Reflectometer Feedback for Safe Wafer De-Chucking

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Solution Overview

Problem

Residual electrostatic chucking forces often cause unwanted substrate movement, such as bending, tilting, and breaking, during the de-chucking process in semiconductor processing due to trapped electric charges, which existing technologies fail to adequately detect and mitigate.

Innovation Solution

Employing reflectometers that sense reflected and scattered light to monitor substrate movement and position, allowing for the detection of successful de-chucking and preventing substrate damage by adjusting lift pin forces and detecting potential failures like tilting and lateral slippage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If lift pins are raised to remove substrate from ESC, then substrate de-chucking is achieved, but residual electrostatic forces cause unwanted substrate movement and potential breakage

Engineering Contradiction:

Improvesubstrate de-chucking reliabilityVSAvoidsubstrate movement and breakage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The reflectometer performs preliminary monitoring of substrate position and movement during the de-chucking process, detecting substrate behavior before complete separation occurs. This allows the system to identify potential issues early and adjust lift pin forces accordingly to prevent substrate breakage

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The reflectometer provides real-time feedback on substrate position and movement to the control system. Based on this feedback, the lift pin forces are dynamically adjusted to counteract residual electrostatic forces and prevent unwanted substrate movement, thereby resolving the contradiction between achieving de-chucking and preventing damage

Inventive Principle:

Principle #23Feedback

2Reliability

If residual electrostatic charges are not discharged, then ESC clamping function is maintained, but unwanted substrate movement occurs during de-chucking

Engineering Contradiction:

ImproveESC clamping functionVSAvoidsubstrate removal process

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces direct electrical discharge methods with an optical monitoring system (reflectometer) that detects substrate movement caused by residual electrostatic forces. This substitution allows the system to manage the de-chucking process mechanically through adjusted lift pin forces while using optical feedback, rather than directly manipulating electrical charges

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The reflectometer acts as an intermediary between the ESC and the substrate removal process. It monitors substrate position and provides information that enables indirect control of residual electrostatic effects through lift pin force adjustment, avoiding direct interference with the electrostatic charge while still achieving safe substrate removal

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Effectively prevents substrate breakage and ensures safe removal by confirming successful de-chucking and adjusting lift pin operations based on real-time substrate movement data, reducing the risk of damage and maintaining processing integrity.

Implementation Method 1

a reflectometer to monitor substrate movement. The reflectometer includes a light source to emit light onto a substrate and a detector to receive reflected and scattered light from the substrate

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a reflectometer to monitor substrate movement. The reflectometer includes a light source to emit light onto a substrate and a detector to receive reflected and scattered light from the substrate

Methodology Applied

Scientific EffectScattering: Scattering

Data Source

PatentUS11791189B2Reflectometer to monitor substrate movement

Publication Date: 2023.10.17 LAM RES CORP

AI summary

Various embodiments include a reflectometer and a reflectometry system for monitoring movements of a substrate, such as a silicon wafer. In one embodiment, a reflectometry system monitors and controls conditions associated with a substrate disposed within a process chamber. The process chamber includes a substrate-holding device having an actuator mechanism to control movement of the substrate with respect to the substrate-holding device. The reflectometry system includes a light source configured to emit a beam of light directed at the substrate, collection optics configured to receive light reflected from the substrate by the beam of light directed at the substrate and output a signal related to one or more conditions associated with the substrate, and a processor configured to process the signal and direct the actuator mechanism to control the movement of the substrate with respect to the substrate-holding device based on the signal. Other devices and methods are disclosed.