United States District Court, N.D. California
AMENDED ORDER DENYING DEFENDANT'S MOTION TO
DISMISS RE: DKT. NO. 49
M. Ryu, United States Magistrate Judge
SEMICAPS Pte Ltd. (“SEMICAPS”) filed this patent
case against Defendants Hamamatsu Corporation, Hamamatsu
Photonics K.K., and Photonics Management Corp. (collectively,
Defendants or “Hamamatsu”), alleging that
Hamamatsu infringes the claims of U.S. Patent No. 7, 623, 982
(the “‘982 patent”), which relates to
testing of electronic circuits using a laser. Hamamatsu moves
to dismiss the complaint, arguing that the asserted claims
are invalid because they claim patent-ineligible subject
matter. [Docket No. 49.] The court held a hearing on July 11,
2019. For the following reasons, the motion is
The ‘982 Patent
is the owner by assignment of the ‘982 patent titled,
“Method of Testing an Electronic Circuit and Apparatus
Thereof.” Compl. ¶ 11, Ex. A (‘982 Patent).
The ‘982 patent was issued by the United States Patent
and Trademark Office (“USPTO”) on November 24,
2009, and “relates generally to semiconductor
processing, and more particularly to a method of testing an
electronic circuit, as well as to a respective apparatus,
” ‘982 Patent 1:6-8, in order to “determine
the location of defects on the semiconductor circuit.”
describes the relevant technology as follows:
newly-fabricated integrated semiconductor circuits are
“typically tested by connecting them to electronic test
equipment that applies test signals to each integrated
circuit and receives output signals from the circuit as a
result.” Id. While this method of testing can
reveal defects, it does not identify the location of the
defect in the integrated circuit. In order to determine the
location of the defect, fabricators use “failure
analysis systems . . . to perform fault localization testing,
” which can be done using lasers in scanning
microscopes. Id. at 3-4.
‘982 patent's background information describes the
problem the patent seeks to solve. It explains that
“conventional laser induced techniques generally
involve using a scanned laser beam, typically in the infrared
frequency range, to stimulate integrated circuit failures
which are sensitive to thermal or carrier
stimulations.” ‘982 Patent at 1:16-19. These
techniques include Optical Beam Induced Resistance Change
(“OBIRCH”), Thermal Induced Voltage Alteration
(“TIVA”), and Differential Resistance Measurement
(“DReM”). Id. at 1:22-27. However,
advances in integrated circuit technology, including
“the use of more metallization layers and new low k
inter-layer dielectric materials with lower thermal
conductivity, ” have reduced the laser coupling
efficiency, which in turn reduces the detection sensitivity.
Id. at 1:28-33. The inventors explain that
“conventional approaches” to improve the
detection sensitivity of laser induced techniques have not
been entirely successful. For example, increasing the power
of the laser beam used “in order to compensate for the
reduced laser coupling efficiency . . . may not be desirable,
” because “there may be potential laser induced
damage on the integrated circuit under test when the power of
the laser beam used is too high.” Id. at
1:38-49. Another approach is to use “a pulsed laser in
conjunction with a lock-in amplifier, ” which increases
detection sensitivity. Id. at 1:50-52. However,
lock-in amplifiers are “not used in a real-time
integrated circuit testing environment” because
“accurate calibration and fine control of the lock-in
amplifier parameters is typically difficult to achieve in
practice.” Id. at 1:62-67.
‘982 patent attempts to increase detection sensitivity
in a laser-based fault detection system without increasing
the power of the laser beam or using lock-in amplifiers.
‘982 Patent at 10:19-46. According to the patent,
“[t]he method comprises radiating a laser beam onto the
electronic circuit, and determining a plurality of samples of
a response signal output by the electronic circuit during the
period when the laser beam is radiated.” ‘982
Patent, Abstract. A signal processor “process[es] the
sample measurements of the response signal of the electronic
circuit under test” by “accumulat[ing] the
plurality of samples to generate a value, and then
generat[ing] a test result based on the value
generated.” ‘982 Patent at 3:65-4:2. Based on the
generated value, a fault on the electronic circuit may appear
as a bright spot, bright line, or bright area at a pixel
location corresponding to the location of the fault on the
electronic circuit. Id. at 4:16-24, 4:34-38,
‘982 patent includes 25 claims. SEMICAPS alleges that
Hamamatsu infringes at least claims 4-7 and 21-25. Compl.
¶ 13. At the hearing SEMICAPS represented that it also
asserts claims 8 and 17. See Mot. 12 n.3; Opp'n
1. Claims 4-8 and claim 17 pertain to a method of testing an
electronic circuit, while claims 21-25 describe a related
Claims 4-8 and Claim 17
4-8 depend from independent Claim 1, which states:
1. A method of testing an electronic circuit, comprising:
radiating a laser beam onto the electronic circuit,
determining a plurality of samples of a response signal
output by the electronic circuit during the period when the
laser beam is radiated,
accumulating the plurality of samples to generate a value,
generating a test result based on the value.
‘982 Patent at 10:59-67.
Claims 4-8 and claim 17 add the following limitations to
4. The method of claim 1, wherein the laser beam is a pulsed
5. The method of claim 4, wherein the frequency of sampling
of the response signal is higher than the frequency of the
pulsed laser beam.
6. The method of claim 4, wherein the frequency of the pulsed
laser beam is in the range from about 50 Hz to about 50 kHz.
7. The method of claim 4, wherein the frequency of sampling
of the response signal is in the range from about 100 kHz to
about 80 MHz.
8. The method of claim 1, wherein accumulating the plurality
of samples is performed after a predetermined time delay from
the start of the period when the laser beam is radiated.
17. The method of claim 1, wherein another plurality of
samples of another response signal output by the electronic
circuit during a period when the laser beam is not radiated
is determined, the other plurality of samples is accumulated
to generate another value and the test result is generated
based on the value and the other value.
‘982 Patent at 11:8-22, 12:4-9.
21 is an independent claim and describes an apparatus:
21. An apparatus, comprising:
a laser beam source, wherein the laser beam source radiates a
laser beam onto the electronic circuit,
a control system operable to direct the laser beam source to
dwell on a location on the electronic circuit,
a measuring circuit, wherein the measuring circuit determines
a plurality of samples of a response signal output by the
electronic circuit during the period when the laser beam is
a signal processor, wherein the signal processor accumulates
the plurality of samples to generate a value, and generates a
test result based on the value.
‘982 Patent at 12:19-31. Claims 22-25 depend from claim
21. They recite:
22. The apparatus of claim 21, wherein the control system is
operable to move the laser beam source according to a pattern
over a plurality of locations on the electronic circuit.
23. The apparatus of claim 21, wherein the laser beam is a
pulsed laser beam.
24. The apparatus of claim 23, wherein the frequency of
sampling is higher than the frequency of the ...