Electronic components with terminals and spring contact elements extending from areas which are remote from the terminals

What is claimed is:

1. An electronic component, comprising:

a terminal on the electronic component;

a first remote area on the component which is remote from the terminal;

an electrical connection between the terminal and the first remote area; and

a first spring contact element disposed at the first remote area, the spring contact element further comprising:

a precursor element, of a first material, attached to and extending from the first remote area; and

a second material deposited in a form determined significantly by the precursor element, wherein the precursor element without the second material is flexible, and the second material is resilient.

2. The electronic component, according to claim 1, wherein:

the electrical connection comprises a conductive trace having a proximal end joined to the terminal; and

the first remote area comprises a position on the conductive trace which is remote from the proximal end of the conductive line.

3. The electronic component, according to claim 1, further comprising:

a plurality of terminals on the electronic component;

a plurality of first remote areas on the electronic component;

a plurality of electrical connections, each of the plurality of electrical connections extending between selected ones of the terminals and selected ones of the first remote areas; and

a plurality of spring contact elements, each of the plurality of spring contact elements disposed at a one of the remote areas.

4. The electronic component, according to claim 3, further comprising:

a first layer on the electronic component having a first pattern of first conductive traces;

a second layer on the electronic component having a second pattern of second conductive traces;

selected portions of the first conductive traces joined to selected ones of the terminals; and

selected portions of the second conductive traces electrically connected to selected ones of the first conductive traces;

wherein the first remote areas are on the second conductive traces.

5. The electronic component, according to claim 4, further comprising:

a third layer on the electronic component having a third pattern of third conductive traces;

wherein the selected portions of the second conductive traces electrically are connected to the selected ones of the first conductive traces via selected portions of the third conductive layer.

6. The electronic component, according to claim 3, wherein:

the electrical connections comprise a plurality of conductive lines; and

at least one of the plurality of conductive lines crosses over another one of the plurality of conductive lines without electrically contacting the other one of the conductive lines.

7. The electronic component, according to claim 3, wherein:

the spring contact elements are substantially identical to one another.

8. The electronic component, according to claim 3, wherein:

the plurality of terminals are disposed in a first pattern on the component;

each of the plurality of spring contact elements has a contact region, the contact region displaced away from the electronic component and moveable toward the electronic component;

the contact regions of the spring contact elements are arranged in a second pattern; and

the second pattern is different from the first pattern.

9. The electronic component, according to claim 8, wherein:

the first pattern comprises a peripheral pattern having a first pitch; the second pattern comprises a peripheral pattern having a second pitch; and

the second pitch is different than the first pitch.

10. The electronic component, according to claim 8, wherein:

the second pattern comprises a row.

11. The electronic component, according to claim 8, wherein:

the first pattern comprises a row.

12. The electronic component, according to claim 3, wherein:

each of the plurality of spring contact elements has a contact region, the contact region displaced away from the electronic component and moveable toward the electronic component;

the plurality of terminals are disposed in a peripheral pattern on the component; and

the plurality of contact regions of the spring contact elements are arranged in an area array.

13. The electronic component, according to claim 1, further comprising:

a second remote area on the electronic component, the second remote area electrically connected to the terminal; and

a second spring contact element disposed at the second remote area.

14. The electronic component, according to claim 1, wherein:

the first spring contact element is a composite interconnection element.

15. The electronic component, according to claim 1, wherein:

the first spring contact element is a plated-up structure.

16. The electronic component, according to claim 1, wherein:

the electronic component is selected from the group consisting of a semiconductor device, a memory chip, a portion of a semiconductor wafer, a space transformer, a probe card, a chip carrier, and a socket.

17. A semiconductor device with an integral contact element, comprising:

a semiconductor device;

a bond pad on the semiconductor device;

a conductive trace on the semiconductor device extending from the bond pad to a position which is remote from the terminal;

a spring contact element having a base end at a region of the conductive trace which is remote from the bond pad, the spring contact element having a contact region disposed above the surface of the substrate and offset from the base end,

the spring contact element further comprising:

a precursor element, of a first material, attached to and extending from the first remote area; and

a second material deposited in a form determined significantly by the precursor element, wherein the precursor element without the second material is flexible, and the second material forms a spring.

