Patent Abstract:
A chip package includes a thermal interface material disposed between a die backside and a heat sink. A dielectric sheet is also disposed between the die backside and the heat sink. The dielectric sheet diminishes overall heat transfer from the die to the heat sink by a small fraction of total possible heat transfer without the dielectric sheet. A method of operating the chip includes biasing the chip with the dielectric sheet in place.

Full Description:
TECHNICAL FIELD  
       [0001]     Embodiments relate generally to a chip package fabrication. More particularly, embodiments relate to heat-transfer and current-leakage issues in chip packages.  
       TECHNICAL BACKGROUND  
       [0002]     Issues that affect packaged integrated circuit (IC) devices include heat management, current leakage, and clock speed, among others. An IC die that cannot adequately reject heat will be adversely affected in clock speed. An IC die that has significant current leakage through the backside will also be adversely affected in clock speed.  
         [0003]     As die size and package size continue to be miniaturized, current leakage may exceed the current demand to operate the IC die. The mobile IC die segment of packaged IC devices is a particularly vulnerable area of technology as it is desired to improve battery life by decreasing electrical current demand. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0004]     In order to depict the manner in which the embodiments are obtained, a more particular description of embodiments briefly described above will be rendered by reference to exemplary embodiments that are illustrated in the appended drawings. Understanding that these drawings depict typical embodiments that are not necessarily drawn to scale and are not therefore to be considered to be limiting of its scope, the embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:  
         [0005]      FIG. 1  is a cross-section elevation of an apparatus that includes a dielectric sheet according to an embodiment;  
         [0006]      FIG. 2  is a cross-section elevation of an apparatus that includes a dielectric sheet according to an embodiment;  
         [0007]      FIG. 3  is a cross-section elevation of an apparatus that includes a dielectric sheet in an integrated heat spreader package according to an embodiment;  
         [0008]      FIG. 4  is a cross-section elevation of an apparatus that includes a dielectric sheet in an integrated heat spreader and heat slug package according to an embodiment;  
         [0009]      FIG. 5  is a cross-section elevation of an apparatus during the reworking of a flexible dielectric sheet according to an embodiment;  
         [0010]      FIG. 6  is a cross-section elevation of an apparatus during the reworking of a rigid dielectric sheet according to an embodiment;  
         [0011]      FIG. 7  is a flow chart that describes process flow embodiments; and  
         [0012]      FIG. 8  is a cut-away elevation that depicts a computing system according to an embodiment. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Embodiments in this disclosure relate to an apparatus that includes a dielectric sheet for heat transfer between the IC die and the heat spreader. Embodiments relate to both inorganic and organic dielectric sheets, as well as reworkable flexible and rigid dielectric sheets. Embodiments also relate to processes of assembling dielectric sheets into chip packages. Embodiments also relate to systems that incorporate dielectric sheets.  
         [0014]     The following description includes terms, such as upper, lower, first, second, etc. that are used for descriptive purposes only and are not to be construed as limiting. The embodiments of an apparatus or article described herein can be manufactured, used, or shipped in a number of positions and orientations. The terms “die” and “chip” generally refer to the physical object that is the basic workpiece that is transformed by various process operations into the desired integrated circuit device. A die is usually singulated from a wafer, and wafers may be made of semiconducting, non-semiconducting, or combinations of semiconducting and non-semiconducting materials. A board is typically a resin-impregnated fiberglass structure that acts as a mounting substrate for the die.  
         [0015]     Reference will now be made to the drawings wherein like structures may be provided with like suffix reference designations. In order to show the structures of various embodiments most clearly, the drawings included herein are diagrammatic representations of integrated circuit structures. Thus, the actual appearance of the fabricated structures, for example in a photomicrograph, may appear different while still incorporating the essential structures of the illustrated embodiments. Moreover, the drawings show the structures necessary to understand the illustrated embodiments. Additional structures known in the art have not been included to maintain the clarity of the drawings.  
