JP2009122121A - Reference alignment target of micro electronic spring contact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a micro electronic spring contact having a reference alignment target used in a semiconductor wafer contactor or its similar device, and a method of manufacturing such a target using a sacrifice substrate. <P>SOLUTION: Each alignment target is arranged adjacently to the tip of the contact on a pad. The alignment targets are arranged on the pad not to come into contact with a terminal or any other part of a wafer to be tested. The alignment targets and the contact tip are preferably arranged on the pad in the same lithography step. A selected one of the pad having a similar alignment target and a thing like a pad is attached to the end of the array of elastic contact elements. Therefore, a plurality of alignment targets correctly arranged in relation to a plurality of contact tips on the contactor are disclosed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to semiconductor device test components, and more particularly to reference alignment targets on microelectronic contacts used in probe cards and contactors, similar components.

  Semiconductor device testing, particularly wafer level testing performed before singulating a semiconductor device from a wafer, involves multiple subminiatures each contacting a terminal pad or solder ball on the wafer, or other such terminals. Often done using components such as contactor assemblies with electronic contacts. Since the terminals are arranged on the wafer at a very fine pitch and the corresponding dimensions of the microelectronic contact structure are small, the alignment of the terminals and contacts on the wafer is achieved with the help of special alignment mechanisms and methods. Is done.

  According to one conventional alignment method, at least three alignment targets (sometimes referred to as “reference” alignment targets) are placed on the wafer at an early device manufacturing stage. These target locations are known to be highly accurate with respect to terminals or contact pads on the wafer. There is no relatively accurate alignment target on the contactor. This limits the accuracy of certain contactors that can be placed together such as tungsten wire contact elements. Tungsten wire contacts cannot be placed on the contactor with high accuracy and therefore cannot maintain alignment accuracy with the target on the contactor. However, certain other contactors such as contactors with composite contacts having contact tip structures arranged by lithography, such as disclosed in US Pat. No. 5,864,946 (Eldridge et al.), The spring contact tip is positioned very accurately.

  In order to be generally effective as an alignment target, the target must be placed with an accuracy that is at least half the fine pitch (interval) between adjacent terminals on the wafer. This means that the alignment target must be in a sphere having a diameter as large as half of the terminal spacing on the semiconductor device. For many storage elements having a pitch of about 80 micrometers (3.2 mils), an accuracy of at least about 40 micrometers (1.6 mils) is required accordingly. Since they are formed during the same lithographic steps used to produce electronic features on the wafer, wafer alignment targets can be placed on the wafer with the required accuracy. . Also, contacts placed lithographically on certain contactors can be placed on the contactors with comparable accuracy.

  According to the prior art alignment method, three or more contact tips that are lithographically arranged are selected to serve as alignment targets during subsequent positioning steps. Typically, a relatively small flat area at the distal end of the contact tip is utilized as a visual target. These flat areas are relatively easy to see and characterize the use of commonly used vision systems. By using the alignment target on the wafer and the selected contact tip on the contactor as a reference point, the wafer and contactor are positioned relative to each other, thereby each contact tip on the contactor and on the wafer. A contact with the corresponding terminal is formed. By utilizing this method, it is possible to make contact with an array of terminals arranged at a very fine pitch.

  The previous alignment method has the advantage over the older method in that it can be aligned with terminals arranged at a pitch up to about 40 micrometers, but has certain limitations. One drawback relates to the use of spring contact tips for contactor alignment. During repeated application of contactors, such contact tips can become contaminated with debris (such as metal oxide or organic debris) from the terminals on the wafer under test. Usually, this will not interfere with the electrical action of the contactor, but it may make positioning the selected contact tip difficult with the required degree of accuracy. The target area on the tip of the contact may become unclear or difficult to see. As the pitch to the terminals on the semiconductor to be tested becomes finer and thus the contact tip dimensions become smaller, this limitation of the prior art method becomes more apparent and costly to overcome.

  Accordingly, there is a need to provide an apparatus and method that overcomes the limitations of prior art methods and is still compatible with the mounting principles of vision and positioning systems.

  The present invention provides an apparatus and method for providing a reference alignment target on a contactor that overcomes the limitations of prior art methods. According to one aspect of the present invention, the alignment target is disposed in a region or pad adjacent to the contact tip. The alignment target is placed on the pad so that it does not come into contact with the terminals of the wafer under test or any other part, preferably after repeated use of the contactor, so that no scrap is generated from the contact tip. ing. The alignment target and contact tip are preferably placed on the pad in the same lithography step. In addition, selected ones, such as pads and pads that also have similar alignment targets, are attached to the end of the array of resilient contact elements along with alignment targets and contact tips. Thus, a plurality of alignment targets are provided that are precisely aligned with a plurality of contact tips on the contactor. The alignment target is easily placed with an accuracy in the range of at least about 3-5 micrometers (about 0.1-0.2 mils), thereby enabling a fine pitch of about 20-30 micrometers (0.8-1.2 mils). It can be used to connect to a wafer having terminals disposed thereon. It is believed that higher accuracy can be achieved, such as positioning an alignment target having an accuracy of about 1.5 micrometers (0.06 mil). In addition, the alignment target, including any target thereon, is positioned so as to maintain a debris-free state and is therefore easily placed over essentially the entire life of the contactor. The alignment target is provided in a variety of different shapes, representative examples of which are disclosed herein.

  By considering the following detailed description of the preferred embodiment, those skilled in the art will appreciate not only a more complete understanding of the reference alignment target, but also its additional advantages and purposes. Reference is first made to the accompanying drawings, which are briefly described.

