Patent Publication Number: US-2005133785-A1

Title: Device and method for detecting the overheating of a semiconductor device

Description:
CLAIM FOR PRIORITY  
      This application claims the benefit of priority to German Application No. 103 55 333.9, which was filed in the German language on Nov. 27, 2003, the contents of which are hereby incorporated by reference.  
      The invention relates to a device and a method for detecting the overheating of a semiconductor device.  
      Semiconductor devices, e.g. appropriate, integrated (analog or digital) computing circuits, semiconductor memory devices such as functional memory devices (PLAs, PALs, etc.) and table memory devices (e.g. ROMs or RAMs, in particular SRAMs and DRAMs, e.g. SDRAMs), etc. are subject to comprehensive tests in the course of their manufacturing process as well as subsequent to their manufacturing.  
      For instance, even before all the desired processing steps have been performed on the wafer (i.e. already in a semifinished state of the semiconductor devices), the (semifinished) devices (that are still being on the wafer) may, at one or a plurality of testing stations, be subject to appropriate testing methods (e.g. so-called kerf measurements at the wafer scrib frame) by means of one or a plurality of testing apparatuses.  
      After the finishing of the semiconductor devices (i.e. after performing all the wafer processing steps), the semiconductor devices may be subject to further testing methods at one or a plurality of (further) testing stations—for instance, the finished devices—that are still being on the wafer—may, by means of appropriate (further) testing apparatuses, be tested appropriately (“wafer tests”).  
      After the sawing (or scribing, and breaking, respectively) of the wafer, the devices that are then available as individual devices and are loaded into so-called carriers may be subject to appropriate further testing methods at one or a plurality of (further) testing stations.  
      Correspondingly, one or a plurality of further tests may (at corresponding further testing stations, and by using corresponding, further testing apparatuses) be performed e.g. after the installation of the semiconductor devices in the corresponding semiconductor device housings, and/or e.g. after the installation of the semiconductor device housing (along with the respectively incorporated semiconductor devices) in appropriate electronic modules (so-called module tests), etc.  
      Semiconductor devices, e.g. SDRAMs, react sensitively to strong heating.  
      By being heated beyond particular threshold temperatures, a semiconductor device may be damaged irreversibly or may be destroyed, respectively.  
      Such damages may e.g. occur in the course of the semiconductor device manufacturing process, but, for instance, also after the manufacturing only, e.g. during the soldering of the corresponding device, or during operation.  
      It is in particular partial damages that can not or only with relatively high effort be detected by means of the above-mentioned testing methods.  
      It is an object of the invention to provide a novel device and a novel method for detecting the overheating of a semiconductor device.  
      This and further objects are achieved by the subject matters of claims  1  and  20 .  
      Advantageous further developments of the invention are indicated in the subclaims.  
      In accordance with a basic idea of the invention, a device for detecting the overheating of a semiconductor device is provided, said device comprising a temperature measuring means changing its electric conductivity when the temperature of the semiconductor device changes.  
      Advantageously, the temperature measuring means is designed such that the change in the electric conductivity of the temperature measuring means occurring when the temperature of the semiconductor device changes is irreversible.  
      Thus, it is relatively easy to determine whether there is the risk that a semiconductor device was—temporarily—overheated and might thus have been damaged irreversibly or destroyed, respectively. 
