Atty. Docket No. MIT-7581L-RX1
`
`IN THE UNITED STATES PATENT & TRADEMARK OFFICE
`
`IN RE PATENT OF:
`
`Joseph BERNSTEIN et al.
`
`PATENT NO.: 6,057,221
`
`SERIAL NO.: 08/825,808
`
`ISSUE DATE: May 2, 2000
`
`FILING DATE: April3, 1997
`
`CONTROL NO.: 90/011,607
`
`ASSIGNEES:
`
`MASSACHUSETTS INSTITUTE OF TECHNOLOGY;
`THE UNIVERSITY OF MARYLAND
`
`FOR: LASER-INDUCED CUTTING OF METAL INTERCONNECT
`
`I hereby certify that this document is being transmitted to the USPTO or deposited with the United States Postal
`Service as first class mail in an envelope addressed to Commissioner for Patents, P.O. Box 1450, Alexandria, VA
`22313-1450, on March 26,2012.
`
`/Jennie Heaton/
`By: ________________________________ __
`Jennie Heaton
`
`REQUEST FOR RECONSIDERATION IN EX PARTE REEXAMINATION
`PURSUANT TO 37 C.P.R. 1.530 and 1.550
`
`Mail Stop EX PARTE REEXAM
`COMMISSIONER FOR PATENTS
`P.O. BOX 1450
`ALEXANDRIA, VA 22313-1450
`
`SIR:
`
`Responsive to the Office Action dated January 26, 2012, Patentees respectfully request
`
`reconsideration of the above-identified reexamination application in view of the accompanying
`
`amendments and the following remarks.
`
`IPR2015-01087 - Ex. 1015
`Micron Technology, Inc., et al., Petitioners
`1
`
`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`Remarks
`
`Patentees and their representatives wish to thank Examiner Heyman for the thorough
`
`reexamination of U.S. Pat. No. 6,057,221 (hereinafter, the "'221 Patent") and the detailed
`
`explanations in the Office Action dated January 26, 2012. The Examiner's concerns have been
`
`given serious consideration. However, in view of the accompanying amendments and the
`
`following remarks, the present claims are allowable over the cited references.
`
`Claim 3 is directed to a method for cutting a link between interconnected circuits,
`
`comprising the steps of (i) directing a laser upon an electrically-conductive cut-link pad
`
`conductively bonded between a first electrically-conductive line and a second electrically(cid:173)
`
`conductive line on a substrate, the cut-link pad having substantially less thermal resistance per
`
`unit length than each o(the first and second lines, wherein the width ofthe cut-link pad is at
`
`least ten percent greater than the width o(each o(the first and second electrically-conductive
`
`lines, and (ii) maintaining the laser upon the cut-link pad until the laser infuses sufficient energy
`
`into the cut-link pad to break the conductive link across the cut-link pad between the pair of
`
`electrically-conductive lines, wherein the electrically-conductive cut-link pad has an inner
`
`surface facing the substrate and an opposing outer surface facing away from the substrate, the
`
`first and second electrically-conductive lines extending from the inner surface into the substrate.
`
`Claim 14 is directed to a method for cutting a link between interconnected circuits,
`
`comprising the steps of (i) directing a laser upon an electrically-conductive cut-link pad
`
`conductively bonded between a first electrically-conductive line and a second electrically(cid:173)
`
`conductive line on a substrate, the cut-link pad having substantially less thermal resistance per
`
`unit length than each of the first and second lines, wherein the cut-link pad is covered with!!:.
`
`passivative layer that is harder than the substrate; and (ii) maintaining the laser upon the cut(cid:173)
`
`link pad until the laser infuses sufficient energy into the cut-link pad to break the conductive link
`
`across the cut-link pad between the pair of electrically-conductive lines.
`
`The references cited in the Office Action dated January 26, 2012 (i.e., Koyou, Japan Pat.
`
`Appl. Pub. No. 8-213465, published Aug. 20, 1996 [hereinafter "Koyou"], Wada, et al., Japan
`
`Page 2 of33
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`2
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`Pat. Appl. Pub. No. 6-244285, published Sep. 2, 1994 [hereinafter "Wada"] and Lou et al., U.S.
