Method of manufacturing semiconductor devices

Abstract

An assembly is provided including one or more semiconductor dice attached on a substrate, the semiconductor die provided with electrically-conductive stud bumps opposite the substrate. The stud bumps embedded in a molding compound molded thereon are exposed to grinding thus leveling the molding compound to expose the distal ends of the stud bumps at a surface of the molding compound. Recessed electrically-conductive lines extending over said surface of the molding compound with electrically-conductive lands over the distal ends of the stud bumps. A further molding compound is provided to cover the recessed electrically-conductive lines and surrounding the electrically-conductive lands.

Claims

1. A method, comprising: forming a first layer of molding compound on a substrate, a semiconductor die attached to the substrate, and a plurality of conductive stud bumps coupled to the semiconductor die, wherein the plurality of conductive stud bumps are embedded in the first layer of molding compound, wherein the first layer of molding compound is a laser-activatable direct structuring molding compound; leveling the first layer of molding compound to expose a distal end of a first stud bump of the plurality of conductive stud bumps at a surface of the first layer of molding compound; using a laser, forming a plurality of recesses in the first layer of molding compound to form laser ablated areas, wherein a first recess of the plurality of recesses is at the distal end of the first stud bump; forming a plurality of electrically-conductive lines at the laser ablated areas, wherein a first line of the plurality of electrically-conductive lines forms a land in the first recess and at the distal end of the first stud bump; and forming a second layer of molding compound covering at least one of the plurality of electrically-conductive lines.

2. The method of claim 1, further comprising removing the substrate.

3. The method of claim 1, wherein the substrate is one of: a tape material, a paper material, or a metallic material.

4. The method of claim 1, wherein leveling the first layer of molding compound comprises grinding the first layer of molding compound.

5. The method of claim 1, wherein the laser ablated areas form electrically conductive areas, wherein forming the plurality of electrically-conductive lines comprises plating the plurality of electrically-conductive lines.

6. The method of claim 1, wherein using the laser, forming the plurality of recesses in the first layer of molding compound to form laser ablated areas includes exposing a secondary stud bump.

7. The method of claim 1, wherein the plurality of electrically-conductive lines are formed in the plurality of recesses so that the first layer of molding compound is at side surfaces of the plurality of electrically-conductive lines.

8. The method of claim 1, wherein the second layer of molding compound includes resist material or solder mask material.

9. The method of claim 1, further comprising coupling a heat-sink layer to the semiconductor die at a side that is opposite the plurality of conductive stud bumps.

10. The method of claim 1, further comprising forming a thermally-conductive pad at the surface of the first layer of molding compound to provide a heat-dissipation path between the semiconductor die and the surface of the first layer of molding compound.

11. The method of claim 1, wherein the semiconductor die is a first semiconductor die, wherein forming the first layer of molding compound comprises forming the first layer of molding compound on and around side surfaces of a plurality of semiconductor dice attached to the substrate.

12. The method of claim 11, further comprising forming electrical lines between the semiconductor dice, wherein the electrical lines are embedded in the first layer of molding compound.

13. A method, comprising: coupling a semiconductor die to a substrate; forming a plurality of stud bumps on the semiconductor die; forming a layer of laser direct structuring compound on the semiconductor die and the plurality of stud bumps; resurfacing the layer of the laser direct structuring compound to expose surfaces of the plurality of stud bumps; laser activating the layer of the laser direct structuring compound and thereby forming laser ablated areas; and forming a plurality of electrically-conductive lines at the laser ablated areas, wherein the plurality of electrically-conductive lines are coupled to the plurality of stud bumps, respectively.

14. The method of claim 13, further comprising forming a layer of molding compound covering at least a portion of one of the plurality of electrically-conductive lines.

15. The method of claim 14, wherein the layer of molding compound includes resist material or solder mask material.

16. The method of claim 13, wherein the plurality of stud bumps are a first set of stud bumps, the method comprising forming a second set of stud bumps, wherein resurfacing the layer of the laser direct structuring compound does not expose the second set of stud bumps, wherein laser activating the layer of the laser direct structuring compound comprises exposing the second set of stud bumps.

