Through-Silicon via Submount for Flip-Chip LEDs

Abstract

A blue light emitting diode (LED) was prepared by a flip-chip (FC) LED and three-dimensional through-silicon via (3D-TSV) technique. The experimental results indicated that the diameter and length of the Si via were about 180 μm and 400 μm, respectively. The Cu was uniformly and high density filled in each TSV, and the average resistance was about 0.14 m . It was also found that the 96.43Sn-3.57at%Ag bumps were electroplated on the Cu plugged TSVs of a silicon substrate, and these were smoother at 250 • C. After reflow, a 3D blue light emitting diode was prepared by peak bonding at 250 The increasing use of light emitting diodes (LED) in products has promoted the development of higher power, greater density, and lower cost devices. Compared with conventional LED, flip-chip (FC) LED 1-3 have a number of advantages, such as about twice the light output of conventional LED. Flip-chip technology not only shortens the production process, but also significantly reduces thermal resistance and results in a greater heat dissipation rate than seen with the traditional gold wire bonded LED. Moreover, the direct contact of the electrodes or bumps with the package structure can substantially enhance the cooling effect. The flip-chip approach can also remove wire bonding and other wire frame processes, and so these LED can be used with high current drivers.4,5 Therefore, FC LED are attracting growing interest due to their greater heat dissipation, better light emission, higher reliability, and more efficient bonding processes than seen with traditional wire bonded LED.The typical bonding process recommended by chip companies for FC LED is Au/Sn eutectic bonding.6 However, eutectic Sn-Ag alloy is a promising candidate among the various Pb-free solder materials for use with FC LED, and the resulting Sn-Ag alloy bumps 7 can be easily obtained by annealing the Ag/Sn metal stack.There is also demand for new packaging processes for FC LED. 8The use of three-dimensional (3D) packaging through-silicon via (TSV) technology allows a high density of vertical interconnects, unlike 2D packing, as shown in Figure 1. 3D TSV ICs have the following advantages: (1) reduced connection lengths, and thus smaller parasitic capacitance, inductance, and resistance; (2) high-speed low-power interconnects; and (3) a combination of monolithic and multifunctional integration. In this study, a blue LED was prepared using an FC LED and the 3D-TSV technique. We thus propose a new method to achieve 3D LED packing. The detailed fabrication of the TSV and the electrooptical properties of the fabricated are also discussed. ExperimentalFigure 2 presents a schematic diagram of the fabrication process for the 3D LED. A P-type 400 μm thick Si wafer was used as the bottom substrate. Photolithography was used to make a mask for etching the Al layer. A positive type photoresist, AZ-1500, was spin-coated to a thickness of 2 μm with a rotation speed of 500 rpm for 15 s, followed by 3000 rpm for 30 s. The Al layer was etched by wet etching, after using acetone to remove...

3D RGB Light Emitting Diodes Prepared by Through Silicon Via Technology

“…The authors recently reported the fabrication of a 3D LED structure. 5 In this study, the TSV and LED chips are smaller. A 6-inch P-type 350 μm thick Si wafer was wet cleaned in a standard RCA process and used as a lower substrate.…”

“…The respective values for the parameters for the TSV process for the flow of SF 6 gas and O 2 gas, the substrate temperature, z E-mail: tj.hsueh@gmail.com the etching time, the electrode gap, the RF power and the pressure in the chamber were 60 sccm, 5.4 sccm, −117 • C, 150 min, 7 cm, 1000 W and 10 mTorr. 5 Then the barrier layer Al was removed by aluminum etching. An isolation layer SiO 2 with a thickness of 800nm was formed by thermal oxidation.…”

A Room-Temperature TiO2-based Ammonia Gas Sensor with Three-Dimensional Through-Silicon-Via Structure

“…28 Moore's law is the subject of many studies, which use a throughsilicon via (TSV) technology to fabricate a three-dimensional (3D) integrated circuit (IC). TSV technology is used in electric devices and LED's, 29,30 humidity sensors, 31 photo sensors 32 and field emission. 33 This study produces a 3D room temperature TiO 2 NH 3 gas sensor using TSV technology and atomic layer deposition (ALD).…”

Via-Hole-Type Flip-Chip Packaging to Improve the Thermal Characteristics and Reliability of Blue Light Emitting Diodes

“…[7][8][9][10][11][12] It is found that the use of FCLEDs is more advantageous than lateral LEDs in achieving high luminous intensity and efficient heat dissipation because photons are extracted through the transparent sapphire substrate and the use of bonding wire is obviated,. [10][11][12][13][14][15] In particular, the removal of wire bonding can increase electrical contact area and reduce current crowding, resulting in a lower forward bias voltage. Furthermore, the deterioration of ray-uniformity caused by the bonding wire can be alleviated.…”

“…Since the disconnection of bonding wire can result in device failure, the elimination of the wire can eventually improve the reliability of devices. [10][11][12][13][14][15] In FCLED packaging, the thermal resistance of the packaged devices is directly affected by die bonding. Particularly, voids are known to readily form in the solder layers during the manufacturing process [16][17][18] and grow larger as a result of thermal cycles and thermal stress.…”