Wafer tweezers
Wafer tweezers are special tweezers (a gripping auxiliary tool) for the handling of sensitive semiconductor - wafers without excessive contact. Generally speaking, there are two different types of wafer tweezers: mechanical tweezers and vacuum tweezers.
Mechanical tweezers
The mechanical tweezers largely correspond to everyday tweezers, in which two gripping arms are moved towards each other by applying slight pressure. However, they have a particularly wide "tip" of 1 to 2 centimeters in order to grip the relatively large wafers with diameters of 5 to 30 centimeters.
Plastic (often polyester ) is generally used as the material for the smooth gripping surface . Tweezers with gripping surfaces made of harder material such as metal or ceramics and possibly with retaining grooves are less suitable for handling wafers, since they can damage wafer surfaces and the nanometer-sized structures on them. In addition, they can generate particles that should generally be avoided in semiconductor technology , since they reduce the production yield.
Vacuum tweezers
Vacuum tweezers work on the suction principle . To grasp a wafer, a flat tweezer insert is guided to the back of the wafer that is not equipped with circuits. The tweezer insert is equipped with a vacuum nozzle and the wafer is drawn towards the insert via the negative pressure generated by the vacuum suction.
As with manual tweezers, the tweezer inserts of vacuum tweezers are made of plastic, for example ESD - PEEK . The size of the inserts depends on the size of the wafer to be transported. Vacuum wafer tweezers are available both in a stationary version, in which the tweezers are connected to a laboratory vacuum, for example, and in a mobile, battery-operated variant, which is usually slightly larger than a commercially available electric toothbrush .