Method of coupling semiconductor dies, tools used and corresponding semiconductor devices
By using stainless steel coils as electrodes and activating the growth of conductive materials with a laser beam, the problem of insufficient conductivity in die-to-die coupling in LDS technology was solved, achieving efficient, low-resistance die-to-die connections and simplifying the process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- STMICROELECTRONICS SRL
- Filing Date
- 2022-07-29
- Publication Date
- 2026-07-14
AI Technical Summary
Existing laser direct forming (LDS) technology suffers from the problem of electrically floating nodes in conductive patterns during die-to-die coupling, resulting in insufficient conductivity and hindering its application in die-to-die coupling.
Stainless steel coils are used as electrodes, and the growth of conductive materials is activated by laser beam energy to form a connection pattern between bare wafers. The conductive path is provided through the electroplating process, thus avoiding the current isolation problem in the electrolyte bath.
It achieves efficient die-to-die electrical connections, reduces resistivity, avoids stress and additional assembly steps, and avoids the drawbacks of conductive paste filling and sacrifice paths, especially in the case of a large number of input/output nodes.
Smart Images
Figure CN115700903B_ABST
Abstract
Description
[0001] Priority requirements
[0002] This application claims priority to Italian patent application No. 102021000020537, filed on July 30, 2021, the contents of which are incorporated herein by reference in their entirety to the fullest extent permitted by law. Technical Field
[0003] This specification relates to semiconductor devices.
[0004] One or more embodiments can be applied to semiconductor devices that include die-to-die connections.
[0005] A system-in-package (SiP) that includes multiple integrated circuits in one or more chip carrier packages can be an example of such a device. Background Technology
[0006] For example, various types of semiconductor devices (such as power devices) may involve die-to-die coupling.
[0007] An example of this is a power semiconductor integrated circuit chip or die (e.g., gallium nitride or GaN) that is expected to be connected to a device that uses a driver chip or die manufactured using BCD (bipolar CMOS-DMOS) technology.
[0008] Laser direct forming (LDS) technology has recently been proposed as an alternative to conventional wire bonding to provide die-to-lead electrical connections in semiconductor devices.
[0009] In the currently implemented laser direct forming technology, after the laser beam forming (activation) of the LDS material, the conductivity formed, such as vias and tracks (traces), is promoted by electroless metallization and electroplating to achieve a metallization thickness of tens of micrometers in the metal material (such as copper).
[0010] One problem with trying to apply LDS technology to die-to-die coupling is that the associated conductive patterns are electrically floating nodes.
[0011] Therefore, the expectation that electroplating would enhance the conductivity of conductive formings (vias and / or lines or tracks) formed via LDS technology would hinder the extension of the use of LDS technology from die-to-lead coupling to die-to-die coupling.
[0012] There is a need for contributions in this field to adequately address this problem. Summary of the Invention
[0013] One or more embodiments relate to a method.
[0014] One or more embodiments relate to a corresponding tool (electrode).
[0015] One or more embodiments relate to a corresponding semiconductor integrated circuit device. A semiconductor device (such as a power device comprising multiple mutually coupled semiconductor chips or dies) can be an example of such a device.
[0016] One or more embodiments provide (temporary) electrical grounding for additional isolated die-to-die connections used when growing conductive material (e.g., metal, such as copper) onto portions of laser-directly formed (LDS) material, which are activated (formed) by applying laser beam energy.
[0017] One or more embodiments may involve using a stainless steel coil located on top of the LDS frame, the stainless steel coil having (e.g., spring-like) fingers that form electrical contacts with a sheet-to-sheet connection pattern.
[0018] One or more embodiments simplify die-to-die coupling without requiring significant changes to the process flow.
[0019] In one or more embodiments, the die-to-die connection line or track may include a landing area to facilitate the formation of electrical contacts (e.g., having an increased area).
[0020] One or more embodiments provide advantageous alternatives to die-to-die coupling obtained using printing methods such as jet printing. Attached Figure Description
[0021] One or more embodiments will now be described by way of example only with reference to the accompanying drawings, wherein:
[0022] Figure 1 This is an example of how LDS technology can be applied to the manufacture of semiconductor devices.
