Cyclic Etching and Annealing for Semiconductor Material Layer Removal
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Solution Overview
Problem
The miniaturization of devices leads to challenges in dry etching processes, where by-products remain in small gaps, causing incomplete etching and loading effects due to the difficulty in completely removing material layers, especially in high aspect ratio structures.
Innovation Solution
A cycle process is repeated multiple times, combining etching and annealing steps with specific gas compositions and temperature controls to effectively remove material layers and reduce loading effects, including the use of NF3 and NH3 for etching and H2 and Ar for annealing, with optional pre-annealing and purging processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry etching is used to achieve vertical structure and precise etching, then etching control and precision are improved, but by-products remain in small gaps causing loading effect
Solution Approach 1:
The patent implements a cyclic etching-annealing process where dry etching is periodically alternated with annealing treatments. After each etching step that removes material layer, an annealing step is performed to thermally decompose and remove accumulated by-products from small gaps. This periodic repetition continues for multiple cycles until the desired etching depth is achieved, preventing loading effect while maintaining vertical structure precision.
Solution Approach 2:
The patent converts the harmful by-products generated during dry etching into removable volatile compounds through annealing treatment. The annealing process thermally decomposes the by-products (such as polymer residues) into volatile substances that can be evacuated, transforming the loading effect problem into a可控 (controllable) removal process that actually improves etching uniformity.
2Manufacturing precision
If wet etching is used to achieve high etching selectivity, then selectivity is improved, but vertical structure cannot be obtained
Solution Approach 1:
The patent merges the advantages of both wet and dry etching by combining them in a sequential process. Dry etching is first used to achieve the vertical sidewall structure and precise dimensional control, followed by wet etching steps that provide high selectivity for removing specific material layers. The combination allows both vertical structure formation and high selectivity to be achieved.
Solution Approach 2:
The patent introduces an intermediate annealing process between dry etching steps that acts as a mediator to remove by-products and prepare the surface for subsequent wet etching. This intermediate treatment facilitates the transition between dry and wet etching modes, enabling both processes to work synergistically without interference.
3Productivity
If device size is miniaturized to increase integration, then device density is improved, but by-products accumulate in small gaps
Solution Approach 1:
The patent applies periodic annealing treatments between etching steps to continuously remove by-products that accumulate during miniaturized device fabrication. The cyclic process ensures that even in extremely small gaps between miniaturized devices, by-products are periodically cleared, maintaining etching effectiveness throughout the high-density device array.
Solution Approach 2:
The patent performs preliminary annealing treatments before final etching steps to pre-clear by-products from small gaps. This preliminary action prevents by-product accumulation from affecting the precision of subsequent etching operations on miniaturized devices, ensuring clean etching surfaces throughout the high-density structure.
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 ensures complete removal of material layers, reducing by-product residues and loading effects, even in small gaps, thereby improving etching precision and efficiency in semiconductor processes like FinFET STI and replacement metal gate processes.
Implementation Method 1
performing an etching process to remove a portion of the material layer, wherein an etching gas of the etching process includes NF3 and NH3
Implementation Method 2
performing an annealing process to remove a by-product generated by the etching process, wherein a temperature of the annealing process is from 150° C. to 500
Implementation Method 3
A removing method including the following steps. A substrate is transferred into an etching machine
Data Source
AI summary
A removing method including the following steps. A substrate is transferred into an etching machine, wherein the substrate has a material layer formed thereon. A cycle process is performed. The cycle process includes performing an etching process to remove a portion of the material layer, and performing an annealing process to remove a by-product generated by the etching process. The cycle process is repeated at least one time. The substrate is transferred out of the etching machine. In the removing method of the invention, the cycle process is performed multiple times to effectively remove the undesired thickness of the material layer and reduce the loading effect.