    
    
      In the following, the invention will be explained by means of several embodiments and the enclosed drawing. The drawing shows:  
       FIG. 1   a  a schematic representation of a device provided with a semiconductor device for detecting the overheating of the semiconductor device, in accordance with a first embodiment of the invention, in a state before the semiconductor device has been subject to relatively high temperatures;  
       FIG. 1   b  a schematic representation of the device illustrated in  FIG. 1   a , in a state after the semiconductor device has been subject to relatively high temperatures;  
       FIG. 1   c  a top view of the device illustrated in  FIGS. 1   a  and  1   b , in the state illustrated in  FIG. 1   a  before the semiconductor device has been subject to relatively high temperatures;  
       FIG. 2   a  a schematic representation of a device provided with a semiconductor device for detecting the overheating of the semiconductor device, in accordance with a second embodiment of the invention, in a state before the semiconductor device has been subject to relatively high temperatures;  
       FIG. 2   b  a schematic representation of the device illustrated in  FIG. 2   a , in a state after the semiconductor device has been subject to relatively high temperatures;  
       FIG. 2   c  a top view of the device illustrated in  FIGS. 2   a  and  2   b , in the state illustrated in  FIG. 2   a  before the semiconductor device has been subject to relatively high temperatures;  
       FIG. 3   a  a sectional view of a device provided with a semiconductor device for detecting the overheating of the semiconductor device, in accordance with a third embodiment of the invention, in a state before the semiconductor device has been subject to relatively high temperatures;  
       FIG. 3   b  a sectional view of the device illustrated in  FIG. 3   a , in a state after the semiconductor device has been subject to relatively high temperatures;  
       FIG. 3   c  a top view of the device illustrated in  FIGS. 3   a  and  3   b , in the state illustrated in  FIG. 3   a  before the semiconductor device has been subject to relatively high temperatures; and  
       FIG. 3   d  a top view of the device illustrated in  FIGS. 3   a  and  3   b , in the state illustrated in  FIG. 3   b  after the semiconductor device has been subject to relatively high temperatures. 
    
    
       FIG. 1   a  shows a schematic, lateral sectional view of a device  1  provided with a semiconductor device for detecting the overheating of the semiconductor device, in accordance with a first embodiment of the invention, in a state before the semiconductor device has been subject to relatively high temperatures.  
      The overheating detection device  1  may, for instance, be arranged directly at the surface of a corresponding semiconductor device, or e.g. in the interior of the semiconductor device.  
      The semiconductor device may, for instance, be an appropriate, integrated (analog or digital) computing circuit, or e.g. a semiconductor memory device such as a functional memory device (PLA, PAL, etc.), or a table memory device (e.g. a ROM or a RAM, in particular a SRAM or a DRAM, e.g. a SDRAM), and/or a combined computing circuit/memory device, etc.  
      In accordance with  FIG. 1   a , the overheating detection device  1  comprises two contact elements  2   a ,  2   b , with a corresponding measuring section  3  positioned therebetween.  
      As is illustrated in  FIG. 1   c , the cross-section of the contact elements  2   a ,  2   b  may (viewed from the top) e.g. be rectangular, or e.g. also circular, oval, etc.  
      Again referring to  FIG. 1   a , the measuring section  3 —positioned in a region below and between the contact elements  2   a ,  2   b —is manufactured of an appropriate semiconductor material, e.g. silicon (e.g. of a correspondingly similar or identical basic material as the remaining portion of the semiconductor device).  
      A partial region  3 ′ of the measuring section  3 —positioned substantially in the middle between the contact elements  2   a ,  2   b —is (relatively strongly) doped, e.g. relatively strongly n-doped or relatively strongly p-doped, i.e. is of relatively good conductivity.  
      As compared to this, the two partial regions  3 ″ of the measuring section—positioned directly below the contact elements  2   a ,  2   b , or adjacent to or contacting, respectively, the contact elements  2   a ,  2   b —are undoped (or, alternatively: only weakly n- or p-doped), i.e. are of no or only poor conductivity.  
      With the doped partial region  3 ′, doping may be largest at or near an imagined plane A passing perpendicularly through the partial region  3 ′ (i.e. at a central region), and may continue decreasing with the increasing lateral distance from this imagined plane A.  
      The doped partial region  3 ′ may, for instance, be generated by a doping being injected locally into the—initially undoped—region  3  (e.g. by means of conventional diffusion methods, (ion) implantation methods, etc.).  
      As results from  FIG. 1   a  and  FIG. 1   c , the width w 1  of the doped partial region  3 ′ is—initially—so small that—laterally—a certain distance a 1  exists between the lateral edge regions of the partial region  3 ′ and the contact elements  2   a ,  2   b  (initial state).  
