# How to Use Air-Gaps to Insulate High-Voltage Semiconductor Chips

> A design for semiconductor chips that uses empty air-filled trenches to provide better electrical insulation for high-voltage transistors without needing complex filling materials.

- **Patent:** US RE48450
- **Original title:** USRE48450E1 - Semiconductor device and method for manufacturing the same
- **Owner:** Renesas Electronics Corp
- **Granted:** 2021
- **Status:** Active
- **Times cited:** 0
- **Field:** semiconductors, automotive, mechanical

## What it does

This patent describes a way to isolate high-voltage transistors on a chip by surrounding them with a trench containing an air-gap. Instead of filling the entire trench with a solid insulating material, which can be difficult and expensive to do perfectly, the process uses an insulating film to cover the device and the trench in a way that leaves an empty space inside. This air-gap acts as a highly effective electrical barrier. The design ensures that the side of the trench at the bottom of the air-gap touches the semiconductor substrate directly, creating a robust isolation structure that prevents electrical leakage between components.

## What it does NOT cover

- Does not cover semiconductor devices that use solid dielectric materials to completely fill the isolation trenches.
- Does not cover designs where the air-gap does not extend through the specific semiconductor layers defined in the manufacturing process.
- Does not cover transistors that are not surrounded by a trench in a plan view.

## The clever bit

The innovation lies in using the deposition process of the insulating film to intentionally create an air-gap that is trapped within the trench, turning a potential manufacturing defect into a functional, high-performance insulation feature.

## Real-world examples

1. Power management integrated circuits (PMICs)
2. High-voltage lateral MOS transistors in automotive control units

## Why it matters

In power electronics, managing high voltages on a tiny chip is a major challenge. If transistors are not properly isolated, they can interfere with each other or break down. This patent offers a simpler, more cost-effective way to achieve high-voltage isolation by leveraging the natural insulating properties of air, which helps manufacturers produce more reliable power-management chips for automotive and industrial applications.

## Frequently asked questions

### What does How to Use Air-Gaps to Insulate High-Voltage Semiconductor Chips cover?

A design for semiconductor chips that uses empty air-filled trenches to provide better electrical insulation for high-voltage transistors without needing complex filling materials.

### Who owns patent US RE48450?

Renesas Electronics Corp owns this patent, granted in 2021.

### When does this patent expire?

This patent is expected to expire on February 23, 2041, when the invention enters the public domain.

### What problem does this patent solve?

In power electronics, managing high voltages on a tiny chip is a major challenge. If transistors are not properly isolated, they can interfere with each other or break down. This patent offers a simpler, more cost-effective way to achieve high-voltage isolation by leveraging the natural insulating properties of air, which helps manufacturers produce more reliable power-management chips for automotive and industrial applications.

### What does this patent NOT cover?

Does not cover semiconductor devices that use solid dielectric materials to completely fill the isolation trenches.

**Full plain-English explainer:** https://patentbrief.org/patent/us/RE48450/android-operating-system

**Original patent:** https://patents.google.com/patent/USRE48450

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._