Reverse Conducting Semiconductor Device with Barrier Metal

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Solution Overview

Problem

The existing reverse conducting semiconductor devices face challenges in maintaining a constant contact area between the barrier metal layer and the high-concentration anode layer, leading to variations in diode characteristics due to manufacturing variations in tungsten plug positioning.

Innovation Solution

The design includes a semiconductor substrate with a high-concentration anode layer wider than the barrier metal contact width, featuring through grooves filled with tungsten plugs and a barrier metal layer that borders the anode and high-concentration anode layers, ensuring a constant contact area and preventing material diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the trench gate interval is reduced to improve diode performance, then the area of the anode layer is reduced and diode performance is improved, but it becomes difficult to connect the anode layer and emitter electrode with aluminum contact electrodes

Engineering Contradiction:

Improvediode performanceVSAvoidconnectability of contact electrodes

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent changes the material parameter of the contact electrode from aluminum to tungsten, which has different physical properties (higher melting point, better adhesion to semiconductor materials). This material substitution enables reliable connection in the reduced trench gate interval structure where aluminum would fail.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If tungsten plugs are used to connect the anode layer and emitter electrode, then connectability is improved, but a barrier metal must be provided to prevent material diffusion into the semiconductor substrate

Engineering Contradiction:

Improveconnectability of contact electrodesVSAvoidstructure complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The barrier metal layer acts as an intermediary between the tungsten plug and the semiconductor substrate. It prevents direct contact and potential diffusion of tungsten atoms into the substrate while still allowing electrical connection, thus solving the material diffusion problem without compromising connectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the p+-anode layer is formed in island form, then the area of contact between barrier metal and high-concentration anode layer changes when tungsten plug position shifts, causing variation in diode characteristics

Engineering Contradiction:

Improvecontact area consistencyVSAvoiddiode characteristic consistency

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The anode layer is designed with a larger width than the barrier metal contact width, creating a margin or cushion zone. This ensures that even if the tungsten plug position shifts during manufacturing, the barrier metal remains in contact with the anode layer, maintaining constant contact area and consistent diode characteristics.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Reliability

If the width of the high-concentration anode layer is made larger than the barrier metal contact width, then contact area consistency is improved, but the area of the anode layer increases

Engineering Contradiction:

Improvediode characteristic consistencyVSAvoidanode layer area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The anode layer has non-uniform width: it is wider in the region where barrier metal contact is needed (to ensure constant contact area) and can be narrower in other regions. This local variation in dimension optimizes both reliability and area utilization.

Inventive Principle:

Principle #3Local quality

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 configuration stabilizes the contact area between the barrier metal and high-concentration anode layers, improving diode recovery characteristics and reducing energy losses by optimizing the trade-off between contact resistance and recovery current, thereby enhancing the overall diode performance.

Implementation Method 1

a barrier metal is provided between the tungsten plugs and the anode layer to prevent a material in the tungsten plug from diffusing into the semiconductor substrate (anode layer)

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

an ohmic contact is established between the p+-anode layer and an emitter electrode

Methodology Applied

Scientific EffectOhmic contact: Conduction (electrical)

Data Source

PatentUS9472548B2Reverse conducting semiconductor device

Publication Date: 2016.10.18 MITSUBISHI ELECTRIC CORP

AI summary

A reverse conducting semiconductor device includes a high-concentration anode layer and a barrier metal layer, the width of the high-concentration anode layer is set larger than the width of contact of the barrier metal layer and the high-concentration anode layer, thereby ensuring that the area of contact between the barrier metal layer and the high-concentration anode layer is constant.