Ultrahigh vacuum normal-temperature bonding equipment
By using an ultra-high vacuum room temperature bonding device to perform metal bonding at room temperature, the problem of narrow process window for TCB copper-copper interconnects is solved, achieving stable metal bonding and high-precision alignment, which is suitable for high-density integration scenarios such as 3D-IC and Chiplet.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SABERS CO LTD
- Filing Date
- 2026-03-06
- Publication Date
- 2026-04-24
AI Technical Summary
The narrow window of the TCB copper-copper interconnect process means that abnormal temperatures can lead to uncontrolled copper atom diffusion, chip thermal damage, structural deformation, and decreased process consistency, affecting alignment accuracy and interconnect reliability.
The ultra-high vacuum room temperature bonding equipment is used to perform metal bonding in an ultra-high vacuum environment at room temperature. A plasma activation device is used to remove the metal oxide layer, and a vision alignment module is used to achieve precise alignment, ensuring atomic-level cleanliness of the metal interface and avoiding problems caused by high temperature.
Achieving robust metal bonding at room temperature avoids issues such as diffusion runaway, thermal damage, and reduced alignment accuracy caused by high temperatures, broadens the process window, and improves interconnect reliability and process stability, making it suitable for high-density integration scenarios.
Smart Images
Figure CN121925147A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor device bonding technology, and in particular to an ultra-high vacuum room temperature bonding device. Background Technology
[0002] Copper-to-copper interconnect (Cu-Cu TCB) is a core technology in advanced semiconductor packaging that enables solderless copper-to-copper direct diffusion connections between chips and substrates through thermocompression bonding. It is based on local heating, rapid temperature rise and fall, and high-precision alignment. By raising the copper to a set temperature and simultaneously applying pressure, copper atoms diffuse to form a stable connection. It is suitable for ultra-fine pitches of <10μm and supports high-density integration scenarios such as 3D-IC and Chiplet. It also has the advantages of low resistance, high reliability, and process compatibility.
[0003] The main limitation of TCB copper-copper interconnects lies in their narrow process window, requiring a balance between temperature, pressure, time, and alignment accuracy, making parameter optimization complex. Temperature, in particular, significantly impacts the chip; abnormal temperatures disrupt the controllable diffusion of copper atoms, either preventing metallurgical bonding due to insufficient diffusion or causing microstructure degradation due to excessive diffusion. This leads to derivative problems such as device thermal damage, structural deformation, and decreased process consistency. Temperature also causes thermal deformation, thermal stress, and system thermal drift in the chip, resulting in decreased alignment accuracy. In high-bump-density copper-copper interconnects, this can lead to bump misalignment, insufficient contact area, and ultimately interconnect failure. Summary of the Invention
[0004] The purpose of this invention is to provide an ultra-high vacuum room temperature bonding device for performing metal bonding interconnection between chips and substrates in a room temperature environment.
[0005] To achieve this objective, the present invention adopts the following technical solution:
[0006] An ultra-high vacuum room temperature bonding device includes:
[0007] The bonding cavity is equipped with a wafer stage module, which is used to support and fix the wafer.
[0008] The pressure head module, which is opposite to the wafer stage module, is configured to pick up the chip and bond the chip to the wafer surface at room temperature.
[0009] The chip transmission module is configured to transfer chips;
[0010] The chip transfer mechanism is configured to transfer chips between the unloading position of the chip transfer module and the picking position of the pressure head module.
[0011] A vision alignment module is used to obtain the relative positional deviation between the chip and the alignment marks on the wafer;
[0012] The controller is used to coordinate the execution timing of the above modules;
[0013] Also includes:
[0014] The activation chamber, connected to the bonding chamber via a transfer chamber, is configured to perform activation processing on the chip and / or wafer surface;
[0015] The transfer cavity is configured to perform vacuum transfer of chips and / or wafers between the activation cavity and the bonding cavity;
[0016] A vacuum maintaining system is configured to be sealed to the bonding cavity, the activation cavity, and the transfer cavity, enabling the bonding cavity, the activation cavity, and the transfer cavity to independently maintain an ultra-high vacuum environment, wherein the vacuum degree of the ultra-high vacuum environment is ≤6×10⁻⁶. -6 Pa.
