Selective ILD Protection During Metal Cut Etching
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Solution Overview
Problem
During semiconductor device assembly, the removal of metal liners and fillers in trench regions often results in significant loss of interlayer dielectric (ILD) material, leading to recessed ILD regions that block etching paths for source-drain interconnects, hindering the creation of effective source-drain contacts.
Innovation Solution
A method involving selective deposition of protective layers, such as high-k dielectric materials or self-assembled monolayers, on the ILD or high-k dielectric surfaces to prevent erosion during metal liner etching, allowing for the preservation of ILD layers and enabling etching through to create source-drain interconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If metal liner removal is performed to create trench regions, then the trench region is formed for gate structure, but significant ILD material loss occurs causing recessed ILD regions that block etching paths
Solution Approach 1:
A protective layer is deposited on the ILD layer before metal liner removal to prevent ILD material loss during the etching process. This preliminary protective action ensures that when the metal liner is subsequently removed to form the trench region, the ILD layer remains intact and does not become recessed, maintaining open etching paths for source-drain interconnects.
Solution Approach 2:
The protective layer acts as an intermediary between the etching process and the ILD layer. This intermediate layer is selectively removed after metal liner removal, having served its protective function. The protective layer mediates the harmful effect of etching on the ILD while allowing the desired trench formation to occur.
2Loss of substance
If protective layer is deposited on ILD layer to prevent erosion, then ILD layer loss is minimized, but process complexity increases due to additional deposition and removal steps
Solution Approach 1:
The protective layer is designed with specific material properties that enable selective deposition and selective removal. By changing the material parameters (choosing appropriate protective layer materials with distinct etching characteristics), the process achieves protection during metal liner removal while allowing clean subsequent removal of the protective layer without affecting the ILD layer.
Solution Approach 2:
The protective layer is treated as a temporary, disposable element in the process. It is deposited to perform its protective function during a specific process window, then removed when no longer needed. This approach accepts the added process steps as a trade-off for the critical function of preventing ILD loss, viewing the protective layer as a consumable protective measure.
3Ease of operation
If metal liner and metallic filler are removed from trench region, then source-drain interconnect etching is enabled, but ILD recession blocks the etching path
Solution Approach 1:
The protective layer is deposited on the ILD layer before the metal liner and metallic filler removal process. This preliminary protective measure ensures that when the trench region is cleared of metal materials to enable source-drain interconnect etching, the ILD layer remains at its original level without recession, maintaining open etching paths to the substrate.
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 effectively minimizes ILD layer loss and prevents blockage by the cut liner filler, allowing for successful etching through the ILD layer to establish source-drain interconnects without significant ILD recession, thus ensuring the integrity of the semiconductor structure.
Implementation Method 1
depositing a protective layer selective to the interlayer dielectric layer so that the protective layer is formed onto a top portion associated with the interlayer dielectric layer
Implementation Method 2
depositing a self-assembled monolayer onto the top portion
Implementation Method 3
removing the metal liner
Data Source
AI summary
The present disclosure relates to methods and apparatuses related to the deposition of a protective layer selective to an interlayer dielectric layer so that the protective layer is formed onto a top portion associated with the interlayer dielectric layer. In some embodiments, a method comprises: forming an interlayer dielectric layer on a substrate; covering a trench region with a metal liner, wherein the trench region is situated above the substrate and formed within the interlayer dielectric layer; and depositing a protective layer selective to the interlayer dielectric layer so that the protective layer is formed onto a top portion associated with the interlayer dielectric layer. In various embodiments, the depositing the protective layer comprises: repeatedly depositing the protective layer via a multi-deposition sequence; or depositing a self-assembled monolayer onto the top portion.