Semiconductor wafer specifications cover diameter, thickness, crystal orientation, doping type and resistivity, edge geometry (flats or notch), surface finish, and tolerances on flatness, bow, and warp. Most silicon wafer dimensions follow SEMI (Semiconductor Equipment and Materials International) standards, which keep wafers interchangeable across fab tooling worldwide. Compound and wide-bandgap materials like silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs), and indium phosphide (InP) follow similar conventions with material-specific thickness and defect specs. This guide covers the spec fields to define and verify before you place an order.
Wafer thickness scales with diameter because larger wafers need more mechanical rigidity to resist bow, warp, and breakage during handling. The values below are typical nominal thicknesses in current industry use; exact figures vary by supplier, wafer generation, and application, so always confirm against the specific lot's data sheet or COA.
| Diameter | Typical Thickness | SEMI Standard Reference |
|---|---|---|
| 2" (50.8 mm) | ~275–325 µm | SEMI M1 (flats-based) |
| 3" (76.2 mm) | ~375–425 µm | SEMI M1 (flats-based) |
| 100 mm (4") | ~525 µm ± 25 µm | SEMI M1 |
| 125 mm (5") | ~625 µm ± 25 µm | SEMI M1 |
| 150 mm (6") | ~675 µm ± 25 µm | SEMI M1 |
| 200 mm (8") | ~725 µm ± 20 µm | SEMI M1 (notch-based) |
| 300 mm (12") | ~775 µm ± 20 µm | SEMI M1 (notch-based) |
Non-standard thicknesses (thinned, ultra-thin, or thick "power" wafers) are available on custom order but fall outside the ranges above — specify the exact thickness and tolerance you need in the RFQ.
Orientation describes which crystal plane is parallel to the wafer surface, and it changes how the wafer cleaves, etches, and performs electrically:
Orientation and dopant type are physically marked on the wafer edge so fab equipment and operators can identify them without additional testing:
Doping sets whether a wafer is n-type or p-type and, together with doping concentration, sets its resistivity:
Resistivity and doping concentration move inversely — more dopant atoms mean more free carriers and lower resistivity. Typical bands used across the industry:
| Doping Level | Typical Resistivity Range | Common Use |
|---|---|---|
| Lightly doped / high resistivity | Roughly 10–10,000+ Ω·cm | RF, radiation detectors, high-voltage devices (often FZ material) |
| Standard / medium doped | Roughly 1–10 Ω·cm | General CMOS and IC substrates |
| Heavily doped / low resistivity | Roughly 0.001–0.02 Ω·cm | Degenerate (n++/p++) substrates for power devices and low-resistance contacts |
These bands are a general guide — exact resistivity depends on the specific ingot and should always be confirmed against a four-point-probe measurement and the lot's Certificate of Analysis.
SiC substrates are specified by polytype, not just orientation, because different polytypes have meaningfully different electrical properties:
| Property | 4H-SiC | 6H-SiC |
|---|---|---|
| Bandgap | ~3.23 eV | ~3.0 eV |
| Electron mobility | ~900 cm²/V·s | ~400 cm²/V·s |
| Typical use | Power electronics: MOSFETs, Schottky diodes, high-voltage/high-frequency devices | LEDs, UV photodetectors, and specialty applications favouring its directional (anisotropic) properties |
| Commercial availability | Dominant polytype in the power device market | Niche/specialty availability |
4H-SiC's higher electron mobility supports faster switching and lower on-resistance, which is why it dominates commercial power electronics, while 6H-SiC is reserved for applications where its specific optical or mechanical properties are the deciding factor.
Micropipe density (MPD): a micropipe is a hollow-core screw dislocation running along the crystal growth direction; it creates a leakage path and can compromise device yield. Research-grade SiC is often specified around MPD < 15 cm⁻², while modern production-grade substrates are typically specified as micropipe-free or MPD near 0–1 cm⁻² — a dramatic improvement over early-generation SiC material. SiC wafers are typically available from 2" up to 6" diameter, thinner than comparable silicon wafers at a given diameter; confirm exact thickness and MPD spec against the lot's data sheet.
Include the following fields in any wafer RFQ to get an accurate, fast quote:
Mihron Metalyx sources silicon (CZ/FZ, 2"–12"), 4H/6H SiC (2"–6"), GaN-on-SiC and GaN-on-sapphire epiwafers, and GaAs/InP/GaSb/InAs/InSb substrates from a bonded Toronto warehouse, with wafer reclaim, dicing, and metrology services available and a Certificate of Analysis on every lot. Send us the spec fields above and we'll quote within 48 hours — no minimum order on standard silicon.
A 200mm (8-inch) silicon wafer typically has a nominal thickness of about 725 microns, with a tolerance of roughly plus or minus 20 microns, following SEMI M1 conventions. Exact thickness can vary by supplier and application, so confirm against the specific lot's data sheet.
Wafers under 200mm typically use a primary flat to indicate crystal orientation and a secondary flat, at a specific angle and length relative to the primary flat, to indicate dopant type. Wafers 200mm and larger use a single alignment notch for orientation, with dopant type specified in the accompanying documentation rather than the edge shape.
4H-SiC has a wider bandgap (about 3.23 eV vs. about 3.0 eV) and more than double the electron mobility of 6H-SiC (about 900 cm²/V·s vs. about 400 cm²/V·s), which gives it faster switching and lower on-resistance. That makes 4H-SiC the dominant polytype for power electronics, while 6H-SiC is used mainly for LEDs, UV photodetectors, and specialty applications.
A micropipe is a hollow-core screw dislocation running through a SiC crystal along its growth direction; it creates a leakage path that can compromise device performance and yield. Research-grade SiC substrates are often specified around 15 micropipes per square centimetre or fewer, while modern production-grade material is typically specified as micropipe-free or near 0-1 per square centimetre.
A complete wafer RFQ should specify material, diameter, thickness and tolerance, crystal orientation, dopant type and resistivity range, grade (prime/test/dummy/reclaim), surface finish, flatness/bow/warp tolerance if non-standard, edge type (flat convention or notch), quantity, required lead time, and any documentation needed such as a Certificate of Analysis.
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