Wafer Polishing Pressure Conversion for Consistent End Point Detection

Solution Overview

Problem

Conventional polishing apparatuses exhibit variations in measurement results due to fluctuations in mechanical and electrical characteristics, leading to differences in end point detection across multiple units, requiring complex threshold settings and lengthy tuning processes.

Innovation Solution

A polishing apparatus configuration that includes a first electric motor for the polishing table, a second motor for the holding section, a swing arm, and a detection section to generate outputs based on current, torque, and position commands, using data to standardize contact pressure measurements across multiple units, reducing variations in current sensor readings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple polishing apparatuses are used, then productivity is improved, but measurement precision deteriorates due to variations in mechanical and electrical characteristics

Engineering Contradiction:

Improvepolishing throughputVSAvoidend point detection consistency

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent transforms the raw current sensor output into a standardized contact pressure value by changing the parameter representation. Instead of using absolute current values which vary between apparatuses, the system converts current readings into contact pressure values using pre-stored correspondence data, enabling consistent measurement across multiple polishing apparatuses

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary conversion process between the current sensor and the contact pressure measurement. The correspondence data stored in the storage unit acts as a mediator that translates variable electrical characteristics into standardized mechanical pressure values, eliminating direct comparison of apparatus-specific electrical parameters

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If current sensor readings are used directly for end point detection, then device complexity is reduced, but measurement precision deteriorates due to apparatus-specific variations

Engineering Contradiction:

Improvedetection system structureVSAvoidcontact pressure measurement accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary conversion process between the current sensor and the contact pressure measurement. The correspondence data stored in the storage unit acts as a mediator that translates variable electrical characteristics into standardized mechanical pressure values, eliminating direct comparison of apparatus-specific electrical parameters

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent transforms the raw current sensor output into a standardized contact pressure value by changing the parameter representation. Instead of using absolute current values which vary between apparatuses, the system converts current readings into contact pressure values using pre-stored correspondence data, enabling consistent measurement across multiple polishing apparatuses

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If threshold values are adjusted for each polishing apparatus, then measurement precision is improved, but ease of operation deteriorates due to complex tuning requirements

Engineering Contradiction:

Improveend point detection accuracyVSAvoidthreshold setting simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent transforms the raw current sensor output into a standardized contact pressure value by changing the parameter representation. Instead of using absolute current values which vary between apparatuses, the system converts current readings into contact pressure values using pre-stored correspondence data, enabling consistent measurement across multiple polishing apparatuses

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary conversion process between the current sensor and the contact pressure measurement. The correspondence data stored in the storage unit acts as a mediator that translates variable electrical characteristics into standardized mechanical pressure values, eliminating direct comparison of apparatus-specific electrical parameters

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

This configuration standardizes end point detection results across multiple polishing apparatuses, simplifying settings and reducing operational time by ensuring consistent measurements, thereby improving efficiency and accuracy.

Implementation Method 1

a first electric motor that drives to rotate the polishing table, a second electric motor that drives to rotate the holding section, and a third electric motor that swings the swing arm

Methodology Applied

Scientific EffectElectromagnetic force: Electromagnetic Induction

Implementation Method 2

a detection section that detects at least one of a current value of one of the first, second and third electric motors

Methodology Applied

Scientific EffectCurrent detection: Ohm's Law

Data Source

PatentUS12131923B2Polishing apparatus and polishing method

Publication Date: 2024.10.29 EBARA CORP

AI summary

A current detection section detects a current value of a swing shaft motor 14 and generates a first output. A first processing section obtains a contact pressure corresponding to the first output from the first output using first data indicating a correspondence relationship between a contact pressure applied to a semiconductor wafer by a top ring and the first output. A second processing section obtains a second output corresponding to a contact pressure obtained by the first processing section using second data indicating a correspondence relationship between the contact pressure obtained by the first processing section and the second output.