Backside Infrared Laser Fusing for Semiconductor Workpieces

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Solution Overview

Problem

Conventional laser fusing methods are incompatible with modern low-k or ultra-low-k dielectrics, leading to delamination, exposure of fuses, corrosion risks, and increased processing costs, with large fuse pitch requirements and extra processing steps.

Innovation Solution

A method involving an infrared laser beam to fuse silicide-based laser fuses from the back side of a semiconductor workpiece, maintaining structural integrity and allowing for stealth dicing using the same laser, reducing area consumption and avoiding humidity exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional laser fusing methods are used, then fusing can be achieved, but delamination occurs and modern low-k or ultra-low-k dielectrics are damaged

Engineering Contradiction:

Improvefuse integrityVSAvoiddelamination and dielectric damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies backside irradiation instead of conventional frontside laser fusing. The laser beam is directed from the backside of the substrate through the substrate to fuse the fuse structure, which prevents direct thermal exposure of the dielectric layers and eliminates delamination issues while enabling compatibility with modern low-k and ultra-low-k dielectrics

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If conventional laser fusing is used, then fusing can be achieved, but fuse exposure and corrosion risks occur

Engineering Contradiction:

Improvefuse functionalityVSAvoidcorrosion and exposure

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

By irradiating from the backside, the fuse is melted and fused while remaining embedded within the substrate structure. The fuse material is drawn into the substrate or forms a fused bridge that remains enclosed, preventing exposure to ambient humidity and eliminating corrosion risks

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

If conventional laser fusing methods are used, then fusing can be achieved, but additional processing steps and equipment are required

Engineering Contradiction:

Improvefuse fusingVSAvoidprocessing steps and equipment

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The backside irradiation laser system serves dual purposes: it performs fuse fusing by melting the fuse material and simultaneously creates a modified region in the substrate that enables stealth dicing. This eliminates the need for separate processing steps and equipment for both fusing and dicing operations

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the fuse fusing process and stealth dicing process into a single integrated operation using backside laser irradiation. The same laser beam and processing step achieve both objectives, reducing manufacturing complexity and cycle time

Inventive Principle:

Principle #5Merging (Combining)

4Reliability

If conventional laser fusing is used, then fusing can be achieved, but large fuse pitch is required

Engineering Contradiction:

Improvefuse operationVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Backside irradiation enables precise localization of energy deposition at the fuse position through the substrate. The laser can be focused to a small spot size and accurately positioned, allowing tight fuse pitch and high-density fuse arrays without the need for large separation distances required by frontside methods

Inventive Principle:

Principle #13The other way round (Inversion)

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

Enables compatible laser fusing with modern dielectrics, reduces damage and corrosion risks, and integrates fusing and dicing processes, lowering costs and improving chip area efficiency.

Implementation Method 1

fusing the at least one laser fuse from a back side of the substrate region by means of an infrared laser beam

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

irradiating the back side of the semiconductor workpiece with an infrared laser beam focused onto the interface

Methodology Applied

Scientific EffectInfrared radiation absorption: Absorption (EM radiation)

Implementation Method 3

infrared laser beam focused onto the interface between the substrate region and the functional region

Methodology Applied

Scientific EffectLaser focusing: Focusing

Implementation Method 4

maintaining structural integrity and allowing for stealth dicing using the same laser

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS8809165B2Method for fusing a laser fuse and method for processing a wafer

Publication Date: 2014.08.19 INFINEON TECHNOLOGIES AG

AI summary

A method for fusing a laser fuse in accordance with various embodiments may include: providing a semiconductor workpiece having a substrate region and at least one laser fuse; fusing the at least one laser fuse from a back side of the substrate region by means of an infrared laser beam.