Integrated circuit bonding pad with multi-material denticle structure

Abstract

An integrated circuit device can include a multi-material dentiform bonding pad (306, 406, 770, 940, 1102, 1202) including: (a) an array of vertically extending dentiforms (320, 420, 720, 904, 1110, 1204) formed of a first material; and (b) a second material (filler material) (322, 422, 760, 930, 1112, 1206) at least partially filling voids (724, 906, 1206) between the array of dentiforms (320, 420, 720, 904, 1110, 1204). The dentiforms (320, 420, 720, 904, 1110, 1204) can be formed by depositing and etching the first material, and the filler material (322, 422, 760, 930, 1112, 1206) can be deposited on the array of dentiforms (320, 420, 720, 904, 1110, 1204) and etched down into the voids (724, 906, 1206) between the dentiforms (320, 420, 720, 904, 1110, 1204) and expose top surfaces of the dentiforms (320, 420, 720, 904, 1110, 1204). The array of dentiforms (320, 420, 720, 904, 1110, 1204) can collectively define an abrasive structure. The multi-material dentiform bonding pad (306, 406, 770, 940, 1102, 1202) can be bonded to another bonding pad (304, 404, 1142, 1222), e.g., using an ultrasonic or thermal ultrasonic bonding process, during which abrasive dentiforms (320, 420, 720) can abrade, fracture, or remove an undesirable native oxide layer formed on a surface of a respective bonding pad (304, 306, 404, 406, 770), thereby forming a direct bond and / or eutectic bond between the bonding pads (304, 306, 404, 406, 770). The dentiforms (320, 420, 720) can include oxidized dentiforms (324, 424, 754) including an oxide layer (312, 412, 764) formed on each dentiform (320, 420, 720), where the oxide layer (312, 412, 764) formed on each dentiform (320,The integrated circuit device can include an interposer (203, 402, 700, 900, 1100, 1200) and / or an integrated circuit die (300, 400a, 400b, 1140a, 1140b, 1220). The first material can include aluminum, and the second material (322, 422, 760, 930, 1112, 1206) can include silver. Alternatively, the first material can include silicon. The bond pads (1142) configured to bond with the toothed bond pads (1102) can have a three-dimensional shape designed to further improve bonding with the toothed bond pads (1102), e.g., including a three-dimensional shape configured to receive the teeth (1110) of the toothed bond pads (1102); in particular, each bond pad (1142) can include a plurality of protrusions (1144) defining an opening or void (1146) configured to receive the teeth (1110), where the protrusions (1144) can be tapered, rounded, or otherwise configured to facilitate self-alignment of each bond pad (1142) with a corresponding bond pad (1102). Metallic bumps (e.g., gold stud bumps (1230)) can be applied to the bond pads (1222) that are bonded with the multi-material toothed bond pads (1202), where the multi-material toothed bond pads (1202) can be completely covered by an underfill region (1210) (e.g., containing epoxy).

Description

[0001] Related patent applications

[0002] This patent application claims priority to jointly owned U.S. Provisional Patent Application No. 63 / 064958, filed August 13, 2020, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0003] This disclosure relates to integrated circuit (IC) bonding pads, and more specifically to multi-material (e.g., multi-metal) bonding pads having a “tooth-like” structure for improved bonding connections. Background Technology

[0004] Semiconductor bonding pads used to bond a die (chip) to a mounting structure (e.g., an interposer, another die, a package substrate, or other structure) are typically made of aluminum or copper, which readily oxidizes when exposed to air, resulting in a thin, fragile native oxide layer, such as Al₂O₃ or CuO, forming on the exposed surface of each bonding pad. This native oxide itself inhibits direct bonding or eutectic bonding with the pads used to bond the die to the mounting structure. Therefore, bonding techniques must overcome this native oxide barrier to form high-quality, reliable bonds.

[0005] Conventional bonding methods include, for example, wire bonding using high downforce and ultrasonic bonding or thermo-ultrasonic bonding; (b) direct bonding by thermocompression, for example, applying high downforce with applied heat (e.g., in the range of 250°C to 280°C) to break down the native oxide; (c) eutectic bonding; (d) applying oxide inhibitors (e.g., benzotriazole (BTA) or other organic solderability protectants (OSP)) to the exposed surface to slow oxide growth after cleaning; (e) soldering using flux (which burns away the native oxide); or laser soldering (which burns away the native oxide). Thermo-ultrasonic bonding refers to ultrasonic bonding accompanied by the application of heat (e.g., in the range of 200°C to 250°C).

[0006] Each of these conventional bonding techniques has significant drawbacks or limitations.

[0007] For example, wire bonding has various problems and is not suitable for certain die mounting applications. For instance, wire bonding is generally not suitable for die stacking or other three-dimensional die integration. Furthermore, wire bonding is limited by the maximum number of bond points per millimeter. Wire bonding can also cause significant damage to the underlying semiconductor device. In addition, wire bonding connections can introduce noise (e.g., induced noise and capacitance noise) caused by multiple leads that are close together.

[0008] For example, typical soldering techniques for ball grid arrays (BGAs) are difficult to scale up and provide poor thermal resistance. Figure 1A and Figure 1B A cross-sectional side view is shown of a conventional solder bump bonding process for bonding a die 100 to a mounting structure 102 (e.g., an interposer or a package substrate). Figure 1A The arrangement prior to bonding is shown, and Figure 1B The arrangement after weld bonding is shown.

[0009] like Figure 1A As shown, bonding pads 104 on the bottom side of die 100 are aligned above bonding pads 106 on the top side of mounting structure 102. Each bonding pad 104, 106 is typically formed of copper or aluminum. Thin layers of native oxides (e.g., Al2O3 or CuO) may be formed on the bottom surface of bonding pad 104 and the top surface of bonding pad 106, as shown at 110 and 112, respectively. Solder bumps 120 (typically tin) may be formed on bonding pad 106, as shown.

[0010] Next, as Figure 1B As shown, the die 100 is pressed downward toward the mounting structure 102, causing the solder bumps 120 to be physically compressed between the bonding pads 104 and 106. This compression of the solder bumps 120 can break and push aside the native oxide layers 110, 112 to provide direct contact between the solder material (e.g., tin) of the solder bumps 120 and the metal (e.g., aluminum or copper) of each bonding pad 104, 106, thereby defining the solder joint 122.

[0011] However, as noted above, solder ball bonding (e.g., BGA bonding) is difficult to scale up for mounting small devices and typically provides poor thermal resistance.

