Neutron-Absorbing Passivation Layer for Digital Circuit SER Reduction

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Solution Overview

Problem

Digital integrated circuits are susceptible to soft errors caused by radiation, electromagnetic interference, and electrical noise, particularly due to alpha particles, cosmic rays, and neutron-induced boron fission, which can corrupt data without damaging the device.

Innovation Solution

Incorporating thermal neutron absorbing materials like Gd, Sm, Cd, or combinations thereof into passivation, polyimide, and oxide layers using Chemical Vapor Deposition or implantation to reduce soft error rates by blocking alpha particles and thermal neutrons.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If BPSG is used in chip fabrication, then manufacturing process is simplified, but soft error rate increases due to boron fission

Engineering Contradiction:

Improvefabrication processVSAvoidsoft error rate

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by selectively doping specific regions of the passivation layer with neutron-absorbing materials (gadolinium, samarium, or cadmium) at concentrations of 1-100 atoms/cm³, while leaving other regions undoped. This localized approach reduces soft errors from boron fission in critical areas without requiring complete process redesign, thus maintaining manufacturing simplicity while improving reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent creates a composite passivation layer structure combining conventional BPSG material with embedded neutron-absorbing materials (gadolinium, samarium, or cadmium). This composite structure maintains the beneficial fabrication properties of BPSG while adding neutron absorption capability to reduce boron fission-induced soft errors, resolving the contradiction between ease of manufacture and reliability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If passivation layers are doped with thermal neutron absorbing materials, then soft error rate decreases, but device complexity increases

Engineering Contradiction:

Improvesoft error rateVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the protection function against neutron-induced soft errors directly into the existing passivation layer structure by doping it with neutron-absorbing materials. Instead of adding separate protection layers or structures, the protective function is combined with the conventional passivation layer, reducing overall device complexity while maintaining reliability improvements.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If neutron-absorbing materials are added to protection layers, then radiation-induced charge generation is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improveradiation resistanceVSAvoiddoping concentration control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent specifies precise doping concentration ranges (1-100 atoms/cm³) for neutron-absorbing materials in the passivation layer and provides guidance for controlling these parameters during fabrication. By establishing specific parameter windows and control methods, the patent enables manufacturers to achieve the desired radiation protection while maintaining feasible manufacturing precision standards.

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

The doping of thermal neutron absorbing materials in protection layers effectively reduces the soft error rate in digital circuits by mitigating the impact of radiation-induced charge generation, enhancing the reliability of integrated circuits.

Implementation Method 1

Methodology Applied

Scientific EffectNeutron absorption: Absorption (physical)

Implementation Method 2

The doping of thermal neutron absorbing materials in protection layers effectively reduces the soft error rate in digital circuits by mitigating the impact of radiation-induced charge generation

Methodology Applied

Scientific EffectAlpha particle stopping: Absorption (physical)

Implementation Method 3

Incorporating thermal neutron absorbing materials like Gd, Sm, Cd, or combinations thereof into passivation, polyimide, and oxide layers using Chemical Vapor Deposition or implantation

Methodology Applied

Scientific EffectChemical Vapor Deposition: Chemical Vapour Deposition

Data Source

PatentUS8946874B2IC in-process solution to reduce thermal neutrons soft error rate

Publication Date: 2015.02.03 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Integrated Circuits and methods for reducing thermal neutron soft error rate (SER) of a digital circuit are provided by doping a protection layer on top of the metal layer and in physical contact with the metal layer of the digital circuit, wherein the protection layer is doped with additional thermal neutron absorbing material. The thermal neutron absorbing material can be selected from the group consisting of Gd, Sm, Cd, B, and combinations thereof. The protection layer may comprise a plurality of sub-layers among which a plurality of them containing additional thermal neutron absorbing material.