17. The method of claim 13, further comprising removing the substrate.

18. The method of claim 17, wherein the substrate is one of: a tape material, a paper material, or a metallic material.

19. The method of claim 13, wherein resurfacing the layer of the laser direct structuring compound comprises grinding the layer of the laser direct structuring compound.

20. The method of claim 13, further comprising coupling a heat-sink layer to the semiconductor die at a side that is opposite the plurality of stud bumps.

21. A method, comprising: coupling a semiconductor die to a substrate; forming a plurality of stud bumps on the semiconductor die; covering the semiconductor die and the plurality of stud bumps with a layer of laser direct structuring compound; grinding the layer of laser direct structuring compound and exposing surfaces of the plurality of stud bumps; forming laser ablated areas in the layer of laser direct structuring compound by laser activating the layer of laser direct structuring compound, wherein the laser ablated areas are proximate the exposed surfaces of the plurality of stud bumps; and forming a plurality of electrically-conductive lines at the laser ablated areas, wherein the plurality of electrically-conductive lines are coupled to the plurality of stud bumps, respectively.

22. The method of claim 21, wherein the semiconductor die is a first semiconductor die, the method further comprising coupling a second semiconductor die to the substrate, wherein the covering comprises covering the second semiconductor die.

23. The method of claim 22, wherein the first semiconductor die is stacked onto the second semiconductor die.

24. The method of claim 21, wherein the plurality of stud bumps are a first plurality of stud bumps, wherein forming the laser ablated areas includes forming a through opening exposing a second stud bump, wherein the method further includes filling the through opening with a conductive material to form a conductive through via that is coupled to the second stud bump.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) One or more embodiments will now be described, by way of example only, with reference to the annexed figures, wherein:

(2) FIG. 1 is a cross-sectional view of a semiconductor device according to embodiments;

(3) FIGS. 2, 3 and 4 are exemplary of possible details of one or more embodiments;

(4) FIGS. 5 to 8 are exemplary of possible details of one or more embodiments, each of these figures including two parts, indicated a), b), respectively; of these, parts b) are cross-sectional views along lines Vb-Vb, VIb-VIb, VIIb-VIIb and VIIIb-VIIIb in part a) of the same figure;

(5) FIG. 9, including six parts indicated a) to f) are exemplary of possible acts in a process according to embodiments; and

(6) FIGS. 10 to 12 are cross-sectional views exemplary of possible variants of one or more embodiments.

(7) FIGS. 13A to 13C illustrate cross-sectional views of a portion of a semiconductor device, such as the semiconductor device of FIG. 4, at various stages of manufacture according to one embodiment.

(8) FIGS. 14A to 14G illustrate cross-sectional views of a portion of a semiconductor device, such as the semiconductor device of FIG. 4, at various stages of manufacture according to another embodiment.

(9) FIG. 15 illustrates a cross-sectional view of a semiconductor device according to another embodiment.

(10) FIG. 16 illustrates a cross-sectional view of a semiconductor device according to another embodiment.

(11) It will be appreciated that, for the sake of clarity and ease of understanding, the various views may not be drawn to a same scale.

DETAILED DESCRIPTION

(12) In the ensuing description, one or more specific details are illustrated, aimed at providing an in-depth understanding of examples of embodiments of this description. The embodiments may be obtained without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so that certain aspects of embodiments will not be obscured.

(13) Reference to an embodiment or one embodiment in the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as in an embodiment or in one embodiment that may be present in one or more points of the present description do not necessarily refer to one and the same embodiment. Moreover, particular conformations, structures, or characteristics may be combined in any adequate way in one or more embodiments.

(14) The references used herein are provided merely for convenience and hence do not define the extent of protection or the scope of the embodiments.

(15) In the figures, reference 10 indicates a semiconductor product or package including a semiconductor die or chip 12, which, in one or more embodiments, may be attached (e.g., via a die attach layer 14) onto a layer or substrate 10a.