[0012] Another conventional bonding technique mentioned above is eutectic bonding, such as eutectic Al-Ag-Al bonding. Figure 2A and Figure 2B A cross-sectional side view is shown of a conventional lead-free direct Ag-Al bonding process for bonding a die 200 to a mounting structure 202 (e.g., an interposer or package substrate). Figure 2A The arrangement prior to bonding is shown, and Figure 2B The arrangement after eutectic bonding is shown.

[0013] like Figure 2AAs shown, the Al bonding pad 204 on the bottom side of the die 200 is aligned above the Al bonding pad 206 on the top side of the mounting structure 202. A thin layer of native oxide (e.g., Al2O3) can be formed on the bottom surface of the Al bonding pad 204 and the top surface of the Al bonding pad 206, as shown at 210 and 212, respectively. As shown, a silver (Ag) disk 220 is positioned on the lower Al bonding pad 206.

[0014] Next, as Figure 2B As shown, while heat is applied, the die 200 is pressed downward toward the mounting structure 202, causing the Ag disk 220 to be physically compressed between the Al bonding pads 204 and 206. This thermal compression of the Ag disk 220 induces a eutectic reaction that forms an intermetallic compound (IMC) 222 between the Al bonding pads 204 and 206. Specifically, the IMC 222 comprises a eutectic alloy containing components of the Ag disk 220 and the Al bonding pads 204 and 206, which defines eutectic bonding sites between the Al bonding pads 204 and 206, as known in the art.

[0015] However, such eutectic bonding typically requires very high bonding temperatures (e.g., above 400°C), which can damage many silicon devices. Furthermore, eutectic bonding of aluminum pads is often very difficult due to the native oxide layer protecting the surface of the Al bonding pads.

[0016] Another conventional bonding technique mentioned above is laser welding. Laser welding can effectively remove thin layers of native oxide from the corresponding bonding pads, but it is generally slow and expensive because the laser must heat each individual bond point in the gap space between the structures being bonded together.

[0017] Therefore, there is a need for improved bonding solutions, such as those for heterogeneous integration technologies, such as system-in-package (SiP) applications. Summary of the Invention

[0018] Embodiments of the present invention provide an integrated circuit device comprising a multi-material toothed bonding pad, the multi-material toothed bonding pad comprising: (a) an array of vertically extending teeth formed of a first material (e.g., aluminum), and (b) a filler material different from the first material (e.g., silver) that at least partially fills the voids between the array of teeth. The teeth can be formed by deposition and etching of aluminum or other suitable materials, and the filler material can be deposited above the array of teeth and extending downward into the voids between the teeth, and etched to expose the top surface of the teeth. A very hard native oxide layer (e.g., aluminum oxide) can be formed on the exposed surface of the teeth. The array of teeth can collectively define a ground bonding pad structure. The multi-material toothed bonding pad can be bonded to other bonding pads, for example using an ultrasonic or thermo-ultrasonic bonding process, during which grinding the bonding pads can wear away, break, and / or remove the native oxide layer formed on the teeth and the opposing bonding pads to allow direct bonding and / or eutectic bonding between the bonding pads.

[0019] Some implementations provide multi-material toothed bonding pads and tin-based bonding points suitable for withstanding high temperatures (e.g., suitable for SiC / GaN technology), and direct bonding to aluminum bonding pads can be formed, for example, using ultrasonic or thermosonic bonding tools. Direct bonding to aluminum is typically very difficult due to the resilient native oxide layer protecting the aluminum surface. Multi-material toothed bonding pads can define abrasive structures that allow the protective native oxide layer to wear, break, or be removed.

[0020] In some embodiments, multi-material toothed bonding pads can provide simultaneous contact between multiple types of materials during die mounting. Multi-material toothed bonding pads can form eutectic bonds with opposing bonding pads or structures, and therefore bond at much lower temperatures than conventional bonding pads, especially when applying downforce and / or ultrasonic or thermo-ultrasonic input. In some embodiments, the teeth can be roughened or otherwise modified in various ways to increase the wear and friction generated by the toothed bonding pads, and / or increase the relevant surface area available for bonding.

[0021] In one aspect, an integrated circuit (IC) device includes a metal circuit and at least one multi-material toothed bonding pad connected to the metal circuit. Each multi-material toothed bonding pad includes: (a) a plurality of teeth formed of a first material, and (b) a fill material located between the plurality of teeth formed of a second material different from the first material. The plurality of teeth may define a polishing structure configured to facilitate bonding of another structure to the bonding pad, for example by abrading, breaking, or removing an undesirable native oxide layer between the bonding pad and other structures.

[0022] In some implementations, the IC device includes an interposer or an IC die.

[0023] In some embodiments, the plurality of vertically extending teeth include an oxide layer formed on each vertically extending tooth. In some embodiments, the second material is softer than the oxide layer formed on each vertically extending tooth.

[0024] In some embodiments, the first material comprises aluminum, and the second material comprises silver, tin, indium, or a mixture of two or more of silver, tin, and indium (e.g., 75% Ag and 25% Sn). In other embodiments, the first material comprises silicon.

[0025] In some implementations, each vertically extending tooth has a height-to-width ratio in the range of at least 2, or at least 3, or at least 4, or at least 5, or at least 10, or 2 to 10, for example, in the range of 3 to 5.

[0026] In some implementations, each tooth includes a silicon junction at the exposed surface of the tooth, which increases the roughness of the exposed surface.

[0027] On the other hand, a method for forming a multi-material toothed bonding pad is provided, the method comprising: (a) forming a first layer of a first material; (b) etching the first layer to define a plurality of teeth formed of the first material and an open space between the plurality of teeth; and (c) filling at least partially the open space between the plurality of teeth with a second material different from the first material.

[0028] In some embodiments, the step of filling at least partially the open space between the plurality of teeth with a second material includes: (a) depositing a second layer of the second material on the plurality of teeth and extending downward into the open space between the plurality of teeth; and (b) etching portions of the second material on the plurality of teeth to expose the upper surfaces of the plurality of teeth.

[0029] In some implementations, the first material is harder than the second material.

[0030] In some embodiments, the first material comprises aluminum, and the second material comprises silver, tin, indium, or a mixture of two or more of silver, tin, and indium (e.g., 75% Ag and 25% Sn).

[0031] In some embodiments, a roughening process to increase the surface roughness of the multiple teeth is performed before the open space is filled with a second material. For example, the roughening process may include wet etching or oxidation of the exposed surfaces of the multiple teeth to increase their porosity.