1 is a very large perspective view of a cantilevered microelectronic spring contact having a tip structure according to the present invention with a contact tip and alignment target in the same location, greatly enlarged. FIG. It is a side view of the spring contact shown in FIG. It is a side view of the front-end | tip structure with respect to the spring contactor shown in FIG. FIG. 5 is a plan view of an exemplary alternative tip structure having a co-located contact tip and alignment target for use with a spring contact. FIG. 5 is a plan view of an exemplary alternative tip structure having a co-located contact tip and alignment target for use with a spring contact. FIG. 5 is a plan view of an exemplary alternative tip structure having a co-located contact tip and alignment target for use with a spring contact. FIG. 5 is a side view of the tip portion of a spring contact, showing a circular pad type alignment target and adjacent contact tips. It is a top view of the front-end | tip part of a spring contact, and shows the alignment target of a circular pad type | mold, and an adjacent contact tip. FIG. 2 is a plan view of an exemplary contactor having a plurality of microelectronic spring contacts, a selection of which has a tip structure with the alignment target of the present invention. FIG. 5B is an enlarged plan view of a spring contact and tip structure with alignment targets on the exemplary contactor shown in FIG. 5A. 5B is a more enlarged plan view of a spring contact and tip structure with alignment targets on the exemplary contactor shown in FIG. 5A. FIG. 5B is a further enlarged plan view of a spring contact and tip structure with alignment targets on the exemplary contactor shown in FIG. 5A. FIG. FIG. 5D is a plan view of a tip structure similar to that shown in FIG. 5D with an alternative shape alignment target. 6 is a perspective view of a sacrificial substrate in an exemplary step of manufacturing a plurality of tip structures similar to that shown in FIGS. FIG. 7 is a cross-sectional view of a portion of the sacrificial substrate shown in FIG. 6, forming contact tips and alignment targets in the same location in an exemplary step of forming a spring contact with the alignment target of the present invention. An etched feature for showing. FIG. 3 is a cross-sectional view of a sacrificial substrate and material laminated thereon during an exemplary step of a process for forming a spring contact with an alignment target of the present invention. FIG. 3 is a cross-sectional view of a sacrificial substrate and material laminated thereon during an exemplary step of a process for forming a spring contact with an alignment target of the present invention. FIG. 3 is a cross-sectional view of a sacrificial substrate and material laminated thereon during an exemplary step of a process for forming a spring contact with an alignment target of the present invention. FIG. 6 is a cross-sectional view showing a spring contact and tip structure with alignment targets during an exemplary attachment step. FIG. 6 is a plan view illustrating an alternative structure comprising an alignment target of the present invention and an adjacent spring contact having a relatively small “microchip” contact tip on the contactor. FIG. 8B is a cross-sectional view of the substrate and alternative structure shown in FIG. 8A. FIG. 8D is a cross-sectional view of the sacrificial substrate and the material laminated thereon during an exemplary step of a process for forming a recessed alignment target and adjacent contact tip as shown in FIG. 8B. FIG. 8D is a cross-sectional view of the sacrificial substrate and the material laminated thereon during an exemplary step of a process for forming a recessed alignment target and adjacent contact tip as shown in FIG. 8B. FIG. 8D is a cross-sectional view of the sacrificial substrate and the material laminated thereon during an exemplary step of a process for forming a recessed alignment target and adjacent contact tip as shown in FIG. 8B. FIG. 8D is a cross-sectional view of the sacrificial substrate and the material laminated thereon during an exemplary step of a process for forming a recessed alignment target and adjacent contact tip as shown in FIG. 8B. FIG. 5 is a plan view of an exemplary tip structure during a process step for forming an alignment target using a jig for marking the tip structure after attaching the contact tip. FIG. 5 is a plan view of an exemplary tip structure during a process step for forming an alignment target using a jig for marking the tip structure after attaching the contact tip. FIG. 5 is a plan view of an exemplary tip structure during a process step for forming an alignment target using a jig for marking the tip structure after attaching the contact tip.

  The present invention provides a method and apparatus for providing an accurate reference alignment target on a microelectronic contact and on a contactor carrying a plurality of microelectronic contacts. In the following detailed description, like element numbers are used to describe like elements shown in one or more figures.

  Referring to FIG. 1, in one embodiment of the present invention, an alignment target 116 is provided on the microelectronic spring structure 100. The spring structure 100 can be configured in various ways as is known in the prior art. In the embodiment shown in FIG. 1, the spring structure 100 is configured as disclosed in its co-pending application Ser. No. 09/746716, filed Dec. 22, 2000, which is hereby incorporated by reference. Are hereby incorporated by reference in their entirety. That is, the microelectronic spring structure 100 includes a group of columnar elements or posts 104, a group of columnar elements, a cantilever beam 102 fixed to the group of columnar elements, and a cantilever beam. The contact tip 114 of the distal end portion from the group of columnar elements. In an alternative embodiment, the post elements attached by lithography, for example as disclosed in self-pending patent application 09/023859 filed February 13, 1998, are columnar elements. Used in place of 104. Additional illustrations of suitable microelectronic spring contacts for use in the present invention and methods for manufacturing such contacts were made, for example, on February 13, 1998, during self-pending. Brought by patent application 09/023859 filed, patent application 09/364788 filed 30 July 1999, patent application 09/710539 filed 9 November 2000, All of these patent applications are hereby incorporated by reference in their entirety.