(16) The substrate 10a may be any material, and in some embodiments the substrate 10a is tape, paper or metal. A metal substrate may be used to provide thermal dissipation, if desired.

(17) The chip or die 12 may be any of a variety of a semiconductor chips or die as conventional in the art. In at least one embodiment, the chip or die 12 includes an active surface including one or more integrated circuits.

(18) Also, while the discussion herein will be provided for simplicity in connection with semiconductor products including one chip or die 12, those skilled in the art will easily understand that one or more embodiments may include a plurality semiconductor chips or dice 12, such as plurality of stacked dice or dice arranged horizontal to each other.

(19) In FIG. 1, reference 16 denotes encapsulation material such as, e.g., a package molding compound (PMC), such as polymers including a polymer resin, having electrically-insulating properties which can be molded onto the chip or die 12. The molding compound is an LDS (Laser Direct Structuring) molding compound (e.g., a thermoplastic/thermoset polymer). In some embodiments, the LDS molding compound includes conductive additives. After areas of the molding compound are activated by the laser, the activated areas may be plated to form lands or traces. In one embodiment, the activation process removes a coating on the conductive additives in the LDS molding compound to form a conductive area configured to receive the plating layer that forms the lands or traces. During laser activation, the laser may also remove portions of the molding compound to form one or more recesses. The laser may be isolated to particular areas to obtain recesses in the molding compound at differing depths. Furthermore, in some embodiments, the parameters of the laser may be adjusted to obtain recesses of differing depths.

(20) In one or more embodiments, conductive stud bumps 18 (formed in manner known per se) are coupled to bond pads of the chip or die 12 and provide electrical connection with respect to the die or chip 12. As shown in FIG. 1, multiple bumping may possibly be included, e.g., when high power driving capability is desired. In particular, a plurality of conductive stud bumps 18 may be coupled to a single bond pad of the die or chip 12 and coupled to a single land 22.

(21) In one or more embodiments, a secondary molding encapsulation 20 can be provided (this can include, e.g., resist or solder mask material depending on applications), along with electro-plated lands 22. These can be provided on the LDS (Laser Direct Structuring) compound by taking advantage of the fact that an LDS compound (e.g., a thermoplastic/thermoset polymer) can be plated after laser activation.

(22) FIG. 2 is an exemplary view of a portion of FIG. 1 at the location indicated by the arrow II reproduced in an enlarged scale and arranged upside-down for further clarity showing an exemplary view of studs bumps 18 after a grinding step (as discussed in the following). FIG. 2 also shows how a laser ablated area 160 of the package 16 may be used (e.g., at a second level of laser ablation) to create a routing of electrically-conductive lines (traces or tracks) 162 over the surface area of the semiconductor product 10.

(23) By way of (non-limiting) reference, the laser ablated area 160 may have a thickness of 50-70 micron (1 micron=10.sup.6 m) with a superposed plated land 22 (possibly having an anchoring shape due to deposit growth) having a thickness of, e.g., 25-50 micron (1 micron=10.sup.6 m).

(24) Still by way of non-limiting example, the land areas 22 may have a width (extension in the main extension plane of the semiconductor product 10) of 50-400 micron (1 micron=10.sup.6 m).

(25) FIG. 3 is another enlarged view of FIG. 1 at a different location than is shown in FIG. 2, and further highlighting the secondary molding encapsulation 20 as obtained, e.g., via a (second) epoxy molding step or applying a solder mask.

(26) FIG. 4 is cross-section view of the semiconductor product and is exemplary of possible approaches in providing routing as exemplified by a trace 162. For instance, one or more embodiments may provide for the creation of a superficial laser scrubbing layer with the possible provision of small stud bumps 180 (having a thickness or height lower than the stud bumps 18) providing electrical contact with (deep) routing traces 162 at a (first) grinding level (1622) with the secondary molding encapsulation 20 formed thereon.

