Selective Conductive Cap Deposition for Fully-Aligned-Via Etch Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In semiconductor device fabrication, the formation of fully-aligned-via features is hindered by the difficulty in achieving exact etch depth, leading to damage and contamination of conductive elements and the processing chamber, which degrades wafer yield and causes process shifts.
Innovation Solution
A method and system for selective deposition of a conductive cap using a plasma etch process that forms a conformal etch stop layer and selectively etches it using non-corrosive chemistry, preventing damage to underlying conductive layers and minimizing contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rough deposition processes or CVD processes are used to deposit conductive material for vias, then the conductive material can be deposited, but the underlying conductive elements may be damaged and contamination may occur
Solution Approach 1:
A conductive cap layer is deposited over the conductive elements before via formation. This cap layer serves as an intermediary protective barrier during the etch process, preventing direct exposure and damage to the underlying conductive elements. The cap is selectively removed after the via etch is complete, allowing the conductive elements to remain protected while enabling via formation.
Solution Approach 2:
The conductive cap is deposited in advance before the via etch process begins. This preliminary protective layer is formed conformally over the conductive elements and etch stop layer, ensuring that the conductive elements are protected from potential damage and contamination during the subsequent etching operations.
2Productivity
If etch depth is not precisely controlled, then the via formation process can proceed, but the underlying device layer and conductive elements may be damaged
Solution Approach 1:
The conductive cap layer acts as a sacrificial protective barrier that can be selectively removed. During the via etch process, even if the etch depth exceeds the intended target, the conductive cap prevents damage to the underlying conductive elements. The cap is selectively removed in a subsequent step, allowing precise via formation without compromising the integrity of the conductive elements.
Solution Approach 2:
The conformal conductive cap layer provides a cushioning protective layer before the via etch process. This pre-deposited cap absorbs any excess etch depth, preventing the etch from reaching and damaging the underlying conductive elements. The cap is designed to be selectively removable, allowing precise control of the final via depth while protecting against over-etching damage.
3Ease of manufacture
If etch stop layer material residue remains, then the etch process can be simplified, but the workpiece and chamber may be contaminated
Solution Approach 1:
The conductive cap layer serves as an intermediary barrier between the etch stop layer and the via etch process. By depositing the conductive cap conformally over the etch stop layer, the cap prevents direct contact between the etch chemistry and the etch stop layer material, thereby preventing contamination and residue formation in the chamber while maintaining process simplicity.
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 solution effectively protects the underlying conductive layers and maintains high selectivity, reducing contamination and improving wafer yield by using a conductive cap material like ruthenium, which is highly selective to common etch stop layer materials, thus maintaining precise dimensions and reducing chamber contamination.
Implementation Method 1
selectively etching the etch stop layer using a plasma etch process, wherein the plasma etch process removes the etch stop layer selective to the second conductive material comprising the cap
Implementation Method 2
forming a conformal etch stop layer in contact with a surface of the cap and in contact with a region of the ILD layer
Data Source
AI summary
Methods and systems for selective deposition of conductive a cap for FAV features are described. In an embodiment, a method may include receiving a substrate having an interlayer dielectrics (ILD) layer, the ILD layer having a recess, the recess having a conductive layer formed therein, the conductive layer comprising a first conductive material. Additionally, such a method may include forming a cap within a region defined by the recess and in contact with a surface of the conductive layer, the cap comprising a second conductive material. The method may also include forming a conformal etch stop layer in contact with a surface of the cap and in contact with a region of the ILD layer. Further, the method may include selectively etching the etch stop layer using a plasma etch process, wherein the plasma etch process removes the etch stop layer selective to the second conductive material comprising the cap.