Patent Publication Number: US-2007114204-A1

Title: Method for making guide panel for vertical probe card in batch

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a guide panel for use in a vertical probe card and more specifically, to a method for making the guide panel in batch.  
      2. Description of the Related Art  
      As shown in  FIG. 1 , a vertical probe card  1  for testing properties of an electronic component comprises multiple guide panels  2 , which have respectively a plurality of micro feed through holes  3  for the insertion of vertical probe pins  4  respectively to guide movement of the inserted vertical probe pins  4  along an axial direction of the through holes  3  and to prohibit the inserted vertical probe pins  4  from sideway displacement, thereby achieving probing the circuits of electronic component  5  under test.  
      Various guide panels for vertical probe cards have been disclosed. Exemplars are seen in U.S. Pat. Nos. 6,417,684; 6,297,657B1 and 6,404,211. According to U.S. Pat. No. 6,417,684, entitled “Securement of test points in a test head”, a conventional precision processing technique is employed to drill micro feed through holes in a ceramic, engineering plastic, glass or semiconductor material one by one. According to this conventional processing technique, there is a limitation on the position precision of micro feed through holes and the pitch between micro feed through holes (micro feed through hole position error will be greater than 15 μm; micro feed through hole pitch will be greater than 25 μm). Further, the manufacturing cost will be relatively increased subject to the number of the micro feed through holes to be made. This method does not meet modem technology requirements. According to U.S. Pat. No. 6,297,657B1, entitled “Temperature compensated vertical pin probing device”, metal plus dielectric material or insulating material are used for making the guide panel, and a laser processing technique is employed to make micro feed through holes on guide panels. This method achieves a better precision than the aforesaid conventional drilling method. However, using this laser processing technique to make the designed micro feed through holes one after another is complicated. The manufacturing cost and time are relatively increased subject to the number of the micro feed through holes to be made. According to U.S. Pat. No. 6,404,211, entitled “Metal buckling beam probe”, multiple metal layers are stacked to form the designed guide panel, and etching technology is employed to make micro feed through holes (apertures) in the metal layers. However, because etching technology cannot make micro feed through holes of high depth-to-diameter ratio, multiple metal layers must be stacked so that micro feed through holes of desired depth can be obtained. This fabrication method is complicated. Further, much time is wasted in stacking metal layers. Further, it is difficult to control levelling of stacked metal layers.  
     SUMMARY OF THE INVENTION  
      The present invention has been accomplished under the circumstances in view. It is the primary objective of the present invention to provide a guide panel fabrication method, which is able to make guide panels in batch, thereby saving much manufacturing time and lowering much manufacturing cost.  
      It is another objective of the present invention to provide a guide panel fabrication method, which makes micro feed through holes on guide panels in a high precision.  
      It is still another objective of the present invention to provide a guide panel fabrication method, which can greatly reduce the diameter of the micro feed through holes.  
      It is still another objective of the present invention to provide a guide panel fabrication method, which can greatly reduce the pitch between each two adjacent micro feed through holes.  
      It is still another object of the present invention to provide a guide panel fabrication method, which is practical to make big area guide panels for vertical probe card.  
      It is still another object of the present invention to provide a guide panel fabrication method, which is practical for making temperature compensated guide panels for vertical probe card.  
      To achieve these objectives of the present invention, the method for making guide panel for vertical probe card in batch comprises the steps of: a) preparing a non-metal substrate, b) depositing an etching masking layer on the substrate, c) forming a shielding layer having openings of a predetermined pattern on the etching masking layer, d) etching a part of the etching masking layer corresponding to the openings of the shielding layer by a reactive ion etching so as to form apertures on the etching masking layer corresponding to the openings of the shielding layer, e) removing the shielding layer, f) etching a part of the substrate corresponding to the apertures by an anisotropic etching so as to form micro feed through holes on the substrate corresponding to the apertures, and g) removing the etching masking layer so as to obtain the desired guide panel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic drawing showing a status of use of a conventional vertical probe card.  
       FIGS. 2A  to  2 J are schematic drawings showing the steps of manufacturing a guide panel according to a first preferred embodiment of the present invention.  
