DE19853445A1 - Contact pins, for semiconductor chip test cards, are produced by electroforming pin tips and adjoining spring stirrups using structured resist layers - Google Patents

Abstract

Contact pin production comprises electroforming pin tips (7) and adjoining spring stirrups (11) using structured resist layers (3, 8). Simultaneous production of contact pins with a pin tip (7) and spring stirrup (11) comprises electroforming the pin tips in the structures of a resist material layer (3), electroforming the adjoining spring stirrups in the structures of a further overlying resist layer (8) and removing the resist material. Independent claims are also included for the following: (i) production of a mould for contact pins by using a contact pin structure, produced as described above, for producing a polymeric mold; (ii) a contact pin, produced by the above process, for making electrical contact to semiconductor circuits; and (iii) an IC test card having contact pins as described above or produced by the above process. Preferred Features: The contact pins are made of copper, nickel or tungsten boride.

Description

The present invention relates to contact needles for inte circuits and processes for their manufacture. Ins In particular, the invention relates to contact needles for test cards for electrical testing of integrated circuits in their Manufacturing.

Integrated circuits have so-called contact areas provided to which the power supply to the circuit is placed and the signal input and output from the Circuits. These contact areas must be connected with the outside world when a circuit to be used in an electronic circuit.

When installing the integrated circuits in their housings the contact areas are mostly with appropriate contact ten in the housings via thin wires and solder joints the. However, it is also possible to solder-free the contact surfaces about needles pressed into them with the contacts in the respective to connect to the housing.

After manufacturing integrated circuits, these need to be be checked for proper functioning. There this happens before the integrated circuits get into the Housing be installed, namely on the complete Wafer with a plurality of circuits thereon the signals necessary for testing must be direct can be tapped from the contact surfaces. For this, be like this called probe card devices used as part of egg tester the electrical contact with the contact surfaces manufacture the integrated circuits. The test car tenvorrichtung consists of a holder for test cards, the a mechanical and electrical connection between test car  and test equipment. The actual test card includes resilient contacts with corresponding contacts on the Holders are connected. The resilient contacts are yours Number and arrangement forth to the contact areas of a certain Adapted type of integrated circuit. To the testing various integrated circuits in a simple manner to allow and the wear of the electrical contacts the test cards are to be taken into account exchangeable.

When testing the integrated circuits, a so-called. Prober a processed wafer spatially for testing card device that the resilient contacts in electrical Connection with the respective contact surfaces of one or more Integrated circuits located on the wafer come. The test device can then check the proper function on the contacted integrated circuits. After completing the test, the contacts are released and the Prober positions the wafer so that additional circuits can be checked. If all integrated circuits are checked on a wafer in this way, the wafer removed from the tester and the fixes as functional circuits are separated and further processed tet.

The following is the state of the art and the present Invention primarily with reference to the use of the inventions described contact pins for such test cards. However, it is understood that the contact needles are not on egg such use should be limited and also other uses for making solderless contacts should be included.

Test cards are usually used in the prior art det where the resilient contacts are designed as needles  are. These test cards are called needle cards. The Needles are made of wires that are made of tungsten steel or a copper-beryllium alloy.

When the contact surfaces contact, the needles are ge Aimed into the surface of the contact and laterally postponed, a process known as "scrubbing" is drawn and which is used on the contact surfaces break up existing oxide surface layers and thereby to enable a lower contact resistance. To the to check the penetration depth that occurs and a Destruction of the integrated circuits to be tested ver prevent needles with defined spring properties used.

The manufacture of these prior art needle cards is very expensive. The high demands on precision the contact needles with regard to their lateral alignment of approx. 20 µm and the planarity of the needle tips with regard to Their contact level of 25 µm currently does not allow au automated assembly of the needle cards. The more complex ones Circuits and needle cards for simultaneous measurement several circuits required several hundred needles which is therefore inserted into the needle cards by hand and for the integrated circuit to be tested individually with respect to Contact areas aligned.

