Inkjet Printable Etch Resist for Semiconductor Current Tracks
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Solution Overview
Problem
The formation of current tracks on semiconductor devices is hindered by undercutting during etching, leading to irregular widths, non-uniform current flow, and electrical shorts, particularly on hydrophilic surfaces where conventional masking materials adhere poorly, and the challenge of working with smaller, more delicate materials.
Innovation Solution
A composition of solid hydrogenated rosin resin and liquid hydrogenated rosin resin ester, combined with fatty acids, is used as an inkjet printable etch resist, applied to semiconductor wafers to inhibit undercutting, ensuring uniform current tracks and improved adhesion on both hydrophilic and hydrophobic surfaces, allowing for finer line dimensions and reduced shadowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional masking materials are used for etching current tracks, then the etching process can be performed, but undercutting occurs leading to irregular widths and non-uniform current flow
Solution Approach 1:
The patent uses a composite resist material comprising a solid hydrogenated rosin resin and a liquid hydrogenated rosin resin ester in a weight ratio of 2:1 to 4:1. This composite formulation combines the adhesion benefits of solid resin with the flow and coverage properties of liquid resin, creating a mask that resists undercutting during etching while maintaining uniform current track dimensions and ensuring reliable electrical conductivity.
Solution Approach 2:
The patent modifies the chemical composition parameters of the resist material by using hydrogenated rosin resins instead of conventional masking materials. The specific weight ratio range (2:1 to 4:1) of solid to liquid resin components is optimized to achieve the desired balance between adhesion, etch resistance, and uniformity, preventing the undercutting phenomenon that plagues conventional approaches.
2Reliability
If conventional masking materials are used on hydrophilic surfaces, then masking can be applied, but adhesion is poor leading to increased undercutting
Solution Approach 1:
The composite resist system combines solid hydrogenated rosin resin with superior adhesion properties to hydrophilic surfaces with liquid hydrogenated rosin resin ester for improved flow and coverage. This synergistic combination ensures strong mask adhesion on hydrophilic semiconductor surfaces while maintaining precise current track width control during the etching process.
Solution Approach 2:
The hydrogenated rosin resin acts as an intermediary material that bridges the interface between the etchant and hydrophilic semiconductor surfaces. Its molecular structure provides both adhesion to the hydrophilic surface and resistance to the etchant, preventing undercutting while allowing precise definition of current track boundaries.
3Reliability
If thicker conductor tracks are used, then current conductivity is improved, but more surface area is shaded reducing light capture
Solution Approach 1:
The liquid hydrogenated rosin resin ester component of the composite resist provides hydraulic-like flow properties that enable the mask to conform precisely to the substrate surface and fill fine features. This allows the use of thinner conductor tracks with sufficient current conductivity, as the precise masking ensures uniform etching without undercutting, thereby reducing shadowing and improving light capture efficiency.
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 solution effectively reduces or eliminates undercutting, enabling uniform current flow, increased electrical output, and finer line dimensions, while maintaining sufficient adhesion to prevent capillary action and facilitating easy removal of the resist without residue, thus enhancing the efficiency and performance of semiconductor devices.
Implementation Method 1
The resists are of such a composition that they provide sufficient adhesion at an interface with the surface of the semiconductor itself or the surface of the antireflective layer to inhibit seepage of the etchant under the resist due to capillary action.
Implementation Method 2
applying an etch composition to the semiconductor to etch away exposed sections of the front side of the semiconductor to form current tracks
Implementation Method 3
provide sufficient adhesion at an interface with the surface of the semiconductor itself or the surface of the antireflective layer to inhibit seepage of the etchant under the resist due to capillary action
Data Source
AI summary
The methods involve selectively depositing a resist containing a solid hydrogenated rosin resin and a liquid hydrogenated rosin resin ester as a mixture on a semiconductor followed by etching uncoated portions of the semiconductor and simultaneously inhibiting undercutting of the resist. The etched portions may then be metallizaed to form current tracks.