Abstract:
A semiconductor package includes a semiconductor chip including a semiconductor substrate and a plurality of cell transistors arranged on the semiconductor substrate. Channel regions of the cell transistors have channel lengths that extend in a first direction, and the package further includes a supporting substrate having an upper surface on which the semiconductor chip is affixed. The supporting substrate is configured to bend in response to a temperature increase in a manner that applies a tensile stress to the channel regions of the semiconductor chip in the first direction. Related methods are also disclosed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC §119 to Korean Patent Application No. 10-2007-128353, filed on Dec. 11, 2007 in the Korean Intellectual Property Office (KIPO), the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present invention relates to semiconductor packages and methods of manufacturing the same. More particularly, the present invention relates to semiconductor packages including molded semiconductor chips that may be electrically connected to an external device, and methods of manufacturing semiconductor packages including molded semiconductor chips that may be electrically connected to an external device. 
     Generally, semiconductor memory devices may be classified as volatile memory devices or non-volatile memory devices. Volatile memory devices may have a relatively rapid data input/output rate, but may lose data over time. The non-volatile memory devices may have a relatively slow data input/output rate, but may continuously store data for significant periods of time, even when no power is applied to the device. 
     Non-volatile memory devices may be classified as NAND type flash memory devices or NOR type flash memory devices depending on their cell layout. The NAND type flash memory devices may include unit strings where cell transistors may be serially connected to each other. The unit strings may be serially connected between a bit line and a ground line. In contrast, the NOR type flash memory devices may include cell transistors connected in parallel with each other between a bit line and a ground line. 
     The NAND type flash memory device may include a plurality of gate structures in a cell transistor, ground selection lines, string selection lines and common source lines arranged at peripheries of the gate structures. The gate structure may include a gate electrode and a channel region under the gate electrode. 
     A voltage may be applied to the common source lines in the periphery of the cell transistor to move carriers through the channel region. When the voltage is applied to the channel region in the gate structures of the cell transistors, the carriers may be moved through the channel region to store or erase data. 
     However, when the temperature at which the memory device is operated is increased, the mobility of lattices in the channel region may be increased. Because the lattices may interrupt the movements of the carriers, the mobility of the carriers may be decreased. As a result, an operational current of the memory device may be reduced. 
     SUMMARY 
     Some embodiments provide semiconductor packages and/or packaging methods that may be capable of compensating a low mobility of carriers caused by an increase of the temperature of a semiconductor chip within the package. 
     A semiconductor package according to some embodiments includes a semiconductor chip including a semiconductor substrate and a plurality of cell transistors arranged on the semiconductor substrate. Channel regions of the cell transistors have channel lengths that extend in a first direction, and the package further includes a supporting substrate having an upper surface on which the semiconductor chip is affixed. The supporting substrate may be configured to bend in response to a temperature increase in a manner that applies a tensile stress to the channel regions of the semiconductor chip in the first direction. 
     The supporting substrate may be configured to bend in a direction toward the semiconductor chip in response to the temperature increase. In some embodiments, the supporting substrate may be configured to bend in a second direction substantially perpendicular to the first direction in response to the temperature increase. The supporting substrate may be configured to bend in response to the temperature increase without any externally applied force. 
     The supporting substrate may include a bimetal including a first metal plate and a second metal plate on the first metal plate. The second metal plate may be between the first metal plate and the semiconductor chip, and the first and second metal plates each have a width that is greater than a width of the semiconductor substrate. The first metal plate may have a first coefficient of thermal expansion and the second metal plate may have a second coefficient of thermal expansion that may be higher than the first coefficient of thermal expansion. In some embodiments, the second coefficient of thermal expansion may be lower than the first coefficient of thermal expansion. 
     The semiconductor package may further include a supporting member configured to support a side surface of the supporting substrate when the supporting substrate bends. 
     The semiconductor package may further include a compressing member adjacent the supporting substrate. The compressing member may be configured to expand in response to the temperature increase, to thereby compress and bend the supporting substrate in response to the temperature increase. 
     The semiconductor package may further include a molding member around the semiconductor chip and the supporting substrate. The compressing member may include a member that contacts a central portion of the supporting substrate and that has a coefficient of thermal expansion that is higher than a coefficient of thermal expansion of the molding member. 
     In some embodiments, the compressing member may include a support member that contacts side surfaces of the supporting substrate in the first direction, and the compressing member may have a coefficient of thermal expansion that is higher than a coefficient of thermal expansion of the molding member. 