      Thus, the—conductive—partial region  3 ′ is in the initial state (due to the respective non-conductive partial region  3 ″ positioned, in accordance with  FIG. 1   a  and  FIG. 1   c , between the partial region  3 ′ and the respective contact element  2   a ,  2   b ) separated electrically from the contact elements  2   a ,  2   b.    
      When the semiconductor device is heated, the outer limit or the respective lateral edge region, respectively, of the doped partial region  3 ′ is shifted—due to corresponding diffusion of the doping atoms contained in the partial region  3 ′—laterally in the direction of the contact elements  2   a ,  2   b  (as is illustrated in  FIG. 1   a  by the arrows B).  
      As is illustrated in  FIG. 1   b , the dimensions of the partial region  3 ′, the doping intensity, the dimensions of the contact elements  2   a ,  2   b , etc. are appropriately chosen such that, when the temperature of the semiconductor device exceeds a predetermined threshold temperature T (wherein the heating e.g. has to prevail for a certain, relatively short period t only, e.g. t&lt;5 sec, or e.g. t&lt;1 sec, or t&lt;0.5 sec), the outer limit or the respective lateral edge region, respectively, of the doped partial region  3 ′ is shifted laterally to such an extent that the partial region  3 ′ gets—at least partially (here e.g.: at a region C)—into contact with the lower limiting region of the respective contact element  2   a ,  2   b.    
      Thus—after the overheating of the semiconductor device (exceeding of the threshold temperature T)—the contact element  2   a , the partial region  3 ′, and the contact element  2   b  are—irreversibly—electrically connected with one another (2 nd  state).  
      The above-mentioned threshold temperature T is chosen such that from this temperature onwards there would be the risk of the semiconductor device being damaged irreversibly or destroyed, respectively.  
      The first and second contact elements  2   a ,  2   b  may, for instance, be connected directly by means of appropriate bonding wires, or e.g. indirectly by means of corresponding lines provides in or at the semiconductor device, to corresponding pins of the device housing accommodating the semiconductor device.  
      The first pin—that is connected with the first contact element  2   a —may e.g. be connected to a first terminal of a test device, and the second pin—that is connected with the second contact element  2   b —may e.g. be connected to a second test device terminal.  
      By applying an appropriate voltage between the first and the second test device terminals (and thus between the first and the second contact elements  2   a ,  2   b ), and subsequently measuring whether a corresponding current then flows between the contact elements  2   a ,  2   b  or not (or whether the intensity of the current flowing exceeds a predetermined threshold value), there may be determined whether no electrical connection exists between the contact elements  2   a ,  2   b  (initial state,  FIG. 1   a , “test passed”), or whether the contact elements  2   a ,  2   b —as explained above—are electrically connected with one another after the overheating of the semiconductor device (2 nd  state,  FIG. 1   b , “test not passed”), this indicating that the semiconductor device might have been damaged or destroyed due to overheating.  
       FIG. 2   a  shows a schematic, lateral sectional view of a device  11  provided with a semiconductor device for detecting the overheating of the semiconductor device, in accordance with a second embodiment of the invention, in a state before the semiconductor device has been subject to relatively high temperatures.  
      The overheating detection device  11  may, for instance, be arranged directly at the surface of a corresponding semiconductor device, or e.g. in the interior of the semiconductor device.  
      The semiconductor device may e.g. be an appropriate, integrated (analog or digital) computing circuit, or e.g. a semiconductor memory device such as a functional memory device (PLA, PAL, etc.), or a table memory device (e.g. a ROM or a RAM, in particular a SRAM or a DRAM, e.g. a SDRAM), and/or a combined computing circuit/memory device, etc.  
      The overheating detection device  11  comprises, in accordance with  FIG. 2   a , two contact elements  12   a ,  12   b  with a corresponding measuring section  13  positioned therebetween.  
      The contact elements  12   a ,  12   b  may e.g. (correspondingly similar as with the embodiment illustrated in  FIGS. 1   a ,  1   b , in particular correspondingly similar as illustrated in  FIG. 1   c ) have (viewed from the top) e.g. a rectangular, or e.g. a circular, oval, etc. cross-section.  
