WO2009044975A1

WO2009044975A1 - Probe card

Info

Publication number: WO2009044975A1
Application number: PCT/KR2008/002047
Authority: WO
Inventors: Hyeong Tae Kim
Original assignee: Korea Instrument Co., Ltd.
Priority date: 2007-10-02
Filing date: 2008-04-11
Publication date: 2009-04-09
Also published as: KR100802087B1

Abstract

A probe card which is useful to inspect large-sized flash wafer chips is disclosed. The probe card for inspecting wafer chips includes probes each having a contact tip which is formed at its upper end and in contact with each of the wafer chips, and a signal transmission tip which is formed at its lower end and transmits an electrical signal of the wafer chip to an outside, a slit disk having fixing rods formed on its upper surface such that the probes are mounted on the fixing rods, interposers which are installed below the slit disk and electrically connected to the signal transmission tips of the probes to transmit signals, a main substrate which is installed below the interposers to transmit electrical signals transmitted from the interposers to an inspection unit, a reinforcing plate coupled to the main substrate to prevent deformation, and bushings for connecting the reinforcing plate and the slit disk.

Description

Description PROBE CARD

Technical Field

[1] The present invention relates to a probe card, and more particularly to a probe card, which is easy to inspect large-sized flash wafer chips, the probe card having a simple, easy and inventive structure, employing probes manufactured through a MEMS process and providing improved electrical characteristics, measurement accuracy and reliability. Background Art

[2] Generally, a silicon rod for semiconductor applications is cut into thin silicon wafers, and circuits are integrated on the silicon wafers through various processes, thereby forming wafer chips.

[3] Before dicing the wafer into chips, a probe card, which is in a direct contact with the wafer chips, is used to detect failure of the individual wafer chips.

[4] The first probe card was manufactured by molding epoxy resin in a probe made of tungsten. Then, the probe card was in contact with a single wafer chip and connected to a tester.

[5] However, since the epoxy type probe card is manufactured by a manual operation, it is difficult to ensure accuracy, which is required as integration density increases. Further, as the tungsten probe is in contact with an aluminum pad serving as a signal line of the wafer chip, an oxide is produced. Accordingly, as the number of measurements increases, an unstable contact resistance problem is generated. Further, frequent cleaning for reducing production of the oxide causes tip damage.

[6] As another conventional technology, a vertical probe card was used. In the vertical probe card, probes of a vertical shape are in contact with pads one to one. Accordingly, there is an advantage of achieving high-density probing. However, since elasticity is required in an individual probe, it is difficult to achieve a fine pitch in the structure. Further, since a space transformer and a ceramic-based plate having holes for fixing pins are necessary, there is a problem of increasing the manufacturing cost.

[7] As another conventional technology, a micro-electro-mechanical system (MEMS) type probe card was used. The MEMS type probe card improves mass productivity and enables various patterns. Also, the MEMS type probe card has excellent responsiveness even in a high frequency band. However, when one probe is replaced, repair is difficult. As a ceramic space transformer is used, the manufacturing cost increases. In a case where the probe card includes a number of probes, it is difficult to embody interposers capable of minimizing influence on the space transformer and it takes a long manufacturing period. Disclosure of Invention

Technical Problem

[8] 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 probe card capable of inspecting large-sized flash wafer chips.

[9] It is another object of the present invention to provide a probe card having reliable probes formed of an optimum material in an optimum design using a MEMS process.

[10] Further, it is another object of the present invention to provide a probe card having a structure which is easy to replace individual probes and capable of reducing a thermal and mechanical influence on the probes in contact with the wafer surface.

[11] Further, it is another object of the present invention to provide a probe card in which interposers for connecting a main substrate and a sub-substrate are connected by inserting a plurality of pins to minimize influences that may occur in coupling of pins.

[12] Further, it is a further object of the present invention to provide a probe card having a simple and reliable structure, which is also easy to be manufactured. Technical Solution

[13] In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of a probe card for inspecting wafer chips comprising: probes each having a contact tip which is formed at its upper end and in contact with each of the wafer chips, and a signal transmission tip which is formed at its lower end and transmits an electrical signal of the wafer chip to an outside; a slit disk having fixing rods formed on its upper surface such that the probes are mounted on the fixing rods; interposers which are installed below the slit disk and electrically connected to the signal transmission tips of the probes to transmit signals; and a main substrate which is installed below the interposers to transmit electrical signals transmitted from the interposers to an inspection unit.

[14] Further, the probe card according to the present invention may further include sub- substrates which are coupled to an upper portion of the slit disk to be connected to the probes, and are connected to the main substrate after reducing the number of patterns through inner common wiring.

[15] Further, the probe card according to the present invention may further include a reinforcing plate which is coupled to the lower surface of the main substrate to prevent deformation due to heat or pressure.

