Chiplet Adhesion via Localized Surface Conditioning
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Solution Overview
Problem
The challenge in manufacturing OLED display devices is the variability and misalignment of thin-film transistors (TFTs) on substrates, leading to inconsistent luminance and visual quality, which is exacerbated by the complexity and cost of compensation schemes and the difficulty in accurately placing chiplets on substrates due to contamination and improper preparation.
Innovation Solution
A method is introduced to correct missing or misaligned chiplets on a substrate by coating an adhesive layer, placing first chiplets, locally processing the adhesive in non-adhered areas to condition it for second chiplets, and curing the adhesive to ensure proper alignment and adhesion, using techniques such as laser ablation, micro gas jets, and additional adhesive dispensing to remove contaminants and misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chiplets are placed on substrate using conventional methods, then manufacturing process is simple, but chiplet alignment precision and adhesion reliability are insufficient due to contamination and misalignment
Solution Approach 1:
The substrate surface is pre-treated with plasma or chemical cleaning methods before chiplet placement to remove organic contaminants and create a clean, reactive surface. This preliminary action ensures optimal adhesion conditions are established before the chiplets are applied, preventing misalignment and adhesion failures that would require rework.
Solution Approach 2:
A specialized adhesive layer with controlled viscosity and curing characteristics is introduced as an intermediary between the substrate and chiplets. This adhesive layer compensates for minor surface irregularities and provides a reliable bonding interface, while alignment marks and positioning fixtures serve as intermediaries to ensure precise chiplet placement.
2Reliability
If additional compensation schemes are added to TFT circuits, then TFT variability is compensated, but device complexity and manufacturing cost increase
Solution Approach 1:
The compensation function is extracted from the TFT circuit itself and transferred to the chiplet level. By placing precisely engineered chiplets with compensation circuitry closer to the OLED pixels, the variability compensation is achieved without adding complexity to the main TFT driving circuits, thereby maintaining luminance consistency while avoiding increased device complexity.
3Reliability
If substrate preparation is thorough to avoid contamination, then chiplet adhesion is reliable, but manufacturing time and cost increase
Solution Approach 1:
The substrate surface treatment process is designed as a continuous plasma cleaning operation that treats the entire substrate surface without interruption. This continuous action ensures uniform contamination removal across the substrate, achieving reliable adhesion throughout while maintaining high manufacturing throughput without requiring multiple discrete cleaning steps.
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 improves yield by ensuring accurate placement and alignment of chiplets, enhancing the visual quality and reliability of OLED displays by addressing the issues of chiplet misalignment and contamination, thereby reducing manufacturing complexity and cost.
Implementation Method 1
using techniques such as laser ablation, micro gas jets, and additional adhesive dispensing to remove contaminants and misalignments
Implementation Method 2
curing the adhesive to ensure proper alignment and adhesion
Data Source
AI summary
A method of providing chiplets over a substrate including providing in sequence a substrate; coating an adhesive in a layer over the substrate; placing a plurality of first chiplets onto the adhesive layer in separated chiplet location(s) to adhere the first chiplets to the adhesive layer, wherein one or more of the first chiplets do not adhere to the adhesive layer, so that first chiplet(s) are adhered to the adhesive layer in adhered chiplet location(s) and first chiplet(s) are not adhered in non-adhered chiplet location(s); locally processing the adhesive layer in the non-adhered chiplet location(s) to condition the adhesive layer in the non-adhered locations to receive second chiplets; placing second chiplet(s) onto the adhesive layer in the conditioned non-adhered chiplet location(s) to adhere the second chiplets in the adhesive layer in the non-adhered locations; and curing the adhesive.