      As is illustrated in  FIG. 2   a , the measuring section  13 —positioned in a region below and between the contact elements  12   a ,  12   b —is manufactured of an appropriate semiconductor material, e.g. silicon (e.g. of a correspondingly similar or identical basic material as the remaining portion of the semiconductor device).  
      During the manufacturing of the overheating detection device  11 , the entire region of the measuring section  13  positioned below and between the contact elements  12   a ,  12   b  (e.g. the entire measuring section region) is first of all, e.g. by means of conventional diffusion methods, (ion) implantation methods, etc., relatively strongly doped, e.g. relatively strongly n-doped or relatively strongly p-doped, so that the entire measuring section region (or the entire measuring section  13 , respectively) is then of—relatively good—conductivity.  
      Subsequently, a partial region  13 ′ of the measuring section—positioned substantially in the middle between the contact elements  12   a ,  12   b —is, by means of appropriate, conventional method technologies, treated such that the above-mentioned semiconductor material changes from an initially non-amorphous, crystalline state to an amorphous state.  
      This may e.g. be effected by the partial region  13 ′ (e.g. —as illustrated in  FIG. 2   c —its upper limit region D) is—for a short period—irradiated from the top with a laser beam provided by a laser, and is thus heated very quickly very strongly, and subsequently cooled again very quickly very strongly.  
      The two partial regions  13 ′ of the measuring section  13 —positioned directly below the contact elements  12   a ,  12  or adjacent to or contacting the contact elements  12   a ,  12 , respectively—remain in the above-mentioned crystalline, i.e. conductive, state.  
      Since—as is illustrated in  FIGS. 2   a  and  2   c —the amorphous, and thus non-conductive partial region  13 ′ extends over the entire breadth b and the entire height h of the measuring section  13 —that is surrounded by non-conductive material—the crystalline, conductive partial region  13 ″ positioned, in the drawing according to  FIG. 2   a , at the left and contacting the contact element  12   a  is—by the non-conductive partial region  13 ′ positioned between the conductive partial regions  13 ″ electrically separated from the crystalline, conductive partial region  13 ″ positioned in the drawing at the right and contacting the contact element  12   b.    
      Thus—with the initial state of the overheating detection device  11  illustrated in  FIGS. 2   a  and  2   c —the contact element  12   a  is electrically separated from the contact element  12   b  by the non-conductive partial region  13 ′ positioned, in accordance with  FIGS. 2   a  and  2   c , between the conductive partial regions  13 ″.  
      If the semiconductor device is heated beyond a predetermined threshold temperature T (wherein the heating e.g. has to prevail for a certain, relatively short period t only, e.g. t&lt;5 sec, or e.g. t&lt;1 sec, or t&lt;0.5 sec), the amorphous structures prevailing in the partial region  13 ′ again change to corresponding crystalline structures, this rendering the partial region  13 ′ electroconductive (again).  
      Thus—after the overheating of the semiconductor device (exceeding of the threshold temperature T)—the contact element  12   a  and the contact element  12   b  are—irreversibly—electrically connected with one another (2 nd  state).  
      By an appropriate choice of the (semiconductor) materials, the dimensions of the partial region  13 ′, the duration and/or the intensity of the laser treatment, etc., the above-mentioned threshold temperature T may be modified or adjusted, respectively (on the exceeding of which the partial region  13 ′ becomes electroconductive (again) (or—for the test method explained in detail further below—becomes correspondingly conductive to such an extent that the test provides a result “not passed”).  
      The threshold temperature T may advantageously be chosen such that, from this temperature onwards, there would be the risk of the semiconductor device being irreversibly damaged or destroyed, respectively.  
      The first and second contact elements  12   a ,  12   b  may e.g. be connected directly by means of appropriate bonding wires, or e.g. indirectly by means of appropriate lines provided in or at the semiconductor device, to corresponding pins of the device housing accommodating the semiconductor device.  
      The first pin—that is connected with the first contact element  12   a —may e.g. be connected to a first terminal of a test device, and the second pin—that is connected with the second contact element  12   b —may e.g. be connected to a second test device terminal.  