[0017] Preferably, the vacuum level of the ultra-high vacuum environment is 6×10⁻⁶. -6 Up to 1×10 -9 Pa, including but not limited to 1×10 - 7 Pa, 5×10 -7 Pa, 1×10 -8 Pa, 5×10 -8 Pa.
[0018] Preferably, the vacuum maintaining system includes a vacuum pump assembly; the vacuum pump assembly includes a backing pump and a main pump; the backing pump is configured as a dry vacuum pump; the main pump is configured as a cold pump, a molecular pump, or a cold pump-molecular pump combination pump.
[0019] Preferably, the bonding cavity, the activation cavity, and the transfer cavity are each equipped with a vacuum maintenance system independently.
[0020] Preferably, the activation chamber includes a plasma activation device or an H radical activation device.
[0021] Preferably, the plasma source of the plasma activation device is an inductively coupled plasma, a capacitively coupled plasma, or a fast atomic beam source;
[0022] The H radical activation device includes a steam generation unit, a catalytic unit, and a gas path control unit, or the H radical activation device includes an H2 plasmaization unit and a gas path control unit.
[0023] Preferably, the activation process includes removing the oxide layer of the metal to be bonded on the chip and / or wafer surface;
[0024] The metal to be bonded includes at least one of gold, silver, copper, copper-tin alloy, silver-tin alloy, and tin-silver-copper alloy.
[0025] Preferably, a transfer cavity with a sealed connection is further provided between the bonding cavity and the transfer cavity;
[0026] The transfer cavity includes an actuator configured to transfer a chip and / or wafer between the transfer cavity and the bonding cavity;
[0027] The transfer cavity is maintained in an ultra-high vacuum environment consistent with that of the transfer cavity and the bonding cavity by the vacuum maintenance system.
[0028] Preferably, it further includes an inert gas backfilling device, which is independently connected to the bonding cavity, the activation cavity and / or the transfer cavity.
[0029] Preferably, it also includes a front-end module, which is sealed to the transfer chamber via a vacuum valve and is used for the transfer and storage of chips, wafers and bonded products.
[0030] This invention provides an ultra-high vacuum room temperature bonding device that can achieve unheated metal interface bonding (such as copper-copper bonding) between chips and wafers in a room temperature environment such as 0-40℃. The device can complete the surface activation of the interface to be bonded in an ultra-high vacuum environment, effectively remove the metal oxide layer, and complete the transfer and bonding operations in an ultra-high vacuum environment. By suppressing and delaying the secondary formation of the metal oxide layer in the ultra-high vacuum environment, the metal interface to be bonded meets the core conditions for atomic diffusion, and finally forms a stable bonding interface at room temperature. This equipment completely avoids the series of problems caused by high temperatures in traditional TCB metal interconnect hot pressing processes. It avoids uncontrolled atomic diffusion caused by abnormal temperatures (insufficient diffusion prevents effective bonding, while excessive diffusion causes microstructure degradation), and eliminates defects such as chip thermal damage, structural deformation, system thermal drift, and decreased process consistency caused by high temperatures. At the same time, it eliminates the problem of reduced alignment accuracy caused by thermal deformation and thermal stress, effectively solves the interconnect failure risks such as bump misalignment and insufficient contact area in high bump density scenarios, significantly widens the metal interconnect process window, reduces the difficulty of optimizing process parameters such as temperature and pressure, and ensures the connection reliability and process stability of ultra-fine pitch metal interconnects. Attached Figure Description
[0031] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0032] Figure 1 This is a schematic diagram of the structure of the ultra-high vacuum room temperature bonding device provided by the present invention.
[0033] Figure 2 This is a schematic diagram of the internal structure of the bonding cavity in the ultra-high vacuum room temperature bonding device provided by the present invention.
