Patent Publication Number: US-2010109697-A1

Title: Probe card, needles of probe card, and method of manufacturing the needles of probe card

Description:
TECHNICAL FIELD  
     The present invention relates to a test apparatus for semiconductor devices. More particularly, this invention relates to needles of a probe card and a method of the needles, which makes the needles of a probe card precisely touch pads of a wafer die and prevents the needles from twisting, thereby allowing electrical signals to be smoothly transmitted. 
     BACKGROUND ART  
     In general, semiconductor devices are manufactured through a fabrication process where a pattern is formed on a wafer and through an assembly process where each semiconductor device is assembled from the patterned wafer. 
     Between the fabrication process and the assembly process, the semiconductor devices fabricated on the wafer each undergo an electrical die sorting (EDS) process for testing electrical features. 
     Here, the EDS process refers to a process to determine whether the semiconductor devices fabricated on the wafer fail. The EDS process tests semiconductor devices using a test apparatus that applies an electrical signal to the semiconductor devices on the wafer and analyzes a response electrical signal from the devices. 
     In order to transmit the electrical signals between the test apparatus and pads of the semiconductor devices, a probe card is used. The probe card is configured to include one or more needles that contact the pads connected to the semiconductor devices of the wafer. The test apparatus for testing semiconductor devices transmits/receives electrical signals to/from the pads through the needles of the probe card, thereby determining whether the semiconductor devices fail. 
     Recently, the semiconductor devices have become highly integrated and tiny, design rules of a pattern have also become more minute. As semiconductor devices are becoming smaller, the size of the pads of a wafer die, to which needles of a probe card are touched, are also becoming smaller. As the size of the pads of a wafer die becomes more minute, a problem occurs, which is that plated needles of a probe card do not correctly touched the pads. Such problems will be described in detail later. 
       FIG. 1  is a cross-sectional view depicting a conventional needle of a probe card. 
     The convention needle  100  of a probe card is formed to include a probing portion  110  and a beam portion  120 , which are plated to form a plated portion  121 . That is, the needle  100  undergoes a plating process such that the plated portion  121  can prevent it from deforming, bending or twisting and so forth. As a result of the plating process, the probing portion  110  of the needle  100  becomes blunt. But, since the size of the pads of a wafer has become minute as described above, the contact area between the blunt probing portion  110  and the pads (not shown) is relatively increased, which make the contact therebetween become imprecise. 
     Meanwhile, in order for the needle  100  to firmly contact the pad of a wafer die, the needle  100  undergoes pin pressure (which refers to the force applied to per unit area of pads by the ends of the needles). As semiconductor devices are increasingly highly integrated, the number of pads also increases, thereby requiring an increased number of needles  100 . With the number of needles  100  increased, this increase in needles also increases the pressing force distributed to the respective needles  100 . In order to maintain constant pin pressure, a force applied to the probe card with the needles must be increased. 
     However, since the conventional needle  100  with the plated portion  121  has a relatively large contact area of its probing portion  110 , it must undergo a force, increased corresponding to the increased contact area, to keep a certain pin pressure constant. In that case, as the semiconductor devices are becoming highly integrated and minute, the number of needles  100  must be increased. As the number of the needles  100  is increased, a force applied to the probe card must be increased to maintain a certain pin pressure per needle. However, when the force applied to the needle  100  is increased, the test apparatus for testing semiconductor devices causes many problems. 
     DISCLOSURE OF INVENTION  
     Technical Problem 
     Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a needle of a probe card and its manufacturing method that can maintain the straightness of a beam portion of the needle, which is plated, reduce the contact area between a probing portion and a pad of a wafer die, and prevent the test apparatus from malfunctioning. 
     It is another object of the present invention to provide a probe card that can prevent its needles from mutually interfering and smoothly test highly integrated semiconductor devices. 