      By applying an appropriate voltage between the first and the second test device terminals (and thus between the first and the second contact elements  12   a ,  12   b ), and subsequently measuring whether a corresponding current then flows between the contact elements  12   a ,  12   b  or not (or whether the intensity of the current flowing exceeds a predetermined threshold value), there may be determined whether no electrical connection exists between the contact elements  12   a ,  12   b  (initial state,  FIG. 2   a , “test passed”), or whether the contact elements  12   a ,  12   b —as explained above—are electrically connected with one another after the overheating of the semiconductor device (2 nd  state,  FIG. 2   b , “test not passed”), this indicating that the semiconductor device might have been damaged or destroyed due to overheating.  
       FIG. 3   a  shows a schematic, lateral sectional view of a device  21  provided with a semiconductor device for detecting the overheating of the semiconductor device, in accordance with a third embodiment of the invention, in a state before the semiconductor device has been subject to relatively high temperatures.  
      The overheating detection device  21 —in particular two contact elements  22   a ,  22   b  provided with this device, and a metal layer, in particular a softmetal layer  24  (of relatively good conductivity) positioned therebetween—may e.g. be arranged directly at the surface of the corresponding semiconductor device, or e.g. on a special substrate, or e.g. in the interior of the semiconductor device. The overheating detection device  21  is surrounded by non-conductive material, e.g.—undoped—silicon (e.g. a correspondingly similar or identical—undoped—basic material as with the remaining portion of the semiconductor device).  
      The semiconductor device may, for instance, be an appropriate, integrated (analog or digital) computing circuit, or e.g. a semiconductor memory device such as a functional memory device (PLA, PAL, etc.), or a table memory device (e.g. a ROM or a RAM, in particular a SRAM or a DRAM, e.g. a SDRAM), and/or a combined computing circuit/memory device, etc.  
      In the overheating detection device  21 —as is, for instance, illustrated in  FIG. 3   a —a corresponding measuring section  23  is formed by the two contact elements  12   a ,  12   b , and the metal layer  24  positioned therebetween.  
      As is illustrated in  FIG. 3   c , the contact elements  22   a ,  22   b  may (viewed from the top) e.g. be of rectangular, or e.g. also circular, oval, etc. cross-section.  
      Again referring to  FIG. 3   a , a region of the metal layer  24 —positioned at the left in the drawing—contacts the contact element  22   a , and a region of the metal layer  24 —positioned at the right in the drawing—contacts the contact element  22   b , with the metal layer  24  extending, in the present embodiment, with a substantially constant height h between the two contact elements  22   a ,  22   b.    
      As is illustrated in  FIG. 3   c , the metal layer  24  has a—relatively large—breadth b 1  in the area of or close to the contact elements  22   a ,  22   b , respectively.  
      In a region positioned roughly in the middle between the contact elements  22   a ,  22   b , the metal layer  24  is—relatively strongly—tapered, so that there the metal layer  24  has only a—relatively small—breadth b 2  that may only amount to less than the half, e.g. less than a third, or less than a fourth, of the breadth b 1  of the metal layer  24  at or close to the contact elements  22   a ,  22   b.    
      As results from  FIG. 3   a  and  FIG. 3   c , the (left) contact element  22   a  is (due to the above-explained design of the metal layer  24 ) connected electroconductively with the (right) contact element  22   b  via the metal layer  24  (initial state).  
      As is illustrated in  FIGS. 3   b  and  3   c , the dimensions of the metal layer  24 , the dimensions of the contact elements  22   a ,  22   b , and—in particular—the material forming the metal layer (metal or metal alloy, etc.) are appropriately chosen such that, when the temperature of the semiconductor device exceeds a predetermined threshold temperature T (wherein the heating has to prevail for a certain, relatively short period t only, e.g. t&lt;5 sec, or e.g. t&lt;1 sec, or t&lt;0.5 sec), the metal layer  24  is “melted apart”.  
      The above-mentioned threshold temperature T is chosen such that, from this temperature onwards, there would be the risk of the semiconductor device being damaged irreversibly or destroyed, respectively.  
