Semiconductor Wafer Etching with HF-Ozone Gas Monitoring
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Solution Overview
Problem
Current etching methods for semiconductor wafers, particularly those using hydrogen fluoride and ozone, face challenges in monitoring the etching depth and surface uniformity, leading to difficulties in achieving precise control and feedback during the etching process, especially in wet conditions, which can result in overpolishing or overetching.
Innovation Solution
An etching method and apparatus that jets a mixed gas of hydrogen fluoride and ozone onto a semiconductor wafer surface, equipped with a monitoring device to track the surface conditions, allowing for real-time regulation of either or both hydrogen fluoride and ozone concentrations to maintain precise control over the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a mixed gas of hydrogen fluoride and ozone is used for etching in wet conditions, then the etching process can be performed, but real-time monitoring of etching depth and surface uniformity becomes difficult
Solution Approach 1:
The patent changes the physical state parameter of the etching environment from wet to dry by using a mixed gas of hydrogen fluoride and ozone. This parameter change enables optical monitoring methods to function effectively, as the dry gas environment allows light to pass through and reflect off the wafer surface without interference from liquid medium, thereby enabling real-time measurement of etching depth and surface uniformity.
Solution Approach 2:
The patent introduces an optical monitoring system as an intermediary between the etching process and the control system. This intermediary enables indirect measurement of etching depth by detecting optical properties (such as reflectivity or interference patterns) that change as the etching progresses, allowing real-time feedback without direct physical contact with the wet etching environment.
2Productivity
If conventional wet etching methods are used, then the etching process can proceed, but feedback control during the process cannot be realized
Solution Approach 1:
The patent implements a feedback control system where an optical monitoring device continuously measures the etching progress in real-time, and this measurement information is fed back to the control system. The control system then adjusts etching parameters (such as gas flow rate or power) dynamically to maintain the desired etching rate and achieve the target depth, enabling automated feedback control during the etching process.
Solution Approach 2:
The patent ensures continuous monitoring and control throughout the etching process by maintaining the dry gas environment and continuous optical measurement. This continuous action allows the feedback loop to operate without interruption, enabling real-time adjustments rather than post-process measurement and correction.
3Measurement precision
If additional apparatuses such as vacuum chamber and plasma generator are used for dry etching, then film thickness measurement becomes easier, but the facility scale increases
Solution Approach 1:
The patent makes the optical monitoring system multi-functional by designing it to work in the specific dry gas etching environment created by the hydrogen fluoride and ozone mixed gas. The same optical system serves both as a process monitor and as a thickness measurement device, eliminating the need for separate vacuum chambers or plasma generators that would be required for traditional dry etching methods.
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 enables precise control over the etching process, ensuring in-plane uniformity and preventing overpolishing or overetching by allowing for real-time adjustments based on surface monitoring, thereby improving the accuracy and efficiency of the etching process.
Implementation Method 1
a mixed gas that contains hydrogen fluoride and ozone is jetted onto a semiconductor wafer surface
Implementation Method 2
the semiconductor wafer surface is monitored
Data Source
AI summary
A method and an apparatus of etching a semiconductor wafer are provided. The etching apparatus of a semiconductor wafer having a marker inside includes: a monitoring device capable of monitoring a surface of the semiconductor wafer so as to detect the marker; a nozzle capable of jetting a mixed gas that contains hydrogen fluoride and ozone onto the surface of the semiconductor wafer; a regulator capable of adjusting at least one of hydrogen fluoride concentration and ozone concentration in the mixed gas; and a controller capable of determining whether the marker is detected by the monitoring device and terminating the etching process.