Chapter 8.05
Electroglas
Autoprobe in DCL
(autoprobe)
1.0
Title
Electroglas
Automatic Probe Station (autoprobe)
2.0
Purpose
This is a users' manual for the Electroglas autoprobe and the Metrics ICS program. The station can be used to test baseline chips and or other test structures. Large amounts of data can be collected to monitor the baseline process. This automated testing system was developed in conjunction with the BCAM test chip now used for baseline processing, and currently also by other members for their specific application.
3.0
Scope
Electroglas Autoprobe in DCL (Device
Characterization Laboratory, Room 407) is capable of electrical
testing 4" to 8” size wafers.
4.0
Applicable Documents
4.1
Hardware
This
document describes how to turn on the instrument, put in the probe card and
align the wafer. See Section 9.1.
4.2
Software
This section describes how to use Metrics ICS System Tools and Testing Tools to setup measurements for the test structure. See Section 9.3, the software setup and on line help files, documentation at: http://www.metricstech.com/icv/icv.shtml
5.0
Definitions, Process Terminology,
Equipment Configuration
5.1
Probe Card
A PC board
with specific conductive path and probe tips.
6.0
Safety
The surgical/poly gloves should be worn when handling the
probe card. Special care should be
taken when dealing with the probe tips as they are easily damaged.
7.0
Statistical/Process Data
Pertinent
information can be found on CMOS Baseline Information section of the Microlab’s
home page, http://microlab.berkeley.edu/baseline/index.html.
8.0
Available Processes, Process
Notes, and Hardware Modules
8.1
Machine
Components
The
probe station is comprised of different components.
8.1.1
Electronic
Rack: Tower is located to the left side of the probe station, 4084B switching matrix controller (SMC), and
the 4142B DC source/monitor, and 4280 1 MHZ Capacitance meter/C-V plotter.
8.1.2
Electroglas
2001 probe station: Microscope and 4085A switching Matrix module on top, joy stick box (key pads on it), control key
pad and monitor, in front of the station and camera lighting
electronic module/power supply units, just below the station.
8.1.3
PC and
Unix stations to invoke the test programs and their associated key pads located
to the right of the EG 2001 probe station.
9.0
Operation
The automatic probe station (autoprobe)
operation involves hardware and software set up to successfully perform
electrical parametric (I-V, C-V and resistance) measurement on device/IC under
test (4"-8" wafers). The
hardware part needs to be setup first, which includes probe card and wafer set
up. Once the wafer is ready (aligned and set on the chuck), the software
program can then be invoked to drive the stage, control metric switch, perform
the test routine/s and extract parametric data in a PC or a Unix based
workstation environment. The PC windows based program (recommended) called
Metrics I/CV by Metrics Technology is described in this section, as a primary
mode of operation. The second method Sunbase3 program (codes) is a Unix based
package(older software), also offers various measurement routines, but it is
somewhat more difficult to manipulate or add new test routines in it. For more
information on setup files, test routines and how to run the sunbase3 program,
refer to Appendix 2 and Appendix
3 (specific to baseline runs) at the end of this chapter. See Figure 13 for a picture of the entire system.
Probe
Card Set Up (Mounting/Replacing A Probe Card)
9.1.1
Swing
out the microscope assembly on the probe
station (the orange arm and the attached microscope) to the right and out of
the way. See Figure 14 in Section 10.
9.1.2
Unlock
the two metal locks, lift the buckle and slide down to free the locks at the
lower right side of the probe station. See Figure 15.
9.1.3
Slowly
lift the cover by the black handle. Be careful, it is very heavy.
9.1.4
Loosen
the three screws locking in the probe card plate, so that the pins held down by
the screws can rotate, Figure 16.
9.1.5
Rotate
the pins to free the plate.
9.1.6
Take
the plate out and put it back upside down, Figure 17.
9.1.7
If a
probe card is already in there, carefully take the probe card out. It might be
a little tight, but be careful not to break it.
9.1.8
Put
the probe card into an empty probe card container with the contact tips (not
the measuring pins) facing up. Close the lid of the container and put it away.
9.1.9
Take
the probe card that you want to use back in.
9.1.10
Line
up the two very small markers (two small dots) on the probe card with the red
arrows on the machine. Make sure the
probe card is securely put in.
9.1.11
Take
out the plate and put it back right side up. That is, flip the plate and put it
back the way you first saw it.