`
`Patent No. 5,729,042 [hereinafter "Lou"]) neither disclose nor suggest a method for cutting a
`
`link between interconnected circuits, comprising directing a laser upon an electrically-conductive
`
`cut-link pad having substantially less thermal resistance per unit length than each of the first and
`
`second electrically-conductive lines conductively bonded thereto, and:
`
`•
`
`the cut-link pad has (i) an inner surface facing the substrate and an opposing outer
`
`surface facing away from the substrate, and the first and second electrically(cid:173)
`
`conductive lines extend from the inner surface into the substrate (see, e.g., Claims
`
`3, 17 and 26) and (ii) a width that is at least ten percent greater than the width of
`
`each of first and second electrically-conductive lines (see, e.g., Claims 3 and 17);
`
`or
`
`•
`
`the cut-link pad is covered with a passivative layer that is harder than the substrate
`
`(see, e.g., Claim 14).
`
`Consequently, the present claims are patentable over the cited references.
`
`The Rejection of Claim 23 under 35 U.S.C. § 112, Second Paragraph
`
`The rejection of Claim 23 under 35 U.S.C. § 112, second paragraph, is respectfully
`
`traversed.
`
`A via is a common structure in semiconductor devices, and the term has a clear meaning
`
`to those skilled in the art. It is also understood in the art that a via can have a cross-sectional
`
`area. The cross-sectional area of the via has two dimensions, and is thus definable by one or two
`
`dimensional components, depending on the cross-section and the shape of the via. For example,
`
`in a side view, the cross-sectional area of the via may be defined by the width of the via and the
`
`height or depth of the via.
`
`In a top-down view, when the via is substantially square or
`
`substantially circular, the cross-sectional area of the via may be defined by the width of the via
`
`alone (a square having an area that is the square of the width, and a circle having an area that is
`
`Page 3 of33
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`3
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`proportional to the square of the radius, a dimension that is equal to half of the diameter or
`
`width). Thus, the cross-sectional area of a via can be defined at least in part by the width of the
`
`VIa.
`
`Although Claim 23 does not require that the cross-sectional area of the via be defined by
`
`two specific dimensional components (which is not necessary in at least two possible
`
`embodiments of the invention), Claim 23 also does not exclude the possibility of a second
`
`dimensional component contributing to the definition of the cross-section of the via. As a result,
`
`the rejection of Claim 23 under 35 U.S.C. § 112, second paragraph, is improper and should be
`
`withdrawn.
`
`The Rejection of Claim 11 under 35 U.S.C. § 102(b)
`
`The rejection of Claim 11 under 35 U.S.C. § 102(b) as being anticipated by Nishimura
`
`has been obviated by appropriate amendment.
`
`The Rejection of Claims 3, 4, 6-8,23, 25,26 and 28 under 35 U.S.C. § 103(a)
`
`The rejection of Claims 3, 4, 6-8, 23, 25, 26 and 28 under 35 U.S.C. § 103(a) as being
`
`unpatentable over Koyou in view of Wada is respectfully traversed.
`
`As explained below, Claim 3 is patentable over the combination of Koyou and Wada
`
`because (1) the combination ofKoyou and Wada does not lead to the method of Claim 3, (2) the
`
`method of Claim 3 runs contrary to conventional wisdom in the art, and (3) the method of Claim
`
`3 provides unexpected results (see paragraph 6 of the Declaration of Joseph B. Bernstein, dated
`
`March 8, 2012 and submitted herewith [hereinafter, the "Bernstein Declaration"]).
`
`1.
`
`The Combination ofKoyou and Wada Does Not Lead to the Present Invention
`
`Two of the most significant features of Claim 3 of the '221 Patent are (i) the cut-link pad
`
`having substantially less thermal resistance per unit length than each of the first and second
`
`Page 4 of33
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`4
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`lines, and (ii) the width of the cut-link pad being at least ten percent greater than the width of
`
`each of the first and second electrically-conductive lines. Having both of these features in a cut(cid:173)
`
`link pad in a vertical fuse is particularly advantageous (see the Bernstein Declaration, paragraph
`
`7). In vertical fuse structures, the electrically-conductive lines are in a metal layer under and/or
`
`below the fuse pad (see the Bernstein Declaration, paragraph 35). In a vertical fuse, the fuse pad
`
`has an inner surface facing the substrate and an opposing outer surface facing away from the
`
`substrate, and the electrically-conductive lines extend from the inner surface into the substrate
`
`(see Claims 3, 17 and 26), and the fuse pad, the first and second electrically-conductive lines,
`
`and the underlying interconnection layers may be formed at different times and with different
`
`materials (see the Bernstein Declaration, paragraph 35). Vertical fuses have the advantage of
`
`being manufacturable using structures having the smallest possible dimensions (see the Bernstein
`
`Declaration, paragraph 33).
