Semiconductor Field Layer With Graded Refractive Index

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Solution Overview

Problem

The existing semiconductor device fabrication processes require additional photomasks for passivation layers, increasing cost and complexity, especially at high temperatures where known field layer materials lose structural integrity.

Innovation Solution

A semiconductor device with a field layer made of materials like silicon oxynitride or phosphosilicate glass that blocks mobile ion diffusion and maintains structural integrity at elevated temperatures, eliminating the need for a separate passivation layer by patterning the field layer to have a graded refractive index and residual film stress for effective ion blocking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a field layer material is used that blocks mobile ion diffusion, then reliability is improved, but manufacturing complexity increases due to requiring additional photomasks

Engineering Contradiction:

Improvemobile ion blockingVSAvoidphotomask quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the field layer and passivation layer into a single integrated structure. The field layer is patterned with a graded refractive index profile that simultaneously provides mobile ion blocking and passivation functions, eliminating the need for separate passivation layer and reducing photomask requirements from 4-6 to 3 masks.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The field layer is designed with spatially varying properties - a graded refractive index that changes from the first face to the second face. This local variation in optical properties enables different regions of the same layer to perform different functions: the first region blocks mobile ions while the second region provides passivation, all within a single layer structure.

Inventive Principle:

Principle #3Local quality

2Reliability

If the field layer maintains structural integrity at elevated temperatures, then reliability is improved, but material selection becomes more restricted

Engineering Contradiction:

Improvestructural integrity at high temperatureVSAvoidmaterial selection range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the optical and physical parameters of the field layer material by creating a graded refractive index structure. This parameter variation allows the material to maintain structural integrity at high temperatures (up to 400°C or higher) while still providing the necessary optical functions for mobile ion blocking and passivation, expanding the range of usable materials.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The field layer is constructed as a composite structure with varying composition across its thickness. By combining materials with different refractive indices and thermal stability characteristics in a graded manner, the layer achieves both high-temperature structural integrity and effective mobile ion blocking properties.

Inventive Principle:

Principle #40Composite materials

3Reliability

If the field layer is patterned with graded refractive index, then mobile ion blocking is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvemobile ion blocking efficiencyVSAvoidrefractive index grading control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The graded refractive index profile is established during the initial field layer deposition process rather than requiring subsequent complex patterning steps. This preliminary formation of the gradient structure simplifies manufacturing by incorporating the precision requirement into a single deposition step where the gradient can be controlled through process parameters.

Inventive Principle:

Principle #10Preliminary action

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 approach reduces the number of photomasks required in the fabrication process, maintaining structural integrity and blocking mobile ions effectively, thereby improving the efficiency and reliability of high-voltage diodes without the need for additional passivation layers.

Implementation Method 1

a field layer patterned on the semiconductor layer, the field layer constituted of a material which blocks the diffusion of mobile ions to the semiconductor layer

Methodology Applied

Scientific EffectDiffusion blocking: Diffusion Barrier

Implementation Method 2

which maintains its structural integrity at the elevated temperatures of semiconductor devices fabrication and assembly

Methodology Applied

Scientific EffectThermal stability: Thermal Insulation

Data Source

PatentUS10566416B2Semiconductor device with improved field layer

Publication Date: 2020.02.18 MICROSEMI CORP

AI summary

A semiconductor device constituted of: a semiconductor layer; and a field layer patterned on said semiconductor layer, said field layer constituted of material having characteristics which block diffusion of mobile ions and maintain structural integrity at activation temperatures of up to 1200 degrees centigrade.