     Methods of manufacturing a semiconductor package according to some embodiments include providing a semiconductor chip that includes a semiconductor substrate and a plurality of cell transistors arranged on the semiconductor substrate. Channel regions of the cell transistors have channel lengths that extend in a first direction, and the methods further include affixing the semiconductor chip on an upper surface of a supporting substrate. The supporting substrate may be configured to bend in response to a temperature increase in a manner that applies tensile stress to the channel regions of the semiconductor chip in the first direction. 
     The supporting substrate may bend in a direction toward the semiconductor chip in response to the temperature increase. In some embodiments, the supporting substrate may bend in a second direction substantially perpendicular to the first direction in response to the temperature increase. The supporting substrate may be configured to bend in response to the temperature increase without any externally applied force. 
     The supporting substrate may include a bimetal including a first metal plate and a second metal plate on the first metal plate. The second metal plate may be between the first metal plate and the semiconductor chip, and the first and second metal plates each have a width that is greater than a width of the semiconductor substrate. 
     The first metal plate may have a first coefficient of thermal expansion and the second metal plate may have a second coefficient of thermal expansion that is higher than the first coefficient of thermal expansion. In some embodiments, the second coefficient of thermal expansion may be lower than the first coefficient of thermal expansion. 
     The methods may further include forming a supporting member configured to support a side surface of the supporting substrate. 
     The methods may further include forming a compressing member adjacent the supporting substrate. The compressing member may be configured to expand in response to the temperature increase to thereby compress and bend the supporting substrate in response to the temperature increase. 
     The methods may further include forming a molding member around the semiconductor chip and the supporting substrate, and the compressing member may include a member that contacts a central portion of the supporting substrate and that has a coefficient of thermal expansion that is higher than a coefficient of thermal expansion of the molding member. In some embodiments, the compressing member may include a support member that contacts side surfaces of the supporting substrate in the first direction, and the compressing member may have a coefficient of thermal expansion that may be higher than a coefficient of thermal expansion of the molding member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate certain embodiment(s) of the invention. In the drawings: 
         FIG. 1  is a cross-sectional view illustrating a semiconductor package in accordance with some embodiments; 
         FIG. 2  is a cross-sectional view illustrating a semiconductor chip in the semiconductor package of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view illustrating the semiconductor package of  FIG. 1  when a temperature is increased; 
         FIG. 4  is a cross-sectional view illustrating a semiconductor package in accordance with some embodiments; 
         FIG. 5  is a cross-sectional view illustrating the semiconductor package of  FIG. 4  when a temperature is increased; 
         FIG. 6  is a cross-sectional view illustrating a semiconductor package in accordance with some embodiments; 
         FIG. 7  is a cross-sectional view illustrating a semiconductor chip in the semiconductor package of  FIG. 6 ; 
         FIG. 8  is a cross-sectional view illustrating the semiconductor package of  FIG. 6  when a temperature is increased; 
         FIG. 9  is a cross-sectional view illustrating a semiconductor package of accordance with some embodiments; 
         FIG. 10  is a cross-sectional view illustrating the semiconductor package of  FIG. 9  when a temperature is increased; 
         FIGS. 11A ,  11 B and  11 C are cross-sectional views illustrating methods of manufacturing the semiconductor package of  FIG. 1  according to some embodiments; and 
         FIGS. 12A ,  12 B and  12 C are cross-sectional views illustrating methods of manufacturing the semiconductor package of  FIG. 4  according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Various embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some example embodiments are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. 
     It will be understood that when an element or layer is referred to as being “on,” “connected to” or “coupled to” another element or layer, it can be directly on, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Like numerals refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that, although the terms first, second, third etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
     The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized examples (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present invention. 
     Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     Hereinafter, exemplary embodiments will be explained in detail with reference to the accompanying drawings. 
       FIG. 1  is a cross-sectional view illustrating a semiconductor package in accordance with some embodiments, and  FIG. 2  is a cross-sectional view illustrating a semiconductor chip in the semiconductor package in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a semiconductor package  100  may include a semiconductor chip  110 , a supporting substrate  120 , a supporting member  130  and a molding member  140 . 
     The semiconductor chip  110  may include a semiconductor substrate  112  and cell transistors  114  formed on the semiconductor substrate  112 . 
     In some embodiments, the semiconductor substrate  112  may include a silicon substrate, a silicon-germanium substrate, a silicon-on-insulator substrate, or any other suitable substrate. In some embodiments, the semiconductor substrate  112  may be a silicon substrate oriented in the &lt;100&gt; crystal direction. Alternatively, the semiconductor substrate  112  may have a &lt;110&gt; crystal direction. 
