Do you know what a semiconductor parameter analyzer is or what it’s used for? Find out how the parameter analyzer first came into being and how it slowly evolved from being an instrument that could measure the I-V characteristics of vacuum tube technology to a modern solid-state semiconductor device. Furthermore, find out why the classic vintage models are popular among lab technicians and what the highest performance parameter analyzer of today is used for.
What Is a Semiconductor Parameter Analyzer?
A semiconductor parameter analyzer also known as a ‘curve tracer’ is a testing device used for the electrical characterization of semiconductor components and devices like diodes, thyristors, and transistors. A parameter analyzer applies voltage and current inputs to the device under test (DUT) and presents the device response on a screen. Device characterization is done by varying one parameter whilst measuring another.
The History of the Semiconductor Parameter Analyzer
The first commercially available parameter analyzer was introduced in 1955 by the Tektronix company, which had been makers of oscilloscopes for nearly a decade at that point. This curve tracer worked by applying a swept voltage to two terminals of the device and then measuring the current that flows through the device. A swept voltage means a voltage that varies with time.
The resulting measurements of current against voltage are presented on the display screen as an I-V graph also known as a current-voltage characteristic curve. The very first model, the Tektronix 570 was originally used for vacuum tube circuits, although as the industry moved to solid-state devices, the parameter analyzers followed suit.
Further development in parameter analyzers eventually led to more advanced testing equipment like the source measure unit (SMU). It is named thus since it is capable of providing a voltage and current source as well as precisely measuring the same parameters. They are available in many forms factors from small bench instruments that look like the classic curve tracers and more sophisticated systems that are used in large-scale production environments.
Measurement Capabilities of a Semiconductor Parameter Analyzer
Semiconductor parameter analyzers usually come in three types, capable of current-voltage (I-V) measurement, capacitance-voltage (C-V) measurement, and pulsed current-voltage (fast I-V) measurements. Most curve tracers can accommodate devices with two or three terminals and have sockets where users can plug in commonly used semiconductor packages.
For devices with two terminals like diodes, the parameter analyzer can display parameters like forward voltage, reverse breakdown voltage, reverse leakage current, and more. For devices that begin to conduct upon reaching the break-over voltage like DIACS, both forward and reverse trigger voltages can be observed as well. For tunnel diodes that have negative resistance properties, their discontinuity can be observed.
Moving into devices with three terminals like transistors and field effect transistors (FETs), parameter analyzers use another connection to the control terminal (base or gate terminal) to conduct device characterization. Since FETs rely on a stepped voltage, the voltage sweeping is done through a configured range of main terminal voltages. A group of I-V curves is generated for each step of the control signal. This allows the user to find the gain of a transistor or the trigger voltage of a thyristor.
Just like (I-V) measurements enable us to determine the leakage and breakdown voltages, capacitance measurements (C-V measurements) and AC Impedance measurements grant us the analysis capability to determine doping concentrations, threshold voltage, and majority carrier concentrations. Furthermore, pulsed I-V characterization can help test high-power devices such as those used in radio frequency applications without exceeding their safe operating limits.
Applications of Semiconductor Parameter Analyzers
Semiconductor parameter analyzers are used today for a variety of applications that range from educational purposes in universities to failure analysis and quality control in semiconductor manufacturing.
Failure Analysis of Semiconductor Devices
Since parameter analyzers allow for the electrical characterization of semiconductor devices, they can be utilized to determine how such a device has failed after use. Failed electronic devices are sent to a lab where an analyst will attempt to isolate the cause of the issue. One of the first steps in this process is electrical failure analysis where a lab technician will test it using a curve tracer. The device’s parameters during operation are compared with its specifications on the data sheet. Any deviation such as abnormal current-voltage graphs will help determine what the next step of analysis will be. For more on how this process works, read Semiconductor Failure Analysis and Why It Is Important.
Parameter Analyzers in Automated Test Equipment
Modern parameter analyzers are much more sophisticated than their older counterparts used bench instruments in a lab. Since the 1980s, they have added functionality like integration with computer systems and are now used in applications that go far beyond simple semiconductor device characterization.
The curve tracer’s modern counterpart is called the ‘source measure unit’ which is a rack-mounted system used in production environments. Some are integrated into automated test equipment (ATEs) which semiconductor device manufacturers use to screen their products for quality control. This testing has to be done at a massive scale to keep up with the demand. ATEs have all the test capabilities of parameter analyzers but also precise control systems to handle the devices and software programs to run the various testing signals. For more on this, read Semiconductor Chip Testing Using Automated Test Equipment.
Educational Purposes
Parameter analyzers are used in electrical engineering classrooms at universities around the world. They provide students the chance to observe in real-time the characteristics of devices like transistors and diodes. These curve tracers are also simple to use and allow students to apply their theoretical knowledge in a safe lab environment.
Classic Parameter Analyzers Are Still Here
While newer models of parameter analyzers have been developed over the decades, some labs and universities are still using the earlier models due to their relative simplicity in operation. The user experience is not complicated, with turning knobs to adjust the input signals and observing the results on the screen. There is even a second-hand market for vintage instruments due to this demand. The downside of relying on vintage models is that maintaining them and finding replacement components in case of breakdown can be difficult.
The result is that manufacturers introduced new parameter analyzer units that are equipped with modern touchscreen displays and other improvements like data-export capabilities but with the simple usability of a classic model. They are also smaller and more portable than older models and easily fit on a test bench unlike the ones used in production environments. Whether they’re providing I-V curves or capacitance measurements, at the university or fabrication plant, the semiconductor parameter analyzer is here to stay.
FAQs
A semiconductor parameter analyzer also known as a ‘curve tracer’ is a testing instrument used to measure current-voltage and capacitance measurements of semiconductor devices such as diodes and transistors.
A semiconductor parameter analyzer is used for the electrical characterization of semiconductor devices which is useful for failure analysis, quality control in semiconductor manufacturing, and education purposes.
Curve tracers are similar to oscilloscopes and work by varying one parameter while measuring the response of another.
