Self-Aligned Raised Active Area via Multi-Spacer Segmentation
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Solution Overview
Problem
Conventional semiconductor manufacturing processes face challenges in forming raised active areas by epitaxial growth, which can lead to shorts between adjacent devices due to lack of restriction and difficulty in achieving uniform height with gate electrodes, as well as limitations in implementing dual stress nitride processes.
Innovation Solution
A method involving the formation of multiple spacers on a semiconductor substrate, followed by etching to create a cavity and forming an embedded active area, allowing for self-aligned and self-limited raised active area formation, and subsequent siliciding to create a metal silicide layer, thereby restricting the range and direction of the raised active area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If epitaxial growing is performed on the entire active area to form raised active area, then the resistivity of the device extension area is reduced and contact formation is easier, but the raised active area may be grown across the isolation area to result in shorts between adjacent devices
Solution Approach 1:
The active area is divided into multiple segments using spacer structures (first spacer, second spacer, third spacer) that define discrete regions for raised active area formation. These spacers segment the epitaxial growth zone, preventing lateral expansion across isolation areas while maintaining beneficial low resistivity properties within defined boundaries.
Solution Approach 2:
Spacer structures serve as intermediary elements between the gate stack and the epitaxial growth region. The spacers act as physical barriers and templates that mediate the growth process, confining the raised active area to specific locations adjacent to the gate stack without encroaching on isolation areas.
2Manufacturing precision
If epitaxial growing is performed on the entire active area without restriction, then the raised active area can be formed to reduce resistivity, but it is difficult to make the raised active area the same height as the gate electrode
Solution Approach 1:
Multiple spacer structures are formed in advance before the epitaxial growth process. These spacers are deposited and patterned to predetermined heights and positions, establishing physical templates that predefine the boundaries and height references for the raised active area formation, enabling precise height control during subsequent growth.
Solution Approach 2:
The spacer structures serve dual functions: they act as both the patterning template and the height reference for the raised active area formation. The spacers self-limit the epitaxial growth laterally and vertically, eliminating the need for additional complex alignment and height-matching processes.
3Adaptability or versatility
If conventional epitaxial growing process is used to form raised active area, then the process is relatively simple, but it is difficult to realize the dual stress nitride process that increases mobility
Solution Approach 1:
The manufacturing process is segmented into distinct stages: spacer formation, cavity etching, embedded active area formation, and raised active area epitaxial growth. This segmentation creates discrete process windows that accommodate the dual stress nitride process steps, enabling mobility enhancement without compromising overall process simplicity.
Solution Approach 2:
The cavity structure and embedded active area are formed in advance before the raised active area epitaxial growth. This preliminary preparation creates a controlled environment that facilitates the integration of dual stress nitride processes during the final growth stage, enhancing carrier mobility while maintaining process efficiency.
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 prevents shorts between devices, allows for better profile control of the raised active area, and facilitates the implementation of dual stress nitride processes to enhance device mobility.
Implementation Method 1
the raised active area is formed by self-alignment and self-limitation
Implementation Method 2
The raised active area is formed by performing epitaxial growing on the entire active area
Implementation Method 3
siliciding the device to form a metal silicide layer
Data Source
AI summary
A method of manufacturing a semiconductor device is provided, in which after forming a gate stack and a first spacer thereof, a second spacer and a third spacer are formed; and then an opening is formed between the first spacer and the third spacer by removing the second spacer. The range of the formation for the raised active area 220 is limited by forming an opening 214 between the first spacer 208 and the third spacer 212. The raised active area 220 is formed in the opening 214 in a self-aligned manner, so that a better profile of the raised active area 220 may be achieved and the possible shorts between adjacent devices caused by an unlimited manner may be avoided. Moreover, based on such a manufacturing method, it is easy to make the gate electrode 204 to be flushed with the raised active area 220, and is also easy to implement the dual stress nitride process so as to increase the mobility of the device.