[0034] Figure label:
[0035] 1. Bonding cavity; 2. Transfer cavity; 3. Activation cavity; 4. Transfer cavity; 5. Front-end module; 11. Gantry platform; 12. Pressure head module; 13. Chip transfer mechanism; 14. Wafer stage module; 15. Chip transfer module; 16. Vision alignment module. Detailed Implementation
[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0037] like Figure 1 and Figure 2 As shown, this embodiment provides an ultra-high vacuum room temperature bonding device. The device adopts a modular chamber design to achieve heatless metal bonding between chips and wafers in an ultra-high vacuum environment.
[0038] Reference Figure 1 The device includes a bonding cavity 1, a transfer cavity 2, an activation cavity 3, a transit cavity 4, and a front-end module 5. The bonding cavity 1 is sealed to the transit cavity 4 through the transfer cavity 2, and the activation cavity 3 is also connected to the bonding cavity 1 through the transit cavity 4. The front-end module 5 is sealed to the transit cavity 4 through a vacuum valve and is used for transit storage of chips, wafers, and bonded products.
[0039] Reference Figure 2 The bonding cavity 1 is internally configured with a gantry platform 11, a pressure head module 12, a chip transfer mechanism 13, a wafer stage module 14, a chip transfer module 15, and a vision alignment module 16. The gantry platform 11 spans the interior of the bonding cavity 1, and the pressure head module 12 is mounted on the gantry platform 11 and can move in the XZ directions. The wafer stage module 14 is located below the pressure head module 12 and faces it. The chip transfer module 15 is located on one side of the wafer stage module 14 and is used to supply chips. The chip transfer mechanism 13 is located between the unloading position of the chip transfer module 15 and the picking position of the pressure head module 12, and is used to transfer chips.
[0040] To achieve the atomically clean interface required for room-temperature bonding, this embodiment is equipped with a vacuum maintenance system (not shown in the figure), which is sealed to each chamber.
[0041] The vacuum maintenance system includes a vacuum pump assembly, which consists of a backing pump and a main pump. The backing pump is configured as a dry vacuum pump for initial vacuuming; the main pump is configured as a cold pump, molecular pump, or a combination of cold pump and molecular pump to obtain and maintain an ultra-high vacuum environment.
[0042] Bonding chamber 1, activation chamber 3, and transfer chamber 4 are each equipped with an independent vacuum maintenance system, enabling each chamber to independently maintain an ultra-high vacuum environment. In this embodiment, the vacuum level of the ultra-high vacuum environment is ≤6×10⁻⁶. -6 Pa, preferably 1×10 -7 Up to 1×10 - 9 Pa. This vacuum level can effectively suppress the secondary formation of metal oxide layers, providing the necessary conditions for room temperature bonding.
[0043] In another embodiment, the transfer cavity 2 is also maintained in an ultra-high vacuum environment consistent with that of the transfer cavity 4 and the bonding cavity 1 by a vacuum maintenance system, so as to ensure that the chip and / or wafer are always under ultra-high vacuum protection during the transfer between the chambers.
[0044] The activation chamber 3 is configured to perform activation processing on the chip and / or wafer surface to remove the oxide layer on the surface of the metal to be bonded. In this embodiment, the activation chamber 3 includes a plasma activation device or an H radical activation device.
[0045] When a plasma activation device is used, the plasma source is inductively coupled plasma (ICP) or capacitively coupled plasma (CCP). Plasma activation removes the oxide layer on the metal surface through high-energy particle bombardment or chemical reaction, and can also clean organic pollutants. Preferably, in this embodiment, the plasma gas source is a mixture of hydrogen and argon. The plasma dissociates into H active free radicals, which react with the metal oxides to remove the metal oxide layer.
