Transistor Source-Drain Doping via Full Amorphization and Laser Annealing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing methods for manufacturing transistors face challenges in achieving uniform doping of source and drain regions over their entire thickness while minimizing thermal budget, particularly for thin semiconductor layers, which can lead to contact resistance variations and non-uniform resistance across transistors.

Innovation Solution

A method involving the complete amorphization of semiconductor regions and surface layers over their entire thickness, followed by nanosecond laser thermal annealing to activate dopants and recrystallize the regions, allowing for improved doping without the need for a crystalline seed, thereby reducing thermal budget and enhancing uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a crystalline seed is kept in the lower portion of semiconductor regions to enable SPER recrystallisation, then dopant activation can be achieved at low temperature, but contact resistance increases and manufacturing precision deteriorates

Engineering Contradiction:

Improvedopant activation temperatureVSAvoiddoping uniformity

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The patent changes the fundamental parameter of recrystallisation mechanism from solid-phase epitaxial regrowth (SPER) requiring a crystalline seed to liquid-phase recrystallisation enabled by nanosecond laser annealing. This allows complete amorphisation followed by uniform doping over the entire thickness, with subsequent laser-induced recrystallisation achieving both low temperature processing and uniform doping distribution without contact resistance issues

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the thermal field-based SPER process with a laser field-based annealing process. The nanosecond laser provides localized, high-energy input that enables rapid melting and recrystallisation without requiring a crystalline seed, substituting the mechanical/thermal gradient-dependent SPER mechanism with a photothermal field-driven process that achieves superior doping uniformity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If complete amorphisation is performed over the entire thickness of semiconductor regions, then doping can be achieved over the entire thickness, but thermal budget increases

Engineering Contradiction:

Improvedoping uniformityVSAvoidthermal budget

Core Design Contradiction:

Manufacturing precisionVSUse of energy by stationary object

Solution Approach 1:

The patent employs periodic pulsed laser annealing with nanosecond duration pulses to achieve recrystallisation. The pulsed nature delivers energy in concentrated bursts that rapidly melt and recrystallise the amorphous semiconductor material, achieving complete doping activation without sustained high-temperature exposure that would increase overall thermal budget

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The nanosecond laser annealing process rushes through the recrystallisation phase extremely quickly, completing the transformation from amorphous to crystalline state in nanosecond timescales. This rapid processing activates dopants throughout the entire thickness without requiring prolonged thermal exposure, effectively skipping through the high-temperature holding phase that would increase thermal budget

Inventive Principle:

Principle #21Skipping (Rushing through)

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 approach enables the production of transistors with improved doping uniformity and reduced resistance across the entire thickness of semiconductor regions, compatible with 3D device manufacturing and reducing thermal stress on the semiconductor material.

Implementation Method 1

carrying out at least one laser thermal annealing by means of one or more laser pulses so as to perform a recrystallisation of the raised regions and of the portions of the surface semiconductor layer while carrying out an activation of dopants

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

laser thermal annealing to activate dopants and recrystallize the regions

Methodology Applied

Scientific EffectThermal annealing: Annealing

Implementation Method 3

making amorphous the raised semiconductor regions and the portions of the surface semiconductor layer located under these raised semiconductor regions over their entire thickness

Methodology Applied

Scientific EffectAmorphisation: Vitrification

Data Source

PatentUS20240203735A1Method for producing doped transistor source and drain

Publication Date: 2024.06.20 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES

AI summary

A method for producing a transistor comprising:providing on a support provided with a surface semiconductor layer and resting on an insulating layer: a gate block, insulating spacers on either side of this gate block, and so-called raised semiconductor regions,making amorphous the raised semiconductor regions and the portions of the superficial semiconductor layer located under these raised semiconductor regions and reaching the insulating layer,doping the raised semiconductor regions and said portions,carrying out a laser heat annealing by means of one or more laser pulses so as to produce a recrystallisation of said raised regions and of said portions while carrying out an activation of dopants in said regions and said portions.