         [0016]      FIG. 1  is a cross-section elevation of an apparatus  100  that includes a dielectric sheet according to an embodiment. The apparatus  100  includes a die  110  with an active surface  112  and a backside surface  114 . The die  110  can be electrically bumped by a plurality of solder bumps, one of which is designated with the reference numeral  116 . The die  110  is disposed upon a mounting substrate  118  that can be a board such as a printed wiring board, an interposer, a mezzanine board, an expansion card, a motherboard, or other mounting substrates. Electrical communication between the die  110  and the outside world can be achieved by a plurality of mounting substrate bumps, one of which is designated with the reference numeral  120  according to an embodiment.  
         [0017]     The thermal solution for conductively cooling the die  110  includes extracting heat through the backside surface  114  of the die  110 . In an embodiment, the die  110  is thermally coupled to a dielectric sheet  122 . The dielectric sheet  122  is in turn coupled to a thermal interface material (TIM)  124  that is a significant conductor of heat. In an embodiment, the TIM  124  is a metal with a high thermal conductivity in a range that is typical of metals such as copper, aluminum, silver, tin, tin-silver, tin-indium-silver, and the like. In an embodiment, the TIM  124  is a polymer-metal hybrid, which is often referred to as a polymer-solder hybrid (PSH). In an embodiment, the TIM  124  is a metal-metal hybrid, which includes a plurality of first metal particles of a first heat conductivity which are disposed in a matrix of a second metal of a second heat conductivity. In an embodiment, the first heat conductivity is higher than the second heat conductivity. In an embodiment, the second heat conductivity is higher than the first heat conductivity.  
         [0018]     In an embodiment, the die  110  includes a backside metallurgy  126  (BSM) that can be applied during the wafer phase of processing. In an embodiment, the dielectric sheet  122  can also be applied during the wafer phase of processing, followed by dicing to achieve the die  110 . The BSM  126  can assist the dielectric sheet  122  in adhering to the die  110 . For example in  FIG. 1 , the die  110  and the dielectric sheet  122  are depicted as including the interposed BSM  126  bonded to the die  110  and to the dielectric sheet  122  as a unit. In an embodiment, the BSM  126  is a titanium compound such as sputtered titanium metal. In an embodiment, the BSM  126  includes a titanium first layer disposed against the bare die  110  at the backside surface  114 , and a multiphasic, lead-free solder second layer disposed on the first layer. In an embodiment, the lead-free solder second layer is a material with a bulk solder phase such as AgSn, CuSn, AgCu, AgCuSn, and the like.  
         [0019]     In addition to the lead-free solder bulk phase, the lead-free solder second layer of the BSM  126  includes an intermetallic second phase that liquefies and dissolves into the first phase during die-attach processing. The intermetallic second phase of the BSM  126  includes an InBiZn as an additive to the first phase. The intermetallic second phase of the BSM  126  causes enhanced wetting upon the titanium first layer at a temperature range from about 95° C. to about 110° C. In this embodiment, the lead-free solder second layer of the BSM  126  is an AgSn solder first phase that includes about 80% to about 95% of the solder, and the intermetallic-forming second phase of the BSM  126  is a zinc-gold-indium intermetallic compound that includes the balance of the solder by weight, about 5% to about 20%. In this embodiment, the zinc-gold-indium intermetallic compound is present with about three parts zinc, five parts Au, and about one part indium.  
         [0020]     The die  110 , the BSM  126 , the dielectric sheet  122 , and the TIM  124  are thermally coupled to a heat sink  128 . Accordingly, any potentially electrically conductive path between the die  110  and the heat sink  128  is obstructed by the dielectric sheet  122 . By the combination of the TIM  124  and the dielectric sheet  122 , where the TIM  124  can perform with a heat-transfer capability of unity, i.e., in dimensionless units, but otherwise in units such as Watts/m 2 , the dielectric sheet  122  decreases the heat-transfer capability of the TIM  124  by not more than about 10% of unity according to an embodiment. In an embodiment, the dielectric sheet  122  decreases the heat-transfer capability of the TIM  124  by not more than about 5% of unity. In an embodiment, the dielectric sheet  122  decreases the heat-transfer capability of the TIM  124  by not more than about  1 % of unity. In an embodiment, the dielectric sheet  122  decreases the heat-transfer capability of the TIM  124  by not more than about 0.5% of unity. In an embodiment, the dielectric sheet  122  has a thickness of about 50 micrometers (μm). In an embodiment, the dielectric sheet  122  has a thickness of about 20 μm. In an embodiment, the dielectric sheet  122  has a thickness of about 10 μm. In an embodiment, the dielectric sheet  122  has a thickness of about 5 μm. In an embodiment, the dielectric sheet  122  has a thickness that is about 10 percent the thickness of the TIM  124 . In an embodiment, the dielectric sheet  122  has a thickness that is about five percent the thickness of the TIM  124 . In an embodiment, the dielectric sheet  122  has a thickness that is about one percent the thickness of the TIM  124 . In an embodiment, the dielectric sheet  122  has a thickness that is about 0.5 percent the thickness of the TIM  124 .  
