Abstract:
A method of manufacturing a semiconductor device including mounting semiconductor chips, each chip having pads, on respective areas of a front surface of an assembly substrate, electrically connecting corresponding terminals on a rear surface of the assembly substrate through wirings of the assembly substrate to the pads of the semiconductor chips, respective terminals and wirings electrically connected to a semiconductor chip being confined within the corresponding area of the assembly substrate on which the semiconductor chip is mounted, inputting test waveforms to the pads of the plurality of semiconductor chips through the corresponding terminals and wirings and testing the semiconductor chips, and, after the testing the semiconductor chips, cutting the assembly substrate with a rotating blade into pieces corresponding to the respective areas. The terminals and wirings connecting the terminals to the semiconductor chips are not cut by the rotating blade.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1) Field of the Invention  
         [0002]     The present invention relates to a test apparatus that tests a semiconductor integrated device for initial defect. More particularly, this invention relates to a burn-in test adapter and a burn-in test apparatus.  
         [0003]     2) Description of the Related Art  
         [0004]     Generally, it is examined before shipment whether the semiconductor chips are faulty before their shipment (hereafter, “initial defect”). The initial defect may occur in the semiconductor chips in the manufacturing process. Only the good semiconductor chips, which pass this examination, are shipped. The inspection of the initial defects of the semiconductor chips and malfunctions at the manufacturing steps of the semiconductor chips is conducted by a test called “burn-in test”. In this burn-in test, a semiconductor chip is put in a high temperature environment, e.g., 125° C. (degree centigrade), in which a voltage or a signal is applied to the semiconductor chip.  
         [0005]     A wafer, on which semiconductor chips are formed, is cut into pieces, then the semiconductor chips are assembled and finished as semiconductor integrated devices. The conventional burn-in test is conducted on these semiconductor devices. When performing the burn-in test, the semiconductor integrated devices are attached to a burn-in board, on which burn-in test wirings are provided, and a burn-in test input waveform is input through the input terminals of the respective semiconductor integrated devices.  
         [0006]     The conventional burn-in test has, however, the following disadvantage. Since the conventional burn-in test is conducted after the semiconductor chips are packaged into the semiconductor integrated devices, packaging steps and materials used at the packaging steps for the semiconductor integrated devices that are determined to be bad are wasted.  
         [0007]     To solve this disadvantage, Japanese Patent Application Laid-Open No. 4-312943 (see page 3) discloses performing the burn-in test before the semiconductor chips are assembled into semiconductor integrated devices. According to this publication, a burn-in test wiring and a burn-in test terminal are formed first on a burn-in test substrate (hereinafter, “sub-substrate”). A plurality of semiconductor chips thus cut off according to the chips are mounted on the sub-substrate, the burn-in test terminal is electrically connected to the pad of each semiconductor chip, thus conducting the burn-in test. After it is determined by such a burn-in test whether the semiconductor chips are good, the sub-substrate on which the semiconductor chips are mounted is cut off together with each of the semiconductor chips. Only the semiconductor chips on the sub-substrates that are determined as good chips are packaged, together with the sub-substrates, on a main substrate, and shipped as semiconductor integrated devices.  
         [0008]     According to the technology disclosed in the above-mentioned publication, the burn-in test is executed while mounting the semiconductor chips on the sub-substrate, and the sub-substrate is cut off together with each of the chips and mounted on the main substrate. Therefore, it is unnecessary to conduct a test to decide whether the product is good or bad (hereinafter, “GOOD/BAD test”) to the respective semiconductor chips after the chips are mounted on the main substrate, thus improving efficiency for the semiconductor chip GOOD/BAD test operation.  
         [0009]     However, since the sub-substrates are cut into pieces after the burn-in test, the sub-substrates can not be recycled. Therefore, it is necessary to form a burn-in test wiring and a burn-in test terminal for each semiconductor chip to be tested on the sub-substrate. As a result, the cost of the sub-substrate for mounting thereon semiconductor chips is disadvantageously pushed up.  
