Dry Etching Method for Silicon Substrates
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In the manufacturing of semiconductor devices, dry etching of silicon substrates for three-dimensional structures poses challenges in minimizing sidewall damage and preventing microtrench formation, which affects the performance and accuracy of metal insulator semiconductor field effect transistors (MISFETs).
Innovation Solution
A dry etching method involving a plasma etching process with specific pressure and radio frequency power settings, where the pressure is set between 1 mTorr and 100 mTorr, and the etching is carried out while satisfying certain equations related to self-bias voltage and power density, to minimize sidewall damage and microtrench formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional dry etching is used for three-dimensional structure formation, then etching depth can be achieved, but sidewall damage and microtrench formation occur
Solution Approach 1:
The patent applies parameter changes by optimizing the relationship between pressure and self-bias voltage. Specifically, it establishes that the absolute value of self-bias voltage should satisfy |Vs| ≥ -1.7P + 295 (where P is pressure in mTorr), and pressure should be maintained between 1-100 mTorr. This parameter optimization controls ion incident angle and energy distribution, enabling deep etching while minimizing sidewall damage.
Solution Approach 2:
The patent employs dynamics by dynamically adjusting the balance between ion bombardment energy and pressure during the etching process. By controlling the time-varying relationship between these parameters according to the established equation, the process adapts to maintain optimal ion incidence conditions throughout the etching duration, preventing microtrench formation while achieving required etching depths.
2Length of moving object
If conventional dry etching is used for three-dimensional structure formation, then etching depth can be achieved, but microtrench formation occurs
Solution Approach 1:
The patent uses parameter changes to control the etching profile by optimizing pressure and self-bias voltage relationships. The established equation |Vs| ≥ -1.7P + 295 ensures that ion incident angles remain within optimal ranges throughout the etching process, maintaining vertical sidewall profiles and preventing microtrench formation even at deep etching depths.
Solution Approach 2:
The patent implements feedback control by continuously monitoring and adjusting the relationship between pressure and self-bias voltage during the etching process. The control system ensures that the parameters remain within the optimal region defined by the equation, automatically compensating for deviations to maintain consistent vertical profile and prevent microtrench formation.
3Productivity
If high ion incidence is used to increase etching rate, then productivity improves, but sidewall damage increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the combined parameters of pressure and self-bias voltage rather than increasing ion incidence alone. The relationship |Vs| ≥ -1.7P + 295 ensures that etching proceeds at high rates through optimized chemical reactions and controlled ion bombardment, while the specific parameter combination prevents excessive ion damage to sidewalls by controlling ion incident angle and energy distribution.
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
The method effectively prevents sidewall damage and microtrench formation, ensuring vertical trench formation and maintaining the performance and stability of MISFETs, particularly in three-dimensional structures.
Implementation Method 1
generating a plasma by discharging an etching gas in the processing chamber
Implementation Method 2
etching the silicon substrate by the plasma
Implementation Method 3
supplying to the electrode a radio frequency power for attracting ions from the plasma
Implementation Method 4
supplying to the electrode a radio frequency power
Data Source
AI summary
In a dry etching method, a silicon substrate is mounted on an electrode arranged in a processing chamber; a plasma is generated by discharging an etching gas in the processing chamber; a radio frequency power for attracting ions from the plasma is supplied to the electrode; and the silicon substrate is etched by the plasma. A pressure inside the processing chamber is set as 1 mTorr to 100 mTorr, and the etching is carried out while satisfying the following equation: yM≧2.84*10−3x+0.28, where yM is a power density of the radio frequency power per unit area of the electrode and x is the pressure inside the processing chamber.