       FIGS. 3A  to  3 H are schematic drawings showing the steps of manufacturing a guide panel according to a second preferred embodiment of the present invention.  
       FIGS. 4A  to  4 I are schematic drawings showing the steps of manufacturing a guide panel according to a third preferred embodiment of the present invention.  
       FIGS. 5A  to  5 L are schematic drawings showing the steps of manufacturing a guide panel according to a fourth preferred embodiment of the present invention.  
       FIGS. 6A  to  6 K are schematic drawings showing the steps of manufacturing a guide panel according to a fifth preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIGS. 2A-2J  illustrate the steps for manufacturing a guide panel according to a first preferred embodiment of the present invention. This method is practical for making guide panels in batch at a time. The result guide panel has a plurality of micro feed through holes for the insertion of vertical probe pins respectively such that the movement of the inserted vertical probe pins will be limited to the axial direction of the micro feed through holes so as to prohibit the inserted vertical probe pins from sideway displacement. According to this embodiment, the guide panel fabrication method includes the following steps.  
      (A) As shown in  FIG. 2A , a thin substrate  11  made of a non-metal material, such as Si-based, GaN-based, GaAs-based and InP-based semiconductor materials, or any of other semiconductor materials suitable for anisotropic etching, is prepared. Glasses, ceramics or any of other nonconductive materials suitable for anisotropic etching can also be used for making the thin substrate  11 . Preferably, the thin substrate  11  is made of Si-based semiconductor material. The substrate  11  has a first side  111  and a second side  112  opposite to the first side  111 , as shown in  FIG. 2A .  
      (B) As shown in  FIG. 2B , a first etching masking layer  121  and a second etching masking layer  122  are respectively deposited on the first side  111  and second side  112  of the substrate  11  by low pressure chemical vapour deposition (LPCVD).  
      (C) As shown in  FIG. 2C , a shielding layer  13  having openings  131  with a predetermined pattern is formed on the first etching masking layer  121  by lithography technology. The shielding layer is usually known as a photo resist.  
      (D) As shown in  FIG. 2D , a part of the first etching masking layer  121  corresponding in location to the openings  131  of the shielding layer  13  is removed by the reactive ion etching (RIE) so as to form apertures  123  on the first etching masking layer  12  corresponding to the opening  131  of the shielding layer  13 .  
      (E) Remove the shielding layer  13 , as shown in  FIG. 2E .  
      (F) As shown in  FIG. 2F , a part of the substrate  11  corresponding in location to the apertures  123  is etched from the first side  111  toward the second side  112  until reaching the second etching masking layer  122  by an anisotropic wet etching so as to form micro feed through holes  113  in the substrate  11  corresponding to the apertures  123 . The etchant used for the anisotropic wet etching can be the one selected from the group consisting of KOH, ethylenediamine pyrocatechol (EDP), tetramethyl ammonium hydroxide (TMAH) and hydrazine.  
      (G) Remove the first etching masking layer  121  and the second etching masking layer  122  from the substrate  11  having the micro feed through holes  113 , and therefore the desired guide panel  10  is thus obtained, as shown in  FIG. 2G .  
      By means of the aforesaid manufacturing steps, the guide panels that have precision micro feed through holes spaced from one another at a small pitch can be made in batch at a time. Because the amount of the micro feed through holes does not complicate the manufacturing procedure (micro feed through holes are formed in the same step, i.e. Step F), the above-mentioned method provided by the present invention greatly reduces the manufacturing cost of guide panels and is practical for making guide panels having a large area. As indicted above, since the substrate is preferably made of silicon-based material, which is same as the electronic component under test, the guide panels made by the method of the present invention have the advantage of temperature compensative characteristic.  
      Further, when making relatively greater area guide panels, the following steps may be added so that prepared guide panels can be cut into small guide panels.  
      (H) As shown in  FIG. 2H , the guide panel  10  thus obtained from the step (G) is cut into multiple small guide panels subject to a predetermined size.  FIG. 2I  is a top view of the small guide panel.  