[0032] Another aspect provides an IC device bonding method. A first IC device is provided, comprising: a first IC device bonding pad including: (i) a plurality of oxide teeth, each oxide tooth including a vertically extending tooth formed of a first material and a first oxide layer formed on the vertically extending tooth; and (ii) a second material disposed in the space between the plurality of oxide teeth, the second material being different from the first material, wherein the plurality of oxide teeth define a polishing structure. A bonding process is performed to bond the first IC device bonding pad of the first IC device to a second IC device bonding pad of a second IC device, the second IC device bonding pad having a second oxide layer formed thereon. During the bonding process, the polishing structure defined by the plurality of oxide teeth of the bonding pad of the first IC device interacts with the second oxide layer formed on the second IC device bonding pad to cause the first oxide layer formed on the vertically extending tooth and the second oxide layer formed on the second IC device bonding pad to wear, break, or be removed.

[0033] In some implementations, the bonding process includes applying ultrasonic energy or thermo-ultrasonic energy to at least one of a first IC device bonding pad and a second IC device bonding pad.

[0034] In some implementations, the bonding process causes eutectic bonding between the first IC device bonding pad and the second IC device bonding pad.

[0035] In some embodiments, the bonding process causes (a) a first material forming vertically extending teeth of a first IC device bonding pad, (b) a second material disposed in the space between the plurality of vertically extending teeth, and (c) eutectic bonding between the second IC device bonding pads. In some embodiments, the first material comprises aluminum, the second material comprises silver, and the second IC device bonding pads comprise aluminum. Attached Figure Description

[0036] Example aspects of this disclosure are described below with reference to the accompanying drawings, in which:

[0037] Figure 1A and Figure 1B A cross-sectional side view is shown of a conventional solder bump bonding process for bonding a bare die to a mounting structure;

[0038] Figure 2A and Figure 2B A cross-sectional side view is shown of a conventional direct (eutectic) bonding process for bonding a bare die to a mounting structure;

[0039] Figure 3A and Figure 3BA cross-sectional side view of an exemplary embodiment of the present invention is shown, illustrating the bonding of a bare die to a mounting structure using at least one multi-material toothed bonding pad;

[0040] Figure 4A and Figure 4B A cross-sectional side view according to an exemplary embodiment is shown, illustrating the process of bonding two exemplary dies to a mounting structure using multi-material toothed bonding pads;

[0041] Figure 5 This is a cross-sectional side view of a filled TSV interpolator mounted on a package substrate according to an exemplary embodiment;

[0042] Figure 6 This is a cross-sectional side view of a filled intercalator, which is mounted and wire-bonded to a package substrate, according to another exemplary embodiment.

[0043] Figures 7A to 7E This is a cross-sectional side view according to an embodiment of the present invention, illustrating the process for forming a mounting structure including multi-material toothed bonding pads and bonding a die to such bonding pads;

[0044] Figure 8 An example of a SiO2 nanojunction according to an embodiment of the present invention is shown, which is formed on the top surface of a pair of aluminum teeth for enhancing wear during bonding;

[0045] Figure 9A and Figure 9B A cross-sectional view of an exemplary process according to an embodiment of the present invention is shown, the exemplary process for forming a multi-material toothed bonding pad including an array of tiny toothed features defining “grass-like” regions to form an extremely rough bonding pad surface;

[0046] Figure 10A An exemplary electron microscope image of an exemplary grass-like region formed from black silicon is shown;

[0047] Figure 10B An exemplary electron microscope image of a single black silicon spiral is shown;

[0048] Figure 11A and Figure 11B An exemplary embodiment is shown, wherein each die includes a bonding pad shaped to receive a corresponding multi-material toothed bonding pad on a mounting structure (e.g., an interposer or a package substrate); and

[0049] Figure 12A and Figure 12BAn exemplary embodiment is shown in which gold pillar bumps are applied to the bonding pads of a bare die (which is being mounted to a mounting structure having multi-material toothed bonding pads).

[0050] It should be understood that reference numerals for any illustrated element appearing in multiple different figures have the same meaning in all figures, and any illustrated element mentioned or discussed herein in the context of any particular figure also applies to every other figure (if any) in which the same illustrated element is shown. Detailed Implementation

[0051] Embodiments of the present invention provide multi-material toothed bonding pads, methods for forming such bonding pads, and methods for improved bonding of IC devices using such bonding pads.

[0052] Figure 3A and Figure 3B A cross-sectional side view according to an exemplary embodiment of the present invention is shown, illustrating the bonding of a die 300 to a mounting structure 302 using at least one multi-material toothed bonding pad. Figure 3A The arrangement prior to bonding is shown, and Figure 3B The arrangement after solder bonding is shown. As used herein, a “mounting structure” may include an interposer, package substrate, or any other integrated circuit device to which one or more dies may be mounted.

[0053] like Figure 3A As shown, bonding pads 304 on the bottom side of die 300 are aligned above bonding pads 306 on the top side of mounting structure 302. The bonding pads 304 formed on die 300 may be formed of copper (Cu), aluminum (Al), nickel (Ni), gold (Au), or any other suitable bonding pad material. Multi-material bonding pads 306 may include: (a) an array of vertically extending protrusions, referred herein as teeth 320 formed of a first metal; and (b) a filler material 322 comprising a second metal, arranged between the individual teeth 320 such that the two different metals of the teeth 320 and the filler material 322 are arranged in an interlaced or staggered manner. Bonding pads 306 may include any number of teeth 320, for example, in the range of 2 to 10,000 teeth 320. The term "vertically extending" is used herein in the context of horizontally oriented mounting structures, for example, as shown in the figures. If the relevant mounting structure of any publicly disclosed implementation is vertically oriented, the teeth will extend horizontally.

[0054] As used herein, "tooth" can include any vertically tapering structure, such as in the form of a tooth, spike, spiral, blade, tube, or rod; it can be symmetrical or asymmetrical around each axis; it may or may not be tapered; and it can have a sharp, smooth, blunt, or rough upper tip or end, i.e., the tip or end of the tooth away from the associated mounting structure 302. The tooth 320 can be formed of a material from which a hard primary oxide layer is grown, such as aluminum from which primary alumina (Al₂O₃) is grown, tungsten from which primary tungsten oxide (WO₃) is grown, or silicon from which silicon dioxide (SiO₂) is grown. In some embodiments, the tooth itself is formed of a hard material, such as tungsten teeth or silicon teeth.