[16] Further, each of the probes entirely may have an upright plate shape and include the contact tip formed at its upper end, the signal transmission tip formed at its lower end, and a probe side insertion groove which is formed at its middle end and is recessed to be inserted and coupled to fixing slits formed on the fixing rods of the slit disk. Further, an alignment indication piece may be formed at a lower end of the contact tip so as to enable alignment after the probe card is mounted in a prober.

[17] In the present invention, the main substrate includes holes to which bushings are inserted, and the slit disk may be fixed to the reinforcing plate disposed below the main substrate through the bushings.

[18] In the present invention, the interposers are formed in a straight pin type. The in- terposers have elliptical holes having a larger diameter than the pin at one side of their end portions. The other side of the interposers is electrically connected to the signal transmission tip of the probe and the sub-substrates through soldering. The portions of the interposers having the elliptical holes are inserted into pattern holes of the main substrate through an insertion jig. The elliptical holes serve as folded springs to be firmly fixed to the pattern holes, thereby enabling electrical connection.

[19] In the present invention, a number of sub-substrate insertion holes may be formed to pass through a body of the slit disk such that the sub-substrates are inserted and installed into the sub-substrate insertion holes. Fixing rods having fixing slits may be positioned between the sub-substrate insertion holes. The interposers disposed below the sub-substrates may have a structure of connecting the sub-substrates and the pads of the main substrates respectively positioned at upper and lower sides.

[20] In the present invention, the contact tip of the probe may be made of rhodium, and a portion of the probe except the contact tip may be made of nickel-cobalt alloy.

[21] In accordance with another aspect of the present invention, the probe card for inspecting wafer chips may include probes entirely having an upright plate shape, each probe having a contact tip which is formed at its upper end and in contact with each of the wafer chips, a signal transmission tip which is formed at its lower end and transmits an electrical signal of the wafer chip to an outside, and a probe side insertion groove which is formed at its middle end and is recessed to be inserted and coupled to fixing slits; a slit disk entirely having a circular plate shape, which includes a number of sub-substrate insertion holes formed to pass through a body of the slit disk such that the probes are inserted and coupled to the sub-substrate insertion holes; sub-substrates entirely having a rod shape, which are inserted into the sub-substrate insertion holes of the slit disk to perform a common wiring function; interposers entirely having a pin shape, which includes one ends coupled to the signal transmission tips of the probes and the sub-substrates and the other ends having elliptical holes inserted into pattern holes of a main substrate and serving as springs to be firmly coupled to the main substrate; the main substrate having the pattern holes to which the elliptical holes of the interposers are inserted and connected, thereby transmitting an electrical signal transmitted through the interposers to an inspection unit; bushings entirely having a hollow cylindrical structure, which pass through the main substrate to couple the slit disk and a reinforcing plate; and the reinforcing plate entirely having a circular plate shape, which is coupled to a lower surface of the main substrate to prevent deformation due to heat or pressure.

Advantageous Effects

[22] According to the present invention, there is provided a probe card for inspecting wafer chips, wherein probes, a slit disk, interposers and a main substrate are manufactured respectively and coupled to each other through minimum fixing operations. Accordingly, it is very easy to manufacture the probe card.

[23] Further, according to the present invention, the slit disk is formed of a ceramic material having a specific thickness. Accordingly, there is a supporting effect against deformation due to intrinsic strength of ceramic. Further, since the ceramic slit disk and the sub-substrates are manufactured and coupled to each other, it is possible to provide an insulation effect between the probes and serve as a preventer for heat deformation of the probes due to insulation and low expansion characteristics of ceramic.

[24] Further, according to the present invention, the slit disk may be formed of an integrated type or split type. In an integrated type slit disk, it is easy to adjust flatness of the probes. Since the sub-substrates are coupled to the slit disk to enable electrical connection, there is an effect of replacing a space transformer having a scale difficult to be realized at low cost. In the split type slit disk, it is possible to enable a parallel manufacturing process. Accordingly, it is possible to reduce the manufacturing period and also possible to replace a damaged part.

[25] Further, according to the present invention, the number of patterns of the sub- substrates connected by a plurality of pins is designed such that common terminals are combined in an inner line region to reduce the number of patterns, thereby reducing the number of patterns of the main substrate. Accordingly, it is possible to reduce multilayer design compared to a case of manufacturing a single main substrate. Since heat transferred to the probes is diffused while passing through the sub-substrates, there is an advantage of reducing heat effect on the main substrate.

[26] Further, according to the present invention, a probe side insertion groove is formed at a middle end of the probe and is inserted and coupled to fixing slits formed on the fixing rods of the slit disk. Accordingly, when the probe is damaged, it is possible to separate and replace only the damaged probe.

