Surface Tension-Driven Self-Alignment of Microchips on Low-Precision Receptors

Surface tension-driven self-alignment is reported to be very accurate when the chip and receptor site are well-defined. This paper investigates surface tension-driven self-alignment of microchips on low-precision receptors through experimental studies and theoretical analysis to understand the relation between alignment accuracy and the precision of the receptor edges. Three different types of low-precision receptors have been designed and fabricated to study the alignment accuracy: 1) receptors with a single triangular defect pointing outward or inward with amplitude of 10, 30, and 60 μm and corresponding width of 20, 60, and 120 μm; 2) receptors with constant triangular edge jaggedness with amplitude of 2, 4, 5, and 15 μm; and 3) receptors with random triangular edge jaggedness with amplitude of 2, 4, and 8 μm. The DI water is used as the self-alignment medium. The alignment accuracy has been closely measured with an environmental scanning electron microscope. Numerical simulators, e.g., surface evolver have been used to analyze the results. The experimental results show that low-precision receptors impair alignment accuracy in a much lesser degree than the scale of the defects on a receptor.