DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Objections
Claims 1, 9, 10, 13, 17 and 18 are objected to because of the following informalities:
Claim 1, line 6, recites "and and"; one "and" should be deleted.
Claims 1 and 10 recite "one of the electrodes of plurality of electrodes"; "of plurality of electrodes" should read "of the plurality of electrodes."
Claim 9, line 1, recites "Claim 1¸" with a cedilla in place of the comma.
Claim 13, line 1, recites "Claim 10." with a period in place of the comma.
Claim 17, line 1, recites "in electrically contact with"; "electrically" should read "electrical."
Claim 18, line 2, recites "the bottom portion of semiconductor structure"; "of semiconductor structure" should read "of the semiconductor structure."
Appropriate correction is required.
Specification
The disclosure is objected to because of the following informalities: in ¶0045, the cavities are referred to by three different reference numerals; in ¶0052, the die stack is referred to by two different reference numerals; in ¶0031, the semiconductor structure is referred to as a "semiconductor substrate"; and in ¶0049, "BEOL" appears as "BEO." Appropriate correction is required.
Claim Interpretation
The claims are given their broadest reasonable interpretation consistent with the specification. MPEP 2111. The following constructions are applied throughout this action.
"Vapor chamber heat spreader." Applicant's specification describes a vapor chamber heat spreader as a planar heat pipe that spreads heat by evaporation and condensation of a working fluid within a sealed cavity (¶0018). The term is therefore construed to encompass any planar, sealed two-phase heat-transfer structure having a vapor region, including devices described in the art as flat or planar heat pipes.
"Semiconductor structure." Applicant's specification states that the semiconductor structure is composed of at least one semiconductor material and may be formed from one or more semiconductor substrates (¶0023, ¶0025). The term is construed to require that the structure enclosing the vapor core comprise a semiconductor material; it does not require a single-crystal body, a particular semiconductor, or that the structure contain active devices.
"Vapor core." Construed as the region of the interior of the structure occupied by vapor of the working fluid during operation (applicant's specification, ¶0018–¶0019). The claims do not require a wick, a working fluid, or a particular geometry of the vapor region.
"Beneath," "above," "bottom portion," "top portion." Applicant's specification states that these spatial terms are relative to the orientation shown in the drawings and that an element described as beneath or under another may have one or more intervening elements between them (¶0015). "Beneath the vapor core" and "above the vapor core" therefore require only that the layer lie on the respective side of the vapor core, not direct contact with it. "Bottom portion" is construed as the part of the semiconductor structure on the side of the vapor core that faces the heat source (¶0022, ¶0032).
"Hydrophobic layer." Applicant's specification describes the hydrophobic layers as composed of hydrophobic, water-resistant polymers (¶0025). The term is construed as a layer whose exposed surface is hydrophobic with respect to the working fluid. The claims do not specify a contact angle, a material, or a thickness.
"Electrode." Claim 1 recites electrodes structurally — located in the bottom portion and in electrical contact with a via structure — and recites no function for them. The electrowetting operation described in applicant's specification (¶0020–¶0021) is not claimed in claim 1; claim 19 alone recites that the electrodes are powered. "Electrode" is therefore construed as an electrically conductive element positioned as claimed, whatever its intended use.
"Electrically conductive via structure … extends entirely through the bottom portion." Construed as a conductive element passing from one face of the bottom portion to the opposite face (applicant's specification, ¶0032; FIG. 2). "In electrical contact with, and located beneath, one of the electrodes" requires a conductive path between the via structure and the electrode and that the via structure lie on the far side of the electrode from the vapor core; it does not require the via structure and the electrode to be of the same material (claims 5–6 address that) or to be coextensive.
"Attached to" (claim 10). Construed as physically joined, directly or through an intervening layer such as a thermal interface or bonding material (applicant's specification, ¶0052).