[27] Further, according to the present invention, the interposers have elliptical holes formed on the pins and are naturally arranged such that ends of the pins indicate a central portion on the insertion jig to enable insertion of pins. Further, the elliptical holes serve as springs, thereby enabling electrical connection without an external force. Further, since the pins are manufactured at low cost by etching, there is an advantage of reducing the manufacturing cost.

[28] Further, according to the present invention, bushings are inserted between the slit disk and the reinforcing plate to pass through the main substrate, thereby supporting the main substrate without heat effect on the main substrate. That is, the bushings cause spacing to minimize conductive heat by contact between the respective members. Further, the bushings facilitate attachment and detachment with a minimized fixing structure.

[29] Further, according to the present invention, since the contact tip disposed at the upper end of the probe is made of rhodium, it is possible to maintain high hardness. Also, an oxide is not deposited due to an intrinsic shape of the contact tip. Since a portion of the probe except the contact tip is made of nickel-cobalt alloy, it may be hardly influenced even though a force is repeatedly applied thereto. Accordingly, a material and a design of the probes are found out by computer analysis to provide elasticity and strength appropriate for the probes, thereby minimizing a creep phenomenon. Further, a small marking portion is formed below the contact tip disposed at the upper end of the probe to produce an alignment indication piece so as to enable alignment after the probe card is mounted in a prober.

[30] Further, according to the present invention, the reinforcing plate having low heat expansion and high strength is coupled to a lower portion of the main substrate to disperse a force, thereby preventing deformation of the card due to heat or pressure.

Brief Description of the Drawings

[31] 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: [32] Fig. 1 illustrates an exploded perspective view of the probe card according to the embodiment of the present invention; [33] Fig. 2 illustrates a perspective view of a probe according to the embodiment of the present invention;

[34] Fig. 3 illustrates a slit disk and an enlarged view of a portion of the slit disk;

[35] Fig. 4 illustrates an enlarged view of a portion indicated by a circle A shown in

FIG. 1, which shows a state where the probe is installed on the slit disk; [36] Fig. 5 illustrates a perspective view showing a coupling state of interposers and a sub-substrate; and [37] Fig. 6 illustrates a side view of Fig. 5.

Best Mode for Carrying Out the Invention [38] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[39] In the description of the present invention, detailed description of related function and configuration is omitted when it can make main points of the present invention vague. The following terms are defined by considering the function of the present invention and they can be changed according to intention of a user or custom. Thus, definition of terms should be made based on the content of the whole specification.

[40] Hereinafter, a probe card according to the embodiment of the present invention will be described with reference to Figs. 1 to 6.

[41] Fig. 1 illustrates an exploded perspective view of the probe card according to the embodiment of the present invention. Fig. 2 illustrates a perspective view of a probe according to the embodiment of the present invention. Fig. 3 illustrates a slit disk and an enlarged view of a portion of the slit disk. Fig. 4 illustrates an enlarged view of a portion indicated by a circle A shown in FIG. 1, which shows a state where the probe is installed on the slit disk. Fig. 5 illustrates a perspective view showing a coupling state of interposers and a sub-substrate. Fig. 6 illustrates a side view of Fig. 5.

[42] As shown in the drawings, a probe card 100 according to the embodiment of the present invention includes probes 180, sub-substrates 110, a slit disk 120, interposers 130, bushings 140, a main substrate 150 and a reinforcing plate 160.

[43] As shown in Fig. 2, each of the probes 180 is entirely formed in an upright plate shape. The probe 180 includes a contact tip 182 which is formed at its upper end and in contact with a wafer chip (not shown), a signal transmission tip 186 which is formed at its lower end and transmits an electrical signal of the wafer chip to the outside, and a probe side insertion groove 184 which is formed at its middle end and is recessed toward a central portion to be inserted and coupled to fixing slits 124 to be described later.

[44] In this case, preferably, the contact tip 182 of the probe 180 is made of rhodium, which is a rigid metal material having high hardness.

[45] Meanwhile, a portion except the contact tip 182 may be hardly influenced even though a force is repeatedly applied thereto. Accordingly, preferably, the portion except the contact tip 182 is made of nickel-cobalt alloy to have appropriate elasticity and strength within critical stress and also to minimize a creep phenomenon.

[46] Further, an alignment indication piece 188 is additionally formed at a lower end of the contact tip 182 to be extended sideward in order to facilitate alignment after the probe card 100 is mounted in a prober.

[47] As shown in Figs. 3 and 4, the slit disk 120 is preferably formed of a ceramic material and entirely has a circular plate shape. The slit disk 120 is coupled to a number of bushings 140, to be described later, along virtual lines of an outer periphery 128 and a diameter. Further, a number of sub-substrate insertion holes 126 are formed to pass through a body of the slit disk 120. Fixing rods 122 having a number of fixing slits 124 to which the probe 180 is inserted and coupled are formed between the sub- substrate insertion holes 126.