      (I) As shown in  FIG. 2J , the small guide panel  10  thus obtained from step (H) is bonded to a seat member  14 .  
      Further, an insulative material, such as SiO 2 , Al 2 O 3 , TiO 2 , or any suitable dielectric material, may be coated on the guide panel to enhance the insulative characteristic.  
      Further, a polymeric material, such as polyimide, may be coated on the guide panel to enhance the toughness of the guide panel or the lubricant characteristic of the micro feed through holes.  
       FIGS. 3A-3H  show a guide panel fabrication method according to a second preferred embodiment of the present invention. According to this embodiment, the guide panel fabrication method includes the following steps.  
      (A) As shown in  FIG. 3A , a thin substrate  21  of a non-metal material, for example a Si-based material in this embodiment, is prepared. The thin substrate  21  has a first side  211  and a second side  212  opposite to the first side  211 .  
      (B) As shown in  FIG. 3B , a shielding layer  22  is applied on the first side  211  of the substrate  21 .  
      (C) As shown in  FIG. 3C , a plurality of apertures  221  with a predetermined pattern are formed on the shielding layer  22  and reached to the first side  211  of the substrate  21  by the lithograph technology.  
      (D) As shown in  FIG. 3D , blind holes (blind vias)  213  of a predetermined depth are formed on the substrate  21  corresponding in location to the apertures  221  by an anisotropic dry etching selected from the group consisting of the inductively coupled plasma(ICP) etching, plasma etching, ion beam etching, deep reactive ion etching (DRIE) and focus ion beam etching.  
      (E) Grind the second side  212  of the substrate  21  by the back side thinning technique to open the blind holes  213 , thereby forming micro feed through holes  214  through the first side  211  and the second side  212 , as shown in  FIG. 3E .  
      (F) As shown in  FIG. 3F , the shielding layer  22  is removed; therefore, the desired guide panel  20  is thus obtained.  
      Similar to the aforesaid first embodiment, the guide panel thus obtained can be cut into small guide panels, i.e. the method further includes the following steps.  
      (G) As shown in  FIG. 3G ; the guide panel  20  thus obtained from step (F) is cut into small guide panels  20 .  
      (H) The guide panel  20  thus obtained is bonded to a seat member  23 , as shown in  FIG. 3H .  
      Further, an insulative material, such as SiO 2 , Al 2 O 3 , TiO 2 , or any suitable dielectric material may be coated on the guide panel to enhance the insulative characteristic.  
      Further, a polymeric material, such as polyimide, may be coated on the guide panel to enhance the toughness of the guide panel or the lubricant characteristic of the micro feed through holes.  
       FIGS. 4A-4I  show a guide panel fabrication method according to a third preferred embodiment of the present invention. According to this embodiment, the guide panel fabrication method includes the following steps.  
      (A) As shown in  FIG. 4A , a thin substrate  31  of non-metal material, for example a Si-based material in this embodiment, is prepared. The thin substrate  31  has a first side  311  and a second side  312  opposite to the first side  311 .  
      (B) As shown in  FIG. 4B , a first oxide layer  321  and a second oxide layer  322  are respectively deposited on the first side  311  and the second side  312  of the substrate  31  by the plasma enhanced chemical vapor deposition (PECVD). According to this embodiment, SiO 2  is used for depositing the first oxide layer and the second oxide layer.  
      (C) As shown in  FIG. 4C , a shielding layer  33  is applied on the first oxide layer  321 . According to this embodiment, the shielding layer  33  is a photo resist.  
      (D) As shown in  FIG. 4D , a plurality of openings  331  with a predetermined pattern are formed on the shielding layer  33  by the lithography technology.  
      (E) As shown in  FIG. 4E , a part of the first oxide layer  321  corresponding in location to the openings  331  is removed by the reactive ion etching so as to form a plurality of apertures  323  on the first oxide layer  321  corresponding to the openings  331 .  
      (F) As shown in  FIG. 4F , a part of the substrate  31  corresponding in location to the apertures  323  is etched from the first side  311  toward the second side  312  until reaching the second oxide layer  322  by the inductively coupled plasma etching so as to form micro feed through holes  313  on the substrate  31 .  