18. The semiconductor device, according to claim 17, wherein:

the spring contact element comprises a composite interconnection element.

19. The semiconductor device, according to claim 17, wherein:

the spring contact element comprises a plated-up structure.

20. The semiconductor device, according to claim 17, wherein:

the semiconductor device is a memory chip.

21. The electronic component, according to claim 1, wherein the first material includes a material selected from the group consisting of gold, aluminum and copper.

22. The electronic component, according to claim 1, wherein the spring contact element is resilient and the second material dominates the resiliency of the spring contact element.

23. The electronic component, according to claim 1, wherein the second material is stronger than the precursor element.

24. The electronic component, according to claim 1, wherein the second material is a coating which envelops the precursor element.

25. The electronic component, according to claim 1, wherein the second material comprises a material selected from the group consisting of nickel, cobalt and iron.

26. The electronic component, according to claim 1, wherein the second material is deposited directly on the precursor element.

27. The semiconductor device, according to claim 17, wherein the first material includes a material selected from the group consisting of gold, aluminum and copper.

28. The semiconductor device, according to claim 17, wherein the spring contact element is resilient and the second material dominates the resiliency of the spring contact element.

29. The semiconductor device, according to claim 17, wherein the second material is stronger than the precursor element.

30. The semiconductor device, according to claim 17, wherein the second material is a coating which envelops the precursor element.

31. The semiconductor device, according to claim 17, wherein the second material comprises a material selected from the group consisting of nickel, cobalt and iron.

32. The semiconductor device, according to claim 17, wherein the second material is deposited directly on the precursor element.

Description Submit all comments and votes

TECHNICAL FIELD OF THE INVENTION

The present invention relates to resilient (spring) contact (interconnection) elements (structures) suitable for effecting connections between electronic components and, more particularly, to microminiature spring contact elements.

BACKGROUND OF THE INVENTION

Commonly-owned U.S. patent application Ser. No. 08/152,812 filed Nov. 16, 1993 (now U.S. Pat. No. 5,476,211, issued Dec. 19, 1995), and its counterpart commonly-owned copending "divisional" U.S. patent applications Ser. Nos. 08/457,479 filed Jun. 1, 1995 (status: pending) and 08/570,230 filed Dec. 11, 1995 (status: pending), disclose methods for making resilient interconnection elements (spring contact elements) for microelectronics applications involving mounting an end of a flexible elongate core element (e.g., wire "stem" or "skeleton") to a terminal on an electronic component, coating the flexible core element and adjacent surface of the terminal with a "shell" of one or more materials having a predetermined combination of thickness, yield strength and elastic modulus to ensure predetermined force-to-deflection characteristics of the resulting spring contacts. Exemplary materials for the core element include gold. Exemplary materials for the coating include nickel and its alloys. The resulting spring contact element is suitably used to effect pressure, or demountable, connections between two or more electronic components, including semiconductor devices.

Commonly-owned, copending U.S. patent application Ser. No. 08/340,144 filed Nov. 15, 1994 (status: pending) and its corresponding PCT Patent Application No. PCT/US94/13373 filed Nov. 16, 1994 (published as WO95/14314 May 26, 1995, pending), both by KHANDROS and MATHIEU, disclose a number of applications for the aforementioned spring contact elements, and also discloses techniques for fabricating contact pads (contact tip structures) at the ends of the spring contact elements.

Commonly-owned, copending U.S. patent application Ser. No. 08/452,255 filed May 26, 1995 (status: pending) and its corresponding PCT Patent Application No. PCT/US95/14909 filed Nov. 13, 1995 (published as WO96/17278 Jun 6, 1996, pending) disclose additional techniques and metallurgies for fabricating spring contact elements as composite interconnection structures and for fabricating and mounting contact tip structures to the free ends (tips) of the composite interconnection elements.

Commonly-owned, copending U.S. patent application Ser. No. 08/819,464 filed Mar 17, 1997 (status: pending) and its counterpart PCT Patent Application No. US97/08606 filed May 15, 1997 (status: pending) disclose a technique whereby a plurality of elongate tip structures having different lengths than one another can be arranged so that their outer ends are disposed at a greater pitch than their inner ends. Their inner, "contact" ends may be collinear with one another, for effecting connections to electronic components having terminals disposed along a line, such as a centerline of the component. Additional contact tip structure methods and apparatus are disclosed in these patent commonly-owned applications.

