Wafer Annular Projection Removal via Laser Ablation

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Solution Overview

Problem

Existing methods for removing annular projections from semiconductor wafers are prone to damage and require specialized equipment, making it difficult to handle thin wafers effectively during processing.

Innovation Solution

A processing method involving a first tape attaching step, a separating step using a laser beam to cut between the annular projection and the device area, and a removing step to detach the annular projection with a first annular frame, ensuring minimal damage and efficient separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the annular projection is removed by grinding or cutting methods, then the annular projection can be removed from the wafer, but the annular projection is susceptible to damage and the device area may be marred

Engineering Contradiction:

Improveease of annular projection removalVSAvoidintegrity of annular projection and device area

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The wafer is segmented into two parts: the device area and the annular projection. By attaching a tape to the front side of the wafer and mounting it to an annular frame, the annular projection can be separated from the device area without direct mechanical contact that would cause damage. The segmentation allows independent handling of each part during the removal process.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A tape serves as an intermediary between the wafer and the annular frame. The tape is attached to the front side of the wafer and allows the annular projection to be mounted to the frame without direct attachment, preventing damage to the fragile annular projection during the removal process.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If specialized apparatus is used to remove the annular projection, then the annular projection can be removed, but special apparatus for removing the annular projection is required

Engineering Contradiction:

Improvecapability to remove annular projectionVSAvoidcomplexity of removal apparatus

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The annular frame serves multiple functions: it mounts the wafer during processing, supports the annular projection during separation, and facilitates the removal of the annular projection from the device area. This multi-functional design eliminates the need for specialized apparatus dedicated solely to annular projection removal.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The wafer itself provides the mounting mechanism through the tape attached to its front side. The annular projection is removed using the existing wafer structure and tape attachment, without requiring external specialized equipment. The system uses its own components to perform the removal function.

Inventive Principle:

Principle #25Self-service

3Weight of moving object

If the wafer thickness is reduced to achieve miniaturization, then the size and weight of electrical equipment are reduced, but the thin wafer lacks stiffness and is difficult to handle

Engineering Contradiction:

Improveweight of waferVSAvoidstiffness of wafer

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The tape attached to the front side of the thin wafer provides cushioning and support before the wafer is processed. This preliminary protection prevents damage to the fragile thin wafer during handling and mounting, compensating for the lack of inherent stiffness in the reduced-thickness wafer.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The tape acts as an intermediary that provides mechanical support to the thin wafer during handling and mounting operations. This intermediary element compensates for the reduced stiffness of the thin wafer, allowing it to be handled safely despite its minimal thickness.

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

The method allows for easy removal of annular projections without damage, maximizing the effective device area and preventing corrosion, with the laser beam enabling a narrower kerf than traditional cutting blades.

Implementation Method 1

applying a laser beam to the boundary between the annular projection and the device area to cut the wafer and the first tape along the boundary, thereby separating the device area from the annular projection

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS9472442B2Wafer processing method

Publication Date: 2016.10.18 DISCO CORP

AI summary

A wafer processing method which includes a first tape attaching step of attaching a first tape to the front side of a wafer and mounting the wafer through the first tape to a first annular frame, a separating step of holding the wafer through the first tape on a chuck table and applying a laser beam to the boundary between an annular projection formed along the outer circumference of the wafer and a device area surrounded by the annular projection to cut the wafer and the first tape along this boundary, thereby separating the device area from the annular projection, and a removing step of removing the annular projection together with the first annular frame from the device area of the wafer in the condition where the annular projection is supported through the first tape to the first annular frame.