Plasma Mediated Ashing Protective Layer Formation
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Solution Overview
Problem
Current plasma mediated ashing processes cause significant substrate material loss and oxidation, particularly during photoresist removal in advanced semiconductor manufacturing, which is undesirable for 32 nm and beyond technology nodes where minimal silicon loss is required.
Innovation Solution
A process involving the formation of a protective layer on the substrate using nitrogen or carbon containing gases and ultraviolet radiation before and/or during plasma mediated photoresist stripping, allowing for controlled removal of organic material while minimizing substrate damage, using a plasma processing system with a gas delivery and power generator assembly to manage the plasma environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma mediated ashing processes are used to remove photoresist, then photoresist removal is achieved, but significant substrate material loss and oxidation occur
Solution Approach 1:
A protective layer is formed on the substrate surface before the plasma ashing process begins. This preliminary protective layer prevents direct interaction between the plasma and substrate, thereby preventing substrate oxidation and material loss while allowing efficient photoresist removal during the subsequent ashing process.
Solution Approach 2:
The protective layer acts as an intermediary between the plasma and the substrate. It mediates the interaction by absorbing the harmful effects of plasma on the substrate while still permitting the plasma to effectively remove the photoresist organic material, thus resolving the contradiction between removal efficiency and substrate protection.
2Productivity
If conventional plasma mediated ashing processes are used to remove photoresist, then photoresist removal is achieved, but substrate oxidation occurs
Solution Approach 1:
The protective layer is deposited beforehand to create a barrier that prevents oxygen from the plasma from reaching and oxidizing the substrate. This preliminary protective measure allows the ashing process to proceed with high productivity without the harmful side effect of substrate oxidation.
Solution Approach 2:
The protective layer converts the potentially harmful oxidizing plasma into a beneficial process by filtering out the harmful oxygen species while allowing the plasma to maintain its effectiveness in removing organic photoresist material. The plasma's energy is redirected to photoresist removal rather than substrate oxidation.
3Productivity
If aggressive chemistries are used to remove hardened photoresist crust, then photoresist removal efficiency is improved, but substrate damage increases
Solution Approach 1:
The protective layer serves as an intermediary shield that enables the use of more aggressive plasma chemistries for photoresist removal. It absorbs the harsh effects of aggressive chemistries that would otherwise damage the substrate, while still permitting efficient photoresist and crust removal during the ashing 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
This approach significantly reduces substrate material loss and oxidation, achieving near-zero silicon loss and maintaining the integrity of sensitive substrate materials like silicon and SiGe, aligning with the stringent requirements of advanced semiconductor technology.
Implementation Method 1
The ashing process generally occurs after an etching or implant process has been performed in which a photoresist material is used as a mask for etching a pattern into the underlying substrate
Implementation Method 2
The substrate damage may be in the form of substrate erosion (e.g., etching, sputtering, physical removal of a portion of the substrate)
Data Source
AI summary
A method for processing a substrate includes arranging a substrate including masked portions and unmasked portions in a process chamber; creating plasma in a process chamber; supplying a passivation gas mixture that includes nitrogen or carbon to create a plasma passivation gas mixture; exposing a substrate to the plasma passivation gas mixture to create a passivation layer on the unmasked portions of the substrate; supplying a stripping gas mixture that includes oxygen to the plasma to create a plasma stripping gas mixture; exposing the substrate to the plasma stripping gas mixture to strip at least part of the masked portions and at least part of the unmasked portions; and repeating creating the passivation layer and the stripping to remove a predetermined amount of the masked portions.