Backside metallized compound semiconductor device and method for manufacturing the same

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Solution Overview

Problem

Conventional backside metallized compound semiconductor devices using copper face issues with warpage due to excessive thickness, leading to reduced yield in cutting processes and potential thermal and electrical malfunctions.

Innovation Solution

A metal layered structure comprising an adhesion layer, a seed layer, a gold layer, and an electroplated copper layer with controlled thickness (0.2 μm to 5.0 μm) is formed on the backside of a compound semiconductor wafer, with the gold layer blocking copper diffusion and reducing stress, and an anti-oxidation layer is added to prevent oxidation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the backside metallized layer is formed by electroplating copper material, then the heat dissipation effect is improved, but the thickness increases causing warpage and reduced manufacturing yield

Engineering Contradiction:

Improveheat dissipation effectVSAvoidmanufacturing yield

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The backside metallized layer is segmented into multiple functional sub-layers: a first metallized layer (adhesion layer) directly on the substrate, a second metallized layer (barrier layer) on the first layer, and a third metallized layer (copper layer) on the second layer. This segmentation allows each layer to perform its specific function - the adhesion layer provides bonding, the barrier layer prevents diffusion and controls stress, and the copper layer provides heat dissipation - while collectively preventing warpage and maintaining manufacturing yield.

Inventive Principle:

Principle #1Segmentation

2Temperature

If the backside metallized layer is made of gold material, then the heat dissipation effect is improved, but the cost increases

Engineering Contradiction:

Improveheat dissipation effectVSAvoidcost

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

Different materials are used in different layers based on their specific functions: the adhesion layer uses materials optimized for bonding to the semiconductor substrate, the barrier layer uses materials optimized for preventing copper diffusion and controlling stress, and the copper layer uses copper for its superior heat dissipation properties and cost-effectiveness. This local optimization of material properties achieves good heat dissipation while controlling cost.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The backside metallized layer is constructed as a composite structure combining multiple materials (adhesion layer material, barrier layer material, and copper) in a layered configuration. This composite structure leverages the strengths of each material - adhesion, diffusion barrier, and thermal conductivity - while avoiding the high cost of using gold throughout the entire metallized layer.

Inventive Principle:

Principle #40Composite materials

3Temperature

If the copper layer thickness is increased, then the heat dissipation effect is improved, but the stress increases causing warpage

Engineering Contradiction:

Improveheat dissipation effectVSAvoidstress

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

The second metallized layer (barrier layer) acts as an intermediary between the first metallized layer (adhesion layer) and the third metallized layer (copper layer). This intermediate barrier layer serves multiple functions: it prevents copper diffusion into the adhesion layer, controls the stress generated by the copper layer, and maintains the structural integrity of the entire metallized stack, thereby preventing warpage even when the copper layer has sufficient thickness for heat dissipation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

The solution effectively reduces stress and warpage, enhances thermal conductivity, and stabilizes the performance of the semiconductor device by controlling the copper layer thickness and preventing oxidation, thereby improving manufacturing yield and device reliability.

Implementation Method 1

the conventional compound semiconductor device is conferred with a good heat dissipation effect

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

the gold layer blocking copper diffusion

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 3

the backside metallized layer is mostly formed by deposition of the copper material using an electroplating process

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS20240087877A1Backside metallized compound semiconductor device and method for manufacturing the same

Publication Date: 2024.03.14 XIAMEN SANAN INTEGRATED CIRCUIT CO LTD

AI summary

A backside metallized compound semiconductor device includes a compound semiconductor wafer and a metal layered structure. The compound semiconductor wafer includes a substrate having opposite front and back surfaces, and a ground pad structure formed on the front surface. The substrate is formed with a via extending from the back surface to the front surface to expose a side wall of the substrate and a portion of the ground pad structure. The metal layered structure is disposed on the back surface, and covers the side wall and the portion of the ground pad structure. The metal layered structure includes an adhesion layer, a seed layer, a gold layer, and an electroplated copper layer that are formed on the back surface in such order. The method for manufacturing the backside metallized compound semiconductor device is also disclosed.