No claim recites "means" or a non-structural placeholder term coupled with functional language, and no claim is interpreted under 35 U.S.C. 112(f).
Claim Rejections – 35 U.S.C. 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claims 1–3, 5–7, 10–12, 14 and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Bahadur et al. (US 2017/0074603 A1, "Bahadur") in view of Oprins et al. (US 2011/0304987 A1, "Oprins").
Regarding claim 1, Bahadur discloses a vapor chamber heat spreader (electrowetting heat pipe 300, FIGS. 3A–3B, ¶0020–0021, having a thin, "planar form factor," ¶0002, less than 2 mm thick with 0.25 mm top and bottom plates, ¶0023; applicant's specification at ¶0018 states that vapor chamber heat spreaders are planar heat pipes) comprising:
a vapor core present in an interior of a structure (vapor conduits 304 between lower plate 201B and upper plate 201A, FIGS. 2, 3A, ¶0021–0022; in the embodiment of ¶0026 no walls 307 separate the liquid and vapor regions, so the vapor occupies the interior between the plates);
a first hydrophobic layer located in the interior of the structure and beneath the vapor core (hydrophobic layer 206B covering lower plate 201B, FIG. 2, ¶0016);
a second hydrophobic layer located in the interior of the structure and above the vapor core (hydrophobic layer 206A covering upper plate 201A, FIG. 2, ¶0016); and
a plurality of electrodes located in a bottom portion of the structure (control electrodes 203A–203B on lower plate 201B, FIG. 2, ¶0015), voltage being supplied to individual electrodes "by a network of electrical bus bars and interconnects on the heat pipe bottom plate 201B," ¶0025.
Bahadur does not expressly disclose that the structure is a semiconductor structure, or a plurality of electrically conductive via structures located in the bottom portion, each in electrical contact with, and located beneath, one of the electrodes and extending entirely through the bottom portion.
Oprins discloses an electrowetting two-phase cooling device for an integrated circuit (¶0002, ¶0039) formed from a stack of silicon layers 1 (FIG. 1a, ¶0036; low-resistivity silicon, ¶0046; "semiconducting material," ¶0015), each carrying electrowetting electrodes 5 in an insulating layer 4 (FIG. 1b, ¶0036), in which electrodes are electrically contacted through vias 12, "preferably produced as 'Through silicon vias' or TSV's," extending entirely through the adjoining silicon layer (FIG. 2, ¶0037; vias 302, FIG. 9, ¶0069; copper vias 400 through the wafer, FIGS. 11A–12, ¶0071–0072), so that "each channel 3' can be actuated individually" (¶0037), as an alternative to routing the electrodes laterally to the periphery of the chip (¶0036).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to form Bahadur's plates 201A–201B of silicon and to supply Bahadur's lower-plate electrodes 203 through through-silicon vias extending entirely through lower plate 201B, as taught by Oprins, in order to actuate each electrode individually through vertical connections rather than the lateral bus-bar routing of Bahadur ¶0025, as Oprins teaches for electrowetting cooling devices fabricated in silicon and integrated with semiconductor chips (¶0036–0037). With the vias extending through the bottom plate from its outer face to the electrodes on its inner face, each via is beneath, and in electrical contact with, its electrode, and the resulting structure enclosing the vapor core is a semiconductor structure.
Regarding claim 2, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above. Bahadur further discloses that each of the electrodes of the plurality of electrodes is in direct physical contact with the first hydrophobic layer. Control electrodes 203A–203B on lower plate 201B are covered by dielectric layer 205B (FIG. 2, ¶0015–0016), and Bahadur states that the surface energy of dielectric layer 205 "will be low which will make dielectric layer 205 superhydrophobic" (¶0017), the layer being a polymer, oxide, ceramic, or other insulating material (¶0017). Dielectric layer 205B is thus itself a hydrophobic layer located in the interior of the structure beneath the vapor core, and it lies directly on electrodes 203 (FIG. 2). Bahadur further states that the separate hydrophobic layers 206 are not required (¶0018), so that in the embodiment without layers 206 the superhydrophobic dielectric layer 205B is the only hydrophobic layer on the lower plate and is the layer in direct physical contact with the electrodes. Applicant's specification describes the hydrophobic layers as hydrophobic polymers (¶0025); Bahadur's superhydrophobic polymer dielectric layer 205B falls within that description.
