Multi-Layer Etch Stop Structure for Corrosion-Safe Via Etching
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Solution Overview
Problem
Conventional fabrication processes face challenges in scaling integrated circuits to the 10 nanometer node and sub-10 nanometer node range due to variability and constraints on semiconductor processes, particularly in multi-gate transistors and back-end-of-line metallization layers, leading to issues like punch-through and corrosion of underlying metals.
Innovation Solution
The implementation of a multi-layer etch stop layer using wet-strip removable aluminum oxide layers provides enhanced dry etch selectivity in both front-end-of-line and back-end-of-line manufacturing, ensuring precise etching of vias and trenches without attacking underlying copper or cobalt, thereby mitigating punch-through and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used for scaling integrated circuits to 10 nanometer node and smaller, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to variability and constraints on semiconductor processes
Solution Approach 1:
The etch stop layer is divided into multiple distinct layers (first etch stop layer, second etch stop layer, third etch stop layer) with different materials and etch selectivities. This segmentation allows each layer to be optimized for specific etching operations, achieving high manufacturing precision for different structures without requiring a complete process overhaul
Solution Approach 2:
The multi-layer etch stop structure acts as an intermediary between the etching process and the underlying metal layers. The specific etch stop layers (such as the aluminum oxide layer) provide a controlled interface that prevents direct interaction between etchants and sensitive metal interconnects, thereby protecting against corrosion while maintaining etching precision
2Reliability
If multi-gate transistors are fabricated on bulk silicon substrates to reduce cost, then ease of manufacture is improved, but reliability deteriorates due to punch-through and corrosion issues
Solution Approach 1:
The etch stop layers are deposited beforehand to create a protective cushion between subsequent processing steps and the underlying metal interconnects. This pre-established barrier prevents punch-through and corrosion during later etching operations, ensuring device reliability without adding significant fabrication complexity
Solution Approach 2:
The etch stop structure uses composite materials including aluminum oxide, silicon nitride, and other dielectric materials with different etch selectivities. This composite approach provides both protection against metal corrosion and compatibility with bulk silicon substrate fabrication processes, balancing reliability and ease of manufacture
3Manufacturing precision
If dry etching is performed to create vias and trenches, then manufacturing precision is improved, but object-generated harmful factors worsen due to punch-through and corrosion of underlying metals
Solution Approach 1:
The etch stop layers serve as an intermediary barrier between the dry etching process and the underlying metal interconnects. Materials like aluminum oxide provide high etch selectivity, allowing precise via and trench formation while preventing etchant penetration to the metal layers, thus eliminating corrosion without sacrificing etching precision
Solution Approach 2:
The patent utilizes materials with dramatically different etch selectivity parameters (greater than 10:1, preferably greater than 20:1 selectivity). This parameter difference allows the etching process to precisely define vias and trenches through the dielectric layers while automatically stopping before reaching the metal interconnects, preventing harmful corrosion effects
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 improves yield and reliability by preventing copper or cobalt corrosion, maintaining depth uniformity, and enhancing the shorting margin, resulting in improved integrated circuit performance.
Implementation Method 1
provides enhanced dry etch selectivity in both front-end-of-line and back-end-of-line manufacturing, ensuring precise etching of vias and trenches without attacking underlying copper or cobalt
Data Source
AI summary
Multi-layer etch stop layers are described. In an example, an integrated circuit structure includes a conductive line in a first interlayer dielectric material above a substrate. A first dielectric etch stop layer, a second dielectric layer and a third dielectric layer are on the conductive line and the first interlayer dielectric material. A second interlayer dielectric material is on the third dielectric etch stop layer. An opening is in the second interlayer dielectric material, in the third dielectric etch stop layer, and in the second dielectric etch stop layer, in the first dielectric etch stop layer. A conductive structure is in the opening, the conductive structure in direct contact with the conductive line.