Superjunction High Voltage Devices Wafer Bonding

Solution Overview

Problem

Conventional trench-type superjunction device manufacturing processes involve complex steps, leading to higher costs, potential defects, and reduced production yield due to thermal and mechanical stresses.

Innovation Solution

A method of forming superjunction devices using wafer bonding, which involves providing a semiconductor layer with trenches, doping the sidewalls, and bonding a dielectric layer to cover the trenches, followed by substrate removal and dielectric layer etching to form active regions, thereby simplifying the process and reducing stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional trench refill process is used, then trenches are filled with insulative material, but manufacturing cost increases and production yield decreases due to multiple process steps

Engineering Contradiction:

Improvetrench filling qualityVSAvoidproduction yield

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent extracts and removes the substrate after wafer bonding, eliminating the need for trench refill with insulative material. The substrate itself serves as the structural support, and its removal leaves the doped regions exposed and functional without requiring additional filling steps, thereby reducing process complexity and improving yield.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the manufacturing process into distinct phases: forming doped regions through sidewall doping, bonding the wafer to a substrate for structural support during processing, and then removing the substrate. This segmentation allows each step to be optimized independently, eliminating the need for trench refill while maintaining process control.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If conventional trench refill process is used, then trenches are filled with insulative material, but manufacturing cost increases due to additional process steps

Engineering Contradiction:

Improvetrench filling qualityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent extracts and removes the substrate after wafer bonding, eliminating the need for trench refill with insulative material. The substrate itself serves as the structural support, and its removal leaves the doped regions exposed and functional without requiring additional filling steps, thereby reducing process complexity and improving yield.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs sidewall doping before substrate removal, preliminarily forming the doped regions that will become the functional elements after substrate removal. This preliminary action ensures that the doped regions are properly formed and positioned before the final structural changes occur, eliminating the need for subsequent trench refill operations.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If conventional trench refill process is used, then multiple process steps are performed, but thermal and mechanical stresses are introduced affecting production yield

Engineering Contradiction:

Improvetrench filling qualityVSAvoidproduction yield

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent extracts and removes the substrate after wafer bonding, eliminating the need for trench refill with insulative material. The substrate itself serves as the structural support, and its removal leaves the doped regions exposed and functional without requiring additional filling steps, thereby reducing process complexity and improving yield.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the fundamental parameter of structural support from requiring filled trenches to using the substrate itself during processing. By modifying how structural support is provided (through wafer bonding rather than trench refill), the process avoids the thermal and mechanical stresses associated with multiple high-temperature processing steps and material deposition.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method reduces manufacturing costs, minimizes defects, and increases production yield by simplifying the process and reducing thermal and mechanical stresses, while enhancing avalanche breakdown voltage characteristics.

Implementation Method 1

bonding a dielectric layer to a semiconductor layer

Methodology Applied

Scientific EffectWafer bonding: Welding

Data Source

PatentUS9461109B1Method of forming superjunction high voltage devices using wafer bonding

Publication Date: 2016.10.04 ICEMOS TECH

AI summary

A method of forming a superjunction device includes providing a semiconductor layer having first and second opposing main surfaces and a first doping concentration of a dopant of a first conductivity type, forming at least one device proximate the first main surface, forming at least one trench adjacent to the device and extending into the semiconductor layer from the first main surface, doping at least a portion of a sidewall of the trench with a dopant of a second, different conductivity type to form a first region in the semiconductor layer adjacent to the sidewall and extending at least partially between the first and second main surfaces, providing a substrate with a first dielectric layer arranged thereon, bonding the first dielectric layer to the first main surface to cover the trench and at least a portion of the device, and removing the substrate.