     Technical Solution 
     In accordance with a first aspect of the present invention, there is provided a needle of a probe card, which includes: a probing portion for contacting a pad of a wafer die at a certain pin pressure; a soldered portion soldered to a circuit board of the probe card, for transmitting an electrical signal to the probing portion; and a beam portion integrally connecting the probing portion and the soldered portion and having elasticity to exhibit a certain pin pressure by which the probing portion  210  can elastically contact the pad of a wafer die. Preferably, the beam portion undergoes a plating process. 
     In accordance with a second aspect of the present invention, there is provided a needle of a probe card, which includes: a probing portion for contacting a pad of a wafer die at a certain pin pressure; a soldered portion soldered to a circuit board of the probe card, for transmitting an electrical signal to the probing portion; and a beam portion integrally connecting the probing portion and the soldered portion and having elasticity to exhibit a certain pin pressure by which the probing portion  210  can elastically contact the pad of a wafer die. Preferably, the soldered portion and the beam portion undergo a plating process. 
     In accordance with a third aspect of the present invention, there is provided a method of manufacturing a needle of a probe card, which includes: coating a probing portion of a raw body of the needle with a photoresist to fabricate a first intermediate body; plating the first intermediate body to fabricating a second intermediate body; and removing the photoresist from the probing portion of the second intermediate body. 
     In accordance with a fourth aspect of the present invention, there is provided a method of manufacturing a needle of a probe card, which includes: coating a raw body of the needle with a photoresist to fabricate a first intermediate body; removing the photoresist from a beam portion and a probing portion of the first intermediate body of the needle to fabricate a second intermediate body; coating the probing portion of the second intermediate body of the needle with the photoresist to fabricate a third intermediate body; plating the third intermediate body of the body to fabricate a fourth intermediate body; and removing the photoresist from the fourth intermediate body of the needle. 
     *In accordance with a fifth aspect of the present invention, there is provided a method of manufacturing a needle of a probe card, which includes: coating a raw body of the needle with a photoresist to fabricate a first intermediate body of the needle; removing the photoresist from a beam portion and a soldered portion of the first intermediate body to fabricate a second intermediate body of the needle; coating the soldered portion of the second intermediate body with the photoresist to fabricate a third intermediate body of the needle; plating the third intermediate body to fabricate a fourth intermediate body of the needle; and removing the photoresist from the fourth intermediate body of the needle. 
     In accordance with a sixth aspect of the present invention, there is provided a probe card including: a substrate having a plurality of circuit patterns; and a plurality of needles electrically connected to the plurality of circuit patterns. 
     Each needle includes: a probing portion contacting a pad of a wafer die at a certain pin pressure; a soldered portion soldered to the substrate, for transmitting an electrical signal to the probing portion; and a beam portion integrally connecting the probing portion and the soldered portion and having an electricity to exhibit a certain pin pressure by which the probing portion  210  can elastically contact the pad of a wafer die. Here, the adjacent needles are aligned in such way that their distances between the soldered portion and the beam portion are located at different positions. 
     Preferably, the beam portions of the plurality of needles undergo a plating process. 
     Preferably, the beam portion of the needle and the adjacent beam portion of the adjacent needle are located at different positions, in which a top position of the beam portion and a bottom position of the adjacent beam portion are spaced apart a certain value. 
     Advantageous Effects 
     As described above, the method of manufacturing a needle of a probe card has advantages in that: since the beam portion of the needle for a probe card undergoes a plating process, the needle can be prevented from twisting; since the contact area between the probing portion and the pad of a wafer die is relatively small, the needle can precisely contact the pad; with a relatively small elastic force of the beam portion, the needle can maintain a certain level of pin pressure to contact the pad without overworking a test apparatus; and since the soldered portion of the needle does not undergo a plating process, the needle can be easily replaced. 
     Also, the needle of the probe card according to the present invention can enhance precision contacting of the pad of a wafer die, can precisely contact the pad of a wafer die consistently, can be easily replaced with another one, and does not overwork a test apparatus. 
