Titanium Seed Layer Etching With UV for Low-Undercut Structuring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor and IC substrate structuring methods using wet chemical etching face challenges in achieving resolutions below 2 μm due to undercuts and hazardous process conditions, particularly with the use of titanium seed layers etched by hydrofluoric acid or alkaline solutions.
Innovation Solution
A method involving a titanium seed layer with a thickness of 100 to 300 nm, etched using phosphoric acid and UV light, which reduces undercuts and minimizes hazardous conditions by generating oxygen or ozone, allowing for smaller track widths and distances, and includes additional oxidizing agents and high-pressure rinsing for improved process control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydrofluoric acid or alkaline solutions are used to etch titanium seed layers, then titanium etching is achieved, but hazardous process conditions and explosion risks are created
Solution Approach 1:
The patent changes the chemical parameters of the etching process by using phosphoric acid instead of hydrofluoric acid or alkaline solutions. This substitution fundamentally alters the etching chemistry to eliminate hazardous conditions while maintaining effective titanium removal capability
Solution Approach 2:
The patent converts the typically problematic interaction between phosphoric acid and titanium into a beneficial process by utilizing controlled oxygen evolution and UV irradiation to achieve safe, selective etching with minimal undercut formation
2Manufacturing precision
If conventional wet chemical etching is used for titanium seed layers, then etching is achieved, but undercuts are formed which prevent resolution below 2 μm
Solution Approach 1:
The patent employs periodic action through UV irradiation during the etching process, which continuously generates oxygen to maintain controlled etching conditions and prevent undercut formation, enabling sub-2 μm resolution
Solution Approach 2:
By changing the etching chemistry to phosphoric acid and controlling oxygen availability through UV irradiation, the patent achieves isotropic etching with minimal undercut, enabling manufacturing precision below 2 μm resolution
3Manufacturing precision
If phosphoric acid is used to etch titanium with UV light exposure, then structure resolution below 2 μm is achieved, but process complexity increases
Solution Approach 1:
The patent merges the etching process with UV irradiation in a single integrated step, where UV light simultaneously drives oxygen evolution and activates the phosphoric acid etching, simplifying the overall process despite the advanced chemistry involved
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 enables the achievement of structural resolutions below 2 μm with reduced undercuts and safer process conditions, enhancing the control and reliability of substrate structuring while minimizing environmental and personnel risks.
Implementation Method 1
etching the titanium seed layer in the areas previously covered by the structured photoresist, wherein phosphoric acid is used to etch the titanium seed layer and, in addition, exposure to UV light is carried out during the etching of the titanium
Implementation Method 2
exposure to UV light is carried out during the etching of the titanium... generating oxygen or ozone
Implementation Method 3
phosphoric acid is used to etch the titanium seed layer
Implementation Method 4
In addition to the highly corrosive effect... there is also a risk of explosion through sudden decomposition of individual reaction components
Data Source
AI summary
A method for structuring a substrate is specified, in particular structuring by means of selective etching in the semiconductor and IC substrate industry, in which the following steps are carried out: providing a substrate, applying a titanium seed layer, full-area coating with a photoresist layer, lithographic structuring of the photoresist layer, in order to expose regions of the titanium seed layer, selectively depositing copper as conductor tracks in those areas in which the titanium seed layer is exposed, removing the structured photoresist, and etching the titanium seed layer in the areas previously covered by the structured photoresist, wherein phosphoric acid is used to etch the titanium seed layer and, in addition, exposure to UV light is carried out during the etching of the titanium.