Wafer Crystalline Orientation Estimation via Multi-Zone Ion Beam

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Solution Overview

Problem

The semiconductor industry faces challenges in accurately estimating the crystalline orientation angle of semiconductor wafers, which affects the precision of ion implantation and leads to variability in doped regions, particularly in advanced CMOS image sensors where small angle deviations impact device quality and manufacturing efficiency.

Innovation Solution

A method and system for estimating the crystalline orientation angle of a semiconductor wafer using a single test wafer, reducing the influence of angle variability among different wafers and minimizing the number of test wafers required, thereby improving the accuracy of ion implantation and reducing costs by using thermal wave detection and curve fitting to determine the optimal tilt angles for ion beam projection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple test wafers are used to estimate crystalline orientation angle, then measurement reliability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvemeasurement reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple measurement functions into a single test wafer by defining multiple zones (first zone, second zone, third zone) and multiple areas within each zone. This allows estimation of crystalline orientation angles in different directions using one wafer instead of multiple separate test wafers, thereby maintaining measurement reliability while reducing device complexity and cost.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The test wafer is segmented into multiple functional zones (first zone, second zone, third zone) with different area configurations. Each zone is designed to measure specific orientation angles, allowing comprehensive crystalline orientation characterization across different directions using a single divided structure rather than multiple complete wafers.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If multiple test wafers are used to estimate crystalline orientation angle, then measurement precision is improved, but loss of substance increases

Engineering Contradiction:

Improvemeasurement precisionVSAvoidloss of substance

Core Design Contradiction:

Measurement precisionVSLoss of substance

Solution Approach 1:

The patent merges the functionality of multiple test wafers into a single test wafer by incorporating multiple measurement zones that can determine crystalline orientation angles in different directions. This consolidation maintains measurement precision through multi-directional assessment while eliminating the material waste associated with using and discarding multiple test wafers.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If traditional ion implantation methods are used without accurate crystalline orientation estimation, then manufacturing efficiency is maintained, but manufacturing precision deteriorates

Engineering Contradiction:

Improvemanufacturing efficiencyVSAvoidmanufacturing precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary measurement of crystalline orientation angles using the multi-zone test wafer method before conducting the actual ion implantation process. By determining the accurate crystalline orientation in advance, the subsequent ion implantation can be precisely controlled to achieve the desired dopant depth and distribution, thereby improving manufacturing precision without significantly impacting overall manufacturing efficiency.

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

This approach enhances the accuracy of ion implantation, improves the uniformity of semiconductor device quality, and reduces the overhead of wafer quality control, allowing for more precise control of doped regions and reduced costs in estimating crystalline orientation angles.

Implementation Method 1

ion implantation is extensively used to dope impurities into a workpiece, such as a semiconductor wafer

Methodology Applied

Scientific EffectIon implantation: Ion Implantation

Implementation Method 2

using thermal wave detection and curve fitting to determine the optimal tilt angles for ion beam projection

Methodology Applied

Scientific EffectThermal wave detection: Thermal Radiation

Data Source

PatentUS11282707B2Method and system of estimating wafer crystalline orientation

Publication Date: 2022.03.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes: receiving a first wafer; defining a first zone and a second zone on the first wafer and a plurality of first areas; defining a plurality of first areas and second areas for the first and second zones, respectively; projecting first ion beams onto the first areas and receiving first thermal waves in response to the first ion beams; rotating the first wafer by a twist angle; projecting second ion beams onto the second areas and receiving second thermal waves in response to the second ion beams; and estimating a first crystalline orientation angle of the first wafer based on the first and second ion beams and the first and second thermal waves.