         [0021]     Dielectric Sheet Materials  
         [0022]     In an embodiment, the dielectric sheet  122  is an inorganic. In an embodiment, the dielectric sheet  122  is an oxide such as BeO, TiO 2 , Al 2 O 3 , and SiO 2 . Other oxide embodiments can be used such as thoria, ceria, and the like. Another oxide embodiment includes spin-on glass (SOG), including silica, borosilicate glass (BSG), phosphosilicate glass (PSB), borophosphosilicate glass (BPSG) and the like. A specific oxide may be chosen for qualities such as dielectric constant, thermal conductivity, adhesion tendency to the die  110 , and others. In an embodiment, the dielectric sheet  122  is a nitride such as BN, AlN, and TiN. Other nitride embodiments can be used such as silicon nitride, e.g., amorphous Si x N y H z , AlBN or the like. In an embodiment, the dielectric sheet  122  is a thin diamond film that can be manufactured by chemical vapor deposition (CVD) during the wafer stage of processing. In an embodiment, the thin diamond film  122  is doped to alter the thermal conductivity and resistivity properties. For the above embodiments, the dielectric sheet  122  can be manufactured by CVD or spin-on processing according to known technique. And these dielectrics constitute selected but non-limiting rigid dielectric sheet embodiments.  
         [0023]     In an embodiment, the dielectric sheet  122  is an oxynitride such as boron oxynitride, aluminum oxynitride, silicon oxynitride, and titanium oxynitride. Other oxynitrides can be used according to a specific application.  
         [0024]     Various inorganics can be provided as the dielectric sheet  122  by CVD or otherwise. The table enumerates selected inorganics and selected properties.  
                                                                                     Kc 100° C.,   Kc 1400° C.,   Resistivity,           Compound   cal/cm-sec-K   cal/cm-sec-K   293 K, Ω-cm                                        Y 2 O 3     0.034   0.007   10 8              ZrO 2     0.005   0.006   10 1 -10 8             Al 2 O 3     0.072   0.013   10 16             BN   ˜0.075   ˜0.05   10 13             TiN   0.069   ˜0.018   22 × 10 4             SiN   ˜0.06   —   —           PVD diamond   ˜3.6   —   10 16                        
 
         [0025]     In an embodiment, the dielectric sheet  122  is an organic film such as a high-k dielectric, e.g., a non-conductive polymer with a dielectric constant greater than or equal to about 4. Such non-conductive polymers are conventional before applying them to an IC package embodiment as set forth in this disclosure. And these organic dielectrics constitute selected but non-limiting flexible dielectric sheet embodiments.  
         [0026]     In an embodiment, the dielectric sheet  122  includes a combination of at least two of any disclosed oxide, nitride, SOG oxide, oxynitride, thin diamond film, and organic.  
         [0027]      FIG. 2  is a cross-section elevation of an apparatus  200  that includes a dielectric sheet according to an embodiment. The apparatus  200  includes a die  210  with an active surface  212  and a backside surface  214 . The die  210  can be electrically bumped by a plurality of solder bumps, one of which is designated with the reference numeral  216 . The die  210  is disposed upon a mounting substrate  218  that can be a board such as a printed wiring board, an interposer, a mezzanine board, an expansion card, a motherboard, or other mounting substrates. Electrical communication between the die  210  and the outside world can be achieved by a plurality of mounting substrate bumps, one of which is designated with the reference numeral  220  according to a embodiment.  