`
`The combination of Koyou and Wada does not lead to the present Claims 3 and 26
`
`because:
`
`(1)
`
`Koyou discloses a vertical fuse, but does not affirmatively disclose a cut-link pad
`
`having a width that is at least ten percent greater than the width of each of the first
`
`and second electrically-conductive lines (Claim 3 only),
`
`(2)
`
`Koyou does not disclose or suggest a cut-link pad having substantially less
`
`thermal resistance per unit length than each of the first and second lines,
`
`(3) Wada discloses a horizontal fuse, and therefore, does not cure the deficiencies of
`
`Koyou with regard to a cut-link pad having a width at least ten percent greater
`
`than the width of the electrically-conductive lines (Claim 3 only) and/or a cut-link
`
`pad having substantially less thermal resistance per unit length in a vertical fuse,
`
`and
`
`( 4)
`
`One of ordinary skill in the art would not combine features from the horizontal
`
`fuse of Wada with the vertical fuse of Koyou (see the Bernstein Declaration,
`
`paragraph 8).
`
`Page 5 of33
`
`5
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`A. Koyou Does Not Affirmatively Disclose or Suggest a Cut-link Pad Having a
`Width That is at Least Ten Percent Greater Than the Width of the Conductive
`Lines
`
`Koyou discloses three embodiments of vertical fuses as shown in FIGS. 1-3. The three
`
`embodiments are discussed below. Claim 3 of the '221 Patent is distinguished over each of these
`
`three embodiments (see the Bernstein Declaration, paragraph 9).
`
`Koyou discloses a fuse member (of length L) that can be disconnected by a laser beam,
`
`and interconnection layers 3a and 3b that are connected to the fuse member through contact
`
`holes 2a and 2b (see paragraph [0009], and FIG. 1(a) and 1(b) ofKoyou; shown below). Koyou
`
`also discloses that the length L of fuse member 1 is less than or equal to the illumination spot
`
`diameter D of the laser beam 5 (see paragraph 0010 of Koyou), and that the fuse member 1 is
`
`structured to be, at the largest, about the same size as the illumination spot diameter of laser
`
`beam 5 so as to minimize the thermal capacity by minimizing the volume of fuse member 1 (see
`
`paragraph 0012 ofKoyou; and the Bernstein Declaration, paragraph 10).
`
`FIG. 1(a) ofKoyou demonstrates that the width of the interconnection layers 3a and 3b is
`
`greater than the width of the material in the contact holes 2a and 2b. However, FIG. 1 also
`
`Page 6 of33
`
`6
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`clearly shows that the material in the contact holes 2a and 2b is part of the fuse member 1
`
`because the length L of the fuse member 1 includes the material in contact holes 2a and 2b, the
`
`material in the contact holes 2a and 2b is the same material as the material of the fuse (see the
`
`hatching in FIG. 1 (b)), the material in the fuse member 1 has a uniform thickness throughout its
`
`structure, and the laser directly irradiates material in the contact holes 2a and 2b (note the v(cid:173)
`
`shaped depression in the uppermost surface of fuse member 1 in the regions of contact holes 2a
`
`and 2b; see the Bernstein Declaration, paragraph 11 ). These facts clearly indicate that the same
`
`process (or series of process steps) forms fuse pad 1 and the material in the contact holes 2a-2b at
`
`the same time (see the Bernstein Declaration, paragraph 11). Therefore, since the material in
`
`contact holes 2a and 2b is part of the fuse, this material cannot be the "electrically-conductive
`
`lines" conductively bonded to the fuse, as recited in Claim 3 (see the Bernstein Declaration,
`
`paragraph 11 ).