Regarding claim 3, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above. Bahadur further discloses a dielectric layer located between the first hydrophobic layer and the plurality of electrodes: lower plate 201B carrying control electrodes 203A–203B is covered by dielectric layer 205B and then by hydrophobic layer 206B (FIG. 2, ¶0015–0016), so that dielectric layer 205B lies between the electrodes 203 and the hydrophobic layer 206B. Bahadur describes dielectric layer 205 as a polymer, oxide, ceramic, or other insulating material ranging in thickness from nanometers to microns (¶0017).
Regarding claim 5, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above. Oprins further discloses that the electrical contacts of its silicon layers are formed by conformally plating copper contacts 314 over a sputtered seed layer in holes in the silicon substrate (FIG. 10A–10C, ¶0070), and that the vias 400 connecting the layers are copper, "the copper … protruding out of the wafer" (FIG. 11A, ¶0072). Oprins thus teaches copper as the electrically conductive metal for both the contacts through the silicon and the vias.
Bahadur in view of Oprins does not expressly state that the plurality of electrodes and the plurality of electrically conductive via structures are composed of a same electrically conductive metal or electrically conductive metal alloy. However, Oprins teaches copper as the conductor for the plated contacts and the through-wafer vias (¶0070, ¶0072), and Bahadur places no limitation on the composition of electrodes 203 (¶0015). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to form the electrodes 203 of the modified Bahadur heat pipe from the same copper used for the through-silicon vias of Oprins, in order to form the electrode and the via in a single plating step (Oprins ¶0070, conformal plating of contacts over the seed layer) and to avoid a dissimilar-metal junction between the electrode and the via that feeds it. Selecting a known conductor already used for the via for the electrode it contacts is a selection of a known material based on its suitability for its intended use, which supports a prima facie case of obviousness. MPEP 2144.07.
Regarding claim 6, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above. Oprins further discloses that the electrically active elements of each silicon layer are contacted by a metal contact 203 that is deposited and patterned on the layer, for which "aluminum can be used" (¶0057, FIG. 8b), and that the vias 400 connecting the layers are copper (¶0071–0072, FIG. 11A). Oprins further discloses that the layers themselves may be formed of low-resistivity silicon so that no separate electrodes are present (¶0015, ¶0046, ¶0052), the doped silicon layer serving as the electrically conductive electrode. Oprins thus teaches an electrically conductive electrode element composed of a first electrically conductive material (aluminum, ¶0057; or doped silicon, ¶0015) and a via structure composed of a second electrically conductive material that is compositionally different from the first electrically conductive material (copper, ¶0072).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to form the electrodes 203 of the modified Bahadur heat pipe of aluminum, as Oprins teaches for the patterned metal contacts on its silicon layers (¶0057), and the through-silicon vias of copper, as Oprins teaches for its through-wafer vias (¶0070–0072), since Oprins teaches this pairing of a patterned aluminum contact layer with plated copper vias in the same electrowetting cooling device (¶0057, ¶0070–0072), and use of a known material pairing for its known purpose supports a prima facie case of obviousness. MPEP 2144.07.
