Semiconductor Device Trench Width Threshold Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods face difficulties in forming semiconductor structures with different threshold voltages in a common semiconductor substrate, particularly when altering the emitter region and/or body contact region areas is challenging.
Innovation Solution
A method involving the formation of trenches with varying widths in a semiconductor substrate, followed by insulating film deposition, conductive material filling, and selective etching to create regions with distinct impurity concentrations, allowing for the creation of semiconductor structures with different threshold voltages by controlling the depth and width of the trenches and subsequent impurity implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the area of emitter region and/or body contact region is changed to form semiconductor structures with different threshold voltages, then the threshold voltage can be differentiated between main region and sense region, but it becomes difficult to manufacture when such area changes are constrained
Solution Approach 1:
The patent applies local quality by creating trenches with different widths in different regions (main region vs sense region) of the semiconductor substrate. The trench width varies locally to control the etching rate, which in turn controls the depth of the conductive material and the resulting impurity concentration, achieving different threshold voltages in different regions without changing the overall emitter region area
Solution Approach 2:
The patent changes the physical parameter of trench width to control the etching process. By varying the trench width, the etching rate changes, which controls the final depth of the conductive material after etching. This parameter change (trench width) directly influences the threshold voltage through its effect on impurity concentration, providing a manufacturing approach that works when area modification is difficult
2Ease of manufacture
If general-purpose etching is used on conductive material in trenches of different widths, then the etching process is simple to implement, but the etching rate varies causing different impurity concentrations and threshold voltages
Solution Approach 1:
The patent intentionally changes the trench width parameter to control the etching rate. Wider trenches etch faster while narrower trenches etch slower, creating different depths of conductive material exposure. This parameter change is used deliberately to achieve different impurity concentrations in different regions, turning a potential source of variation into a control mechanism
Solution Approach 2:
The etching process is made to work automatically based on the trench width differences without requiring additional control mechanisms. The varying etching rates in trenches of different widths naturally produce the desired different impurity concentrations and threshold voltages, allowing the process to self-regulate the differentiation between main and sense regions
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 the manufacture of semiconductor devices with distinct threshold voltages in a common substrate, ensuring the main region has a lower threshold voltage than the sense region, even when altering the emitter or body contact region areas is difficult, thereby enhancing semiconductor device performance.
Implementation Method 1
etching the conductive material from an upper surface side of the semiconductor substrate such that each of upper surfaces of the conductive material filled inside the trenches in the first and second regions becomes lower than the upper surface of the semiconductor substrate
Implementation Method 2
forming, after the etching of the conductive material, an impurity layer (so-called, the emitter layer and/or the body contact layer) by implanting impurities from the upper surface of the semiconductor substrate to a predetermined depth range
Data Source
AI summary
A method of manufacturing a semiconductor device, the method comprising: forming trenches in an upper surface of a semiconductor substrate, the semiconductor substrate comprising a first region and a second region, the trenches in the first region having a wide width, and the trenches in the second region having a narrow width; forming insulating films on inner surfaces of the trenches; filling conductive material inside the trenches; etching the conductive material until each of upper surfaces of the conductive material filled inside the trenches becomes lower than the upper surface of the semiconductor substrate; and forming, after the etching of the conductive material, an impurity layer by implanting impurities to a predetermined depth range, the impurity layer having a concentration by which a conductivity type of a region opposed to the conductive material via each insulating film is inverted by a potential applied to the conductive material.