TiN Etching Uniformity via Oxygen Content and Organic Additives
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing etching methods for semiconductor substrates, particularly those involving titanium nitride (TiN) layers, suffer from surface non-uniformity and residue issues due to the use of etching liquids with hydrofluoric acid and hydrogen peroxide, leading to etching unevenness and inadequate removal of hard masks.
Innovation Solution
An etching method using a substrate with a surface oxygen content of 0.1-10% mole, employing an etching liquid containing hydrofluoric acid, an oxidizing agent, and a surface uniformizing agent like nitrogen-containing organic compounds, which helps in achieving uniform etching of TiN and metal layers by controlling the etching rate and pH.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an etching liquid containing hydrofluoric acid and hydrogen peroxide is used, then the etching rate of TiN layer is improved, but the surface uniformity deteriorates causing etching unevenness and residues
Solution Approach 1:
The patent changes the chemical composition parameters of the etching liquid by adding specific organic compounds (carboxylic acids, alcohols, or ketones) to the existing hydrofluoric acid and hydrogen peroxide mixture. This parameter modification enables simultaneous achievement of high etching rate and surface uniformity by controlling the interaction between the organic additive and the TiN surface during etching
Solution Approach 2:
The organic compound acts as an intermediary substance that mediates between the aggressive etching agents (HF and H2O2) and the TiN surface. It facilitates uniform etching by controlling the etching reaction at the surface, preventing the formation of residues while maintaining high etching efficiency
2Productivity
If conventional etching liquids are used to remove TiN hard mask, then the removal efficiency is improved, but the metal layer surface uniformity deteriorates
Solution Approach 1:
The patent modifies the etching liquid composition by incorporating organic compounds that selectively interact with TiN while being less aggressive toward metal layers. This parameter change enables efficient TiN removal while preserving the uniformity of the underlying metal layer surface
Solution Approach 2:
The etching liquid exhibits local quality by having different etching effects on different materials: it aggressively removes TiN where needed while being gentler on metal layers. The organic additive creates this selective local effect by preferentially reacting with or protecting specific materials during the etching process
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 uniformization of both TiN and metal surfaces, reducing etching unevenness and enabling efficient removal of TiN layers while maintaining the integrity of the metal layers, thereby improving semiconductor device production quality.
Implementation Method 1
applying an etching liquid containing a hydrofluoric acid compound and an oxidizing agent to the substrate and thereby removing the first layer
Implementation Method 2
applying an etching liquid containing a hydrofluoric acid compound and an oxidizing agent to the substrate and thereby removing the first layer
Data Source
AI summary
An etching method containing, at the time of processing a substrate having a first layer containing titanium nitride (TiN) and a second layer containing a transition metal, selecting a substrate in which a surface oxygen content of the first layer is from 0.1 to 10% by mole, and applying an etching liquid containing a hydrofluoric acid compound and an oxidizing agent to the substrate and thereby removing the first layer.