  Each of the earlier patent applications describes a microelectronic spring structure by depositing a resilient material (such as by electroplating) on or within the sacrificial layer on the substrate and then removing the sacrificial layer. And a resulting spring structure is disclosed. The sacrificial layer is slanted or contoured that extends upwards or away from the substrate, such as by attaching the mold to the molding (plastic) layer using a special molding tool to form the mold. Is shaped to have an open area. Alternatively or additionally, the sacrificial layer is patterned to provide an opening that exposes the underlying substrate. A seed layer is deposited over the sacrificial layer and / or the exposed areas of the substrate and patterned into the planar shape of the desired spring structure or spring component. Further, a resilient layer is plated on the seed layer. The sacrificial layer is removed, leaving the beam and / or tip, post components that are then assembled to provide a structure similar to structure 100. In some embodiments, assembly is not required for the deposition / patterning step to provide a spring structure with a bottom portion attached to the substrate and a contoured and / or tilted beam extending from the bottom portion. . However, each of the previous structures includes a contact tip that is precisely formed utilizing a patterned masking / etching process and assembled into a spring contact structure. Thus, the present invention is easily adapted to use with each of the previous structures and methods, and easily to some other structure that provides similar conditions for the precise formation of contact tips for microelectronic contactor structures. Fits.

  Referring to FIG. 1, the microelectronic contactor structure 100 consists of a beam 102 having an upper surface 108 that functions as a reference surface for mounting a tip structure 110. In order to achieve the strict planarity of the surface 108, the beam 102 can be made of a resilient material, for example, on a sacrificial layer or substrate as described in the above-referenced patent application 09/023859, for example It is preferable to form it by making it adhere. In the present invention, a “sacrificial layer” refers to a photoresist-like material that is deposited on a substrate and later removed from the substrate while forming a desired component or structure, such as a microelectronic spring contact element. means. By “sacrificial substrate” is meant a substrate that is attached to a desired component or structure, such as a microelectronic spring component, and later removed from that component or structure during its formation. As long as the structure 100 provides a contact plane 114 and / or a reference plane 108 for mounting the tip structure 110, the remaining details of the structure 100 can be configured in a variety of different ways. For purposes of illustrating exemplary applications of the present invention, other details of structure 100 are disclosed below, but it is clear that the present invention is not limited thereby.

  Beam 102 of structure 100 is secured to substrate 106 by columnar elements 104. The substrate 106 comprises a contactor for a semiconductor device such as a semiconductor wafer. Such a contactor comprises a specially shaped slab made of a ceramic material having opposing main surface terminals and electrical internal traces connecting each terminal on the first surface and the corresponding terminal on the second surface. Often included. Alternatively, the substrate 106 includes a probe card or other printed circuit board, or a semiconductor device such as a silicon chip or wafer, or some other electronic component such as a ceramic material or electrical connector. Sometimes. The columnar element 104 is typically a terminal (see FIG. 10) that is further connected to a circuit element of an electronic component such as, for example, an interconnect substrate or an interposer substrate, or a semiconductor wafer or die, or a product or test interconnect socket. (Not shown), or attached to a ceramic or plastic semiconductor package or chip carrier.

  Contact tip 114 is attached to surface 108 of beam 102. In one embodiment of the present invention, the contact tip 114 is attached to a pad 112 that is further mounted on the surface 108. Both the contact tip 114 and the pad 112 include a tip structure 110. The tip structure 110 further includes an alignment target 116. The pad 112 is used to lift the contact tip 114 above the top surface 108 of the beam 102 so that the contact tip contacts the surface of the matching electronic component prior to any other part of the structure 100. . In an alternative embodiment, if the beam 102 is tilted away from the columnar element 104 and the substrate 106, the pad 112 is omitted and the contact tip 114 and alignment target 116 are attached directly to the surface 108. In either case, the contact tip 114 and the alignment target 116 are formed on the sacrificial substrate and attached together to the beam 102, and thus a position relating to aligning at least as accurately as possible with respect to the contact tip itself. The precise positioning of the alignment target relative to the contact tip necessary to provide alignment is provided.

  FIG. 2A is a side view of structure 100. The contact tip 114 is on the pad 112 toward the columnar element 104 (ie, toward the fixed base of the beam 102) relative to the alignment target 106 located towards the free end of the beam 102. It is preferable that they are arranged. This positional relationship is due to the tendency for debris to be pushed toward the fixed end (base) of beam 102 when tip 114 is pressed against a matching terminal, so that debris accumulates on the alignment target. To help prevent it. Also, by positioning the alignment target towards the free end of the beam, the alignment target and the free end of the beam tend to be pushed further away from the matching substrate than the part proximate its fixed base. Preventing unintentional contact between conforming substrates is encouraged. Contact with a compatible substrate makes the target invisible or debris and is therefore usually undesirable. However, for some applications, there may not be enough space to place the alignment target toward the free end (distal end) of beam 102. In other cases, the beams are configured differently, such that the position proximate the distal end is disadvantageous for other reasons. For such applications, the alignment target 116 is positioned proximate to the fixed base of the beam 102 as shown in the plan view of FIG. 3C.

FIG. 2B shows a side view of the tip structure 110 and illustratively shows the relative dimensions and position of the contact tip 114 and the alignment target 116 on the pad 112. Contact tip 114 may be truncated pyramid having a height “h ₁ ” and a flat surface 118 at its apex. In other embodiments of the present invention, the contact tip may be a pyramid shape with no truncated vertex, or a prism shape with or without a truncated tip, or like a hemisphere. Any other suitable shape may be used. Pyramid and prism shapes are tapered along their crystal planes so that they are tapered shapes that can provide a well-supported raised tip and pyramid or prism-shaped pits. It is usually used because it can be easily formed by etching silicon and then using the silicon pits as an electroforming mold. However, the present invention is not limited to a specific shape of the contact tip.