[0055] Filler material 322 can be added between the individual teeth 320 of each toothed bonding pad 306 in any suitable manner, for example, by depositing a layer of filler material extending downward into the space between the teeth 320 and removing portions of the filler material covering the top of the teeth 320 and located between adjacent toothed bonding pads 306. In some embodiments, filler material 322 can be added prior to the growth of a native oxide layer (e.g., an Al2O3 layer) to provide direct contact between filler material 322 and the teeth 320. In such embodiments, the native oxide layer can be grown only on the surfaces of the teeth 320 that remain exposed after the addition of filler material 322 (e.g., at or near the upper ends or tips of the teeth 320). For example, in Figure 3A In the illustrated embodiment, a primary oxide layer 312 comprising aluminum oxide (Al2O3) may be formed on the exposed upper surface of each aluminum tooth 320, while the exposed upper surface of the silver filler material remains substantially oxide-free. In other embodiments, depending on the composition of the tooth 320 and the filler material 322, one or more primary oxide layers may be formed on both the exposed upper surface region of each tooth 320 and the exposed upper surface region of the filler material 322.

[0056] Similar to oxide layer 312, depending on the composition of bonding pad 304, a thin native oxide layer 310 (e.g., native Al2O3 or CuO layer) may also be formed on the mounting side of bonding pad 304 (i.e., the side of bonding pad 304 to be mounted onto bonding pad 306).

[0057] Each tooth 320 (having a native oxide layer 312 formed on the upper end or tip of the tooth 320) may herein be referred to as an oxide tooth indicated at 324. The upper end or tip of the oxide tooth 324 included in each bonding pad 306 (including the native oxide layer 312 on the upper end or tip of the corresponding tooth 320) may collectively define a hard abrasion structure indicated at 326. The abrasion structure 326 may be adapted to abrade or rub the native oxide layer 310 formed on the bonding pad 304 to wear, break, and / or remove the native oxide layers 310 and 312 on the bonding pads 304 and 306, respectively, which may allow direct bonding and / or eutectic bonding between the materials of the bonding pads 304 and 306, as referred to below. Figure 3B The discussion.

[0058] In some embodiments, the teeth 320 may be roughened before the formation of the primary oxide 312. For example, when using chlorine-based plasma etching (dry etching) to form the teeth 320 from an aluminum layer, various process parameters of the chlorine-based plasma etching can be selected or controlled to increase the porosity of the outer surface of the teeth 320 (e.g., by creating small cracks or voids in the aluminum). Alternatively, HCl wet etching can be performed to increase the porosity of the aluminum surface.

[0059] The filler material 322 may comprise a metal, metal alloy, or other material that (a) can form eutectic bonds with opposing bonding pads or other bonding structures (e.g., comprising aluminum or copper) at a low eutectic temperature (e.g., below 500°C, below 400°C, or below 300°C), and / or (b) is softer than the native oxide 312 (e.g., Al2O3, WO3, or SiO2 in the case of aluminum, tungsten, or silicon teeth 320) formed on the teeth 320 and / or the material forming the teeth 320 itself (e.g., in the case of tungsten or silicon teeth 320). For example, in some embodiments, the filler material 322 may comprise silver, tin, or indium, or a mixture of silver, tin, and indium (e.g., a mixture of 75% Ag and 25% Sn), which is suitable for forming eutectic bonds with aluminum or copper bonding pads 306, for example, to form strongly conductive bonds between bonding pads 304 and 306. According to a specific implementation, the filling material 322 can partially or completely fill the space between adjacent teeth 320.

[0060] Next, refer to Figure 3BThe die 300 can be bonded to the mounting structure 302 via direct bonding and / or eutectic bonding. In some embodiments, the die 300 can be pressed downward toward the mounting structure 302 while ultrasonic vibration (including lateral vibration) and / or heat are applied to at least one of the die 300 / bonding pad 304 and the mounting structure 302 bonding pad 306. For example, an ultrasonic head or a thermo-ultrasonic head can apply downward pressure, ultrasonic energy (causing vibration), and / or heat to the die 300, which is transferred to the bonding pad 304. Furthermore, the mounting structure 302 can be heated by heating the chuck supporting it, which is transferred to the multimaterial bonding pad 306. Alternatively, the bonding process can be performed in an oven.

[0061] During an ultrasonic or thermo-ultrasonic bonding process, an abrasive structure 326 defined by the oxide serrations 324 of the bonding pad 306 can abrade the oxide layer 310 of the bonding pad 304 to wear, break, and / or remove the native oxide layers 310 and 312, thereby allowing direct bonding and / or eutectic bonding between the bonding pad 304 and the bonding pad 306. For example, in embodiments including aluminum serrations 320, a hard alumina layer 312 on each serration 320 abrades the oxide layer 312 on the bonding pad 304, or vice versa. In embodiments including harder serrations 320, such as those formed of tungsten or silicon, the serrations 320 can engage with the associated oxide layer 312 on the serrations 320 to abrade the oxide layer 312 on the bonding pad 304.

[0062] Depending on specific process parameters (e.g., selected materials for bonding pads 304 and 306, temperatures of bonding pads 304 and 306 during bonding, downward pressure applied to bonding pad 304, and vibrational force / movement caused by ultrasonic energy), the resulting bonding may involve one or both of the following: (a) direct bonding between bonding pads 304 and 306 (e.g., between bonding pads 304, teeth 320, and filler material 322); and / or (b) eutectic bonding between bonding pads 304 and 306, wherein filler material 322 (e.g., aluminum) can help form a eutectic IMC layer 330 between (a) bonding pads 304 (e.g., aluminum) and / or (b) filler material 322 (e.g., silver) and / or teeth 320 (e.g., aluminum) of 306.

[0063] In some embodiments, the oxide tooth 324 may be roughened prior to the bonding process to further enhance the polished structure 326 to facilitate the bonding process. For example, the oxide tooth 324 may also be oxidized, for instance, in a stripping cavity to increase the thickness and roughness of the oxide layer 312 on the tooth 320. Alternatively, a hydrogen chloride (HCl) wet etching process may be performed on the oxide tooth 324 to increase the porosity of the native oxide 312 and / or the underlying tooth metal (e.g., aluminum), which can increase the surface roughness of the oxide tooth 324.

[0064] Figure 4A and Figure 4B A cross-sectional side view according to an exemplary embodiment is shown, illustrating the process of bonding two exemplary dies 400a and 400b to a mounting structure 402 using multimaterial toothed bonding pads 406. In this example, the mounting structure 402 is an interposer. Figure 4A The arrangement prior to bonding the dies 400a and 400b to the interpolator 402 is shown, and Figure 4B The arrangement after bonding bare dies 400a and 400b is shown.

[0065] Each die 400a and 400b may comprise any type of semiconductor die, such as a field-programmable gate array (FPGA) or other processor die, microcontroller, serializer / deserializer (SerDes) die, memory die, or any other type of die. As shown, each die 400a and 400b includes at least one bonding pad 404 formed in a passivation region 414. Each bonding pad 404 may be formed of copper (Cu), aluminum (Al), nickel (Ni), gold (Au), or any other suitable bonding pad material. The passivation region 414 may include, for example, regions comprising oxides and oxide nitrides. A thin native oxide layer 410 may be formed on the bottom of each bonding pad 404.

