Semiconductor Doping via Hydrogen Donor Dissociation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The high cost and axial inhomogeneity of silicon ingots produced by existing methods for manufacturing power semiconductor devices with high blocking capability, as well as the expense of epitaxial growth for drift zones, necessitate a more efficient method for achieving desired dopant concentrations in semiconductor substrates.

Innovation Solution

A method involving the generation of crystal lattice defects and hydrogen-related donors in a semiconductor substrate, followed by a heat treatment to control the cumulative dopant concentration, allowing for a final dopant concentration within 15% of a target value, utilizing a main temperature profile determined by the dissociation rate of hydrogen-related donors, regardless of oxygen and carbon content.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If epitaxial growth is used to form drift zones, then dopant distribution homogeneity is improved, but manufacturing cost increases

Engineering Contradiction:

Improvedopant distribution homogeneityVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the doping mechanism from in-situ epitaxial doping to post-growth hydrogen-related donor formation through heat treatment. By controlling temperature parameters during heat treatment, the dopant concentration is adjusted after the drift zone is already formed, achieving homogeneous distribution without the high cost of epitaxial doping processes.

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If silicon ingots are grown by Czochralski process, then wafer diameter is increased beyond 12 inches, but axial dopant inhomogeneity worsens

Engineering Contradiction:

Improvewafer diameterVSAvoidaxial dopant inhomogeneity

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent segments the doping process into two independent stages: (1) drift zone formation through float zone or Czochralski processes, and (2) dopant concentration adjustment through post-growth heat treatment. This segmentation allows large diameter wafers to be produced while axial inhomogeneity is corrected in the second stage via controlled hydrogen donor dissociation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary drift zone formation with excess dopant concentration, then uses subsequent heat treatment to dissociate hydrogen-related donors and achieve the target concentration. This preliminary action allows the use of simpler, more cost-effective growth processes for large diameter wafers while maintaining precision through controlled post-processing.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If float zone melting is used to grow silicon ingots, then axial dopant homogeneity is improved, but manufacturing cost increases and maximum wafer diameter is limited to 12 inches

Engineering Contradiction:

Improveaxial dopant homogeneityVSAvoidmanufacturing cost and wafer size limitation

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent changes the state of dopants from being fixed during growth to being adjustable through post-growth heat treatment. By controlling the temperature profile during heat treatment, the dissociation rate of hydrogen-related donors is adjusted to achieve precise dopant concentration control, enabling cost-effective production of large diameter wafers with homogeneous doping.

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

This approach enables the production of semiconductor devices with a dopant concentration range of 1E12 cm−3 to 1E17 cm−3, with hydrogen-related donors comprising at least 25% of extrinsic donors, improving manufacturing efficiency and reducing costs by eliminating the need for precise oxygen and carbon content knowledge.

Implementation Method 1

generating crystal lattice defects in a horizontal surface portion of a semiconductor substrate and forming hydrogen-related donors in the surface portion

Methodology Applied

Scientific EffectCrystal lattice defects:

Implementation Method 2

a main temperature profile is determined for dissociating a defined portion of the hydrogen-related donors. The semiconductor substrate is subjected to a main heat treatment applying the main temperature profile

Methodology Applied

Scientific EffectDissociation rate: Thermolysis

Data Source

PatentUS10128328B2Method of manufacturing semiconductor devices and semiconductor device containing hydrogen-related donors

Publication Date: 2018.11.13 INFINEON TECHNOLOGIES AG

AI summary

Crystal lattice defects are generated in a horizontal surface portion of a semiconductor substrate and hydrogen-related donors are formed in the surface portion. Information is obtained about a cumulative dopant concentration of dopants, including the hydrogen-related donors, in the surface portion. Based on the information about the cumulative dopant concentration and a dissociation rate of the hydrogen-related donors, a main temperature profile is determined for dissociating a defined portion of the hydrogen-related donors. The semiconductor substrate is subjected to a main heat treatment applying the main temperature profile to obtain, in the surface portion, a final total dopant concentration deviating from a target dopant concentration by not more than 15%.