Wafer Back Side Protrusion Handling via Cushioning Layer Embedding

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Solution Overview

Problem

In semiconductor device fabrication, the presence of protrusions on the back side of wafers can lead to increased risk of breakage and misalignment during cutting, resulting in damaged dies or chips due to uneven surface topography.

Innovation Solution

A method involving a protective film and a base sheet with a cushioning layer is applied to the wafer, embedding protrusions and ensuring the back surface of the base sheet is parallel to the wafer's front side, allowing for even pressure distribution and precise cutting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If cutting is performed from the front side of the wafer, then the device area can be processed, but the presence of protrusions on the back side causes misalignment and increased risk of breakage

Engineering Contradiction:

Improvecutting accuracyVSAvoidwafer integrity during cutting

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The method applies preliminary action by attaching a protective film with cushioning layer to the wafer back side before the cutting process. This preparatory step embeds the protrusions in the cushioning layer, creating a flat support surface that prevents misalignment and breakage during subsequent cutting operations from the front side.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective film with cushioning layer acts as an intermediary between the wafer back side and the cutting process. This intermediate structure provides a flat support surface that compensates for the uneven protrusions, enabling precise cutting without direct contact between the cutting tool and the irregular back side features.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If protrusions are present on the back side of the wafer, then specific device structures can be formed, but the risk of wafer breakage and die damage during cutting is significantly increased

Engineering Contradiction:

Improvedevice structure capabilityVSAvoidrisk of breakage and damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The method implements beforehand cushioning by providing a protective film with a cushioning layer that is attached to the wafer back side before cutting. The cushioning layer embeds the protrusions and provides uniform support, preventing breakage and damage during the cutting process while allowing the protrusions to remain intact for their intended device functions.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The method changes the physical state and support parameters of the wafer back side by introducing the protective film and cushioning layer. This transforms the uneven surface with protrusions into a supported structure where the protrusions are embedded and protected, changing the mechanical parameters during cutting to prevent damage.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the back surface of the wafer is uneven due to protrusions, then specific optical or structural elements can be integrated, but the alignment and quality of resulting dies are adversely affected

Engineering Contradiction:

Improveoptical element integrationVSAvoiddie alignment and quality

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The protective film with cushioning layer is applied in advance to create a flat support surface that compensates for the uneven back side. This preliminary action ensures that during cutting, the wafer maintains proper alignment and positioning, resulting in high-quality dies with precise dimensions despite the presence of integrated optical elements or protrusions.

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 method minimizes the risk of wafer breakage and ensures high-quality, well-defined dies or chips by providing a uniform and homogeneous pressure distribution during cutting, while protecting protrusions from damage.

Implementation Method 1

The protective film is adhered to at least a peripheral portion of the second side with an adhesive

Methodology Applied

Scientific EffectAdhesive bonding: Adhesive

Implementation Method 2

providing a uniform and homogeneous pressure distribution during cutting

Methodology Applied

Scientific EffectPressure distribution: Pressure Gradient

Implementation Method 3

The protrusions or projections protruding along the thickness direction of the wafer are embedded in the cushioning layer

Methodology Applied

Scientific EffectMechanical embedding:

Data Source

PatentUS10991612B2Method of processing wafer having protrusions on the back side

Publication Date: 2021.04.27 DISCO CORP

AI summary

A wafer has a first side with a device area comprising a plurality of devices, and a second side opposite to the first side, wherein the second side has a plurality of protrusions protruding along a thickness direction of the wafer. The wafer is processed by providing a protective film and a base sheet having a cushioning layer applied to a front surface thereof, and attaching a front surface of the protective film to the second side of the wafer. The protective film is adhered to at least a peripheral portion of the second side with an adhesive, and a back surface of the protective film opposite to the front surface thereof is attached to the cushioning layer. The protrusions are embedded in the cushioning layer and a back surface of the base sheet is substantially parallel to the first side of the wafer.