`
`Consequently, m the embodiment of FIG. 1, the only structure that can be the
`
`"electrically-conductive lines" are interconnection layers 3a and 3b (see the Bernstein
`
`Declaration, paragraph 11 ). Koyou does not affirmatively disclose that the width of the fuse
`
`member 1 is at least ten percent greater than the width of interconnection layers 3a and 3b. In
`
`fact, the width of interconnection layers 3a and 3b is greater than the width of the contact holes
`
`2a and 2b. Therefore, the interconnection layers 3a and 3b do not necessarily constrain the flow
`
`of heat/thermal energy from the fuse member 1 (see the Bernstein Declaration, paragraph 12).
`
`Similarly, as shown in the embodiment of FIG. 2 of Koyou below, Koyou discloses a
`
`fuse member 10 having portions 1 Oa and 1 Ob, and underlying interconnection layers 11 a and 11 b
`
`below the fuse member 10 (see paragraph [0015] and FIG. 2 of Koyou). Koyou discloses that
`
`"the laser beam for disconnecting the fuse is selected to be approximately 5 )lm, where the length
`
`L of the fuse member 10 must be formed to be at most 5 )lm" (see paragraph [0016] and FIG. 2
`
`ofKoyou). Koyou further discloses that "as illustrated in FIG. 2, the cross-sectional areas of the
`
`individual portions 1 Oa and 1 Ob are selected to be smaller than the disconnection cross-sectional
`
`area of the fuse member 1 0," and that "by reducing the coverage rate of each of the conductive
`
`member portions 1 Oa and 1 Ob it is possible to achieve a relative increase in the thermal resistance
`
`Page 7 of33
`
`7
`
`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`of the contact portion relative to that of the fuse member 10" (see paragraph [0016] and FIG. 2 of
`
`Koyou; see also the Bernstein Declaration, paragraph 13).
`
`lHG.2l
`lU .. l:;>;:r:.~;:(t;-N.(i
`Dt.-\(~!J,A;.M
`Cs..<:oS~·$Etl1<.,">>-;:At
`'fB):~ C;:~n(' .. \._(
`Snu:M-'-T3~>~L'L)'" TH~ s:~t:cr~::~u: {)f'
`Ct~MK'Nf..~ .. ;;r { nr£ L~iR f\:~t.; H->
`,~ S;:·MK':ON:n~)Cfvt.:
`D£v3!:E A~ S.ET Ff<RTH ~N .-)f-iRST E>;.-\.bt.::N....5: or EM&:.-:>mM~:~.:r
`l~f:f.:Gf<"fJf~.:;r; '3 0 'fB£ ~fSs-.."1 f~\'~.':-..'1'~0~·;
`
`FIG. 2 of Koyou also clearly demonstrates that the length L of fuse member 10 includes
`
`the portions 1 Oa and 1 Ob and that portions 1 Oa and 1 Ob are completely within the laser spot
`
`diameter D (i.e., L:::; D; see the Bernstein Declaration, paragraph 14). Therefore, it is also clear
`
`that portions lOa and lOb of this embodiment are part o((use member 10 and are not "first and
`
`second electrically-conductive lines" as recited in Claim 3 (see the Bernstein Declaration,
`
`paragraph 14).
`
`Furthermore, Koyou does not affirmatively disclose that the width of fuse member 10 is
`
`at least 10% greater than the width of interconnection layers 11 a and 11 b (see the Bernstein
`
`Declaration, paragraph 15). Therefore, the interconnection layers 11a and 11 b do not necessarily
`
`constrain the flow of heat and/or thermal energy from the fuse member 10 (see the Bernstein
`
`Declaration, paragraph 15).
`
`In the embodiment of FIG. 3 of Koyou below, Koyou discloses a fuse member 20,
`
`contact holes 21 a and 21 b and interconnection layers 22a and 22b. The individual contact holes
`
`21 a and 21 b are connected to the fuse member 20 and to the underlying connection layers 22a
`
`and 22b using a "buried contact structure." The buried contact structure makes it possible to
`
`select material properties for the electrically conductive material buried within the contact holes
`
`Page 8 of33
`
`8
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`to be different from the material of fuse 20 (see paragraph [0020] and FIG. 3 of Koyou; see also
`
`the Bernstein Declaration, paragraph 16).
