Selective Group IV Semiconductor Deposition Using Group IIIA Halide Dopants

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Solution Overview

Problem

Conventional methods for p-type doping in semiconductor devices, such as CMOS structures, face challenges in achieving high p-type carrier densities without compromising crystalline quality, especially in Group IV semiconductor materials like silicon-germanium, and require complex patterning processes for selective deposition.

Innovation Solution

A method involving the use of Group IIIA halide dopant precursors, such as gallium or aluminum trichloride, in a chemical vapor deposition process to selectively deposit high-p-type doped Group IV semiconductors, allowing for high active carrier concentrations while maintaining crystalline quality and reducing contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If diborane is used for p-type doping in p-type MOS devices, then doping can be achieved, but the method becomes prohibitive for pure Ge layers and high Ge fraction Si1-xGex stressors

Engineering Contradiction:

Improvedoping applicabilityVSAvoidprocess feasibility

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent changes the dopant precursor from diborane to Group IIIA halide dopant precursors (such as aluminum trichloride, gallium trichloride, or indium trichloride). This parameter change enables p-type doping in pure Ge layers and high Ge fraction SiGe stressors where diborane becomes prohibitive, while maintaining process feasibility through chemical vapor deposition

Inventive Principle:

Principle #35Parameter changes

2Quantity of substance

If further boron is added to increase p-type carrier density, then carrier density may increase, but crystalline quality of the doped stressor region declines

Engineering Contradiction:

Improvecarrier densityVSAvoidcrystalline quality

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent changes the dopant element from boron to Group IIIA elements (Al, Ga, In). This parameter change allows achieving high p-type carrier densities (≥1×1020 cm−3) without the crystalline quality degradation that occurs when adding excessive boron to Ge-based materials

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If a continuous Group IV semiconductor layer is deposited and then patterned, then selective deposition can be achieved, but the process becomes time consuming and expensive

Engineering Contradiction:

Improveselective deposition precisionVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent performs preliminary action by incorporating the dopant during the deposition process itself, creating selectively doped regions directly where needed. This eliminates the need for subsequent patterning steps, reducing both processing time and cost while maintaining selective deposition precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent merges the deposition and doping processes into a single simultaneous operation. By co-flowing the Group IV precursor and Group IIIA halide dopant precursor, the material deposition and dopant incorporation occur together, eliminating separate patterning steps

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If conventional doping methods are used, then doping can be achieved, but contact resistance remains high

Engineering Contradiction:

Improvecontact resistanceVSAvoiddoping process simplicity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the dopant type to Group IIIA elements and uses chemical vapor deposition with halide precursors, achieving contact resistivity as low as 0.3 mΩ-cm in highly doped regions. This parameter change improves contact resistance while maintaining process simplicity through a single deposition step

Inventive Principle:

Principle #35Parameter changes

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

Enables high p-type doping densities with improved carrier mobility and reduced contact resistance, facilitating precise selective deposition without the need for additional etchant gases or complex patterning steps.

Implementation Method 1

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

exposing the substrate to at least one Group IIIA halide dopant precursor... enabling high p-type doping densities with improved carrier mobility and reduced contact resistance

Methodology Applied

Scientific EffectDoping: Dopants

Data Source

PatentUS11018002B2Method for selectively depositing a Group IV semiconductor and related semiconductor device structures

Publication Date: 2021.05.25 ASM IP HLDG BV

AI summary

A method for selectively depositing a Group IV semiconductor on a surface of a substrate is disclosed. The method may include, providing a substrate within a reaction chamber and heating the substrate to a deposition temperature. The method may further include, exposing the substrate to at least one Group IV precursor, and exposing the substrate to at least one Group IIIA halide dopant precursor. Semiconductor device structures including a Group IV semiconductor deposited by the methods of the disclosure are also provided.