TiN Etching Uniformity via pH and Oxidizer Control
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Solution Overview
Problem
Existing etching methods for semiconductor substrates with TiN-containing layers face challenges in achieving consistent etching performance and uniformity due to variations in physical properties and atomic composition, particularly oxygen concentration, leading to inconsistent etching rates and quality.
Innovation Solution
An etching method using a liquid composition containing hydrogen peroxide as an oxidizing agent and an organic amine compound as a basic component, with a pH adjusted between 8.5 and 13, which effectively removes TiN-containing layers while maintaining in-plane uniformity and etching rate across substrates with different oxygen concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used on substrates with varying TiN-containing layers, then etching can be performed, but in-plane etching uniformity and etching rate become inconsistent due to different oxygen concentrations
Solution Approach 1:
The patent changes the chemical parameters of the etching liquid by incorporating hydrogen peroxide as an oxidizing agent and adjusting pH to 8.5-13 using organic amine compounds. This parameter modification enables the etching liquid to effectively remove TiOx layers formed on TiN-containing layers with different oxygen concentrations, achieving consistent etching performance across varied substrates
Solution Approach 2:
The patent introduces an intermediary mechanism where hydrogen peroxide oxidizes the TiN-containing layer to form TiOx, which is then removed by the etching liquid. This two-step process involving oxidation as an intermediary reaction enables uniform etching regardless of the initial oxygen concentration in the TiN layer
2Reliability
If etching conditions are optimized for one type of substrate, then good etching performance is achieved for that substrate, but etching performance varies when applied to substrates with different physical properties
Solution Approach 1:
The etching liquid composition is designed with universal applicability by using hydrogen peroxide oxidation combined with organic amine-based etching. This multi-functional approach can handle TiN-containing layers with varying oxygen concentrations, making it suitable for diverse substrate types including CMOS, DRAM, and other semiconductor devices without requiring condition optimization for each substrate type
3Productivity
If strong etching conditions are used to achieve high etching rate, then etching speed increases, but in-plane uniformity deteriorates
Solution Approach 1:
The patent optimizes the chemical parameters by controlling pH between 8.5-13 and using hydrogen peroxide concentration to achieve a balanced etching state. This parameter optimization enables the system to maintain high etching rates while preserving in-plane uniformity, avoiding the trade-off between speed and quality
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 ensures stable and uniform etching performance across substrates with varying TiN-containing layers, achieving high etching rates and quality without residue issues, even when substrates have different oxygen concentrations.
Implementation Method 1
hydrogen peroxide incorporated as an oxidizing agent
Implementation Method 2
wet etching which uses a chemical liquid
Implementation Method 3
effective removability of a TiN-containing layer
Data Source
Figure 1~2
AI summary
An etching method, having the step of applying an etching liquid onto a TiN-containing layer in a semiconductor substrate thereby etching the TiN-containing layer, the etching liquid comprising water, and a basic compound and an oxidizing agent in water thereof to be within the range of pH from 8.5 to 14, and the TiN-containing layer having a surface oxygen content from 0.1 mol% to 10 mol%.