      (G) As shown in  FIG. 4G  the shielding layer  33  of  FIG. 4F  is removed.  
      (H) As shown in  FIG. 4H , the first oxide layer  321  and the second oxide layer  322  are removed, thereby obtaining the desired guide panel  30 .  
      If necessary, a further step (I) of cutting the guide panel  30  into small guide panels may be employed, as shown in  FIG. 4I .  
      Further, an insulative material, such as SiO 2 , Al 2 O 3 , TiO 2 , or any suitable dielectric material may be coated on the guide panel to enhance the insulative characteristic.  
      Furthermore, a polymeric material, such as polyimide, may be coated on the guide panel to enhance the toughness of the guide panel or the lubricant characteristic of the micro feed through holes.  
       FIGS. 5A-5L  show a guide panel fabrication method according to a fourth preferred embodiment of the present invention. According to this embodiment, the guide panel fabrication method includes the following steps.  
      (A) As shown in  FIG. 5A , a thin substrate  41  of non-metal material, for example a Si-based material in this embodiment, is prepared. The thin substrate  41  has a first side  411  and a second side  412  opposite to the first side  411 .  
      (B) As shown in  FIG. 5B , a first oxide layer  421  and a second oxide layer  422  are deposited on the first side  411  and the second side  412  of the substrate  41  respectively. According to this embodiment, SiO 2  is used for depositing the first oxide layer and the second oxide layer.  
      (C) As shown in  FIG. 5C , a first shielding layer  43  made of photo resist is formed on the first oxide layer  421 .  
      (D) As shown in  FIG. 5D , a plurality of openings  431  with a predetermined pattern are formed on the first shielding layer  43  and reached to the first oxide layer  421  by the lithography technology.  
      (E) As shown in  FIG. 5E , a part of the first oxide layer  421  corresponding in location to the openings  431  is removed by etching.  
      (F) As shown in  FIG. 5F , a part of the substrate  41  corresponding in location to the openings  431  is etched by the inductively coupled plasma etching or the anisotropic dry etching, such as plasma etching, ion beam etching, deep reactive ion etching (DRIE) and focus ion beam etching, so as to form a plurality of blind holes  46  on the substrate  41 , which have a depth and a diameter smaller than the depth and the diameter of the desired micro feed through holes to be made.  
      (G) As shown in  FIG. 5G , a nitride layer  44  is deposited on the top side of the first shielding layer  43  and the bottom side and peripheral wall of each of the openings  431  by the low pressure chemical vapor deposition.  
      (H) As shown in  FIG. 5H , a second shielding layer  45  is applied on the top side of the first shielding layer  43  and then a plurality of through holes  451  on the first shielding layer  43  corresponding in location to the opening  431  are formed by the lithograph technology.  
      (I) As shown in  FIG. 5I , a part of the nitride layer  44  located at the bottom of the openings  431  is removed by means of the reactive ion etching to let a part of the substrate  41  corresponding in location to the openings  431  be accessible from outside.  
      (J) Use the inductively coupled plasma etching technique to deepen the depth of the blind holes  46  on the substrate  41  until reaching the second oxide layer  422 , as shown in  FIG. 5J .  
      (K) As shown in  FIG. 5K , the first shielding layer  43  and the second shielding layer  45  are removed.  
      (L) As shown in  FIG. 5L , the first oxide layer  421 , the second oxide layer  422  and the nitride layer  44  are removed, thereby obtaining the desired guide panel  40  having micro feed through holes  47 .  
      Further, an insulative material, such as SiO 2 , Al 2 O 3 , TiO 2 , or any suitable dielectric material may be coated on the guide panel to enhance the insulative characteristic.  
      Furthermore, a polymeric material, for example polyimide, may be coated on the guide panel to enhance the toughness of the guide panel or the lubricant characteristic of the micro feed through holes.  
       FIGS. 6A-6K  illustrate a guide panel fabrication method according to a fifth preferred embodiment of the present invention. According to this embodiment, the guide panel fabrication method includes the following steps.  
