Insulated-Gate Semiconductor Device Dummy Trench Screening
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Solution Overview
Problem
Existing methods for insulated-gate semiconductor devices with trench gate structures face challenges in screening defects of gate insulating films in dummy trenches independently of gate trenches, leading to increased particle generation and reduced resistance to time-dependent dielectric breakdown (TDDB) due to the need for high voltage testing.
Innovation Solution
The solution involves a method where a dummy electrode is buried in a dummy trench and a gate electrode in a gate trench, with a stacked interlayer insulating film structure, allowing for independent testing of the insulating properties of the gate insulating films in dummy trenches, reducing the need for high voltage and minimizing particle generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high voltage is applied during screening test of gate insulating films in all trenches, then defective elements can be detected, but a large amount of particles are generated when defective elements are broken
Solution Approach 1:
The patent segments the trenches into two types: dummy trenches containing dummy electrodes and gate trenches containing gate electrodes. By structurally differentiating these trenches, the patent enables selective screening of gate insulating films in dummy trenches only, allowing for lower voltage application during testing and thereby reducing particle generation from defective element breakdown.
2Object-generated harmful factors
If screening conditions are changed to decrease particle amount, then fewer particles are generated, but an additional screening test is required after manufacturing, reducing resistance to time-dependent dielectric breakdown
Solution Approach 1:
The patent performs preliminary screening of gate insulating films in dummy trenches during the manufacturing process itself, rather than requiring a separate post-manufacturing test. This preliminary action ensures that defective gate insulating films are detected and eliminated early, maintaining high resistance to time-dependent dielectric breakdown without needing additional screening steps afterward.
3Productivity
If screening is canceled after completion of manufacturing process, then fewer steps are required, but damage caused in the rest of the process cannot be screened out
Solution Approach 1:
The patent implements screening of gate insulating films in dummy trenches as a preliminary step during the manufacturing process, specifically after forming the gate insulating film and before completing subsequent manufacturing steps. This timing ensures that defects are detected early while maintaining manufacturing efficiency, as the screening is integrated into the existing process flow rather than being an additional post-manufacturing step.
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 enables effective screening of defects in gate insulating films in dummy trenches without affecting the gate trenches, reducing particle generation and maintaining resistance to TDDB, thus improving the manufacturing process efficiency and device reliability.
Implementation Method 1
a gate insulating film; burying a dummy electrode in the dummy trench via the gate insulating film and burying a gate electrode in the gate trench via the gate insulating film
Implementation Method 2
a first interlayer insulating film provided on the gate electrode; and a second interlayer insulating film provided on the dummy electrode
Data Source
AI summary
A method of manufacturing an insulated-gate semiconductor device, includes: digging a gate trench and a dummy trench; burying a dummy electrode in the dummy trench via a gate insulating film and burying a gate electrode in the gate trench via the gate insulating film; exposing an upper portion of the dummy electrode and selectively forming an insulating film for testing so as to cover the gate electrode; depositing a conductive film for testing on the dummy electrode and the insulating film for testing; and selectively testing an insulating property of the gate insulating film in the dummy trench by applying a voltage between the conductive film for testing and the charge transport, region.