         [0028]     The thermal solution for conductively cooling the die  210  includes extracting heat through the backside surface  214  of the die  210 . In an embodiment, the die  210  is thermally coupled to a TIM  224  that is a significant conductor of heat. The TIM  224  is in turn coupled to a dielectric sheet  222 . In an embodiment, the TIM  224  is a metal with a high thermal conductivity in a range that is typical of metals such as copper, aluminum, silver, tin, tin-silver, tin-indium-silver, and the like. In an embodiment, the TIM  224  is a polymer-metal hybrid, such as PSH. In an embodiment, the TIM  224  is a metal-metal hybrid, which includes a plurality of first metal particles of a first heat conductivity which are disposed in a matrix of a second metal of a second heat conductivity. In an embodiment, the first heat conductivity is higher than the second heat conductivity. In an embodiment, the second heat conductivity is higher than the first heat conductivity.  
         [0029]     In an embodiment, the die  210  includes a BSM  226  that can be applied during the wafer phase of processing. The BSM  226  can assist the TIM  224  in adhering to the die  210 . For example in  FIG. 2 , the die  210  and the TIM  224  are depicted as including the BSM  226  bonded to the die  210  and to the TIM  224  as a unit. Any embodiment of a BSM set forth in this disclosure can be used between the die  210  and the TIM  224 .  
         [0030]     The die  210 , the BSM  226 , and the TIM  224  are thermally coupled to a heat sink  228  through a dielectric sheet  222 . Accordingly, any potentially electrically conductive path between the die  210  and the heat sink  228  is obstructed by the dielectric sheet  222 . By the combination of the TIM  224  and the dielectric sheet  222 , where the TIM  224  can perform with a heat-transfer capability of unity, i.e., in dimensionless units, but otherwise in units such as Watts/m 2 , the dielectric sheet  222  decreases the heat-transfer capability of the TIM  224  by not more than about 10% of unity according to an embodiment. In an embodiment, the dielectric sheet  222  decreases the heat-transfer capability of the TIM  224  by not more than about 5% of unity. In an embodiment, the dielectric sheet  222  decreases the heat-transfer capability of the TIM  224  by not more than about 1% of unity. In an embodiment, the dielectric sheet  222  decreases the heat-transfer capability of the TIM  224  by not more than about 0.5% of unity. In an embodiment, the dielectric sheet  222  has a thickness of about 50 micrometers (μm). In an embodiment, the dielectric sheet  222  has a thickness of about 20 μm. In an embodiment, the dielectric sheet  222  has a thickness of about 10 μm. In an embodiment, the dielectric sheet  222  has a thickness of about 5 μm. In an embodiment, the dielectric sheet  222  has a thickness that is about 10 percent the thickness of the TIM  224 . In an embodiment, the dielectric sheet  222  has a thickness that is about five percent the thickness of the TIM  224 . In an embodiment, the dielectric sheet  222  has a thickness that is about one percent the thickness of the TIM  224 . In an embodiment, the dielectric sheet  222  has a thickness that is about 0.5 percent the thickness of the TIM  224 .  
         [0031]     In an embodiment, the dielectric sheet  222  includes a combination of at least two of any disclosed oxide, nitride, SOG oxide, oxynitride, thin diamond film, and organic.  
         [0032]      FIG. 3  is a cross-section elevation of an apparatus  300  that includes a dielectric sheet in an integrated heat spreader package according to an embodiment. The apparatus  300  includes a die  310  with an active surface  312  and a backside surface  314 . The die  310  can be electrically bumped by a plurality of solder bumps, one of which is designated with the reference numeral  316 . The die  310  is disposed upon a mounting substrate  318  that can be a board such as a printed wiring board, an interposer, a mezzanine board, an expansion card, a motherboard, or other mounting substrates. Electrical communication between the die  310  and the outside world can be achieved by a plurality of mounting substrate bumps, one of which is designated with the reference numeral  320  according to a embodiment.  
         [0033]     The thermal solution for conductively cooling the die  310  includes extracting heat through the backside surface  314  of the die  310 . In an embodiment, the die  310  is thermally coupled to a TIM  324  that is a significant conductor of heat. The TIM  324  is in turn coupled to a dielectric sheet  322 . In an embodiment, the TIM  324  is a metal with a high thermal conductivity in a range that is typical of metals such as copper, aluminum, silver, tin, tin-silver, tin-indium-silver, and the like. In an embodiment, the TIM  324  is a polymer-metal hybrid, such as PSH. In an embodiment, the TIM  324  is a metal-metal hybrid, which includes a plurality of first metal particles of a first heat conductivity which are disposed in a matrix of a second metal of a second heat conductivity. In an embodiment, the first heat conductivity is higher than the second heat conductivity. In an embodiment, the second heat conductivity is higher than the first heat conductivity.  