     The cell transistors  114  may be formed on an upper surface  112   a  of the semiconductor substrate  112 . The cell transistors  114  may have a string structure arranged in a first direction. For example, when the semiconductor substrate  112  has the &lt;100&gt; crystal direction, the cell transistors  114  may have a string structure arranged in the &lt;100&gt; direction. Alternatively, when the semiconductor substrate  112  has the &lt;110&gt; crystal direction, the cell transistors  114  may have a string structure arranged in the &lt;110&gt; direction inclined to a &lt;100&gt; plane by about 45°. That is, the first direction may be substantially the same as the &lt;100&gt; direction. 
     The cell transistor  114  may include a tunnel oxide layer  114   a , a floating gate electrode  114   b , a dielectric layer  114   c , a control gate electrode  114   d , source/drain regions  114   e  and a channel region  114   f.    
     The tunnel oxide layer  114   a  may be formed on the semiconductor substrate  112 . In some embodiments, the tunnel oxide layer  114   a  may include silicon oxide. Alternatively, the tunnel oxide layer  114   a  may include a material having a dielectric constant higher than that of silicon oxide. 
     The floating gate electrode  114   b  may be formed on the tunnel oxide layer  114   a . In some embodiments, the floating gate electrode  114   b  may include polysilicon, amorphous silicon, etc. In some embodiments, the floating gate electrode  114   b  may include silicon nitride. Further, the floating gate electrode  114   b  may include a material having a dielectric constant higher than that of silicon nitride. For example, the floating gate electrode  114   b  may include metal oxide, metal oxynitride, metal silicon oxide, metal oxynitride, etc. In particular, the floating gate electrode  114   b  may include hafnium, zirconium, tantalum, etc. In some embodiments, the floating gate electrode  114   b  may include a silicon-rich oxide layer and/or a silicon nanocrystal layer. Further, the floating gate electrode  114   b  may have a laminate structure in which a silicon-rich oxide layer and a silicon nanocrystal layer are alternately stacked. 
     The dielectric layer  114   c  may be formed on the floating gate electrode  114   b . In some embodiments, the dielectric layer  114   c  may include a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer and/or a stacked structure thereof. In some embodiments, the dielectric layer  114   c  may include metal oxide, metal oxynitride, metal silicon oxide, metal silicon oxynitride, and the like having a high dielectric constant. 
     The control gate electrode  114   d  may be formed on the dielectric layer  114   c . In some embodiments, the control gate electrode  114   d  may include metal oxide, metal nitride, metal oxynitride, etc. For example, the control gate electrode  114   d  may include metal silicide. Examples of metal silicide may include tungsten silicide, tantalum silicide, cobalt silicide, titanium silicide, etc. 
     The source/drain regions  114   e  may be formed in a surface of the semiconductor substrate  112  adjacent to a gate structure that may include the tunnel oxide layer  114   a , the floating gate electrode  114   b , the dielectric layer  114   c  and the control gate electrode  114   d . In some embodiments, the source/drain regions  114   e  may be formed by doping the surface of the semiconductor substrate  112  adjacent to the gate structure with impurities. 
     The channel region  114   f  may be formed between the adjacent source/drain regions  114   e . The channel region  114   f  may have a lengthwise direction  115  that is substantially the same as an arrangement direction of the cell transistors  114 . As used herein, “channel length” of a MOS transistor refers to the distance beneath the gate from the source region to the drain region of the transistor. The lengthwise direction  115  thus refers to the direction from the source region to the drain region of the transistor in which the channel length is defined. When a voltage is applied to the semiconductor chip  110 , carriers may be moved in the lengthwise direction between the adjacent source/drain regions  114   e  to charge/discharge charges in/from the floating gate electrode  114   b . In some embodiments, when the semiconductor chip  110  corresponds to a NAND flash memory device, the cell transistor  114  may correspond to an NMOS transistor, in which the majority carriers are electrons. 
     The supporting substrate  120  may have an upper surface  120   a  on which the semiconductor chip  110  may be fixed. In some embodiments, the supporting substrate  120  may include a printed circuit board (PCB) having wirings. The wirings may transmit a voltage to the semiconductor substrate  110  and/or the cell transistors  114 . Alternatively, the supporting substrate  120  may include a die, block, wafter or the like that does not include wirings and is provided for mechanical support for the semiconductor chip  110 . 
     In some embodiments, the supporting substrate  120  may include a bimetal. The bimetal may include a first metal plate  120 - 1  having a first coefficient of thermal expansion, and a second metal plate  120 - 2  placed on the first metal plate  120 - 1  and having a second coefficient of thermal expansion higher than the first coefficient of thermal expansion, wherein the semiconductor chip  110  is mounted on the second metal plate  120 - 2  so that the second metal plate  120 - 2  is between the semiconductor chip  110  and the first metal plate  120 - 1 . The first metal plate  120 - 1  may include an alloy of nickel and iron. The second metal plate  120 - 2  may include an alloy of nickel, manganese and iron, an alloy of nickel, molybdenum and iron, an alloy of nickel, manganese and copper, etc. Because the second metal plate  120 - 2  has a higher coefficient of thermal expansion than the first metal plate  120 - 1 , a central portion  120   c  of the supporting substrate  120  may be bent upwardly (i.e. toward the semiconductor chip  110 ) in response to a temperature increase. 
