Piezo Solutions for Semiconductor Wafer Production

Piezo based actuators and nanopositioning systems from piezosystem jena are key technologies in semiconductor manufacturing, enabling precise control at nanometer and sub-nanometer levels. Their high stiffness, fast dynamic response, and excellent thermal stability make them essential for wafer processing, lithography alignment, inspection, and packaging steps. With closed-loop feedback and cleanroom-compatible designs, these systems support the increasing precision and throughput requirements of advanced semiconductor production processes.

Figure 1. Each large step of the semiconductor manufacturing process is shown. Silicon ingots are processed into wafers during step 1, dice are fabricated during the front-end of the process, and finally dice are packed into packaged device during back-end packaging.

Wafer Processing (From Silicon to Wafer)

In the initial stage of transforming silicon ingots into wafers, piezoelectric systems play a crucial role in ensuring precision and quality.

Wafer Slicing and Polishing: Piezo based positioning systems are utilized in both the slicing and polishing steps of wafer fabrication. During slicing, maintaining consistent and precise wafer thickness (ranging from 280 to 725 micrometers) is critical. Objective lens positioners, like the MIPOS series offer sub-nanometer resolution, enabling dynamic monitoring of the entire wafer depth without introducing vibrations common in traditional systems. When integrated into feedback control systems, these positioners allow for real-time adjustments which ensure uniform slicing and immediate imaging of any defects for process improvement.

Wafer Polishing: Following the wafer slicing process, piezo based actuators like the Series PA can control the pressure of polishing instruments on the silicon wafer surface. This precise control helps improve surface smoothness, reduce defect densities, and minimize wafer warpage.

Wafer Inspection: Multi axis stages, such as piezosystem jena’s TRITOR series are also crucial in wafer inspection. Piezo objective positioners provide excellent autofocusing solutions for microscopy, crucial for identifying defects and ensuring wafer quality. Critically in this process there are highly stable motion profiles and minimized cross axis talk.

Front-End Fabrication (From Wafer to Die)

During the complex process of creating individual dice on the wafer, piezoelectric systems are implemented in various critical steps.

Lithography: In EUV lithography machines (like the ones from ASML), piezos are absolutely crucial for extreme precision movement and positioning. Piezos are used in the nanometer-level positioning of the wafer and the mask (reticle), where they allow ultra-fast, high-accuracy adjustments while actively dampening vibrations caused by machine operation. A further application is perfect alignment of mirrors, via real time adjustment for tilt, focus and shape correction. In DUV lithography machines, 3-dimensional piezoelectric positioning stages are used to align heavy 300mm wafers on wafer chucks with sub-nanometer resolution. Precise wafer orientation is vital during the lithography process to prevent defects and maximize die yield.

Chemical Vapor Deposition (CVD): A new application involves using compact piezoelectric stack actuators as valve devices within the chemical plumbing of CVD machinery. These actuators enable fast, precise, and consistent delivery of finely vaporized chemicals for depositing sub-micron-thick photoresist layers onto the silicon wafer. Their high operational lifespan without wear or misalignment is advantageous for continuous processing. The characteristics of piezo systems; High force, fast response, no backlash, ultra-fine movement, provide a specific advantage in this application.

Inspection and Defect Detection Systems: Piezoelectric positioning systems are indispensable in high-precision semiconductor inspection applications, offering nanometer-level control, high dynamic response, and excellent stability.

Mask Inspection: Piezoelectric objective scanners enable rapid, high-resolution inspection of photomasks, detecting sub-micron and nanometer-scale defects in critical pattern features before wafer exposure. Multi-axis piezo stages (XYZ motion, tip and tilt, like piezosystems jena’s PENTOR series) ensure precise positioning and scanning of the photomask surface at high throughput, maintaining system stability even under continuous dynamic operation.

Defect Inspection: In wafer-level defect inspection, piezo-driven nanopositioning stages and objective actuators enable fast, large-area scanning with high repeatability. Their high stiffness, minimal hysteresis, and dynamic linearity are essential for detecting and classifying pattern defects, critical dimension (CD) variations, and particle contamination. Closed-loop piezo stages, using capacitive or strain gauge sensors, maintain consistent sub-nanometer positioning over extended inspection cycles, improving system reliability and reducing false defect rates. Piezosystem jena has developed its TRITOR series with CAP sensor for the highest position stability and linearity in motion.

E-beam Inspection: For advanced node devices (5 nm and below), E-beam inspection systems utilize piezo wafer stages to precisely align and scan individual die under a finely focused electron beam. Piezo objective positioners, like the MIPOS embedded in the E-beam column continuously adjust lens elements and beam steering optics to maintain focal precision at sub-nanometer scales. This enables accurate defect localization at atomic dimensions while minimizing drift, beam blur, and inspection time. Additionally, fast response piezo actuators enhance throughput in multi-beam E-beam systems by enabling rapid field stitching and beam stabilization.

Key Technical Advantages of Piezo Systems in Inspection:

Sub-nanometer precision for critical feature detection

High-speed dynamic response (>1 kHz bandwidths in some designs)

Minimal thermal drift, essential for long inspection runs

Low particle generation for cleanroom compatibility

Closed-loop control with nanometer-level feedback accuracy

Vibration Control: Piezoelectric actuators can be used to mitigate electrical noise and vibrations generated during various inspection steps. By introducing counter-actuation, they help minimize additional defects or abnormalities caused by environmental noise or machinery operation, with actuation frequencies ranging from 5-70kHz, an incredible speed realized by piezosystem jena’s hpower actuators.

Back-End Packaging (From Die to Completed Device)

In the final stage of packaging diced silicon, piezo based motion systems offer solutions for fine-pitch bonding and device cleaning.

Wire Bonding: Piezoelectric actuators are used to generate ultrasonic frequencies necessary for creating durable and miniature metallurgical bonds between individual dies and the lead frame using fine aluminum or gold wires. These miniature actuators provide high-repeatability ultrasonic signals with tunable frequency responses to accommodate varying wire bonding requirements.

Device Cleaning: Piezoelectric technology guarantees advanced device cleaning, particularly for confined hidden surfaces in 3D NAND and deep DRAM capacitors. High-powered piezoelectric actuators and shakers can enhance bubble cavitation technologies by providing precise signal outputs and compact device sizes. While megasonic frequencies are often used, piezoelectric systems can offer more precise frequency control within a smaller bandwidth, potentially improving the productivity and efficiency of the cavitation process for cleaning complex 3D structures and high aspect ratios without damaging delicate features. Outstanding here is the piezo based shaker from piezosystem jena’s hpower series PiSha with working frequencies of 100kHz, even past its own resonant frequency.