Capacitive Probe Assembly for Non-Destructive Buried Layer Characterization
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Solution Overview
Problem
Existing methods for characterizing electrical conductivity of buried conducting layers in semiconductor substrates are limited by the need for alloyed ohmic contacts, which can be time-consuming, destructive, and require different recipes for n- and p-type doped systems, and often damage the samples, making them unsuitable for reuse.
Innovation Solution
A probe assembly using capacitive contacts that capacitively couple with buried conducting layers without physical contact, employing a conductive depletion gate to deplete electron regions and allow for non-invasive four-point conductance measurements, enabling characterization without ohmic contacts and sample damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alloyed ohmic contacts are used for four-point electrical characterization of buried conducting layers, then electrical conductivity can be measured, but the sample cannot be reused and fabrication time increases
Solution Approach 1:
The patent replaces the mechanical/procedural approach of forming physical ohmic contacts through alloying and sputtering with an electrical field-based approach. Capacitive probes are used to induce transient ohmic contact through electric field coupling, eliminating the need for permanent physical contacts and reducing fabrication time while enabling non-destructive measurement.
Solution Approach 2:
The patent changes the electrical parameters by applying AC voltage at specific frequencies to create capacitive coupling. By varying the frequency and voltage parameters, the system achieves transient ohmic contact without permanent modification, allowing rapid measurement without sample destruction or prolonged fabrication processes.
2Measurement precision
If alloyed ohmic contacts are formed with buried conducting layers, then electrical characterization is enabled, but different alloy recipes are needed for n- and p-type doped systems
Solution Approach 1:
The patent creates a universal measurement approach using capacitive probes that work for both n-type and p-type doped semiconductor layers without requiring different alloy recipes. The same capacitive coupling mechanism and probe configuration can characterize different doped types by adjusting electrical parameters, eliminating the need for multiple specialized contact fabrication processes.
3Measurement precision
If probes physically contact the sample to measure electrical properties, then measurements can be taken, but the sample is scratched and cannot be reused
Solution Approach 1:
The patent replaces direct mechanical contact with electrical field-based measurement. Capacitive probes couple to the buried conducting layer through electric fields without physical touch, eliminating scratching and mechanical damage while enabling non-destructive characterization that allows sample reuse.
Solution Approach 2:
The patent introduces an intermediary approach using capacitive coupling as a mediator between the probe and the buried conducting layer. The capacitive interface allows electrical energy transfer without direct physical contact, serving as a non-invasive bridge that enables measurement while protecting the sample from mechanical damage.
4Measurement precision
If ohmic contacts are formed permanently, then electrical characterization is achieved, but the sample is altered and cannot be reused for other purposes
Solution Approach 1:
The patent introduces dynamic, transient ohmic contact through capacitive coupling that exists only during measurement. The contact is not permanent but dynamically created through applied voltage and frequency, allowing the sample to return to its original state after measurement and be reused for other purposes without compositional alteration.
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 efficient, non-destructive characterization of buried conducting layers, allowing samples to be reused and providing high-resolution measurements of charge carrier mobility and density without the need for sample preparation or ohmic contacts.
Implementation Method 1
capacitive contacts that capacitively couple with buried conducting layers without physical contact
Implementation Method 2
conductive depletion gate to deplete electron regions and allow for non-invasive four-point conductance measurements
Data Source
AI summary
A probe assembly includes plural capacitive contacts that are separate from each other and a conductive depletion gate disposed between and separating the contacts from each other. The depletion gate is configured to receive a direct electric voltage to deplete regions of a sample under test of electrons. The contacts are configured to be placed in close proximity to a buried conducting layer in the sample under test without engaging the buried conducting layer, thereby capacitively coupling to the buried conducting layer. A first subset of the capacitive contacts is configured to apply an alternating electric current to a portion of the sample under test and a second subset of the capacitive contacts is configured to sense an alternating voltage response of the portion of the sample under test to characterize one or more electrical properties of the sample under test without the capacitive contact with the buried conductive layer.