     The supporting member  130  may be arranged in a direction  115  that is substantially the same as the first direction, i.e., the arrangement direction of the cell transistors  114  to fix both side surfaces  120   b  of the supporting substrate  120 . In some embodiments, the supporting member  130  may include a material having a low coefficient of thermal expansion that may not expand significantly in response to a temperature increase. Alternatively, the supporting member  130  may include a material having a high coefficient of thermal expansion that may expand in response to a temperature increase. Thus, the supporting member  130  may compress both side surfaces  120   b  of the supporting substrate  120 . As a result, because the supporting member  130  may support the both side surfaces  120   b  of the supporting substrate  120 , the bending of the supporting substrate  120  may be enhanced. 
     Alternatively, the supporting substrate  120  may be bent without use of the supporting member  130 . 
     The molding member  140  may surround the semiconductor chip  110 , the supporting substrate  120  and the supporting member  130 . The molding member  140  may protect the semiconductor chip  110 , the supporting substrate  120  and the supporting member  130  from external environmental effects, such as impacts. Examples of the molding member  140  may include Glop-top, epoxy molding compound, etc. 
       FIG. 3  is a cross-sectional view illustrating the semiconductor package in  FIG. 1  when the temperature of the package is increased. 
     The semiconductor package  100  may have a flat structure under a normal temperature. Referring to  FIG. 3 , when the temperature of the package is increased, the bimetal structure of the supporting substrate  120  may deform, and the central portion of the supporting substrate  120  may then be bent upwardly. Thus, the semiconductor chip  110  fixed to the upper surface  120   a  of the supporting substrate  120  may be bent upwardly as well. 
     When the semiconductor chip  110  is bent upwardly, tensile stresses may be applied to the bent semiconductor chip  110  in the first direction  115 . That is, the tensile stresses may be applied to the semiconductor substrate  112  in the lengthwise direction of the channel region  114   f . The tensile stresses may widen a gap between the lattices of the semiconductor substrate  112 . Therefore, the electronic carriers (electrons, in the case of NMOS transistors) may be more easily moved through the channel region  114   f  to increase a cell current of the cell transistor  114 . Further, although mobility of the electrons may be decreased due to the lattice vibration of the semiconductor substrate  112  in response to the temperature increase, the decreased mobility of the electrons may be at least partially compensated by the tensile stresses applied to the channel region  114   f.    
       FIG. 4  is a cross-sectional view illustrating a semiconductor package in accordance with further embodiments. 
     Referring to  FIG. 4 , a semiconductor package  200  of according to some embodiments may include a semiconductor chip  210 , a supporting substrate  220 , a compressing member  230  and a molding member  240 . 
     In the embodiments of  FIG. 4 , the semiconductor chip  210  may be substantially the same as the semiconductor chip  110  in the embodiments of  FIGS. 1 and 2 . Thus, any further illustrations with respect to the semiconductor chip  210  are omitted herein for brevity. 
     The supporting substrate  220  may have an upper surface  220   a  on which the semiconductor chip  210  may be fixed. In some embodiments, the supporting substrate  220  may include a printed circuit board (PCB) having wirings that transmit a voltage to the semiconductor substrate  210  and/or the cell transistors. Alternatively, the supporting substrate  220  may include a die without wirings for simply fixing the semiconductor chip  210 . 
     As mentioned above, the supporting substrate  220  may include the above-mentioned substrate. That is, the supporting substrate  220  may include a bimetal that may bend upwardly in response to a temperature increase. 
     The bimetal may include a first metal plate  220 - 1  having a first coefficient of thermal expansion, and a second metal plate  220 - 2  placed on the first metal plate  220 - 1  and having a second coefficient of thermal expansion higher than the first coefficient of thermal expansion, wherein the semiconductor chip  210  is mounted on the second metal plate  220 - 2  so that the second metal plate  220 - 2  is between the semiconductor chip  210  and the first metal plate  220 - 1 . The first metal plate  220 - 1  may include an alloy of nickel and iron. The second metal plate  220 - 2  may include an alloy of nickel, manganese and iron, an alloy of nickel, molybdenum and iron, an alloy of nickel, manganese and copper, etc. Therefore, a central portion  220   c  of the supporting substrate  220  may bend upwardly (i.e. toward the semiconductor chip  210 ) in response to a temperature increase. 