`
`{f-lG.3)
`l:_j_~.ss·:-;: .. ) n~..;:c,;
`n~t\.l:.'":R/..M
`CR:O$~.--Sr:r:·no~~-·\.t
`rH£.
`T:...::"f.
`S;:}.if:"M.·\ r::c.'\U.)'
`(J.~rf~C~L
`ST::::.uc~~~-
`of-
`.-\ SE~~tiX:-kf$:.X:f'-)R
`C0MfO~f-~1:l {-!~31: 1.ASE~ Ft~~r:) 1:.~
`.A.. SEco:,:£;. E .. 'lt.o.\El.-!P.tt: o.~
`t'X:·.,,..I(.F. As.
`.S.Fr f-t):~:n{ ~N:
`E~~~~c·t•ter.-rt~NT .·\co:.,~:_l!.UJ:~;~·> TO tHE PRf.?;E:-..=-r J::-.:v&-....:-r3:~:t~~
`
`However, Koyou is silent with regard to the relative widths of the fuse member 20 and
`
`the material filling each of the contact holes 21a and 21b (see the Bernstein Declaration,
`
`paragraph 17). Thus, Koyou does not affirmatively disclose that the width of the cut-link pad is
`
`at least ten percent greater than the width of each of the first and second electrically-conductive
`
`lines (see the Bernstein Declaration, paragraph 17).
`
`At the time of Koyou' s publication, line widths of 1.1-1.3 ~-tm in the uppermost layer of
`
`metal were not uncommon (see the Bernstein Declaration, paragraph 18, and Exhibits B and C
`
`attached thereto ["Construction Analysis of the Lattice ispLSI2032-180L CPLD" (Exhibit B\
`
`particularly the "Min metal 2 width" on p. 10 thereof, and "Construction Analysis of the
`
`Samsung KM44C4000J-7 16 Megabit DRAM" (Exhibit C), particularly the "Min metal2 width"
`
`on p. 11 thereof]). Also, it was not uncommon for the vias between the uppermost layer of metal
`
`and the next layer of metal therebelow in these devices to have a width of 1.0 - 1.2 ~-tm (see the
`
`Bernstein Declaration, paragraph 18, "Min via" on p. 10 of Exhibit B, and "Min via (metal2-to(cid:173)
`
`metal 1 )" on p. 11 of Exhibit C). Thus, while the uppermost layer of metal in the Lattice
`
`1 Patentees' undersigned representatives apologize for an oversight in the Patent Owners' Statement filed on August
`12, 2011. Although the Lattice Construction Analysis was intended to be submitted as Exhibit A to the Patent
`Owners' Statement, Patentees' undersigned representatives inadvertently submitted a Construction Analysis for a
`Chip Express programmable gate array.
`
`Page 9 of33
`
`9
`
`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`ispLSI2032-180L CPLD was arguably 10% wider than the vias connected thereto (1.1 )liD vs.
`
`1.0 )liD), the uppermost layer of metal in the Samsung KM44C4000J-7 16 Megabit DRAM was
`
`not (i.e., [1.3- 1.2] I 1.2 = 8.3%). Thus, the width of the fuse member 20 disclosed in FIG. 3 of
`
`Koyou is not necessarily at least ten percent greater than the width of the material filling each of
`
`the contact holes 21 a and 21 b (see the Bernstein Declaration, paragraph 18).
`
`B.
`
`Koyou Does Not Disclose or Suggest a Cut-link Pad Having Substantially Less
`Thermal Resistance Per Unit Length Than the Electrically-Conductive Lines
`
`FIG. l(a) of Koyou shows that the width of the interconnection layers 3a and 3b is
`
`greater than the width of the contact holes 2a and 2b. Since the material in the narrow contact
`
`holes 2a and 2b is part of the fuse, and at least part of the material in contact holes 2a and 2b is
`
`irradiated by the laser, the portions of the fuse pad 1 that are in the contact holes 2a and 2b have
`
`a thermal resistance that is greater than the thermal resistance of the interconnection layers 3a
`
`and 3b, if the material of the interconnection layers 3a and 3b is the same as that of the fuse
`
`member 1, including the material in the contact holes 2a and 2b (see the Bernstein Declaration,
`
`paragraph 19). Thus, fuse member 1 of Koyou does not have substantially less thermal
`
`resistance per unit length than interconnection layers 3a and 3b (see the Bernstein Declaration,
`
`paragraph 19).
