Sacrificial Sidewall Spacer for Contact Plug Formation
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Solution Overview
Problem
Conventional methods for forming contact plugs in semiconductor devices require multiple masks, making it challenging to achieve precise control over feature size and optimizing device performance, particularly as feature sizes scale down.
Innovation Solution
A method involving the formation of a sacrificial sidewall spacer over a sidewall spacer, followed by its removal to create a contact space, which is then filled with a conducting layer, allowing for self-aligning processes that reduce the number of masks needed and enhance contact region coverage and carrier mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mask is used in etching the interlayer dielectric layer to form the contact hole, then the contact hole can be formed with conventional processes, but the manufacturing precision deteriorates as the contact hole size is reduced
Solution Approach 1:
The patent introduces a sacrificial sidewall spacer as an intermediary structure to define the contact hole position and size. This sacrificial layer acts as a mediator between the sidewall spacer and the interlayer dielectric layer, enabling precise contact hole formation without requiring additional masks. The sacrificial sidewall spacer is formed between the sidewall spacer and the interlayer dielectric layer, and its removal creates the contact hole with high precision control.
Solution Approach 2:
The patent performs preliminary action by forming the sacrificial sidewall spacer before forming the interlayer dielectric layer. This preliminary structure preparation allows the contact hole position and size to be pre-determined by the sacrificial layer dimensions, enabling precise control before the actual contact hole etching process begins.
2Productivity
If the contact hole size is reduced to scale with semiconductor features, then device density is improved, but the conventional mask-based etching process can no longer achieve the desired precision
Solution Approach 1:
The sacrificial sidewall spacer serves as a mediator that enables precise formation of smaller contact holes. By using this intermediary structure, the patent achieves high precision contact hole formation at reduced sizes that are difficult to achieve with conventional mask-based etching processes.
Solution Approach 2:
The patent changes the formation parameters by introducing a sacrificial layer with specific material properties that allow for precise dimensional control. The sacrificial sidewall spacer's thickness and material characteristics are optimized to achieve the desired contact hole size and shape, enabling scaling while maintaining manufacturing precision.
3Ease of manufacture
If multiple masks are used in the contact plug formation process, then the contact plug can be formed with conventional processes, but the manufacturing complexity and process time increase
Solution Approach 1:
The patent merges the contact hole definition function with the sidewall spacer structure by introducing the sacrificial sidewall spacer. This combines multiple functions (sidewall protection and contact hole positioning) into a single integrated structure, eliminating the need for separate mask steps and reducing overall process time.
Solution Approach 2:
The sacrificial sidewall spacer acts as an intermediary that enables contact hole formation without requiring additional mask steps. This intermediary structure integrates the positioning function into the existing sidewall spacer formation process, reducing manufacturing complexity and process time.
Data Source
AI summary
The invention provides a method for forming a contact plug, comprising: forming a gate, a sidewall spacer, a sacrificial sidewall spacer, a source region and a drain region on a substrate, wherein the sidewall spacer is formed around the gate, the sacrificial sidewall spacer is formed over the sidewall spacer, and the source region and the drain region are formed within the substrate and on respective sides of the gate; forming an interlayer dielectric layer, with the gate, the sidewall spacer and the sacrificial sidewall spacer being exposed; removing the sacrificial sidewall spacer to form a contact space, the sacrificial sidewall spacer material being different from that of the gate, the sidewall spacer and the interlayer dielectric layer; forming a conducting layer to fill the contact space; and cutting off the conducting layer, to form at least two conductors connected to the source region and the drain region respectively.