The present invention addresses and is particularly well-suited to making interconnections to modern microelectronic devices (components) having their terminals (bond pads) disposed at a fine-pitch. As used herein, the term "fine-pitch" refers to microelectronic devices that have their terminals disposed at a spacing of less than 5 mils, such as 2.5 mils or 65 .mu.m. As will be evident from the description that follows, this is preferably achieved by taking advantage of the close tolerances that readily can be realized by using lithographic rather than mechanical techniques to fabricate the contact elements.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved technique for fabricating spring contact elements.

Another object of the invention is to provide a technique for fabricating spring contact elements using processes that are inherently well-suited to the fine-pitch close-tolerance world of microelectronics.

Another object of the invention is to provide a technique for fabricating microminiature spring contact elements directly on active electronic components, such as semiconductor devices, without damaging the semiconductor devices. This includes fabricating microminiature spring contact elements on semiconductor devices resident on a semiconductor wafer, prior to their being singulated therefrom.

Another object of the invention is to provide a technique for fabricating spring contact elements that are suitable for socketing (releasably connecting to) electronic components such as semiconductor devices, such as for performing burn-in on said devices.

Another object of the invention is to provide a technique for fabricating spring contact elements which provide space translation of the terminals of an electronic component to which they are mounted. As used herein, the term "space translation" means that the tips (distal ends) of the spring contact elements are disposed at different spacing (pitch) and/or orientation than the terminals of the electronic component to which they are connected.

According to the invention, a spring contact element is fabricated on an electronic component such as an active semiconductor device, a memory chip, a portion of a semiconductor wafer, a space transformer, a probe card, a chip carrier, or a socket, at a position on the electronic component which is remote (spatially translated) from a terminal to which it is electrically connected. The electrical connection between the spring contact element and the terminal is suitably a conductive line originating at the terminal. The spring contact element is free-standing, having a base end which is mounted to the electronic component, such as at a position on the conductive line which is remote from the terminal, a contact (tip) end, and a resilient main body portion between the base end and the tip end.

The spring contact elements are any resilient, freestanding contact structures. An example of a resilient, freestanding contact structure is disclosed in commonly-owned U.S. Pat. No. 5,476,211 issued Dec. 19, 1995, which is incorporated by reference herein. Another example of a resilient, freestanding contact structure is disclosed in commonly-owned, copending U.S. patent application Ser. No. 08/802,054 filed Feb. 18, 1997 (status: pending) and its counterpart PCT Patent Application No. US97/08271 filed May 15, 1997 (status: pending), as well as in the aforementioned US97/08634.

According to an aspect of the invention, a plurality spring contact elements are mounted to an electronic component and electrically connected to a corresponding plurality of terminals on the electronic component in a manner to effect "space translation"--in other words, so that the layout and/or pitch of the component terminals is different than the layout and/or pitch of the tips of the spring contact elements. For example, the terminals of the electronic component are disposed at a first pitch in a peripheral pattern and the tips of the spring contact elements are disposed in an area array at a second pitch, or vice-versa.

The aforementioned U.S. patent application Ser. No. 08/340,144 and PCT Patent Application No. US94/13373 disclose a one type of pitch-translation which is effected by shaping selected ones of the free-standing resilient contact structures differently than other one of the free-standing resilient contact structures. See FIGS. 23 and 24 therein. Such a technique has the drawback that different "style" spring contact elements need to be designed, manufactured and mounted to a single electronic component. This can cause problems in processing, particularly if certain steps in the manufacturing process have narrow process windows.

According to an aspect of the invention, a plurality of spring contact elements are manufactured so that they are substantially similar (such as identical) to one another, and space-translation is effected by tailoring a relatively process-insensitive part of the overall spring contact elements. To wit, at least some of, including all of, the spring contact elements on a given electronic component are provided with elongate "tails", which may be conductive lines extending from the base end of the spring contact element to the terminal of the electronic component to which it is electrically connected.