[0046] As a feasible implementation, the H radical activation device includes a steam generation unit, a catalytic unit, and a gas path control unit. The steam generation unit generates formic acid vapor, and the catalytic unit includes a precious metal mesh (such as a mesh formed of ruthenium (Ru), rhodium (Rh), palladium (Pd), iridium (Ir), platinum (Pt), and gold (Au)) disposed in the gas path. Preferably, a heating unit is provided in the gas path to accelerate catalysis through heating. When the formic acid vapor passes through the precious metal mesh in the gas path, it is catalytically decomposed to generate H radicals, which remove the metal oxide layer through a reduction reaction.
[0047] As another feasible implementation, the H radical activation device includes a plasma unit, which includes a radio frequency discharge module. The radio frequency discharge module ionizes H2 to generate H radicals, and the metal oxide layer is removed through a reduction reaction.
[0048] The activation treatment is suitable for bonding metals including at least one of gold, silver, copper, copper-tin alloy, silver-tin alloy, and tin-silver-copper alloy. After activation, the metal surface is restored to an atomically clean state, free of metal oxide layer. The transport and bonding processes after activation are carried out under ultra-high vacuum, which can suppress secondary oxidation before material bonding and meet the interfacial conditions for atomic diffusion at room temperature during bonding.
[0049] Reference Figure 2 The pressure head module 12 and the wafer stage module 14 are arranged opposite each other to form a bonding actuator.
[0050] The pressing head module 12 includes a driving unit and a chip adsorption unit. The driving unit can drive the chip adsorption unit to move in the Z direction, realizing the chip picking and pressing action. The chip adsorption unit is used to adsorb the chip at the picking position and press the chip onto the wafer surface. The picking position of the pressing head module 12 refers to the handover position where the chip is waiting to be picked up by the pressing head module 12 after being flipped by the chip transfer mechanism 13.
[0051] The wafer stage module 14 includes a wafer chuck, the surface of which can selectively form an adsorption force to adsorb the non-bonded surfaces of the wafer. The wafer chuck is configured to fix the wafer by electrostatic adsorption, preventing wafer displacement during bonding. The surface of the wafer chuck has limiting protrusions that abut against the sidewalls of the wafer, thereby limiting the wafer's position and ensuring accurate wafer positioning.
[0052] In one embodiment, the wafer stage module 14 further includes a hinged first mounting plate and a second mounting plate. A wafer chuck is disposed on the first mounting plate, and the second mounting plate is mounted on the gantry platform 11. The first mounting plate and the second mounting plate are hinged via a six-axis displacement platform.
[0053] The six-axis displacement platform is a motion mechanism with six degrees of freedom for translation and rotation. This structure enables multi-degree-of-freedom active adjustment of the wafer's orientation, allowing the wafer chuck to compensate for its spatial angles and positions even after mounting, thereby correcting for wafer planar deviations or mounting tilts. This ensures that the wafer's bonding surface remains perpendicular to the motion axes of the pressure head module 12, providing the necessary planar reference for subsequent chip bonding and directly improving the overall bonding positional accuracy and process consistency.
[0054] The vision alignment module 16 is used to acquire the relative positional deviation between the chip and the wafer alignment marks. Based on the characteristics of the bonding material, this embodiment provides two optional solutions:
[0055] Option 1: Coaxial Camera System
[0056] The vision alignment module 16 includes a support, a moving platform, and a coaxial camera. The coaxial camera is mounted on the support via the moving platform and can move in the X and Y directions. The support is mounted on the gantry platform 11. This structure uses the coaxial camera to acquire images of the chip alignment marks and the wafer alignment marks and calculates the positional deviation.
[0057] Option 2: Transmitted Light Camera System
[0058] The vision alignment module 16 is a transmission light camera integrated into the pressure head module 12. This camera is an infrared camera, which can utilize the characteristic of infrared light to penetrate semiconductor materials to perform imaging recognition with wafer alignment marks through the markings on the back of the chip, thereby achieving high-precision penetrating alignment.
[0059] The chip transfer module 15 is configured to transfer chips from a storage location to a predetermined unloading location. The chip transfer module 15 includes a carrier section for carrying an activated chip tray on which multiple chips are placed.
