Flip Chip Semiconductor Back Surface Film with Segmented Laser Transmittance

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Solution Overview

Problem

The existing methods for protecting the back surface of semiconductor chips during laser marking and the dicing process are inefficient, leading to potential damage and increased costs due to the need for additional steps and the risk of chip damage during thinning and miniaturization.

Innovation Solution

A dicing tape-integrated film with a multilayered structure, including a wafer adhesion layer and a laser marking layer, is used, which provides excellent adhesiveness and laser marking properties while integrating with the dicing tape, allowing for protection and marking without damaging the chip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a back surface protective film is attached to protect the semiconductor chip during laser marking, then the chip is protected from damage, but the laser marking property deteriorates due to interference with laser beam transmission

Engineering Contradiction:

Improvechip protectionVSAvoidlaser marking property

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The protective film is divided into two functional layers: a lower layer with high light transmittance (≥40%) that allows laser beam passage for marking, and an upper layer with low light transmittance (<40%) that provides superior chip protection. This segmentation enables each layer to optimize its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the film structure are assigned different optical properties - the lower layer is designed with high transmittance to facilitate laser marking, while the upper layer is designed with low transmittance to enhance protection. This local differentiation of properties resolves the contradiction between protection and marking quality.

Inventive Principle:

Principle #3Local quality

2Reliability

If a separate back surface protective film is attached after dicing, then the chip is protected during thinning and miniaturization, but the number of manufacturing steps increases leading to higher cost

Engineering Contradiction:

Improvechip protection during thinningVSAvoidnumber of manufacturing steps

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The protective film is merged with the dicing tape to form an integrated structure. The dicing tape includes a base material, pressure-sensitive adhesive layer, and the multilayer protective film. This combination eliminates the need for separate protective film attachment steps after dicing, reducing manufacturing complexity while maintaining protection during thinning and miniaturization.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated dicing tape structure serves multiple functions: it provides holding force during dicing, protects the chip back surface during thinning and miniaturization, and eliminates the need for separate protective film attachment. This multi-functionality reduces the overall number of manufacturing steps.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Length of moving object

If the semiconductor chip is thinned for miniaturization, then the device size is reduced, but the chip becomes more susceptible to damage during handling

Engineering Contradiction:

Improvechip thicknessVSAvoidchip strength during handling

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The protective film is attached to the chip back surface before the thinning process begins. This preliminary protection ensures that during subsequent thinning and miniaturization operations, the chip is shielded from damage, allowing aggressive thinning while maintaining handling strength.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The multilayer protective film structure provides beforehand cushioning against mechanical damage. The lower high-transmittance layer and upper low-transmittance layer work together to protect the thinned chip during handling, compensating for the reduced inherent strength of thinner chips.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 film enables effective protection and marking of semiconductor chips during the dicing and flip chip bonding processes, reducing the risk of damage and simplifying the manufacturing steps, while maintaining excellent adhesiveness and appearance properties.

Implementation Method 1

a pressure-sensitive adhesive layer formed on a base material; and a film for flip chip type semiconductor back surface which is formed on the pressure-sensitive adhesive layer

Methodology Applied

Scientific EffectPressure-sensitive adhesion: Adhesive

Implementation Method 2

the laser marking layer has a light transmittance of less than 40% in terms of a light having a wavelength of 532 nm

Methodology Applied

Scientific EffectLaser absorption: Absorption (EM radiation)

Data Source

PatentUS8704382B2Film for flip chip type semiconductor back surface

Publication Date: 2014.04.22 NITTO DENKO CORP

AI summary

The present invention provides a film for flip chip type semiconductor back surface, which is to be formed on a back surface of a semiconductor element flip-chip connected on an adherend, the film including a wafer adhesion layer and a laser marking layer, in which the wafer adhesion layer has a light transmittance of 40% or more in terms of a light having a wavelength of 532 nm and the laser marking layer has a light transmittance of less than 40% in terms of a light having a wavelength of 532 nm.