[0023] Figures 2 to 6 These are exemplary steps in the embodiments described herein.
[0024] Figure 7 Further details Figure 4 A plan view of possible implementations of the steps, and
[0025] Figure 8 It is along Figure 7 The cross-sectional view of line VIII-VIII. Detailed Implementation
[0026] Unless otherwise indicated, corresponding numbers and symbols in different figures generally refer to the corresponding parts.
[0027] The accompanying drawings are provided to clearly illustrate relevant aspects of the embodiments and are not necessarily drawn to scale.
[0028] The edges of features drawn in the attached figures do not necessarily indicate the end of the feature range.
[0029] In the following description, various specific details are illustrated to provide a thorough understanding of various examples of the embodiments described. Embodiments may be obtained without one or more 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 various aspects of the embodiments are not obscured.
[0030] References to "embodiment" or "an embodiment" within the framework of this description are intended to indicate that a particular configuration, structure, or feature described with respect to that embodiment is included in at least one embodiment. Therefore, phrases such as "in an embodiment" or "in one embodiment" that may appear at various points in this description do not necessarily refer to exactly the same embodiment. Furthermore, particular configurations, structures, or features may be combined in any suitable manner in one or more embodiments.
[0031] The headings / references used herein are provided for convenience only and are not intended to limit the scope of protection or the scope of the embodiments.
[0032] Figure 1 This represents a potential application of LDS technology in providing die-to-lead coupling in the assembly process of multiple semiconductor devices that are manufactured simultaneously and ultimately separated into individual devices via a dicing step (e.g., Figure 6 exemplified).
[0033] Figure 1 The invention relates to a (single) device including a leadframe having a plurality of die pads 12A (e.g., two die pads), to which a corresponding semiconductor integrated circuit chip or die 14 is mounted (e.g., attached via die attachment material 140) to the die pads 12A, and a lead array 12B surrounding the die pads 12A and the semiconductor chip or die 14.
[0034] The term “lead frame” (or “lead frame”) is currently used (see, for example, the USPC Comprehensive Glossary) to refer to a metal frame that provides support for an integrated circuit chip or die, and electrical leads that interconnect the integrated circuit in the die or chip with other electrical components or contacts.
[0035] Essentially, a leadframe comprises an array of conductive forming elements (leads) extending inward from a contour location along the direction of a semiconductor chip or die, thus forming the array of conductive forming elements from die pads configured to have at least one semiconductor chip or die attached thereon. This can be achieved via conventional methods such as die attach adhesives (e.g., die attach film (DAF)).
[0036] exist Figure 1 In the diagram, two die pads 12A are illustrated, on which corresponding chips 14 are attached. In various embodiments, multiple chips 14 can be mounted on a single die pad 12A: for example, two die pads 12A can be joined to form a single die pad on which two chips are mounted, instead of Figure 1 The different components shown in the diagram.
[0037] Laser direct forming (LDS) (often also known as direct copper interconnect (DCI) technology) is a laser-based processing technology now widely used across various industries in the industrial and consumer electronics markets, such as for high-performance antenna integration, where antenna designs can be directly formed onto molded plastic portions. In an exemplary process, the molded portions can be produced using commercially available resins that include additives suitable for the LDS process; a wide range of resins (such as polymer resins like PC, PC / ABS, ABS, LCP) are currently available for this purpose.
[0038] In LDS, a laser beam can be used to transfer a desired conductive pattern onto a plastic molded part, which is then metallized (e.g., via electroless electroplating of copper or other metals) to ultimately determine the desired conductive pattern.
[0039] Documents such as U.S. Patent Application Publication Nos. 2018 / 0342453, 2019 / 0115287, 2020 / 0203264, 2020 / 0321274, 2021 / 0050226, 2021 / 0050299, or 2021 / 0183748 (all incorporated herein by reference) exemplify the possibilities of applying LDS technology to the manufacture of semiconductor devices. For instance, LDS technology facilitates the replacement of wires, clips, or ribbons with wires / vias created by treating LDS material with a laser beam and then metallizing it (e.g., by growing a metal such as copper through an electroplating process).
