Low-k Gate Spacer Layout for Overlay-Tolerant Semiconductor Contacts
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in scaling down device sizes due to difficulties in controlling critical dimension uniformity and overlay shift defects in photolithography, leading to increased parasitic capacitance and contact resistance, especially in advanced technology nodes below 20 nm.
Innovation Solution
A semiconductor structure is developed with a low-k spacer laterally contacting the gate structure's sidewall, which reduces parasitic capacitance and enlarges the overlay shift budget, using a low-k material like SiOCN with a dielectric constant between 2 and 3, and an etch stop layer to prevent electrical shorts and improve contact reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency increases and costs decrease, but critical dimension uniformity becomes more difficult to control and overlay shift defects increase
Solution Approach 1:
The patent applies preliminary action by forming a low-k spacer material around the gate structure sidewalls before the photolithography step that defines the contact holes. This pre-formed spacer structure serves as a physical reference that compensates for overlay shifts occurring during subsequent processing steps, thereby maintaining manufacturing precision even as feature sizes decrease to improve productivity
Solution Approach 2:
The patent changes the dielectric constant parameter by introducing low-k spacer material (with dielectric constant k < 3.5, preferably k < 2.5) around the gate structure. This parameter change reduces parasitic capacitance between the gate and contact holes, which becomes increasingly significant as feature sizes shrink. The low-k material property change enables continued scaling while maintaining electrical performance
2Area of stationary object
If device sizes are scaled down to increase functional density, then chip area utilization improves, but parasitic capacitance and contact resistance increase
Solution Approach 1:
The patent changes the dielectric parameter by introducing low-k spacer material with dielectric constant k < 3.5 (preferably k < 2.5) around the gate structure sidewalls. This parameter change directly reduces the parasitic capacitance between the gate and contact holes, which would otherwise increase as device sizes are scaled down to improve chip area utilization
Solution Approach 2:
The low-k spacer material acts as an intermediary dielectric layer between the gate structure and the contact holes. This intermediary material with low dielectric constant properties reduces the electric field coupling and parasitic capacitance that would otherwise be generated by the close proximity of conductive structures in scaled-down devices
3Device complexity
If photolithography overlay shift occurs due to decreasing feature sizes, then manufacturing complexity increases, but the low-k spacer structure enlarges the overlay shift budget
Solution Approach 1:
The patent applies preliminary action by forming the low-k spacer structure before the critical contact hole photolithography step. This pre-formed spacer serves as a physical reference structure that defines the acceptable overlay shift range, thereby enlarging the overlay shift budget and reducing manufacturing complexity despite decreasing feature sizes
Solution Approach 2:
The low-k spacer structure provides beforehand cushioning by creating a tolerance window for overlay shifts. The spacer's physical presence around the gate sidewalls absorbs or compensates for overlay errors that occur during subsequent photolithography steps, thereby protecting against reliability issues without increasing manufacturing complexity
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 configuration enhances the stability and reliability of semiconductor devices by reducing parasitic capacitance, broadening the overlay shift tolerance, and alleviating RC delay issues, ensuring better performance and yield.
Implementation Method 1
using a low-k material like SiOCN with a dielectric constant between 2 and 3
Data Source
AI summary
A semiconductor structure includes a substrate, a conductive region, a first insulation layer, a second insulation layer, a gate structure, a low-k spacer, a gate contact, and a conductive region contact. The low-k spacer is formed between a sidewall of the gate structure and the first insulation layer. The gate contact is landed on a top surface of the gate structure. A proximity distance between a sidewall of the gate contact and the conductive region contact along a top surface of the second insulation layer is in a range of from about 4 nm to about 7 nm. A method for manufacturing a semiconductor structure is also provided.