      (A) Prepare a thin substrate  51  made of a non-metal material, for example a Si-based material in this embodiment, as shown in  FIG. 6A . The thin substrate  51  has a first side  511  and a second side  512  opposite to the first side  511 .  
      (B) Apply a first oxide layer  521  and a second oxide layer  522  on the first side  511  and the second side  512  of the substrate  51  respectively, and then deposit a first nitride layer  531  and a second nitride layer  532  on the first oxide layer  521  and the second oxide layer  522  respectively by the low pressure chemical vapor deposition, as shown in  FIG. 6B .  
      (C) Apply a first shielding layer  53  on the second oxide layer  532 , and then form an opening  541  with a predetermined area on the first shielding layer  54  by the lithograph technology, and then remove a part of the second nitride layer  532  corresponding to the opening  541  and a part of the second oxide layer  522  corresponding to the opening  541  by the reactive ion etching technique so as to let a part of the substrate  51  corresponding to the opening  541  be accessible from outside, as shown in  FIG. 6C .  
      (D) Use KOH or any of a variety of other etchant for anisotropic wet etching to etch the part of the substrate  51  corresponding to the opening  541  subject to a predetermined depth and diameter so as to form a recessed portion  513  on the second side  512  of the substrate  51 , and then remove the first shielding layer  54  and the first and second nitride layers  531  and  532 , as shown in  FIG. 6D .  
      (E) As shown in  FIG. 6E , a part of the first oxide layer  521  is etched by the reactive ion etching so as to make a plurality of first apertures  523  of a predetermined pattern and two second apertures  524  on the first oxide layer  521  such that the part of the first side  511  of the substrate  51  corresponding to the first and second apertures  523  and  524  is accessible from outside. The second apertures  524  have a relatively greater diameter than that of the first apertures  523 . In addition, the second apertures  524  are located at two opposite lateral sides of the first oxide layer  521 .  
      (F) As shown in  FIG. 6F , a second shielding layer  55  is applied on the first oxide layer  521  and then a plurality of through holes  551  are formed on the second shielding layer  55  in communication with the first and second apertures  523  and  524 , and then a third shielding layer  56  of a predetermined thickness is deposited on the peripheral wall of each second aperture  524  without blocking the passage between the first side  512  of the substrate  51  and the second apertures  524 .  
      (G) As shown in  FIG. 6G , use the inductively coupled plasma etching or the anisotropic dry etching, such as plasma etching, ion beam etching, deep reactive ion etching and focus ion beam etching, to make a plurality blind holes  57  of predetermined depth and diameter on the substrate  51  corresponding to the first and second apertures  523  and  524 .  
      (H) As shown in  FIG. 6H , the second shielding layer  55  and the third shielding layer  56  are removed.  
      (I) Use the inductively coupled plasma etching or the anisotropic dry etching to deepen the depth of the blind holes  57 , thereby forming the designed micro feed through holes  58  on the substrate  51  corresponding to the first and second apertures  523  and  524 .  
      (J) As shown in  FIG. 6J , the first oxide layer  521  and the second oxide layer  522  are removed, thereby obtaining the desired guide panel  50 . As shown in  FIG. 6J , the guide panel  50  has a bottom portion acting as the seat member  14  of  FIG. 2J . In other words, by means of this method of the fifth embodiment the substrate  11  and the seat member  14  of  FIG. 2J  can be integrally formed.  
       FIG. 6K  is a top view of  FIG. 6J . As shown in  FIG. 6K , the two relatively greater through holes at two opposite lateral sides of the guide panel  50  are providing for mounting on an external object.  
      According to the aforesaid five embodiments, the present invention provides a guide panel fabrication method, which uses the anisotropic etching technique to make micro feed through holes on a substrate so that the guide panels for vertical probe card can be made in batch at a time to save the manufacturing time and to reduce the manufacturing cost. Further, the method of the present invention greatly improves the precision of the micro feed through holes, greatly reduces the pitch between each two adjacent micro feed through holes, and is suitable in making guide panels having relatively large area for vertical probe card. Furthermore, the invention is also practical for making temperature compensated guide panels for vertical probe card.