Resist Protective Film Etching for Pattern Accuracy Retention
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Solution Overview
Problem
Conventional etching methods for semiconductor and micro mechanical parts face issues such as RIE-lag, where different aspect ratios lead to varying etching rates, resin resist degradation, and the need for multiple apparatuses and processes, resulting in contamination and reduced pattern accuracy.
Innovation Solution
An etching method involving repetitive etching steps with a resist protective film-forming step using plasma CVD to form a silicon fluoride oxide film, controlled by alternating electrode frequencies and gas compositions, maintains resist layer thickness and pattern accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fluorine-based plasma gas or oxygen-based plasma gas is used for etching treatment or ashing treatment, then etching rate is improved, but resin resist disappears and pattern accuracy deteriorates
Solution Approach 1:
A protective film is introduced as an intermediary layer between the resin resist and the fluorine-based plasma gas. This protective film allows the plasma gas to etch the target object effectively while preventing direct contact with and degradation of the resin resist, thus maintaining both high etching rate and pattern accuracy
Solution Approach 2:
The protective film is formed in advance before the etching treatment using fluorine-based plasma gas. This preliminary protective coating prevents the resin resist from disappearing during subsequent etching and ashing processes, enabling maintenance of pattern accuracy while achieving high etching rates
2Reliability
If hard mask layer is formed on resin resist layer to prevent resist disappearance, then resist protection is improved, but process complexity and number of apparatuses increase
Solution Approach 1:
The protective function is extracted from the traditional hard mask layer concept and applied directly to the resin resist layer through a specialized protective film formation process. This eliminates the need for separate hard mask layer formation apparatus and simplifies the overall process while maintaining resist protection
Solution Approach 2:
The protective film serves multiple functions: it protects the resin resist from fluorine-based plasma gas and oxygen-based plasma gas, enables high-aspect ratio etching, and maintains pattern accuracy. This multi-functionality reduces the need for additional separate processes and apparatuses
3Manufacturing precision
If multiple apparatuses are used for different treatments, then treatment quality is improved, but substrate contamination and process complexity increase
Solution Approach 1:
Multiple treatments (protective film formation, etching, ashing) are merged into a single apparatus by implementing a multi-step process cycle within one vacuum chamber. This eliminates substrate transfer between apparatuses, preventing contamination while maintaining high treatment quality through the protective film
Solution Approach 2:
The process uses periodic action with repeated cycles of etching treatment and protective film formation. This periodic reinforcement of the protective film during the etching process maintains its integrity and protective function throughout multiple treatment steps, ensuring consistent quality without substrate contamination
4Length of moving object
If repetitive etching steps are performed, then etching depth is improved, but resist layer thickness is reduced and pattern accuracy deteriorates
Solution Approach 1:
The protective film acts as a cushioning layer that absorbs and distributes the harsh conditions of fluorine-based plasma gas during repetitive etching steps. This beforehand protection prevents direct damage to the resin resist, maintaining its thickness and pattern accuracy even after multiple deep etching cycles
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 prevents resist layer reduction and maintains pattern accuracy, reducing process complexity and cost while enabling precise etching of silicon substrates with varied aspect ratios.
Implementation Method 1
a resist protective film-forming step of forming a resist protective film on the resist layer... the resist protective film-forming step uses a plasma film formation method
Implementation Method 2
parts are formed by anisotropic chemical corrosion (attack) using plasma such as a so-called Bosch process
Data Source
AI summary
The present disclosure provides an etching method that includes a resist pattern-forming step of forming a resist layer on a target object, the resist layer being formed of a resin, the resist layer having a resist pattern; an etching step of etching the target object via the resist layer having the resist pattern; and a resist protective film-forming step of forming a resist protective film on the resist layer. The etching step is repetitively carried out multiple times. A processing gas, used in the resist protective film-forming step, includes a gas capable of forming SixOyαz; wherein a is any one of F, Cl, H, and CkHl; and each of x, y, z, k, is a selected non-zero value. After the etching steps are repetitively carried out multiple times, the resist protective film-forming step is performed.