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Diode Production Test Using the
Agilent B2900A Series of SMUs
Technical Overview

Agilent B2901/02/11/12A Precision Source/Measure Unit
Agilent B2901A Precision SMU, 1ch, 100 fA resolution, 210 V, 3A DC/10.5 A pulse
Agilent B2902A Precision SMU, 2ch, 100 fA resolution, 210 V, 3A DC/10.5 A pulse
Agilent B2911A Precision SMU, 1ch, 10 fA resolution, 210 V, 3A DC/10.5 A pulse
Agilent B2912A Precision SMU, 2ch, 10 fA resolution, 210 V, 3A DC/10.5 A pulse

Introduction source and measure both voltage
and current. They cover currents
To ensure compliance with manu- from 10 fA to 3 A (DC)/10.5 A (pulse)
facturing specifications, single-point and voltages from 100 nV to 210 V.
pass/fail DC testing must be per- In addition to these comprehensive
formed on packaged diodes. Because measurement capabilities, the
these tests are also used to identify B2900A Series of SMUs possesses
and remove defective devices before high throughput that reduces test
shipment, their reliability is important times. The B2900A Series of SMUs
to guarantee product quality. In addi- also has many features that make it
tion, it is also essential to perform the well-adapted for production test, such
tests quickly to keep the production as pass/fail binning, a digital I/O
throughput high. interface for handler control, and code
compatibility with standard single and
Agilent B2901/02/11/12A Precision dual channel SMU products.
Source/Measure Unit meets all of
these requirements, making it the This technical overview shows how
best solution for diode production to use the B2900A Series of SMUs for
test. It is a compact and cost- production test. A simple diode test
effective bench-top Source/Measure example will be shown for a forward
Unit (SMU) with the capability to voltage test (VF).
Easy production test Program memory For tests that utilize lots of repeated
code (such as subroutines), program
system configuration improves throughput memory can dramatically reduce test
Figure 1 shows a conceptual diagram Fast test times are essential to times. Of course, programs can be
of a system based on the B2900A maximize throughput and maintain saved to or loaded from any attached
Series of SMUs for production diode high levels of factory productivity. USB flash memory device (please see
test. The widely available banana Besides possessing fast intrinsic Figure 2).
style terminals of the B2900A Series measurement speed, the B2900A
of SMUs greatly simplify the test Series of SMUs has a program The B2900A Series of SMUs also has
system configuration. As will be memory function that can be used to a data buffer on each SMU channel
discussed later, in most production improve production test throughput. that can hold up to 100,000 data
testing measurement results are Program memory allows you to store points. This enables you to transfer
compared with pre-defined limits and long strings of SCPI command lines all the data in the buffer at once after
pass/fail judgments are made. Output once into the volatile memory of the a series of measurements have com-
signals from the GPIO port of the B2900A Series of SMUs and then pleted instead of having to transfer
B2900A Series of SMUs can be used recall those strings multiple times data after every measurement. One
to communicate with the component while the program is executing using way to use this to improve throughput
handler to sort devices based on the a single SCPI command. By storing would be to have the B2900A Series
pass/fail criteria. the command strings in memory, the of SMUs send measurement data to a
time that would have been spent PC while a component handler places
sending those same commands over a new device on a DUT interface.
a communication bus is eliminated.

High force DUT interface

LAN Low force
USB GPIO Mechanical

Component handler

Figure 1. Example test system configuration using the B2900A Series of SMUs

Store Breakdown voltage test
Leakage current test
Forward voltage test

Program memory
SCPI command line strings

Figure 2. Program memory allows strings of SCPI commands to be stored for later

Multiple pass/fail
Characteristics of
judgment modes forward direction diodes
In production test, a limit test func- Characteristics of
tion is generally used to eliminate IF
reverse direction diodes
defective devices through a pass/fail
judgment based on pre-defined limits. SMU reaches compliance status
Recognizing that there are a variety of VF VComp
pass/fail limit scenarios, the B2900A PASS FAIL
Series of SMUs supports two modes:
Compliance mode and Limit mode Figure 3. Example showing how the Compliance mode's pass/fail test capability can be
(up to 12 binning limits possible). used to determine diode polarity