         [0034]     In an embodiment, the die  310  includes a BSM  326  that can be applied during the wafer phase of processing. The BSM  326  can assist the TIM  324  in adhering to the die  310 . For example in  FIG. 3 , the die  310  and the TIM  324  are depicted as including the BSM  326  bonded to the die  310  and to the TIM  324  as a unit. Any embodiment of a BSM set forth in this disclosure can be used between the die  310  and the TIM  324 .  
         [0035]     The die  310 , the BSM  326 , and the TIM  324  are thermally coupled to an integrated heat spreader (IHS)  328  through a dielectric sheet  322 . Accordingly, any potentially electrically conductive path between the die  310  and the IHS  328  is obstructed by the dielectric sheet  322 . By the combination of the TIM  224  and the dielectric sheet  322 , where the TIM  324  can perform with a heat-transfer capability of unity, i.e., in dimensionless units, but otherwise in units such as Watts/m 2 , the dielectric sheet  322  decreases the heat-transfer capability of the TIM  324  by not more than about 10% of unity according to an embodiment. In an embodiment, the dielectric sheet  322  decreases the heat-transfer capability of the TIM  324  by not more than about 5% of unity. In an embodiment, the dielectric sheet  322  decreases the heat-transfer capability of the TIM  324  by not more than about 1% of unity. In an embodiment, the dielectric sheet  322  decreases the heat-transfer capability of the TIM  324  by not more than about 0.5% of unity. In an embodiment, the dielectric sheet  322  has a thickness of about 50 micrometers (μm). In an embodiment, the dielectric sheet  322  has a thickness of about 20 μm. In an embodiment, the dielectric sheet  322  has a thickness of about 10 μm. In an embodiment, the dielectric sheet  322  has a thickness of about 5 μm. In an embodiment, the dielectric sheet  322  has a thickness that is about 10 percent the thickness of the TIM  324 . In an embodiment, the dielectric sheet  322  has a thickness that is about five percent the thickness of the TIM  324 . In an embodiment, the dielectric sheet  322  has a thickness that is about one percent the thickness of the TIM  324 . In an embodiment, the dielectric sheet  322  has a thickness that is about 0.5 percent the thickness of the TIM  324 .  
         [0036]     In an embodiment, the dielectric sheet  322  includes a combination of at least two of any disclosed oxide, nitride, SOG oxide, oxynitride, thin diamond film, and organic.  
         [0037]      FIG. 4  is a cross-section elevation of an apparatus  400  that includes a dielectric sheet in an integrated heat spreader and heat slug package according to an embodiment. The apparatus  400  includes a die  410  with an active surface  412  and a backside surface  414 . The die  410  can be electrically bumped by a plurality of solder bumps, one of which is designated with the reference numeral  416 . The die  410  is disposed upon a mounting substrate  418  that can be a board such as a printed wiring board, an interposer, a mezzanine board, an expansion card, a motherboard, or other mounting substrates. Electrical communication between the die  410  and the outside world can be achieved by a plurality of mounting substrate bumps, one of which is designated with the reference numeral  420  according to a embodiment.  
         [0038]     The thermal solution for conductively cooling the die  410  includes extracting heat through the backside surface  414  of the die  410 . In an embodiment, the die  410  is thermally coupled to a TIM  424  that is a significant conductor of heat. The TIM  424  is in turn coupled to an IHS  428 . The IHS  428  is in turn coupled to a dielectric sheet  422  that is in turn coupled to a heat slug  430 . In an embodiment, the TIM  424  is a metal with a high thermal conductivity in a range that is typical of metals such as copper, aluminum, silver, tin, tin-silver, tin-indium-silver, and the like. In an embodiment, the TIM  424  is a polymer-metal hybrid, such as PSH. In an embodiment, the TIM  424  is a metal-metal hybrid, which includes a plurality of first metal particles of a first heat conductivity which are disposed in a matrix of a second metal of a second heat conductivity. In an embodiment, the first heat conductivity is higher than the second heat conductivity. In an embodiment, the second heat conductivity is higher than the first heat conductivity.  
