Buy Undoped / Intrinsic Silicon Wafers for Sensors
UniversityWafer stocks and sources undoped (intrinsic) silicon wafers for sensor fabrication in U.S. labs, supporting single-wafer prototyping through structured 100 mm and larger runs. Choose high-resistivity substrates to reduce leakage current and keep sensor noise low.
For fast procurement, order stocked intrinsic silicon online or request a quote for custom resistivity, finish, or oxide thickness.
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Popular Sensor-Wafer Options
- Intrinsic resistivity: >7,000–10,000 Ω·cm (low-noise designs)
- Ultra-high resistivity: >20,000 Ω·cm (advanced 100 mm platforms)
- Finishes: SSP or DSP (for bonding / double-sided processing)
- Optional ~1 µm thermal oxide (isolation / optical interface)
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Practical Spec Guide for Intrinsic Sensor Wafers
Undoped silicon selection is mainly driven by your noise budget, tooling, and sensor stack. Thinking through these parameters early can prevent costly re-orders once fabrication begins.
- Resistivity: Many U.S. sensor programs use >7,000–10,000 Ω·cm for low-noise designs, with some 100 mm platforms using >20,000 Ω·cm.
- Diameter: 1–4 inch for prototyping; 100 mm for pilot runs and higher die counts.
- Finish: SSP for front-side processing; DSP for bonding, backside steps, or double-sided patterning.
- Orientation: <100> or <111> depending on etch behavior and mechanical properties.
- Oxide: Optional ~1 µm thermal oxide can accelerate early process steps and improve isolation.
Why Undoped Silicon Reduces Noise in Sensors
Intrinsic silicon minimizes free carriers in the substrate, which helps suppress parasitic conduction paths and dielectric losses. For precision sensors, that means improved isolation, lower leakage, and more stable operation across temperature ranges—including cryogenic and aerospace-relevant environments.
Undoped substrates also give designers more control over depletion regions and junction profiles, helping meet stringent leakage targets used in radiation and high-impedance sensing work.
Typical Undoped Wafer Sizes Used in U.S. Sensor Fabrication
Many U.S. sensor teams scale in stages. Small wafers are used to validate etches, oxides, and first layouts; 100 mm wafers are used when the design stabilizes and teams need repeatable runs.
| Diameter | Common Sensor Use |
| 1" (25.4 mm) | Single-die prototypes, device physics studies |
| 2" (50.8 mm) | MEMS test structures, early Hall and piezoresistive designs |
| 3" (76.2 mm) | Optical arrays and larger R&D die sets |
| 4" (100 mm) | Pilot sensor layouts, radiation and low-noise platforms |
Where Intrinsic Silicon Shows Up in Sensor Types
- MEMS / Pressure Sensors: intrinsic wafers can act as stable mechanical support layers for diaphragms and etched structures.
- Hall Effect Sensors: undoped substrates help keep bulk carrier effects from disturbing thin active regions.
- Piezoresistive Sensors: simplifies substrate electrical behavior while stress is transferred into doped resistor regions.
- Optical & Radiation Sensors: supports high-impedance designs where leakage and noise must be minimized.
U.S. Supply Chain and Lead-Time Planning
For U.S. sensor programs, tariffs and customs delays can become real project risks—especially for grant-funded, defense, or medical timelines. Using a supplier with U.S.-focused stock helps reduce scheduling uncertainty and keeps prototyping cycles short.
A common strategy is to begin with small quantities (even single wafers), iterate quickly, then scale once the sensor design is stable.
Integrating Undoped Silicon with Other Sensor Materials
Many sensor stacks combine silicon with additional materials such as glass, sapphire, or III-V substrates. Undoped silicon often serves as a handle wafer, cap, or mechanically robust base that simplifies bonding, dicing, and packaging.
For example, IR or Hall sensor programs sometimes combine InAs device regions with silicon support structures to balance performance and manufacturability.