MoOx Removal on Low-k Substrates Using Chlorine Soak and Remote Plasma
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Solution Overview
Problem
Current back-end-of-the-line (BEOL) packaging processes face challenges in removing molybdenum oxide (MoOx) from low-k dielectric materials without damaging them, as traditional methods are harsh and incompatible with these materials.
Innovation Solution
A chlorine-based soak process using molybdenum pentachloride (MoCl5) or tungsten pentachloride (WCl5) is employed at controlled temperatures and pressures, followed by a remote plasma treatment with hydrogen gas diluted with inert gases like argon or helium to remove MoOx and residual chlorine residues without damaging low-k materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional harsh precleaning processes are used to remove molybdenum oxide, then the MoOx is effectively removed, but the low-k dielectric materials are damaged
Solution Approach 1:
The patent changes the chemical parameters of the cleaning process by using chlorine-based chemistry (MoCl5 or WCl5) at controlled temperatures (350-460°C) and pressures (2-20 Torr), followed by plasma treatment with hydrogen diluted 1-99% with inert gas. These parameter changes enable effective MoOx removal while preventing damage to low-k materials that cannot withstand traditional harsh processes
Solution Approach 2:
The patent introduces a two-step process with an intermediary plasma treatment step between the chlorine-based soak and the final cleaning. The plasma treatment with diluted hydrogen acts as an intermediary that removes residual chlorine while protecting the low-k dielectric, mediating between the aggressive MoOx removal chemistry and the sensitive low-k material
2Reliability
If chlorine-based soak process is used to remove MoOx, then MoOx is effectively removed, but chlorine residue remains on the surface
Solution Approach 1:
The patent implements a continuous two-step process where the plasma treatment immediately follows the chlorine-based soak. The plasma treatment with hydrogen diluted in inert gas continuously acts on the surface to remove chlorine residues without interrupting the cleaning action, ensuring complete removal of harmful residues while maintaining the benefits of the chlorine-based MoOx removal
Solution Approach 2:
The patent converts the harmful chlorine residue into a beneficial intermediate state. The chlorine-based soak effectively removes MoOx, and the subsequent plasma treatment with hydrogen transforms and removes the chlorine residue. The process turns the potential harm of chlorine residue into a controlled intermediate step that is subsequently eliminated
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 effectively removes MoOx with no chlorine residue and minimal carbon loss or damage to low-k materials, ensuring compatibility with existing BEOL hydrogen gas preclean approaches and integration flows, while maintaining the integrity of low-k dielectric materials.
Implementation Method 1
performing a chlorine-based soak process to remove molybdenum oxide from the surface of the substrate
Implementation Method 2
performing a plasma treatment on the surface of the substrate with a remote plasma containing a hydrogen gas diluted with at least one inert gas to remove residual chlorine residue
Data Source
AI summary
Methods for cleaning oxides from a substrate surface are performed without affecting low-k dielectric or carbon materials on the substrate. In some embodiments, the method may include performing a preclean process with a chlorine-based soak to remove oxides from a surface of a substrate in a back end of the line (BEOL) process and treating the surface of the substrate with a remote plasma with a hydrogen gas and at least one inert gas to remove residual chlorine residue from the surface of the substrate without damaging low-k dielectric material or carbon material on the substrate.