Regarding claim 7, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above. In Bahadur's FIG. 2 embodiment, upper plate 201A is covered by a single grounded electrode 204, dielectric layer 205A, and hydrophobic layer 206A (¶0016), so that hydrophobic layer 206A is not in direct physical contact with the plate. Bahadur further discloses, however, that dielectric layer 205 has a low surface energy that makes it superhydrophobic (¶0017), and that the separate hydrophobic layers 206 are not required (¶0018), so that superhydrophobic dielectric layer 205A may itself serve as the hydrophobic layer above the vapor core. Oprins discloses that where a layer of the electrowetting device is made of highly doped silicon, the layer "can act themselves as an electrode" and separate metal electrodes "are not strictly necessary," which "greatly simplifies the fabrication of the cooling device" (¶0036; see also ¶0015).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, in the modified Bahadur heat pipe whose plates are formed of silicon as taught by Oprins, to form upper plate 201A of highly doped silicon serving as the grounded electrode and to omit the separate electrode 204, as Oprins teaches (¶0036), in order to simplify fabrication, and to apply the superhydrophobic dielectric layer 205A directly to that plate (Bahadur ¶0016–0018). In the resulting structure the second hydrophobic layer (superhydrophobic dielectric 205A) is in direct physical contact with a top portion of the semiconductor structure (doped silicon upper plate 201A).
Regarding claim 10, Bahadur discloses an assembly comprising a vapor chamber heat spreader (electrowetting heat pipe 300, FIGS. 3A–3B, ¶0020–0021, having a thin, "planar form factor," ¶0002, less than 2 mm thick with 0.25 mm top and bottom plates, ¶0023; applicant's specification at ¶0018 states that vapor chamber heat spreaders are planar heat pipes) that receives heat from a heat source at its evaporator end (¶0012, FIG. 1: heat moved from a hot source at evaporator end 101 by evaporation of the working fluid), the vapor chamber heat spreader comprising:
a vapor core present in an interior of a structure (vapor conduits 304 between lower plate 201B and upper plate 201A, FIGS. 2, 3A, ¶0021–0022; in the embodiment of ¶0026 no walls 307 separate the liquid and vapor regions, so the vapor occupies the interior between the plates);
a first hydrophobic layer located in the interior of the structure and beneath the vapor core (hydrophobic layer 206B covering lower plate 201B, FIG. 2, ¶0016);
a second hydrophobic layer located in the interior of the structure and above the vapor core (hydrophobic layer 206A covering upper plate 201A, FIG. 2, ¶0016); and
a plurality of electrodes located in a bottom portion of the structure (control electrodes 203A–203B on lower plate 201B, FIG. 2, ¶0015), voltage being supplied to individual electrodes "by a network of electrical bus bars and interconnects on the heat pipe bottom plate 201B," ¶0025.
Bahadur does not expressly disclose a microelectronic device attached to the vapor chamber heat spreader, that the structure is a semiconductor structure, or a plurality of electrically conductive via structures located in the bottom portion, each in electrical contact with, and located beneath, one of the electrodes and extending entirely through the bottom portion.
Oprins discloses an electrowetting two-phase cooling device (¶0039) for cooling the surface of a semiconductor device such as an integrated circuit (¶0002, ¶0012), the cooling device being formed from a stack of silicon layers 1 (FIG. 1a, ¶0036; low-resistivity silicon, ¶0046; "semiconducting material," ¶0015), each carrying electrowetting electrodes 5 in an insulating layer 4 (FIG. 1b, ¶0036), wherein "the layer stack is glued to the chip 10 to be cooled" (¶0036) — i.e., a microelectronic device attached to the cooling device — and wherein electrodes are electrically contacted through vias 12, "preferably produced as 'Through silicon vias' or TSV's," extending entirely through the adjoining silicon layer (FIG. 2, ¶0037; vias 302, FIG. 9, ¶0069; copper vias 400 through the wafer, FIGS. 11A–12, ¶0071–0072), so that "each channel 3' can be actuated individually" (¶0037), as an alternative to routing the electrodes laterally to the periphery of the chip (¶0036).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to attach the integrated circuit chip of Oprins to the evaporator end of Bahadur's heat pipe as the heat source, since Oprins teaches that electrowetting two-phase coolers are used for cooling integrated circuits and are attached to the chip to be cooled (¶0012, ¶0036), and Bahadur's heat pipe requires a heat source at its evaporator (¶0012). It would further have been obvious to form Bahadur's plates 201A–201B of silicon and to supply Bahadur's lower-plate electrodes 203 through through-silicon vias extending entirely through lower plate 201B, as taught by Oprins, in order to actuate each electrode individually through vertical connections rather than the lateral bus-bar routing of Bahadur ¶0025, as Oprins teaches for electrowetting cooling devices fabricated in silicon and attached to semiconductor chips (¶0036–0037). With the vias extending through the bottom plate from its outer face to the electrodes on its inner face, each via is beneath, and in electrical contact with, its electrode, and the resulting structure enclosing the vapor core is a semiconductor structure.