[0066] The interposer 402 may include an interposer or other structure for mounting dies 400a, 400b and may be supported on a chuck 460. The interposer 402 may include circuitry including a metal layer 430 formed over a silicon substrate 432. The metal layer 430 may include, for example, aluminum or copper interconnect layers formed in a dielectric region 434 formed over the interposer silicon substrate 432. The dielectric region 434 may include any number of oxide layers or other dielectric layers. In some embodiments, the interposer 402 may be a through-silicon via (TSV) interposer, which may include a plurality of TSV contacts 438 extending through the interposer silicon substrate 432 to provide electrical connections between the metal layer 430 and selected circuitry or other structures on a package substrate, for example, as discussed below. Figure 5As shown. In other embodiments, the interposer 402 can be configured to use the bonding pad 408 (e.g., as shown). Figure 6 As shown below, wire bonding attachment is performed on the package substrate or other structures, and therefore the TSV contact 438 can be omitted.

[0067] Multiple multi-material toothed bonding pads 406 and (optionally) test pads or wire bonding pads 408 may be formed on the top side of the insert 402 and connected to the top metal layer 430 via conductive vias 436 (e.g., tungsten or copper vias). Each multi-material toothed bonding pad 406 may be coupled with... Figures 3A to 3B This corresponds to the bonding pad 306 shown and discussed above. Therefore, each multi-material toothed bonding pad 406 may include (a) an array of vertically extending teeth 420 formed of a first material (e.g., aluminum) and a filler material 422 containing a second material (e.g., silver) disposed between the individual teeth 420, such that the two different materials, teeth 420 and filler material 422, are arranged in an interlaced or staggered manner.

[0068] A primary oxide layer 412 (e.g., an Al2O3 layer 412, in the case of aluminum teeth 420) may be formed on the exposed upper surface of each tooth 420 to define an oxide tooth 424, for example, as described above regarding Figure 3A As discussed above. In some embodiments, for example, an epoxy resin-containing underfill layer 440 may be formed between bonding pads 406 and / or 408, which may provide physical support for the bare dies 400a, 400b (once installed) and / or provide moisture sealing for the circuitry of the interposer 402 and the bare dies 400a, 400b.

[0069] Test pads or wire bonding pads 408 can be formed together with multi-material toothed bonding pads 406, but can also be formed as solid metal pads (e.g., aluminum).

[0070] refer to Figure 4BDies 400a and 400b can be bonded to interposer 402 via direct bonding and / or eutectic bonding, similar to the bonding of die 300 to mounting structure 302 discussed above. The resulting filled interposer is indicated at 470. For example, dies 400a and 400b can be pressed downward toward interposer 402 while applying heat and ultrasonic vibration (including lateral vibration) to one or more associated structures, such as dies 400a and 400b, bonding pad 404, interposer 402, and / or bonding pad 406. For example, an ultrasonic head or thermo-ultrasonic head 450 can apply downward pressure, ultrasonic energy (causing vibration), and / or heat to dies 400a and 400b. Furthermore, interposer 402 and / or bonding pad 406 can be heated by heating the chuck 460 supporting interposer 402 or by performing the bonding process in an oven.

[0071] As mentioned above Figure 3A As discussed, the upper ends or tips of the oxide serrations 424 in each bonding pad 406 can collectively define a hard abrasive structure 426. During ultrasonic or thermo-ultrasonic bonding processes, the abrasive structure 426 defined by the oxide serrations 424 can be adapted to abrade or rub the native oxide layers 410 formed on the bonding pads 404 of the bare wafers 400a, 400b, to wear, break, and / or remove the native oxide layers 410 and 412 on the bonding pads 404 and 406, respectively. This can allow direct bonding and / or eutectic bonding between the materials of the bonding pads 404 and 406. Furthermore, the wear caused by the abrasive structure 426 can generate localized frictional heating, which can further promote the bonding process. Depending on specific process parameters (e.g., selected materials of bonding pads 404 and 406, downward pressure applied to bonding pad 404 by ultrasonic or thermo-ultrasound head 450, vibrational force / movement caused by ultrasonic energy) and / or the temperature of bonding pads 404 and 406 during bonding (e.g., increased by heat from head 450 in embodiments where head 450 includes a thermo-ultrasound head, or from heat from an oven or other heating system), the resulting bonding may involve one or both of the following: (a) direct bonding between each bonding pad 404 and the teeth 420 and filler material 422 of the opposite bonding pad 406; and / or (b) eutectic bonding between each bonding pad 404 and the teeth 420 and filler material 422 of the opposite bonding pad 406, wherein the filler material 422 helps to form the eutectic IMC between bonding pads 404 and 406. As indicated above, in one embodiment, the teeth 420 are formed of aluminum, and the filler material 422 contains silver.

[0072] In some embodiments, as discussed above, the tooth 420 may be roughened before or after the formation of the primary oxide layer 412 on the tooth 420 to further enhance the abrasive properties of the oxidized tooth 424. For example, the tooth 420 may be roughened before the formation of the primary oxide 412 by controlling the process parameters of the chlorine-based plasma etching process that forms the tooth 420 to increase the porosity of the outer surface of the tooth 420 (e.g., by forming small cracks or voids in aluminum). Alternatively, HCl wet etching may be performed to increase the porosity of the surface of the tooth 420. Alternatively, after the formation of the primary oxide layer 412, the oxidized tooth 424 may also be oxidized, for example, in a stripping chamber to increase the thickness and roughness of the oxide layer 412 on the tooth 420. For example, hydrogen chloride (HCl) wet etching can be performed on the oxide tooth 424 to increase the porosity of the native oxide 412 and / or the underlying tooth metal (e.g., aluminum), for example, to increase the surface porosity of the tooth 420 to a range of 5% to 40% (in some embodiments, a range of 20% to 40%).

[0073] Figure 4B The filled interposer 470 shown (including dies 400a and 400b bonded to interposer 402) can be mounted to a package substrate or other structure in any suitable manner, for example, using through-silicon vias (TSVs) or by wire bonding.

[0074] Figure 5 This is an illustration of a package substrate 500 mounted on an exemplary embodiment. Figure 4B A cross-sectional side view of the filled interposer 470. In this embodiment, the interposer 470 is a TSV interposer including, for example, a plurality of TSV contacts 438 formed of copper. The package substrate 500 may include, for example, a package substrate through-hole 502 formed of copper, which extends through the vertical thickness of the package substrate 500. The package substrate 500 may be mounted to a printed circuit board (PCB) 504 or other electronic device, for example, using a ball grid array (BGA) 506 or other solder brackets.