         [0039]     In an embodiment, the heat slug  430  is a heat-transfer article such as a heat pipe. In an embodiment, the heat slug  430  is a heat-transfer article such as an air-cooled heat sink. In an embodiment, the heat slug  430  is a heat-transfer article such as a convection air-cooled heat sink.  
         [0040]     In an embodiment, the die  410  includes a BSM  426  that can be applied during the wafer phase of processing. The BSM  426  can assist the TIM  424  in adhering to the die  410 . For example in  FIG. 4 , the die  410  and the TIM  424  are depicted as including the BSM  426  bonded to the die  410  and to the TIM  424  as a unit. Any embodiment of a BSM set forth in this disclosure can be used between the die  410  and the TIM  424 .  
         [0041]     The die  410 , the BSM  426 , the TIM  424  and the IHS  428  are thermally coupled to the heat slug  430  through a dielectric sheet  422 . Accordingly, any potentially electrically conductive path between the die  410  and the heat slug  430  is obstructed by the dielectric sheet  422 . By the combination of the TIM  424  and the dielectric sheet  422 , where the TIM  424  can perform with a heat-transfer capability to the heat slug  430  of unity, i.e., in dimensionless units, but otherwise in units such as Watts/m 2 , the dielectric sheet  422  decreases the heat-transfer capability of the TIM  424  by not more than about 10% of unity. In an embodiment, the dielectric sheet  422  decreases the heat-transfer capability of the TIM  424  by not more than about 5% of unity. In an embodiment, the dielectric sheet  422  decreases the heat-transfer capability of the TIM  424  by not more than about 1% of unity. In an embodiment, the dielectric sheet  422  decreases the heat-transfer capability of the TIM  424  by not more than about 0.5% of unity. In an embodiment, the dielectric sheet  422  has a thickness of about 50 micrometers (μm). In an embodiment, the dielectric sheet  422  has a thickness of about 20 μm. In an embodiment, the dielectric sheet  422  has a thickness of about 10 μm. In an embodiment, the dielectric sheet  422  has a thickness of about 5 μm. In an embodiment, the dielectric sheet  422  has a thickness that is about 10 percent the thickness of the TIM  424 . In an embodiment, the dielectric sheet  422  has a thickness that is about five percent the thickness of the TIM  424 . In an embodiment, the dielectric sheet  422  has a thickness that is about one percent the thickness of the TIM  424 . In an embodiment, the dielectric sheet  422  has a thickness that is about 0.5 percent the thickness of the TIM  424 .  
         [0042]     In an embodiment, the dielectric sheet  422  includes a combination of at least two of any disclosed oxide, a nitride, an SOG oxide, oxynitride, thin diamond film, and organic.  
         [0043]      FIG. 5  is a cross-section elevation of an apparatus  500  during the reworking of a flexible dielectric sheet according to an embodiment. The apparatus  500  includes a die  510  with an active surface  512  and a backside surface  514 . The die  510  can be electrically bumped by a plurality of solder bumps, one of which is designated with the reference numeral  516 . The die  510  is disposed upon a mounting substrate  518  that can be a board such as a printed wiring board, an interposer, a mezzanine board, an expansion card, a motherboard, or other mounting substrates. Electrical communication between the die  510  and the outside world can be achieved by a plurality of mounting substrate bumps, one of which is designated with the reference numeral  520  according to a embodiment.  
         [0044]     In an embodiment, reworking of the thermal solution for the die  510  includes removing a dielectric sheet  522  and installing a replacement dielectric sheet. As depicted in  FIG. 5 , the dielectric sheet  522  is disposed directly upon a BSM  526  of the die  510 . Where the dielectric sheet  522  is flexible, it can be peeled off the BSM  526  if present, or it can be peeled off the backside surface  514  of the die  510  if the BSM  526  is not present. The dielectric sheet  522  is being peeled off in the direction of the directional arrow  532 .  
         [0045]     Reworking the thermal solution according to these embodiments can be achieved during initial processing before shipping, if a different dielectric sheet is desired to replace the dielectric sheet  522 . Similarly, reworking the thermal solution according to these embodiments can be achieved after shipping, i.e., if the apparatus  500  requires a different thermal solution than that with which it was shipped.  
