Pre-Etch Carbon Deposition for Selective Metal Plasma Etching
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Solution Overview
Problem
The semiconductor industry faces challenges in selectively etching metal layers while protecting dielectric materials during plasma processing, particularly in complex 3D structures and high-volume IC manufacturing.
Innovation Solution
A method involving a pre-etch plasma pretreatment step that forms carbonaceous deposits over both dielectric and metal layers, followed by a halogen-containing plasma etch step that selectively etches the metal layers while the carbonaceous deposits protect the dielectric materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a halogen-containing plasma is used to etch metal layers, then the etching speed and efficiency are improved, but the dielectric materials are also etched causing damage and loss of selectivity
Solution Approach 1:
A carbon-containing plasma is applied before the halogen-containing plasma etch to deposit a carbonaceous layer on the dielectric material surface. This preliminary carbon deposition creates a protective barrier that prevents the halogen plasma from etching the dielectric, thereby enabling selective metal etching without damaging the underlying dielectric structures
Solution Approach 2:
The carbonaceous deposit formed by the carbon-containing plasma acts as an intermediary protective layer between the halogen-containing plasma and the dielectric material. This intermediate carbon layer selectively protects the dielectric from etching while allowing the halogen plasma to effectively etch the metal layers
2Manufacturing precision
If the etching process is made more selective to protect dielectric materials, then the manufacturing precision is improved, but the overall etching efficiency and productivity decrease
Solution Approach 1:
The carbon-containing plasma treatment is performed as a preliminary step before the main halogen plasma etch. This preliminary carbon deposition is quick and forms a thin protective layer that enables the subsequent high-efficiency halogen plasma etching to proceed without damaging the dielectric, thus maintaining both selectivity and productivity
Solution Approach 2:
The process utilizes different plasma parameters (carbon-containing gas composition, power levels, pressure, exposure time) to optimize the carbon deposition rate and layer quality. By carefully controlling these parameters, the carbonaceous protective layer is formed rapidly and efficiently, minimizing the impact on overall process productivity while ensuring adequate protection during the selective etch
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 enables selective etching of metal layers with high precision and accuracy, preventing damage to dielectric materials and improving the efficiency and selectivity of the etching process.
Implementation Method 1
exposing a substrate to a first plasma generated from a pretreatment gas including carbon, the first plasma forming a first carbonaceous deposit over the first layer and a second carbonaceous deposit over the second layer
Implementation Method 2
exposing the first carbonaceous deposit and the second carbonaceous deposit to a second plasma generated from an etch gas including halogen, the second plasma selectively etching the second carbonaceous deposit relative to the first carbonaceous deposit
Data Source
AI summary
A method of processing a substrate that includes: exposing a substrate to a first plasma including carbon, the substrate including a first layer including a dielectric material and a second layer including a metal, the first plasma forming a first carbonaceous deposit over the first layer and a second carbonaceous deposit over the second layer; exposing the first carbonaceous deposit and the second carbonaceous deposit to a second plasma including halogen, the second plasma selectively etching the second carbonaceous deposit relative to the first carbonaceous deposit to expose a surface of the second layer; and exposing the first carbonaceous deposit and the exposed surface of the second layer to the second plasma to selectively etch the second layer relative to the first carbonaceous deposit, the first carbonaceous deposit protecting the first layer from being etched by the second plasma.