In the semiconductor industry, conventional electronic device structures are
inadequate to satisfy the steadily growing demands for higher performances.
The development of electronic devices is moving toward higher speed,
more integrated functions and compact volume. Low and ultra-low package
height in the case of chips cards, miniaturized size with increased density
of integrated circuits, the requirement for enhanced electrical performance
of power semiconductors and high frequency devices are driving the
development of thin wafer technology. Thin silicon wafer offers a variety of
new possibilities in micro-electronic, solar and micromechanical industries,
e.g. for three-dimensional integration of stacked dies, thin micro-electro
mechanical packages or thin single crystalline solar cells. Furthermore, the
mechanical flexibility of thin wafers is ideal for bendable systems, such as
smart cards, chip-in-paper and contactless labels. By reducing the thickness
of silicon substrate, the device is moved closer to the metal heat sink so that
it conducts away from the active area more effectively, which is critical for
high-frequency operation. Today, silicon wafer thickness is getting thinner,
down to 50 microns or less.1,2 Therefore, micromachining of silicon wafer
has been one of the crucial issues in miniaturized device manufacture.