`
`As illustrated in FIG. 2 of Koyou, the cross-sectional areas of the individual portions 1 Oa
`
`and 1 Ob are selected to be smaller than the disconnection cross-sectional area of the fuse member
`
`10. By reducing the coverage rate of each of the conductive member portions lOa and lOb, it is
`
`possible to achieve a relative increase in the thermal resistance of the contact portion relative to
`
`that of the fuse member 10. (See paragraph [0016] and FIG. 2 of Koyou.) However, as the
`
`thermal resistance of the portions 1 Oa and 1 Ob are increased, the thermal resistance of fuse
`
`member 10 is likewise increased, since portions 1 Oa and 1 Ob are part ofthe fuse (see discussion
`
`ofKoyou in subsection lA above; also see the Bernstein Declaration, paragraph 20).
`
`Koyou discloses that the portions 1 Oa and 1 Ob in this embodiment are formed of the same
`
`material as the fuse member 10. However, portions lOa and lOb may also be formed from other
`
`Page 10 of33
`
`10
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
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`materials, so long as they are electrically-conductive materials. Koyou states that "[i]n this case,
`
`electrically conductive materials should be selected that have thermal resistances that are as
`
`great as possible (see paragraph [0017] of Koyou, emphasis added; also see the Bernstein
`
`Declaration, paragraph 21). Consequently, because portions lOa and lOb are part of the fuse
`
`member 10, the fuse member 10 in FIG. 2 ofKoyou would have a correspondingly high thermal
`
`resistance (see the Bernstein Declaration, paragraph 21).
`
`Furthermore, it is clear from FIG. 3 of Koyou that the width of the contact holes (vias)
`
`2la and 2lb (designated as "WV" below) is much greater than the thickness of the fuse member
`
`20 (designated as "TF" below; see the Bernstein Declaration, paragraph 22). Based on
`
`measurements ofthe relative dimensions ofWV (e.g., about 7.8 mm in the diagram below) and
`
`TF (e.g., about 4.7 mm in the diagram below) in FIG. 3 ofKoyou, the thickness TF ofthe fuse
`
`member 20 is approximately 60% of the width (WV) of the material in the contact holes 21 a and
`
`2lb (i.e., TF/WV:::: 0.6; see the Bernstein Declaration, paragraph 22).
`
`TF
`
`r·-·.-.".·.··'="~·.~···'·'=~' ~·"~w~.~••.ow.~·-~·~··---"~
`
`( Rrm >H-rra)
`
`!
`
`L(;iO)
`
`:
`
`20(RrM·l)
`
`wv
`
`Although Koyou does not disclose the width of the fuse member 20 or the width of the
`
`contact holes 21 a and 21 b, based on (i) dimensions for these parameters that were arguably
`
`considered "state of the art" at the time of Koyou' s publication, (ii) the approximate ratio of the
`
`Page 11 of33
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`11
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`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
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`thickness of the fuse member 20 to the width of the contact holes 21 a and 21 b as calculated from
`
`FIG. 3 of Koyou, and (iii) the thermal conductivity of the most likely or most commonly used
`
`metals for the fuse member 20 and the material in the contact holes 21a and 21b in FIG. 3 of
`
`Koyou, the fuse member 20 of Koyou does not necessarily have less thermal resistance per unit
`
`length than the material in the contact holes 21 a and 21 b, much less substantially less thermal
`
`resistance per unit length (see the Bernstein Declaration, paragraph 23).
