Gate Contact Silicide Structure for High-K Metal Gate Stability
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Solution Overview
Problem
The small size of the silicide portion in the contact structure of a gate structure leads to instability and high resistance, making it difficult to form a stable and effective contact structure, especially due to the limitations of the hard mask layer and high aspect ratio trenches, which result in electron and hole scattering and damage during the high-K metal gate last process.
Innovation Solution
The method involves forming a contact structure by etching an oxidation layer and a sidewall layer between the metal gates to expose the silicon substrate, depositing a silicide portion, and then using a metal glue layer to define a trench for a metal plug, reducing the aspect ratio and minimizing damage from high temperatures, thereby enhancing the contact area and critical dimension uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a contact structure is formed using conventional lithography and etching with a hard mask layer, then the contact structure can be patterned, but the silicide portion becomes too small leading to high resistance and instability
Solution Approach 1:
The patent introduces a sidewall layer that adds a vertical dimension to the contact structure formation process. By forming the sidewall layer on the hard mask layer and using it as an etch stop, the process achieves better dimensional control and prevents the silicide portion from becoming too small, thereby maintaining reliability while achieving precise patterning.
Solution Approach 2:
The sidewall layer acts as an intermediary between the hard mask layer and the silicide formation process. It provides an additional protective layer that prevents direct contact between the etchant and the hard mask layer, ensuring that the silicide portion maintains adequate size and stability while still allowing precise contact structure formation.
2Manufacturing precision
If the silicide portion is made small to achieve precise contact structure, then the contact area is reduced, but the resistance increases and stability decreases
Solution Approach 1:
By adding the sidewall layer dimension, the patent enables precise contact structure formation without forcing the silicide portion to be excessively small. The sidewall layer provides lateral confinement that maintains adequate silicide area while achieving the desired contact precision, thus preventing high resistance and instability.
3Adaptability or versatility
If a high-K metal gate last process is used to improve gate performance, then the contact structure stability is compromised due to electron and hole scattering and damage from high temperatures
Solution Approach 1:
The sidewall layer serves as a protective cushion formed before the high-K metal gate last process. It shields the contact structure from the harmful effects of high temperatures and plasma exposure during subsequent processing steps, preventing electron and hole scattering while allowing the gate structure to achieve optimal performance.
Solution Approach 2:
The sidewall layer acts as an intermediary protective barrier between the contact structure and the harsh processing conditions of the high-K metal gate last process. It absorbs the damage from high temperatures and plasma, allowing the contact structure to remain stable while the gate structure achieves its desired performance characteristics.
4Length of moving object
If the aspect ratio of the trench is high to achieve deep contact, then the contact area is reduced and manufacturing difficulty increases
Solution Approach 1:
The sidewall layer acts as an intermediary etch stop layer that enables better control over the trench formation process. It allows the etching to proceed to the required depth while providing a defined stopping point, thereby reducing the effective aspect ratio and simplifying the manufacturing process without compromising trench depth.
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 results in a more stable and efficient contact structure with reduced resistance and improved critical dimension uniformity, minimizing defects and damage from high-temperature processes, and allowing for better alignment and flexibility in the contact structure formation.
Implementation Method 1
an oxidation layer and a first sidewall layer disposed between a first metal gate and a second metal gate are etched to expose an underlying silicon substrate
Implementation Method 2
A silicide portion defined by a contact profile in the exposed portion of the silicon substrate is deposited
Implementation Method 3
A metal glue layer is deposited around the first metal gate and the second metal gate defining a trench above the silicide portion
Implementation Method 4
A metal plug is deposited within the trench
Data Source
AI summary
A method of forming a contact structure of a gate structure is provided. In the method, an oxidation layer and a first sidewall layer disposed between a first metal gate and a second metal gate are etched to expose an underlying silicon substrate. A silicide portion defined by a contact profile is deposited in the exposed portion of the silicon substrate. A second sidewall layer substantially covers the first sidewall layer and at least partially covering the silicide portion is formed after depositing the silicide portion. A metal glue layer is deposited around the first metal gate and the second metal gate defining a trench above the silicide portion. A metal plug is deposited within the trench.