Security Chip with Roughened Medium Layer for Laser Attack Resistance

Solution Overview

Problem

Existing security chips are vulnerable to laser attacks, particularly laser fault injection methods, which can compromise secret keys due to the reflection of light on metal layers, and current solutions that incorporate photosensitive modules to mitigate this issue increase chip area and costs.

Innovation Solution

A security chip design featuring a first medium layer with a roughened surface that is optically denser than a second medium layer, causing light to be totally reflected or scattered, thereby preventing laser attacks without occupying additional chip area, utilizing a substrate formed by these layers and a semiconductor chip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a photosensitive module is added to detect laser attacks, then security against laser attacks is improved, but chip area and manufacturing cost increase

Engineering Contradiction:

Improvesecurity against laser attacksVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent converts the harmful reflection effect of metal layers on lasers into a beneficial security feature. By intentionally designing a rough upper surface on the first medium layer, incident laser light is scattered and totally reflected before reaching the semiconductor chip, transforming what was previously an attack vulnerability into an active defense mechanism that requires no additional components or chip area.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the physical parameter of the medium layer surface from smooth to rough (with roughness greater than or equal to a preset threshold). This parameter change fundamentally alters the optical interaction with incident light, causing scattering and total reflection that prevent laser attacks without requiring additional photosensitive detection modules.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a photosensitive module is added to detect laser attacks, then security against laser attacks is improved, but manufacturing cost increases

Engineering Contradiction:

Improvesecurity against laser attacksVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent converts the harmful reflection effect of metal layers on lasers into a beneficial security feature. By intentionally designing a rough upper surface on the first medium layer, incident laser light is scattered and totally reflected before reaching the semiconductor chip, transforming what was previously an attack vulnerability into an active defense mechanism that requires no additional components or chip area.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the physical parameter of the medium layer surface from smooth to rough (with roughness greater than or equal to a preset threshold). This parameter change fundamentally alters the optical interaction with incident light, causing scattering and total reflection that prevent laser attacks without requiring additional photosensitive detection modules.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the upper surface of the first medium layer is made rough to scatter light, then laser attack resistance is improved, but light intensity reaching the chip is reduced

Engineering Contradiction:

Improvelaser attack resistanceVSAvoidlight intensity reaching the chip

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent applies a localized rough surface treatment only to the upper surface of the first medium layer, while keeping the rest of the structure intact. This localized modification selectively scatters and reflects incident laser light from the back side, while normal operational light signals from the front side remain unaffected, thus achieving security without compromising functionality.

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

Effectively reduces the intensity of light reaching the logic or storage areas of the security chip, preventing laser attacks while maintaining a simple process flow suitable for mass production and not affecting existing chip processing methods.

Implementation Method 1

a roughness of an upper surface of the first medium layer is greater than or equal to a preset threshold, so that light entering the second medium layer from the first medium layer is able to be totally reflected

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

light entering the second medium layer from the first medium layer is able to be totally reflected and/or scattered

Methodology Applied

Scientific EffectLight scattering: Scattering

Data Source

PatentUS11462490B2Security chip, security chip production method and electronic device

Publication Date: 2022.10.04 SHENZHEN GOODIX TECH CO LTD

AI summary

A security chip includes: a first medium layer; a second medium layer disposed on the first medium layer, where the first medium layer is an optically denser medium relative to the second medium layer, and a roughness of an upper surface of the first medium layer is greater than or equal to a preset threshold, so that light entering the second medium layer from the first medium layer is able to be totally reflected and/or scattered; and a semiconductor chip disposed on the second medium layer. Based on the above technical solution, light incident from a lower surface of the first medium layer is able to be totally reflected or scattered by the upper surface of the first medium layer, so that most of light cannot reach a logic or storage area on the front of the security chip, thereby achieving the purpose of resisting a laser attack.