Strained NMOS and PMOS Layout for Opposing Channel Stress

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Solution Overview

Problem

Existing methods struggle to simultaneously produce N-channel and P-channel MOS transistors with different stress constraints, particularly in small dimensions, which hinders performance improvement in semiconductor-on-insulator structures.

Innovation Solution

A method for manufacturing N-channel and P-channel MOS transistors with different constraints by forming insulated grids on transverse trenches, connecting transistors to high and low supply potentials, and applying stress layers using silicon nitride and silicon-germanium to achieve desired stress conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If known processes are used to simultaneously produce P-channel and N-channel transistors, then both transistor types can be manufactured, but it is difficult to reconcile different stress constraints for each type, particularly in small dimensions

Engineering Contradiction:
Improveability to provide different stress constraints for N-channel and P-channel transistorsVSAvoidprocess complexity for simultaneous production of differently constrained transistors
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The substrate is divided into two separate bands: a first band for N-channel transistors and a second band for P-channel transistors. Each band receives tailored stress layers appropriate for its transistor type, allowing different stress constraints to be applied simultaneously without process reconciliation issues.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different stress layer configurations are applied to different regions of the substrate. The first band receives a stress layer configuration optimized for N-channel transistors (tensile stress), while the second band receives a configuration optimized for P-channel transistors (compressive stress), enabling locally optimized performance.

Inventive Principle:
Principle #3Local quality

2Speed

If stress layers are applied to improve transistor performance, then transistor speed and performance are enhanced, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvetransistor operation speedVSAvoidease of applying different stress layers to different bands
Core Design Contradiction:
SpeedVSEase of manufacture

Solution Approach 1:

The manufacturing process segments the substrate into distinct bands early in the process, allowing stress layers to be applied independently to each band. This segmentation simplifies the overall manufacturing complexity by treating each band as a separate manufacturing zone with its own optimized process parameters.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stress layers are applied to the semiconductor layer before certain subsequent processing steps. This preliminary application of stress layers ensures that the performance-enhancing stress is established early in the manufacturing process, allowing subsequent steps to proceed without disrupting the stress configuration.

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 method enables the production of fast N-channel and P-channel transistors with opposing stress constraints, resulting in enhanced performance and speed of integrated circuits.

Implementation Method 1

perform a heat treatment to relax the stress layer, adapted to retain at least some of the stresses of the tape and slabs

Methodology Applied
Scientific EffectStress relaxation: Stress Relaxation

Implementation Method 2

the stress layer is made of silicon nitride formed in step a) by plasma-assisted chemical vapor deposition

Methodology Applied
Scientific EffectPlasma-enhanced chemical vapor deposition: Plasma Enhanced Chemical Vapour Deposition

Implementation Method 3

perform a heat treatment to relax the stress layer, adapted to retain at least some of the stresses of the tape and slabs

Methodology Applied
Scientific EffectThermal relaxation: Heat Treatment

Implementation Method 4

the stress layer is made of silicon-germanium and is epitaxially grown in step a) on the substrate

Methodology Applied
Scientific EffectEpitaxial growth: Epitaxy

Data Source

PatentEP3401953B1Chip with strained nmos and pmos transistors
Publication Date: 2026.02.18 STMICROELECTRONICS (CROLLES 2) SAS
  • EP3401953B1 patent drawingFigure 1A~1D
  • EP3401953B1 patent drawingFigure 2A~2D
  • EP3401953B1 patent drawingFigure 3A~3D

AI summary

The invention relates to an electronic chip comprising an insulating layer on a substrate; longitudinal trenches (250L) between and on either side of first (54N) and second (54P) strips side by side; transverse trenches (250W) from one edge to the other of the first strip, extending through the insulating layer and into the substrate, the insulating layer of the first strip being covered, between the transverse and longitudinal trenches, with semiconductor slabs (260) strained in tension, and the insulating layer of the second strip being covered, facing the slabs and between the longitudinal trenches, with semiconductor portions of a ribbon (252) strained in longitudinal compression and/or in transverse tension ; and N-channel MOS transistors being located, in the first strip, in and on the plates and P-channel MOS transistors being located, in the second strip, in and on said ribbon portions.