Semiconductor Insulator Structure Etching Control
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Solution Overview
Problem
In semiconductor manufacturing, capillary etching effects during the buffered oxide etch process lead to excessive etching of silicon oxide spacers, causing voids and subsequent device failure due to uncontrolled etching and crack formation.
Innovation Solution
A method involving forming a patterned second semiconductor layer with an actual thickness greater than the target thickness, followed by an etching process that removes the second insulator layer serving as a spacer, thereby preventing capillary etching and ensuring controlled etching, and rounding off edges to increase capping layer density for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a buffered oxide etch process is performed to etch silicon oxide layers, then the etching process can remove the buffer oxide layer, but the capillary silicon dioxide spacer is excessively etched due to capillary effects, causing uncontrolled etching and device failure
Solution Approach 1:
The patent removes the problematic capillary silicon dioxide spacer from the structure before performing the buffered oxide etch process. By extracting the element that causes capillary effects, the etching process can proceed without uncontrolled etching, thus improving both etching precision and device reliability
Solution Approach 2:
The patent introduces a nitride layer as an intermediary material to replace the silicon dioxide spacer. This nitride layer serves as a mediator that prevents capillary effects during etching while still providing the necessary structural function, resolving the contradiction between etching control and device reliability
2Manufacturing precision
If the density of silicon dioxide is increased by annealing treatment to reduce capillary etching, then the etch rate is reduced, but the device reliability is not sufficiently improved
Solution Approach 1:
The patent changes the material parameter from silicon dioxide to nitride, which fundamentally alters the etching behavior. This material substitution provides better etching control and significantly improves device reliability, overcoming the limitations of annealing treatment
3Manufacturing precision
If capillary silicon dioxide is replaced with silicon nitride to prevent capillary etching, then etching control is improved, but the silicon nitride cannot be etched cleanly and causes fall off (peeling) leading to device defects
Solution Approach 1:
The patent performs preliminary removal of the nitride layer in specific regions before the buffered oxide etch process. This preliminary action prevents the nitride layer from causing peeling and device defects while maintaining its beneficial properties of preventing capillary etching during the main etching 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 prevents capillary etching effects, enhances device reliability by controlling the etching process, and reduces the likelihood of cracks, thereby improving the performance and durability of semiconductor devices.
Implementation Method 1
In the BOE process, due to the capillary effect, the portion of the silicon oxide in the vicinity of the spacer is etched quickly, far beyond the normal etch rate
Implementation Method 2
performing an etching process on the patterned second semiconductor layer until the second semiconductor layer has the target thickness, and concurrently removing the second insulator layer
Data Source
AI summary
A semiconductor device includes a semiconductor substrate, a first semiconductor layer on the semiconductor substrate and having an exposed portion of a lower surface, a capping layer on the first semiconductor layer, a second semiconductor layer below the capping layer and having a side surface substantially in full contact with the capping layer, a cavity defined by the first semiconductor layer, the second semiconductor layer, and the capping layer, and a through-hole passing through the capping layer and the second semiconductor layer and extending to the cavity.