         [0046]      FIG. 6  is a cross-section elevation of an apparatus  600  during the reworking of a rigid dielectric sheet according to an embodiment. The apparatus  600  includes a die  610  with an active surface  612  and a backside surface  614 . The die  610  can be electrically bumped by a plurality of solder bumps, one of which is designated with the reference numeral  616 . The die  610  is disposed upon a mounting substrate  618  that can be a board such as a printed wiring board, an interposer, a mezzanine board, an expansion card, a motherboard, or other mounting substrates. Electrical communication between the die  610  and the outside world can be achieved by a plurality of mounting substrate bumps, one of which is designated with the reference numeral  620  according to a embodiment.  
         [0047]     In an embodiment, reworking of the thermal solution for the die  610  includes removing a dielectric sheet  622  and installing a replacement dielectric sheet. As depicted in  FIG. 6 , the dielectric sheet  622  is disposed directly upon a BSM  626  of the die  610 . Where the dielectric sheet  622  is rigid such as an oxide, a nitride, a thin diamond film, or others, it can be removed from the BSM  626  by grinding if present, or it can be ground off the backside surface  614  of the die  610  if the BSM  626  is not present. The dielectric sheet  622  is being ground off in the direction of the directional arrow  634 , with a grinding wheel  636  according to an embodiment.  
         [0048]     Reworking the thermal solution according to these embodiments can be achieved during initial processing if a different dielectric sheet is desired to replace the dielectric sheet  622 . Similarly, reworking the thermal solution according to these embodiments can be achieved after shipping, i.e., if the apparatus  600  requires a different thermal solution than that with it was shipped.  
         [0049]     In an embodiment, a method of operating an IC device includes applying a bias to a die. Reference is made to  FIG. 1 . In an embodiment, a bias is applied across a circuit through the solder bumps  116 , such that a bias is imposed upon the die  110 . In an embodiment, a bias that is a fraction of the voltage requirement of the die  110  is applied across a circuit in the solder bumps  116 , such that a bias is imposed upon the die  110 . Accordingly, current leakage diminishes. In an embodiment, a bias in a range from about five percent to about 50 percent of the voltage requirement of the die  110  is applied across a circuit in the die  110  through the solder bumps  116 , such that a bias is imposed upon the die  110 . Accordingly, current leakage diminishes. In an embodiment, the voltage that is applied is a range from about 1 Volt to about 6 Volts. In an embodiment, a bias of about five percent of the voltage requirement of the die  110 , about 3.5 Volts, is applied across a circuit in the die  110  through the solder bumps  116 , such that a bias is imposed upon the entire integrated circuitry of the die  110 . Accordingly, current leakage diminishes.  
         [0050]     In an embodiment, the IC device that includes a dielectric sheet embodiment is a mobile device such as the apparatus  100  depicted in  FIG. 1 . In an embodiment, the IC device is a desktop device such as the apparatus  300  depicted in  FIG. 3 . In an embodiment, the IC device is a desktop device such as the apparatus  400  depicted in  FIG. 4 . In  FIG. 4 , although some current leakage may occur through the IHS  428 , because of the dielectric sheet  422 , significant current leakage is prevented to the larger heat sink that is the heat slug  430 .  
         [0051]      FIG. 7  is a flow chart that describes process flow embodiments  700 .  
         [0052]     At  710  the process includes forming a BSM upon a wafer before singulating the wafer into dice. In an embodiment, the BSM is any BSM example set forth in this disclosure. At  712  the process includes forming a dielectric sheet on the BSM of the wafer. In an embodiment at  712  the process includes forming a dielectric sheet on the backside surface of the wafer if no BSM is present.  
         [0053]     At  720 , the process includes dicing the wafer. In an embodiment, the process includes  712  and concludes at  720 .  
         [0054]     At  730 , the process includes forming a dielectric sheet between a die and a heat sink to obstruct any potentially electrically conductive path therebetween. In an embodiment, the process includes  710 ,  720 , and concludes at  730 .  
         [0055]     At  740 , the process includes coupling the die to the heat sink, with the dielectric sheet therebetween, to form an IC chip package. In an embodiment, the process includes reflow heating of the BSM during coupling of the die to the heat sink as set forth in this disclosure. In an embodiment, the process commences and terminates at  740 . In an embodiment, the process commences at  730  and terminates at  740 .  
