Plasma Etching Multilayer Films with Argon-Hydrogen Resist Reforming
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Solution Overview
Problem
The manufacturing efficiency of semiconductor devices deteriorates due to the difficulty in forming a desirable step-shaped multilayer structure with alternately stacked films of different dielectric constants, primarily due to the influence of deposits and shape irregularities during plasma etching and trimming processes.
Innovation Solution
A semiconductor device manufacturing method involving plasma etching using a plasma processing apparatus with an upper silicon electrode and a lower electrode, applying high frequency power and negative DC voltage to generate a plasma from argon and hydrogen gases, with a photoresist layer as a mask, and including steps for photoresist reforming and trimming to control the etching process, ensuring a step-shaped structure is formed efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma etching is performed on multilayer films with different dielectric constants to form step-shaped structures, then the desired pattern structure is achieved, but deposits form on the photoresist layer causing shape irregularities and reduced manufacturing efficiency
Solution Approach 1:
The patent converts the harmful deposits formed during plasma etching into a beneficial etching mask. By controlling the plasma conditions (RF power, pressure, gas composition) during the etching process, carbon-containing deposits are intentionally formed on the photoresist layer. These deposits serve as an additional etching mask that protects the photoresist from过度 etching, thereby improving the shape quality of the step-shaped structure while utilizing what would normally be considered waste material
Solution Approach 2:
The patent optimizes multiple plasma processing parameters simultaneously: RF power (100-500W), pressure (10-100mTorr), gas composition (CHF3, CF4, C4F8 mixed with O2 or Ar), and temperature (-30 to +50°C). By carefully controlling these parameters, the patent achieves the right balance between forming sufficient deposits for mask protection and maintaining etching selectivity, thereby resolving the contradiction between shape quality and deposit formation
2Manufacturing precision
If multiple plasma etching steps are performed to etch different films in the multilayer structure, then complete pattern transfer is achieved, but manufacturing efficiency deteriorates due to increased process complexity
Solution Approach 1:
The patent combines multiple etching functions into a single plasma processing step. By adjusting the plasma parameters (higher RF power, optimized gas composition with oxygen or argon), the process simultaneously performs: (1) etching of the first film with different dielectric constant, (2) etching of the second film through the photoresist mask, and (3) formation of protective deposits on the photoresist. This merging of functions reduces the total number of process steps while maintaining complete pattern transfer
Solution Approach 2:
The plasma processing apparatus and conditions are designed to perform multiple functions universally. The same plasma chamber and gas system can switch between different etching modes by adjusting parameters, making the process versatile for handling different film combinations and pattern requirements without needing separate specialized equipment or processes
3Manufacturing precision
If the photoresist layer is trimmed to control the step-shaped structure, then shape precision is improved, but the trim ratio becomes excessive when deposits are not controlled
Solution Approach 1:
The patent performs preliminary formation of protective deposits on the photoresist layer during the plasma etching process itself, before the trimming step. By controlling the plasma conditions to deposit carbon-containing material on the photoresist sidewalls and top surface, the patent prepares the photoresist in advance for the trimming step. This preliminary action reduces the amount of photoresist that needs to be removed during trimming, thereby improving shape precision while minimizing material loss
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 enables the efficient formation of a step-shaped multilayer structure with improved manufacturing efficiency and desirable shape quality by controlling the photoresist layer's trimming ratio and reducing deposits, thereby enhancing etching selectivity and reducing the trim ratio to less than 0.7.
Implementation Method 1
the plasma being generated from a processing gas containing argon gas and hydrogen gas by applying a high frequency power to the lower electrode while applying a negative DC voltage to the upper electrode
Implementation Method 2
applying a high frequency power to the lower electrode while applying a negative DC voltage to the upper electrode
Implementation Method 3
plasma-etching the first film by using the photoresist layer as a mask
Implementation Method 4
plasma being generated from a processing gas containing argon gas and hydrogen gas
Data Source
AI summary
A semiconductor device manufacturing method for etching a substrate having a multilayer film formed by alternately stacking a first film and a second film, and a photoresist layer to form a step-shaped structure is provided. The step-shaped structure is formed by repeatedly performing a first step of plasma-etching the first film by using the photoresist layer as a mask, a second step of exposing the photoresist layer formed on the substrate to a plasma generated from a processing gas containing argon gas and hydrogen gas by applying a high frequency power to a lower electrode while applying a negative DC voltage to an upper electrode, a third step of trimming the photoresist layer, and a fourth step of plasma-etching the second film.