Vertical Hole Profile Control via Selective Etching
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Solution Overview
Problem
In semiconductor device manufacturing, forming trenches or holes with a high aspect ratio results in a narrowing width as depth increases, leading to slanted sidewalls, which is undesirable for maintaining a vertical profile.
Innovation Solution
A method involving the formation of a preliminary hole or trench through an insulation layer, followed by the application of an etching gas such as hydrogen fluoride (HF) or fluorine (F2) with deionized water vapor, which reacts with an organic polymer photosensitive layer to selectively etch the insulation layer, increasing the width of the hole or trench while maintaining a vertical profile by vaporizing water at the upper portion and preventing vaporization at the lower portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a trench or hole with high aspect ratio is formed, then the depth increases, but the width becomes smaller and sidewalls become slanted
Solution Approach 1:
A preliminary hole is formed first through photolithography and etching, establishing the initial position and depth. Then a photosensitive layer pattern is formed to fill this preliminary hole before the selective widening etch process, preparing the structure for the subsequent vertical profile formation
Solution Approach 2:
The etching gas selectively etches the insulation layer only in specific regions where the photosensitive layer pattern is present, while leaving other regions unchanged. This localized etching widens the hole width at the bottom while maintaining the upper width, creating the vertical profile
2Length of stationary object
If the depth of the hole increases, then the aspect ratio improves, but the width narrows
Solution Approach 1:
The photosensitive layer pattern is applied selectively to fill the preliminary hole, and the etching gas reacts with this pattern to locally widen the hole width at the bottom region. This creates a width profile that is narrower at the top and wider at the bottom, compensating for the width narrowing that occurs with increased depth
Solution Approach 2:
The etching process changes the width parameter of the hole by using the photosensitive layer pattern as a template. The organic polymer in the photosensitive layer reacts with the etching gas to produce water, which then etches the silicon oxide insulation layer, increasing the hole width in a controlled manner
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 method effectively increases the width of high-aspect-ratio holes or trenches, ensuring a vertical profile by selectively etching the insulation layer, thereby addressing the issue of narrowing widths with increasing depth.
Implementation Method 1
an etching gas including hydrogen fluoride (HF) or fluorine (F2) is provided onto the photosensitive layer pattern to etch the insulation layer
Implementation Method 2
water generated by the reaction of the etching gas and an upper (remote) portion of the photosensitive layer pattern that is remote from the substrate may be vaporized
Data Source
AI summary
In a method of forming a hole, an insulation layer is formed on a substrate, and a preliminary hole exposing the substrate is formed through the insulation layer. A photosensitive layer pattern including an organic polymer is then formed on the substrate to fill the preliminary hole. An etching gas including hydrogen fluoride (HF) or fluorine (F2) is then provided onto the photosensitive layer pattern to etch the insulation layer so that width of the preliminary hole is increased.