Wafer-Platen Optical Alignment for In-Situ Ion Implant Correction

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Solution Overview

Problem

Current semiconductor processing systems lack effective in-situ methods for verifying and correcting the proper positioning of wafers atop platens within processing chambers, leading to potential misalignment and defects during fabrication.

Innovation Solution

A system and method utilizing external imaging devices and illumination sources to detect the perimeter edges and positioning notches of both the platen and wafer, with a controller determining position data and adjusting the wafer's position for accurate alignment, employing backlighting to enhance visual contrast and minimize reflection issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional mechanical or vacuum chucking methods are used to hold the wafer on the platen, then the wafer can be retained during processing, but the wafer may become mispositioned relative to the platen center

Engineering Contradiction:

Improvewafer retentionVSAvoidwafer positioning accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The system performs preliminary detection of platen position and wafer alignment using an external imaging device before the actual ion implantation process. The controller calculates position data and determines corrective actions in advance, allowing the wafer to be repositioned before processing begins, thus preventing misalignment issues during the critical implantation step

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements a feedback loop where the imaging device continuously monitors wafer position on the platen, the controller processes this visual data to determine alignment status, and corrective actions are automatically applied. This closed-loop control ensures the wafer maintains proper positioning throughout the processing sequence

Inventive Principle:

Principle #23Feedback

2Device complexity

If no in-situ verification system is implemented, then the processing chamber remains simple and cost-effective, but wafer misalignment and processing defects cannot be detected or corrected

Engineering Contradiction:

Improveprocessing chamber simplicityVSAvoidwafer alignment accuracy

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

An external imaging device is introduced as an intermediary component that observes the platen and wafer through the chamber window without physically interfering with the processing environment. This allows verification and correction capabilities to be added while maintaining the fundamental simplicity and vacuum integrity of the processing chamber design

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces complex mechanical measurement and adjustment mechanisms with an optical-based imaging and control system. The imaging device captures visual data, and the controller processes this information to determine positional corrections, substituting mechanical complexity with optical-electronic systems that provide higher precision with fewer moving parts

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Illumination intensity

If illumination is provided from within the chamber, then the platen and wafer can be visualized, but reflections and glare may interfere with accurate position detection

Engineering Contradiction:

Improveplaten visibilityVSAvoidedge detection accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

Instead of illuminating from within the chamber as traditionally done, the system inverts the approach by positioning the illumination source and imaging device outside the chamber. Light is directed through the chamber window from the external side, eliminating internal reflections and providing clear, glare-free images of the platen and wafer for accurate position detection

Inventive Principle:

Principle #13The other way round (Inversion)

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

Ensures precise wafer alignment, reducing misalignment errors, improving uniformity of ion exposure processes, and enhancing semiconductor device performance by correcting wafer-to-wafer variations and defects.

Implementation Method 1

employing backlighting to enhance visual contrast and minimize reflection issues

Methodology Applied

Scientific EffectBacklighting: Light

Implementation Method 2

detecting a perimeter edge of the platen using an imaging device positioned external to the chamber

Methodology Applied

Scientific EffectOptical imaging: Photography

Data Source

PatentUS20240412997A1High-precision in-situ verification and correction of wafer position and orientation for ion implant

Publication Date: 2024.12.12 APPLIED MATERIALS INC

AI summary

Disclosed herein are approaches for in-situ verification and correction of a wafer position. In one approach, a method may include illuminating an underside of a platen positioned within a processing chamber, and detecting a perimeter edge of the platen using an imaging device positioned external to the processing chamber, above the platen. The method may further include determining, via a controller, position data for the platen based on the detected perimeter edge of the platen, and positioning a wafer atop the platen based on the position data of the platen, wherein the wafer comprises a positioning notch. The method may further include detecting a position of the wafer and a position of the positioning notch using the imaging device, and comparing the position data of the platen to the detected position of the wafer and comparing the detected position of the positioning notch to an expected notch position