         [0010]     When the sub-substrate is cut into pieces, the wiring on the sub-substrate is also cut. As a result, the service life of a substrate cutting device such as a rotational blade is disadvantageously shortened, the cost of the burn-in test is disadvantageously pushed up, and cost for obtaining the semiconductor chips is disadvantageously pushed up.  
         [0011]     The burn-in test is conducted while a plurality of semiconductor chips are mounted on one sub-substrate. To increase the number of semiconductor chips to be measured at one time, there is disadvantageously no choice but increasing the size of the sub-substrate.  
       SUMMARY OF THE INVENTION  
       [0012]     It is an object of the present invention to solve at least the problems in the conventional technology.  
         [0013]     The burn-in test adapter according to one aspect of the present invention includes a wiring in such a manner that, when an assembly substrate is attached to the burn-in test adapter, the wiring makes an electrical contact with the terminal of each of semiconductor chips on the assembly substrate; and a burn-in test terminal electrically connected to the wiring and receiving a burn-in test waveform.  
         [0014]     The burn-in test apparatus according to one aspect of the present invention includes the burn-in test adapter, which is rectangular and the burn-in test terminal is arranged on one of the four sides, a socket that holds the burn-in test adapter at the side on which the burn-in test terminal is arranged and that is electrically connected to the burn-in test terminal; and a burn-in board that holds the socket and that includes a wiring that is electrically connected to the socket, wherein the wiring receives the burn-in test waveform.  
         [0015]     The other objects, features and advantages of the present invention are specifically set forth in or will become apparent from the following detailed descriptions of the invention when read in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  illustrates the configuration of a burn-in test adapter according to the present invention;  
         [0017]      FIG. 2  illustrates the configuration of a burn-in test adapter according to a first embodiment according to the present invention;  
         [0018]      FIG. 3  illustrates the configuration of a burn-in test adapter according to a second embodiment according to the present invention; and  
         [0019]      FIG. 4  illustrates the configuration of a burn-in test apparatus according to a third embodiment according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]     Exemplary embodiments of a burn-in test adapter and a burn-in test apparatus according to the present invention are explained below in detail with reference to the accompanying drawings. It should be noted that these embodiments are not intended to limit the present invention.  
         [0021]     A first embodiment of the present invention will be explained with reference to  FIGS. 1 and 2 .  FIG. 1  is a top view of a schematic configuration of the burn-in test adapter according to the present invention.  FIG. 2  is a side view of the schematic configuration of a burn-in test adapter according to a first embodiment of the present invention.  
         [0022]     A plurality of semiconductor chips  11   a ,  11   b ,  11   c ,  11   d  are mounted on and electrically connected to one surface (hereinafter, “front surface”) of an assembly substrate  10 . The front surface is a surface of the assembly substrate  10  that is a surface (hereinafter, “rear surface”) that is opposite to a surface that comes in contact with a burn-in test adapter  20   a . Burn-in test waveform input terminals  23   a ,  23   b ,  23   c ,  23   d  are arranged on the rear surface of the assembly substrate  10 . The burn-in test waveform input terminals  23   a ,  23   b ,  23   c ,  23   d  are electrically connected to the semiconductor chips  11   a ,  11   b ,  11   c ,  11   d , respectively, through wirings. The semiconductor chips  11   a ,  11   b ,  11   c ,  11   d  are collectively referred to as semiconductor chips  11 , and the burn-in test waveform input terminals  23   a ,  23   b ,  23   c ,  23   d  are collectively referred to as burn-in test waveform input terminals  23 .  
         [0023]     The burn-in test adapter  20   a  is a device that examines the semiconductor chips  11 . The assembly substrate  10  is detachable from the burn-in test adapter  20   a . A burn-in test terminal  21  and a burn-in test wiring  22  are arranged on one surface (hereinafter, “front surface”) of the burn-in test adapter  20   a . The front surface of the burn-in test adapter  20   a  is a surface that comes in contact with the assembly substrate  10 .  