[0075] Figure 6 It is shown that the package is mounted on the packaging substrate 600 according to another exemplary embodiment. Figure 4B A cross-sectional side view of the filled interposer 470. In this embodiment, the interposer 470 can be mounted on the package substrate 600 using adhesive and is electrically connected to the package substrate 600 via wire bonds 602 formed between bonding pads 408 on the interposer 470 and bonding pads 604 (e.g., solid aluminum pads) on the package substrate 600.

[0076] Figures 7A to 7EThis is a cross-sectional side view according to one embodiment of the invention, illustrating the process for forming a mounting structure including multimaterial toothed bonding pads and bonding a die (e.g., a horizontally mounted die or HMD) to such multimaterial toothed bonding pads. In this example, the mounting structure is an interposer; however, in other embodiments, the mounting structure may be a package substrate or any other suitable integrated circuit device. While the use of aluminum and silver has been specifically detailed, this is not intended to limit it in any way, and other materials may be utilized without exceeding certain limits.

[0077] First refer to Figure 7A An interposer structure 700 is constructed by forming metal interconnect circuitry on an interposer substrate 702 (e.g., a silicon substrate). This interposer structure may include any number of metal layers 704 connected by vias 706, formed in dielectric regions 710 comprising any number of oxide layers or other dielectric layers. In one exemplary embodiment, the metal layers 704 are formed of aluminum, and the vias 706 are formed of tungsten. In another embodiment, the metal layers 704 may be formed using a copper damascene process.

[0078] Next, refer to Figure 7B A relatively thick aluminum layer (e.g., greater than 1 μm, greater than 2 μm, or greater than 3 μm thick) can be deposited on the top surface 712 of the interposer structure 700 and etched, for example, using chlorine-based plasma etching (dry etching) to define a plurality of aluminum structures including aluminum teeth 720 (and, in some embodiments, at least one solid aluminum pad 740). Each solid aluminum pad 740 may be a test pad or a wire bonding pad. The aluminum teeth 720 may be formed in local groups 722, wherein each tooth group 722 includes an array of individual teeth 720 separated from each other by open spaces or gaps 724. Each tooth group 722 defines a first component of a corresponding multimaterial toothed bonding pad that has been constructed. An illustrative example shows two tooth groups 722 for two multimaterial toothed bonding pads that have been formed.

[0079] Each tooth group 722 may include any number of teeth 720 arranged in a one-dimensional or two-dimensional array of teeth 720. Each tooth group 722 may include 2 to 10,000 teeth 720. Each tooth 720 may have any suitable shape and size. For example, each tooth 720 may have a conical shape, such as a generally conical or pyramidal shape, wherein the sidewall conical shape is defined by a cone angle θ relative to the top surface 712. In some embodiments, each tooth 720 may have one, some, or all of the following dimensional characteristics:

[0080] (a) Vertical height H in the range of 1 μm to 5 μm齿状物 (in the z direction);

[0081] (b) Lateral width W in the range of 0.13 μm to 2 μm 齿状物 (In the forward x and / or y directions), defined at the base of the tooth 720;

[0082] (c) Height to width ratio H 齿状物 / W 齿状物 At least 2, or at least 3, or at least 4, or at least 5, or at least 10, or in the range of 2 to 10, for example in the range of 3 to 5;

[0083] (d) Lateral spacing SP between the central axes of adjacent teeth 齿状物 (In the forward x-direction and / or y-direction), within the range of 0.3 μm to 10 μm, for example, within the range of 1 μm to 6 μm; and / or

[0084] (e) Sidewall cone angle θ, in the range of 0° to 45°, for example, in the range of 5° to 30°.

[0085] Adjacent teeth 720 can be laterally spaced apart from each other through open spaces or gaps 724 (e.g., as shown in the image). Figure 7B (as shown in the exemplary embodiments), or the corresponding teeth 720 may be physically coupled to a certain height (e.g., such that each tooth 720 has a lower base portion coupled to at least one adjacent tooth 720, but the upper portion is spaced apart from each adjacent tooth 720 (in the lateral direction).

[0086] Each solid aluminum pad 740 (e.g., a test pad or wire bonding pad) may be substantially wider than any of the teeth 720. For example, each solid aluminum pad 740 may have a width W. 焊盘 (In the forward x and / or y directions) (which are in the range of 10 μm to 100 μm, for example in the range of 30 μm to 60 μm), and may have the same or different dimensions as other solid aluminum pads 740.

[0087] Next, refer to Figure 7C The exposed surfaces of the tooth-like structure 720 (including the top surface 750 and the sidewall surface 752) can be roughened, for example, as described above relative to... Figure 3B and Figure 4BAs discussed above. For example, when using chlorine-based plasma etching (dry etching) to form the tooth 720 from an aluminum layer, various process parameters of the chlorine-based plasma etching can be selected or controlled to increase the porosity (percentage of void space) of the surfaces 750, 752 of the tooth 720 (e.g., by forming small cracks or voids in the aluminum) to a range of 5% to 40% (in some embodiments, in the range of 20% to 40%). Alternatively, HCl wet etching can be performed to increase the porosity of the aluminum surface of the tooth 720. Furthermore, the tooth 720 can be formed from silicon-doped aluminum, and post-etching processes can be performed to form SiO2 nanojunctions at the surface, thereby increasing surface roughness.

[0088] In some implementations, roughening techniques can increase the arithmetic mean roughness Ra of surfaces 750 and 752, for example, by increasing it to a roughness value Ra greater than 5 nm, greater than 10 nm, greater than 15 nm, or greater than 20 nm.

[0089] Next, as Figure 7D As shown, the open spaces or gaps 724 between the teeth 720 in each tooth group 722 can be filled (partially or completely) with a second different material (such as silver) indicated at 760, to define a multi-material toothed bonding pad 770 by each tooth group 722. For example, a silver layer (e.g., with a thickness of [missing information]) can be deposited on the structure (extending to the top surface 712 of the teeth 720 and the interposer structure 700). to ), and for example, using anisotropic etching to etch back onto it to partially or completely fill the open spaces or gaps 724 between the teeth 720 in each tooth group 722 and also cover the outer surface 752 of the outer teeth 720 in each tooth group 722, such as Figure 7D As shown. Etching can remove the silver layer on the top surface 750 of the tooth 720, thereby exposing the top tooth surface 750.