Similarly, because it is advantageous to form the target 116 on the same sacrificial substrate as the contact tip 114 using the same silicon etching and plating techniques, the alignment target 116 also has a prism shape or pyramid shape. can do. In order to prevent unintentional contact with matching components, the target 116 is substantially “h”, for example at a height between about one quarter and three quarters of “h ₁ ”. Preferably, it has a height “h ₂ ” lower than “ ₁ ”. The degree of difference between “h ₁ ” and “h ₂ ” is highly dependent on application requirements and spring contact geometry. For example, an alignment target located “inside” the contact tip, ie, adjacent to the fixed end of the beam as shown in FIG. 3C, can be used to prevent unintended contact with a matching component and to the alignment target. It must be relatively low so that debris does not stack. In contrast, the alignment target, located “outside” the contact tip, ie, toward the free end of the beam relative to the contact tip, as shown in FIGS. Just a minute low. Of course, whatever the relative height of the contact tip and the alignment target, it is generally preferred that the alignment target be positioned so that it does not contact a matching component, which is usually This means that the alignment target is substantially lower than the contact tip.

  As a result, as shown in FIG. 2B, the alignment target width “w” is generally narrower than the contact tip width, particularly when pyramid or prismatic features are utilized. At the same time, the target width should be at least large enough to be seen in the vision system used to align the target contactor. Thus, for example, at least one dimension of the alignment target, which is its length, may be large to provide a feature that can be analyzed more easily while keeping the target height lower than the corresponding contact tip. It is advantageous.

A prism-shaped alignment target 116, shown in plan view in FIG. 3A, illustrates such an approach. The target 116 can be contrasted with a pyramid shaped alignment target 120 shown in plan view in FIG. 3B. The targets 120 and 116 have the same width “w” and the same height “h ₁ ”, while the target 120 is square in the plan view, whereas the target 116 is an elongated rectangle in the plan view and the pad 112 The film is substantially stretched with respect to the width. In a visual system having the smallest feature size that can be analyzed approximately equal to the planar area of the target 120, the target appears as a single pixel or a small group of pixels. As such, it is difficult to distinguish from the surrounding environment including irregularities such as stacked debris or oxides. Such irregularities appear as a single pixel or an irregular collection of pixels that produces a mottled background that makes it difficult to determine the alignment target. In comparison, target 116 appears as a line of pixels that rises more in visual contrast to the surrounding environment. As shown in FIG. 3C, in one embodiment of the present invention, the alignment target 116 has a length “l ₁ ” that is shorter than the length “l ₂ ” in the width direction of the pad 112 and is thereby opened Regions exist at both ends of the alignment target 116. A line point, such as an end point or midpoint, is selected and used as a reference point.

  In another embodiment of the invention, a slab-shaped alignment feature, such as a pad, is provided on the contact structure, optionally spaced from the pad at the contact tip. An exemplary circular slab-shaped alignment pad 126 is shown in FIGS. In essence, the pad 126 is in the form of an alignment target that is manufactured at a different step in the process of forming the microelectronic contact. FIG. 4A is a side view of target 126 and the adjacent tip structure 110 on the tip portion of spring contact beam 102. FIG. 4B is a plan view of the same structure. Such slab-shaped pads that are shaped and arranged for alignment purposes are particularly useful for certain applications, for example when the height available for alignment targets is very limited. When the tip 114 is formed in a process other than the etching process / plating process, it is effective when a relatively large alignment structure is desired. The alignment pad 126 is preferably formed and attached to the beam 102 in the same process steps as the contact tip pad 112, so that accurate alignment accuracy with respect to the contact tip 114 is achieved. The alignment pad 126 is preferably separated and spaced from the pad 112 to prevent contamination from debris from the tip 114 and to have more reliable visibility. The alignment pad 126 preferably has a clear shape for more reliable visibility. A circular shape is particularly preferable because it can be easily determined to use the center of the circle as a reference point, and a relatively large circle can be easily visually recognized. However, any other shape can be used.

  5A-5E illustrate the application of the previous structure to an exemplary contactor. The contactor 130 includes a generally slab-shaped substrate 132 that is typically made of a ceramic material. As used herein, a “contact” includes a specialized apparatus for making electrical connections with a wafer-shaped semiconductor device during electrical testing of the semiconductor device. In addition, a “contact” includes any other device having a plurality of contact elements, such as, but not limited to, a microelectronic spring for making contact with some form of matching component Including contacts, where the contacts on the contactor are aligned with the appropriate components utilized in the vision system.

  As shown in FIG. 5A, a typical contactor includes a plurality of spring contacts 136, in other words, includes spring contacts arranged in a plurality of groups 138. In one embodiment of the present invention, most of the plurality of spring contacts 136 do not have an alignment target. An alignment target is provided for a number of selected spring contacts, eg, four spring contacts 134. Targeted contacts 134 are arranged so that the positions of all contacts 136 are accurately determined from the positions of the targeted contacts. For many applications, at least three or four alignment targets are required to align the contactor. However, for the purpose of surrogate functionality, additional targeted contacts 134 are provided, for example, each group 138 can be provided with targeted contacts (not shown). Obviously, the contactor 130 and the contact 136 are not drawn to scale. For more clarity, contact 136 is illustrated somewhat larger relative to contactor 130 than is typical for semiconductor wafer applications. Details of the contactor 130 and contact 136 and methods of manufacturing these components are disclosed in the references known or otherwise incorporated in the prior art.

  FIG. 5B is an enlarged view showing a group of spring contacts 138 on the contactor 130. A typical alternating arrangement 136 of spring contacts is evident, which consists of a contact tip 114 and a separate beam 102 for each spring contact 142. A post or columnar element is hidden behind the beam 102 of each spring contact. Also, a uniquely shaped pad 140 is evident. A relatively large pad, such as pad 140, may provide additional space for a larger alignment target or may itself function as an alignment target. Due to the unique shape of the pad 140, the targeted contact 134 can be easily placed. Due to the relatively large dimensions and unique shape, the pad 140 can be placed utilizing the low magnification of the vision system. Further, the magnification of the vision system is expanded to place the alignment target on the contactor 134.