         [0024]     The burn-in test terminal  21  electrically connects a not shown burn-in test input waveform generator to the burn-in test adapter  20   a.    
         [0025]     The burn-in test wiring  22  is provided on the burn-in test adapter  20   a  so as to propagate an input waveform from the burn-in test input waveform generator to the burn-in test waveform input terminals  23  of the assembly substrate  10  when the assembly substrate  10  is attached to this burn-in test adapter  20   a . The burn-in test wiring  22  electrically connects the burn-in test terminal  21  to the burn-in test waveform input terminals  23 . The burn-in test wiring  22  extended from the burn-in test terminal is constituted to be branched halfway along the wiring and the branched wirings are connected to the burn-in test waveform input terminals  23 , individually.  
         [0026]     One burn-in test wiring  22  is provided to be connected to the burn-in test waveform input terminals  23  since the burn-in test waveform input terminals  23 , each of which is coupled to one pad on each semiconductor chip  11 , are connected to the burn-in test wiring  22 .  
         [0027]     The explanation given above assumes that each semiconductor chip  11  provided with one pad. However, each semiconductor chip  11  may be provided with a plurality of pads and these pads may be electrically connected to the burn-in test waveform input terminals  23 . When each semiconductor chip  11  is provided with a plurality of pads, the number of burn-in test wirings  22  is equal to that of the pads, and each burn-in test waveform input terminal  23  is electrically connected to a plurality of burn-in test wirings  22 . The burn-in test wirings  22  are extended as a bundle from the burn-in test terminal  21  to the burn-in test waveform input terminals  23  so as not to contact one another. Just before being input to the burn-in test waveform input terminals  23 , the wiring  22  is branched into a plurality of wirings and the branched wirings are electrically connected to the burn-in test waveform input terminals  23 , respectively.  
         [0028]     The semiconductor chips  11  and the burn-in test waveform input terminals  23  are arranged on the assembly substrate  10  so as to be electrically connected on a one-by-one correspondence such as the semiconductor chip  11   a  to the burn-in test waveform input terminal  23   a , the semiconductor chip  11   b  to the burn-in test waveform input terminal  23   b , the semiconductor chip  11   c  to the burn-in test waveform input terminal  23   c  and so on.  
         [0029]     Wirings are provided on the rear surface and inside of the assembly substrate  10  in order to connect the burn-in test waveform input terminals  23  to the semiconductor chips  11 , respectively. By connecting the burn-in test adapter  20   a  to the assembly substrate  10 , the burn-in test terminal  21 , the burn-in test wiring  22 , the burn-in test waveform input terminals  23 , the assembly substrate  10 , and the semiconductor chips  11  are electrically connected.  
         [0030]     By thus providing the burn-in test adapter  20   a , it is possible to conduct a burn-in test to the semiconductor chips  11  without providing the burn-in test wiring or the burn-in test terminal on the assembly substrate  10 .  
         [0031]     A burn-in test method conducted while using the burn-in test adapter in the first embodiment will next be explained. A wafer from which a plurality of semiconductor chips  11  are formed is cut into pieces according to the semiconductor chips  11 , and the semiconductor chips  11  are mounted on the assembly substrate  10  so as to be electrically connected thereto. The assembly substrate  10  on which the semiconductor chips  11  are mounted is electrically connected to the burn-in test adapter  20   a.    
         [0032]     The burn-in test adapter  20   a  is then connected to the burn-in test input waveform generator. The semiconductor chips  11  are put in a high temperature environment, e.g., 125° C., and a burn-in test input waveform is generated from the burn-in test input waveform generator. The burn-in test input waveform generated from the burn-in test input waveform generator is input to the semiconductor chips  11  through the burn-in test terminal  21 , the burn-in test wiring  22 , and the respective burn-in test waveform input terminals  23 . The semiconductor chips  11  into which the burn-in test input waveform is thus input are kept in this state for a predetermined time. Thereafter, the assembly substrate  10  is detached from the burn-in test adapter  20   a . Since this burn-in adapter  20   a  is not formed integrally with the assembly substrate  10 , it can be recycled without being cut off and used for the next burn-in test.  