[48] In this case, the slit disk 120 may be formed of an integrated type or split type. In an integrated type slit disk, it is easy to adjust flatness of the probe 180. The slit disk 120 may be formed in a polygonal shape such as a rectangular shape and a hexagonal shape in addition to a circular shape according to the structural demands.

[49] Further, in the split type slit disk, which is split into several parts in a transverse direction, it is possible to enable a parallel manufacturing process. Accordingly, it is possible to reduce the manufacturing period and also possible to replace a damaged part.

[50] The sub-substrates 110 entirely having a rod shape are inserted into the sub- substrate insertion holes 126 of the slit disk 120. The sub-substrates 110 are electrically connected to the main substrate 150 by the interposers 130 disposed therebelow.

[51] As shown in Fig. 5, the interposers 130 are formed in a straight pin shape. The interposers 130 have elliptical holes 132 having a larger diameter than the pin at one side of their end portions. The other side 136 of the interposers 130 is electrically connected to the signal transmission tip 186 of the probe 180 and the sub-substrates 110 through soldering. The portions of the interposers 130 having the elliptical holes 132 are inserted into pattern holes of the main substrate 150 through an insertion jig. The elliptical holes 132 serve as springs to be firmly coupled to the main substrate 150.

[52] The main substrate 150 entirely has a circular plate shape. The main substrate 150 has a number of holes to pass the bushings 140 therethrough and a number of pattern holes to which the portions of the interposers 130 having the elliptical holes 132 are inserted and connected, thereby transmitting an electrical signal from the probe 180 to an inspection unit.

[53] The bushings 140 entirely have a hollow cylindrical structure. The bushings 140 pass through the main substrate 150 and are fixed to the slit disk 120 and the reinforcing plate 160. Accordingly, it is possible to minimize heat effect on the main substrate 150. That is, when the temperature increases, the bushings 140 cause spacing to minimize conductive heat by contact between the respective members.

[54] Further, the bushings 140 facilitate attachment and detachment with a minimized fixing structure.

[55] The reinforcing plate 160 entirely has a circular plate shape. The reinforcing plate

160 is coupled to the lower surface of the main substrate 150, thereby preventing deformation of the main substrate 150, further, the probe card 100 due to heat or pressure.

[56] 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

[57] According to the present invention, there is provided a probe card, which is easy to inspect large-sized flash wafer chips. The probe card according to the present invention having a simple, easy and inventive structure employs probes manufactured through a MEMS process and provides improved electrical characteristics, measurement accuracy and reliability.

Claims

[1] A probe card for inspecting wafer chips comprising: probes each having a contact tip which is formed at its upper end and in contact with each of the wafer chips, and a signal transmission tip which is formed at its lower end and transmits an electrical signal of the wafer chip to an outside; a slit disk having fixing rods formed on its upper surface such that the probes are mounted on the fixing rods; interposers which are installed below the slit disk and electrically connected to the signal transmission tips of the probes to transmit signals; and a main substrate which is installed below the interposers to transmit electrical signals transmitted from the interposers to an inspection unit.

[2] The probe card according to claim 1, further comprising sub-substrates which are coupled to an upper portion of the slit disk to be connected to the probes, and are formed in the same patterns as patterns of the main substrate to reduce the number of patterns by performing an inner common wiring function.

[3] The probe card according to claim 2, further comprising a reinforcing plate which is coupled to a lower portion of the main substrate to prevent deformation due to heat or pressure, wherein a number of sub-substrate insertion holes are formed on a body of the slit disk to pass through the body such that the sub- substrates are inserted and installed into sub-substrate insertion holes.

[4] The probe card according to claim 3, wherein the slit disk is formed of an integrated type in a circular shape or a polygonal shape, or a split type to be split into several parts.

[5] The probe card according to any one of claims 1 to 4, wherein each of the probes entirely has an upright plate shape and includes the contact tip formed at its upper end, the signal transmission tip formed at its lower end, and a probe side insertion groove which is formed at its middle end and is recessed to be inserted and coupled to fixing slits formed on the fixing rods of the slit disk.

[6] The probe card according to claim 5, wherein an alignment indication piece is additionally formed at a lower end of the contact tip of the probe to be extended sideward so as to facilitate alignment.

[7] The probe card according to claim 3, wherein bushings are inserted and coupled to the reinforcing plate and the slit disk to pass through the main substrate so as to support the slit disk.

[8] The probe card according to claim 5, wherein the interposers are formed in a pin type to connect between the sub-substrates and the main substrate and an elliptical hole is formed at one side of the pin type interposer. [9] The probe card according to claim 5, wherein the contact tip of the probe is made of rhodium, and a portion of the probe except the contact tip is made of nickel- cobalt alloy.