This previous handiwork represents a further increase in Simultaneous measurement options, e.g. B. from 8 to 16 or 32 the same Circuits that can be tested at an early stage or an increase in comm complexity of the circuits to be tested due to the need agile multiplication of the number of needles per needle card gene, since the manufacturing effort increases disproportionately.  

Due to the mechanical load on the needle tips when entering the contact area and scrubbing un The test cards are subject to wear and tear that will affect their life limited time. Test cards are therefore wear parts that should advantageously be inexpensive to manufacture.

Various approaches have been taken in the prior art the manufacturing costs through simplified manufacturability to improve.

In the case of a proposal from UPSYS, Corbeil Essone, Frank rich, pins are used instead of needles, which are used in a Plate are vertically slidably mounted. These pens are hung swinging over wires, with the top end the pins are anchored in a second plate. During the test process the pins with a defined force on the Contact surfaces of the integrated circuit pressed. Next a complicated structure and still complex Manufacturing this approach has the disadvantage that the Integra density due to the hole spacing to be observed if restricted. In addition, the pens tend to to clamp at high measurement requirements.

In another process that Feinmetall, Herren berg, Germany, suggested wires are inserted sets that led through passages in a silicon substrate become. These guide structures are in the silicon carrier etched. During testing, the wires are in contact with the Brought contact areas by placing the silicon substrate in parallel is approached to the integrated circuit. The The disadvantage of this method is that the packing density is caused by the Leadership structures are limited. The wires at the Monta ge carefully introduced and used to check the upright forces acting on the silicon surface of the wafer points must be provided under the management structures.  

In addition, the method has the further disadvantage that a exact control and guidance of the lateral movement of the wires te in the passages due to the necessary tolerances is difficult.

In a further method in the prior art, the Established contacts via the tips of so-called bumbs, ke gel-like protrusions on a surface. The bumbs who in the desired arrangement together with their carrier made microtechnically. The carrier is on a membrane arranged in a version in the form of a normal test card is held and thus as an exchange for conventional Pin cards can serve. The membrane creates the necessary Contact pressure between the bumbs and the Contact areas of the integrated circuits. This approach has the disadvantage that careful control of the circulation forces on the contact surfaces difficult and a scrubbing of the Contact areas is not possible. This creates un wished high contact resistance.

It is therefore the object of the present invention, Kon tactile needles and a manufacturing process for it which is a simple, cheap manufacture of high precision enable and nevertheless the desirable cleaning (scrubbing) the contact areas before carrying out a test or contacting integrated circuits in components allow.

According to the invention, this object is achieved by the method according to independent claims 1, and 15, Kontaktna deln according to the independent claim 16, a test card according to independent claim 19 and usage form men according to independent claims 22 and 23. Others advantageous configurations, details and aspects of the invention dung result from the dependent claims, the  Description and the attached drawing. The patent claims che see themselves as a first, non-binding attempt to describe the invention in general terms.

The invention is directed to a method for the simultaneous manufacture of at least one contact needle with a needle tip and spring clip, which is characterized by the following steps:

• A) Galvanic formation of the needle tips in the structures a layer of resist material;
• B) Galvanic formation of the one attached to the needle tip Spring clip in the structures of at least one other Re sist layer arranged on the first resist layer; and
• C) Remove the resist material.

Step A preferably comprises the substeps

• 1. Coating a substrate with the first layer Resist material;
• 2. Forming negative shapes for the needle tips in the Resist material; and
• 3. Galvanic filling of the negative forms with at least a first contact needle material.

This method can be designed so that the galvanic Refill with at least two contact needle materials in a row he follows.

Step B of the method according to the invention can include the following substeps:

• 1. Application of a further layer of resist material;
• 2. Forming negative molds for at least the spring clips the contact needles in the further layer of resist material, so that the spring clip is adjusted in the arrangement of the needle tips become; and  
• 3. Galvanic filling of the negative forms with a two contact needle material.