[0040] Still refer to Figure 1 The LDS material package 16 can be molded onto lead frames 12A, 12B on which semiconductor chips or dies 14 are mounted.
[0041] The conductive die-to-lead coupling formation can be disposed in LDS material 16 (in a manner known per se: see, for example, the previously cited published application).
[0042] like Figure 1 As illustrated, these die-to-lead coupling formations include: a first via 181, a second via 182, and a conductive line or track 183.
[0043] The first via 181 extends through the LDS package 16 between the top (front) surface 16A of the package (opposite to lead frames 12A, 12B) and the conductive pads (not visible due to scale) on the front or top surface of the chip or die 14.
[0044] The second via 182 extends through the LDS package 16 between the top (front) surface 16A of the package and the corresponding lead 12B in the lead frame.
[0045] Conductive lines or tracks 183 extend at the front or top surface 16A of package 16 and electrically couple a selected first via 181 to a selected second via 182 in second via 182 to provide a desired die-to-lead electrical connection pattern between the chip or die 14 and the lead 12B.
[0046] Providing conductive die-to-lead formations (reference numerals 181, 182, and 183) primarily involves forming these formations in LDS material 16 (e.g., drilling holes in them at desired locations of vias 181, 182), and then growing a conductive material (e.g., a metal, such as copper) at the locations activated (formed) by laser beam energy.
[0047] For example, other details regarding the processing discussed above can be derived from the published applications cited earlier.
[0048] Extending the use of LDS processing discussed above to the production of die-to-die coupling formations presents problems related to the nature of these formations.
[0049] Depend on Figure 1 The die-to-die coupling form indicated by 200 in the figure should preferably include: a conductive via 201 and a conductive line or track 202.
[0050] Conductive via 201 extends through LDS package 16 between the top (front) surface 16A of the package and the die pads (not visible due to scale) on the top or front surface of one and the other of the two chips or dies 14 to be interconnected.
[0051] Conductive lines or tracks 202 extend in a bridge-like manner between first vias 201 on the front or top surface 16A of package 16 to complete the desired die-to-die coupling pattern.
[0052] Laser beam forming (also known as “activation”) of vias 201 and lines or tracks 202 in the LDS material of package 16 can be performed in the same manner as forming vias 181, 182 and lines or tracks 183 used to provide the previously discussed die-to-lead coupling formations.
[0053] A key aspect is growing conductive materials, such as metals (e.g., via electroplating), at structured locations to provide the desired conductivity—as is the case in die-to-lead coupling formations.
[0054] Currently, the growth of this conductive material involves electroplating (in addition to electroless electroplating), which is based on reducing the cations of the metal to be deposited contained in the electrolyte “bath” EB to a metallic material (e.g., copper).
[0055] like Figure 1 Schematic representation: Cations such as Cu2+ cations are reduced to metallic copper at the cathode C by gaining electrons e from an electric current, where A represents the anode of an electrolyte bath containing cations of the metal to be deposited.
[0056] For example (as is known to those skilled in the art), electrolyte EB may contain (in the case of copper deposition) Cu2+ cations and SO2-4 anions.
[0057] This process (i.e., the reduction of Cu2+ cations to metallic copper at the anode to create a conductive path (and therefore, the desired growth of a conductive metal such as copper at the coupling formation 200)) involves the acquisition of electrons e from a current flowing through the cathode C, represented by the lead frame (e.g., lead 12B). This current is fundamentally unable to... Figure 1 In the illustrated arrangement, flow occurs where the forming element 200 is electrically isolated from the lead frame (via chip 14), preventing Cu2+ from being reduced to the metal (copper).
[0058] It is important to note that, at least in principle, this problem can be solved by using only LDS technology to provide the die-to-lead conductive forming elements 181, 182, 183, while other technologies are used to provide... Figure 1 The 200 examples illustrate die-to-die coupling.
[0059] Conventional wire bonding can be considered the primary candidate for die-to-die coupling.
