, chips,
scratches, and other surface defects and damage is performed. |
| Shipping
inspection |
Measurement
inspection for thickness, particles, resistivity, bow, etc.
(Randomized inspection). |
| Packing |
All
packing work is performed inside a Class 10 clean room
environment. |
| Shipping
or Film Deposition |
Films
are deposited as required by the customer. |
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Specifications
for Reclaim
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Standard
Quality (After strip, polish, clean)
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| Wafer
Size |
4"
5"
6"
8" |
Thickness
(minimum) |
400
µ m 485
µ m 485
µ m 610
µ m |
| Front
& Back Surface Inspection |
Chip,
Edge Chip, Crack |
Visual
Inspection |
| Front
Surface Inspection |
Microscratches |
<
7mm length each;
Cumulative length < (diameter/4)mm |
| Pitting |
<
3 |
| Particles |
<
30 @ 0.3 µ m |
| Dirt,
Cloudiness, Pinholes |
Visual
Inspection |
| Back
Surface Inspection |
Dirt,
Scratches, Cloudiness |
contaminants,
spots |
| 100%
Inspection |
Inspect
all wafers under
fluorescent light and focused high intensity light * |
| Randomized
Particle Count Inspection for Shipping |
5
wafers/lot |
| Edge
Exclusion |
3mm |
| With
regard to the processing of product removed during the incoming
inspection, unsuitable product, and damaged product:
1. Product removed during
the inspection are items that cannot be subjected to the reclaim
polishing procedure as of the inspection following removal of
films.
(Substrates that are cracked, chipped, warped, distorted, or of
insufficient thickness for example).
2. Damaged product means
items that were damaged due to human or machine error during processing.
3. Unsuitable products are
items that do not meet the quality standards when checked after
reclaim polishing.
4. Substrates as described
in 1. through 3. above reject wafers are first checked, and then
either destroyed or returned per customer specifications.
* Under fluorescent
light: 500+ lx; High-intensity light: 150000+ lx.
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Facilities
Environment
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| Lapping
Machine |
| Grinding
Machine |
| Edge
Rounding Apparatus |
| Polishing
Machine |
| Wet
Bench |
| Particle
Counter |
| Stress
Counter |
| Thickness
Gauge |
| Flatness
Gauge |
| X-ray
Fluorescence
(for metal contamination determination) |
DEPOSITION
| 1. |
Up
to 300mm
. Silicon Nitride
Poly Silicon
Metals - Sputtered or Evaporated
Other - R&D or Special Requests
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| 2. |
High
Quality Environment and Product results
. Class 10 clean room.
. Typically 1~2% of uniformity within the wafer.
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| 3. |
Consecutive
Procedure - Reclaim to Film Deposition
. Lower cost.
. Reduction of ordering work. (one stop shopping)
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| 4. |
Quick
Response |
| 5. |
Other
Requirements
Please feel free to contact us for other kinds of processing such as patterning and plasma
etching etc.
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Process
Flow Chart
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Process
Proceedure
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Facility
Location
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| Receipt
of wafers |
(Arrival)
condition check |
Incoming
receiving |
| Unpack
carton box |
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Incoming
staging |
| Unpack
plastic packages |
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Class
10 clean room |
| Wafer
appearance check |
Visual
check |
Class
10 clean room |
| Cleaning
before processing |
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Class
10 clean room |
| Deposition
process |
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Class
10 clean room |
| Film
check from appearance |
Visual
check |
Class
10 clean room |
| Measurement
of film thickness |
Film
thickness inspection |
Class
10 clean room |
| Packing |
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Class
10 clean room |
| Pack
in carton box |
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Staging |
| Ship
out |
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Shipping |
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LP/PE-CVD
NITRIDE, Polysilicon Process Specifications
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| Diameter |
2"
3" 4" 5"
6"
8"
12" |
| Standard
Film Thickness *1 |
1000
Å~15000Å |
| Standard
Order Qty./Lot |
100 |
| Minimum
Order Qty./Lot |
25 |
| Uniformity
Within Wafer *2 |
Guarantee
±5% |
| Typical |
1
- 2% |
| Uniformity
Wafer to Wafer *3 |
Guarantee
±5% |
| Typical |
2.0
- 4.0% |
| Film
Thickness Analysis |
Nanospec,
Dectak, Ellipsometry |
*1
Other film thickness can be negotiated.
*2 9-Point measurement.
*3 Average of 9-point
measurement.
. Film thickness will be measured by using our monitor
wafers which are processed with customers' wafers at the same
time for measurement (3pcs/batch).
. The Inspection Report sheet will be attached.
. Wafers will be unpacked in a Class 10 clean room.
Packaging
Shipment will be made with:
1. Using customer's carton box in case we have wafers
supplied by customer;
2. Our packing method (please see below):
* Please inform us for either packaging method, 1 or 2, when
placing an order, if wafers are customer supplied.
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