9.1.12
Line
up the plate as before and rotate the pins to lock the plate in place.
9.1.13
Tighten
the screws so that the pins can no longer move. Now the plate is securely
locked again.
9.1.14
Slowly
put the cover back down by the black handle. Again, be careful, because it is
very heavy.
9.1.15
Lock
the two metal locks on the right of the cover. If the locks are locked
correctly, you should see a red light go on directly to the left of the cover’s
black handle. The red light is labeled as OUTPUT ENABLED.
9.1.16
Put
the orange arm with the microscope attached back in.
Wafer Set Up
9.1.17
Use
different menus on the small monitor in front of the probe station to setup
your test parameters. The control key pad just to the front of this monitor (Figure 18), can be
used to enter parameters on various screens shown in Appendix 1. Normally the die size (x and y) and
wafer diameter are the only parameters that are needed to get changed, unless
someone else has changed other parameter for special application or mode of
operation.
Note: If the equipment is turned off, then turn
on the 4084B switching matrix controller (SMC), and the 4142B DC source/monitor
on the electronic rack. Turn on the probe station, next. There are two power
switches on the front panel of the station (camera lighting electronic module on top, and power
supply below it). Turn the top switch
first then the lower switch (do the reverse when powering down). The eglas
should power up with the message XY
motor blank on the monitor screen.
9.1.18
With
the main menu shown on the screen, press SET PRMTR (set parameter) key
on the control pad to go to the parameter screen. Set the die size and the diameter
of the wafer with option 1 and 4 (type 01 and 04 followed by enter key). Input
the new value/s followed by return key (Enter key is black button on the bottom
where the broken white key should have been). Press the enter key again
to go back to the initial screen, shown in Appendix 1.
9.1.19
Press SET
OPTION and make sure that option 02 (Auto Align), option 03 (Auto Profile)
and option 08 (Auto Temperature) are all enabled.
9.1.20
Press SET
MODE key on the control panel to check the status of theta compensation
on the screen. For automatic mode of operation, testing many dies
automatically, you will need to have theta compensation disabled. You can enable theta compensation (option
11) in the SET MODE menu, if you need to perform manual wafer
alignment/testing.
Note: when inside a menu you can type in the option number
followed by the enter key to select, and then change the value of that
particular option. Otherwise you can
get out of the menu by pressing the designated key on the control pad. Check Appendix 1 for more detail on the content of different
menus and submenus.
9.1.21
Press
the force release button, which is a small button inside the circular
hole on the left side of the joystick box to release the vacuum on the wafer
chuck assembly. See Figure
19.
9.1.22
Now
with the vacuum released, the chuck assembly should be free to slide around on
the platform. Slide the chuck assembly to the front-right corner of the work
surface (probe station platform) closest to you, so that you can load your
wafer. Check that the orientation of the dice is roughly parallel to the axes
of the probe workspace. The wafer can only be rotated by ~15 degrees after it
is loaded, and it's much easier to do it right from the start.
9.1.23
Press
the small button (force release button) on the left side of the joystick box
again to enable the vacuum on the chuck assembly.
9.1.24
Setting
a reference point - press [FIND TARGET] the wafer should move under the camera
resulting in an image appearing on the monitor. Looking at the monitor and
image of the die, use the joystick to find a reference. This will be a unique
non-repeating pattern on your die that can be moved into the white square box
on the screen. Once set, go to the next step.
Note 1: Press
CAMR the camera button on the joystick, If no image is shown on the
screen post FIND TARGET step. If still a problem, proceed to instruction
given in the Troubleshooting Guidelines, Section 9.2.
Note 2: The
joystick has three modes of speed, which can be selected by turning it
clockwise or counter clockwise. These
speed settings can give you the fine movement, die size stepping and continuous
motion, depending on what mode you choose (jog/index/scan)
9.1.25
Press
[PAUSE/CONT] on the joystick box to start scan. A number should show up on the
screen, while the wafer gets mapped (scanned). The bigger this number the
better the fit and referencing process. Refer to Section 9.2,
If any error or warning comes up, i.e. Ref
Not Stored. If all goes
well, then you should end up in the initial screen with a message asking you
for a second reference (2nd REF). You do not need to scan the second
target, just press [ENTER] twice on the next two messages (second ref
and find edge questions). This will take you back to the initial screen.