     In addition, since the probe card of the present invention can be configured by combining different types of needles whose intervals between the beam portion and soldered portion are different from each, it does not cause interference therebetween the needles and can be highly integrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       The above and other objects, features, and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a cross-sectional view depicting a conventional needle of a probe card; 
         FIG. 2  is a cross-sectional view depicting a needle of a probe card according to the present invention; 
         FIGS. 3 to 6  are views illustrating a first embodiment of a method of manufacturing a needle of a probe card according to the present invention; 
         FIGS. 7 to 12  are views illustrating a second embodiment of a method of manufacturing a needle of a probe card according to the present invention; 
         FIGS. 13 to 18  are views illustrating a third embodiment of a method of manufacturing a needle of a probe card according to the present invention; 
         FIG. 19  is a front view depicting needles whose beam portions has undergone a plating process, which are soldered on a substrate of a probe card; and 
         FIGS. 20 and 21  are side cross-sectional view and front cross-sectional views depicting a part of needles included in a probe card, according to an embodiment of the present invention. 
     
    
    
     BRIEF DESCRIPTION OF SYMBOLS IN THE DRAWINGS  
       200 : needle 
       210 : probing portion 
       220 : beam portion 
       221 : plating 
       230 : soldered portion 
     BEST MODE FOR CARRYING OUT THE INVENTION  
     Preferred embodiments according to a needle of a probe card, a probe card, and its manufacturing method of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 2  is a cross-sectional view depicting a needle of a probe card according to the present invention. 
     The needle  200  of a probe card is configured to include: a probing portion  210  contacting a pad of a wafer die, not shown; a soldered portion  230  soldered to a circuit board (not shown) of the probe card, for transmitting an electrical signal to the probing portion  210 ; and a beam portion  220  integrally connecting the probing portion  210  and the soldered portion  230  and having elasticity to exhibit a certain pin pressure by which the probing portion  210  can elastically contact the pad of a wafer die. Here, the beam undergoes a plating process to form a plated portion  221  that prevents the probing portion  210  from twisting. 
     The probing portion  210  is integrally connected to the beam portion  220  and is fabricated to have a pointed end (hereinafter referred to as a tip). The probing portion  210  touches the pad of a wafer die at certain pin pressure. The probing portion  210  does not undergo a plating process, so that its tip is not blunt. Therefore, the area contacting the probing portion  210  and the pad of a wafer remains relatively small. 
     The soldered portion  230  is soldered with a circuit board of the probe card such that the needle can be attached to the circuit board, thereby allowing electrical signals to transmit between the probe card and the pads of a wafer die. It is preferable that the soldered portion  230  of the needle  200  does not undergo a plating process so that the needle  200  can be easily replaced. 
     The beam portion  220  is located between the probing portion  210  and the soldered portion  230  and integrally connects the same to support the probing portion  210 . Here, the beam portion  220  enables the probing portion  210  to contact the pad of a wafer die at a certain pin pressure caused by its elasticity (i.e., a shape-restoring force). The beam portion  220  undergoes a plating process to form a plated portion  221  that prevents the needle  200  from twisting. The beam portion  220  is plated with preferable conductive metal materials, such as Au, Ni, and Cu, etc, thereby forming a plated portion  221 . 
     As such, since the needle  200  is formed in such a way that its probing portion  210  is not blunt, the contact area of the pad by the probing portion  210  is relatively small. Therefore, event if the beam portion  220  exhibits a relatively small amount of elastic force, the probing potion  210  can contact the pad at a certain level of pin pressure, keeping the test apparatus from malfunctioning. As well, since the beam portion  220  forms a plated portion  221 , the needle  200  cannot twist. Consequently, the needle  200  of a probe card can precisely contact the pad of a wafer die consistently, and will not overwork the test apparatus. 
     The following is a description of embodiments of a method of manufacturing a needle of a probe according to the present invention. 
       FIGS. 3 to 6  are views illustrating a first embodiment of a method of manufacturing a needle of a probe card according to the present invention. 
