Semiconductor Device Outer Peripheral Depletion via P-Type Column
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Solution Overview
Problem
In semiconductor devices with trench gates, maintaining sufficient depletion in the outer peripheral region without narrowing the distance between trench gates in the cell and peripheral regions is challenging, as excessive distance leads to incomplete depletion and potential resolution failures during the exposure process.
Innovation Solution
A semiconductor device structure is introduced, featuring a p-type column region in the outer peripheral area, deeper than the body region, which is electrically connected to the source wiring to ensure complete depletion and enhance withstand voltage, while avoiding the risk of connection between trench gates in the cell and peripheral regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the trench gate in the outer peripheral region and the trench gate in the cell region is increased, then the depletion coverage is improved, but the risk of incomplete depletion in local regions increases
Solution Approach 1:
The patent introduces a column region with a specific conductivity type (opposite to the drift region) in the outer peripheral region, creating a localized structural modification. This column region is positioned between the first trenches and the second trench, providing enhanced local depletion capability without affecting the overall trench gate spacing. The local quality change ensures complete depletion in critical areas while maintaining the intended distance between trench gates.
2Manufacturing precision
If the distance between the trench gate in the outer peripheral region and the trench gate in the cell region is decreased, then the resolution failure risk is reduced, but the depletion coverage becomes insufficient
Solution Approach 1:
The column region with opposite conductivity type is strategically positioned in the outer peripheral region between the first and second trenches. This localized structural enhancement provides additional depletion capability without requiring reduced spacing between trench gates, thus maintaining manufacturing precision while improving depletion coverage.
Solution Approach 2:
The patent extends the depletion mechanism into a vertical dimension by creating a column region that reaches from the surface to a depth exceeding the body region. This vertical extension of the depletion structure complements the horizontal trench gate arrangement, providing three-dimensional depletion control that addresses the contradiction without compromising either parameter.
3Reliability
If a p-type impurity region is arranged in the outer peripheral region, then the withstand voltage is improved, but the device complexity increases
Solution Approach 1:
The column region with opposite conductivity type is introduced as a localized modification in the outer peripheral region, specifically positioned between the first trenches and the second trench. This targeted approach enhances withstand voltage by improving depletion coverage only where needed, rather than requiring complex modifications throughout the entire device structure.
Solution Approach 2:
The patent utilizes the vertical dimension by extending the column region deeper than the body region, creating a three-dimensional depletion structure. This vertical extension provides enhanced withstand voltage capability without increasing planar complexity or requiring additional lateral structures.
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 structure effectively improves the reliability and withstand voltage of the semiconductor device by ensuring complete depletion in the outer peripheral region without increasing on-resistance or causing resolution failures, thereby maintaining the expected voltage handling capabilities.
Implementation Method 1
The periphery of each trench gate is depleted at the time of turn-off, but if the above-mentioned distance is too wide, there is a risk that regions where depletion is not sufficient are locally generated
Data Source
AI summary
A plurality of first trenches is formed in a cell region and a second trench is formed in an outer peripheral region. A gate electrode and a first field plate electrode are formed in each of the plurality of first trenches, and a second field plate electrode is formed in the second trench. For example, in a drift region formed in the outer peripheral region, a p-type column region is formed in a portion sandwiched, in a Y direction, by a portion, which is located between two of the plurality of first trenches arranged next to each other, and the second trench.