Optical and semiconductor precision inspection equipment relies heavily on stable optical paths, weak electrical signal acquisition and high-precision grating position feedback. A large number of optical lenses, CCD/CMOS image sensors, laser interferometry components and magnetic sensitive sensors are installed inside the equipment. If structural components are magnetic, stray magnetic fields will occur, interfering with signal acquisition, causing image distortion and measurement drift, and even affecting the interpretation of wafer micro-structure inspection results. Ordinary metal beams are generally magnetic. Although some alloys are demagnetized, they tend to generate residual magnetism again under long-term alternating motion and vibration impact. UNPARALLELED Group develops non-magnetic precision granite beams. Taking advantage of the natural non-magnetic property of stone, together with exclusive ultra-precision machining technology, these beams meet the dual requirements of non-magnetism and stable motion reference for optical and semiconductor inspection equipment.
1. Natural non-magnetic substrate: Eliminate stray magnetic field interference from the source
Most granite contains few ferromagnetic minerals and will not be magnetized or retain residual magnetism after special screening for non-magnetic granite blanks. Unlike metal components, its magnetic field will not drift with vibration or temperature changes. In scenarios such as semiconductor wafer inspection and optical interferometry, magnetically sensitive components are integrated inside the equipment. Even weak stray magnetic fields may cause laser path deviation and grating reading jumps, impairing the repeatability of micron and sub-micron measurement. UNPARALLELED adds magnetic sampling inspection when raw stone arrives at the factory to eliminate blanks mixed with ferromagnetic minerals, ensuring the whole beam remains non-magnetic. Finished products require no additional demagnetization treatment and have no risk of becoming magnetic again under impact, providing a clean magnetic environment for optical paths and sensing systems.
2. Multi-physics synergistic performance: Stable motion reference beyond non-magnetism
Non-magnetism is only a basic requirement. Optical and semiconductor inspection equipment also imposes strict requirements on thermal stability, dynamic rigidity and vibration suppression of beams. With a low thermal expansion coefficient, non-magnetic precision granite beams undergo minimal dimensional change caused by temperature rise from motors and optical components during long continuous operation, effectively preventing thermal drift of mounting reference for guide rails and linear scales. The high material damping absorbs vibration generated during high-speed reciprocation of slides and prevents vibration from transferring to optical lenses and blurring images. In the design phase, UNPARALLELED carries out dynamic and thermal simulation to optimize beam cross-section according to travel range, slide load and acceleration of inspection equipment. It balances high rigidity and self-weight to reduce the load of linear motors and dynamic deflection caused by motion inertia. Either monolithic or precision assembled structures can be selected for small-travel high-precision optical inspection or large-format wafer scanning equipment.
3. Clean precision machining and non-magnetic embedding process for inspection module assembly
The internal space of optical and semiconductor clean chambers requires high cleanliness. Meanwhile, beams need to carry many optical bases, linear scales and sensor mounts. Conventional metal embedded fasteners carry magnetic risks. UNPARALLELED adopts non-magnetic embedded sleeves for non-magnetic granite beams, matched with non-magnetic fasteners and low-volatility special adhesive. All assembly components stay non-magnetic and will not introduce local magnetic fields. Reference surfaces of beams are nano-lapped in a constant-temperature vibration-isolated workshop to strictly control straightness, parallelism and flatness. After machining, beams go through dust-free cleaning to remove lapping dust and debris and avoid particle contamination on wafers and optical lenses. Hole layout is optimized via stress simulation to prevent stress concentration caused by densely arranged holes and local stone deformation during bolt tightening. Edges are passivated to reduce dust accumulation dead corners, suitable for installation inside clean chambers.
4. Working condition adaptation for multiple optical and semiconductor inspection equipment
Non-magnetic precision granite beams are ideal for inspection equipment equipped with magnetic-sensitive sensors, laser interferometers and high-definition imaging. Typical applications include wafer surface defect inspection tools, optical profilers, laser confocal scanning systems, glass substrate appearance inspection and photomask precision metrology. The core demand of such equipment is not heavy cutting, but stable high-precision scanning and imaging. The non-magnetic characteristic of beams protects optical paths and sensors; high dimensional stability ensures measurement data does not drift during long-time scanning; high damping suppresses vibration to guarantee clear imaging. Compared with aluminum alloy and cast iron beams, non-magnetic granite beams have no magnetization risk. Their precision decays slowly in long-term service and reduces downtime for calibration. UNPARALLELED supports customized development according to customer's chamber size, optical path layout and mounting interfaces, reserving routing slots, avoidance holes and mounting reference for optical components.
5. Full-range factory inspection to guarantee delivery quality
Besides conventional geometric precision and stiffness loading tests, finished products are inspected for magnetism to confirm that the whole beam including embedded parts is non-magnetic. Geometric precision inspection adopts CNAS traceable metrology equipment. Complete documents including cleanliness records, material test reports and loading deformation data are provided. Dust-free packaging is adopted to avoid contamination during transportation. For long-travel models, low-volatility adhesive is used for assembled beams, and joints are placed in low-stress zones without interfering with core optical and measurement reference.
Conclusion
In optical and semiconductor precision inspection equipment, stray magnetic fields directly disrupt optical imaging and weak signal measurement, which can hardly be fully avoided by traditional metal beams. UNPARALLELED non-magnetic precision granite beams adopt naturally non-magnetic stone substrates, combined with non-magnetic embedding, ultra-precision lapping and clean processing technology. They achieve non-magnetic environment, low thermal deformation, high rigidity with vibration damping and long-term dimensional stability simultaneously. Perfectly suitable for wafer inspection and optical metrology equipment, these beams provide a pure and stable motion carrier for optical systems and magnetic-sensitive measurement units.