(27) FIGS. 5 and 6 are exemplary of lasering (LDS) processing to produce the laser ablated area 160 around the stud bumps 18 followed by plating including possibly recessed distal portions 220 which, as exemplified by the sequence of FIGS. 7 and 8 may be covered by the second molding step 20.

(28) In one or more embodiments the second molding step may leave the plated areas 22 over the stud bumps 18 exposed to the outer surface of the product package.

(29) In one or more embodiments as shown the electrically-conductive lands 22 may include (e.g., as a result of deposit growth) undercuts providing an anchoring shape for the further molding compound 20.

(30) FIG. 9 summarizes certain steps which may be performed in manufacturing a product as discussed previously.

(31) For instance, part a) of FIG. 9 is exemplary of arranging, onto a sacrificial substrate 10a, one or more semiconductor chips or dice 12 attached (e.g., at 14) onto the substrate 10a) and provided with stud bumps 18.

(32) Part b) of FIG. 9 is exemplary of the provision (e.g., via a conventional film-assisted molding process) of molding material 16 to encapsulate the structure obtained as exemplified at a).

(33) In one or more embodiments, the molding material 16 may include, e.g., an LDS compound.

(34) Part c) of FIG. 9 is exemplary of grinding the surface of the molded mass 16 (e.g., prior to laser activation) in order to expose and flatten the stud bumps 18 to provide a flat top surfaces thereof at the surface of the molded mass 16.

(35) Parts d) and e) of FIG. 9 are exemplary of steps associated with laser activation and/or land manufacturing (such as laser scrubbing+plating, as discussed in the foregoing) followed by a (second) molding step to provide the secondary molding encapsulation 20.

(36) The steps exemplified in parts d) and e) may also include forming laser grooves with different depths on the LDS compound 16 in order to create routing traces 162 as exemplified previously.

(37) Part f) of FIG. 9 is exemplary of final removal (e.g., by stripping or grinding) of the sacrificial substrate 10a, which may permit singulating individual products 10 when plural chips or dice 12 are arranged onto a common substrate 10a as exemplified in part a) of FIG. 9.

(38) One or more embodiments may contemplate applying a flash of gold onto the lands 22.

(39) The basic layout discussed in the foregoing may lend itself to a number of variants.

(40) These may include, e.g., removing the sacrificial substrate 10a at an earlier stage than exemplified in FIG. 9.

(41) Also FIGS. 10 to 12 (where parts/elements like parts/elements already discussed in connection with the previous figures are indicated with like references, thus making it unnecessary to repeat a detailed description herein) exemplify certain variants which may be applied (individually or in possible combinations) to the basic layout discussed in the foregoing.

(42) For instance, reference 10 is exemplary of the possibility of providing top and bottom heat sink layers 30a, 30b coupled with the semiconductor die or chip 12 (e.g., at 14 and 300optionally by using materials having good heat conductivity) with a land 20a provided at the bottom heat sink 30b to provide heat dissipation.

(43) Providing the top heat sink layer 30a may include: selecting thermally dissipative materiale.g., metalfor the substrate 10a, by leaving such a substrate in place (that is by avoiding removing it as exemplified in part f) of FIG. 9), removing the substrate 10a as exemplified in part f) of FIG. 9) and substituting therefor (e.g., via growth or lamination/gluing) a heat dissipative layer 30a.

(44) FIG. 11 is exemplary of the possibility of coupling plural semiconductor chips or dice 12 (e.g., via a common heat sink layer 30a) in a circuit with wire bonding 32 providing electrical connection between the semiconductor chips or dice. In one or more embodiments a potting mass 34 may be provided to protect such wires 32.

(45) FIG. 12 is exemplary of the possible recourse to a stacked semiconductor die or chip arrangement including plural stacked chips or dice 12a, 12b possibly coupled via wire bonding 32.

(46) One or more embodiments may adopt a separation of lands 22 (and the associated stud bumps 18) with power stud bumps 18/lands 22 used for power supply and signal stud bumps 18/lands 22 facilitating signal transfer with respect to the chip or die arrangement as exemplified at 320 on the right-hand side of FIG. 12. Such a possible separation is discussed in detail in a co-pending application filed on even date by the same Applicant.