Regarding claim 11, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, and Bahadur further discloses that each of the electrodes of the plurality of electrodes is in direct physical contact with the first hydrophobic layer, for the reasons given for claim 2 (¶0015–0018, FIG. 2).
Regarding claim 12, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, and Bahadur further discloses that the vapor chamber heat spreader comprises a dielectric layer located between the first hydrophobic layer and the plurality of electrodes, for the reasons given for claim 3 (¶0015–0017, FIG. 2).
Regarding claim 14, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, and the second hydrophobic layer is in direct physical contact with a top portion of the semiconductor structure for the reasons given for claim 7 (Bahadur ¶0016–0018; Oprins ¶0015, ¶0036).
Regarding claim 18, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above. Oprins further discloses that the silicon layer stack of the cooling device "is glued to the chip 10 to be cooled" (¶0036), and that layers of the device are bonded to one another through an adhesive polymer 401 applied over the protruding copper vias (¶0072, FIG. 11B). In the assembly of claim 10 as set forth above, the integrated circuit of Oprins is attached to the lower plate 201B of the modified Bahadur heat pipe, through which the through-silicon vias extend; attaching it by gluing, as Oprins teaches for attaching its silicon cooling device to the chip (¶0036), results in the microelectronic device being bonded to the bottom portion of the semiconductor structure of the vapor chamber heat spreader.
Claims 4, 8, 13 and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Bahadur in view of Oprins, and further in view of Cai et al. (US 2011/0284188 A1, "Cai").
Regarding claim 4, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above, but does not expressly disclose a support pillar present in the vapor core.
Cai discloses a vapor chamber heat spreader 700 (FIG. 7, ¶0039) fabricated from silicon substrates by wafer fabrication techniques (¶0032, ¶0038, ¶0041), in which a top substrate 704 and a bottom substrate 706 having complementary chamber portions collectively define a vapor chamber 716, and in which a top substrate pillar 718 formed from the top substrate is bonded to a lower substrate pillar 720 extending from the lower substrate "to provide structural support for the heat spreader 700" (¶0039). The pillars are located within the vapor chamber 716, including at its center (¶0041, FIG. 8), and a pattern of spaced pillars may be used (¶0041). The bonded pillars 718/720 are a support pillar present in the vapor core.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to provide a support pillar between the lower and upper plates of the heat pipe of Bahadur as modified by Oprins, as taught by Cai, in order to provide structural support for the sealed, thin-walled vapor chamber (Cai ¶0039; Bahadur ¶0023, 0.25 mm plates), Cai teaching that such pillars are formed from the silicon substrates themselves in wafer-fabricated vapor chambers of the type resulting from the Bahadur–Oprins combination (¶0038–0039, ¶0041).
Regarding claim 8, Bahadur in view of Oprins teaches the vapor chamber heat spreader of claim 1 as set forth above, in which the lower and upper plates are formed of silicon as taught by Oprins, but does not expressly disclose that the bottom portion of the semiconductor structure is composed of a first semiconductor substrate and the semiconductor structure has a top portion composed of a second semiconductor substrate, and the first semiconductor substrate is in direct physical contact with the second semiconductor substrate.