Note: If
you only have a few dies on your wafer and do not need to perform automatic
probing, you will still need to perform the find target procedure. This
time however, you will end up with Ref Not Stored warning, which can be
bypassed (Do not trouble shoot it, proceed to the next step, 9.1.26). Please
also note, in that situation you would have enabled the theta compensation
option, earlier (SET MODE screen and line 11, enabled). which means the auto
align operation are to be skipped, while testing the die at the later steps.
9.1.26
Press PROG
(program) on the monitor panel.
9.1.27
Select
option 04, to profile. This will adjust the tilt of the wafer automatically.
The chuck will go to a pre-specified location, and then will move around a bit
as the wafer is profiled. After the profiling is done, the chuck should end up
under the microscope.
9.1.27.1 Occasionally,
the chuck will not initiate from a correct position on the platform. If this
happens, press load to move the chuck back home, and then press force
release button on the same joystick box, and move the chuck to front right
corner of the platform, essentially need to start over at step 9.1.21.
9.1.28
Press
3 in the G-PROFILER menu (same menu) to set the Z - height, which is the
vertical height of the wafer.
9.1.29
Press Z
on the joystick box; adjust the height with respect to the probe tips as per
next step.
Note: You
may need to move your wafer into a proper position for the Z-height adjustment
procedure. You can do this by pressing the X and/or Y keys on the
control panel (Figure 18).
9.1.30
While
looking into the microscope, use the joystick to move the wafer up and down to
adjust the z height. The probe tips should come in focus under the microscope,
but you need to move the wafer into focus manually. This means moving the stage
up, while looking into the microscope (always). You can press and hold the red
button on the joystick to speed up the z-movement, but be careful not to crash
the tips into your wafer (avoid tip damage/deformation). Release this button
when tips get close to surface of your wafer, and watch carefully for any sign
of tips getting deflected (bend outward). Probe tips’ shape change is an
indication of wafer pressing against the probe tips, therefore you should not
move the wafer up any further. Adjust the z height, so that the probes just
touch the wafer, but not pressed against it too much. The z height is
numerically displayed on the display monitor, during the Z-height adjustment.
The correct value (height) should be somewhere around 310 mils for a typical
6-inch wafer.
Important note! Always look into the microscope
instead of the monitor, while adjusting the z height. This will prevent you
from overdriving the tips into the substrate, hence damaging the probe card.
9.1.31
Look
at the final z height on the monitor after you are done adjusting the height;
make a mental note of the value.
9.1.32
Press ENTER
to go back to the original menu and follow with the next step. This is an
additional step required to store the z-height value by essentially repeating
the z- height set up twice, as per follows.
9.1.33
You
need to check to make sure that the z height is now set at the same value as in
the previous step. This can be done by pressing PROG key, and selecting
option 3 in the next menu, G-PROFILER menu for the Z-height set- up. Once you
confirmed that the Z- height has a correct value, press ENTER to get
back to the original menu. This second round is always needed, as it will store
your previously set Z- height value.
9.1.34
The
wafer setup is now complete, however, if you need to make any final X& Y
adjustment, then press the Z button on joystick box to lift the probe
tips off the wafer, before stepping the wafer in such direction/s. Press Z
again to put the probe tips back on the wafer, after your X and/or Y movement
has placed the probe tips exactly where you want them to land (device pad, so
on).
9.1.35
Press LAMP
button on joystick box to turn off the lamp.
9.1.36
You
can start your measurements as per instructions defined in Section
9.3 for a PC based program or in a UNIX environment (sunbase3 program), as
per described in Appendix 2.
Note: Baseline
runs (test chips), which are regularly processed by staff can also be tested
through sunbase3 program, as described in Appendix 3.
Optional Stage / Wafer Rotation
Adjustment
Please note, the Theta
compensation should be enabled for this section. This can be done by changing
its status in the SET
MODE sub- menu
(press SET MODE key on the control panel to get to this sub-menu).
9.1.37
The rotation
is automatically adjusted, but if more accurate theta setting is required
(probe tips are not stepping in the exact position on all dies, across your
wafer), then follow the next step.
9.1.38
Press ALIGN
SCAN on the joystick box, see Figure 19.
9.1.39
Pressing
PAUSE/CONT on the joystick box once, will scan the probe over the wafer
once. Correct the theta rotation as per follows.
