Alpha Particle Blocking Shields in Semiconductor Wiring

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Soft error rates in integrated circuits are increased due to ionizing radiation from alpha particles emitted by solder bumps containing radioactive isotopes, which can penetrate and disrupt sensitive semiconductor materials, especially as circuit scaling and voltage decrease.

Innovation Solution

Incorporating alpha particle blocking shields in the wiring levels of integrated circuits, positioned between sensitive device areas and solder bumps, to prevent a predetermined percentage of alpha particles from reaching the devices by calculating the necessary material and distance to effectively block the radiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If circuit scaling and voltage decrease to increase circuit density, then productivity increases, but soft error rate increases due to higher sensitivity to alpha particles

Engineering Contradiction:

Improvecircuit densityVSAvoidsoft error rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

An alpha particle blocking shield is introduced as an intermediary layer between the solder bumps (source of alpha particles) and the sensitive device regions. This shield, formed from conductive material within the wiring structure, intercepts alpha particles before they can reach and disrupt the scaled-down circuit devices, thereby maintaining reliability while allowing continued circuit density improvement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If alpha particle blocking shields are added to prevent soft errors, then reliability improves, but device complexity increases

Engineering Contradiction:

Improvesoft error rateVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The alpha particle blocking shield is merged with the existing wiring structure by forming the shield material as part of the conductive interconnect layers. This integration approach allows the shield to be manufactured using standard wiring fabrication processes, avoiding the need for separate shield manufacturing steps and reducing overall device complexity despite the added protection function.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The conductive material in the wiring structure serves dual functions: it provides electrical interconnection between devices and simultaneously acts as an alpha particle blocking shield. This multi-functionality eliminates the need for dedicated shield materials or structures, thereby maintaining device complexity at acceptable levels while achieving soft error protection.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If alpha particle blocking shields are positioned close to devices for maximum protection, then soft error rate decreases, but manufacturing precision requirements increase

Engineering Contradiction:

Improvesoft error rateVSAvoidshield placement precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The blocking shield is formed preliminarily as part of the wiring structure fabrication process, before final device assembly and testing. By establishing the shield's position and dimensions during the wiring formation stage, the design allows for optimized protection while accommodating standard manufacturing tolerances, reducing the need for ultra-precise post-fabrication adjustments.

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

The alpha particle blocking shields significantly reduce soft error rates by preventing alpha particles from reaching sensitive areas, allowing for increased circuit reliability and performance without affecting the majority of the chip design.

Implementation Method 1

one or more alpha particle blocking shields situated between at least one of the number of devices and a predetermined first location where a terminal pad will be formed in one of the wiring levels

Methodology Applied

Scientific EffectAlpha particle blocking: Absorption (EM radiation)

Data Source

PatentUS8362600B2Method and structure to reduce soft error rate susceptibility in semiconductor structures

Publication Date: 2013.01.29 GLOBALFOUNDRIES US INC

AI summary

A method is disclosed that includes providing a semiconductor substrate having one or more device levels including a number of devices, and forming a number of wiring levels on a top surface of the one or more device levels, wherein one or more of the number of wiring levels includes one or more alpha particle blocking shields situated between at least one of the number of devices and a predetermined first location where a terminal pad will be formed in one of the wiring levels, the one or more alpha particle blocking shields placed at a second location, having one or more widths, and occupying a predetermined number of the wiring levels, sufficient to prevent a predetermined percentage of alpha particles of a selected energy or less expected to be emitted from an alpha particle emitting metallization to be formed adjacent and connected to the terminal pad from reaching the one device.