Selective Hard Mask Etching for Low-k and Copper Preservation
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Solution Overview
Problem
Existing compositions fail to effectively and precisely remove post-etch residues and etch hard masks comprising aluminum compounds while preserving low-k materials, copper, and tungsten in semiconductor manufacturing, especially for sub-7 nm structures.
Innovation Solution
A cleaning composition comprising solubilizers, corrosion inhibitors, polar organic solvents, and oxidants is used to selectively etch or partially etch layers of Ti, TiN, Ta, TaN, Al, and HfOx, as well as tungsten carbide and tungsten nitride, without significantly compromising low-k materials, copper, or cobalt, suitable for a one-step process in semiconductor manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing compositions are used to remove post-etch residues and etch hard masks, then etching capability is achieved, but low-k materials, copper, and tungsten are damaged or compromised
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating specific corrosion inhibitors (benzotriazole and its derivatives) and chelating agents (EDTA, DTPA) alongside oxidants. This parameter change enables selective etching of aluminum-containing hard masks while the corrosion inhibitors protect copper and tungsten from oxidation damage, and chelating agents prevent metal ion precipitation that could damage low-k materials.
Solution Approach 2:
The patent introduces corrosion inhibitors as intermediary substances that mediate between the oxidant (which provides etching capability) and the sensitive materials (copper, tungsten, low-k materials). The benzotriazole derivatives act as protective intermediaries that preferentially bind to copper and tungsten surfaces, preventing direct contact with oxidizing agents while allowing aluminum etching to proceed.
2Productivity
If a one-step process is used for removing residues and etching hard masks, then productivity is improved, but manufacturing precision and selectivity are compromised
Solution Approach 1:
The patent creates a universal cleaning composition that performs multiple functions simultaneously: removing organic residues, etching aluminum-containing hard masks, and protecting sensitive materials. This multi-functional formulation achieves both high productivity (one-step process) and high manufacturing precision (selective etching) by combining solubilizers, corrosion inhibitors, chelating agents, and oxidants in specific concentrations.
Solution Approach 2:
The patent employs a composite chemical formulation containing multiple active ingredients with complementary functions: oxidants (H2O2, peracetic acid) for etching, benzotriazole derivatives for copper/tungsten protection, EDTA/DTPA for chelation, and solubilizers (ammonium hydroxide, isopropanol). This composite approach enables selective etching in a single step while maintaining precision through the synergistic interaction of components.
3Speed
If strong oxidants are used to etch hard masks effectively, then etching speed is improved, but copper and tungsten layers are oxidized and damaged
Solution Approach 1:
The patent applies preliminary anti-action by incorporating corrosion inhibitors (benzotriazole and its derivatives) that preemptively protect copper and tungsten surfaces from oxidation before the oxidant can attack these materials. These inhibitors form protective films on copper and tungsten surfaces, creating a barrier that prevents harmful oxidation while allowing the oxidant to continue etching aluminum-containing hard masks.
Solution Approach 2:
The patent carefully controls the concentration and type of oxidant (using H2O2 at 3-25% or peracetic acid at 0.1-10%) and balances it with corrosion inhibitor concentrations (0.1-10% benzotriazole derivatives). This parameter optimization enables sufficiently fast etching speeds while the corrosion inhibitors neutralize the harmful oxidative effect on copper and tungsten, achieving both speed and protection.
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 composition achieves controlled and specific etching of hard masks and etch-stop layers, preserving underlying materials, enabling the production of 7 nm and sub-7 nm structures with minimal damage to low-k materials, copper, and tungsten.
Implementation Method 1
the use of a cleaning composition in combination with one or more oxidants for removing post-etch or post-ash residue from the surface of a semiconductor substrate
Implementation Method 2
for oxidative etching or partially oxidative etching of a layer or mask comprising or consisting of a material selected from the group consisting of TiN, Ta, TaN, Al and HfOx
Implementation Method 3
comprising (i) as solubilizer one or more compounds of formula I
Implementation Method 4
(ii) one or more corrosion inhibitors
Implementation Method 5
(iii) one or more polar, non-protogenic organic solvents
Data Source
AI summary
Described herein is a method of using a cleaning composition in combination with one or more oxidants for removing post-etch or post-ash residue from the surface of a semiconductor substrate and/or for oxidative etching or partially oxidative etching of a layer or mask. Also described herein is the cleaning composition and a method of using the cleaning composition for removing post-etch or post-ash residue from the surface of a semiconductor substrate. Also described herein is a wet-etch composition including the cleaning composition and one or more oxidants as well as a method of using the wet-etch composition. Also described herein are a process for the manufacture of a semiconductor device from a semiconductor substrate and a kit including the cleaning composition and one or more oxidants.