9.1.40
While
the wafer is getting scanned (moving back and forth horizontally follow the
scribe lanes or an edge of a unique feature under microscope. You need to have
no movement along the Y-axis looking at these features. You can correct for any
misalignment observed by rotating/holding the joystick in a proper direction to
correct for rotational error. You can also hold the red button on top of the
joystick to speed up the process. (9.1.37 and 9.1.38).
Note: Holding
the joystick button for a second or two will activate a buzzing sound.
9.1.41
Once
there is no movement in the Y direction and pattern cruise by nicely aligned
with the probe tips, then your Theta is perfectly aligned. You can stop the
scan, go to next step.
Press PAUSE/CONT to stop the scan.
You should be ready
to start your measurement as per Section 9.3 or Appendices 2 and 3, as was
described earlier.
Changing or Unload A Wafer
9.1.43
One
can change or unload the wafer at anytime by the following steps.
9.1.44
Pressing
[LOAD] button on the joystick box (Figure 19) will bring
the chuck back to the lower right corner of the platform. You can push the
force release button on the left side of the joystick box to lift up/release
the wafer. Now you can remove or exchange wafer at this point.
HELPFUL
KEYSFP
[x] enables
the joystick to move in the x and y direction
[z] enables
the joystick to move in the z direction
[lamp] turns on the lamp for the
microscope
[e+nter] exits out of current menu
if an exit option is not given.
Note:
See Figures
18 and 19.
9.2
Troubleshooting Guidelines (Hardware
Set Up Part)
No Image After Find Target Step (9.1.24)
9.2.1
If
after pressing FIND TARGET button, no image shows up on the
screen, follow the next steps to resolve this issue.
9.2.2
Press CAMR
button on the joystick box, and if there is still no image on the screen, then
go to next step.
9.2.3
Press
load on the joystick pad, stage comes back to the right corner of the station
platform.
9.2.3.1
Press
the force release button on side of the joystick box to release the
wafer.
9.2.3.2
Remove the wafer [just like in step 9.1.22,
above].
9.2.4
Reboot
the upper electronic rack just below the probe station called camera
lighting by pressing the ON/OFF switch and wait for 20 seconds before
turning it back on again.
9.2.5
Follow
steps 9.1.22 through 9.1.24 to
load the wafer back on stage and go through FIND Target step again.
XY Motor Blank Warning
9.2.6
You
may get the XY motor blank warning/error, on the monitor, which will
stop you from getting into the menu and various sub-menus.
9.2.7
Press force
release button on left side of the joystick box, see Figure
19.
9.2.8
Once
the stage is vacuumed down the warning should clear.
Ref Not Stored Warning
9.2.9
Try a
new non-repeating target to try.
9.2.10
Press FIND
TARGET on the control panel, Figure 18. this time find
a more recognizable non-repeating target, then press PAUSE/CONT key on
the joystick box to resolve the issue.
9.2.11
If
still a problem, check your die size and remember you need to account for the
scribe lane when calculating for this. Check/verify correct dies size on the
setup menu to remedy the problem.
Error "Clean position Z
(Z-height) not adjusted"
9.2.12
[step 9.1.33] if the
messages clean position
z not adjusted or/and
continuity test z not
adjusted error/warning comes up, z
height can still be set with these messages, however, it is better to perform
the set ups again, as a precautionary
measure to keep the probe card from getting damaged.
Using
the Metrics I/CV Tools
We will be
using the Metrics I/CV system tools and testing tools. Shortcuts to these two programs can be found
on the desktop of the computer by the probe station. Figure 1 shows the icon for these two shortcuts. I-CV System Tools is a package that
allows you to setup the tests that you want to run. I-CV Testing Tools is a package you can use to run the
test/s. We will not need many of the
features in these two packages for simple tests. If more advanced features are needed, please refer to the help
files or the online documentation: http://www.metricstech.com/icv/icv.shtml.
Figure 1 - Metrics
I/CV Software Shortcuts
The metrics
software is a modular package that is configurable from the device to wafer
levels.
Figure 2 - Metrics I/CV System Tools Menu
How To Built Up A Test Using Metrics I/CV Tools
The following steps are necessary to build up a test plan for a
particular test (Figure 3).
i.
Pin
assignment: connection between the pins on the probe card and measurement
instruments (Metrics Switch)
ii.
Measurement
definition for a single device (Metrics ICS)
iii.
Module
definition: measurements at a single placement of the pins (Module Editor)
iv.
Die
module: multiple measurements within a single die (Die Editor)
v.
