Raised Metal Semiconductor Alloy Self-Aligned MOL Contacts
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Solution Overview
Problem
Conventional methods for forming middle-of-line (MOL) contacts in semiconductor devices face challenges due to the miniaturization of device dimensions, making it difficult to form contact via holes between narrow gate structures and fill them with low resistance metals without photolithographic patterning and etching.
Innovation Solution
The method involves forming raised metal semiconductor alloy regions by reacting a metal layer with a semiconductor material in source/drain regions, allowing these regions to be self-aligned with gate structures, eliminating the need for lithographic patterning and etching by expanding to the same height as the gate structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithographic patterning and etching are used to form contact via holes, then contact formation is achievable, but the process becomes increasingly difficult and complex as device dimensions scale down
Solution Approach 1:
The patent performs preliminary actions by forming raised source/drain regions and depositing metal layers before gate patterning. This allows the contact regions to be pre-formed and self-aligned, eliminating the need for subsequent photolithographic patterning and etching steps to create contact via holes between gates.
Solution Approach 2:
The patent inverts the conventional sequence by forming contacts before final gate patterning. Instead of forming contacts after gates are patterned, the method raises contact regions first, then patterns gates around them, thereby eliminating the need for difficult between-gate patterning operations.
2Manufacturing precision
If direct patterning is used to form contact via holes between narrow gate structures, then contact alignment is achieved, but the aspect ratio of via holes increases making complete filling with low resistance metal difficult
Solution Approach 1:
The patent performs preliminary actions by forming raised source/drain regions and depositing metal layers before gate patterning. This allows the contact regions to be pre-formed and self-aligned, eliminating the need for subsequent photolithographic patterning and etching steps to create contact via holes between gates.
Solution Approach 2:
The patent transitions from planar contact formation to three-dimensional raised contact regions. By forming contacts that extend vertically above the gate structures, the method enables complete metal filling without requiring high aspect ratio via holes, thus improving filling reliability.
3Ease of manufacture
If conventional contact formation methods are used, then contact via holes can be formed, but lithographic patterning and etching processes are required between functional gate structures
Solution Approach 1:
The patent performs preliminary actions by forming raised source/drain regions and depositing metal layers before gate patterning. This allows the contact regions to be pre-formed and self-aligned, eliminating the need for subsequent photolithographic patterning and etching steps to create contact via holes between gates.
Solution Approach 2:
The patent employs self-service by using the gate structures themselves as alignment references for the raised contact regions. The contacts are formed to be self-aligned with the gates, eliminating the need for separate lithographic patterning and etching processes to define contact locations between gates.
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 enables the formation of self-aligned MOL contacts without photolithographic patterning and etching, improving the reliability and efficiency of contact formation in semiconductor devices by ensuring complete filling of metal semiconductor alloy regions, which are coplanar with gate structures.
Implementation Method 1
The metal layer includes a metal capable of forming a metal semiconductor alloy with a large volume expansion such that the resulting metal semiconductor alloy regions can be raised to a same height as that of the functional gate structures
Data Source
AI summary
A method to form self-aligned middle-of-line (MOL) contacts between functional gate structures without the need of lithographic patterning and etching by using raised metal semiconductor alloy regions is provided. Raised metal semiconductor alloy regions are formed by reacting a metal layer with a semiconductor material in raised semiconductor material regions formed on portions of at least one active region of a substrate located between functional gate structures. The metal layer includes a metal capable of forming a metal semiconductor alloy with a large volume expansion such that the resulting metal semiconductor alloy regions can be raised to a same height as that of the functional gate structures. As a result, no lithographic patterning and etching between functional gate structures are needed when forming MOL contacts to these raised metal semiconductor alloy regions.