[0090] As discussed above, a primary oxide layer (Al2O3) 764 can be grown on the exposed top surface 750 of the tooth 720 to define an oxide tooth 754. In some embodiments, the oxide tooth 754 can be roughened to further enhance its abrasive properties. For example, the oxide tooth 754 can also be oxidized, for example, in a desizing chamber to increase the thickness and roughness of the primary oxide layer 764 on the tooth 720. Alternatively, a hydrogen chloride (HCl) wet etching process can be performed on the oxide tooth 754 to increase the porosity of the primary oxide 764 and / or the underlying tooth metal (e.g., aluminum), which can increase the surface roughness of the oxide tooth 754.

[0091] The oxide teeth and / or additional roughened teeth 754 included in each multi-material toothed bonding pad 770 can collectively define a hard-grinding structure configured to grind the oxide layer of the opposing bonding pad to wear, break and / or remove such oxide layers and oxide layers 764 on the oxide teeth 754, thereby allowing direct contact and / or eutectic contact between the bonding pad 770 and the opposing bonding pad, as discussed above.

[0092] Finally, as Figure 7E As shown, a template or needle can be used to deposit the underfill 774, for example, containing epoxy resin. The height of the underfill 774 can be adjusted as needed based on the shape and / or size of the die to be installed into the inserter 700.

[0093] As noted above, in some embodiments, the teeth 720 may be formed of silicon-doped aluminum (e.g., silicon doping in the range of 0.1% to 5%), and a post-etching process may be performed to form SiO2 nanojunctions on the aluminum surface, thereby increasing surface roughness. Rapid thermal annealing (RTA) may be performed to force the Si dopant within the aluminum to aggregate and form submicron nodules. An O2 re-oxidation process may then be performed to form SiO2 nanojunctions on the surface of the aluminum teeth 720, thereby increasing surface roughness.

[0094] Figure 8 An example of SiO2 nanojunctions 800 formed on the top surface 750 of a pair of aluminum teeth 720 is shown.

[0095] Figure 9A and Figure 9B A cross-sectional view of an exemplary process according to an embodiment of the present invention is shown, the exemplary process for forming multi-material toothed bonding pads including an array of tiny tooth-like structures defining “grass-like” regions to form a very rough bonding pad structure.

[0096] like Figure 9AAs shown, three grass-like regions 902 are formed on the top surface 916 of a mounting structure (e.g., an interposer 900 that may resemble the interposer 700 discussed above, for example, including a metal layer 910 and via 912 formed in a dielectric region 914 above an interposer substrate 920). Each grass-like region 902 may include an array of narrow teeth, spikes, spirals, or “blades” 904 (referred to as teeth 904 for simplicity) separated by open spaces or gaps 906 to form a grass-like structure. The grass-like regions 902 may be formed of silicon or aluminum or other suitable metals and may be formed in any suitable manner. In some embodiments, each grass-like region 902 may include an array of silicon spirals. For example, a silicon “grass” region including an array of teeth 904 may be grown for each region 902. For example, as is known in the art, the region of the black silicon tooth 904 can be formed by depositing a black silicon layer and performing reactive ion etching (RIE), for example, as described in “A Survey on the Reactive Ion Etching of Silicon in Microtechnology”, published in the Journal of Micromechanics and Microengineering in March 1996 by HV Jansen, Han Gardeniers, MJ Boer, M. Elwenspoek, and Jan Fluitman.

[0097] In some embodiments, a chemical treatment may be performed to produce black silicon with nanopores, which may further increase the roughness of each grass-like region 902. It is known in the art that silicon can be conductive (especially when coated with silver or other suitable materials), for example, as a filling material in the open spaces or voids 906 between the silicon teeth 904 in each grass-like region 902.

[0098] like Figure 9B As shown, the open spaces or gaps 906 between the teeth 904 in each grass-like region 902 can be filled (partially or completely) with silver or other suitable filler metal, indicated at 930. For example, a silver layer (e.g., with a thickness of [missing information]) can be deposited on the structure (extending to the top surface 916 of the teeth 904 and the inserter 900). to The etching process involves etching back, for example, using anisotropic etching, to partially or completely fill the open spaces or gaps 906 between the vertically extending teeth 904 in the grass-like region 902, and also covering the outer surface 922 of the outer teeth 904 in each grass-like region 902. The etching can remove the silver layer on the top surface 924 of the vertically extending teeth 904, thereby exposing the top surface 924 of the teeth 904.

[0099] Each grass-like region 902, including the tooth-like structure 904 and the filler material 930, defines a grass-like bonding pad 940. The top of each grass-like bonding pad 940 may have a roughness Ra greater than 15 nm, for example, in the range of 15 nm to 100 nm.

[0100] Furthermore, in some embodiments, a template or needle can be used to deposit the underfill 950, for example, containing epoxy resin. The height of the underfill 950 can be adjusted as needed based on the shape and / or size of the die to be installed into the inserter 900.

[0101] Figure 10A An exemplary electron microscope image of an exemplary grass-like region 902 formed from black silicon, as cited above in “A Survey on the Reactive Ion Etching of Silicon in Microtechnology”, is shown. Figure 10B An exemplary electron microscope image of a single black silicon spiral is shown.

[0102] The multi-material toothed bonding pads disclosed herein can be formed on any suitable integrated circuit device. For example, in Figures 3A to 9B In the exemplary embodiments shown and discussed above, multimaterial toothed bonding pads are formed on a mounting structure (e.g., an interposer or package substrate) to which one or more dies are mounted. In other embodiments, such as using any of the materials and techniques disclosed herein, any of the multimaterial toothed bonding pads disclosed herein may be formed on each die or may be formed on both the die and the mounting structure.

[0103] Furthermore, in some embodiments, the bonding pads configured to bond with the toothed bonding pads according to the present disclosure may have a three-dimensional shape designed to further improve the bonding with the toothed bonding pads, for example, including a three-dimensional shape including a groove or other geometry configured to receive the teeth of the toothed bonding pads.

[0104] For example, Figure 11A and Figure 11BAn exemplary embodiment is shown, wherein each die includes a bonding pad shaped to receive a corresponding multi-material toothed bonding pad on a mounting structure (e.g., an interposer or a package substrate). Figure 11A A mounting structure 1100 is shown that includes multi-material toothed bonding pads 1102, each of which includes an array of teeth 1110 and a filling material 1112 in the space between adjacent teeth 1110. Figure 11A Dies 1140a and 1140b are shown, each including a bonding pad 1142 formed to receive a tooth 1110 disposed on a mounting structure 1100 for a corresponding bonding pad 1102. Specifically, each bonding pad 1142 may include a plurality of protrusions 1144 defining openings or gaps 1146 configured to receive the tooth 1110. The bonding pads 1142 may be formed of aluminum or other suitable metal. In some embodiments, the protrusions 1144 may be tapered, circular, or otherwise configured to facilitate self-alignment of each bonding pad 1142 with its corresponding bonding pad 1102.