Cai discloses a vapor chamber heat spreader 700 (FIG. 7) in which a bottom substrate 706 and a top substrate 704, each a silicon wafer (¶0032, ¶0038, ¶0042: "top and bottom substrates … alternatively referred to as top and bottom wafers"), have complementary recessed chamber portions that together define vapor chamber 716 (FIG. 7, ¶0039). A top substrate pillar 718 formed from the top substrate is bonded to a lower substrate pillar 720 extending from the lower substrate (FIG. 7, ¶0039), so that the two silicon substrates are in direct physical contact with one another at the bonded pillars. Cai further teaches that silicon substrates of the heat spreader may be joined by diffusion bonding (¶0045; ¶0043: bonding "by applying a suitable temperature-time-pressure cycle under vacuum"), which joins the silicon surfaces directly without an intervening layer.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to form the bottom and top portions of the modified Bahadur heat pipe as first and second silicon substrates with recessed chamber portions and to bond them directly to one another, as taught by Cai, in order to define and seal the vapor chamber using common wafer fabrication techniques (Cai ¶0041) and to provide the structural support of pillars formed from the substrates themselves (Cai ¶0039), the silicon plates of the Bahadur–Oprins combination being the same kind of wafer-fabricated silicon vapor-chamber walls that Cai describes.
Regarding claim 13, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, but does not expressly disclose a pillar structure present in the vapor core. Cai discloses bonded pillars 718/720 within vapor chamber 716 (FIG. 7, ¶0039, ¶0041), which are a pillar structure present in the vapor core, and it would have been obvious to include them in the assembly of claim 10 for the reasons given for claim 4.
Regarding claim 15, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, and Cai teaches a bottom portion composed of a first semiconductor substrate in direct physical contact with a top portion composed of a second semiconductor substrate (FIG. 7, ¶0039, ¶0042–0043, ¶0045) for the reasons given for claim 8, which apply equally to the assembly of claim 10.
Claims 9 and 16 are rejected under 35 U.S.C. 103 as being unpatentable over Bahadur in view of Oprins and Cai, and further in view of Tung et al. (US 2021/0375766 A1, "Tung").
Regarding claim 9, Bahadur in view of Oprins and Cai teaches the vapor chamber heat spreader of claim 1 in which the bottom portion is composed of a first silicon substrate 706 and the top portion is composed of a second silicon substrate 704 that are bonded together to define the vapor chamber (Cai FIG. 7, ¶0039, ¶0042), as set forth for claim 8. Cai further teaches that the top and bottom substrates may be joined through an intervening dielectric bonding structure rather than directly, disclosing a glass center layer between the silicon substrates joined by anodic bonding or glass frit bonding (¶0039; FIGS. 14–15, ¶0045). Bahadur, Oprins, and Cai do not expressly disclose that the first semiconductor substrate is spaced apart from the second semiconductor substrate by a dielectric-to-dielectric bonded structure.
Tung discloses bonding a first semiconductor device having a first semiconductor substrate 110 and a first surface dielectric layer 120 to a second semiconductor device having a second semiconductor substrate 210 and a second surface dielectric layer 220 (FIGS. 15–16, ¶0052–0053), by pressing the surface dielectric layers together and annealing so that "the surface dielectric layers 120 and 220 are bonded to each other" through Si–O–Si fusion bonds (¶0055–0056), the two semiconductor substrates thereby being spaced apart from one another by the bonded pair of dielectric layers 120/220. Tung teaches that the annealing improves bonding strength (¶0056) and that the bond is formed at wafer level using standard fabrication (¶0056: the stacked device is then sawed into packages).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to join the first and second silicon substrates of the modified Bahadur heat pipe through a dielectric-to-dielectric fusion bond between surface dielectric layers on each substrate, as taught by Tung, in place of, or as the specific form of, the intervening dielectric bonding structure that Cai already contemplates between its silicon substrates (¶0039, ¶0045), in order to obtain a strong, hermetic wafer-level bond between two semiconductor substrates by a known semiconductor bonding process (Tung ¶0056), Cai teaching that its heat spreader is made by common wafer fabrication techniques (¶0041).