The shaping of the negative forms preferably includes the following steps:

• a) irradiation of the resist material through a mask
• b) Developing the resist material to remove irradiated ones Areas.

Finally, the process described above can be followed by the further step

• C) Coating the needle tip and / or the spring clip with another contact needle material connect.

A plurality of contact needles can be arranged so that they correspond to the arrangement of contact areas of an integrated circuit. It is possible that the sub-steps B1-B3 are carried out at least one more time in order to obtain a multi-storey structure of the contact needles with the same reference surface for the needle tips. In a further aspect, the invention is directed to a method for producing a mold for contact needles, which is characterized by the following steps:

• 1. Making a contact needle assembly by means of the above be written procedures,
• 2. Make a polymer mold according to this contact needle arrangement nung.

In further aspects, the invention relates to namely galvanically deposited contact needles, so as on test cards, which the Kontaktna invention include. Finally, the invention is based on the Ver use of the contact needles in test cards and for contacting directed by integrated circuits.  

In the following the invention will be described with reference to Fig. 1, which shows the inventive method of manufacturing contact needles.

The present invention combines the manufacture and the Use of contact needles with their microtechnical manufacturer lung. According to the invention, the contact needles are made by several Microstructuring steps followed by galvanofor mung manufactured.

The microstructuring can be carried out using known methods If these are suitable, structures in the desired to produce the largest size, and a galvanic filling allow elaborated structures, e.g. B. the thick film Photolithography, the normal photolithography, and the LIGA technology. The preferred LIGA technique, such as by Menz & Bley, "Microsystem Technology for Engineers", VCH-Verlag, Weinheim, has been described as one of the most promising and flexible procedures for mas production of three-dimensional microstructures. she allows structures up to 1 mm thick with an accuracy speed, which is 0.2 µm at a thickness of 500 µm.

In general, a wafer 2 , e.g. B. of silicon or titanium, be coated with a resist material in the desired thickness, z. B. by a spin coating process (centrifugation). As a resist material, the known materials come into question, such as. B. Polymethyl methacrylate. This leads to the formation of a resist layer. Depending on the technology used, it may be necessary or advantageous to apply the rice layer in several steps to the substrate, so that there is a multilayer structure of the layer. The back of the wafer can be coated for passivation, z. B. with silicon carbide.

The resist layer is now irradiated through a mask. The use of synchrotron radiation is preferred here, since its low divergence and short wavelength allow the formation of extremely steep side walls of the structures in the rice layer 3 (see arrows 6 in (1) and (3) of FIG. 1). The irradiated windows are now removed, which z. B. can be done with a conventional developer.

The resulting negative forms can now galvanically be filled.

According to the invention, in a first main embodiment, the contact needles are produced in a process which includes at least two of the above processes, the needle tip 7 first being galvanically formed in a first stage, and in at least one further stage the rest of the needle body, the so-called Spring clip 11 , placed at a predetermined angle on the needle tip 7 , is formed galvanically.

The method for forming the needle tip preferably comprises a number of sub-steps, in which the substrate, for. B. a titanium wafer, is coated with a resist material 3 , then in the resist material 3, the structures or Ne gativformen 4 are made, which are then galvanically filled with at least a first contact needle material to form the needle tips 7 . It is also possible to re, z. B. to use at least two contact needle materials for the galvanic filling of the negative molds 4 . Such a multi-phase deposition allows the tip of the needle tip 7 z. B. from a hard but brittle material, the rest of the needle tip 7, however, with a more electrically conductive material such as copper.

In order to improve the effectiveness of the needle tips 7 during scrubbing, these can be inclined relative to the spring clip and the late contact surface, so that an edge is formed whose angle is less than 90 ° (see (2) of FIG. 1). This can be achieved by irradiating the first layer 3 of resist material at an angle of less than 90 °. Such oblique radiation leads to oblique negative shapes 4 . The oblique radiation can e.g. B. as in Fei ertag et al., "Fabrication of three dimensional photonic cry stals by deep X-ray lithography"; Proceedings of the International Symposium on Microsystems, Intelligent Materials and Robots, Sendai, Japan, 1995, pp. 37-40. The technology there still allows oblique radiation at an angle of more than 30 ° to the normal. In the present invention, an angle of 16 ° to Norma len has been found to be particularly advantageous.

