Copper Pad Smoothing Chambers for Micro-LED Bonding

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Solution Overview

Problem

Current methods for transferring and bonding micro-LED elements to display backplanes face challenges due to the difficulty in achieving high smoothness of copper contact pads, as commercial copper chemical-mechanical planarization and electropolishing tools are not adapted for large substrates or discrete contact pads, leading to inadequate surface roughness for effective bonding.

Innovation Solution

A semiconductor manufacturing apparatus with discrete open chambers is used to smooth copper surfaces on large substrates, employing reactive plasma or ionic gases to form volatile compounds that are then vaporized and removed, followed by purging, to achieve atomic-level smoothness of copper contact pads, enabling effective bonding between micro-LED elements and the display backplane.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If commercial copper chemical-mechanical planarization and electropolishing tools are used, then copper surface smoothness is improved, but these tools are not adapted for large substrates or discrete contact pads

Engineering Contradiction:

Improvecopper surface smoothnessVSAvoidadaptability to large substrates and discrete contact pads

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent divides the substrate into discrete regions corresponding to individual contact pads. Each contact pad is treated independently through discrete open chambers that can be selectively positioned over specific pads, allowing customized smoothing for each discrete contact pad rather than treating the entire large substrate uniformly.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention applies smoothing processes locally to specific contact pad regions rather than uniformly across the entire substrate. The discrete open chambers enable selective application of reactive plasma or ionic gas treatments to individual contact pads, providing localized surface quality improvement where needed.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If reactive plasma or ionic gas is used to form volatile compounds on copper surface, then atomic-level smoothness is achieved, but additional steps for vaporization and purging are required

Engineering Contradiction:

Improvesurface roughness reduction to atomic-level smoothnessVSAvoidprocess steps including vaporization and purging

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into integrated chambers. The same discrete open chambers that deliver reactive plasma or ionic gas also serve as vaporization zones and purging environments. By controlling atmospheric conditions within these chambers, the system merges etching, vaporization, and purging operations into a unified process sequence, reducing overall system complexity despite the multi-step nature of the process.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The process operates through continuous sequential steps within the same chamber system. After reactive gas forms volatile compounds on the copper surface, the chamber atmosphere is continuously adjusted to enable vaporization, followed by purging. This continuous action within integrated chambers eliminates the need for separate equipment for each step, maintaining process efficiency.

Inventive Principle:

Principle #20Continuity of useful 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

The method achieves a significant reduction in surface roughness from 3-5 nm to less than 0.5 nm, facilitating strong and reliable bonding of micro-LEDs to the backplane, enhancing the yield and throughput of micro-LED display manufacturing.

Implementation Method 1

introduce a reactive plasma or ionic gas into a first chamber of a set of chambers of a smoothing tool

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 2

reactive plasma or ionic gases to form volatile compounds that are then vaporized and removed

Methodology Applied

Scientific EffectChemical reaction to form volatile compounds: Chemical Bonding

Implementation Method 3

a heating element coupled to the housing to supply heat to at least one of the chambers

Methodology Applied

Scientific EffectThermal heating: Heating

Implementation Method 4

volatile compounds that are then vaporized and removed

Methodology Applied

Scientific EffectVaporization: Evaporation

Data Source

PatentUS12119435B2Semiconductor smoothing apparatus and method

Publication Date: 2024.10.15 INTEL CORP

AI summary

An semiconductor manufacturing apparatus and method to smooth surfaces of discrete pads on a substrate. The method includes placing a surface of one of the discrete pads in registration with a first chamber of a set of chambers of a smoothing tool, the set corresponding to a smoothing cycle of the smoothing tool; etching, within the first chamber, a surface of one of the discrete pads to form an etch layer on the surface; placing the surface in registration with a second chamber of the set; after the etch, pumping gas and vapor from the surface within the second chamber; placing the surface in registration with a third chamber of the set; and applying heating to the surface in the third chamber to smooth the surface.