Thermal Oxide on Silicon wafers

Silicon Oxide Growth for MEMS and Semiconductor Devices

Thermal oxidation plays a critical role in semiconductor manufacturing and MEMS fabrication. At Rogue Valley Microdevices, we deliver precision thermal oxidation services on silicon wafers, enabling engineers to grow high-quality silicon dioxide (SiO₂) layers for insulation, passivation, and process masking.

During thermal oxidation, oxygen or steam reacts directly with the silicon surface at elevated furnace temperatures. This reaction converts the surface of the silicon wafer into a dense silicon dioxide layer.

Because the oxide grows directly from the silicon substrate, thermal oxide delivers exceptional interface quality, uniform thickness, and long-term reliability. These characteristics make thermal oxide essential for MEMS sensors, microdevices, and advanced semiconductor components.

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

Silicon Wafer Sizes Supported

50.8mm, 76.2mm, 1000mm, 125mm, 150mm, 200mm

Dry Thermal Oxidation

Our Dry oxidation uses oxygen as the oxidizing species and produces dense, high-quality oxide films. This method is typically used when thin, high-precision dielectric layers are required.

Dry Chlorinated Thermal Oxidation with a Forming Gas Anneal

Using dry chlorinated thermal oxide can help to eliminate metal ions, enabling your device to achieve its highest level of performance. In addition a A forming gas anneal (FGA) after oxidation lets you passivate any dangling bonds. This is important because dangling bonds at the silicon interface can affect the insulating properties of your oxide. By adding the FGA, you’ll receive the maximum benefit of your dry chlorinated oxide.

Wet Thermal Oxidation

During wet oxidation, water vapor is introduced to accelerate oxide growth rates. This is the process used to produce the thicker oxide layers required my many MEMS and Optical applications. Wet oxidation can grow oxide significantly faster than dry oxidation while maintaining good film uniformity.

By tailoring oxidation conditions, including temperature, and gas ratios, we can precisely control oxide thickness and film properties for your application.

MEMS Foundry Wafer Processing

Thermal oxidation represents one part of our broader MEMS foundry and wafer processing capabilities. Our engineers work closely with customers to integrate oxide growth with complementary thin-film deposition and micromachining processes.

Our wafer services support:

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

By combining thermal oxidation with a full suite of MEMS fabrication services, Rogue Valley Microdevices helps innovators build reliable microdevices on high-quality silicon wafers.

Silicon Dioxide Layers for MEMS Devices

Engineers rely on thermally grown silicon dioxide to create reliable dielectric layers in MEMS devices and semiconductor technologies. Thermal oxide protects underlying silicon while providing strong electrical insulation during fabrication.

Common uses for thermal oxide on silicon wafers include:

• Electrical insulation layers
• Surface passivation and environmental protection
• Masking layers for silicon etching processes
• Sacrificial layers used to release MEMS structures
• Dielectric layers for sensors and integrated microelectronics

Because thermal oxidation transforms the silicon surface into oxide, the resulting layer forms a strong, stable interface with excellent adhesion and low defect density. These properties support high-reliability MEMS devices and complex microfabrication processes.

Thick Thermal Oxide (>1 µm) for MEMS and Optical Waveguide Fabrication

Many MEMS fabrication processes require thick thermal oxide layers greater than 2 µm to support micromachining, device isolation, and advanced photonic structures. Thick oxide provides strong dielectric insulation and durable masking capability during deep silicon etching, while also serving as a critical optical layer in integrated photonics.

At Rogue Valley Microdevices, we grow thick silicon dioxide layers on silicon wafers using optimized oxidation processes developed for MEMS fabrication and silicon photonics applications. Wet oxidation enables faster oxide growth while maintaining excellent film integrity, low defect density, and strong wafer-level thickness uniformity.

In addition to MEMS applications, thick thermal oxide plays an important role in silicon nitride and doped oxide waveguide platforms. These oxide layers commonly serve as the undercladding layer, providing optical isolation between the silicon substrate and the waveguide core. After deposition and patterning of the waveguide material, additional oxide layers can be deposited or grown to form the overcladding, which protects the optical structure and stabilizes the refractive index environment surrounding the waveguide.

Engineers commonly use thick thermal oxide for:

• Deep silicon etch masking for DRIE and other micromachining processes
• Electrical isolation layers in sensors and integrated microdevices
• Sacrificial layers used to release movable MEMS structures
• Field oxide layers for device isolation
• Undercladding layers for silicon nitride or doped oxide optical waveguides
• Overcladding layers that encapsulate and protect integrated photonic structures
• Protective layers during complex wafer processing steps

Because thermally grown oxide becomes part of the silicon substrate itself, there is no risk of poor film adhesion.In addition, these films have high dielectric strength, and low defect density compared to many deposited dielectric films.

Thermally grown thick thermal oxide layers provide a reliable foundation for complex wafer-level fabrication processes.