In an embodiment of the invention, the tails are elongate conductive lines formed using conventional semiconductor processing techniques extending along the surface of the component. A one (proximal) end of the conductive line overlies a terminal (e.g., bond pad) of the electronic component and is joined thereto. The base end of a spring contact element is joined to an other position on the conductive line, such as at the remote (distal) end of the conductive line. This embodiment is suited to fabricating spring contact elements which are composite interconnection elements directly upon the conductive line which effects space translation. This embodiment is also suited to joining pre-fabricated spring contact elements to the remote positions on the conductive lines.

In another embodiment of the invention, the tails are elongate conductive lines formed using conventional semiconductor processing techniques extending along the surface of the component. A one (proximal) end of the conductive line overlies a terminal (e.g., bond pad) of the electronic component. The base end of a spring contact element is integrally formed with an other remote (distal) end of the conductive line. This embodiment is well suited to manufacturing spring contact elements which are plated-up structures and the elongate conductive line tails extending to terminals of the electronic component in one fell swoop.

According to an aspect of the invention, the tails of the spring contact elements can extend in a straight line (linearly) along the surface of the electronic component to the base end of the spring contact element to effect "simple" space-translation such as fan-out (or fan-in). Or, the tails of the spring contact elements can "wander" (or meander) along the surface of the electronic component including, if necessary crossing over one another to effect more complex space-translation schemes.

A benefit of the present invention is that the contact layout of an existing electronic component can be modified, after the electronic component has already been completely manufactured. For example, a completed (finished) semiconductor device has a number of bond pad terminals accessible on a surface thereof through openings in a passivation layer. If a plurality of identical spring contact elements were mounted to or fabricated upon those terminals, the tips of the spring contact elements would mirror the layout of the bond pads. The present invention essentially "relocates" the terminals (at least a portion thereof) so that the tips of the spring contact elements can have a completely different layout than the bond pads of the semiconductor device. The tails or conductive lines of the present invention have a proximal end which is directly atop an existing terminal of an existing electronic component and a remote region (such as a distal end) which, in essence, serves as a "relocated terminal" for the electronic component.

The spring contact elements of this invention are suitable for making either temporary or permanent electrical connections to terminals of another electronic component such as a printed circuit board (PCB) interconnection substrate.

For making temporary connections, the component upon which the spring contact elements are fabricated is brought together with another electronic component so that the tip ends of the spring contact elements are in pressure contact with terminals of the other electronic component. The spring contact elements react resiliently to maintain contact pressure and electrical connections between the two components.

For making permanent connections, the component upon which the spring contact elements are fabricated is brought together with another electronic component, and the tip ends of the spring contact elements are joined, such as by soldering or brazing or with a conductive adhesive, to terminals of the other electronic component. The spring contact elements are compliant, and accommodate differential thermal expansion between the two electronic components.

The spring contact element is suitably formed of at least one layer of a metallic material selected for its ability to cause the resulting contact structure to function, in use, as a spring (i.e., exhibit elastic deformation) when force is applied to its contact (free) end.

The spring contact elements of the present invention can be fabricated directly on the surface of a semiconductor device, or on the surfaces of a plurality of semiconductor devices resident on a semiconductor wafer. In this manner, a plurality of semiconductor devices resident on a semiconductor wafer can be "readied" for burn-in and/or test prior to being singulated from the semiconductor wafer.

Other objects, features and advantages of the invention will become apparent in light of the following description thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will be made in detail to preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. The drawings are intended to be illustrative, not limiting. Although the invention will be described in the context of these preferred embodiments, it should be understood that it is not intended to limit the spirit and scope of the invention to these particular embodiments. Certain elements in selected ones of the drawings are illustrated not-to-scale, for illustrative clarity. Often, similar elements throughout the drawings are referred to by similar references numerals. For example, the element 199 may be similar in many respects to the element 299 in another figure. Also, often, similar elements are referred to with similar numbers in a single drawing. For example, a plurality of elements 199 may be referred to as 199a, 199b, 199c, etc.

FIG. 1A is a side cross-sectional view of a technique for making a spring contact element which is a composite interconnection element, according to the invention.

FIG. 1B is a side cross-sectional view of a further step in the technique for making the spring contact element of FIG. 1A, according to the invention.

FIG. 1C is a side cross-sectional view of a further step in the technique for making the spring contact element of FIG. 1B, according to the invention.

