Dual RF Transmission Layout for Uniform Plasma Etching
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Solution Overview
Problem
Existing plasma processing systems face challenges in achieving uniform plasma distribution within the plasma chamber, leading to non-uniform etch rates and issues like the center hotspot phenomenon, where the etch rate is higher at the center of the wafer and lower at the edges, causing problems such as punching, not open, and clogging.
Innovation Solution
A plasma control apparatus with a first transmission line for main RF power and a second transmission line for auxiliary RF power, where the auxiliary RF power is used to cancel out harmonics sensed in the plasma chamber, ensuring uniform plasma distribution by applying main RF power to the center and auxiliary RF power to the edges, utilizing a matching circuit for impedance adjustment and plasma control circuits to selectively control harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If main RF power is applied to the plasma chamber through a single transmission line, then the plasma process can be performed, but non-uniform plasma distribution occurs leading to center hotspot phenomenon
Solution Approach 1:
The single transmission line is segmented into two separate transmission lines: a first transmission line for delivering main RF power and a second transmission line for delivering auxiliary RF power. This segmentation allows independent control of power distribution to different regions of the plasma chamber, enabling uniform plasma distribution by compensating for the center hotspot phenomenon through the auxiliary RF power applied to the edge region.
2Adaptability or versatility
If RF power is transferred through at least two frequencies, then plasma control capability is improved, but device complexity increases due to multiple transmission lines and control circuits
Solution Approach 1:
The first and second transmission lines share common components including the plasma chamber, matching circuit, and sensor system. The auxiliary RF power source and its control circuit work in conjunction with the main RF power system rather than as completely separate systems. This multi-functionality approach enables enhanced plasma control capability through dual-frequency operation while minimizing the increase in device complexity by utilizing shared infrastructure.
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 effectively alleviates the center hotspot phenomenon by reducing etch rates at the center and increasing them at the edges, resulting in more uniform etch rates across the wafer, thereby improving plasma processing outcomes.
Implementation Method 1
an auxiliary RF power source connected to the second transmission line and configured to generate auxiliary RF power to cancel out the harmonics sensed by the sensor
Implementation Method 2
a matching circuit connected to the first transmission line and configured to adjust impedance to increase power transmission of the main RF power
Implementation Method 3
a first plasma control circuit connected to the first transmission line and configured to selectively and independently control harmonics of one or more of the at least two frequencies of the main RF power
Data Source
AI summary
A plasma control apparatus includes a first transmission line and a second transmission line transferring radio frequency (RF) power to a plasma chamber, a matcher disposed on the first transmission line a first plasma control circuit disposed on the first transmission line and configured to selectively and independently control harmonics of one or more of the at least two frequencies, a sensor configured to sense the harmonics of the plasma chamber, and an auxiliary RF power source disposed on the second transmission line and configured to generate auxiliary RF power to cancel out the harmonics sensed by the sensor, wherein, in a plan view, the first transmission line transfers the RF power adjacent to the center of the plasma chamber, and the second transmission line transfers the RF power and the auxiliary RF power and the auxiliary RF power adjacent to an edge of the plasma chamber.