Wafer
Plan: which dice on the wafer are to be evaluated (Wafer Map Editor)
Figure 3
9.3.1 Pin Assignment
Connections between the
pins on the probe card and measurement instruments are defined in the Metrics
Switch software. This is where the physical
connections between the device under test (DUT) and measurement channels are
defined. A subset of the probe card
pins is associated with the inputs and outputs of the HP-4142B.
9.3.1.1
Open
the Metrics Switch program from the Metrics I/CV System Tools program bar
(Figure 2).
9.3.1.2
Select
New from the menu to configure a new switch setting or open an existing
template to modify. If opening a
template, use the Save As… command to save the new switch setting before
modifying the file.
9.3.1.3
Verify
that the file name is correct in the upper portion of the window.
9.3.1.4
Set
the Autoprobe switch as active (Figure 4).
Figure 4
9.3.1.5
Double
click on the active switch to configure the switch settings.
9.3.1.6
Select
the check boxes that correspond to the pin to connect to the desired source/measurement
channel. The upper labels on the
columns correspond to the connections to the pin board that interfaces with the
switching matrix. The lower column
label shows the pin number on the probe card.
The correspondence between the switching matrix channels and the probe
card pins is determined by how the probe card is installed in the mount. The labels serve as a reference only and
maybe edited for measurement clarity (Figure 5).
Figure 5
9.3.1.7
Press
the Exit button to close the active switch dialogue.
9.3.1.8
Save
the new switch configuration.
9.3.2 Measurement
Definition
Measurements
for a single device are configured in the Metrics ICS software. Measurement parameters are defined and
associated with a switch setting for a single pin placement.
9.3.2.1
Open the
Metrics Switch program from the Metrics I/CV System
9.3.2.2
Select
New from the from the file menu to create a new measurement.
9.3.2.3
Measurements
are saved in project files with other measurements. From the File menu select Set project to define a new project or
open an existing project. When the
measurement is saved, it will be a unique measurement in the project file.
9.3.2.4
Select
the instruments icon to select the measurement instruments. The available instruments are the HP4142B
and HP4280.
Figure 6
9.3.2.5
The Metrics
Switch interface maybe controlled through the ICS software. Be sure that Enable Switch Control is
selected so switch settings maybe defined in the measurement definition.
9.3.2.6
Select
the Edit Test Setup command to configure a new measurement.
Figure 7
i.
Select
the New button to configure a new measurement.
ii.
Select
the Device button to define a new measurement with the proper polarity (Figure
6).
iii.
Select
Source Units (Figure 7)
1.
Use
the Instruments button to choose the desired source/measurement instrument.
a.
You
cannot use source units from more than one instrument.
2.
Use
the Source Units button to pick the desired measurement channel.
a.
Highlight
the desired channel in the Source units window and select the appropriate
terminal on the device. Repeat for each
terminal on the device.
b.
Parameters
for the source units can be configured by clicking on the source unit icon at
the device terminal.
iv.
Select
the Switch button to choose the switch configuration to use with the
measurement.
v.
The
Time button will open the time based measurement configuration dialogue.
9.3.2.7
To
test a measurement or make a spot measurement, position the probe card at the
appropriate device and open the Measurement Remote Control (Figure 8).
Figure 8
9.3.2.8
The data
plotter is used to display data taken by the current measurement (Figure 9).
Figure 9
9.3.2.9
The
transform editor is used to automatically extract parameters from the current
measurement. The extracted parameter
will be saved in the raw data file (Figure 10).
Figure 10
9.3.2.10
Save
the measurement to the appropriate project file.
9.3.3
Test
Module
Defines
the switch settings and measurements to be executed at a single placement of
the pins. Test modules are defined in
the Module Editor. Parameters and
variables may be passed to the measurement in the module script.
9.3.3.1
0pen
the Module Editor from the Metrics I/CV System Tools program bar.
9.3.3.2
Select
a new or existing script file (*.scr) from your directory.
9.3.3.3
Use
the Add Line and Insert Line commands to add new
measurements.
9.3.3.4
A
basic script file will consist of connecting a switch setting and running an
ICS Test.
9.3.3.5
More
advanced scripting can be executed through the module editor. Refer to the help file for definitions and
examples of the available commands.
9.3.4
Die
Module
Multiple measurements within a single die are defined in the Die Editor. The die script defines the movements of the pins within a single die and which module scr