Electrodeposited Flip-Chip Bases Surface Cleaning via RTP and Etching

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Solution Overview

Problem

Electrodeposited bases with external contacts for flipchip contacts face reliability issues due to contaminants and surface roughness, which degrade surface mounting reliability, unlike soldered globules.

Innovation Solution

A method involving electrodeposition of bases with external contacts on semiconductor wafers or chips, followed by heat treatment below the melting temperature, a rapid temperature process (RTP) to reach the melting temperature, and subsequent wet etching to clean and smooth the surfaces, effectively removing contaminants and improving surface mounting reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electrodeposition is used to produce bases with external contacts, then productivity is improved by enabling batch processing of multiple wafers, but reliability deteriorates due to contaminants and surface roughness

Engineering Contradiction:

Improvebatch processing efficiencyVSAvoidsurface mounting reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary heat treatment and RTP processes to electrodeposited bases before surface mounting. The heat treatment removes volatile contaminants and performs stress relief, while RTP eliminates surface oxides and prepares the surface for reliable bonding, thereby resolving the reliability issues inherent in electrodeposition while maintaining batch processing productivity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical and chemical parameters of the electrodeposited base through controlled heat treatment (temperature, time, atmosphere) and RTP processing. These parameter changes transform the surface properties to achieve reliable surface mounting while preserving the productivity benefits of electrodeposition

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If wet etching is applied to electrodeposited bases, then surface roughness increases creating a jagged surface, but this is attempted to improve wettability

Engineering Contradiction:

Improvesurface wettabilityVSAvoidsurface smoothness

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent converts the harmful surface roughness created by wet etching into a beneficial feature by subsequently applying heat treatment and RTP processes. These processes smooth the jagged surface while maintaining the wettability improvements, thereby transforming the harmful roughness into acceptable surface characteristics for reliable mounting

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If soldering globules are used for flipchip contacts, then reliability is maintained through simple melting process, but productivity deteriorates due to time-consuming individual placement

Engineering Contradiction:

Improvesurface mounting reliabilityVSAvoidmounting process speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces the mechanical process of individual soldering globule placement with an electrochemical deposition process.电极position enables batch processing of multiple contacts simultaneously through electrochemical reactions, achieving both high productivity and reliable surface mounting when combined with the subsequent heat treatment and RTP processes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances the reliability of surface mounting by eliminating jaggedness and surface roughness, ensuring consistent contact and reducing the time-consuming process of aligning soldering globules, while allowing for efficient production of multiple bases with external contacts.

Implementation Method 1

bases with external contacts are electrodeposited on contact surfaces of semiconductor wafers or semiconductor chips

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Implementation Method 2

heat treatment of electrodeposited bases with external contacts of the semiconductor wafers or the semiconductor chips at temperatures below the melting temperature

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 3

traversing an RTP high-temperature interval in the case of which at least the melting temperature is reached

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 4

wet etching the surfaces of the bases with external contacts

Methodology Applied

Scientific EffectWet etching:

Data Source

PatentUS7723158B2Method for producing and cleaning surface-mountable bases with external contacts

Publication Date: 2010.05.25 INFINEON TECHNOLOGIES AG

AI summary

In a method for producing bases with external contacts for surface mounting on circuit mounts, bases with external contacts are electrodeposited on semiconductor wafers or semiconductor chips. Subsequently, electrodeposited bases with external contacts are heat treated on the semiconductor wafers or the semiconductor chips at temperatures below the melting temperature of the deposited contact base material. Thereafter, a so-called RTP process is carried out in the form of a high-temperature interval in which the melting temperature is reached. Subsequently, the surfaces of the bases with external contacts are wet etched, the overall method being terminated by a cooling and drying operation. The bases with external contacts thus produced can be reliably surface mounted on circuit mounts.