(47) FIGS. 13A to 13C illustrate method steps in accordance with one embodiment for forming a semiconductor device, such as the semiconductor device of FIG. 4. In particular, FIG. 13A shows a portion of the semiconductor die 12. A first conductive stud bump 18 is on a first bond pad of the semiconductor die and a second, smaller conductive stud bump 180 is on a second bond pad of the semiconductor die. A first layer of LDS molding compound or encapsulation 16 is formed over the first conductive stud bump 18 and the second, smaller conductive stud bump 180.

(48) As shown in FIG. 13B, a thickness of the first layer of LDS molding encapsulation 16 is reduced so that a surface of the first conductive stud bump 18 is exposed, such as by a grinding process. A surface of the first layer of LDS molding encapsulation 16 is coplanar with the first conductive stud bump 18. Portions of the first layer of LDS molding encapsulation 16 is laser activated to form a first recess at the first conductive stud bump 18 and a second recess to expose the second, smaller conductive stud bump 180. To form an opening that exposes the second stud bump 180, the laser may be isolated in that area. Furthermore, different parameters of the laser may be used to form the opening that exposes the second stud bump 180. As shown in FIG. 13C, a plating layer is formed on the laser ablating area 160. The plating layer in the second recess forms a trace 162 and the plating layer in the first recess forms a land 22.

(49) FIGS. 14A to 14G illustrate method steps in accordance with another embodiment for forming a semiconductor device, such as the semiconductor device of FIG. 4. Method steps shown in FIGS. 14A and 14B are the same as the method steps of FIGS. 13A and 13B. In FIG. 14C, however, portions of the first layer of LDS molding encapsulation 16 is laser activated to form recesses of differing depths. In particular, a first laser ablated area of the molding encapsulation forms a first recess 21 at the first conductive stud bump 18 and a second laser ablated area forms a second recess 23 that exposes the second, smaller conductive stud bump 180. The second recess 23 has a greater depth than the first recess 21. Furthermore, the second recess 23 includes an opening at the second, smaller conductive stud bump 180, exposing an upper surface thereof. As mentioned above, the parameters of the laser ablation step, including time exposed to the laser, may be varied to form the different recess depths. The laser ablated areas of the first and second recesses 21, 23 are plated to form a land 22 and a trace 162, respectively, as shown in FIG. 14D.

(50) As shown in FIG. 14E, a second layer of molding encapsulation 20 is formed over the trace 162. The second layer of molding encapsulation 20 is an LDS molding encapsulation and may be the same type of molding encapsulation as the first layer of LDS molding encapsulation. A surface of the second layer of molding encapsulation 20 of is coplanar with a surface of the land 22. As shown in FIG. 14F portions of the second layer of molding encapsulation 20 is laser ablated to form one or more a third recess 27. As shown in FIG. 14G, the additional laser ablated area in the recess is plated to form a contact or trace 25 that is coupled to land 22. The process may continue in which one or more further layers of molding encapsulation may be formed, along with laser activation and plating steps. Lands of the semiconductor device are configured to couple the semiconductor device to another component or device.

(51) FIG. 15 illustrates a cross-sectional view of a semiconductor device according to another embodiment. In the semiconductor device of FIG. 15, portions of the second layer of LDS molding encapsulation 16 is laser ablated to expose a portion of the trace 162. Thus, when plating the trace 25, the trace 25 makes contact with the trace 162 as shown in FIG. 15. Thus, the trace 25 and trace 162 are electrically coupled together.

(52) FIG. 16 illustrates a cross-sectional view of a semiconductor device according to another embodiment. The semiconductor device includes a trace 29 formed on the semiconductor die 12 prior to a molding process. Trace 29 electrically couples the first conductive stud bump 18 to the second, smaller conductive stud bump 180.

