Epitaxial Source/Drain Selectivity via Single Mask Process
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Solution Overview
Problem
The existing FinFET fabrication processes require multiple photolithography steps and masks, leading to increased complexity, cost, and epitaxial layer loss due to the use of separate masks for N-type and P-type epitaxial source/drain regions, which complicates semiconductor manufacturing.
Innovation Solution
A method using a single photolithography process and mask to form both N-type and P-type epitaxial source/drain regions, where a highly-doped N-type layer prevents epitaxial growth of the P-type layer, reducing the need for additional masking layers and simplifying the process while maintaining selectivity between the regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate photolithography processes and masks are used to define N-type and P-type epitaxial source/drain regions, then selectivity between regions is achieved, but process complexity and cost increase
Solution Approach 1:
The highly-doped N-type layer automatically prevents epitaxial growth of the P-type layer through its inherent material properties, eliminating the need for separate photolithography masks and processes for N-type regions. The layer serves its own function as both a conductive element and a growth barrier.
Solution Approach 2:
The patent combines the functions of the highly-doped N-type layer and the epitaxial growth barrier into a single structural element. This merging eliminates the need for separate masking layers and photolithography processes, reducing process complexity while maintaining selectivity.
2Manufacturing precision
If separate photolithography processes and masks are used to define N-type and P-type epitaxial source/drain regions, then region definition is achieved, but manufacturing cost increases
Solution Approach 1:
The highly-doped N-type layer performs dual functions: providing electrical conduction and preventing unwanted epitaxial growth. This self-service capability eliminates the need for additional expensive masks and photolithography processes, directly reducing manufacturing costs.
Solution Approach 2:
The patent extracts the epitaxial growth barrier function from the photolithography masking system and embeds it directly into the highly-doped N-type layer structure, eliminating the need for separate masking materials and processes.
3Manufacturing precision
If additional masking layers are deposited and removed, then selectivity is maintained, but epitaxial layer loss occurs
Solution Approach 1:
The highly-doped N-type layer inherently prevents epitaxial growth without requiring additional masking layers to be deposited and removed. This eliminates the mechanical stress and potential damage associated with multiple masking operations, preventing epitaxial layer loss.
Solution Approach 2:
The patent converts the potential harm of needing multiple masking operations into a benefit by using the highly-doped N-type layer's inherent material properties to provide the barrier function, thereby eliminating the harmful effects of repeated masking and unmasking cycles on the epitaxial layers.
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 reduces the complexity and cost of forming epitaxial source/drain regions, minimizes epitaxial layer loss, and enhances device reliability by using fewer masking layers and ensuring epitaxial growth selectivity between N-type and P-type regions.
Implementation Method 1
a barrier layer is formed over the first epitaxial layer... an epitaxial second type source/drain layer is selectively formed over a second group of fins
Data Source
AI summary
A method for forming an epitaxial source/drain structure in a semiconductor device includes providing a substrate having a plurality of fins extending from the substrate. In some embodiments, a liner layer is formed over the plurality of fins. The liner layer is patterned to expose a first group of fins of the plurality of fins in a first region. In some embodiments, a first epitaxial layer is formed over the exposed first group of fins and a barrier layer is formed over the first epitaxial layer. Thereafter, the patterned liner layer may be removed. In various examples, a second epitaxial layer is selectively formed over a second group of fins of the plurality of fins in a second region.