      For adjusting the threshold temperature T, the material, in particular metal/alloy used for constructing the metal layer  24 , in particular may be chosen such that the melting point of the material is approximately identical to the above-mentioned threshold temperature T.  
      After the melting apart of the metal layer  24 —at the above-mentioned tapered region having merely the breadth b 2 —two separate metal layer parts  24   a ,  24   b —that are separated from each other electrically (by the air therebetween)—have, in accordance with  FIGS. 3   a  and  3   d , been generated from the original, one-piece metal layer  24 .  
      Thus—after the overheating of the semiconductor device (exceeding of the threshold temperature T)—the contact element  22   a  and the contact element  22   b  are—irreversibly—separated from one another electrically (2 nd  state).  
      By the above-described design of the metal layer  24  it is prevented that—after the metal layer  24  has been melted apart—the two single metal layer parts  24   a ,  24   b  that have been generated may combine with one another again (later).  
      This becomes possible in particular by the metal structure—here chosen by way of example and explained in detail above—with which the metal or alloy material, respectively, of the metal layer  24  is, in the melted-apart state, contracted—due to correspondingly acting capillary forces—to form the above-mentioned metal layer parts  24   a ,  24   b  at the two contact elements  22   a ,  22   b.    
      This effect can also be supported, for instance, by an appropriate choice of the material and/or the property of the substrate positioned directly below the metal layer  24  (and possibly being selected specifically), in particular by taking into account the wetting characteristics of the material used for the metal layer  24  on the substrate.  
      The first and second contact elements  22   a ,  22   b  may, for instance, be connected directly by means of appropriate bonding wires, or e.g. indirectly by means of appropriate lines provided in or at the semiconductor device, to corresponding pins of the device housing accommodating the semiconductor device.  
      The first pin—connected with the first contact element  22   a —may e.g. be connected to a first terminal of a test device, and the second pin—connected with the second contact element  22   b —may e.g. be connected to a second test device terminal.  
      By applying an appropriate voltage between the first and the second test device terminals (and thus between the first and the second contact elements  22   a ,  22   b ), and subsequently measuring whether a corresponding current then flows between the contact elements  22   a ,  22   b  or not, there may be determined whether an electrical connection exists—via the metal layer  24 —between the contact elements  22   a ,  22   b  (initial state,  FIG. 3   a , “test passed”), or whether the contact elements  22   a ,  22   b —as explained above—are electrically separated from one another after the overheating of the semiconductor device and the melting apart of the metal layer  24  effected thereby (2 nd  state,  FIG. 3   b , “test not passed”), this indicating that the semiconductor device might have been damaged or destroyed due to overheating.  
      Instead of every single one of the above-described overheating detection devices  1 ,  11 ,  21 , a plurality of—e.g. two, three, or more—overheating detection devices  1 ,  11 ,  21  (e.g. each constructed correspondingly similar as described above) may also be arranged on the same semiconductor device (each e.g. becoming electroconductive or non-conductive with the same or substantially the same threshold temperature T, or e.g. each with—possibly relatively strongly—different threshold temperatures T 1 , T 2 , T 3 , T 4 , etc. (so that—depending on the number of the different threshold temperatures T 1 , T 2 , T 3 , T 4  used—the temperature range (T 1 -T 2 , T 2 -T 3 , etc.) including that temperature to which the semiconductor device was maximally subjected may be determined for the semiconductor device)).  
      List of Reference Signs  
     
         
           1  overheating detection device  
           2   a  contact element  
           2   b  contact element  
           3  measuring section  
           3 ′ doped measuring section partial region  
           3 ″ undoped measuring section partial region  
           3 ″ undoped measuring section partial region  
           11  overheating detection device  
           12   a  contact element  
           12   b  contact element  
           13  measuring section  
           13 ′ amorphous measuring section partial region  
           13 ″ crystalline measuring section partial region  
           13 ″ crystalline measuring section partial region  
           21  overheating detection device  
           22   a  contact element  
           22   b  contact element  
           23  measuring section  
           24  soft metal layer