[0060] Undesirable high resistance paths and / or stresses applied to the bonding portions of the device represent (negative) factors to consider.
[0061] Providing a die-to-die coupling form 200 via conductive paste may be another option to consider.
[0062] It should be noted that, due to the viscosity of the slurry, filling the vias formed in LDS material 16 with conductive slurry may become impractical.
[0063] exist Figure 1 Creating a sacrifice path within the structure illustrated in the example may be another option to consider.
[0064] Similarly, this approach cannot avoid drawbacks such as undesirable antenna effects and potential design constraints (especially when the device includes a large number of input / output connections).
[0065] One or more examples considered in this paper fully utilize LDS technology (i.e., also for die-to-die coupling at 200, 201, 202) without affecting the provision of die-to-lead coupling formations 181, 182, and 183.
[0066] Throughout Figures 2 to 8 In, and already combined Figure 1 Similar parts or elements discussed are indicated by the same reference numerals. For the sake of brevity, corresponding detailed descriptions will not be repeated.
[0067] Figure 2 This is an example of multiple semiconductor dies or chips 14 (which will be coupled to each other in a die-to-die connection), shown as being mounted on one or more die pads 12A in a lead frame via die attach material 140.
[0068] LDS material package 16 is molded onto lead frames 12A, 12B on which semiconductor chips or dies 14 are mounted, wherein laser beam forming (e.g., Figure 3 The LB (as indicated in the text) is applied to the structure in the LDS material 16 (once, for example, via thermosetting consolidation) to provide: die-to-lead coupling formations 181, 182 and 183 and die-to-die coupling formations 201, 202.
[0069] To avoid making the representation too cumbersome, the behavior and effects of shaping via laser beam energy LB are described in Figure 3 Examples are given, but laser-formed parts 181, 182, 183 and 201, 202 are not explicitly cited.
[0070] Figure 4 An example of electrode 300 is a coil or strip of a conductor, such as a conductive material (e.g., a metal, such as stainless steel), facing the structure formed by the elements 181, 182, 182, 182, 183 and 201, 202, which has been formed by laser beam energy LB.
[0071] As illustrated, electrode 300 includes contact 302 (examples of which are spring-shaped laminar flow contacts formed in a roll or strip by stamping and bending) adapted to contact a location where a die-to-die connection 200 (via 201 and line or track 202) has been formed.
[0072] In this way (e.g.) Figure 8(For example), those locations of the LDS material may be electrically connected (via electrode 300) to the cathode of the electroplating process.
[0073] Choosing a material such as stainless steel for electrode 300 may be advantageous because steel will not be copper-plated due to its chromium (Cr) content (layer).
[0074] Due to the presence of electrode 300, metals such as copper can be grown at the laser-activated location on the front or top surface 16A of the LDS material 16, not only to provide die-to-lead coupling (vias 181, 182 and wire or track 183), but also to provide die-to-die coupling (via 201 and wire or track 202): see Figure 5 Also refer to Figure 1 .
[0075] Other encapsulation materials 20 (e.g., this could be a non-LDS material, such as conventional epoxy molding compounds) can be molded onto the structure to complete the device encapsulation, and individual devices 10 can be produced via conventional dicing (e.g., by blade cutting), such as Figure 6 Exemplified by B in .
[0076] Figure 7 and Figure 8 This is an example of the possibility of using an external roll to implement electrode 300, which is removed once the electroplating process is complete.
[0077] Figure 7 and Figure 8 This is an example of the possibility of using a single roll to provide the desired electrical contact for multiple devices 10 manufactured simultaneously in a strip, as well as multiple strips.
[0078] The examples discussed in this paper are found to offer better performance compared to wire bonding used in die-to-die connections, for example, by providing connection paths with lower resistivity while avoiding stress and additional assembly steps applied to the device bonding pads.
[0079] Compared to conductive pastes used for die-to-die bonding, the examples in this paper have the advantage of avoiding via filling problems and, more importantly, avoiding additional dispensing steps.
[0080] Compared to providing a sacrifice path within the device structure, one or more examples discussed in this paper have the advantage of avoiding antenna effects and design constraints, especially in the case of a large number of I / O nodes.