  FIG. 5C shows contact 134 with targeted and adjacent contact 142 without target. The components of the contacted contact 134 and the non-targeted contact 142 are more apparent in this enlarged view. The pads 112 and contact tips 114 of each contact 142 and the beam 102 are evident. Also, the tip 114 of each contact 134, the pad 140, and the alignment target 116 are clear. In addition, a free end 146 and a fixed end 148 of the contacts 142 and 134 are shown, respectively. In one embodiment of the invention, the untargeted contact 142 and the targeted contact 134 comprise the same type of beam 102 and contact tip 114. However, in alternative embodiments, the targeted contact 134 may utilize a different beam configuration and / or contact tip configuration than the untargeted contact 142. For example, in one embodiment of the invention, the structure 134 functions only as a support for the alignment target and does not have a contact tip.

  FIG. 5D shows an enlarged view of the pad 140 at the free end 146 of the beam 102. A prism-shaped alignment target 116 as described above with respect to FIGS. Alternatively, the circular portion of pad 140 is used as an alignment feature, and target 116 is omitted. Alternatively, more than one alignment target may be provided on the same pad 140, and two parallel alignment targets, such as target 116, may be provided. As shown in FIG. 5E, a cross-shaped target 144 consisting of two intersecting prisms is particularly useful for indicating a reference point at the cross intersection. Each of the aforementioned goals is formed using a lithographic masking / etching process as described below.

  FIG. 6 shows a perspective view of a sacrificial substrate 150 that is covered by a resist layer 152 during an exemplary step of the method of manufacturing an alignment target of the present invention. Typically, the substrate 150 is a silicon substrate and preferably has a flat surface extending over an area at least as large as the surface of the contactor provided with spring contacts. Other substrate materials can be utilized as long as they can provide a flat surface that is sufficiently uniform and uniformly and predictably etched below the patterned resist layer. Resist layer 152 can be any photoresist material as is known in the art. Layer 152 is patterned and has square openings 154 (showing four of many) where contact tips are desired and rectangular openings 156 (of many) where alignment targets are desired. Indicating one). It is clear that the square holes produce pyramidal pits when the underlying substrate is etched, and the rectangular holes produce prism-shaped pits. Other shapes, such as a cross shape, a conical shape, a truncated conical shape, etc., can be provided by a suitable combination of substrate and aperture shape.

  FIG. 7A is a cross-sectional view exemplarily showing a square opening 154 and a rectangular opening 156 after etching the substrate 152. In one embodiment of the invention, the etching is stopped at a point before the pyramidal pits are completely etched. In this respect, the prism-shaped pit 160 is etched excessively, but is narrower than the pit 158. Thereby, the depth of the pits 158 is mainly controlled by the time of exposure to the etching solution, while the depth of the pits 160 is mainly controlled by the relative dimensions of the openings 156. After the pit 160 is etched at the end of the opening 156, further etching (“excessive etching”) must proceed more slowly than the etching of the adjacent pit 158. The production of adjacent pits of different and controllable depth is thus achieved.

  FIG. 7B shows the same portion of the substrate after further processing as follows. When the desired pit depth is achieved, the etching is stopped and the resist layer 152 is removed as is known in the art. Typically, a conductive seed layer and / or release layer is applied over the surface of the substrate to facilitate subsequent electroplating and release of the tip structure from the substrate 150. Preferred materials for the seed layer and / or release layer 164 are known in the prior art or described in the incorporated references. The second resist layer is applied as known in the prior art and patterned to expose the tip structure and the pad-shaped opening 166 for electroplating the support pad against the alignment target. FIG. 7B shows a single opening positioned over both pits 158 and 156. However, if desired, two separate openings (one located above each pit 156, 158) can be provided for separately formed pads. Further, for example, in the embodiment in which the alignment target is formed in a pad shape and the rising alignment target is formed, the pit 156 is omitted.

  Further, pad-shaped openings 166 are filled with one or more metal layers 168, 170, such as by electroplating, resulting in a filled opening as shown in FIG. 7C. The construction of the layers 168, 170 is known in the prior art. Any number or configuration of layers can be utilized and thus the invention is not limited. Further, the exposed surface 172 of the top layer 170 is planarized, such as by chemical mechanical polishing, and the second resist layer 162 is removed, and the pad 112 and contact tip 114 as shown in FIG. 7D and described above. A tip structure 110 consisting of the alignment target 116 appears. There are several similar tip structures, eg, something with an alignment target such as target 116, only one of the contact tip or alignment target and others, contact tip or alignment target at all Obviously, perhaps not others can be present on a substrate 150 having an exposed surface that is substantially in the same plane. Furthermore, such a tip structure is easily joined to an array of spring contacts, such as those shown in FIGS. The tip structure 110 can have a variety of shapes and is not limited to the pyramid shape discussed in the previous paragraph.