Compliance mode utilizes the intrinsic
compliance feature of the B2900A
Characteristics of the device
Series of SMUs that allows a limit
which passes in Limit Test
to be placed on voltage or current IF
output to prevent device damage. Characteristics of the device
When the SMU's output reaches the which fails in Limit Test
limit value during a measurement it is
in compliance status. If Compliance VLow VF VHigh VF FAIL
mode is enabled, then the test fails PASS
when the SMU reaches compliance
status. One possible use of this Figure 4. Example showing how the Limit mode's pass/fail test capability can be applied
feature is to determine the polarity to a diode forward voltage test
of diodes (please see Figure 3).

Limit mode is usually used to deter-
mine if a device parameter is within PASS
specified low and high limits. When FAIL Low1 Low2 High2 High1
Limit mode is enabled the B2900A A B C D E
Series of SMUs makes a Pass/Fail Limit 1 Measurement
judgment based on whether or not parameter
Limit 2
the measured value is within speci-
fied low and high limits (please see Bit pattern 100 010 000 001 011
Figure 4). A typical use of this mode If a device fails the Limit 1 tests, it will be sorted into bins A or E.
is to perform grading and sorting. For For devices that pass the Limit 1 tests, the Limit 2 tests will be performed.
example, using two binning limits If a device then fails the Limit 2 tests, it will be sorted into bins B or D.
in Limit mode it is possible to sort Devices that pass all of these tests will be sorted into bin C.
devices into five classes (please see
Figure 5. Example showing how to sort devices into five classes using two limit tests
Figure 5).

After performing pass/fail testing
with these modes, you can view
the results on the wide QVGA LCD
display of the B2900A Series of
SMUs. In addition, you can program
the B2900A Series of SMUs to output
specified Pass/Fail bit patterns
through the GPIO port to other equip-
ment such as handlers for component

Production diode test Start Summary
flow example The Agilent B2901/02/11/12A
Store SCPI command line strings Precision Source/Measure Unit is
Figure 6 shows a simplified flow to the program memory the best solution for the production
for production diode testing. Before
testing of diodes and other devices.
beginning the actual testing, it is Forward voltage test
The B2900A Series of SMUs pos-
good practice to store repeated
1. Force current IF sesses high throughput, which greatly
operations into the program memory IF
2. Measure voltage VF reduces test times. In addition, the
of the B2900A Series of SMUs (such
program memory function of the
as the forward voltage test in this VF
B2900A Series of SMUs allows the
example). After this test pre-loading
test throughput to be improved even
has been performed and the stored
RUN stored program more. The B2900A Series of SMUs
program has been run, the B2900A
also provides useful features for
Series of SMUs waits for a Start Wait for SOT production test such as pass/fail
of Test (SOT) trigger from the
decision-making, a digital I/O inter-
component handler. Once the diode Measurement face for handler control, and program
is in-place, the handler sends an SOT
Output pass/Fail pattern compatibility with standard single and
trigger signal to the B2900A Series
dual channel SMU products.
of SMUs to inform it that testing can
Output EOT
begin. The B2900A Series of SMUs
The B2900A Series of SMUs is
first makes a measurement using the Yes Another equipped with popular banana
program stored in program memory device? style terminals that make it easy to
and displays the Pass/Fail testing No connect to other instruments in a
result. Then, the B2900A Series sends
End production test system. Both SCPI
a specified Pass/Fail bit pattern and
commands and IVI-COM drivers are
an End of Test (EOT) signal to the
Figure 6. Diode production test flow available for the B2900A Series of
component handler and stores the
example using the B2900A Series of SMUs SMUs for remote control using the
test data to the PC. This procedure is
GPIB, USB or LAN communication
then repeated until all of the devices
have been tested.
Its wide current and voltage measure-
ment ranges (from 10 fA/100 nV
to 10.5 A/210 V) provide superior
measurement performance and allow
you to test devices more accurately
and easily than ever before.

For more detailed information on the
various models of the B2900A Series
of SMUs, please refer to the data
sheet of the B2900A Series of SMUs


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