Most of us know that a real arc can disrupt our process and chamber parts which results in a measureable loss.
But do you know the impact of micro arcs and the influence on your process?
How could you measure micro arcs? Which solutions exist on the market?
Process control in semiconductor manufacturing has emerged as a crucial factor for cost-effective semiconductor manufacturing. Early era of process control focused on process and tool monitoring and optimization, and it moved to process and tool monitoring which may include health of the tool, health of the process, and health of the line monitoring. Recently, advanced process control (APC) with advanced sensors was suggested for the detection of abnormal plasma process condition.
Advanced sensors employed for plasma process monitoring are probe type sensors to measure electron temperature and density through plasma potential, RF sensor to measure plasma impedance, and optical emission spectrum (OES) to measure plasma chemistry inside the process chamber.
Probe type sensors provide much of quantitative measures for plasma characteristics, but it suffers from plasma perturbation. RF sensors are useful for the monitoring of plasma impedance with high data acquisition frequency, but it requires room for hardware installation and sometimes it causes influence to the process. Optical emission spectroscopy (OES) provides the information of ionized gas species resides inside the chamber with the easiness of hardware installation, but the data acquisition speed is limited to 10 msec (0.1kHz).
To overcome the disadvantages of aforementioned advanced sensors, we propose high-speed optical plasma monitoring system the commercial name is “PAMS (Plasma Arc Monitoring System)” with the application of the detection of abnormal discharge monitoring which provides up to 250 kHz sampling speed in order to detect any disturbance in plasma.
What is the ARC during the plasma process?
▶ARC is an abnormal discharge which can be occurred on the wafer, chamber parts, or bulk plasma itself during the plasma process.
▶ARC has the secondary discharge phenomena which can cause light emission.
▶Even though without light emission, incident instability of the plasma is also can be called as an ARC.
▶ARC can cause damage to product directly, or not.
Abnormal Discharge and Plasma ARC are important issues in current semiconductor manufacturing
Abnormal discharge of plasma may generate particles and leave scratch marks on the wafer, lowering the processing yield.
Furthermore, it may also damage parts resulting in a noticeable increase in equipment down time for maintenance.
Also referred to as spark, anomalous discharge, anomalous ARC, and plasma ARC, this phenomenon occurs spontaneously within a very short period.
One of the most significant abnormal plasma discharges is defined as ARC which causes unstable plasma.
It has been observed that a noticeable ARC is often followed by a sudden voltage drop and large amount of induced current in the plasma.
When the ARC hits the chamber wall or parts, it generates extraneous particles of deposited material inside the chamber.
ARC can be produced when the plasma fails to maintain symmetric confinement with the sheath, and it is different from plasma oscillation or fluctuation.
Especially, as the process technology develops remarkably, micro-arcing also has become an important issue in current semiconductor manufacturing.
Whenever we analyze the PAMS raw data, there are several data patterns.
To do easy communication between PAMS users, we made several categories.
These categories can help PAMS users to share the plasma status without mistake
▶Spiking : Within very short term, intensity changes one or more times.
▶Fluctuation : Plasma move without frequency. Very irregular movement.
▶Oscillation : Plasma move with frequency.
▶Transition : During steady state process, frequency and amplitude are changed.
Thanks our great Partner DJ Chang and Dr. Lee our we are able to offer this fast Plamsa Monitoring system to our customers.
We welcome you to discuss this topic further with you. Contact me at email@example.com