  FIG. 7E shows a cross-section of an exemplary contact structure 134 during the step of joining beam 102 to tip structure 110. A bonding material 178, such as solder paste, is accurately applied on the surface 172, as is known in the art. The substrate 150 is placed in a suitable holding fixture, and the substrate 106 with a plurality of contact structures in place on its surface is lowered downward in a parallel relationship with respect to the substrate 150, eg, contact structure 134. Each contactor structure is aligned with a corresponding tip structure, eg, structure 110. The substrate is moved together until the bonding material contacts both the tip structure 110 and the beam 102. Furthermore, the bonding material is activated, for example, by being heated, and this bonding material further pulls the tip structure and the beam together by surface tension to a relatively uniform position where the bonding material is cured (for example, by cooling). . Careful control of the surface properties of the materials to be bonded, the amount of bonding material applied per unit area, alignment of the substrates 106 and 150, curing conditions (such as temperature) are typically very much across the contactor substrate. This produces a uniform thickness of adhesive on the tip structure. It is known that the thickness of the adhesive affects the position in the z direction (direction perpendicular to the substrate 106) of the contact tip and the alignment target. The x and y directions (positions in the plane parallel to the substrate 106) are fixed by the sacrificial substrate and the patterning masking step. Thus, adjacent tip structures and alignment target locations can be defined with the required accuracy in three directions across the substrate. The alignment accuracy can be supported by comparing the measured and expected positions of selected contact tips across the substrate in relation to the primary alignment target. If the difference exceeds a certain tolerance (eg, half the pitch of the terminals of the semiconductor device), the substrate must be repaired or discarded.

  The alignment target need not be located on a contact structure that is exactly equivalent to the structure carrying the contact tip. Also, the target alignment function can be achieved by placing them on a raised platform that is configured to provide a mounting surface that is substantially flush with the surface to which the contact tip is mounted. . The raised platform is elastic or is supported so as to be substantially rigid (ie, substantially inelastic). A top view of the substantially rigid raised platform 180 adjacent to the spring contact 184 on the substrate 106 is shown in FIG. 8A. The configuration shown in FIG. 8A is desirable in applications that use the contact “microtip” 182 and corresponding small contact structure 184 for the tip structure 194. The structure 184 is too small to support the alignment targets 188, 192. Therefore, a raised platform 180 with a relatively large beam 186 is provided for attaching the alignment target. Thus, alignment targets 188 and 192 are formed on the same sacrificial substrate as the microchip 182 and transferred to the structures 180 and 184 on the substrate 106 along with the microchip. The alignment between the alignment target and the microchip is achieved in the same manner as described above.

  A cross-sectional view of platform 180 is shown in FIG. 8A, particularly with portions of tip structure 194 and contact structure 184 visible behind the platform. The pad-type alignment target 192 has a smooth surface free of raised and recessed structures. A recessed alignment target 188 is provided on the upper surface of the pad 190. The beam 186 is supported along its length by the four pillars 104 and is therefore substantially rigid with respect to the cantilever beam of the spring contact 184.

  If the alignment target is large relative to the contact tip, it may be preferable to use a pad-type target such as target 192 or a recessed target such as target 188. Raised alignment targets are not well suited for such applications due to the small spacing provided by the contact tips. Furthermore, the contact tip, such as a microtip, is sufficient in the vertical direction even when the alignment target is not lifted, for example, the target 188 below the surface of the pad 190 and / or the pad-type target 192. No gaps. Therefore, as shown in FIG. 8B, it is further desirable to have a pad and pad type target for the alignment target recessed below the base of the microchip. At the same time, however, the alignment targets and / or their pads are preferably formed on the same sacrificial substrate as the microchip for the purpose of maintaining accurate alignment between the target and the tip. In order to achieve the desired structure on the same sacrificial substrate, a series of manufacturing steps different from those described above are utilized.

  9A-9F are cross-sectional views of a substrate and material laminated on the substrate during an exemplary sequence of steps for forming a relatively large alignment target adjacent to a microchip. . The sacrificial substrate 200 is silicon or other etchable material as described above. A first resist layer 202 is deposited and patterned to expose most of the substrate 200 except directly above where any recessed alignment targets are to be formed. Further, the substrate 200 is etched to provide a protrusion below the remaining area of the resist 202. The shape of the protrusion depends on the etching characteristics of the substrate 200, the etching method used, and the shape of the resist region 202. For example, underetching a rectangular resist region on a crystalline silicon substrate results in a prefix prism shaped protrusion. An exemplary cross-sectional view of two such protrusions 204 is shown in FIG. 9A.

  Further, the first resist layer 202 is removed and a second resist layer 206 is applied and patterned to expose a pad-shaped opening, such as opening 208, where the tip structure is to be formed. . The substrate is again etched, resulting in a plurality of pad-shaped recesses, such as recess 209 shown in FIG. 9B.

  The second resist layer is then removed and a third resist layer 210 is applied and patterned to provide a plurality of small openings, such as openings 212, where contact tips are to be formed. The substrate 200 is etched again to form a plurality of pyramidal pits such as pits 214 shown in FIG. 9C.

  Further, the third resist layer is removed and a seed / release layer (not shown) is applied. A fourth resist layer (not shown) is applied to the substrate 200 and patterned to provide a pad-shaped opening over the protrusions 204 and pits 214, as described above in connection with FIG. 7B. Attached. Further, the substrate is plated with one or more metal layers, the openings are substantially filled, and the exposed plated areas are planarized as described above in connection with FIG. 7C. The fourth resist layer is removed, revealing a plurality of tip structures 194 and recessed alignment targets 188 in the pad 190, as shown in FIG. 9D. The tip structure and pad have a mounting plane 216 that is flattened to be suitable for connecting to a plurality of contact structures, similar to that described above in connection with FIG. 7E. Thus, a structure similar to that shown in FIGS.

  It is also clear that alignment targets can be added to the tip structure after it has been manufactured, for example by further selective etching or laser marking. Although it is generally preferred to form the alignment target in the same lithography step as the contact tip, this is not always possible. For example, in some cases, it may be desirable to add an alignment target to a contactor manufactured without providing an alignment target. The following example illustrates a method for adding an alignment target in a later step.