`
`For example, at the time of Koyou's publication, a width of 1.1 )lm for the uppermost
`
`metal layer and a width of 1.0 )lm for vias was not unusual (see the Bernstein Declaration,
`
`paragraph 24, and Exhibit B attached thereto, p. 10). Thus, based on the via width disclosed in
`
`Exhibit Band the ratio of fuse member thickness to via width calculated from FIG. 3 of Koyou,
`
`the thickness of the fuse member 20 is estimated to be 0.6 )lm (i.e., 1.0 )lm x 0.6, or 60%; see the
`
`Bernstein Declaration, paragraph 24). Koyou discloses that the fuse member 20 may be
`
`aluminum and the material filling the contact holes 21a and 21b may be tungsten (see paragraphs
`
`[0016] and [0021] of Koyou). Accordingly, based on the thermal conductivities of aluminum
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`(i.e., 235 W/m-°K) and tungsten (i.e., 170 W/m-°K), the relative thermal conductance per unit
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`length of (i) the fuse member 20 to (ii) the vias in contact holes 21a and 21 bin FIG. 3 of Koyou
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`is estimated to be 155 : 170 (i.e., [1.1 x 0.6 x 235] to [1.0 x 1.0 x 170]; see the Bernstein
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`Declaration, paragraph 24). Thus, based on the widths of the uppermost metal layer and the
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`uppermost via disclosed in Exhibit B and the ratio of the thickness of fuse member 20 to the
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`width of the vias in the contact holes 21a and 21b in FIG. 3 of Koyou, the estimated thermal
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`conductance per unit length of the fuse member 20 is less than the estimated thermal
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`conductance per unit length of the material filling the contact holes 21 a and 21 b (i.e., the
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`estimated thermal resistance per unit length of the fuse member 20 of FIG. 3 ofKoyou is greater
`
`than the estimated thermal resistance per unit length of the material filling the contact holes 21 a
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`and 21b; see the Bernstein Declaration, paragraph 24).
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`Likewise, using the dimensions of the uppermost metal layer and the uppermost vias in
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`Exhibit C (i.e., 1.3 )lm and 1.2 )lm respectively; see p. 11 of Exhibit C), the estimated relative
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`thermal conductance per unit length of the fuse member 20 to the material filling the contact
`
`Page 12 of33
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`12
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`

`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 901011,607
`
`holes 21a and 21b in FIG. 3 ofKoyou is 220: 245 (i.e., [1.3 x (1.2 x 0.6) x 235] to [1.2 x 1.2 x
`
`170]; see the Bernstein Declaration, paragraph 25). Thus, based on the dimensions disclosed in
`
`Exhibit C, the estimated thermal resistance per unit length of the fuse member 20 is greater than
`
`the estimated thermal resistance per unit length of the material filling the contact holes 21 a and
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`21 b (see the Bernstein Declaration, paragraph 24 ). Therefore, it cannot be said that the thermal
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`resistance per unit length of the fuse member 20 in FIG. 3 of Koyou is necessarily less than the
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`thermal resistance per unit length of the material in the contact holes 21 a and 21 b, much less
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`substantially less than the thermal resistance per unit length of the material in the contact holes
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`21a and 21b (see the Bernstein Declaration, paragraph 25).
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`As a result, even though Koyou discloses that the material filling each of the contact
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`holes 21 a and 21 b has a higher thermal resistance than the fuse member 20 (see paragraph
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`[0022]), it is not necessarily true that the material filling each of the contact holes 21 a and 21 b
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`has a higher thermal resistance per unit length than the fuse member 20, because the ratio of (i)
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`the cross-sectional area of the material filling each of the contact holes 21a and 21 b to (ii) the
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`cross-sectional area of the fuse member 20 (i.e., [1.0 x 1.0] I [1.1 x 0.6] = 1.51 based on the
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`disclosure of Exhibit B or [1.2 x 1.2] I [1.3 x 1.2 x 0.6] = 1.54 based on the disclosure of Exhibit
`
`C) may be greater than the ratio of (i') the thermal conductance of the fuse member 20 to (ii') the
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`thermal conductance of the material filling each of the contact holes 21 a and 21 b (i.e., [235/170]
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`= 1.38 based on an aluminum fuse member and tungsten in the contact holes; see the Bernstein
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`Declaration, paragraph 25). Thus, even though Koyou discloses that the material filling each of
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`the contact holes 21 a and 21 b has a higher thermal resistance than the fuse member 20
`
`(paragraph [0022] ofKoyou), it is not necessarily true that the material filling each of the contact
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`holes 21 a and 21 b has a higher thermal resistance per unit length than the fuse member 20 (see
`
`the Bernstein Declaration, paragraph 26).
