LPCVD Undoped Polysilicon

Polysilicon Wafer Deposition Services

Polysilicon deposition represents one part of our broader MEMS foundry and wafer processing capabilities. Our engineering team works closely with customers to integrate polysilicon layers with complementary thin-film deposition processes and micromachining steps.

Our wafer services support:

• MEMS sensor fabrication
• Semiconductor device development
• Advanced microfabrication technologies
• Custom wafer process integration
• Prototype development through production manufacturing

By combining LPCVD polysilicon deposition with MEMS foundry services like photolithography, wet etch, and DRIE silicon etch, Rogue Valley Microdevices enables innovators to build reliable, high-performance devices on silicon wafers.

LPCVD Polysilicon Deposition Process

LPCVD polysilicon is deposited when silane (SiH4) decomposes into silicon (Si) and hydrogen (2H2) at temperatures 580C° and above. Engineers widely use LPCVD polysilicon deposition to create structural and electrical layers in MEMS devices and semiconductor technologies. During deposition, precursor gases such as silane react at elevated temperatures inside a controlled furnace environment. This reaction forms a uniform polysilicon layer across the silicon wafer surface.

LPCVD polysilicon offers several advantages for MEMS fabrication:

• Excellent film uniformity across silicon wafers
• Strong adhesion to silicon substrates
• Good conformal coverage over microstructures
• Stable mechanical properties for MEMS devices
• High compatibility with semiconductor process flows

These characteristics make LPCVD polysilicon an essential material for precision MEMS device fabrication and advanced wafer processing.

Polysilicon as a Structural Material for MEMS

Polysilicon serves as one of the most widely used structural materials in MEMS devices. Engineers build many microelectromechanical components directly from polysilicon layers.

Use of polysilicon as a structural material supports devices such as:

• Pressure sensors
• Accelerometers
• Resonators
• Electrostatic actuators
• Micro-mechanical beams and diaphragms

Because polysilicon combines semiconductor compatibility with mechanical strength, it enables engineers to integrate sensing, mechanical movement, and electrical functionality within a single device structure.

Polysilicon Sacrificial Layers for MEMS Surface Micromachining

Engineers frequently use undoped polysilicon as a sacrificial layer in MEMS surface micromachining processes. During fabrication, the polysilicon layer supports structural films like silicon nitride, silicon dioxide, or PVD metal layers while device features form above it. After engineers complete the structural layers, they remove the sacrificial polysilicon to release suspended MEMS components.

Many MEMS processes pair polysilicon sacrificial layers with xenon difluoride (XeF₂) vapor etching for the final release step. XeF₂ selectively etches silicon and polysilicon while leaving many structural films largely unaffected. During XeF₂ processing, the sacrificial polysilicon reacts with the etchant and forms volatile byproducts that exit the chamber. This vapor-phase release process eliminates liquid surface tension and helps prevent stiction in delicate MEMS structures.

LPCVD Polysilicon Film Options

Supported Wafer Sizes and Materials

LPCVD Polysilicon for MEMS Fabrication and Semiconductor Devices

Polysilicon plays a central role in MEMS fabrication and semiconductor manufacturing. At Rogue Valley Microdevices, we provide LPCVD polysilicon deposition on silicon wafers that supports MEMS sensors, actuators, and advanced microdevices.

Engineers rely on polysilicon because it combines excellent mechanical strength with useful electrical properties when doped. Similar to LPCVD Nitride, we offer high-quality polysilicon films using Low Pressure Chemical Vapor Deposition (LPCVD), enabling consistent film thickness and strong uniformity across the wafer.

As a flexible MEMS foundry and wafer services provider, Rogue Valley Microdevices supports both prototype development and production wafer processing.

Polysilicon for Surface Micromachining

Many MEMS fabrication technologies rely on surface micromachining polysilicon processes. Engineers use multiple polysilicon layers separated by sacrificial oxide films to build suspended mechanical structures.

Surface micromachining with polysilicon enables the creation of:

• Suspended micro-mechanical beams
• Micro-springs and resonators
• Electrostatic actuators
• Complex MEMS device architectures

This process technology allows engineers to create moving mechanical structures directly on silicon wafers.