     The compressing member  230  may expand in response to a temperature increase to compress the supporting substrate  220 . In some embodiments, the compressing member  230  may include a material having a relatively high coefficient of thermal expansion. For example, the compressing member  230  may include a metal. 
     In some embodiments, the compressing member  230  may include a first compressing member  232  and a second compressing member  234 . Each of the first compressing member and the second compressing member may have a relatively high coefficient of thermal expansion. For example, the first compressing member and/or the second compressing member may have a coefficient of thermal expansion that is higher than the coefficient of thermal expansion of the supporting substrate  220  and/or the molding member  240 . 
     The first compressing member  232  may make contact with both side surfaces  220   b  of the supporting substrate  220  along a first direction  215  that may be substantially the same as an arrangement direction of cell transistors on the semiconductor chip  210 . Although not depicted in  FIG. 4 , the first compressing member  232  may make contact with both edge portions of an upper surface of the supporting substrate  220  along the first direction. The second compressing member  234  may make contact with a central portion of a lower surface  220   d  of the supporting substrate  220 . 
     The first compressing member  232  and the second compressing member  234  may expand in response to a temperature increase to compress the both side surfaces  220   b  and the central portion of the lower surface  220   d  of the supporting substrate  220 . Thus, a central portion  220   c  of the supporting substrate  220  may bend upwardly in response to the temperature increase. 
     Alternatively, the compressing member  230  may include only the first compressing member  232 . In this case, only the first compressing member  232  may compress the supporting substrate  220  to bend the central portion  220   c  of the supporting substrate  220  upwardly. 
     The molding member  240  may surround the semiconductor chip  210 , the supporting substrate  220  and the compressing member  230 . The molding member  240  may protect the semiconductor chip  210 , the supporting substrate  220  and the compressing member  230  from external environmental effects such as impacts. Examples of the molding member  240  may include Glop-top, epoxy molding compound, etc. 
       FIG. 5  is a cross-sectional view illustrating the semiconductor package in  FIG. 4  when the temperature is increased. 
     The semiconductor package  200  may have a flat structure under a normal temperature. Referring to  FIG. 5 , when the temperature of the package is increased, the compressing member  230  may expand and the central portion  220   c  of the supporting substrate  220  may then bent upwardly. Thus, the semiconductor chip  210  fixed to the upper surface  220   a  of the supporting substrate  220  may be bent upwardly. 
     When the semiconductor chip  210  is bent upwardly, tensile stresses may be applied to the bent semiconductor chip  210  in the first direction  215 . That is, the tensile stresses may be applied to a semiconductor substrate of the semiconductor chip  210  in a lengthwise direction of a channel region. The tensile stresses may widen a gap between the lattices of the semiconductor substrate. Therefore, the electronic carriers in the device may be more easily moved through the channel region, which may increase a cell current of the cell transistor. Further, although mobility of the electrons may be decreased due to the lattice vibration of the semiconductor substrate in response to the temperature increase, the decreased mobility of the electrons may be at least partially compensated by the tensile stresses. 
       FIG. 6  is a cross-sectional view illustrating a semiconductor package in accordance with some embodiments, and  FIG. 7  is a cross-sectional view illustrating a semiconductor chip in the semiconductor package in  FIG. 6 . 
     Referring to  FIGS. 6 and 7 , a semiconductor package  300  of this example embodiment may include a semiconductor chip  310 , a supporting substrate  320 , a supporting member  330  and a molding member  340 . 
     The semiconductor chip  310  may include a semiconductor substrate  312  and cell transistors  314  formed on the semiconductor substrate  312 . 
     The cell transistor  314  may include a tunnel oxide layer  314   a , a floating gate electrode  314   b , a dielectric layer  314   c , a control gate electrode  314   d , source/drain regions  314   e  and a channel region (not shown) that extends in a first direction that is perpendicular to a second direction  325  illustrated in  FIG. 7  (i.e., the channel region extends in a direction that is normal to the plane of the drawing). 
     In the embodiments of  FIGS. 6 and 7 , the semiconductor substrate  312  the tunnel oxide layer  314   a , the floating gate electrode  314   b , the dielectric layer  314   c , the control gate electrode  314   d , the source/drain regions  314   e  and the channel region may be substantially the same as the semiconductor substrate  112 , the tunnel oxide layer  114   a , the floating gate electrode  114   b , the dielectric layer  114   c , the control gate electrode  114   d , the source/drain regions  114   e  and the channel region  114   f  in  FIGS. 1 and 2 , respectively. Thus, any further illustrations with respect to the semiconductor substrate  312 , the tunnel oxide layer  314   a , the floating gate electrode  314   b , the dielectric layer  314   c , the control gate electrode  314   d , the source/drain regions  314   e  and the channel region are omitted herein for brevity. 