         [0033]     The assembly substrate  10  is then cut into pieces so as to be separated according to the respective semiconductor chips  11 . Since the burn-in test wiring  22  is not provided on the assembly substrate  10 , it is unnecessary to cut off a metal wiring during the cutoff of the assembly substrate  10 . Finally, the assembly substrate  10  is cut into pieces so as to be separated according to the respective chips, and it is determined whether each chip is good in a later test to detect an initial defect thereof. Only the substrates  10  determined to be good are moved to the next step and packaged.  
         [0034]     As explained above, according to the first embodiment, the burn-in test adapter  20   a  is constituted to include the burn-in test wiring  22  and the burn-in test terminal  21 . Therefore, it is not necessary to form the burn-in test wiring and the burn-in test terminal on the assembly substrate  10 . As a result, cost reduction becomes possible.  
         [0035]     Since the burn-in test adapter  20   a  can be recyclable, it is possible to reduce the cost of the burn-in test. Further, since it is unnecessary to cut the burn-in test wiring  22  on the burn-in test adapter into pieces, the service life of the substrate cutting device such as a rotational blade or the like to be used for cutting is not shortened.  
         [0036]     Consequently, by employing the burn-in test adapter  20   a , it is possible to obtain the burn-in test apparatus that can conduct a test at low cost.  
         [0037]     A second embodiment of the present invention is explained below with reference to  FIG. 3 . The second embodiment is characterized by providing a circuit, which increases the number of input signals that can be applied during a burn-in test, on a burn-in test adapter.  
         [0038]      FIG. 3  is a schematic diagram of the configuration of a burn-in test adapter  20   b  according to the second embodiment. Among the elements shown in  FIG. 3 , those that have same or similar configuration or same of similar function as those elements shown in  FIG. 1  have been denoted by the same reference symbols and their explanation is omitted.  
         [0039]     The burn-in test adapter  20   b  consists of a plurality of burn-in test input waveform generation circuits  24   a ,  24   b ,  24   c ,  24   c , the burn-in test wiring  22 , and the burn-in test terminal  21 . Each of the burn-in test input waveform generation circuits  24  generates, for example, a plurality of burn-in test input waveforms from one burn-in test input waveform. The burn-in test input waveform generation circuits  24   a ,  24   b ,  24   c ,  24   c  are collectively referred to as burn-in test input waveform generation circuits  24 .  
         [0040]     The burn-in test input waveform generation circuits  24  are arranged on the burn-in test adapter  20   b  at positions at which the circuits  24  are electrically connected to the burn-in test waveform input terminals  23  near thereof, respectively when the assembly substrate  10  is attached to the burn-in test adapter  20   b . The circuits  24  as many as the semiconductor chips  11  that can be arranged on the burn-in test adapter  20   b  are arranged on the burn-in test adapter  20   b . By so arranging, the burn-in test input waveform generation circuits  24  can generate burn-in test input waveforms to the semiconductor chips, respectively.  
         [0041]     It is normally known that if a plurality of pads are used for the burn-in tests conducted to the semiconductor chips  11 , it is necessary to provide as many wirings as the pads are necessary and to input appropriate input waveforms to the respective wirings. By way of example, in the second embodiment, one burn-in test wiring  22  is branched into a plurality of wirings according to the burn-in test input waveform generation circuits  24 .  
         [0042]     It is assumed, for example, that one burn-in test input waveform is fed to the burn-in test input waveform generation circuits  24  through the burn-in test terminal  21  and the burn-in test wiring  22 . Each burn-in test input waveform generation circuit  24  can branch this single input waveform to a plurality of wirings, output the branched waveforms to a plurality of terminals in the burn-in test input terminals  23 , and input them to the respective semiconductor chips  11 . It is also possible to output a plurality of types of waveforms to the wirings after they are branched.  
