Delta V Instruments is a worldwide
manufacturer of Package Level
Burn-in Systems, Wafer Level Burn-in
Systems, Custom Systems, Test
Fixtures and Burn-in Test Services.
Copyright 2011 RJI Management, LLC      All rights reserved.

As the industry moves towards KGD and multi-chip
modules there is an increasing need for burn-in
systems capable of performing the burn-in test
function at the wafer level. These wafer level burn-
in systems are being designed around several
driving factors:

Process Control Feedback to the FAB
The WLBT system can be used to perform process
control feedback by running 'test wafers' along with
the production run. These 'test wafers' can be
designed to include several hundred product die
along with test sets designed specifically to qualify
the manufacturing process.

Early Life Failure (ELF) Data
The 'test wafers' would allow ELF data feedback
within hours of manufacture rather than weeks if
packaged burn-in is used. Since the 'test wafers'
are discarded after use, the process step for
removing the sacrificial metal layer is not required.

Need for Known Good Die (KGD)
KGD required for multi-chip modules and system-on-
chip (SOC) packages. WLBT eliminates the need
for special chip carriers to heat and test bare die so
providing a cost effective solution.

Reliability Test Screening
For ≤0.18 micron process, Iddq measurements are
problematic and unsuitable for KGD reliability test
screening. WLBT eliminates the need to perform
this type of testing.

Cost savings
WLBT catches early life failures (ELF) in marginal
and defective devices before wafers reach final
packaging and test. WLBT performed using DFT
structures can dramatically reduce the need for
automated test equipment (ATE). Reducing the use
of expensive ATE and catching ELF’s prior to
packaging can result in cost savings of more than
50% when volumes exceed one million units per
year ¹. WLBT can decrease or eliminate costs
associated with package level burn-in.

Test During Burn-In (TDBI) technology
An increasing proportion of bare die have higher
complexity and speed. Many devices are now
having DFT features built in.

A cost-effective interface between wafer and
test hardware
Alignment between wafer and contactor is critical to
the test process. I/O fan out, small die pitch,
circuitry routing all need to be considered when
developing test circuitry.

Electrical requirements
Die isolation is essential to perform effective testing.
Power dissipation per wafer can be in the 1-2kW
range. BIST allows the die to operate at speeds
beyond package level burn-in, so increasing the
need for efficient current management.

Thermal management
Hot/Cold testing (-55ºC to +180ºC).

¹ Study conducted by Austin-based Microelectronics and Computer
Technology Corp.
Delta-V's WLBI System

While there are several other potential
solutions in development at other
vendors, Delta V Instruments has a
proven platform, currently being used
in a production environment by a
leading microprocessor manufacturer.
This platform makes use of a
‘sacrificial metal’ technique for
interconnection and a ‘clustering’
scheme to limit the number of I/O lines
required for test. This minimizes the
need for full point to point contact
directly onto the wafer. By taking this
approach the customer greatly
reduces the costs associated with
custom test fixtures and eliminates
potential wafer damage or false failure
reporting due to misalignment of a full
contact solution.

Delta's stimulus hardware makes full
use of all DFT features built into the
device under test. When used in
conjunction with wafer level integrated
test chip technology our solution to
WLBT ensures a high volume
throughput with high visibility testing
and feedback monitoring for both
qualification and production
Contact RJI Technical Sales with any
questions you may have related to
this exciting technology.  Thanks.