SOI Contact Plug Structure for Simpler Backside Interconnection
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Solution Overview
Problem
Current fabrication processes for contact plugs in semiconductor devices on silicon-on-insulator (SOI) substrates are complex and costly, particularly in forming different-sized contact plugs for active devices and backside contacts, necessitating a simpler and more cost-effective method.
Innovation Solution
A method involving the formation of first and second contact plugs with specific surface configurations, where the top surface of the second contact plug protrudes above the interlayer dielectric layer, and subsequent metal interconnective processes to connect these plugs, ensuring efficient electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current fabrication process is used to form different-sized contact plugs, then electrical connectivity is achieved, but fabrication complexity and cost increase
Solution Approach 1:
The patent merges the formation of first and second contact plugs into a single fabrication sequence. The method forms contact holes through the interlayer dielectric layer, then fills them with conductive material to create both contact plug types simultaneously, eliminating the need for separate fabrication processes for each contact plug size.
Solution Approach 2:
The patent creates a universal fabrication approach where the same contact hole formation and filling process produces both first contact plugs (connecting to active devices) and second contact plugs (penetrating the SOI substrate). This multi-functional process handles different contact plug requirements through a single standardized procedure.
2Reliability
If current fabrication process is used to form different-sized contact plugs, then electrical connectivity is achieved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple fabrication steps into one integrated process. By forming all contact holes and filling them with conductive material in a single sequence, the method reduces the total number of fabrication steps, thereby lowering manufacturing costs while maintaining electrical connectivity.
Solution Approach 2:
The patent varies parameters such as contact hole depth and conductive material filling depth to produce different contact plug types from the same base process. This allows cost-effective manufacturing by using a single fabrication recipe with adjustable parameters rather than requiring entirely separate processes.
3Reliability
If contact plugs are formed with protruding top surfaces, then electrical connectivity is enhanced, but material loss increases
Solution Approach 1:
The patent performs preliminary planning of contact hole dimensions and conductive material filling depths to ensure that protruding top surfaces are achieved only where needed for enhanced connectivity. By pre-determining the exact material deposition parameters, the method minimizes excess material usage while still achieving the required protrusion for electrical connection.
Solution Approach 2:
The patent applies different filling depths of conductive material in different contact holes based on local requirements. First contact plugs may have different protrusion heights than second contact plugs, optimizing material usage by providing protrusion only where it is needed for electrical connectivity rather than uniformly across all contact plugs.
Data Source
AI summary
A semiconductor device includes: a substrate having a first semiconductor layer, an insulating layer, and a second semiconductor layer; an active device on the substrate; an interlayer dielectric (ILD) layer on the active device; a first contact plug in the ILD layer and electrically connected to the active device; and a second contact plug in the ILD layer and the insulating layer, wherein a top surface of the second contact plug is higher than a top surface of the ILD layer.