  Referring to FIG. 10A, the pad 300 of the tip structure 312 includes a contact tip 314 that can be manufactured, for example, by one of the processes described above. Optionally, the structure 312 can be attached to a beam 302 of a spring structure. The target area 304 is provided where the alignment target is to be placed. In FIG. 10B, the laser alignment system 324 can be aligned by directing the low power beam 326 to the contact tip 314 and offset a predetermined distance to the target position 320. In addition, the laser 324 is fired to emit a high power beam 328 sufficient to produce a well defined target 316 (see FIG. 10C). The target position 316 (laser beam target) is, for example, offset by x and y in the direction shown, and shifted by a predetermined spatial distance. In addition, the offset includes an offset in the z direction (not shown). As shown in FIG. 10C, the target 316 is defined at the center of the target of the laser beam. A contactor that uses a later formed target such as the target 316 as a reference point can also be aligned. According to a further exemplary manner, direct deposition of target 316 is achieved utilizing vapor phase organometallic precursor and ion beam direct writing. Contact tip 314 is targeted, and ion beam assisted metal deposition is utilized to produce a target 316 feature that is defined to be offset away from the contact tip.

  In some embodiments of the present invention, the relative position (s) of the contact tips are measured and recorded in a data file or database. This data can be obtained from the design process or measured directly after manufacture by optical or other measurement methods. Such data is for contactors with multiple contacts and alignment targets where the offset between the contact tip of the contactor and the alignment target varies somewhat from contact to contact across the contactor. Is particularly useful. Such changes are more likely to occur if, for example, the alignment target is formed by a laser, and the alignment target is not formed in the same lithography step as the contact tip. In order to obtain such data, a single point, such as a tip at the contact tip on the contactor, is preferably selected as the reference point. Sometimes, all of the contact tips are substantially fixed relative to the reference point, but it may also be desirable to measure the position of the contact tips for accurate positioning. The position of each alignment target with respect to one or more adjacent contact tips is further measured. From the measured offset, the coordinates of the alignment target with respect to a fixed reference point are defined regardless of any change in the offset distance. In addition, coordinate data is input into the test system used to align and position the contact tip for the test operation, thus optimal alignment between the contactor and the device or wafer being tested. Is achieved.

  A method for aligning and contacting a corresponding array of microelectronic contactor elements using an alignment target is illustrated below. The array consists of a first array and a second array, the purpose being to achieve contact between corresponding contact elements of the first array and corresponding contact elements of the second array. The first array of contact elements includes a plurality of contact tips and a plurality of alignment features that are substantially fixed relative to the first array. As described above, each selected one of the first array of contact elements further comprises an alignment feature spaced from the contact tip. The first array consists of probe card contact elements and the second array consists of wafer contact elements, but the invention is not limited thereby.

  As a first step, the method defines a plurality of alignment feature coordinates for a selected one of the plurality of contact tips of the first array. This is accomplished by direct measurement or based on known relationships between elements formed using a patterning-masking / etching process. The second array is kept in a known position, such as by being held on a wafer chuck attached to the frame of the test system. The first array is mounted on a corresponding movable test head of the test system. When the array is mounted on a suitable test system, the position of the first array with respect to the second array uses the coordinates to transform the measured position of multiple alignment features with respect to the second array. Defined by That is, the position of the contact tip of the first array is defined by measuring the position of the alignment feature and applying an appropriate correction based on the coordinate data. Further, the first array is positioned relative to the second array based on its defined position until contact is achieved between the second array and the corresponding contact element of the first array. . The position of the contact tip is repeatedly defined as desired during the alignment process. By utilizing this method, the contact tip can be moved to the corresponding pad or other array in the second array without any need to find or measure the location of the contact tip itself during the testing process. It can be arranged in exact contact with the contact element.

  Thus, while a preferred embodiment of a reference alignment target on a microelectronic contact has been disclosed, it will be apparent to those skilled in the art that certain advantages within the scope of the system are achieved. It will be apparent that various modifications, applications and alternative embodiments may be implemented within the scope and spirit of the invention. For example, although a reference alignment target on or adjacent to a pad having a contact tip has been illustrated, the inventive concept described above can be applied to an array of contacts in the same manufacturing steps as the contact tips of the array. Clearly, it applies equally to any reference target that is attached (or formed on an array of contacts). Furthermore, the idea of the invention is that the alignment target arranged in another type of microelectronic contact different from that shown here in alignment or measurement with respect to the contact tip located in the same place. It can also be applied to. For example, the alignment target is placed on a contact element or thin film probe card that is not inherently resilient, such as a buckling type probe. Similarly, the method of aligning an array of contact elements utilizing alignment targets on at least one array of contact elements is not limited to utilizing a particular type of contactor or device. Rather, the method is utilized with any array of contact elements in which alignment targets or features can be placed in alignment or measurement with respect to the tips or points of the contact elements. The invention is further defined by the appended claims.

Claims (30)