[0081] An additional advantage may be related to the fact that the electrode 300 illustrated herein provides a straight electrical path (a layout without bends) in the electrode placement configuration.
[0082] The possible markings left by the contacts 302 of electrode 300 at connection 200 (e.g., at line or track 202) are almost inconspicuous and have no negative impact on device performance under any circumstances.
[0083] Without prejudice to the fundamental principles, details and embodiments may vary, even significantly, relative to what is described by way of example only, without departing from the scope of protection.
[0084] The claims are an integral part of the technical teachings provided herein regarding the embodiments. The scope of protection is defined by the appended claims.
Claims
1. A method for manufacturing a semiconductor bare die, comprising: The first semiconductor die and the second semiconductor die are arranged on the substrate; Laser-directly formed LDS material is packaged and molded onto a first semiconductor die and a second semiconductor die disposed on the substrate, the LDS material package having a surface opposite to the substrate; At least one conductive die-to-die coupling formation is provided between the first semiconductor die and the second semiconductor die, the at least one die-to-die coupling formation comprising: a die via extending through the LDS material between the surface of the LDS material package opposite to the substrate and each of the first and second semiconductor dies; and a die-to-die line extending at the surface of the LDS material package opposite to the substrate and coupling the die via; The at least one die-to-die coupling member providing conductivity includes: Laser beam energy is applied to selected locations on the surface of the LDS material package opposite the substrate to laser activate the LDS material and form the die vias and die-to-die lines therein; The laser-activated and shaped position of the surface of the LDS material encapsulated opposite the substrate is brought into contact with an electrode, wherein the electrode provides a conductive path to the position; and Electrolytic growth of a metal material onto the laser-activated and shaped location on the surface of the LDS material encapsulation, wherein the electrolytic growth of the metal material comprises: exposing the location to an electrolyte carrying cations of the metal material, and reducing the cations to the metal material via an electric current flowing through the conductive path provided by the electrode.
2. The method according to claim 1, comprising: The electrode is disengaged from the location where the metal material is electrolytically grown.
3. The method of claim 1, wherein electrolytically growing the metal material onto the laser-activated and shaped location on the surface of the LDS material encapsulation comprises: The location is exposed to an electrolyte carrying copper cations, and the cations are reduced to metallic copper by an electric current flowing through the conductive path provided by the electrode.
4. The method according to claim 3, wherein the electrolyte carries SO₄²⁻ anions.
5. The method of claim 1, wherein the electrode comprises a layer having a contact member layer protruding from the layer, and wherein the location of the laser-activated and shaped surface of the LDS material encapsulation contacts the electrode comprises: The layered structure of the electrode is arranged to face the surface of the LDS material encapsulation, wherein the contact member protruding from the layered structure contacts the laser-activated and shaped position of the surface of the LDS material encapsulation.
6. The method of claim 5, wherein the contact member protruding from the layered structure of the electrode is deformable in response to laser-activated and shaped contact with the surface encapsulated by the LDS material.
7. The method according to claim 1, comprising: The first semiconductor die and the second semiconductor die are disposed on at least one die pad in the substrate, the substrate including an array of conductive leads surrounding the at least one die pad; as well as LDS processing is applied to the LDS material package to provide a die-to-lead conductive formation that couples a first semiconductor die and a second semiconductor die to selected conductive leads in the conductive lead array, wherein the die-to-lead conductive formation includes: A first via extends through the LDS material between the LDS material-encapsulated surface opposite the substrate and the first semiconductor die and the second semiconductor die; A second via extends through the LDS material between the LDS material-encapsulated surface opposite the substrate and a selected conductive lead in the conductive lead array; and Conductive lines extend at the surface of the LDS material package opposite the substrate, between a selected first via in the first via and a selected second via in the second via.