[0060] The chip transfer mechanism 13 is configured to transfer chips between the unloading position of the chip transfer module 15 and the picking position of the pressure head module 12. The chip transfer mechanism 13 includes a chip holding unit that can hold chips in the chip tray of the chip transfer module 15 and flip the chips around an axis to facilitate picking by the pressure head module 12.
[0061] The workflow of the ultra-high vacuum room temperature bonding equipment provided in this embodiment is as follows:
[0062] S1: The chip and wafer in the front-end module 5 enter the transfer chamber 4 through the vacuum valve;
[0063] S2: The actuator in the transfer chamber 4 successively transfers the chip and wafer to the activation chamber 3;
[0064] S3: Activation chamber 3 activates the chip and wafer surface to remove the oxide layer on the surface of the metal to be bonded (such as copper);
[0065] S4: The activated chip and wafer enter the bonding cavity 1 via transfer cavity 4 and transmission cavity 2;
[0066] S5: Chip transmission module 15 transmits the chip to the predetermined unloading position;
[0067] S6: The chip holding unit of the chip transfer mechanism 13 adsorbs the chip and flips it to the material picking position of the pressure head module 12;
[0068] S7: The chip adsorption part of the pressure head module 12 adsorbs the chip at the material pick-up position;
[0069] S8: The vision alignment module 16 identifies the relative position of the chip and the alignment mark on the wafer and calculates the positional deviation;
[0070] S9: Based on the positional deviation, the pressure head module 12 adjusts its position in the XZ direction, or the wafer stage module 14 adjusts the wafer orientation through a six-axis displacement platform to achieve precise alignment;
[0071] S10: After alignment, at room temperature (0-40℃), the driving part of the pressure head module 12 drives the chip adsorption part to descend, pressing the chip onto the wafer surface to form a metal-metal direct bond.
[0072] S11: Press head module 12 releases the chip and resets, completing a single bonding operation;
[0073] S12: Repeat steps S5-S11 until the bonding of all chips on the wafer is completed;
[0074] S13: The bonded product is returned to the front-end module 5 via the chip transmission module 15 or a dedicated transmission mechanism.
[0075] Throughout the above process, bonding cavity 1, activation cavity 3, transfer cavity 4, and transport cavity 2 are maintained in an ultra-high vacuum environment (vacuum degree ≤ 6 × 10⁻⁶). -6 Pa, preferably 1×10 -7 Up to 1×10 -9 Pa) suppresses the secondary formation of metal oxide layers, ensuring atomic-level cleanliness and bonding reliability of the bonding interface at room temperature.
[0076] In another embodiment, the equipment also includes an inert gas backfilling device (not shown in the figure), which includes an inert gas source, pipelines, and valves. This device is independently connected to the bonding chamber 1, the activation chamber 3, and / or the transfer chamber 4. Under specific process requirements, high-purity inert gas (such as nitrogen or argon) can be backfilled in an ultra-high vacuum environment. A dynamic equilibrium pressure is formed by continuous evacuation and continuous gas intake, creating an inert gas protective atmosphere. The ultra-high vacuum combined with the inert gas strictly controls the water and oxygen in the chamber, further preventing oxidation of the metal surface.
[0077] The ultra-high vacuum room-temperature bonding equipment provided in this embodiment achieves the following technical effects through the above-mentioned technical solution: Completely avoids high-temperature defects: Copper-copper and other metal bonding is completed at room temperature (0-40℃), avoiding problems such as uncontrolled atomic diffusion, chip thermal damage, structural deformation, system thermal drift, and decreased process consistency caused by abnormal temperature in traditional TCB hot pressing processes. Eliminates thermally induced alignment errors: Eliminates the problem of reduced alignment accuracy caused by thermal deformation and thermal stress, effectively solving the potential interconnect failure risks such as bump misalignment and insufficient contact area in high bump density scenarios. Widens the process window: Significantly widens the metal interconnect process window, reducing the difficulty of optimizing process parameters such as temperature and pressure. Stably achieves ultra-fine pitch metal interconnects, supporting high-density integration scenarios such as 3D-IC and Chiplet.
