In the precision laboratory for manufacturing chips, there is a seemingly unremarkable "behind-the-scenes hero" - the granite machine base. Don't underestimate this stone. It is the key to ensuring the accuracy of non-destructive testing of wafers! Today, let's take a look at how it keeps the detection equipment always "horizontal and vertical".
1. Born with a "stable gene"
Granite is no ordinary stone. Its internal structure is like a tightly interlocked "mineral jigsaw puzzle". Quartz, feldspar and other crystals are closely arranged, with extremely high density and almost no voids. This is just like building a house with reinforced concrete, which is both solid and stable. When the inspection equipment "sits" on it, even if it weighs several tons, the deformation of the granite base is negligible, only one-tenth of that of steel!
Even more impressive is that it is almost not afraid of temperature changes. Ordinary metal materials tend to "expand and gain weight" when heated and "contract and become thinner" when cooled. However, granite seems to have a "constant temperature magic". When the temperature fluctuates by 1℃, its expansion and contraction is only one-thousandth of that of a human hair. It should be noted that even if there is a slight change in the temperature of the testing laboratory, the granite base can firmly support the equipment and prevent the levelness from "deviating".
Second, the processing technique of "devilish details"
To make the granite base more accurate, engineers employed "black technology" for processing. Imagine polishing stones with "super sandpaper" made of diamonds - this is how a five-axis grinding machine works. It will grind the surface of the granite to be flatter than a mirror in three steps:
Rough grinding: First, remove the surface blemishes of the stone and control the flatness to one-twentieth of a human hair.
Semi-fine grinding: Further refinement, with the flatness increased to one-fiftieth of a human hair.
Fine grinding: Finally, it is polished with ultra-fine grinding powder, achieving a flatness of one-thousandth of a human hair! At this point, the surface of the granite base is like a "horizontal stage" tailor-made for the inspection equipment.
Some high-end mounts also have a "smart brain" - the built-in high-precision level is like a "little guard" on duty 24 hours a day. Once it detects that the equipment is tilted by 0.01 degrees (an Angle smaller than that of a pen tip), the hydraulic device will immediately activate and "straighten" the equipment within 30 seconds.
Third, ingenious design further enhances stability
The engineers also racked their brains on the structure of the machine base. The bottom is made into a hexagonal honeycomb shape, just like a bee's hive, which not only reduces the weight but also evenly distributes the pressure. When the detection probe moves on the wafer, the deformation at each point of the base is almost exactly the same, ensuring that the horizontal reference remains stable all the time.
Even more amazing is that an "invisible shock absorber" - a piezoelectric ceramic shock absorber - is installed between the base and the ground. It can capture various vibrations ranging from 1 to 1000Hz like a radar and immediately emit reverse waves to "counteract" the interference. For instance, the vibrations generated by the operation of the machines next door or the jolts of vehicles passing by outside are all "useless" in front of it.
Data speaks for itself: How Powerful Is the effect?
In practical applications, the performance of the granite base is truly astonishing:
Optical inspection: The accuracy of identifying surface defects on wafers has been improved from 3 microns to 1 micron (1 micron = one-sixtieth of a human hair).
Ultrasonic testing: The error in measuring wafer thickness has been reduced by three quarters.
Long-term use: After continuous operation for a year, the change in levelness is almost negligible, while ordinary machine bases have long become "hunched over".
From the advantages of natural materials to precise processing and innovative design, the granite base has proved with its "strength" that if you want to accurately detect chips, this stone is really indispensable!
Post time: Jun-18-2025