8. An electrode for electrolytically growing a metallic material onto a laser-activated and shaped location on the surface of an LDS material package to form a die-to-die line between a die via and the die via, for connection to an isolated first semiconductor die and a second semiconductor die, comprising: A layer having at least one contact member protruding from the layer, the layer being configured to be arranged facing the surface encapsulated by the LDS material; as well as At least one contact member protrudes from the layered body and is configured to contact the location of the surface encapsulated by the LDS material, wherein the at least one contact member protruding from the layered body of the electrode is deformable in response to contact with the location of the surface encapsulated by the LDS material.
9. A semiconductor device, comprising: Substrate; A first semiconductor die disposed on the substrate; A second semiconductor die disposed on the substrate; A laser-directly formed LDS material package is molded onto a first semiconductor die and a second semiconductor die, the LDS material package having a surface opposite to the substrate; At least one conductive die-to-die coupling formation between the first semiconductor die and the second semiconductor die, the at least one die-to-die coupling formation comprising: a die via, laser-activated and formed with the LDS material between the surface of the LDS material package opposite the substrate and the first and second semiconductor dies; and a die-to-die line, laser-activated and formed at the surface of the LDS material package opposite the substrate and coupling the die via; and Metallic material is electrolytically grown onto the die vias and the die-to-die line on the surface of the LDS material encapsulated by the LDS material.
10. The semiconductor device according to claim 9: The first semiconductor die and the second semiconductor die are disposed on at least one die pad in the substrate, wherein the substrate includes an array of conductive leads surrounding the at least one die pad; It also includes: a die-to-lead conductive forming element that couples the first semiconductor die and the second semiconductor die to selected conductive leads in the conductive lead array, wherein the die-to-lead conductive forming element includes: A first via extends through the LDS material between the surface of the LDS material package opposite the substrate and one of the first and second semiconductor dies and the other semiconductor die; A second via extends through the LDS material between the LDS material-encapsulated surface opposite the substrate and a selected conductive lead in the conductive lead array; and Conductive lines extend at the surface of the LDS material package opposite the substrate, between a selected first via in the first via and a selected second via in the second via.
11. A method for manufacturing a semiconductor die, comprising: A laser-direct-formed LDS material package is molded over a first circuit and a second circuit, the LDS material package having an upper surface; Laser beam energy is applied to a selected location on the upper surface of the LDS material package to laser activate the LDS material and form a first via and a second via in the LDS material, the first via and the second via extending through the LDS material between the upper surface and the first circuit and the second circuit, respectively. Laser beam energy is applied to a selected location on the upper surface of the LDS material package to laser activate the LDS material and form connecting lines in the LDS material, the connecting lines extending at the upper surface and coupling the first via and the second via; The electrode is brought into contact with at least one of the selected locations of the surface of the LDS material encapsulation that are laser-activated and shaped, wherein the electrode provides a conductive path to the at least one of the selected locations; as well as Electrolytic growth of a metal material is performed on a selected location on the surface of the LDS material encapsulation that is laser-activated and shaped, wherein the electrolytic growth of the metal material comprises: exposing the selected location to an electrolyte carrying cations of the metal material, and reducing the cations to the metal material via an electric current flowing through the conductive path provided by the electrode.
12. The method of claim 11, wherein the electrolyte is an electrolyte carrying copper cations, and the metal material is metallic copper.
13. The method of claim 12, wherein the electrolyte carries SO₄²⁻ anions.
14. The method of claim 11, wherein placing the electrode comprises: Multiple contact components are placed at the selected locations on the surface of the LDS material encapsulated by the laser, which are activated and shaped.
15. The method of claim 14, wherein placing the plurality of contact members comprises: In response to contact with the selected location, the plurality of contact members are deformed.
16. The method of claim 11, wherein the first circuit and the second circuit are supported by a substrate including an array of conductive leads, the method further comprising: Laser beam energy is applied to a selected location on the upper surface of the LDS material package to laser-activate the LDS material and form a third and a fourth via in the LDS material, the third and a fourth via extending through the LDS material between the upper surface and the conductive lead array; as well as Laser beam energy is applied to a selected location on the upper surface of the LDS material package to laser-activate the LDS material and form another connecting line in the LDS material, the other connecting line extending at the upper surface and coupling the third and fourth vias.