     The supporting substrate  320  may include a bimetal. The bimetal may include a first metal plate  320 - 1  having a first coefficient of thermal expansion, and a second metal plate  320 - 1  placed on the first metal plate and having a second coefficient of thermal expansion lower than the first coefficient of thermal expansion, wherein the semiconductor chip  310  is mounted on the second metal plate  320 - 2  so that the second metal plate  320 - 2  is between the semiconductor chip  310  and the first metal plate  320 - 1 . Therefore, the supporting substrate  320  may be substantially the same as the supporting substrate  120  in  FIGS. 1 and 2  except that a central portion  320   c  of the supporting substrate  320  may bend downwardly (i.e. away from the semiconductor chip  310 ) in response to a temperature increase. 
     The supporting member  330  may be substantially the same as the supporting member  130  in  FIGS. 1 and 2  except that the supporting member  330  may support both side surfaces  320   b  of the supporting substrate  320  along a second direction  325  that is substantially perpendicular to a first direction in which the channel region extends. 
     The molding member  340  may be substantially the same as the molding member  140  in  FIGS. 1 and 2 . 
       FIG. 8  is a cross-sectional view illustrating the semiconductor package in  FIG. 6  when a temperature is increased. 
     The semiconductor package  300  may have a flat structure under a normal temperature. Referring to  FIG. 8 , when the temperature of the package  300  is increased, the bimetal structure of the supporting substrate  320  may be bent and the central portion  320   c  of the supporting substrate  320  may then bend downwardly, away from the semiconductor chip  310 . Thus, the semiconductor chip  310  fixed to the upper surface of the supporting substrate  320  may bend downwardly. 
     When the semiconductor chip  310  bends downwardly, compressive stresses may be applied to the bent semiconductor chip  310  in the second direction  325 . That is, the compressive stresses may be applied to the semiconductor substrate  312  in the second direction substantially perpendicular to in the lengthwise direction of the channel region. Accordingly, tensile stresses may be generated in the lengthwise direction of the channel region by the compressive stresses applied in the second direction  325 . 
     The tensile stresses may widen a gap between the lattices of the semiconductor substrate  312 . Therefore, the electrons as the carriers may be easily moved through the channel region to increase a cell current of the cell transistor  314 . Further, although mobility of the electrons may be decreased due to the lattice vibration of the semiconductor substrate  312  in response to the temperature increase, the decreased mobility of the electrons may be at least partially compensated by the tensile stresses applied to the channel region. 
       FIG. 9  is a cross-sectional view illustrating a semiconductor package in accordance with some further embodiments. 
     Referring to  FIG. 9 , a semiconductor package  400  of according to some embodiments includes a semiconductor chip  410 , a supporting substrate  420 , a compressing member  430  and a molding member  440 . 
     In the embodiments of  FIG. 9 , the semiconductor chip  410  may be substantially the same as the semiconductor chip  410  in  FIGS. 1 and 2 . Thus, any further illustrations with respect to the semiconductor chip  410  are omitted herein for brevity. 
     The supporting substrate  420  may be substantially the same as the supporting substrate  320  in  FIGS. 6 and 7  except that a central portion  420   c  of the supporting substrate  420  may bend downwardly (i.e., away from the semiconductor chip  410 ) in response to a temperature increase. 
     The compressing member  430  may expand in response to a temperature increase to compress the supporting substrate  420 . In the embodiments of  FIG. 9 , the compressing member  430  may include a material having a high coefficient of thermal expansion. For example, the compressing member  430  may include a metal. 
     In the embodiments of  FIG. 9 , the compressing member  430  may include a first compressing member  432  and a second compressing member  434 . 
     The first compressing member  432  may make contact with both side surfaces  420   b  of the supporting substrate  420  along a second direction  425  that is substantially perpendicular to a first direction that corresponds to an arrangement direction of cell transistors on the semiconductor chip  410 . Although not depicted in  FIG. 9 , the first compressing member  432  may make contact with both edge portions of a lower surface of the supporting substrate  420  along the second direction  425 . The second compressing member  434  may make contact with a central portion of an upper surface  420   a  of the supporting substrate  420  and/or with the semiconductor chip  410 , as shown in  FIG. 9 . 
     The first compressing member  432  and the second compressing member  434  may expand in response to the temperature increase to compress the both side surfaces  420   b  and the central portion of the upper surface  420   a  of the supporting substrate  420 . Thus, a central portion  420   c  of the supporting substrate  420  may be bent downwardly (i.e., away from the semiconductor chip  410 ). 
