A corporate researcher requested help with the following.
Do you have fused quartz wafers? I am interested
in finding out the availability, cost, and lead time for 100 mm fused
silica at 500 +/- 25 micron thickness, both sides polished.
I am interested in learning the thickness tolerance, surface smoothness,
and if the wafer is flat on one side like a typical Si wafers are.
Specifically, we are interested in finding of if the substrates have 500
+/- 25 micron thick with surface roughness of 60-40 scratch & dig (MIL-0-13830A equivalent).
Reference #95768 for specs and pricing.
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In Semiconductors and substrates Specifically What Does scratch/dig Mean and Why is it Important?
In semiconductor substrates, scratch/dig refers to the surface quality specifications used to quantify and control defects on polished wafer surfaces or optical substrates. Specifically, the term "scratch/dig" indicates two distinct types of defects:
Scratch:
A thin, linear surface defect or mark, typically caused during handling, polishing, or cleaning processes.
Defined by its length, width, and visibility under controlled lighting and inspection conditions.
Dig:
A small pit, divot, or round defect on the surface, often resulting from particle impacts, inclusions, or imperfections during polishing or handling.
Measured by its diameter and depth.
How is Scratch/Dig specified?
Scratch/dig standards are typically expressed as two numbers (e.g., 60/40, 20/10, 10/5):
First number (Scratch):
Represents the maximum permissible scratch visibility or width, typically referenced against standard visibility criteria under controlled illumination. Lower numbers indicate fewer and finer scratches.
Second number (Dig):
Indicates the maximum permissible size of digs or pits (often diameter in microns). Lower numbers correspond to smaller, less frequent, and less severe defects.
For example:
Specification
Interpretation
60/40
Moderate scratch/dig allowed; common for general purposes
Premium quality surfaces; used in precision optical or semiconductor applications requiring extremely low defect densities
Why is Scratch/Dig important?
Scratch/dig specifications directly impact:
Device Yield & Performance:
Surface defects can affect the yield and reliability of semiconductor devices. Scratches or digs might lead to defects like short circuits, open circuits, leakage paths, or uneven film deposition.
Optical Properties:
For optical or MEMS applications, surface defects significantly influence optical clarity, scattering, reflectivity, or transmission.
Quality and Reliability:
Ensuring surfaces meet tight scratch/dig standards reduces risks associated with device failure or inconsistent performance, critical for high-performance electronics, sensors, photonics, and MEMS devices.
Cost & Manufacturing Efficiency:
Stringent scratch/dig standards help manufacturers avoid costly reworks, device rejection, and yield losses, enhancing overall production efficiency and profitability.
Applications based on Scratch/Dig requirements:
Semiconductor Wafers: Lower scratch/dig values are preferred for advanced semiconductor devices, RF, photonics, and high-frequency applications.
Optical Substrates: Precision optics, laser systems, and optical MEMS require extremely low scratch/dig values to prevent optical scattering and degradation.
Sensor/MEMS Substrates: Surface defects impact sensitivity and accuracy; hence tight scratch/dig control is critical.
Common Standards:
Scratch/dig criteria commonly follow industry standards, such as:
MIL-PRF-13830B (Military Performance Standard)
ANSI/OEOSC OP1.002-2009 (American National Standards Institute/Optics and Electro-Optics Standards Council)
In summary, scratch/dig specifications precisely define permissible surface defect levels on semiconductor substrates and wafers, directly influencing yield, reliability, and performance of semiconductor and optical devices.
