TWI656583B - Patterned liners used to create virtual solder masks in wafer level wafer size packages - Google Patents

Abstract

The method and apparatus for creating a patterned pad of a virtual solder mask in a wafer-level chip size package may include a contact pad formed on a semiconductor die, the contact pad including: a central pad, a line, a central pad The first set of spokes extending from the pad. The bracket may surround a portion of the first spoke pattern and the center pad. Solder balls may be formed on the center pad and the first spoke pattern but not on the bracket. The center pad may include a circular metal dish or ring. A second spoke pattern including one or more spokes may extend from the bracket. The second bracket may surround the first and second spoke patterns, the bracket, and the center pad. The first and second spoke patterns may have different widths, and may extend at different angles with respect to the center pad.

Description

Patterned pads used to create virtual solder masks in wafer-level chip-scale packages

Some specific aspects of the present disclosure relate to semiconductor chip packaging. More specifically, some specific aspects of the present disclosure relate to methods and systems for creating patterned pads for virtual solder masks in wafer-level chip scale packages.

Semiconductor packages protect integrated circuits or chips from physical damage and external stress. In addition, it can provide a heat conduction path to efficiently remove the heat generated in the wafer, and for example, also provide electrical connection to other components such as a printed circuit board. Materials used for semiconductor packaging typically include ceramic or plastic, and the form factor has progressed from ceramic flat packaging and dual in-line packaging to pin grid arrays and leadless chip carrier packaging, among others.

By comparing the present disclosure listed in the rest of the case by using traditional practices and reference drawings, those skilled in the art will understand further limitations and disadvantages of such a system.

An aspect of the present invention is a method of semiconductor packaging, which includes providing a contact pad on a semiconductor die, the contact pad including: a center pad; a line; and a first spoke pattern including a liner from the center One or more spokes extending from the pad.

Another aspect of the invention is an electronic device including a semiconductor crystal A contact pad on the grain, the contact pad including: a central pad; a line; and a first spoke pattern including one or more spokes extending from the central pad.

100‧‧‧Electrical interconnection

101‧‧‧Metal Contact

103‧‧‧Semiconductor die

105A, 105B‧‧‧contact pad

107‧‧‧ Line

109‧‧‧Molding compound

111‧‧‧Crack

200‧‧‧Electrical interconnection

201‧‧‧Solder ball, metal contact

205‧‧‧patterned liner

205A‧‧‧Central pad

205B‧‧‧Spoke

205C‧‧‧Bracket

207‧‧‧ Line

303‧‧‧spoke

305‧‧‧Central pad

307‧‧‧ Line

309‧‧‧Bracket

400‧‧‧patterned contact pad

405A‧‧‧Central pad

405B‧‧‧Spoke

405C‧‧‧Bracket

407‧‧‧ Line

500‧‧‧patterned contact pad

507‧‧‧ Line

513‧‧‧Outer bracket

515‧‧‧External spoke line

517‧‧‧Inner bracket

519‧‧‧First inner spoke

521‧‧‧Second inner bracket

523‧‧‧Second inner spoke

525‧‧‧Open pad core

600‧‧‧patterned contact pad

603A、603B‧‧‧Trench

605A, 605B ‧‧‧ (virtual) pad

607A, 607B‧‧‧ line

610‧‧‧patterned contact pad

905A, 905B, 905C ‧‧‧ center pad, inner pad

907A, 907B, 907C ‧‧‧ spokes

909A, 909B, 909C‧‧‧ (outside) bracket

h1, h2‧‧‧thickness

FIGS. 1A-1D illustrate various views of interconnects formed in a molded chip-scale package according to the exemplary embodiments of the present disclosure.

2A-2B demonstrate electrical interconnections with patterned pads according to exemplary embodiments of the present disclosure.

3A~3H illustrate various patterned contact pads according to exemplary embodiments of the present disclosure.

4A and 4B demonstrate a top view and an oblique view of a patterned contact pad showing current dispersion according to an exemplary embodiment of the present disclosure.

FIG. 5 illustrates another exemplary structure for current dispersion in a patterned contact pad according to the exemplary embodiment of the present disclosure.

