BEOL NEMS Power Gating for Zero-Leakage IC Switching

Solution Overview

Problem

Existing power gating techniques in integrated circuits (ICs) face challenges such as increased footprint in the front end of line (FEOL) portions of the IC, leakage current in the off state, and headroom loss due to the use of n-type or p-type transistors.

Innovation Solution

The integration of nanoelectromechanical systems (NEMS) devices in the back end of line (BEOL) for power gating, which eliminates the need for gating transistors in the FEOL, reduces leakage current due to mechanical switching, and avoids headroom loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If gating transistors are used for power gating, then power leakage is reduced, but footprint area in FEOL increases

Engineering Contradiction:

Improvepower leakageVSAvoidfootprint area

Core Design Contradiction:

Loss of energyVSArea of stationary object

Solution Approach 1:

The patent moves the power gating function from the FEOL (front end of line) to the BEOL (back end of line) by using nanoelectromechanical switches instead of transistor-based gates. This dimensional shift in the manufacturing process layers eliminates the need for additional FEOL footprint while achieving power gating functionality.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent replaces the electrical transistor-based gating mechanism with a nanoelectromechanical switch system. The NEMS device uses mechanical movement of a beam to open or close contacts, substituting the electrical field-effect transistor mechanism with a purely mechanical switching action that achieves isolation without requiring FEOL transistor footprint.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If gating transistors are used for power gating, then power leakage is reduced, but leakage current in off state persists

Engineering Contradiction:

Improvepower leakageVSAvoidleakage current in off state

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent replaces the electrical transistor-based gating mechanism with a nanoelectromechanical switch system. The NEMS device uses mechanical movement of a beam to open or close contacts, substituting the electrical field-effect transistor mechanism with a purely mechanical switching action that achieves isolation without requiring FEOL transistor footprint.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the gating function from the transistor domain and implements it separately using NEMS technology. By taking out the power gating function from the FEOL transistor layer and implementing it in the BEOL with mechanical switches, the system achieves near-zero leakage current since the mechanical contacts can be fully opened to break the current path completely.

Inventive Principle:

Principle #2Taking out (Extraction)

3Power

If n-type transistors are used for power gating, then driving capability is improved, but headroom loss occurs

Engineering Contradiction:

Improvedriving capabilityVSAvoidheadroom loss

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

The patent replaces the electrical transistor-based gating mechanism with a nanoelectromechanical switch system. The NEMS device uses mechanical movement of a beam to open or close contacts, substituting the electrical field-effect transistor mechanism with a purely mechanical switching action that achieves isolation without requiring FEOL transistor footprint.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This solution reduces the footprint in the FEOL, eliminates leakage current in the off state, and maintains performance without headroom loss, thereby enhancing the efficiency and compatibility of power gating in ICs.

Implementation Method 1

a control electrode operable to move the movable feature relative to the first electrode

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS20250056874A1Power gating using nanoelectromechanical systems (NEMS) in back end of line (BEOL)

Publication Date: 2025.02.13 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

One aspect of the present disclosure pertains to a device. The device includes a substrate, a logic circuit disposed on the substrate, and a nanoelectromechanical systems (NEMS) device electrically connected to the logic circuit and formed on the substrate. The NEMS device includes a first electrode electrically connected to the logic circuit, a second electrode electrically connected to a first power supply, a movable feature electrically connected to the second electrode, and a control electrode operable to move the movable feature relative to the first electrode.