After filling the negative molds with 4 contact needle material, the surface can advantageously be mechanically polished in order to allow the application of a further layer of 8 resist material.

The spring clip is preferably formed by separating a further layer 8 of resist material on the first layer 3 of resist material after filling up its negative molds 4 , in which the negative molds 9 for the spring clip 11 are formed (see (3) of FIG . 1). Thereafter, these are formed by galvanic filling with a contact needle material (see (4) of FIG. 1).

The negative forms in the different layers of Re resist material are preferably formed by the resist material rial is suitably irradiated through a mask. This can e.g. B. with light or by means of synchrotron radiation, as described above for the LIGA technology. The mas  ke forms the intended structures of the negative form in the resist material. After that, the resist material developed in the usual way, e.g. B. by removing the be beamed structures. Remain in the residual resist material now the negative forms, which are then galvanically filled can be.

After needle tip 7 and spring clip 11 have each been formed galvanically, the resist material of the layers 3 , 8 is removed, so that only the material introduced remains. This can take place before or preferably after the arrangement has been lifted off the base 2 .

The negative forms of the first and second layers of Re Sist material must be exactly aligned to each other make sure the needle tips are in the right place are arranged on the spring clips. This can be advantageous alignment marks are used as they are e.g. B. in Schmidt et al., "Aligned Double Exposure in Deep X- ray Lithography ", Microelectronic Engineering 30, 235 (1996) are described.

The material used to fill the negative molds can in principle be any material suitable for galvanic filling. When selecting, hardness and electrical conductivity must also be taken into account, and the bending behavior must be taken into account in order to ensure the desired spring constant of the spring clip. Basically suitable, preferred materials are copper, nickel and tungsten boride. The needle tip and spring clip can be made from the same material. However, it is also possible to manufacture the needle tip 7 from a different material than the spring clip 11 and / or from several different materials, so as to provide the optimal material for the respective area of the contact needle. In this case, the compatibility of the two materials must be ensured, since the spring clip material is in direct contact with the material of the needle tip 7 during the galvanic deposition.

Preferably, several contact needles 1 are made simultaneously. These can be connected to one another by retaining brackets 13 (see (6) of FIG. 1) in order to simplify the subsequent release from the resist material. After removal of the resist material, the holding brackets are then attached to e.g. B. at tapering areas 12 cut to obtain individual contact needles 1 .

In a particularly preferred embodiment, the contact needles 1 are arranged so that their needle tips 7 already correspond to the manufacture in the arrangement of the arrangement of an integrated circuit that will be tested later with this arrangement of contact needles 1 . In this case, the contact needles 1 are not isolated in the arrangement next, but the entire arrangement on a carrier, for. B. a circuit board, fixed by the Fe derbügel 11 glued or (for copper) bonded. After fixing the arrangement on the carrier, the contact needles 1 can then be isolated and connected to respective electrical contacts, via which the test voltages can be applied later. In this way, a particularly advantageous embodiment of the present invention can be achieved. Due to the transfer of the overall arrangement, no manual attachment and alignment of the contact needles is required. The high precision of the microtechnical production can also be fully transferred to the overall test card. The high integration densities possible in the manufacture according to the invention enable a correspondingly increased integration density in the resultant test cards in a simple and inexpensive manner.

While the needle tips 7 in this preferred embodiment correspond in their arrangement to the arrangement of the contact surfaces on the target circuit, the structure of the entire test card can be taken into account in the arrangement of the associated spring clips 11 . It can e.g. B. the spring clip 11 are arranged radially, so that the distances between the contacts of the spring clip 11 to the probe card contacts are greater than the distances between the needle tips 7th Such an arrangement simplifies the manufacture of the carrier, since simpler technologies can be used for lower packing densities. The individual contact needles 1 can be connected to each other with this radial arrangement during their manufacture by a retaining ring.

