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SEMI M60-0305 © SEMI 2005 9 10.2.9 Check to see if there are any more MOS capacitors to be measured. If so, repeat from ¶10.2.4 until all MOS capacitors have been tested. A contact probe for all m easuring points elim in…

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SEMI M60-0305 © SEMI 2005 8
proper identification of the failure criteria. It is possible that rapid voltage changes at the dielectric breakdown of
the gate oxide cause electrical noise. There is a possibility that this noise leads to misjudgments of the oxide
breakdown. So it is desirable to confirm that oxide breakdown occurred. For example after the TDDB
measurement has been completed, the samples are measured to confirm their insulation. Mechanical stress due to
the exploring probe can influence the measurement results, because the exploring probe is in contact with the gate
electrode directly on the gate oxide. The actual results obtained depend somewhat on the sample fabrication
process. Care must be taken to ensure consistent processing. Wafer temperature during testing shall be clearly
defined. Large temperature variations might have an impact on results.
7.1.1 Precaution — Since the voltages and currents involved are potentially dangerous, appropriate means of
preventing the operator from coming into contact with the exploring probe or other charge surfaces shall be in place
before testing. This standard does not include any clauses relating to the safety and sanitation of the environment.
Those who intend to implement this standard shall consider appropriate means to prevent any accidents or disasters,
as well as taking responsibility for maintaining a state of safety, health and hygiene for users.
8 Sampling
8.1 Sampling is the responsibility of the user of this test method. However, if testing is carried out as part of a
comparison or a correlation, all participants shall agree upon sampling in advance.
NOTE 3: Refer to the appendix of JEDEC standard No.35 for good discussion of sampling plan statistics.
9 Apparatus
9.1 SEMI M51 and SEMI M1771 shall be applied for measurement equipment such as current/voltage source units
and manual probing machines
10 Procedure
10.1 Fabrication of MOS Capacitors
10.1.1 Refer to SEMI M51, introducing poly-silicon as an electrode material. Where another electrode material is
used, an appropriate method for each case and the correlation data between poly-silicon and the other material shall
be prepared.
10.2 Measurement
10.2.1 Before measurement, record the following information for each sample: date, time, operator, sample ID,
oxide thickness, gate area, gate material, oxidation condition, conductivity type (p or n), equipment ID, and
comments.
10.2.2 Decide on measurement parameters and record them. Constant current is applied in this test method. The
parameters include stress current density (J), measurement interval (T
int
), maximum stress time (T
max
), gate area (S),
judgment voltage of breakdown (V
bd
), measurement temperature, the number of capacitors to be measured and a
map of the capacitors.
10.2.3 Set a tungsten exploring probe at the starting position.
10.2.4 Set the exploring probe on a new MOS capacitor at the next position.
10.2.5 Set the accumulated time to zero (T (0) = 0). Record the oxide leakage current and the voltage.
10.2.6 Set the stress current to the designated point. Monitor the time (t) and the voltage (V
t
) from the start.
10.2.7 If the applied time is equal to or greater than the maximum stress time(t T
max
), record the maximum stress
time (T
max
) as the breakdown time (T
bd
) along with the MOS address, and proceed to ¶10.2.8. If t is less than T
max
,
proceed to the next step.
10.2.8 Check to see if the voltage Vt has reached the judgment voltage of breakdown (V
bd
). If so, record the time
(t), along with each MOS address, as the breakdown time (T
bd
), stop applying the stress current, and proceed to
¶10.2.9. If not, repeat from ¶10.2.6.
SEMI M60-0305 © SEMI 2005 9
10.2.9 Check to see if there are any more MOS capacitors to be measured. If so, repeat from ¶10.2.4 until all MOS
capacitors have been tested. A contact probe for all measuring points eliminates the need for repeat of the
measurement, and proceeds to the next wafer.
10.2.10 Report the results.
10.2.11 Figure 3 shows a flow diagram outlining the procedure for this test method.
10.2.12 For the judgment method of breakdown, not only fixed V
bd
but variation in voltage (V) monitored could
be used.
10.2.13 Figure 4 shows a flow diagram outlining the procedure for the test method when the judgment of
breakdown by drop in voltage (V) is adopted.
SEMI M60-0305 © SEMI 2005 10
Record Sample ID
Determine Test Parameter
J, T
int
., Tmax, Vbd
Probe New Cap.
Set
ｔ
= 0
Measure t, Vt
t > T
max
Vt > V
b
d
Record MOS ID &J
Stop & T
bd
= T
max
More Cap. on
Wafer?
Report Result
Yes
No
No
Yes
Yes
No
Record MOS ID &
J Stop & T
bd
= Vt
Force J ( I = J/Area)
Wait T
int
.
Figure 3
Flow Diagram Outline (1)