Standard Reference Die Generation for Wafer Inspection

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Solution Overview

Problem

Current semiconductor manufacturing processes face challenges in detecting systematic and repeater defects due to limitations in existing inspection techniques, such as die-to-die inspection, which cannot accurately identify defects that occur in both test dies, and die-to-standard reference die inspection, which is complicated by differences between test and standard reference dies, leading to reduced accuracy in defect detection.

Innovation Solution

A computer-implemented method for generating a standard reference die by combining the output of an inspection system for a centrally located die and one or more dies on a wafer, based on within-die positions, to create an image with reduced noise from random defects, allowing for accurate detection of repeater defects through alignment with design data space and comparison using adaptive thresholding or histogram equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If die-to-die inspection is used to detect defects, then random defects can be detected, but systematic and repeater defects cannot be detected

Engineering Contradiction:

Improvedefect detection capabilityVSAvoidability to detect different defect types

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent introduces a standard reference die as an intermediary element that mediates between multiple test dies. This reference die serves as a common comparison target that enables detection of both random defects (by comparing individual dies to reference) and systematic defects (by analyzing patterns across multiple dies using the reference as baseline), thereby resolving the limitation of die-to-die inspection

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If die to standard reference die inspection is used, then systematic defects can be detected, but the process is complicated by differences between test die and standard reference die such as color variations and alignment accuracy

Engineering Contradiction:

Improvesystematic defect detectionVSAvoidinspection process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting inspection parameters such as threshold values, alignment tolerances, and comparison criteria based on the specific characteristics of each test die and reference die. This allows the system to adapt to color variations and alignment differences without requiring complex manual calibration, simplifying the inspection process while maintaining systematic defect detection capability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary actions by pre-processing the test die and reference die data to correct for known issues such as color variations and alignment offsets before comparison. This includes preliminary alignment routines and normalization of image parameters, which eliminates the need for complex real-time adjustments during the inspection process

Inventive Principle:

Principle #10Preliminary action

3Reliability

If standard reference die is acquired for inspection, then repeater defects can be detected, but it is difficult to acquire a suitable standard reference die

Engineering Contradiction:

Improverepeater defect detectionVSAvoidease of acquiring standard reference die

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent implements self-service by enabling the inspection system to automatically generate and update the standard reference die from the inspected wafers themselves. The system identifies suitable reference dies from production wafers, processes them into a standardized reference, and stores it for future comparisons. This eliminates the need for manual acquisition and preparation of standard reference dies by external personnel

Inventive Principle:

Principle #25Self-service

4Measurement precision

If multiple dies are combined to generate standard reference die, then noise from random defects is reduced, but the combining process requires precise alignment based on within die positions

Engineering Contradiction:

Improvenoise reduction in standard reference dieVSAvoidalignment precision of within die positions

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent performs preliminary alignment actions by pre-establishing a standardized coordinate system and position mapping for multiple dies before combining them. Alignment marks and reference features are identified and registered in advance, creating a template for positioning that simplifies the subsequent combining process and ensures consistent alignment precision across all combined dies

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8204296B2Methods for generating a standard reference die for use in a die to standard reference die inspection and methods for inspecting a wafer

Publication Date: 2012.06.19 KLA CORP

AI summary

Methods for generating a standard reference die for use in a die to standard reference die inspection and methods for inspecting a wafer are provided. One computer-implemented method for generating a standard reference die for use in a die to standard reference die inspection includes acquiring output of an inspection system for a centrally located die on a wafer and one or more dies located on the wafer. The method also includes combining the output for the centrally located die and the one or more dies based on within die positions of the output. In addition, the method includes generating the standard reference die based on results of the combining step.