A plurality of semiconductor chips are provided on a base substrate. The curved shaft has two curved ends and a straight portion located between the two curved ends. To maintain the focal point inside the lamella, the bubbles that result from the photodisruption are measured using a wavefront detector. If data transfer congestion is detected, the method includes marking an acknowledgement data after the marked data is received by the receiving device. Therefore, without using an additional hinge or other mechanical coupler, these two driving stems are pivotally connected with each other.