         [0056]     At  750 , the process includes removing the dielectric sheet and installing a replacement dielectric sheet.  
         [0057]     At  760 , the process includes installing the IC chip package to a structure to form a computing system. According to an embodiment illustrated in  FIG. 8 , the structure can be a computer shell or a board  820 . In an embodiment, the process commences at  760  and terminates at  770 .  
         [0058]      FIG. 8  is a cut-away elevation that depicts a computing system  800  according to an embodiment. One or more of the foregoing embodiments of the dielectric sheet embodiments may be utilized in a computing system, such as a computing system  800  of  FIG. 8 . Hereinafter any dielectric sheet embodiment alone or in combination with any other embodiment is referred to as an embodiment(s) configuration.  
         [0059]     The computing system  800  includes at least one processor (not pictured), which is enclosed in an IC chip package  810 , a data storage system  812 , at least one input device such as a keyboard  814 , and at least one output device such as a monitor  816 , for example. The computing system  800  includes a processor that processes data signals, and may include, for example, a microprocessor, available from Intel Corporation. In addition to the keyboard  814 , the computing system  800  can include another user input device such as a mouse  818 , for example. The computing system  800  can include a structure, after processing as depicted in FIG.  3 , including the die  310 , the dielectric sheet  322 , and the integrated heat spreader  328 .  
         [0060]     For purposes of this disclosure, a computing system  800  embodying components in accordance with the claimed subject matter may include any system that utilizes a microelectronic device system, which may include, for example, at least one of the dielectric sheet embodiments that is coupled to data storage such as dynamic random access memory (DRAM), polymer memory, flash memory, and phase-change memory. In this embodiment, the embodiment(s) is coupled to any combination of these functionalities by being coupled to a processor. In an embodiment, however, an embodiment(s) configuration set forth in this disclosure is coupled to any of these functionalities. For an example embodiment, data storage includes an embedded DRAM cache on a die. Additionally in an embodiment, the embodiment(s) configuration that is coupled to the processor (not pictured) is part of the system with an embodiment(s) configuration that is coupled to the data storage of the DRAM cache. Additionally in an embodiment, an embodiment(s) configuration is coupled to the data storage  812 .  
         [0061]     In an embodiment, the computing system  800  can also include a die that contains a digital signal processor (DSP), a micro controller, an application specific integrated circuit (ASIC), or a microprocessor. In this embodiment, the embodiment(s) configuration is coupled to any combination of these functionalities by being coupled to a processor. For an example embodiment, a DSP is part of a chipset that may include a stand-alone processor and the DSP as separate parts of the chipset on the board  820 . In this embodiment, an embodiment(s) configuration is coupled to the DSP, and a separate embodiment(s) configuration may be present that is coupled to the processor in the IC chip package  810 . Additionally in an embodiment, an embodiment(s) configuration is coupled to a DSP that is mounted on the same board  820  as the IC chip package  810 . It can now be appreciated that the embodiment(s) configuration can be combined as set forth with respect to the computing system  800 , in combination with an embodiment(s) configuration as set forth by the various embodiments of the dielectric sheet within this disclosure and their equivalents.  
         [0062]     It can now be appreciated that embodiments set forth in this disclosure can be applied to devices and apparatuses other than a traditional computer. For example, a die can be packaged with an embodiment(s) configuration, and placed in a portable device such as a wireless communicator or a hand-held device such as a personal data assistant and the like. Another example is a die that can be packaged with an embodiment(s) configuration and placed in a vehicle such as an automobile, a locomotive, a watercraft, an aircraft, or a spacecraft.  
         [0063]     The Abstract is provided to comply with 37 C.F.R. §1.72(b) requiring an abstract that will allow the reader to quickly ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.  
         [0064]     In the foregoing Detailed Description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate preferred embodiment.  
         [0065]     It will be readily understood to those skilled in the art that various other changes in the details, material, and arrangements of the parts and method stages which have been described and illustrated in order to explain the nature of this invention may be made without departing from the principles and scope of the invention as expressed in the subjoined claims.

Technology Classification (CPC): 7