Customer Success Stories


NASDAQ 100 Technology Company Reduces Production Costs Using the Octiv RF Sensing Platform





NASDAQ 100
Chip Maker


70% Reduction
In Maintenance Costs


10% Increase
In Production Throughput


>Hours
Of Product Scrap Prevented Per Fault


>1000%
Return On Investment Per Year


>$1M
Projected saving in maintenance and scrap reduction per tool per annum

Directly attributed to the integration of the Octiv sensing platform


The Challenge

Needing to improve the performance, and extend the lifetime, of an aging fleet of plasma etching tools, this long-time Impedans client sought a solution with the following requirements:


• Monitor the vital-signs of each plasma etching tool
• Determine the health of the RF power delivery subsystem
• Identify if the substrate was properly positioned by the robotic arm
• Communicate data seamlessly to the factory host
• Prevent product scrappage and reduce maintenance costs


The Solution

The Octiv RF sensor was integrated in the etching tool RF path, at the output of the matching network. The key RF parameters were measured and streamed over the network to the factory host. Data was recorded, time-stamped and stored in the customer’s data base along with the tool context data. The data captured during fault events were later analysed. Correlations between RF data and fault conditions were established. Control limits were then applied to relevant parameters, excursions from which are used to indicate faults and initiate corrective action.


The Process

Impedans’ RF and mechanical design teams identified the optimum location for Octiv RF sensor installation. A custom sensor form factor was designed. A first unit was then manufactured and installed. Data was captured while the tool was in production over a predefined period. Product was inspected off line in the usual way. The time stamps for defective products were correlated with RF data from Octiv. Impedans experts analysed and modelled the RF data and identified fault signatures. Corrective action procedures were implemented based on Impedans recommendations. Impedans software experts worked closely with the customer’s software team to implement a simple, robust Ethernet protocol to communicate sensor data to the factory host. Once the first few product scrap events were prevented, roll out across the entire fleet was initiated.


Achievements

RF Power Subsystem Health Verification
The first problem to be solved was product scrappage due to stress in the power delivery subsystem. Impedans experts discovered that certain plasma etch processes were operating at the edge of the matching unit’s impedance range. This caused the matching unit to become unstable, occasionally. The RF data collected by the Octiv sensor was used to identify the onset of this unstable mode. The problem was solved by restarting the process.


Substrate Misplacement
Substrate misplacement on the electrostatic chuck, due to component wear and tear, was periodically leading to wafer scrappage. This fault was undetectable from the pre-existing tool feedback i.e. forward and reflected power showed no error. Thus, several hours of scrappage could go undetected. Octiv provided a clear signature of the substrate misplacement fault enabling corrective action to be taken.


Reduced Maintenance Time
Due to the reliability of the RF data provided by Octiv, test wafer qualifications were reduced by 70%, enabling higher throughput of production wafers.


Multinational Medical Device Companies Turn to Plasma Measurement to Improve Process Yield





Multinational
Medical Device Companies


Increased
Throughput


Improved
Process Performance


Outsourced
RF & Plasma Expertise


Return on Investment
Far Exceeds Installation Costs


Critical Process
Problems Solved


The Challenge

Plasma processing is used extensively in medical device manufacturing. Applications include the modification of surfaces (to improve adhesion or reduce friction), sterilization and bio-compatible coatings for implants. Impedans have assisted several multinational medical device manufacturers to implement plasma measurement solutions to improve process performance and reduce product scrap. We have developed several applications to detect RF related issues, such as arcing and equipment malfunction, which lead to poor tool performance and reduction in product yield. The main applications can be summarised as follows:


• Direct ion current measurement to detect plasma ignition failure at intervals through a 50 Hz power cycle, in processes used for catheter treatment
• RF matching unit tracking at millisecond report rates for sub-second RF sterilization processes
• Identify if the substrate was properly positioned by the robotic arm
• Direct ion energy measurements on multiple shelves (simultaneously) in stent and catheter plasma processing chambers
• RF impedance monitoring and arc detection for process monitoring of plasma chambers used for treating various in-vitro medical devices.


The Solution

A custom Langmuir probe design and algorithm was developed for a 50 Hz ignition failure application. The Langmuir probe was installed in place of the catheter and the measurements clearly showed periods when the plasma did not strike, leading to unprocessed regions of the catheter. These measurements enabled the customer to fine tune the equipment and solve the issue. The Octiv RF sensing platform was ideal for millisecond tracking of the matching network in the RF sterilization process. The customer also made use of the industrial EtherNet/IP protocol for process monitoring. A custom Semion (retarding field energy analyzer) was developed for a multi-shelf plasma processing chamber application. This system highlighted that plasma was failing to ignite between some shelves leading to stent/catheter scrap. The customer used this data to track the source of the problem and improve tool performance. The Octiv RF platform and Alfven event detector platform were used to monitor plasma impedance and RF arcs in a process used for in-vitro medical device processing. This provided the customer with invaluable data for their process monitoring and control applications.