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`The fuse structures recited in Claim 3 retain thermal energy more effectively than the
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`fuse structures of Koyou because (1) the conductive lines have a substantially higher thermal
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`resistance per unit length than the fuse pad, thereby restricting the dissipative heat transfer into
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`the conductive lines and improving the probability of a fuse being successfully cut by laser
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`Page 13 of33
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`13
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`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`irradiation, and (2) the fuse pad has a width at least 10% greater than the conductive lines,
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`thereby increasing the absorption of laser radiation and decreasing the probability of damage to
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`the underlying structures (see the Bernstein Declaration, paragraph 27).
`
`C.
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`Wada Does Not Cure the Deficiencies of Koyou With Regard to the Two Most
`Significant Features of Claim 3
`
`As explained below, Wada does not cure the deficiencies of Koyou with regard to a cut(cid:173)
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`link pad having (1) at least a ten percent greater width and (2) substantially greater thermal
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`conductivity per unit length than the first and second electrically-conductive lines bonded thereto
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`in a vertical fuse (i.e., a fuse wherein the electrically-conductive cut-link pad has an inner surface
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`facing the substrate and an opposing outer surface facing away from the substrate, the first and
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`second electrically-conductive lines extending from the inner surface into the substrate; see the
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`Bernstein Declaration, paragraph 28.)
`
`In a first embodiment, Wada discloses a redundancy fuse 1 formed of polysilicon,
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`polycide, aluminum or similar material having a fusing portion 1 a continuously provided
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`between non-fusing portions 1 b. Wada also discloses that the width of the non-fusing portions
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`1 b is approximately 1 )lm and that the size of the fusing portion 1 a is set to be closer to the area
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`of the irradiation region 4 of the laser light. For example, if the irradiation region 4 of the laser
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`light is set to be an area of a circle with the diameter of 3 )lm, the area of the fusing portion 1 a is
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`set to be approximately 60% thereof, being a square with one side of2 )lm (see paragraph [0010]
`
`and FIG. 1 of Wada). Wada further discloses that the fusing portion of the redundancy fuse in
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`this first embodiment is closer to the area of the irradiation region 4 of the laser light so that the
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`overlapping area of the irradiation region 4 and the fusing portion 1 a is larger than in a
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`conventional configuration, and the amount of laser light leaking to a lower layer is reduced (see
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`paragraphs [0012] and [0013] ofWada; see also the Bernstein Declaration, paragraph 29.)
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`In a second embodiment, Wada discloses that a redundancy fuse 5 is formed of a fusing
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`portion 5a positioned in the center of non-fusing portions 5b continuously provided on both ends
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`of the fusing portion 5a, in which a region 6 continuously provided on the both ends of the fusing
`
`Page 14 of33
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`14
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`

`Atty. Docket No. MIT-7581L-RX1
`U.S. Patent No.: 6,057,221
`
`Control No.: 90/011,607
`
`portion has a width that is smaller than the width of the periphery so that the heat resistance is
`
`increased (see paragraph [0013] and FIG. 2 of Wada). In this embodiment, the widths of the
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`fusing portion 5a and the non-fusing portions 5b, excluding the region 6 are approximately 1 )lm
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`and a width of the region 6 is approximately 0.5 )lm. Accordingly, the heat resistance of the
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`region 6 is higher than with a redundancy fuse with a uniform width. Thus, the escape of heat
`
`generated in the fusing portion 5a is reduced (see paragraphs [0014] and [0015] of Wada; see
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`also the Bernstein Declaration, paragraph 30).
`
`Wada further discloses a third embodiment in which the heat resistance of the region 6 is
`
`increased by providing slits 7 so as to increase the heat resistance of the region 6 compared to the
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`periphery (see paragraph [0016] and FIG. 3 of Wada; see also the Bernstein Declaration,
`
`paragraph 31 ).
`
`The fuse structures disclosed in Wada are essentially horizontal structures, because the
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`fusing portion and the non-fusing portions are formed in the same layer of the device and from
`
`the same material (see the Bernstein Declaration, paragraph 32). Wada simply discloses (i)
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`increasing the width of the fusing portion so that the energy of the laser light can be effectively
`
`utilized, and (ii) decreasing the width of the material in the regions 6 (either by narrowing the
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`entire width as in FIG. 2, or creating a slit as in FIG. 3) so as to increase the heat resistance of the
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`regions 6, and thereby reduce the escape of heat generated in the fusing portion (see the
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`Bernste