Phonon Scattering Control MOS Capacitor 220pF 50V Single Layer Chip For High-Power RF

HACC221S50V300 Phonon Scattering Control MOS Capacitor — 220pF 50V Single Layer RF Chip

Product overview: The HACC221S50V300 is a single-layer metal-oxide-semiconductor (MOS) capacitor with a nominal capacitance of 220pF ±10% and a 50V DC working voltage. It is built on a high-conductivity float-zone silicon substrate with a 300nm thermal silicon dioxide (SiO₂) dielectric and a TiW-Au metallization stack. Its defining characteristic is phonon scattering control — the dielectric, substrate, and metal interfaces are engineered so that heat generated by RF loss is conducted away efficiently instead of building up in a hot spot. This suits high-power RF stages where thermal stability limits performance.

What Is Phonon Scattering Control?

In a solid, heat is carried by phonons, which are quantized lattice vibrations. Any feature that interrupts a phonon's travel — grain boundaries, crystal defects, and rough or chemically mixed interfaces — scatters it and lowers thermal conductivity, so heat stays where it was generated. Phonon scattering control means engineering the dielectric, substrate, and metallization interfaces to keep phonon transport efficient: single-crystal float-zone silicon has a long phonon mean path (the average distance a phonon travels before it is scattered), the dielectric is a dense thermal oxide with minimal defect density, and the thick gold metallization provides a low-resistance thermal path to the mounting surface.

Engineering Notes: How the Thermal Path Is Built

• Substrate: single-crystal float-zone silicon with a continuous lattice and high thermal conductivity, so heat spreads away from the dielectric over a large volume.
• Dielectric: dense thermal SiO₂ grown at high temperature, with low defect and void density and therefore few internal scattering centers.
• Interfaces: thin, fully bonded TiW adhesion layers avoid the rough, partially bonded interface that scatters phonons and impedes heat flow.
• Metallization: thick Au top electrode and full-area Au backside form a wide, low-resistance thermal path from the dielectric to the mounting surface.
• Low ESR: reduces the amount of signal power converted into heat in the first place.

Key Specifications (T = 25°C unless noted)

Typical Applications

• High-power RF amplifier output matching and decoupling
• RF power modules requiring stable parameters under load
• Solid-state RF heating and plasma excitation sources
• High-power filter, combiner, and matching networks
• Industrial RF power supplies