Macro of Silicon Wafers

Wafer-Handler Motion Control System: CAPS

Authors

Josh West – FormFactor

Tristan Debrunner – FormFactor

Cherry Durfee – Solubit 

Sarah Morales – Solubit

The Challenge

To develop a seamless, integrated motion control system from disparate hardware and software components. The overall goal of the system is to better accommodate behavioral changes in materials during cryogenic temperature cycles.

The Solution

A LabVIEW™ based application developed to allow direct control and automated testing based on customer needs. The application communicates with motion control and vision software tools, provided by semiconductor testing experts. LabVIEW™ controls hardware components, including power supplies, pumps, and valves. This equipment monitors temperature, pressure, magnetic field, and flow from multiple sensors and instruments. 

Integration with the wafer loading system has reduced exchange times from 20-25 minutes to 8-9 minutes. System errors are handled robustly during cryogenic temperature cycling and wafer probing, reducing downtime for the system. 

Solubit’s GMOD libraries are the basis for this highly modular test framework that provides a user-friendly interface with test sequencing prompts for operators.

Silicon wafer in die semiconductor wafer handling machine

Reduced exchange times by 60%

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About FormFactor

FormFactor partners with technology leaders to optimize device performance, advance yield knowledge, and improve product output. Their collaborations extend from the application development and pre-production phase, to design and volume manufacturing. 

By taking advantage of their expertise, solutions, and infrastructure, their customers can drive continuous innovation with greater control and fewer economic risks. Collaborating with FormFactor to protect and enhance performance and device yield, developers, designers, and manufacturers of next-generation devices can accelerate their time-to-market and their profitability. 

Wafer-scale Cryogenic Systems

The HPD Cryogenic wafer-scale Probe Stations tackle problems like long turnaround times, high noise, and low signal capabilities. By employing world-class technology and superior cryogenic probing knowledge, these systems enable accurate measurements at cryogenic temperatures.

Key Motion Control Application Features

This application is a prime example of the power and flexibility of LabVIEW™. The development of this application leaned on LabVIEW™ to pull together four disparate control software packages to provide a tool for the user to control or monitor the system from one main User Interface.   

Solubit’s GMOD library was heavily utilized in developing the system framework to establish test sequence modules that are easy to manage, scale, and update as needed. The GMOD libraries were also used to communicate with hardware, log data, handle system errors, and monitor system safety. 

The overall success of this application can be summarized as volume wafer loading with a realized higher throughput.

Benefits of Solubit GMOD Libraries

This highly modular test system relies on the customizable nature of Solubit’s GMOD libraries and their ability to communicate with various software processes. The GMOD libraries are a versatile framework built in-house by Solubit developers to better meet the needs of our customers.

One example of the modularity provided by Solubit’s GMOD libraries is sequencing. Based on user input a message is sent to the Sequencer. The Sequencer enqueues the corresponding steps associated with the request and sends them to the Worker. The Worker performs steps such as prompting the user for required inputs and messaging other modules to control hardware as needed. The messages sent directly from the Worker to hardware modules are the same messages that are sent by the User Interface for direct control. 

GMOD pairs well with LabVIEW™ to build a more intuitive UI front panel that has high-level action options, such as “Start Cooldown” and “Start Testing”, as well as low-level action options, such as “Set Pressure”. Subpanels load multiple UIs into the Main Executive UI. Each subpanel is the Main VI of a GMOD, which controls a different component of the system, for example, the Vacuum Module and the Temperature Module. Each module has its own configuration that contains various settings such as hardware details, safety limits, automated testing values, and more depending on the module’s functions.  

Within the system’s settings, a user can change and save the configurations which are loaded at the start of the application. This makes it easy to implement new system versions and updates, without rewriting past system configurations and processes.

ScreenShot of LabVIEW code sequence from Solubit's GMOD Libraries
The GMOD libraries are a versatile framework built in-house by Solubit developers to better meet the needs of our customers.

Solubit’s GMOD Libraries build a modular foundation for any system.

Realizing Higher Throughput

Solubit supported FormFactor in realizing higher throughput by integrating motion control software into a modular architecture and by automating the wafer testing processes. 

The wafer cassette loaders on this cryogenic probing station have a 25-wafer capacity. Solubit’s development provides seamless communication with the motion control software to reduce exchange times by 60%.  

This success was realized through improved system monitoring and error handling. As material behaviors change at cryogenic temperatures, system freezes are slowing throughput and establishing time delays. System error impact was reduced with action, operation, and testing sequence governance built into the application. 

When a lapse in communication occurs, a configurable safety limit is crossed, or the system is not in the correct state, the system will pause and notify the user of the error and provide options for how to proceed (i.e. retry or ignore). Therefore, the system no longer experiences time-costing freezes but handles errors and warnings properly. 

FormFactor
FormFactor

FormFactor, Inc. is a leading provider of essential test and measurement technologies along the full IC life cycle – from characterization, modeling, reliability, and design de-bug, to qualification and production test.