Polycrystalline Silicon IGFET Trench Isolation
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Solution Overview
Problem
The production of power semiconductor components with integrated field effect transistors (IGFETs) and other semiconductor components is complex due to the need for multiple mask steps in patterning polycrystalline silicon regions, which increases process complexity and reduces efficiency.
Innovation Solution
A method involving the formation of trenches for IGFET and semiconductor elements, followed by filling with polycrystalline silicon and a chemical mechanical polishing step to separate and isolate the structures, reducing the need for additional mask steps and simplifying the process by achieving a planar surface topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mask steps are used for patterning polycrystalline silicon regions of different components, then the precision of component formation is improved, but the device complexity and production time increase
Solution Approach 1:
The patent divides the production process into two main stages: first, forming all trenches simultaneously using a single mask step; second, filling trenches with polycrystalline silicon and using chemical mechanical polishing to separate different component regions. This segmentation reduces the number of mask steps while maintaining precision through controlled material deposition and removal.
Solution Approach 2:
The patent performs preliminary trench formation for all components (IGFETs, diodes, resistors, capacitors, sensors) simultaneously before component-specific patterning. By pre-defining all trench locations in one mask step, the subsequent component formation can proceed with simpler, component-specific processing steps.
2Manufacturing precision
If multiple mask steps are used for patterning polycrystalline silicon regions, then the manufacturing precision is improved, but the productivity decreases
Solution Approach 1:
The patent merges the formation of all trench structures into a single simultaneous process step, filling multiple trench types (IGFET gates, diode regions, resistor regions, capacitor regions, sensor regions) in one operation. This consolidation maintains precision while significantly improving productivity by eliminating sequential mask steps.
Solution Approach 2:
The patent implements continuous processing where trench formation, polycrystalline silicon filling, and chemical mechanical polishing occur in sequence without interruption. This continuous action eliminates idle time between discrete mask steps, maintaining high precision while maximizing production efficiency.
3Ease of manufacture
If chemical mechanical polishing is used to separate polycrystalline silicon structures, then the ease of manufacture is improved, but the manufacturing precision may be affected
Solution Approach 1:
The patent replaces complex mechanical masking and etching systems with chemical mechanical polishing. This substitution simplifies the manufacturing process by using a single, well-controlled polishing step to define component boundaries, achieving both ease of manufacture and sufficient precision for power semiconductor components.
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 simplifies the production process by eliminating further mask steps and ensuring electrical isolation of polycrystalline silicon structures, enhancing product yield and reducing the complexity of forming component regions.
Implementation Method 1
carrying out a chemical mechanical polishing step in order to remove polycrystalline silicon present above the first trench and the second trench
Data Source
AI summary
A semiconductor device includes a semiconductor body, having a first surface, a gate electrode structure, which includes polycrystalline silicon, of an IGFET in a first trench extending from the first surface into the semiconductor body. The device also includes a semiconductor element, which is different from the gate electrode structure of the IGFET and includes polycrystalline silicon, in a second trench extending from the first surface into the semiconductor body, wherein the polycrystalline silicon of the IGFET and of the semiconductor element different therefrom ends below a top side of an insulation layer adjoining the first surface of the semiconductor body.