     Firstly, as shown in  FIG. 3 , a tip portion  310  of a raw body  300   a  of a needle for a probe card is coated with a photo resist PR 1 . Similar to the conventional needle of a probe card, the raw body  300   a  may be preferably made of Ni—W, etc. The photoresist PR 1  is implemented by THB-151N (JSR), PMER, AZ9296, etc. After completing the coating of photo resist PR 1 , a first intermediate body  300   b  of the needle is fabricated as shown in  FIG. 4 . 
     Next, as shown in  FIG. 5 , the first intermediate body  300   b  undergoes a plating process to form a plated portion  321 . The plated portion  321 , as described above, may be formed by a conductive material, such as Au, Ni, and Cu, etc. The photoresist PR 1  coated on the first intermediate body  300   b  serves as a mask that prevents the probing potion  310  from being plated. Consequently, as the first intermediate body  300   b  of the needle forms the plated portion  321 , a second intermediate body  300   c  is fabricated. 
     Finally, as shown in  FIG. 6 , the photoresist PR 1  is removed from the probing portion  310  of the second intermediate body  300   c  of the needle using a photoresist remover. The photoresist remover is implemented by THB-S1, PMER 104, and AZ700k, etc. Since the photoresist PR 1  coating the probing portion  310  serves as a mask, the plated portion  310  does not undergo the plating process. Therefore, the needle  300  of a probe card, only whose beam portion  320  has undergone the plating process, is fabricated as shown in  FIG. 6 . 
       FIGS. 7 to 12  are views illustrating a second embodiment of a method of manufacturing a needle of a probe card according to the present invention. 
     Firstly, as shown in  FIG. 7 , a raw body  400   a  of a needle for a probe card is coated with a photoresist PR 2 , thereby fabricating a first intermediate body  400   b  as shown in  FIG. 8 . Here, the photoresist PR 2  may be implemented by employing the same as in first embodiment. The first intermediate body  400   b  is fabricated in such a way the raw body  400   a  is entirely coated with the photoresist PR 2 . 
     Next, as shown in  FIG. 9 , the photoresist PR 2  is removed from the beam portion  420  and probing portion  410  of the first intermediate body  400   b,  thereby fabricating a second intermediate body  400   c.  Here, the remover of the photoresist PR 2  may be implemented by employing the same as the first embodiment. As a result, the second intermediate body  400   c  is formed in such a way that only the soldered portion  430  is coated with the photoresist PR 2 . 
     After that, the probing portion  410  of the second intermediate body  400   c  is coated with the photoresist PR 2 , thereby fabricating a third intermediate body  400   d  as shown in  FIG. 10 . That is, the third intermediate body  400   d  is formed in such a way that the soldered portion  430  and probing portion  410  are coated with the photoresist PR 2 . 
     Subsequently, the third intermediate body  400   d  undergoes a plating process to form a plated portion  421 , thereby fabricating a fourth intermediate body  400   e  as shown in  FIG. 11 . That is, the fourth intermediate body  400   e  is fabricated in such a way that only a beam portion  420  undergoes the plating process to form the plated portion  421 , because the photoresist PR 2  is not on the beam portion  420  of the third intermediate body  400   d.    
     Finally, the photoresist PR 2  is removed from the soldered portion  430  and probing portion  410  of the fourth intermediate body  400   e  using the remover of the photoresist PR 2 . As a result, the needle  400  of a probe card, whose beam portion  420  only has undergone the plating process, is fabricated as shown in  FIG. 12 . 
       FIGS. 13 to 18  are views illustrating a third embodiment of a method of manufacturing a needle of a probe card according to the present invention. 
     Firstly, as shown in  FIG. 13 , a raw body  500   a  of a needle for a probe card is coated with a photoresist PR 3 , thereby fabricating a first intermediate body  500   b  as shown in  FIG. 14 . Here, the photoresist PR 3  may be implemented by employing the same as in the former embodiments. The first intermediate body  500   b  is fabricated in such a way the raw body  500   a  is entirely coated by the photoresist PR 3 . 
     Next, as shown in  FIG. 15 , the photoresist PR 3  is removed from the beam portion  520  and soldered portion  530  of the first intermediate body  500   b,  thereby fabricating a second intermediate body  500   c.  Here, the remover of the photoresist PR 3  may be implemented by employing the same as the former embodiments. As a result, the second intermediate body  500   c  is formed in such a way that the photoresist PR 3  remains only on the probing portion  510 . 
