Pulsed Plasma Etching for Semiconductor Micro-Loading Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Plasma etch processes face limitations in etching semiconductor structures with variable spacing, leading to micro-loading issues where etch rates vary with pattern density, resulting in over-etching and detrimental undercutting, especially at small dimensions and high aspect ratios.
Innovation Solution
A pulsed plasma etch method and system are employed, utilizing duty cycles with a short ON state to inhibit micro-loading and a longer OFF state to remove etch by-products, ensuring a consistent etch rate across different density regions, thereby minimizing over-etching and undercutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a plasma etch process is used to etch semiconductor structures with variable spacing, then the etching capability is improved, but micro-loading effects cause etch rate variation with pattern density leading to over-etching and undercutting
Solution Approach 1:
The patent applies periodic pulsed plasma etching cycles with alternating high-power and low-power phases. During high-power phases, aggressive etching occurs; during low-power phases, by-products are removed and micro-loading effects are reduced. This periodic action enables uniform etch rates across varying pattern densities while maintaining high etching capability.
2Reliability
If over-etching is performed to complete etching in high density regions, then all structures are fully etched, but detrimental undercutting occurs in low density regions
Solution Approach 1:
The pulsed plasma process uses periodic cycles where low-power phases allow by-product removal from reaction regions, preventing micro-loading accumulation. This enables uniform etch completion across all density regions without requiring excessive over-etching that would cause undercutting in protected low-density areas.
Solution Approach 2:
The patent dynamically changes plasma power parameters between high and low states during the etching process. High-power phases provide aggressive etching for completion, while low-power phases reduce by-product accumulation and micro-loading effects, preventing undercutting. This parameter modulation achieves both complete etching and damage prevention.
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 pulsed plasma etch process significantly reduces micro-loading effects, allowing for uniform etching of semiconductor structures across varying density regions, reducing the need for over-etching and minimizing structural damage.
Implementation Method 1
A portion of a sample may be removed by applying a pulsed plasma process
Data Source
AI summary
A pulsed plasma system for etching semiconductor structures is described. In one embodiment, a portion of a sample is removed by applying a pulsed plasma process, wherein the pulsed plasma process comprises a plurality of duty cycles. The ON state of a duty cycle is of a duration sufficiently short to substantially inhibit micro-loading in a reaction region adjacent to the sample, while the OFF state of the duty cycle is of a duration sufficiently long to substantially enable removal of a set of etch by-products from the reaction region. In another embodiment, a first portion of a sample is removed by applying a continuous plasma process. The continuous plasma process is then terminated and a second portion of the sample is removed by applying a pulsed plasma process.