The Process

Impedans’ development team works with the customer to find the optimum plasma sensing solution for their application. A custom sensing solution is developed. The sensor is manufactured and installed. Impedans’ software team work in tandem with the company’s IT team to identify the optimum solution for data management if necessary. Data is captured for a range of experimental conditions. Impedans plasma team collaborate with Impedans experts to analyse the data and identify fault signatures. Corrective action procedures are developed in collaboration with Impedans experts. The customer can avail of the Impedans Protect support packages to maintain the accuracy of the custom sensing platform long into the future.


Achievements

Smart Sensing and Data Management
Medical device customers utilise the enormous pool of plasma and RF expertise built up by Impedans over many years to tackle their plasma processing issues. Sensing and data management systems are tailored to the needs of the medical device customer. In all cases the return on investment far exceeded the cost of implementation. As medical device processing becomes more complex and production volumes are ramped up, smart sensing and data management capabilities are crucial requirements.



Pulsed RF Plasma Monitoring | Critical at 7nm Node
Alfven | 100 Event Detector



The Background

In recent years pulsed RF plasma processes have been shown to improve etch selectivity, increase etch anisotropy and reduce feature damage in the semiconductor industry. The reasons for this are (a) different plasma chemistry sets can be accessed compared to continuous wave plasmas and (b) greater control on the ion impact energy can be achieved. The move to pulsed operation has created a strong need for accurate pulsed RF sensing technology. Pulsed RF plasma process monitoring is critical as the industry moves to the 7nm node and beyond.

Impedans are leading the way in RF plasma process monitoring with the most advanced Voltage/Current (VI) probe technology on the market. This versatile instrument can be used as a general VI probe or it can be programmed for specific applications. Here, we discuss an application developed for pulsed RF plasma monitoring to meet the needs of the semiconductor manufacturing industry.


The Challenge

Semiconductor fabrication facilities around the globe are gearing up to manufacture integrated circuits at 7 nm and 5 nm nodes to meet the needs of the next generation of consumer electronics. Pulsed RF plasmas are a key part of the manufacturing process. The most common carrier frequency is 13.56 MHz, other common frequencies include 2 MHz and 60 MHz. Pulse frequencies tend be in the range of 10 Hz – 10 kHz. The pulse modulation shape tends to be square, modulation depth can be 100% or have multiple step levels and the duty cycle can be as low as a few percent. Multiple RF frequencies can be used at the same time, one or all pulsing, and to complicate things even further the RF carrier frequencies may not be constant – carrier frequency tuning of the order of ± 10% is common. This presents a significant challenge to RF sensing technologies. Semiconductor manufacturers have several key monitoring requirements for this type of process including;


• Carrier frequency monitoring of voltage and current during the pulse
• Frequency tracking to report accurate voltage and current levels during frequency tuning
• pulse characteristics such as; duty cycle, pulse frequency, pulse rise/fall time
• Individual pulse logging (microsecond resolution) capability for diagnostic purposes.


The Solution

Impedans have developed the Alfven | 100TM RF Event Detector to capture short lived RF events, such as RF pulses. The Alfven product runs on Impedans’ cutting edge VI probe platform. A standard VI probe captures blocks of data and carries out fast Fourier transforms to analyse the frequency spectrum. This complex procedure creates a bottleneck in terms of data capture speeds.

For the Alfven application, the firmware is reconfigured to incorporate an amplitude detection algorithm. This allows voltage and current data to be captured continuously with 1 μs time resolution. The amplitude detector is designed to detect the amplitude of the fundamental frequency ± 10%. To avoid excessive data generation the Aflven is generally operated in an ‘exception’ based mode i.e. the customer specifies the ‘normal’ pulse characteristics and the Alfven only logs detailed pulse profiles for pulses that are not accepted as ‘normal’. A 5 ms record length, with 1 μs resolution is stored for each non-standard pulse. Additionally, pulse characteristics (including duty cycle and frequency) are reported at 10 samples per second, where each reported parameter is an average over 100 ms.

The Alfven also has a diagnostic mode, where every pulse can be configured as an event and thus recorded, for a limited time duration. For a 25 second process, with pulse frequency of 200 Hz, the Alfven will capture 5,000 individual pulses each with 5 ms record length and 1 μs resolution. The full profiles can be stored and saved to a PC or the important pulse characteristics can be calculated and stored, so that the full profiles can be discarded, limiting the amount of data that needs to be handled.

The Alfven is designed to be mounted in-line between the RF generator and the matching network. Each sensor is optimised for a single fundamental carrier frequency and does not suffer interference for another carrier frequency if present. The Alfven is used for pulse monitoring applications by semiconductor manufacturers and equipment makers. Alarms are implemented for pulsed processes that run outside the acceptable limits, preventing wafer scrappage and improving product throughput.