FIG. 2A is a side cross-sectional view of a technique for making a spring contact element which is a plated-up structure, according to the invention.

FIG. 2B is a side cross-sectional view of a further step in the technique for making the spring contact element of FIG. 2A, according to the invention.

FIG. 2C is a perspective view of a further step in the technique for making the spring contact element of FIG. 2B, according to the invention.

FIG. 3 is a perspective view of an electronic component having a plurality of spring contact elements mounted to terminals thereof.

FIG. 4 is a perspective view of a technique for forming conductive lines on an existing electronic component.

FIG. 5A is a perspective view of a technique for effecting space-translation with spring contact elements which are composite interconnection elements, according to the invention.

FIG. 5B is a perspective view of a technique for effecting space-translation with spring contact elements which are plated-up structures, according to the invention.

FIG. 6A is a schematic (stylized) plan view illustration of an application (use) for the spring contact elements having extended tails, according to the invention.

FIG. 6B is a cross-sectional view, taken on a line 6B--6B through FIG. 6A, according to the invention.

FIG. 7A is a schematic (stylized) plan view illustration of another application (use) for the spring contact elements having extended tails, according to the invention.

FIG. 7B is a cross-sectional view, taken on a line 7B--7B through FIG. 7A, according to the invention.

FIG. 8A is a perspective view of two spring contact elements which are "composite interconnection elements" mounted to distal regions of a conductive line emanating from a terminal of an electronic component, according to the invention.

FIG. 8B is a perspective view of two spring contact elements which are "plated-up structures" mounted to distal regions of a conductive line emanating from a terminal of an electronic component, according to the invention.

FIG. 9 is a schematic plan view of an existing terminal of an electronic component, a "relocated terminal" and a connection therebetween, according to the invention.

FIG. 9A is a perspective view of a technique for forming a relocated terminal on an electronic component, and effecting an electrical connection to an existing terminal of the component, according to the invention.

FIG. 9B is a cross-sectional view, taken on a line 9B--9B through FIG. 9A, according to the invention.

FIG. 10 is a schematic plan view of a first step of mounting or fabricating spring contact elements to relocated terminals on an electronic component, according to the invention.

FIGS. 10A-10C are side-cross sectional views, taken on a line 10--10 through FIG. 10 of an embodiment of a technique for mounting or fabricating spring contact elements to relocated terminals on an electronic component, according to the invention.

FIGS. 10D-10G are side-cross sectional views, taken on a line 10--10 through FIG. 10 of another embodiment of a technique for mounting or fabricating spring contact elements to relocated terminals on an electronic component, according to the invention.

FIGS. 11A-11C are cross-sectional views of a technique for mounting previously manufactured spring contact elements which are composite interconnection elements to conductive lines on an electronic component, according to the invention.

FIGS. 12A-12C are cross-sectional views of a technique for mounting previously manufactured spring contact elements which are plated-up structures to conductive lines on an electronic component, according to the invention.

FIGS. 13A and 13B are cross-sectional views of a technique for mounting previously manufactured contact tip structures to spring contact elements which are resident on conductive lines (extended tails), according to the invention.

FIG. 14A is a cross-sectional view of a technique for making multi-level conductive lines on an electronic component, according to the invention.

FIG. 14B is a perspective view, partially broken away, of a technique for making conductive lines which cross over one another on an electronic component, according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

The section headings appearing in the description that follows are included as an aid to the reader, and are not to be construed in a limiting manner.

An Exemplary Spring Contact Element

The aforementioned commonly-owned U.S. Pat. No. 5,476,211 and PCT Patent Application No. US94/13373 disclose techniques for fabricating elongate free-standing resilient contact structures (spring contact elements which are composite interconnection elements) on electronic components by bonding and shaping an elongate core element (e.g., a gold wire) on a terminal of the component and overcoating the free-standing core element and an adjacent area (e.g., the terminal) of the component with a metallic material which dominates the mechanical characteristics of the resulting composite interconnection element and securely anchors the resulting composite interconnection element to the terminal of the component.

