Trench Gate Structure with Slope Insulating Spacer
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Solution Overview
Problem
Conventional trench gate structures in semiconductor manufacturing are limited by trench depth, contact hole depth, and polysilicon thickness, leading to restricted design flexibility and increased costs due to the need for additional mask layers.
Innovation Solution
A method involving the formation of an insulating pad with a slope structure, a hard mask, and polysilicon gate openings, allowing for independent trench and contact hole depths, and eliminating the need for extra lithography masks by integrating polysilicon gate lithography with device lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional trench gate structure is used with enlarged lead-out trenches and contact holes, then existing mask layers can be utilized without increasing mask cost, but design flexibility is limited by trench depth, polysilicon thickness, and contact hole depth
Solution Approach 1:
The patent divides the polysilicon gate into two independent parts: a trench gate portion within the trench and a lead-out portion extending onto the insulating pad. This segmentation allows independent optimization of trench depth and contact hole depth without mutual constraints, directly resolving the design flexibility limitation while maintaining process simplicity through integrated lithography.
2Reliability
If contact hole depth is increased to reach deeper polysilicon, then better electrical contact is achieved, but risk of leakage increases and process opening size must be reduced
Solution Approach 1:
The insulating pad acts as an intermediary structure between the contact hole and the substrate. By extending the polysilicon gate onto the insulating pad surface, the contact hole can be formed with larger opening size and controlled depth without penetrating through to cause substrate leakage, while still achieving reliable electrical contact to the polysilicon gate.
3Manufacturing precision
If additional mask layers are added to achieve precise trench gate patterning, then manufacturing precision is improved, but production cost increases
Solution Approach 1:
The patent merges the trench gate lithography with the device polysilicon lithography into a single lithography step. The same photoresist pattern defines both the device active area and the trench gate opening, eliminating the need for separate mask layers while maintaining precise patterning through the integrated exposure and development process.
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 enhances design flexibility, reduces the risk of leakage, and maintains cost-effectiveness by allowing independent control of trench and contact hole depths without increasing mask layer costs.
Implementation Method 1
etching an exposed hard mask by the opening, wherein the insulating pad forms a polysilicon gate pull-up area corresponding to the opening due to an over-etching of the hard mask
Implementation Method 2
performing a gate oxide oxidation, forming a gate oxide layer on an inner surface of the trench
Implementation Method 3
depositing polysilicon in the trench, forming a polysilicon gate
Data Source
AI summary
A trench gate structure and a manufacturing method therefor. The trench structure comprises a substrate (10), a trench on the surface of the substrate (10), an insulating spacer (20) on the substrate (10), a gate oxide layer (41) on the inner surface of the trench, and a polysilicon gate (40) on the gate oxide layer (41). The insulating spacer (20) abuts against the trench by means of a slope structure (21) of the insulating spacer; the polysilicon gate (40) extends onto the insulating spacer (20) along the slope structure (21) in the trench; the insulating spacer (20) comprises a polysilicon gate pull-up area (22) that is concave downwards with respect to other parts of the insulating spacer (20); the polysilicon gate (40) extending out of the trench is rested on the polysilicon gate pull-up area (22).