Silicon Wafer Defect Evaluation via Partial Oxide Film Control

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Solution Overview

Problem

Existing methods for evaluating silicon wafer quality after polishing struggle to distinguish between defects caused by polishing, cleaning, or crystal issues, often degrading surface roughness and failing to detect abnormalities in time, especially since conventional methods like SC1-RT evaluate defects due to crystal or metallic contamination rather than processing defects.

Innovation Solution

A method involving pre and incremental surface defect measurements, alternating ozone water oxidation and hydrofluoric acid oxide film removal treatments without complete oxide film removal, repeated multiple times to isolate and evaluate processing defects like polishing-induced defects, while maintaining surface roughness and controlling oxide film thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional cleaning methods (SC1-RT, complete oxide removal) are used, then defects due to crystal or metallic contamination are evaluated, but processing defects cannot be isolated and surface roughness degrades

Engineering Contradiction:

Improvedefect evaluation accuracyVSAvoidsurface roughness

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The defect evaluation is segmented into two distinct categories: processing defects (polishing-induced) and crystal defects. This is achieved by dividing the cleaning process into controlled oxidation and partial oxide removal steps, allowing selective actualization of processing defects while preserving the oxide film to prevent crystal defect actualization. The measurement process is also segmented into pre-cleaning and post-cleaning measurements to isolate processing defects.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The oxidation state and oxide film thickness are changed as controlled parameters to differentiate between processing defects and crystal defects. By adjusting the oxidation treatment conditions and controlling the oxide film removal to be incomplete, the method creates specific surface states that actualize only processing defects. The HF treatment parameters (concentration, time) are precisely controlled to achieve partial oxide removal without complete film elimination.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If sampling inspection is conducted conventionally, then some quality trends can be followed, but abnormalities in polishing quality cannot be detected timely

Engineering Contradiction:

Improveevaluation efficiencyVSAvoidabnormality detection capability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The method implements feedback through comparative measurement: pre-cleaning defect measurements serve as baseline data, and post-cleaning measurements provide feedback on processing defects. By comparing the two measurement results, abnormalities in polishing quality can be detected timely. The incremental defect measurement approach provides continuous feedback on processing quality trends.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

A pre-cleaning surface defect measurement is performed as a preliminary action before the actual cleaning process. This baseline measurement allows subsequent comparison with post-cleaning measurements to identify processing defects that were present before cleaning but not detected by conventional methods. This preliminary measurement enables early detection of polishing abnormalities.

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 allows for accurate evaluation of processing defects without activating crystal-related defects, enabling timely detection and improvement of polishing quality by observing incremental defect trends, thus ensuring better surface quality and manufacturing precision.

Implementation Method 1

an oxidation treatment by ozone water

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

an oxide film removal treatment by hydrofluoric acid

Methodology Applied

Scientific EffectChemical etching:

Data Source

PatentUS11222780B2Method for evaluating silicon wafer and method for manufacturing silicon wafer

Publication Date: 2022.01.11 SHIN ETSU HANDOTAI CO LTD

AI summary

A method for evaluating a silicon wafer, including: a pre surface defect measuring step for performing a surface defect measurement on the silicon wafer in advance, a cleaning step of alternately repeating on the silicon wafer an oxidation treatment by ozone water and an oxide film removal treatment by hydrofluoric acid under a condition of not completely removing an oxide film formed on a surface of the silicon wafer, and an incremental defect measuring step of performing a surface defect measurement on the silicon wafer after the cleaning step and measuring incremental defects that increased relative to defects measured in the pre surface defect measuring step, wherein the cleaning step and the incremental defect measuring step are alternately performed repeatedly multiple times and the silicon wafer is evaluated based on a measurement result of the incremental defects after each cleaning step.