In the field of semiconductor manufacturing, chip processing scenarios in high-temperature environments (such as diffusion, annealing, welding and other processes) pose severe challenges to fixture performance. The semiconductor chip fixture not only needs to maintain precise clamping and positioning at high temperatures to prevent chip displacement or falling off, but also ensure that the material itself does not undergo thermal deformation, oxidation or chemical corrosion to maintain process stability and chip yield. This process involves multidisciplinary collaboration such as material science, thermal design, and structural mechanics, and is a key link in ensuring the reliability of advanced processes.
The clamping stability of semiconductor chip fixtures in high-temperature environments first depends on the precise matching of thermal expansion coefficients. The thermal expansion coefficient of semiconductor chips (such as silicon-based chips) is usually 2.6~3.0×10⁻⁶/℃. If the fixture material is too different from it, stress will be generated due to different expansion rates at high temperatures, resulting in changes in clamping force or chip cracking. For example, when using Invar (thermal expansion coefficient of about 1.5×10⁻⁶/℃) or ceramic-based composite materials (such as Al₂O₃ ceramics, thermal expansion coefficient of about 7×10⁻⁶/℃), it is necessary to compensate for the difference through composite structure design (such as gradient material transition layer) so that the fixture and the chip can maintain coordinated deformation during the heating process to avoid interface stress concentration.
The high-temperature mechanical properties of the material are another core element. Ordinary metal fixtures tend to soften at high temperatures, resulting in attenuation of the clamping force. For this reason, high-temperature alloys (such as nickel-based superalloys) or refractory metals (such as tungsten and molybdenum) are preferred. Such materials can still maintain a high yield strength above 1000℃ and have excellent creep resistance. For example, in the semiconductor annealing process (800~1200℃), the molybdenum alloy fixture can be further improved in hardness and oxidation resistance through surface nitriding treatment to ensure that the clamping structure does not undergo plastic deformation at high temperatures for a long time. In addition, ceramic materials are often used in extreme high temperature scenarios due to their high melting point and chemical inertness, but their brittleness needs to be improved through micro-nanostructure design to avoid cracking due to thermal shock.
Heat conduction and heat dissipation design are crucial to the stability of semiconductor chip fixtures. In a high temperature environment, if the fixture cannot export heat in time, it may cause local overheating, causing chip performance degradation or fixture material failure. By embedding heat pipes or microchannel water cooling structures in the fixture matrix, heat can be quickly transferred to the external temperature control system. For example, in the flip-chip soldering process, the fixture base uses a copper-diamond composite material (thermal conductivity > 600W/m·K), and with the air-cooling nozzle on the top, the local temperature fluctuation of the chip can be controlled within ±2°C, while avoiding thermal deformation of the fixture due to overheating.
Surface interface engineering is a key technical path to improve material reliability. At high temperatures, the contact interface between the fixture and the chip is prone to oxidation or element diffusion, affecting the clamping force and chip cleanliness. Diamond-like carbon (DLC) coating or precious metal (such as gold, platinum) film is prepared on the surface of the fixture by physical vapor deposition (PVD), which can form an anti-oxidation barrier and reduce the interface friction coefficient (<0.1) to ensure stable clamping force. For scenarios where insulation is required, silicon nitride (Si₃N₄) coating can provide high-temperature dielectric properties to avoid leakage risks. In addition, interface micro-nano texturing (such as lattice pits or grooves) can improve clamping reliability by increasing the mechanical interlocking effect, especially for low adhesion interfaces such as lead-free solder.
Dynamic monitoring and adaptive adjustment technology provides an intelligent solution for high-temperature fixtures. The micro-thermocouples and strain sensors integrated in the fixture can monitor the temperature field and clamping force changes in real time, and dynamically adjust the pressure of the pneumatic or electric clamping module through a closed-loop control system. For example, in the rapid thermal annealing (RTA) process, when the temperature rises to the target value, the piezoelectric ceramic-driven clamping arm can automatically compensate for the gap caused by the thermal expansion of the material to maintain a constant clamping force. This adaptive mechanism can not only cope with the chip size differences between batches, but also optimize the clamping strategy through machine learning algorithms to improve process repeatability.
In industry practice, multi-material composite structures have become the mainstream design idea for high-temperature fixtures. Taking a 3nm process chip packaging fixture as an example, its main frame uses Invar alloy to control thermal expansion, the clamping claws that contact the chip use silicon carbide (SiC) ceramics to resist wear, the internal embedded nickel-chromium alloy heating wire to achieve local temperature control, and the surface is covered with graphene coating to enhance heat dissipation. This composite design of "external stability, internal temperature control, and surface wear resistance" enables the fixture to maintain a positioning accuracy of ±5μm at a high temperature of 1100℃, meeting the extreme requirements of advanced processes for clamping stability and material reliability.
As semiconductor processes develop towards higher temperatures and more refinement, the material and structural innovation of semiconductor chip fixtures will continue to break through. In the future, the combination of nanomaterials (such as carbon nanotube reinforced composites) and additive manufacturing technology may realize an integrated fixture with high strength, low expansion and complex internal cooling structure, further improving reliability in high temperature environments. At the same time, ultra-thin film coating technology based on atomic layer deposition (ALD) will provide more precise atomic-level control means for interface protection, and promote semiconductor manufacturing towards higher efficiency and lower defect rate.
