Appeal 2006-3235
Reexamination Control No. 90/006,696
1 25. Under the heading “Conclusion,” Fleuren states that the disclosed
2 thermotropic use of nematic liquid crystals “is nondestructive, fast, cheap,
3 simple and very sensitive (.1 ºC and 1 µm2) technique. It is applicable to all
4 kind of semiconductor processes and has proven itself over the years as
5 ideally suited for (failure) analysis purposes.” Id. at 149.
6 Stephens (Br. Ex. J; Reexam. Ex. 6)
7 26. As rebuttal to Appellant’s argument that “hot spot” detection is
8 limited to failed or defective devices, the examiner relies on C.E. Stephens
9 and F.N. Sinnadurai, A Surface Temperature Limit Detector Using Nematic
10 Liquid Crystals with an Application to Microcircuits, 7 Journal of Physics E:
11 Scientific Instruments 641-43 (1974) (“Stephens”). Answer 11.
12 27. Stephens discloses using any of various nematic liquid crystal
13 materials for “hot spot detection” in microcircuitry that is not characterized
14 as including a failed device:
15 3.3 Microcircuit hot spot detection
16 To illustrate the use of the technique in locating hot spots
17 in microcircuits, an operational amplifier was coated with
18 a nematogen film. Bias was applied to the circuit and the
19 power dissipation increased until a dark area appeared in
20 the film[,] which happened at the contact between a
21 metal track and a diffused resistor (figure 4). The
22 nematogen was then removed from the microcircuit
23 surface, and the area around the hot spot was investigated
24 with the infrared microradiometer, figure 5 indicating
25 surface temperatures at various points in the vicinity of
26 the hot spot. The isotropic transition of the nematogen
27 gives a clearly visible profile confirming the infrared
28 microradiometer measurements, but without the need for
29 reference to calibrations.
19
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