         [0043]     As can be seen, one burn-in test wiring  22 , for example, is branched into a plurality of wirings according to the burn-in test respective input waveform generation circuits  24 , and then the wirings are electrically connected to a plurality of pads, which the semiconductor chips  11  include, through the burn-in test waveform input terminals  23 , respectively. This can simplify the wiring structure of the burn-in test wiring  22 , as compared with the configuration in which a plurality of burn-in test wirings  22  are extended from the burn-in test terminal  21  and in which the wirings are electrically connected to the plurality of pads, which the semiconductor chips  11  include. In addition, if the burn-in test wiring  22  is simplified, it is possible to facilitate decreasing the number of the burn-in test terminals  21 .  
         [0044]     A burn-in test method conducted by using the burn-in test adapter in the second embodiment will be explained. A burn-in test input waveform from the burn-in test input waveform generator, not shown, is fed to the burn-in test wiring  22  through the burn-in test terminal  21 . This input waveform is fed to the burn-in test input waveform generation circuits  24  by this burn-in test wiring  22 . The burn-in test input waveform generation circuits  24  branch the input waveform into pieces according a desired number of wirings, convert the branched input waveforms into a plurality of types of waveforms, and input them into the respective semiconductor chips  11 .  
         [0045]     As can be seen, according to the second embodiment, by providing the burn-in test input waveform generation circuits  24 , it is possible to decrease the number of wirings provided in the burn-in test adapter  20   b  and the number of the burn-in test wirings  21 , thereby simplifying the structure of the burn-in test adapter  20   b  and facilitating the creation of the adapter  20   b.    
         [0046]     A third embodiment of the present invention is explained below with reference to  FIG. 4 . The third embodiment is such that a burn-in board that enables the execution of a burn-in test at one time, even if there are a plurality of burn-in test adapters, is further provided.  
         [0047]      FIG. 4  is a schematic diagram of the configuration of the burn-in test apparatus according to the present invention. Among the constituent elements of the burn-in test apparatus shown in  FIG. 4 , those equal in function to the burn-in test adapter  20   a  and the like in the first embodiment shown in  FIGS. 1 and 2  are denoted by the same reference symbols, respectively, and will not be repeatedly explained herein.  
         [0048]     The burn-in test apparatus in the third embodiment consists of the burn-in test adapter  20   a  to which the assembly substrate  10  can be attached, a the burn-in board  30 .  
         [0049]     The burn-in test adapter  20   a  is equal in configuration to that in the first embodiment. In  FIG. 4 , a state in which the assembly substrate  10  is attached to the burn-in test adapter  20   a  is shown. One to a plurality of such assembly substrates  10  are prepared. Each assembly substrate  10  and each burn-in test adapter  20   a  are fixed onto the burn-in board  30  by fixing units such as clippers using springs, for example, at positions at which the burn-in test wiring  22  is electrically connected to the burn-in test waveform input terminals  23 .  
         [0050]     The burn-in test terminal  21  on the burn-in test adapter  20   a  is arranged on a part of the outermost periphery of the burn-in test adapter  20   a  as shown in  FIG. 1  so as to facilitate the connection of the burn-in test adapter  20   a  to the burn-in board  30 . It is also possible to arrange a plurality of burn-in test terminals  21  on the burn-in test adapter  20   a.    
         [0051]     The burn-in board  30  is a board that feeds an input waveform from the burn-in test waveform generator, not shown, to the burn-in test adapter  20   a . A socket  31  on the burn-in board  30  electrically connects the burn-in test terminal  21  in the burn-in test adapter  20   a  to the burn-in board  30 , and fixes the burn-in test adapter  20   a  to the burn-in board  30 . A plurality of sockets  31  may be provided. In the latter case, a plurality of burn-in test adapters  20   a  can be attached onto the burn-in board  30 . The electrical connection of the burn-in adapter  20   a  to the burn-in board  30  is established by inserting the burn-in test terminal  21  in the burn-in test adapter  20   a  into the socket  31  on the burn-in board  30 . By so inserting, the burn-in test terminal  21  is electrically connected to the socket  31 .  