FIGS. 6A and 6B demonstrate patterned contact pads utilizing cut-outs according to exemplary embodiments of the present disclosure.

7A-7H demonstrate further examples of patterned contact pads according to exemplary specific aspects of the present disclosure.

8A-8G illustrate further examples of contact pad current dispersion according to the exemplary embodiment of the present disclosure.

9A-9C illustrate a patterned contact pad with rotor spokes according to an exemplary embodiment of the present disclosure.

Certain aspects of the present disclosure can be found in patterned pads used to create virtual solder masks in wafer-level chip scale packages. Exemplary aspects of the present disclosure may include a contact pad formed on the semiconductor die, the contact pad including: a center pad; a first spoke pattern that extends from the center pad; and a bracket that surrounds at least a portion The first spoke pattern and the center liner. The solder balls may be formed on the center pad and the first spoke pattern, but need not be formed on the bracket. The center pad may include a circular metal dish or metal ring. The second spoke pattern may extend from the bracket. The second bracket may surround at least part of the second spoke pattern, the bracket, the first spoke pattern, and the center pad. The first and second spoke patterns may have different widths. The first and second spoke patterns may extend at different angles with respect to the central pad. The line may be electrically coupled to the contact pad. The contact pad and at least part of the solder balls can be encapsulated using an encapsulant. The first spoke pattern may extend from the center pad to have a rotor shape.

FIGS. 1A-1D illustrate various views of interconnects formed in a molded chip-scale package according to the exemplary embodiments of the present disclosure. Referring to FIG. 1A, a cross-sectional view of the electrical interconnect 100 is shown, which includes metal contacts 101, contact pads 105A and 105B, wiring 107, and molding compound 109.

The metal contacts 101 may be formed on the contact pads 105A coupled to the wiring 107, and may include, for example, solder balls, copper pillars, or other electrical contacts, which may provide electrical connections to the contact pads 105B on the semiconductor die 103. As shown by the thicknesses h1 and h2 of the molding compound 109 on each side of the metal contact 101, it is noted that the thickness h2 is greater than the thickness h1 due to at least the height of the wiring 107.

The molding compound 109 around the metal contact 101 with an increased thickness at a distance from the line 107 can cause a lateral force on the metal contact 101 during thermal cycling, which can result in The tilting movement indicated by the tilting arrow shown in FIG. 1A, and the tilting direction can be determined by the thermal expansion or cooling contraction of the molding compound 109. For example, this tilting movement may cause a crack 111 near the interface between the metal contact 101 and the contact pad 105A and/or the wiring 107. Cracks in any conductive structure formed in the electrical interconnect 100 may cause a break or reduce the reliability of the electrical connection between the metal contact 101 on the semiconductor die 103 and the contact pad 105B.

FIG. 1B is a cross-sectional view of the metal contact 101, which is shown to be transparent in the molding compound 109 and bonded to the contact pad 105A. Although the contact pad 105A is shown as a circle, it may include any of a variety of shapes, such as square, rectangular, oval, and so on. FIG. 1C is an oblique view of the metal contact 101, which is again shown transparent to show the underlying structure, and the metal contact 101 stays on the entire top surface of the contact pad 105A. The contact pad 105A is visible, and the line 107 extends from the contact pad 105A.

FIG. 1D is an enlarged view of the wiring 107 extending from the contact pad 105A, and the metal contact 101 (which is shown transparent to show the underlying structure) covers the entire surface of the contact pad 105A. This structure allows the solder balls to cover the entire surface of the contact pad 105A and the line 107 extends from one side of the surface of the contact pad 105A, which can cause a tilting movement on the metal contact 101, as described above.

