Specimen Carrier Welding Gap for TEM Sample Alignment

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Solution Overview

Problem

In the semiconductor industry, approximately 20% of samples taken from semiconductor wafers for TEM analysis are lost due to misalignment between the sample and the specimen carrier during the welding process, leading to extra time and damage to wafer sites.

Innovation Solution

The method involves separating the specimen carrier and sample by a gap to prevent displacement, using a continuous body of material deposited from a gas or vapor phase, such as through Electron Beam Induced Deposition (EBID), Ion Beam Induced Deposition (IBID), or Laser Induced Deposition (LID), without direct contact, which maintains the sample's orientation and reduces unwanted material buildup.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the specimen carrier contacts the sample directly during welding, then the welding connection is achieved, but the sample orientation changes and misalignment occurs

Engineering Contradiction:

Improvewelding connection strengthVSAvoidsample orientation precision

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

A gap (intermediary space) is introduced between the specimen carrier and sample during welding. This gap prevents direct contact that would cause displacement, while still allowing material deposition to form a continuous body connecting the two components. The gap acts as a mediator that enables welding without direct mechanical contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The mechanical contact-based welding is replaced by a deposition-based welding process. Instead of pressing the specimen carrier against the sample and using mechanical force for bonding, the method uses deposition of material (e.g., via electron beam induced deposition, ion beam induced deposition, or laser induced deposition) to form a continuous body that connects the specimen carrier and sample without requiring direct mechanical contact.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If the sample is separated completely from the work piece before connection, then the sample can be freely positioned, but alignment with the work piece becomes difficult

Engineering Contradiction:

Improvesample positioning freedomVSAvoidalignment precision

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The specimen carrier is positioned and aligned with the sample before complete separation occurs. The gap is maintained during the deposition process, allowing preliminary positioning and alignment adjustments to be made while the sample is still partially supported by the work piece, ensuring proper alignment before the final connection is established.

Inventive Principle:

Principle #10Preliminary action

3Strength

If material is deposited to connect sample and specimen carrier, then welding is achieved, but unwanted material buildup occurs

Engineering Contradiction:

Improveconnection strengthVSAvoidunwanted material buildup

Core Design Contradiction:

StrengthVSLoss of substance

Solution Approach 1:

The deposition process is localized to the gap region between the specimen carrier and sample. By confining the material deposition to this specific local area, the method achieves effective connection without excessive material buildup in surrounding areas. The deposition is precisely controlled to occur only where needed to form the continuous body.

Inventive Principle:

Principle #3Local quality

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 significantly reduces sample loss by maintaining the sample's orientation and allowing for precise, localized deposition, ensuring proper alignment and efficient thinning for TEM analysis.

Implementation Method 1

irradiating the wafer with a focused beam of e.g. energetic ions, such as a beam of Ga+ ions with an energy of 30 keV. Where the beam impinges upon the wafer, material is removed.

Methodology Applied

Scientific EffectIon beam sputtering: Sputtering

Implementation Method 2

depositing a continuous body of material on sample and specimen carrier... through Electron Beam Induced Deposition (EBID)

Methodology Applied

Scientific EffectElectron beam induced deposition: Electron Beam

Implementation Method 3

depositing a continuous body of material on sample and specimen carrier... through Ion Beam Induced Deposition (IBID)

Methodology Applied

Scientific EffectIon beam induced deposition: Ion Beam

Implementation Method 4

depositing a continuous body of material on sample and specimen carrier... through Laser Induced Deposition (LID)

Methodology Applied

Scientific EffectLaser induced deposition: Laser

Data Source

PatentUS7615745B2Method for separating a minute sample from a work piece

Publication Date: 2009.11.10 FEI CO

AI summary

The invention pertains to a method for separating a minute sample (1) from a work piece (2). Such a method is routinely used in the semiconductor industry to obtain samples from wafers to be inspected in a TEM. It occurred to the inventor that approximately 20% of the obtained samples could not be properly finished (thinned) due to a misalignment of specimen carrier (6) and sample. It turned out that this misalignment is caused by the specimen carrier contacting the sample prior to welding. By not contacting the sample while welding, but leaving a small gap between specimen carrier and sample, this misalignment is avoided. To avoid movement of the specimen carrier during welding, due to e.g. vibration, the specimen carrier can be landed on the wafer on a position (8) close to the sample.