In a further embodiment, two or more layers 8 of resist material are used to form the spring clips 11 . This makes it possible to achieve an even higher Pac density density at needle tips 7 , so that integrated circuits with a high degree of integration can also be produced without the spring clips 11 spatially obstructing themselves. In this embodiment, after filling the needle tips 7 , a further layer 8 of resist material is first applied, in which spring clips 11 are provided for part of the needle tips 7 (for example, for every other needle tip), while over the other needle tips 7 simple passages are provided, which form the contact surfaces for spring clips 11 , which are formed in a further layer 8 of resist material. In this way, two or more superimposed arrangements of spring clips 11 can be formed, which are separated from one another in the vertical spatial direction. This can be exploited that, depending on the target, the spring constant of each contact needle 7 through the mask specification and the choice of Kontaktnadelmate rials set or despite complicated geometry by adjusting the dimensions such as length and diameter, the spring constant can be brought to the same value.

The following is a second main embodiment of the above described invention. This is a process that further simplifies manufacturing of contact needle assemblies.

According to the invention, a contact needle arrangement for an integrated circuit in the for the first main type described as a matrix or a Mu most manufactured. The arrangement thus obtained, however not built into a test card, but serves the manufacturer development of a negative form from a suitable polymer. This Negative form can be made in a known manner, such as e.g. B. by hot stamping or injection molding around the contact needle l arrangement around. The negative form, once made, can now be used as a galvano mold for repetitive, galvani molds of other contact needle arrangements are used become. Thus, it is possible after a one-time, micro technical manufacture of a contact needle arrangement on a cheaper method to switch. If necessary, must in the manufacture of the output contact needle assembly be seen that the negative form made of polymer during curing may be subject to a shrinking process. The exit con The stylus arrangement should then be an appropriate amount are made larger than the Kon clock needle arrangement should be.

The method according to the invention provides novel contact needles available that are simple and therefore inexpensive to manufacture let what the total cost of the needle equipped with it cards or other contacting of integrated circuits lowers. If the contact needles according to a preferred Ausge design as it is shown later on the test card  are arranged, manufactured, there is no manual work Step of assembling the needles entirely, which is another, brings drastic cost reduction. It can be Contact needles with the highest precision in the range of 1 µm manufacture and align. It is only a one-off Adjustment of the overall arrangement on the carrier necessary. All Manufacturing steps are suitable for mass production. The The method also has the advantage that the spring constants with highest precision can be manufactured. The can continue Packing density can be increased extremely.  

Reference list

1

Contact pin

2nd

Wafer

3rd

First layer of resist material

4th

Irradiated area in the resist material / negative form

5

mask

6

radiation

7

Needle point

8th

Second layer of resist material

9

Irradiated area in the resist material of the second layer / negative form

10th

Second mask

11

Spring clip

12th

Rejuvenation area

13

Bracket

Claims (23)

1. A method for the simultaneous production of at least one contact needle ( 1 ) with needle tip ( 7 ) and spring clip ( 11 ), characterized by the following steps:

• A) Galvanic formation of the needle tips ( 7 ) in the structures of a layer of resist material ( 3 )
• B) Galvanic formation of the spring clip ( 11 ) attached to the needle tip ( 7 ) in the structures of at least one further resist layer ( 8 ) which is arranged on the first resist layer ( 3 ).
• C) Remove the resist material.

2. The method according to claim 1, characterized in that step A comprises the following substeps:

• 1. Coating a substrate ( 2 ) with the first layer of resist material ( 3 )
• 2. Forming negative molds ( 4 ) for the needle tips ( 7 ) in the resist material ( 3 )
• 3. Galvanic filling of the negative molds ( 4 ) with at least a first contact needle material.