[0105] Figure 11B Dies 1140a and 1140b are shown mounted to mounting structure 1100, wherein the teeth 1110 of each bonding pad 1102 are received in an opening or gap 1146 defined between protrusions 1144 of the corresponding bonding pad 1142. Similarly, the protrusions 1144 of the bonding pad 1142 are received in filled spaces 1112 between the teeth 1110 of the bonding pad 1102.

[0106] In some embodiments, metal bumps (e.g., gold pillar bumps) can be applied to bonding pads that engage with multi-material toothed bonding pads according to the present disclosure to further improve the bonding between the respective bonding pads. For example, Figure 12A and Figure 12B An exemplary embodiment is shown in which gold pillar bumps are applied to the bonding pads of a bare die (which is being mounted to a mounting structure having multi-material toothed bonding pads). Figure 12A An exemplary mounting structure 1200 (e.g., an interposer or package substrate) is shown, comprising a multi-material toothed bonding pad 1202 completely covered by a bottom filler region 1210 (e.g., containing epoxy resin). Each multi-material toothed bonding pad 1202 may include an array of aluminum teeth 1204 (each containing aluminum) and a filler material 1206 (containing silver) in the space between adjacent teeth 1204, for example, as discussed above. A die 1220 having one or more solid aluminum bonding pads 1222 may include gold pillar bumps 1230 formed on or attached to each bonding pad 1222.

[0107] Figure 12BA bare die 1220 is shown mounted to a mounting structure 1200, wherein gold bumps penetrate an underfill region 1210 (e.g., epoxy resin) and enter a silver-filled space 1206 between the teeth 1204 of each bonding pad 1202. A thermo-ultrasonic bonding process can be performed, which can form eutectic bonds between each gold bump 1230 and the aluminum and silver of each bonding pad 1202. The underfill region 1210 can provide a moisture seal for the mounted structure.

Claims

1. An integrated circuit (IC) device, comprising: Metal circuits; as well as A multi-material toothed bonding pad, the multi-material toothed bonding pad being connected to the metal circuit, the multi-material toothed bonding pad comprising: A plurality of vertically extending teeth formed of a first material, wherein an oxide layer is formed on each of the respective vertically extending teeth; and A filler material is located between the plurality of vertically extending teeth formed of a second material different from the first material; The plurality of vertically extending teeth define a grinding structure for facilitating bonding of another structure to the multi-material toothed bonding pad.

2. The integrated circuit (IC) device according to claim 1, wherein the integrated circuit (IC) device includes an interpolator.

3. The integrated circuit (IC) device according to claim 1, wherein the integrated circuit (IC) device comprises an IC die.

4. The integrated circuit (IC) device of claim 1, wherein the oxide layer formed on the respective vertically extending teeth defines the polishing structure.

5. The integrated circuit (IC) device of claim 1, wherein the first material comprises aluminum and the second material comprises silver.

6. The integrated circuit (IC) device of claim 1, wherein the first material comprises silicon.

7. The integrated circuit (IC) device of claim 1, wherein a corresponding vertically extending tooth of the plurality of vertically extending teeth has a height-to-width ratio of at least 2.

8. The integrated circuit (IC) device of claim 1, wherein a corresponding vertically extending tooth of the plurality of vertically extending teeth has a height-to-width ratio in the range of 3 to 5.

9. The integrated circuit (IC) device of claim 1, wherein a respective vertically extending tooth of the plurality of vertically extending teeth includes a silicon junction at an exposed surface of the vertically extending tooth.

10. A method for forming multi-material toothed bonding pads, the method comprising: Forming a layer of the first material; The layer of the first material is etched to define (a) a plurality of vertically extending teeth formed of the first material and (b) an open space between the plurality of vertically extending teeth, wherein an oxide layer is formed on the respective vertically extending teeth; A layer of second material is deposited on the plurality of vertically extending teeth and extends downward into the open space between the plurality of vertically extending teeth; as well as Remove a portion of the second material from the plurality of vertically extending teeth to expose the upper surface of the plurality of vertically extending teeth; The oxide layer formed on the corresponding vertically extending teeth defines a polishing structure for facilitating bonding of another structure to the multi-material toothed bonding pad.

11. The method of claim 10, wherein Removing a portion of the second material from the plurality of vertically extending teeth to expose the upper surface of the plurality of vertically extending teeth includes: Etch portions of the second material on the plurality of vertically extending teeth to expose the upper surfaces of the plurality of vertically extending teeth.

12. The method of claim 10, wherein the first material comprises aluminum and the second material comprises silver.

13. The method of claim 10, further comprising performing a roughening process to increase the surface roughness of the plurality of vertically extending teeth.

14. A bonding pad formed by any one of the methods according to claims 10 to 13.

15. A bonding method, comprising: A first IC device is provided, including a first integrated circuit (IC) device bonding pad, the first IC device bonding pad comprising: A plurality of oxidized teeth, each oxidized tooth comprising a vertically extending tooth formed of a first material and a first oxide layer formed on said vertically extending tooth; and A second material, disposed in the space between the plurality of oxidized teeth, is different from the first material; The plurality of oxidized teeth define a grinding structure; and A bonding process is performed to bond the first IC device bonding pad of the first IC device to the second IC device bonding pad of the second IC device, the second IC device bonding pad having a second oxide layer formed thereon. During the bonding process, the abrasive structure defined by the plurality of oxide teeth of the bonding pads of the first IC device interacts with the second oxide layer formed on the bonding pads of the second IC device to wear, break, or remove the first oxide layer formed on the vertically extending teeth and the second oxide layer formed on the bonding pads of the second IC device.

16. The bonding method of claim 15, wherein the bonding process includes applying ultrasonic energy to at least one of the first IC device bonding pad and the second IC device bonding pad.

17. The bonding method of claim 15, wherein the bonding process includes applying ultrasonic energy and heat to at least one of the first IC device bonding pad and the second IC device bonding pad using a thermo-ultrasound device.

18. The bonding method of claim 15, wherein the bonding process causes eutectic bonding between the first IC device bonding pad and the second IC device bonding pad.

19. The bonding method of claim 15, wherein the bonding process causes (a) the first material forming the vertically extending teeth of the first IC device bonding pad, (b) the second material disposed in the space between the plurality of vertically extending teeth, and (c) eutectic bonding between the second IC device bonding pads.

20. The bonding method according to claim 19, wherein: The first material contains aluminum; The second material contains silver; and The second IC device bonding pad contains aluminum.

21. A combined integrated circuit device manufactured by the bonding method according to any one of claims 15 to 20.

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