Wireless Backside Shielding for Chip Attack Detection
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Solution Overview
Problem
Security chips are vulnerable to backside attacks through the silicon substrate, where focused ion beam (FIB) modifications can bypass front surface shields, and existing active shields are difficult to manufacture and detect breaches effectively.
Innovation Solution
A chip security system with a front circuit and a back circuit connected wirelessly, using passive components and resonant circuits to detect breaches in the shielding arrangement, and optionally connecting two chips back-to-back for mutual protection, with a breach-detection circuit to reset the integrated circuit if a breach is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active shield is used to protect the chip from backside attacks, then the security against physical modification is improved, but the manufacturing complexity increases significantly
Solution Approach 1:
The chip is divided into two separate chips, each with its own active shield on opposite sides. This segmentation allows each chip to be manufactured independently with standard processes, avoiding the need for complex through-substrate via fabrication while maintaining security protection.
Solution Approach 2:
A wireless communication interface acts as an intermediary between the two chips, allowing them to coordinate their shield operations without requiring complex physical connections through the substrate. This mediator enables the system to achieve high security while using simpler manufacturing processes.
2Ease of operation
If deep trenches are milled and local thinning is applied to enable backside attack, then access to lower metal layers is achieved, but the chip structure is compromised
Solution Approach 1:
An active shield is implemented on the backside of the chip that detects and responds to attack attempts before they can compromise the chip structure. The shield takes preliminary action to prevent the need for destructive access methods like deep trenching and local thinning.
3Ease of operation
If vias are created to connect the backside shield with the processor, then communication is enabled, but the vias become obvious and prone to attack
Solution Approach 1:
Physical mechanical connections (vias) are replaced with wireless communication between the front and back circuits. This substitution eliminates the vulnerable via structures while enabling the necessary communication for shield operation.
Solution Approach 2:
The connection between front and back circuits is moved from the spatial dimension (physical vias through substrate) to the electromagnetic dimension (wireless communication). This dimensional change allows communication without creating vulnerable physical pathways.
4Ease of operation
If the chip is thinned to 50 or 100 microns using physical grinding, then backside access is facilitated, but the chip becomes more vulnerable to damage
Solution Approach 1:
The active shield on the backside detects and prevents attack attempts before they can exploit chip thinning. This preliminary protective action allows the chip to maintain its structural integrity even when thinned for manufacturing reasons.
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 system effectively prevents backside attacks by wirelessly monitoring the integrity of the shielding arrangement and automatically resetting the chip in case of a breach, enhancing security without the need for complex manufacturing processes.
Implementation Method 1
The antenna wirelessly receives an alternating current signal from the front circuit and provides power to the back circuit
Implementation Method 2
using passive components and resonant circuits to detect breaches in the shielding arrangement
Data Source
AI summary
A system for protecting a chip with an integrated circuit disposed on a first surface, the system including, disposed on the first surface, a first antenna, signal analyzer, chip controller and a signal generator which is operative to supply an outbound signal for transmission by the first antenna, a circuit arrangement, disposed on a second surface of the chip, including a shielding arrangement and a second antenna to receive the outbound signal, the circuit arrangement being operative to transmit a return signal from the second antenna to the first antenna, such that a breach in the shielding arrangement results in a change in, or cessation of, the return signal for detection by the signal analyzer, and a chip controller disposed on the first surface being operative to perform an action on the integrated circuit in response to the detection of the breach. Related apparatus and methods also included.