3. The method according to claim 2, characterized in that the galvanic filling with at least two contact pins materials in a row. 4. The method according to any one of the preceding claims, characterized in that step B comprises the following substeps:

• 1. Application of a further layer of resist material ( 8 )
• 2. Forming negative molds ( 9 ) for at least the spring clip ( 11 ) of the contact needles ( 1 ) in the further layer Re sistmaterial ( 8 ) so that the spring clip ( 11 ) in the arrangement of the needle tips ( 7 ) are adjusted
• 3. Galvanic filling of the negative molds ( 9 ) with a second contact needle material.

5. The method according to any one of the preceding claims, characterized in that the molding of the negative molds ( 4 , 9 ) comprises the following steps:

• a) irradiation of the resist material ( 3 , 8 ) through a mask ( 5 , 10 )
• b) developing the resist material ( 3 , 8 ) to remove irradiated areas.

6. The method according to any one of the preceding claims, characterized by the further step:

• A) coating the needle tip ( 7 ) and / or the spring clip with a further contact needle material.

7. The method according to any one of the preceding claims, characterized in that a plurality of contact needles ( 1 ) are arranged so that they correspond to the arrangement of contact surfaces of an integrated circuit. 8. The method according to claim 7, characterized in that went through the sub-steps B1-B3 at least once more leads. 9. The method according to claim 8, characterized in that in each of the further layers of resist material ( 8 ), with the exception of the top layer, negative molds for extensions of those needle tips ( 7 ) are formed, which are used to connect the needle tips ( 7 ) with the spring clips ( 11 ) serve in the next of the further layers of resist material ( 8 ). 10. The method according to any one of claims 7 to 9, characterized in that a plurality of contact needles ( 1 ) are arranged so that the Fe derbügel ( 11 ) point radially away from the needle tips ( 7 ) under supervision. 11. The method according to any one of the preceding claims, characterized in that the contact needles ( 1 ) are interconnected by at least one Hal tebügel ( 13 ) which is formed in the further layer Re sistmaterial ( 8 ). 12. The method according to any one of the preceding claims, characterized in that the negative molds ( 4 ) for the needle tips ( 7 ) are formed at an angle of less than 90 ° to the surface of the layer of Re sistmaterial ( 3 ). 13. The method according to any one of the preceding claims, characterized in that the first and second contact needle materials are selected from Copper, nickel and tungsten boride. 14. The method according to any one of the preceding claims, characterized in that the first and the second contact needle material are identical.   15. A method for producing a mold for contact needles ( 1 ), characterized by the following steps:

• 1. Manufacture of a contact needle arrangement according to one of the preceding claims,
• 2. Production of a polymer mold according to this contact needle arrangement.

16. Contact needle ( 1 ) for producing electrical contacts to semiconductor circuits, characterized by a galvanically formed spring clip ( 11 ) made of at least egg nem first contact needle material and a galvanically formed needle tip ( 7 ) made of at least a second contact needle material, which is at an angle on the spring clip ( 11 ) is arranged. 17. Contact needle ( 1 ) according to claim 15, characterized in that the first and second contact needle material are selected from copper, nickel and tungsten boride. 18. Contact needle ( 1 ) according to claim 16 or 17, characterized in that the first and the second contact needle material are identical. 19. Test card for testing integrated circuits, characterized in that it comprises contact needles ( 1 ) according to one of claims 16 to 19 or manufactured according to one of claims 1 to 15. 20. test card according to claim 19, characterized in that  it includes a contact needle assembly attached to a support is attached. 21. Test card according to claim 19 or 20, characterized in that the spring clips ( 11 ) are electrically connected to contacts on the carrier. 22. Use of contact needles ( 1 ) according to one of claims 16 to 19 or produced according to one of claims 1 to 15 for test cards. 23. Use of contact needles ( 1 ) according to one of claims 16 to 19 or manufactured according to one of claims 1 to 15 for contacting integrated circuits in their Ge housings.