Sacrificial Etch Stop Layer for Semiconductor Contact Formation
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Solution Overview
Problem
As design rules shrink in semiconductor fabrication, forming reliable electrical contacts between discrete components becomes increasingly difficult due to smaller contact areas and the challenge of maintaining electrical interface quality during dielectric layer removal, which can damage the source/drain regions.
Innovation Solution
A sacrificial etch stop layer is formed on the source/drain region to protect the electrical interface during dielectric removal, using specific materials like gallium oxide or tungsten, and then selectively etched to expose a contact surface, minimizing damage and ensuring a stable electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If design rules are shrunk to increase memory density, then memory device capacity increases, but manufacturing precision and reliability of electrical contacts deteriorate
Solution Approach 1:
A sacrificial etch stop layer is deposited on the source/drain region before forming the contact hole. This preliminary action protects the source/drain region from damage during subsequent etching processes, ensuring that the contact surface is exposed without compromising the underlying semiconductor structure, thereby maintaining manufacturing precision at scaled dimensions
Solution Approach 2:
The sacrificial etch stop layer acts as an intermediary between the etch process and the source/drain region. It provides a protective interface that allows the etch process to proceed while preventing direct contact between the etchant and the sensitive source/drain region, thus preserving electrical contact quality during contact formation
2Quantity of substance
If design rules are shrunk to increase memory density, then memory device capacity increases, but reliability of electrical contacts deteriorates
Solution Approach 1:
The sacrificial etch stop layer is deposited in advance to protect the source/drain region during contact hole formation. This preliminary protective measure ensures that the electrical interface is not damaged by the etching process, maintaining contact reliability even as device dimensions are reduced to increase density
Solution Approach 2:
The sacrificial etch stop layer provides a cushioning effect by absorbing the mechanical and chemical stress of the etching process before it reaches the source/drain region. This beforehand protection ensures that the electrical contact interface remains intact and reliable, preventing damage that would otherwise occur during contact formation at scaled dimensions
3Ease of manufacture
If dielectric layer is removed to form contact, then contact surface is exposed, but source/drain region is damaged
Solution Approach 1:
The sacrificial etch stop layer serves as an intermediary protective layer between the etch process and the source/drain region. It allows the dielectric layer to be removed and the contact surface to be exposed while preventing the etchant from directly damaging the source/drain region, thus enabling contact formation without harmful effects
Solution Approach 2:
The sacrificial etch stop layer is a temporary, disposable structure that is deposited, serves its protective function during contact hole formation, and then is removed. This short-living protective layer enables the manufacturing process to proceed easily while protecting the permanent source/drain region from damage
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 reduces damage to the source/drain regions during contact formation, maintaining the quality of the electrical interface and enhancing the reliability of memory cell operation by providing a stable and improved contact surface for vertical access devices.
Implementation Method 1
The dielectric layer is removed using a first etch process to expose the sacrificial etch stop layer. The sacrificial etch stop layer is removed using a second etch process to expose a contact surface on the second source/drain region.
Data Source
AI summary
Systems, methods and apparatus are provided for a semiconductor structure. An example method includes a method for forming a contact surface on a vertically oriented access devices. The method includes forming a first source/drain region and a second source/drain region vertically separated by a channel region, forming a sacrificial etch stop layer on a first side of the second source/drain region, wherein the channel region is in contact with a second side of the second source/drain region, forming a dielectric layer on a first side of the sacrificial etch stop layer, where the second source/drain region is connected to a second side of the sacrificial etch stop layer, removing the dielectric layer using a first etch process to expose the sacrificial etch stop layer, and removing the sacrificial etch stop layer using a second etch process to form a contact surface on the second source/drain region.