     After that, a soldered portion  530  of the second intermediate body  500   c  is coated with the photoresist PR 3 , thereby fabricating a third intermediate body  500   d  as shown in  FIG. 16 . That is, the third intermediate body  500   d  is formed in such a way that the soldered portion  530  and probing portion  510  are coated with the photoresist PR 3 . 
     Subsequently, the third intermediate body  500   d  undergoes a plating process to form a plated portion  521 , thereby fabricating a fourth intermediate body  500   e  as shown in  FIG. 17 . That is, the fourth intermediate body  500   e  is fabricated in such a way that only a beam portion  520  undergoes the plating process to form the plated portion  521 , because the photoresist PR 3  does not exist in the beam portion  520  of the third intermediate body  500   d.    
     Finally, the photoresist PR 3  is removed from the soldered portion  530  and probing portion  410  of the fourth intermediate body  500   c  using the remover of the photoresist PR 3 . As a result, the needle  500  of a probe cared, whose beam portion  520  only has undergone the plating process, is fabricated as shown in  FIG. 18 . 
     The following is a description of a probe card according to the present invention. 
       FIG. 19  is a front view depicting needles whose beam portions has undergone a plating process, which are soldered on a substrate of a probe card. 
     The probe card is configured to include a substrate  700 , on which a plurality of circuit patterns are formed, and a plurality of needles  600  soldered to the substrate  700 . Each needle  600  is classified into a soldered portion  630  to be soldered to the substrate  700 , a beam portion  621  having undergone a plating process to form a plated portion  621 , a probing portion  621  of a distance b, and a portion of a height a between the soldered portion and the beam portion  620 . Here, all the needles  600  are fabricated in such a way that they have the same height a and have the same height b. As well, the needles are aligned in such a way that their beam portions are very close to each other at an interval d. When the interval d between the beam portions  620  is relatively small, this can cause the needles to mutually interfere with each other. 
       FIGS. 20 and 21  are side cross-sectional view and front cross-sectional view depicting a part of needles included in a probe card, according to an embodiment of the present invention. 
     The probe card is configured to include a needle  600   a  and a needle  600   b  adjacent to the needle  600   a  (hereinafter referred to as adjacent needle  600   b ), whose beam portions  620   a  and  620   b  are formed at respective positions that are different from each other in height. 
     Specifically, the probe card aligns the needles  600   a  and  600   b  in such a way that the height c from the soldered portion  630   a  to the beam portion  620   a  of the needle  600   a  is different from the height c′ from the soldered portion  630   b  to the beam portion  620   b  of the adjacent needle  600   b  or the distances b of the probing portion  610   a  of the needle  600   a  is different from the distance b′ of the proving portion  610   b  of the needle  600   b.  That is, the beam portions  620   a  and  620   b  are different from each other in their positions occupied in the needles  600   a  and  600   b,  respectively. 
     As is well shown,  FIGS. 20 and 21  depict the difference t of the positions (or heights) between the beam portions  620   a  and  620   b  of the needle  600   a  and the adjacent needle  600   b.    
     Since there is the difference t between the positions (heights) of the beam portions  620   a  and  620   b,  the probe card accordingly has the following advantages: 
     The plated portions  621   a  and  621   b  formed on the respective beam portions  620   a  and  620   b  do not interfere with each other. 
     As well, the needles  600   a  and  600   b  can be highly integrated on the substrate  700 , thereby manufacturing a highly needle-integrated probe card. 
     The probe card according to the present invention may be implemented by two or more types of needles whose beam portion positions are different from each other. 
     That is, the probe card according to the present invention can be highly integrated by combining various types of needles, thereby conveniently and efficiently testing highly integrated semiconductor devices. 
     Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 
     INDUSTRIAL APPLICABILITY  
     The present invention can be widely applied to the test systems for testing semiconductor devices.