     Alternatively, the compressing member  430  may include only the first compressing member  432 , in which case, only the first compressing member  432  may compress the supporting substrate  420  to bend the central portion  420   c  of the supporting substrate  420  downwardly. 
     The molding member  440  may be substantially the same as the molding member  240  illustrated in  FIGS. 4 and 5 . 
       FIG. 10  is a cross-sectional view illustrating the semiconductor package in  FIG. 9  when a temperature is increased. 
     The semiconductor package  400  may have a flat structure under a normal temperature. Referring to  FIG. 10 , when the temperature of the package  400  is increased, the compressing member  430  may expand, and the central portion  420   c  of the supporting substrate  420  may then bend downwardly. Thus, the semiconductor chip  410  fixed to the upper surface of the supporting substrate  420  may be bent downward. 
     When the semiconductor chip  410  is bent downward, compressive stresses may be applied to the bent semiconductor chip  410  in the second direction  425 . That is, the compressive stresses may be applied to the semiconductor substrate of the semiconductor chip in the second direction  425  that is substantially perpendicular to the lengthwise direction of the channel region, which may result in tensile stresses being generated in the lengthwise direction of the channel region. 
     The tensile stresses may widen a gap between the lattices of the semiconductor substrate. Therefore, the electronic carriers in the device may be more easily moved through the channel region, which can thereby increase a cell current of the cell transistor. Further, although mobility of the electrons may be decreased due to the lattice vibration of the semiconductor substrate in response to the temperature increase, the decreased mobility of the electrons may be at least partially compensated by the tensile stresses. 
       FIGS. 11A to 11C  are cross-sectional views illustrating methods of manufacturing the semiconductor package illustrated in  FIG. 1 . 
     Referring to  FIG. 11A , the semiconductor chip  110  and the supporting substrate  120  may be provided. 
     In some embodiments, the semiconductor chip  110  may be manufactured by forming the cell transistors  114  on the semiconductor substrate  112 . 
     In some embodiments, the semiconductor substrate  112  may include a silicon substrate, a silicon-germanium substrate, a silicon-on-insulator substrate, or any other suitable substrate. For example, the semiconductor substrate  112  may have a &lt;100&gt; crystal direction. Alternatively, the semiconductor substrate  112  may have a &lt;110&gt; crystal direction. 
     The cell transistors  114  may be formed on an upper surface of the semiconductor substrate  112  The cell transistors  112  may have a string structure arranged in a first direction  115 . For example, when the semiconductor substrate  110  has the &lt;100&gt; crystal direction, the cell transistors  114  may have a string structure arranged in the &lt;100&gt; direction. Alternatively, when the semiconductor substrate  110  has the &lt;110&gt; crystal direction, the cell transistors  114  may have a string structure arranged in the &lt;110&gt;direction inclined to a &lt;100&gt; plane by about 45°. That is, the first direction  115  may be substantially the same as the &lt;100&gt; direction. 
     In some embodiments, a tunnel oxide layer, a floating gate electrode, a dielectric layer and a control gate electrode may be sequentially formed on the semiconductor substrate  112  to form a gate structure. Impurities may be implanted into the semiconductor substrate  112  adjacent to the gate structure to form source/drain regions and a channel region between the adjacent source/drain regions. 
     As a result, cell transistors including the tunnel oxide layer, the floating gate electrode, the dielectric layer, the control gate electrode, the source/drain regions and the channel region may be formed. 
     In some embodiments, the supporting substrate  120  may include a bimetal. The bimetal may include a first metal plate  120 - 1  having a first coefficient of thermal expansion, and a second metal plate  120 - 2  placed on the first metal plate  120 - 1  and having a second coefficient of thermal expansion higher than the first coefficient of thermal expansion. 
     The semiconductor chip  110  may then be fixed to an upper surface  120   a  of the supporting substrate  120 . For example, the semiconductor chip  110  may be fixed to an upper surface  120   a  of the second metal plate  120 - 2  of the supporting substrate  120 , opposite the first metal plate  120 - 1 . In some embodiments, the semiconductor chip  110  may be fixed to the supporting substrate  120  using an adhesive. 
     Referring to  FIG. 11B , the supporting member  130  may make contact with the both side surfaces  120   b  of the supporting substrate  120  along a direction substantially the same as the first direction  115 , i.e., the arrangement direction of the cell transistors. In some embodiments, the supporting member  130  may include a material having a low coefficient of thermal expansion that may not substantially expand in response to a temperature increase. Alternatively, the supporting member  130  may include a material having a high coefficient of thermal expansion that may expand in response to a temperature increase. Thus the supporting member  130  may compress both side surfaces  120   b  of the supporting substrate  120 . As a result, because the supporting member  130  may support the both side surfaces  120   b  of the supporting substrate  120 , the bending of the supporting substrate  120  may be enhanced 
     Alternatively, the supporting substrate  120  may be bent without use of the supporting member  130 . 