(53) It is to be appreciated that one or more embodiments provide additional routing capability of the semiconductor devices. Stud bumps of different height allow for redistribution of the conductive pads of the semiconductor die. Thus, by stacking the molding encapsulation and the traces, electrical connection to the stud bumps conductive pads of the semiconductor die may be redistributed through the molding encapsulation. Thus, by using laser scrubbing or laser structuring to form recesses in the LDS molding encapsulation and adding a plating layer, laser drilled through mold vias (TMV) over bond pads of a die may be avoided. This is beneficial because forming through mold vias can be difficult to form with a laser, particularly when the bond pads are formed with a top layer of aluminum, due to the high reflectance. It will otherwise be appreciated that features/elements exemplified in any one of the figures can be applied (singly or in combination) to embodiments exemplified in any other figure, the embodiments herein having a common feature in that a conventional substrate/lead frame arrangement can be dispensed with.

(54) A method according to one or more embodiments may include: providing an assembly including at least one semiconductor die (or chipe.g., 12) attached (e.g., 14) on a substrate (e.g., 10a), the semiconductor die provided with electrically-conductive stud bumps (e.g., 18) opposite the substrate, the stud bumps embedded in a molding compound (e.g., 16) molded thereon, leveling the molding compound to expose the distal ends of the stud bumps at a surface of the molding compound, forming: i) recessed electrically-conductive lines (e.g., 162) extending over said surface of the molding compound, ii) electrically-conductive lands (e.g., 22) over the distal ends of the stud bumps, providing a further molding compound (e.g., 20) covering the recessed electrically-conductive lines and surrounding the electrically-conductive lands.

(55) One or more embodiments may include removing said substrate, optionally after said leveling, forming and providing said further molding compound.

(56) In one or more embodiments the substrate may include material selected from tape (e.g., organic) material, paper material and metallic material.

(57) In one or more embodiments, leveling the molding compound to expose the distal ends of the stud bumps may include applying grinding to said surface of the molding compound.

(58) In one or more embodiments the molding compound may include laser-activatable direct structuring compound (LDS), optionally including thermoplastic and/or thermoset polymer.

(59) In one or more embodiments, forming the recessed electrically-conductive lines may include applying laser ablation (e.g., 1620) to said surface of the molding compound.

(60) In one or more embodiments, forming the recessed electrically-conductive lines may includes laser activation of the molding compound (16).

(61) In one or more embodiments, secondary stud bumps (e.g., 180) can be electrically coupled with the recessed electrically-conductive lines.

(62) In one or more embodiments, said electrically-conductive lands with undercuts may provide an anchoring shape for the further molding compound.

(63) In one or more embodiments, the further molding compound (e.g., 20) may include resist material or solder mask material.

(64) One or more embodiments may include providing a heat-sink layer over the semiconductor die opposite the stud bumps.

(65) One or more embodiments include providing a thermally-conductive pad (e.g., 20a) at said surface of the molding compound by providing a heat-dissipation path (e.g., 30b) between the semiconductor die and said surface of the molding compound.

(66) One or more embodiments may include providing said assembly with a plurality of semiconductor dice attached to said substrate.

(67) In one or more embodiments may include providing electrical lines (e.g., 32) between the semiconductor dice in said plurality of semiconductor dice, with said electrical lines embedded in a potting mass.

(68) In one or more embodiments a semiconductor device (e.g., 10) may include: at least one semiconductor die provided with electrically-conductive stud bumps embedded in a molding compound molded thereon, wherein the stud bumps include distal ends at a surface of the molding compound, recessed electrically-conductive lines extending over said surface of the molding compound, electrically-conductive lands over the distal ends of the stud bumps, a further molding compound covering the recessed electrically-conductive lines and surrounding the electrically-conductive lands, the semiconductor device optionally produced with the method of one or more embodiments.

(69) One or more embodiments may include at least one semiconductor device according to one or more embodiments, e.g., arranged on a common substrate 30a.

(70) Without prejudice to the underlying principles, the details and embodiments may vary, even significantly, with respect to what has been described, by way of example only, without departing from the extent of protection.

(71) The various embodiments described above can be combined to provide further embodiments. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.