Semiconductor Contact Formation via Dual Etch Process
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Solution Overview
Problem
The existing process for forming contacts in electro-static discharge (ESD) devices and semiconductor regions using a single substrate faces challenges due to excessive removal of the polysilicon-metal dielectric (PMD) layer from the semiconductor region, leading to inadequate insulating function and contradictory etch process requirements between normal and blanket contacts.
Innovation Solution
A method is developed to form contacts using a single mask, involving a planarization process followed by a dual etch process to maximize PMD layer thickness in the ESD region and minimize its removal in the semiconductor region, ensuring the BPSG layer loss is maintained at 1000 Å or less, thereby achieving simultaneous formation of ESD and semiconductor contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an etch process is sufficiently performed to improve contact property of normal contact over ESD poly, then conductivity of normal contact is improved, but PMD layer over trench poly of semiconductor region is excessively removed
Solution Approach 1:
The patent divides the etch process into two distinct stages: a first etch process that selectively removes PMD layer from ESD device regions while preserving semiconductor regions, and a second etch process that completes the contact opening. This segmentation allows different etch conditions to be applied to different regions, resolving the contradiction between achieving good contact properties and maintaining PMD layer thickness.
Solution Approach 2:
The patent applies different etching characteristics to different regions of the substrate. The first etch process is designed to etch PMD layer selectively from ESD device regions (where thicker PMD exists) while stopping before removing PMD from semiconductor regions. This local differentiation allows the normal contact to achieve proper conductivity while the semiconductor region maintains adequate insulating layer thickness.
2Manufacturing precision
If PMD layer thickness is maintained in semiconductor region, then insulating function is achieved, but contact etch process cannot be sufficiently performed
Solution Approach 1:
The contact formation process is segmented into multiple etch steps with different objectives. The first etch process focuses on selective removal from ESD regions while the second etch process completes the opening, ensuring both adequate contact conductivity and PMD layer preservation in semiconductor regions.
Solution Approach 2:
The first etch process performs a preliminary selective removal of PMD layer from ESD device regions before the second etch process completes the contact opening. This preliminary action creates favorable conditions for the final contact formation while preserving the insulating layer where needed.
3Ease of manufacture
If single mask is used for forming both normal contact and blanket contact, then manufacturing cost is reduced, but contradictory etch requirements cannot be simultaneously satisfied
Solution Approach 1:
The etch process using a single mask is segmented into two distinct etch processes with different selectivities and endpoints. The first etch process selectively targets PMD layer in ESD regions while the second completes the contact opening, allowing a single mask to define both contact types while satisfying contradictory etch requirements through process segmentation.
Solution Approach 2:
The patent changes etch process parameters between the first and second etch processes. The first etch uses parameters optimized for selective removal from ESD regions, while the second etch uses different parameters to complete the contact opening. This parameter adjustment allows a single mask to define both contact types with different etch requirements.
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 allows for maximizing conductivity in ESD contacts and insulating properties in semiconductor contacts, while minimizing manufacturing costs by using a single mask etch process, ensuring effective contact formation without compromising the semiconductor region's PMD layer.
Implementation Method 1
after performing an isotrophic etch process, an anisotrophic process is performed to form a trench having a desired profile
Implementation Method 2
after performing an isotrophic etch process, an anisotrophic process is performed to form a trench having a desired profile
Implementation Method 3
planarizing the interlayer dielectric layer
Data Source
AI summary
A method for manufacturing a semiconductor includes forming an active region for an ESD device, an active region for a first polygate and the semiconductor, and a second polygate having a form of a blanket trench on a substrate, forming an interlayer dielectric layer including first and second insulating on the substrate, planarizing the interlayer dielectric layer, forming a contact pattern to open a portion of the interlayer dielectric layer over the first polygate, forming a first polygate trench by performing a first etch process with respect to the second insulating layer below the contact pattern, and performing a second etch process to remove the first insulating layer inside the first polygate trench and to remove the first insulating layer over the active region of the semiconductor other than the second polygate.