         [0052]     One to a plurality of burn-in test adapters  20   a  to which the assembly substrates  10  are attached, respectively, are provided. The burn-in test adapters  20   a  are connected to the burn-in board  30  three-dimensionally while the burn-in test adapters  20   a  are built vertically to the upper surface of the burn-in board  30 .  
         [0053]     Thus, the attachment of the burn-in test adapters  20   a  onto the burn-in board  30  can be made three-dimensionally using the burn-in test terminals  21  provided on the outermost peripheries of the burn-in test adapters  20   a  connected to the assembly substrates, respectively.  
         [0054]     A burn-in test method conducted by using the burn-in test apparatus in the third embodiment will next be explained. The semiconductor chips  11  are mounted on the assembly substrate  10  so as to be electrically connected thereto. The assembly substrate  10  on which the semiconductor chips  11  are mounted is electrically connected to the burn-in test adapter  20   a.    
         [0055]     In order to electrically connect the burn-in test adapter  20   a , on which the semiconductor chips  11  are mounted, to the burn-in board  30 , the burn-in test terminal  21  of the burn-in test adapter  20   a  is attached to the socket  31  on the burn-in board  30 .  
         [0056]     Thereafter, the burn-in board  30  is connected to the burn-in test input waveform generator, not shown, the semiconductor chips  11  are put in a high temperature environment, e.g., 125° C., and a burn-in test waveform is generated from the burn-in test input waveform generator. The burn-in test input waveform from the burn-in test input waveform generator is passed through wirings arranged on the burn-in board  30 , and input to the semiconductor chips  11  through the socket  31 , the burn-in test terminal  21 , the burn-in test wiring  22 , and the respective burn-in test input terminals  23 .  
         [0057]     The semiconductor chips  11  to which the burn-in test input waveform is thus input are kept in this state for a predetermined time, and then the assembly substrate  10  connected to the semiconductor chips  11  is detached from the burn-in test adapter  20   a . Finally, the assembly substrate  10  is cut into pieces so as to be separated according to the chips, the chips are determined whether they are good in a later test, and only the chips that are determined good are moved to the next step and packaged.  
         [0058]     In the third embodiment, the use of the burn-in test adapter  20   a  in the first embodiment has been explained. Alternatively, the burn-in test adapter  20   b  in the second embodiment may be used.  
         [0059]     As can be seen, according to the third embodiment, the burn-in test terminal  21  is provided on the outermost periphery of the burn-in test adapter  20   a , and the burn-in board  30  is provided in the burn-in test apparatus. Therefore, the burn-in test adapter  20   a  can be attached three-dimensionally, making it possible to increase the number of burn-in test measurement target chips to be tested at one time in a small space.  
         [0060]     Since it is unnecessary to detach the semiconductor chips  11  from the assembly substrate  10  after the burn-in test is executed, it is possible to decrease the number of operation steps.  
         [0061]     Further, since the semiconductor chips  11  can be subjected to the burn-in test before being packaged on the semiconductor integrated devices, it is possible to discriminate good semiconductor chips  11  from bad semiconductor chips  11  before packaging. It is thereby possible to package only the good chips without the need to package the bad chips, thus reducing the manufacturing cost of the semiconductor integrated devices.  
         [0062]     As explained so far, according to one aspect of the present invention, it is unnecessary to form the burn-in test wiring and the burn-in test terminal on the assembly substrate, and to cut off the burn-in test wiring on the burn-in test adapter. Therefore, it is possible to prevent the service life of the substrate cutting device used.to cut off the assembly substrate from being shortened. Besides, since it is possible to recycle the burn-in test adapter, it is advantageously possible to obtain the burn-in test apparatus that can conduct the test at low cost.  
         [0063]     Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.