Wafer test

The wafer test is a functional test in the manufacturing process for the production of integrated circuits .

description

It is carried out on the not yet divided wafer in order to identify faulty circuits at an early stage. To do this, the wafer is placed in a test device, the wafer prober, in which contact needles establish a connection to the test pads of the individual circuit. Faulty circuits are marked in color and sorted out after the wafer has been sawed.

The difficulty with wafer testing is contacting the circuits with small pin-shaped contacts. For this, the automatic test system ( Automatic Test Equipment ) requires many contact needles that are arranged on a needle card.

In order to achieve this, fine rigid needle adapters can be used, in which the rigid needles are deflected from the desired contacting position onto a spring pin , which then forwards the measurement signal to the electronics. With today's rigid needle adapters , 60 to 70 µm large test areas can be contacted with a distance of 150 µm. If the spring pins are arranged in a 0.6 mm grid, 280 test points can be contacted on one square centimeter.

A new trend is the replacement of the contact needles with miniaturized springs ( micro springs ) or MEMS , i.e. structures produced by photolithography processes, thin-film processes and etching. This enables contact distances of less than 40 µm. Components with multiple micro springs can be mounted on a base plate in a similar way to integrated circuits .

literature

• Fundamentals of Digital Semiconductor Testing (Version 4.0) by Guy A. Perry (Spiral-bound - Mar 1, 2003). ISBN 978-0965879705
• Principles of Semiconductor Network Testing (Test & Measurement) (Hardcover) by Amir Afshar, 1995, ISBN 978-0-7506-9472-8
• Power-Constrained Testing of VLSI Circuits. A Guide to the IEEE 1149.4 Test Standard (Frontiers in Electronic Testing) by Nicola Nicolici and Bashir M. Al-Hashimi (Kindle Edition - Feb 28, 2003), ISBN 978-0-306-48731-6
• Semiconductor Memories: Technology, Testing, and Reliability by Ashok K. Sharma (Hardcover - Sep 9, 2002), ISBN 978-0780310001

Individual evidence

1. ↑ Michael Orshansky, Sani Nassif, Duane Boning: Design for Manufacturability and Statistical Design: A Constructive Approach . Springer Science & Business Media, 2007, ISBN 978-0-387-69011-7 ( google.de [accessed November 10, 2018]).