A contactor for contacting a semiconductor device,
A plurality of contact structures arranged on a substrate and presenting a plurality of contact tips, each of the plurality of contact structures contacting a terminal of the semiconductor device;
A contactor comprising: means for aligning terminals of the semiconductor device and each of the plurality of contact tips;   The means for aligning includes a plurality of alignment targets, the plurality of alignment targets being on at least a selected number of the plurality of microelectronic contactor structures; and The contactor according to claim 1, wherein the contactor is spaced from the tips of the plurality of contacts. A contactor for contacting a wafer-shaped semiconductor device,
A plurality of contacts disposed on the substrate and presenting a plurality of contact tips, the plurality of contact tips having their distal ends in a plane substantially parallel to the substantially flat surface. Having a plurality of contacts;
And a plurality of alignment targets disposed on the contactor substantially below a plane in which a distal end of the contact tip is disposed.   At least some of the plurality of contacts further include a tip structure, the tip structure being a pad, a contact tip attached to the pad, and the pad attached to the pad. The contactor of claim 3, comprising at least one of a plurality of alignment targets.   The contactor of claim 4, wherein at least one of the plurality of alignment targets is recessed below a surface of the pad.   The contactor of claim 4, wherein at least one of the plurality of alignment targets is raised above a surface of the pad.   At least some of the plurality of contacts further include a tip structure, the tip structure including a first pad, a contact tip attached to the first pad, and the first contact. 4. The contactor of claim 3, comprising a second pad that is substantially coplanar with the one pad, the second pad comprising at least one of the plurality of alignment targets.   The plurality of raised platforms disposed on a surface of the substrate, each of the plurality of raised platforms including at least one of the plurality of alignment targets attached thereto. 3. The contactor according to 3.   9. Each of the plurality of raised platforms further includes a pad attached thereto, and at least one of the plurality of alignment targets is recessed below the surface of the pad. Contactor. A method of forming a contactor having a plurality of microelectronic contacts and a plurality of alignment targets,
Providing a contactor substrate having a plurality of microelectronic contacts;
Forming the plurality of contact tips and the plurality of alignment targets on a sacrificial substrate;
Transferring the plurality of contact tips and the plurality of alignment targets to the plurality of microelectronic contacts;
Removing the sacrificial substrate after the transferring step.   Etching the sacrificial substrate through a patterned resist layer, forming a recess in the sacrificial substrate, and depositing material in the recess, thereby providing the plurality of contact tips and the plurality of alignment targets. The method of claim 10, further comprising forming.   Forming a plurality of pads by depositing material in a plurality of openings in the patterned sacrificial layer on the sacrificial substrate, wherein one of the plurality of pads includes the plurality of contacts; 12. The device of claim 11, attached to each of a tip and attached to each of the plurality of alignment targets, each of the plurality of openings being positioned over at least one of the recesses. Method.   The step of forming further comprises forming the plurality of contact tips by etching the sacrificial substrate through a patterned resist layer to form a plurality of recesses. the method of.   After the forming step, a sacrificial layer is deposited on the sacrificial substrate, and the sacrificial layer is patterned to define a plurality of first openings respectively disposed above the plurality of recesses, The method of claim 13, further comprising depositing material in a plurality of first openings to form a plurality of pads each attached to one of the plurality of contact tips.   The sacrificial layer is patterned to define a plurality of second openings, and material is deposited in the plurality of second openings to be adjacent to and spaced from the plurality of pads. The method of claim 14, further comprising forming the plurality of alignment targets being configured, wherein the plurality of alignment targets have a thickness substantially equal to the plurality of pads.   Defining at least one of each of the plurality of second openings on at least one of the plurality of recesses on the sacrificial substrate, thereby defining at least one recess on the substrate; The method of claim 15, further comprising providing at least a selected number of the plurality of alignment targets.   A resist layer is deposited on the sacrificial substrate, the resist layer is removed except where a plurality of protrusions are formed, the sacrificial substrate is etched to form the plurality of protrusions, and the resist layer is formed. The method of claim 16, further comprising forming the plurality of protrusions prior to forming the plurality of contact tips by removing. A method of forming a microelectronic contactor structure including a plurality of alignment targets and a plurality of contact tips,
Forming a microelectronic contactor structure including a contactor tip attached to the support structure;
Forming an alignment target on the support structure at a defined offset distance from the contact tip.   The method of claim 18, wherein the second forming step further comprises forming the alignment target using a laser.   The method of claim 18, wherein the second forming step further comprises forming the alignment target utilizing ion beam assisted metal deposition.   The method of claim 18, further comprising recording coordinates of the defined offset distance relative to the contact tip.   19. The first forming step further comprises forming the contact tip on a sacrificial substrate, transferring the contact tip to the support structure, and removing the sacrificial substrate after the transfer. the method of.   19. The second forming step includes the steps of further forming the alignment target on a sacrificial substrate, transferring the alignment target to the support structure, and removing the sacrificial substrate after the transfer. the method of.   24. The method of claim 23, wherein the first forming step further comprises forming the contact tip on a sacrificial substrate, transferring the contact tip to the support structure, and removing the sacrificial substrate after the transfer. the method of. A plurality of corresponding contact elements of the first array by aligning and connecting corresponding arrays of the plurality of microelectronic contact elements including the first array and the second array; A method of achieving a connection between corresponding contact elements of the second array, wherein the contact elements of the first array include a plurality of contact tips and a plurality of alignments. Each selected some of the plurality of contact elements of the first array further includes an alignment feature spaced from the contact tip;
The method
Determining coordinates of the plurality of alignment features for a selected number of the plurality of contact tips of the first array;
Maintaining the second array in a known position;
Determining a predetermined position of the first array relative to the second array by transferring the measured position of the plurality of alignment features relative to the second array utilizing the coordinates; When,
Utilizing the predetermined position to position the first array relative to the second array, a corresponding plurality of contact elements of the first array and a corresponding plurality of second array Achieving contact with the contact element.   26. The method of claim 25, further comprising generating a data file of the coordinates and providing the data file to an automated equipment system for aligning the first array with the second array.   26. The method of claim 25, further comprising measuring a measurement position of the plurality of alignment features utilizing a machine vision system.   26. The method of claim 25, further comprising the step of continuously repeating the second determining step during the positioning step.   26. The plurality of contact tips of the first array are substantially fixed relative to the first array during the first determining step and the second determining step. The method described in 1. A method of aligning an array of contact elements on a contactor with a corresponding plurality of contact elements on a device comprising:
Forming an alignment feature on at least one of said plurality of contact elements on said contactor, said alignment feature comprising said at least one contact of said plurality of contact elements A step disposed at a distance from the child tip; and
Determining the position of the alignment feature relative to the contact tip;
Utilizing the position of the alignment feature to align the contactor with the device.

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