The aforementioned PCT Patent Application No. US95/14909 discloses, at FIGS. 1C, 1D and 1E thereof, reproduced herein as FIGS. 1A, 1B and 1C, discloses an exemplary technique for fabricating spring contact elements of the aforementioned composite interconnection type on electronic components which are semiconductor devices. This technique is also disclosed at FIGS. 3A, 3B and 3C of commonly-owned, copending PCT Patent Application No. US95/14885 filed Nov. 15, 1995 (published May 23, 1996 as WO96/15459).

FIGS. 1A, 1B and 1C illustrate an exemplary technique for fabricating resilient, elongate, free-standing spring contact elements which are composite interconnection elements on an electronic component 108 which is a semiconductor device wherein a free end 102a of a wire 102 is fed through a capillary 104 and is bonded to a surface of the semiconductor device 108. In this technique, a conductive layer 120 is first disposed on the surface of the component 108. This layer 120 may be a top metal layer, which is normally intended for bond-out, as defined by openings 122 in a passivation layer 124 (typically nitride). In this manner, a bond pad would be defined which would have an area corresponding to the area of the opening 122 in the passivation layer 124. Normally (i.e., according to the prior art), a wire would be bonded to the bond pad. A blanket layer 126 of metallic material (e.g., aluminum) is deposited over the passivation layer 124 in a manner that the conductive layer 126 conformally follows the topography of the passivation layer 124, including "dipping" into the opening 122 and electrically contacting the layer 120. A patterned layer 128 of photoresist is applied over the layer 126 with openings 132 aligned over the openings 122 in the passivation layer 124. A feature of this technique is that the opening 132 is larger than the opening 122. This results in a larger bond area (defined by the opening 132) than is otherwise (as defined by the opening 122) present on the semiconductor die (108). The free end 102a of the wire 102 is bonded to the top (as viewed) surface of the conductive layer 126, within the opening 132. Next the wire is configured to have a spring shape and is severed to create a free-standing "wire stem". Next, the wire stem and adjacent area of the component 108 within the opening 132 is overcoated (e.g., plated) with one or more layers of a metallic material (e.g., nickel), resulting in a spring contact element which is a freestanding elongate composite interconnection structure. As shown in FIGS. 1B and 1C, the material 134 overcoating the wire stem completely envelops the wire stem and also covers the conductive layer 126 within the area defined by the opening 132 in the photoresist 128. The photoresist 128 is then removed (such as by chemical etching, or washing), and the substrate is subjected to selective etching (e.g., chemical etching) to remove all of the material from the conductive layer 126 except that portion of the layer 126 which is covered by the material 134 overcoating the wire stem. This results in the structure shown in FIG. 1C, a significant advantage of which is that the resulting spring contact element 130 is securely anchored (by the coating material 134) to an area (which was defined by the opening 132 in the photoresist) which can easily be made to be larger than what would otherwise (e.g., in the prior art) be considered to be the contact area of a bond pad (i.e., the opening 122 in the passivation layer 124). The spring contact element 130 shown in FIG. 1C is a composite interconnection element which is elongate and has a base (proximal) end which is mounted to the semiconductor device 108 and free (distal) end (tip) at its opposite end for making a pressure contact with a terminal (not shown) of another electronic component (not shown).

Exemplary materials, processes and dimensions

Exemplary materials for the wire 102 include, but are not limited to: gold, aluminum, copper, and their alloys. These materials are typically alloyed with small amounts of other metals to obtain desired physical properties, such as with beryllium, cadmium, silicon, magnesium, and the like. It is also possible to use silver, palladium, platinum; metals or alloys such as metals of the platinum group of elements. Solder constituted from lead, tin, indium, bismuth, cadmium, antimony and their alloys can be used.

Exemplary materials for the overcoat 134 include, but are not limited to: nickel, and its alloys; copper, cobalt, iron, and their alloys; gold (especially hard gold) and silver, both of which exhibit excellent current-carrying capabilities and good contact resistivity characteristics; elements of the platinum group; noble metals; semi-noble metals and their alloys, particularly elements of the palladium group and their alloys; tungsten and molybdenum. In cases where a solder-like finish is desired, tin, lead, bismuth, indium and their alloys can also be used.

Exemplary processes for overcoating the core element (wire stem) 102 include, but are not limited to: various processes involving deposition of materials out of aqueous solutions; electrolytic plating; electroless plating; chemical vapor deposition (CVD); physical vapor deposition (PVD); processes causing the deposition of materials through induced disintegration of liquid or solid precursors; and the like, all of these techniques for depositing materials being generally well known.

