Test system and methodology

Details Test system and methodology Test system and methodology

2002-07-16

2004-06-01

Zameke, David A. (Department: 2829)

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

C324S755090, C324S758010

Reexamination Certificate

active

06744267

ABSTRACT:

FIELD OF USE
This invention relates to test equipment and test techniques, especially equipment and techniques for testing electronic devices such as integrated circuits.
BACKGROUND ART
Integrated circuits (“ICs”) can be tested in various ways. One test technique is to electrically stimulate an IC and then monitor its electrical response, typically by comparing the actual response to a reference response. The stimulation/response-monitoring technique is commonly performed with automated test equipment connected to the external electrical leads, commonly referred to as pins, by which the IC interacts with the outside world. The test equipment stimulates the IC by providing electrical signals to the IC's pins and then monitoring the resultant electrical signals provided from the IC on its pins.
Another test technique involves probing an IC, especially when the IC has failed and it is desirable to determine the reason(s) for failure. The probing technique can be done by directing radiation, such as light or electrons, toward parts of the IC.
FIG. 1
illustrates a conventional test system that combines a stimulation/response-monitoring technique with an electron-beam probing capability for testing an integrated circuit
10
referred to generally as a device under test (“DUT”). The test system in
FIG. 1
consists of core automated test equipment
12
, manipulator
14
, test head
16
, tester load board
18
, interface module
20
, device-side load board (or card)
22
, and electron-beam probe system
24
which contains an electron-beam probe (not separately shown). DUT
10
is situated in probe system
24
and attached to device-side board
22
also situated in probe system
24
.
Interface module
20
interfaces between probe system
24
and test head
16
. Module
20
consists of tester-side body
26
, device-side body
28
, and flexible electrical cables
30
which pass through openings in bodies
26
and
28
to connect tester board
18
to device-side board
22
. Tester board
18
, which electrically connects head
16
to electrical cables
30
along tester-side body
26
, is customized to match head
16
. Different implementations of board
18
permit interface module
20
to be utilized with different versions of head
16
. Device-side board
22
, which connects cables
30
to the pins of DUT
10
, is similarly customized for testing DUT
10
. Different versions of board
22
enable module
20
to be employed with different types of DUT
10
.
During test operation, test equipment
12
generates electrical signals which are supplied through components
14
,
16
,
18
,
20
, and
22
to stimulate DUT
10
. The resulting electrical response from DUT
10
is then furnished in the other direction through components
22
,
20
,
18
,
16
, and
14
to test equipment
12
for evaluation. The electron-beam probe in probe system
24
probes DUT
10
to form an image of a portion of DUT
10
. The probing may be done as test signals generated by equipment
12
are used to stimulate DUT
10
. The flexible nature of cables
30
in interface module
20
substantially prevents vibrations in test head
16
from being transmitted through module
20
to probe system
24
.
Production units of an IC are commonly tested with automated test equipment in which a unit of the IC is attached to a production load board mounted directly on the test head of the automated test equipment. When the IC is also to undergo composite electrical testing/electron-beam probing using the test system of
FIG. 1
, device-side load board
22
is an additional load board that must be provided. That is, testing the IC entails designing two different types of custom load boards, device-side board
22
and the production load board mounted directly on the test head.
Rincon et al (“Rincon”), “A Custom Direct Dock High Speed Load Module and Lid for IDS Diagnostic Systems”, IDS User Conf. Advanced Training, Aug. 14, 1997, pages 1-5, describes how production testing of an IC and composite electrical testing/electron-beam probing of the IC can be done with only one custom load board.
FIG. 2
illustrates a somewhat simplified version of part of the test system employed by Rincon for performing composite electrical testing/electron-beam probing. Heat-exchange equipment, alignment features, and attachment hardware (bolts and screws) are not shown in
FIG. 2
to avoid illustration complexity.
For composite electrical testing/electron-beam probing, Rincon employs interface apparatus
32
for connecting electron-beam probe system
24
, a lid-modified variation of the Schlumberger IDS 10000® electron-beam probe system, to test head
16
of a Texas Instruments V-Series tester. The components of interface apparatus
32
include (a) main body
34
, (b) spring-loaded probes
36
that extend through openings in main body
34
, (c) vacuum seal board
38
that contacts test head
16
, and (d) vacuum seal ring
40
for hermetically sealing main body
34
to seal board
38
so as to maintain DUT
10
in a high vacuum provided by probe system
24
. Main body
34
is formed with three plates (not separately shown) bolted to each other. Spring-loaded probes
36
electrically connect seal board
38
to customized production load board
42
that receives DUT
10
along an opening in board
42
.
Lock ring
44
locks main body
34
of interface apparatus
32
to test head
16
. Another lock ring (not shown) locks load board
42
to main body
34
situated on lid
46
of probe system
24
. Item
48
in
FIG. 2
is a vacuum seal ring for hermetically sealing main body
34
to lid
46
. Item
50
is a column of the electron-beam probe. Opposite to what is illustrated in
FIG. 2
, DUT
10
can be mounted on the bottom side of load board
42
. In that case, spacers are placed between lid
46
and main body
34
to adjust the position of DUT
10
above probe column
50
.
By utilizing production load board
42
in the test system of
FIG. 2
, Rincon provides an economic advantage because only one type of custom load board needs to be designed to perform both production testing and composite electrical testing/electron-beam probing. However, vibrations can occur in test head
16
. These vibrations can be readily transmitted through lock ring
44
and main body
34
to probe system
24
. While the vibrations may not seriously impair the performance of the electron-beam probe, such vibrations can significantly impair the performance of certain other types of probes such as optical probes.
It is desirable to have a capability for performing electrical testing/probing with a composite test system in which the transmission of test-head vibrations to the probe is substantially avoided and in which units of the device under test are mounted on a load board that can be directly attached to the test head for additional, typically production, testing.
GENERAL DISCLOSURE OF THE INVENTION
The present invention provides such a test capability. In accordance with the invention, a system for testing an electronic device contains one or more test heads, one or more load boards for receiving units of the electronic device, a probe system having a probe, and an interface apparatus. When there are two or more load boards, the load boards have largely identical patterns of test-head signal transmission positions.
The test system is deployable in a direct configuration and in an interface configuration. In the direct configuration, one such load board is attached directly to one such test head for transmitting test signals through that board's signal transmission positions. One or more test operations are performed according to the invention as the load board receives a unit of the electronic device.
In the interface configuration, one such load board is coupled through the interface apparatus to one such test head for transmitting test signals through that board's signal transmission positions. The probe system contacts the interface apparatus or/and the load board. One or more test operations are performed according to the invention as the load board receiv

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