     Referring to  FIG. 11C , the semiconductor chip  110 , the supporting substrate  120  and the supporting member  130  may be surrounded by a molding material such as Glop-top, epoxy molding compound, etc. The molding material may be cooled to form the molding member  140 . The molding member  140  may protect the semiconductor chip  110 , the supporting substrate  120  and the supporting member  130  from external environmental effects, such as impacts. 
     As a result, the semiconductor package  100  including the semiconductor chip  110 , the supporting substrate  120 , the supporting member  130  and the molding member  140  may be completed. 
       FIGS. 12A to 12C  are cross-sectional views illustrating methods of manufacturing the semiconductor package in  FIG. 4 . 
     Referring to  FIG. 12A , the semiconductor chip  210  and the supporting substrate  220  may be provided. 
     In some embodiments, the semiconductor chip  210  may be manufactured by forming the cell transistors  214  on the semiconductor substrate  212 . Here, processes for forming the cell transistors  214  may be substantially the same as those for forming the cell transistors  114  illustrated with reference to  FIG. 11A . 
     In some embodiments, the supporting substrate  220  may include a PCB, a die, etc. Further, the supporting substrate  220  may include a bimetal. 
     The semiconductor chip  210  may then be fixed to the upper surface of the supporting substrate  220 . In some embodiments, the semiconductor chip  210  may be fixed to the supporting substrate  220  using an adhesive. 
     Referring to  FIG. 12B , the first supporting member  232  may make contact with the both side surfaces  220   b  of the supporting substrate  220  along a direction  245  substantially the same as the first direction, i.e., the arrangement direction of the cell transistors  214 . Although not depicted in drawings, the first compressing member  232  may make contact with both edge portions of an upper surface of the supporting substrate  220  along the first direction. The second compressing member  234  may then make contact with a central portion of a lower surface  220   d  of the supporting substrate  220 . 
     The compressing member  230  including the first compressing member  232  and the second compressing member  234  may expand in response to the temperature increase to compress the supporting substrate  220 . In some embodiments, the compressing member  230  may include a material having a relatively high coefficient of thermal expansion. For example, the compressing member  230  may include a metal. 
     The first compressing member  232  and the second compressing member  234  may expand in response to the temperature increase to compress the both side surfaces  220   b  and the central portion of the lower surface  220   d  of the supporting substrate  220 . Thus, a central portion  220   c  of the supporting substrate  220  may bend upwardly in response to the temperature increase. 
     Referring to  FIG. 12C , the semiconductor chip  210 , the supporting substrate  220  and the compressing member  230  may be surrounded by a molding material such as Glop-top, epoxy molding compound, etc. The molding material may be cooled to form the molding member  240 . The molding member  240  may protect the semiconductor chip  210 , the supporting substrate  220  and the supporting member  230  from external environmental effects, such as impacts. 
     As a result, the semiconductor package  200  including the semiconductor chip  210 , the supporting substrate  220 , the compressing member  230  and the molding member  240  may be completed. 
     Method of manufacturing the semiconductor package  300  illustrated in  FIG. 6  may be substantially similar to the methods of manufacturing the semiconductor package  100  illustrated with reference to  FIGS. 11A to 11C , except that the supporting substrate  320  may have the bimetal configured to be bent downwardly (i.e. away from the semiconductor chip  310 ) in response to a temperature increase. 
     Further, methods of manufacturing the semiconductor package  400  illustrated in  FIG. 9  may be substantially similar to the methods of manufacturing the semiconductor package  200  illustrated with reference to  FIGS. 12A to 12C , except that the first compressing member  432  may make contact with the both side surfaces and/or the both edge portions of the lower surface of the supporting substrate  420  along the second direction, and the second compressing member  434  may make contact with the central portion of the upper surface of the supporting substrate  420 . 
     According to some example embodiments, the flat supporting substrate may be bent in response to a temperature increase, which may cause tensile stresses to be applied to to the semiconductor chip along the arrangement direction of the cell transistors, i.e., in a lengthwise direction of the channel region. Because the tensile stresses may widen a gap between lattices in a channel region, mobility of carriers passing through the channel region may be increased. As a result, a low mobility of the carriers caused by the temperature increase may be at least partially compensated. 
     In the drawings and specification, there have been disclosed typical embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.