Exemplary dimensions for the wire 102 are, but are not limited to: a round cross-section wire having a diameter of approximately 1 mil (0.0010 inches) including, but not limited to a diameter in the range of 0.7-2.0 mils, preferably in the range of 0.5-3.0 mils.

It is within the scope of this invention that the wire 102 is in the form of a ribbon, having a non-circular cross-section, of the above-referenced materials. For example, it may be generally rectangular in cross-section, having a first transverse dimension "d1" greater than a second transverse dimension "d2" in a direction orthogonal to the first dimension "d1". The dimension "d1" is preferably at least twice (two times) as large (including three, four, and more) as the dimension "d2". For example:

the dimension "d1" (or width) may be 1-10 mils, for example 5.0 mils; and

the dimension "d2" (or thickness) may be 0.3-1.5 mils, for example 1.0 mils.

Exemplary dimensions for the various layers of a multilayer overcoat 134 are, but are not limited to 0.03 to 5 mils, preferably from 0.05 mils to 3 mils, an overall thickness of the overcoat being on the order of 1-3 mils.

Another Exemplary Spring Contact Element

Commonly-owned, copending U.S. patent application Ser. No. 08/784,862 filed Jan. 15, 1997 (status: pending) and its counterpart PCT Patent Application No. US97/08604 filed May 15, 1997 (status: pending) disclose, for example at FIGS. 6A-6C thereof, a technique for fabricating free-standing resilient (spring) contact elements on an electronic component. Generally, a number of insulating layers having openings formed therein are aligned and "seeded" with a layer of conductive material. A mass of conductive material can then be formed (or deposited) in the seeded opening(s), such as by electroplating (or CVD, sputtering, electroless plating, etc.). After the insulating layers are removed, the masses can function as free-standing resilient contact structures which extend not only vertically above the surface of the component, but also laterally from the location whereat they are mounted. In this manner, the contact structures are readily engineered to be compliant in both the Z-axis as well as in the x-y plane (parallel to the surface of the component). This is described in greater detail hereinbelow with respect to FIGS. 2A-2C.

FIG. 2A illustrates an exemplary technique 200 for fabricating one of a plurality of free-standing resilient (spring) contact elements on a substrate 202 which may be an active electronic component, including semiconductor devices such as memory chips, including semiconductor devices resident on a semiconductor wafer (not shown).

The substrate 202 has a plurality (one of may shown) or areas 212 on its surface whereat the spring contact elements will be fabricated. In the case of the substrate 202 being an electronic component (such as a semiconductor device), these areas 212 would be terminals (such as bond pads) of the electronic component.

Generally, the technique 200 involves applying a number (three shown) of patterned masking layers 204, 206 and 208 having openings onto the surface of the substrate. The layers are patterned to have openings (as shown) aligned with the areas 212, and the openings are sized and shaped so that an opening in a one layer (e.g., 208, 206) extends further from the area 212 than an opening in an underlying layer (e.g., 206, 204, respectively). In other words, the first layer 204 has an opening which is directly over the area 212. A portion of the opening in the second layer 206 is aligned over at least a portion of the opening in the first layer 204 and, conversely, a portion of the first layer 204 extends under a portion of the opening in the second layer 206. Similarly, a portion of the opening in the third layer 208 is aligned over at least a portion of the opening in the second layer 206 and, conversely, a portion of the second layer 206 extends under a portion of the opening in the third layer 208. The bottom portion of a given overall opening is directly over the selected area 212 and its top portion is elevated and laterally offset from its bottom portion. As will be discussed in greater detail hereinbelow, a conductive metallic material is deposited into the openings, and the masking layers are removed, resulting in a freestanding contact structure having been fabricated directly upon the substrate with its base end secured to the substrate 202 at the area 212 and its free end extending both above the surface of the substrate and laterally-displaced from the area 212.

If required, such as for electroplating, a very thin (e.g., 450 .mu.m) "seed" layer of conductive material 214 such as titanium/tungsten (TiW) may be deposited into the openings. Then, a mass of conductive metallic material (e.g., nickel) 220 can be deposit