Regarding claim 16, Bahadur in view of Oprins and Cai teaches the assembly of claim 10 with a bottom portion composed of a first semiconductor substrate and a top portion composed of a second semiconductor substrate (Cai FIG. 7, ¶0039, ¶0042), and Tung teaches spacing two semiconductor substrates apart by a dielectric-to-dielectric bonded structure (FIGS. 15–16, ¶0052–0056) for the reasons given for claim 9, which apply equally to the assembly of claim 10.
Claims 17 and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Bahadur in view of Oprins, and further in view of Bahadur et al. (US 2008/0047701 A1, "Bahadur '701").
Regarding claim 17, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, in which each electrode 203 on the lower plate is fed by a through-silicon via extending entirely through the lower plate to its outer face, the face to which the microelectronic device is attached, and Oprins teaches that the electrowetting device comprises or is "connectable to means for applying a voltage to the electrodes" (¶0012) and that its copper vias 400 protrude from the wafer surface for bonding to the adjoining layer (¶0072, FIG. 11A). Bahadur in view of Oprins does not expressly disclose that the microelectronic device is in electrical contact with each electrically conductive via structure of the plurality of electrically conductive via structures.
Bahadur '701 discloses an electrowetting heat spreader for a microelectronic chip 22 in which the control electrodes 24 are individually addressed and connected to electrical interconnects (FIG. 2, ¶0026), in which the device "utilizes a controller, which can be the chip being cooled," to apply the actuation voltages to the electrodes (¶0019; ¶0027: voltage applied to electrode 24 "by the controller"), and in which the lower plate 30 of the spreader may be the upper surface of chip 22 itself (¶0026).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to connect the through-silicon vias of the modified Bahadur heat pipe, which terminate at the outer face of the lower plate where the microelectronic device is attached, to the attached microelectronic device serving as the electrowetting controller, as taught by Bahadur '701, in order to supply the electrode actuation voltages from the chip being cooled and thereby integrate the heat spreader with the chip without a separate controller (Bahadur '701, ¶0019, ¶0026), the protruding copper vias of Oprins (¶0072) providing the bonding contact. In the resulting assembly the microelectronic device is in electrical contact with each electrically conductive via structure.
Regarding claim 19, Bahadur in view of Oprins teaches the assembly of claim 10 as set forth above, but does not expressly disclose that the plurality of electrodes are powered by the microelectronic device. Bahadur '701 discloses that the electrowetting heat spreader's electrodes are energized by a controller "which can be the chip being cooled" (¶0019), the controller selecting the electrodes to be energized based on the chip's predetermined hot-spot layout programmed into its memory or on thermal-sensor feedback (¶0019, ¶0021). It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to power the electrodes 203 of the modified Bahadur heat pipe from the attached microelectronic device, as taught by Bahadur '701, in order to drive the electrowetting actuation from the chip being cooled, which has direct knowledge of its own hot-spot locations and workload (Bahadur '701, ¶0019, ¶0021), through the through-silicon vias of the combination as set forth for claim 17.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure:
US 2023/0332839 – vapor chambers featuring wettability-patterned surfaces
US 2019/0285357 - middle component for heat dissipation device
Any inquiry concerning this communication or earlier communications from the examiner should be directed to ZHENGFU J FENG whose telephone number is (571) 272-2949. The examiner can normally be reached on Monday - Friday, 10AM - 6PM EST.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, JAYPRAKASH GANDHI can be reached at (571) 272-3740. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/ZHENGFU J FENG/
Primary Examiner, Art Unit 2835 September 5, 2026
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