2A and 2B illustrate electrical interconnects with patterned pads according to exemplary embodiments of the present disclosure. Referring to FIG. 2A, an oblique view of the electrical interconnect 200 is shown, which includes solder balls 201, patterned pads 205, and wires 207. The metal contact 201 and the wiring 207 may be substantially similar to the metal contact 101 and the wiring 107 described in relation to FIGS. 1A to 1D. FIG. 2B shows a top view of electrical interconnect 200 in which metal contacts 201 are shown to be mostly transparent to show the underlying structure of patterned pad 205. The patterned pad 205 may include a central pad 205A, a spoke 205B, a bracket 205C, which The center center pad 205A may include a metal pad having a spoke 205B extending outward to the bracket 205C, and may at least partially surround the center pad 205A. Although the metal liner 205A is shown as a circle, it may be, for example, other shapes, such as square, rectangular, or oval. The structure of the patterned pad 205 allows the radial pattern 205B to be placed symmetrically around the central pad 205A, which allows the solder of the metal contact 201 to cover only part of the patterned pad 205 without the need for a defined mask opening . Incidentally, due to the symmetry of the spoke 205B around the center pad 205A, no net tilting force can be applied to the metal contact 201.

The spoke pattern 205B and/or the bracket 205C can also improve the adhesion and conductivity formed on the patterned pad 205 for the interconnection of the metal contacts 201, wherein the bracket 205C can allow the current to pass through each spoke 205B Evenly distributed, this can alleviate the electromigration concerns of traces close to the contact pads. The above-mentioned benefits can be achieved regardless of whether the patterned pad 205 and/or the metal contacts 201 are to be at least partially encapsulated by the molding compound or other materials in the same or other specific aspects.

3A~3H illustrate various patterned contact pads according to exemplary embodiments of the present disclosure. 3A~3H may include changes in the structure or method shown in FIG. 2. 3A~3C represent the number of varying spokes 303 and the bracket 309 surrounds the spokes 303, while FIGS. 3D and 3E demonstrate different numbers of spokes 303 but no brackets. The structure illustrated in FIG. 3H has a single spoke 303 and a line 307 on opposite sides of the center pad, or two spokes if the line is regarded as a spoke. FIGS. 3F and 3G show a modified stent pattern in which the spokes 303 can be oriented symmetrically around the central pad 305, but the intermittent or partial stent 309 need not completely surround the central pad 305. The pattern design for the special liner can be constructed based on, for example, the magnitude of current, desired current dispersion, characteristic size, or metal conductivity.

FIGS. 4A and 4B illustrate a top view and an oblique view of two similarly patterned contact pads according to an exemplary embodiment of the present disclosure, which exhibit current dispersion. Referring to FIG. 4A, a top view of the patterned contact pad 400 is shown, which includes a central pad 405A, spokes 405B, and a bracket 405C, and the line 407 is coupled to the patterned contact pad 400.

4A is a top view of a patterned contact pad 400, which demonstrates the current dispersion capability of the spoke pattern, in which the input current (as indicated by the arrow pointing into the line 407) can be more evenly distributed to each spoke via the bracket 405C Line 405B, as shown by the curved arrow. The bracket 405C around the pad 405A can distribute current to completely surround the central pad 405A, and thus can ease electromigration, which can cause defects in the metal to migrate over time due to current passing through or near the defects or Swell.

FIG. 4B illustrates an oblique view of the metal contact 201 on the electrical interconnect 200, which may be substantially similar to the patterned contact pad 400, but with more spokes. Because the spokes are arranged symmetrically around the metal contacts 201, changing the molding thickness when formed on the spokes may not cause a net tilting force. Incidentally, multiple conductive paths can provide the current spreading ability around the metal contact 201, so that the current is more evenly distributed around the pad, such as not entering or leaving from a single position of the metal contact 201, thereby alleviating the defects Electromigration.

FIG. 5 illustrates another exemplary structure for distributing current around the patterned contact pad according to the exemplary embodiment of the present disclosure. Referring to FIG. 5, a patterned contact pad 500 and a line 507 are shown. The patterned contact pad 500 may include an outer bracket 513, an outer spoke 515, a first inner bracket 517, a first inner spoke 519, a second inner bracket 521, a second inner spoke 523, and/or an open pad core 525 .

In addition to using the added spokes around the original pad to distribute the current, the pad itself It can also be divided into radial lines toward the center of the patterned pad, which can allow the current path to be redistributed. The patterned contact pad 500 exemplifies the current distribution brought inwards toward the center of the pad, and the current path is in multiple directions and has a different radial distance from the center of the patterned contact pad 500. The open pad core 525 is "open" meaning that in this exemplary embodiment, the core pad includes a ring rather than a solid circular pad.