[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. An ultra-high vacuum room temperature bonding device, characterized in that, include: The bonding cavity (1) is equipped with a wafer stage module (14), which is used to support and fix the wafer; The pressure head module (12), which is opposite to the wafer stage module (14), is configured to pick up the chip and bond the chip to the wafer surface at room temperature; The chip transmission module (15) is configured to transfer chips; The chip transfer mechanism (13) is configured to transfer chips between the unloading position of the chip transfer module (15) and the picking position of the pressure head module (12); A vision alignment module (16) is used to obtain the relative positional deviation between the chip and the wafer alignment mark; The controller is used to coordinate the execution timing of the above modules; Also includes: The activation chamber (3), connected to the bonding chamber (1) via the transfer chamber (4), is configured to perform activation processing on the chip and / or wafer surface; The transfer cavity (4) is configured to perform vacuum transfer of chips and / or wafers between the activation cavity (3) and the bonding cavity (1); A vacuum maintaining system is configured to be sealed to the bonding cavity (1), the activation cavity (3), and the transfer cavity (4), such that at least the bonding cavity (1) and the activation cavity (3) independently maintain an ultra-high vacuum environment, wherein the vacuum degree of the ultra-high vacuum environment is ≤6×10⁻⁶. -6 Pa.
2. The ultra-high vacuum room temperature bonding equipment according to claim 1, characterized in that, The vacuum level of the ultra-high vacuum environment is 6×10⁻⁶. -6 Up to 1×10 -9 Pa.
3. The ultra-high vacuum room temperature bonding equipment according to claim 1, characterized in that, The vacuum maintenance system includes a vacuum pump assembly; the vacuum pump assembly includes a backing pump and a main pump; the backing pump is configured as a dry vacuum pump; the main pump is configured as a cold pump, a molecular pump, or a cold pump-molecular pump combination pump.
4. The ultra-high vacuum room temperature bonding equipment according to claim 3, characterized in that, The bonding cavity (1), the activation cavity (3), and the transfer cavity (4) are each independently equipped with the vacuum maintenance system.
5. The ultra-high vacuum room temperature bonding equipment according to claim 1, characterized in that, The activation chamber (3) includes a plasma activation device or an H radical activation device.
6. The ultra-high vacuum room temperature bonding equipment according to claim 5, characterized in that, The plasma source of the plasma activation device is inductively coupled plasma, capacitively coupled plasma, or a fast atomic beam source. The H radical activation device includes a steam generation unit, a catalytic unit, and a gas path control unit, or the H radical activation device includes an H2 plasmaization unit and a gas path control unit.
7. The ultra-high vacuum room temperature bonding equipment according to claim 1 or 6, characterized in that, The activation process includes removing the oxide layer of the metal to be bonded on the chip and / or wafer surface; The metal to be bonded includes at least one of gold, silver, copper, copper-tin alloy, silver-tin alloy, and tin-silver-copper alloy.
8. The ultra-high vacuum room temperature bonding equipment according to claim 1, characterized in that, A sealed transmission cavity (2) is also provided between the bonding cavity (1) and the transfer cavity (4). The transfer cavity (2) includes an actuator configured to transfer a chip and / or wafer between the transfer cavity (4) and the bonding cavity (1); The transmission cavity (2) is maintained in an ultra-high vacuum environment consistent with that of the transfer cavity (4) and the bonding cavity (1) by the vacuum maintenance system.
9. The ultra-high vacuum room temperature bonding equipment according to claim 1 or 2, characterized in that, It also includes an inert gas backfilling device, which is independently connected to the bonding chamber (1), the activation chamber (3) and / or the transfer chamber (4).
10. The ultra-high vacuum room temperature bonding equipment according to claim 1, characterized in that, It also includes a front-end module (5), which is sealed to the transfer chamber (4) through a vacuum valve and is used for the transfer storage of chips, wafers and bonded products.