6A and 6B demonstrate patterned contact pads that utilize trenches according to exemplary embodiments of the present disclosure. Referring to FIG. 6A, a patterned contact pad 600 and a line 607A are shown. The patterned contact pad 600 may include a pad 605A and a trench 603A, where the trench 603A may include a metal region that forms a line 607A and/or the patterned contact pad 600 has been removed or omitted into a pattern, which is In this example, a semi-circular leading edge facing the pad 605A is created.

Therefore, the configuration of the groove 603A can define the liner 605A, as indicated by the dotted circle, it can minimize the impact on the routing, that is, it is not necessary to define the spokes, brackets or other features to completely surround the liner The pad avoids taking up too much die space, while increasing the reliability of the pad.

FIG. 6B exemplifies patterned contact pad 610 and line 607B. Just like the patterned contact pad 600, the dummy pad 605B may be defined by the groove 603B formed symmetrically on the opposite side of the patterned contact pad 610.

The trenches 603A and 603B may be filled with an insulating material, for example, solder support or oxide. In other examples, if the component is molded from above, the trenches 603A and/or 603B may remain empty to be filled later by the molding compound.

7A-7H demonstrate further examples of patterned contact pads according to exemplary specific aspects of the present disclosure. See Figures 7A~7H, which show changes in the patterned contact pads The number of spokes and/or the varying spoke width or thickness. Thickness in this context may refer to the width of the spoke in the x-y plane of contact and/or in the z direction coming out of the drawing plane. For example, FIGS. 7A and 7B respectively demonstrate a 4-spoke design, with varying widths in the x-y plane. Similar changes in the design of 6, 8, and 10 spokes are shown in Figures 7C~7H. The number and width of the spokes can for example be constructed based on the maximum current to be transferred via the contact.

8A-8G illustrate further examples of contact pad current dispersion according to the exemplary embodiment of the present disclosure. 8A~8G, there are internal spokes of varying thickness, internal spokes of varying configuration, central pads of varying configuration, different numbers and configurations of brackets, etc.

For example, FIG. 8A shows a solid central liner design, FIG. 8B shows an increase in the thickness of the diagonal spoke, FIG. 8C shows an increase in the width of the vertical and horizontal inner spokes, and FIG. 8D shows an increase in the angle between the diagonal and vertical/horizontal. The width of the spoke. Figure 8E shows a roughly uniform spoke width, Figure 8F shows an increase in the diameter of the solid pad core, and Figure 8G shows a wider beveled spoke line and an increase in the diameter of the solid pad core.

The patterned pads shown in FIGS. 8A-8G and FIGS. 7A-7H include a unique design solution that allows solder to cover only a portion of the pad without undefined openings (eg, solder mask openings). By adjusting the characteristic width, length, and connectivity of this patterned structure, the structure introduces new and unique design spaces to deal with various structural reliability concerns, such as circuit cracking and electromigration.

9A-9C illustrate a patterned contact pad with rotor spokes according to an exemplary embodiment of the present disclosure. Referring to FIG. 9A, a rotor structure is shown in which the spoke 907A can extend into a curved path from the center pad 905A outward to the bracket 909A. 9B shows an exemplary rotor structure, in which the spoke 907B extends vertically from the outer edge of the inner pad 905B, and then takes a curved path Diameter to the outer bracket 909B. FIG. 9C exemplifies a structure similar to FIG. 9B, but the spoke 907C takes a beveled path and extends from a portion perpendicular to the center pad 905C.

The rotor-spoke structure can reduce the distance between the inner pads 905A~905C and the outer brackets 909A~909C without reducing the length of the spokes 907A~907C and without increasing the spacing between adjacent patterned pads.

In a specific aspect of the present disclosure, a method and system for creating a patterned pad for a virtual solder mask in a wafer-level chip scale package is disclosed. In this regard, various aspects of the present disclosure may include contact pads formed on the semiconductor die, the contact pads including: a center pad; a first spoke pattern including one or more extending from the center pad More spokes; and a bracket that surrounds the first spoke pattern and the center pad. Solder balls may be formed on the center pad and the first spoke pattern but not on the bracket. The center pad may include a circular metal dish or metal ring. A second spoke pattern including one or more spokes may extend from the bracket.

The second bracket may surround the second spoke pattern, the bracket, the first spoke pattern, and the center pad. The first and second spoke patterns may have different widths. The first and second spoke patterns may extend at different angles with respect to the central pad. The line may be electrically coupled to the contact pad. The contact pad and at least part of the solder balls can be encapsulated using an encapsulant. The first spoke pattern may extend from the center pad to have a rotor shape.

Although the present disclosure has been described with reference to specific specific aspects, those skilled in the art will understand that various changes can be made and can be replaced by equivalents without departing from the scope of the present disclosure. Incidentally, many modifications can be made to adapt a particular situation or material to the teachings of this disclosure without departing from its scope. Therefore, this disclosure is not intended to be limited to the specific specific aspects disclosed, but this disclosure will include all specific aspects falling within the scope of the appended claims.

Claims (13)

A method for a semiconductor package, the method comprising: providing a contact pad electrically connected to a semiconductor die, the contact pad including: a central pad; a bracket that surrounds at least a portion of the central pad; and a first A spoke pattern including one or more spokes extending from the central pad, wherein at least one of the one or more spokes has: an inner spoke portion, which is coupled to the A central liner and covered by solder balls; and an outer spoke line portion coupled to and exposed from the inner spoke line portion, the outer spoke line portion extending through the bracket; and providing an encapsulant layer, which wraps Seal the outer spoke portion and the solder ball portion. The method according to item 1 of the patent application scope, wherein the central gasket includes a metal ring. The method according to item 1 of the patent application scope, wherein the surface of the bracket is solder-free. The method according to item 1 of the patent application scope, wherein the contact pad is on a layer that is located on the semiconductor die. An electronic device including: a contact pad electrically connected to a semiconductor die, the contact pad including: a central pad; a bracket that surrounds at least a portion of the central pad; and a first spoke pattern, which Including one or more spokes extending from the central pad, wherein: at least one of the one or more spokes has: an inner spoke portion, which is coupled to the central pad and is Solder ball coverage; and an outer spoke line portion, which is coupled to and exposed from the inner spoke line portion, the outer spoke line portion extends beyond the bracket; and an encapsulant layer, which encapsulates the outer spoke line portion And part of the solder ball. The electronic device according to item 5 of the patent application scope, wherein the central pad includes a metal ring. An electronic device according to item 5 of the patent application scope, in which a second spoke pattern including one or more spokes extends from the bracket and has at least one of the following features: the spokes of the first spoke pattern have The widths of the spokes of the second spoke pattern are different, and the first spoke pattern extends at a different angle with respect to the central pad than the second spoke pattern. The electronic device according to item 5 of the patent application scope, wherein the surface of the bracket is solder-free. The electronic device according to item 5 of the patent application scope, wherein the contact pad is on a layer that is located on the semiconductor die. An electronic device including: a contact pad electrically connected to a semiconductor die, the contact pad including: a central pad including a plurality of central spokes extending toward the center of the central pad; a first spoke pattern , Which includes one or more spokes extending from the central pad; and a bracket, which surrounds at least part of the central pad and at least part of the first spoke pattern; and an encapsulant layer, which encloses A portion of the first spoke pattern is enclosed; wherein at least one spoke of the one or more spokes extends from the central pad through the bracket. The electronic device according to item 10 of the patent application range, wherein the contact pad is on a layer that is located on the semiconductor die. An electronic device including: a contact pad electrically connected to a semiconductor die, the contact pad including: an inner bracket including a plurality of central spokes extending toward a center of the inner bracket; a first spoke pattern, which It includes one or more spokes extending from the inner bracket; and an outer bracket that surrounds at least part of the inner bracket and at least part of the first spoke pattern. The electronic device according to item 12 of the patent application scope, wherein the outer bracket includes a circuit.