Alternative approach in 3D MEMS-IC integration using fluidic self-assembly techniques

Abstract

Nowadays, industries are investigating new, original and appropriate solutions to address challenges in 3D MEMS-IC large-scale integration. Self-assembly techniques are among those. We report on an alternative approach inspired from fluidic self-assembly and using the flip-chip method. Here, solder bumps are directly formed onto a MEMS chip using liquid solder solution in a bath. The self-alignment process is operated after surface treatment by plasma deposition to form high and low wettability selective patterns. Finally, MEMS and electronic chips are permanently bonded after low thermal heating without any pressure. Electrical contact is established and electromechanisms of the microsystems are proven. Compared to classic MEMS-IC flip-chip methods, this strategy presents many advantages: it is a low-cost and fast fabrication process requiring no specific equipment for deposition of solder bumps. Furthermore, it can be applied on different substrates and it does not require a specific pressure method during the bonding process. This strategy is also an appropriate fabrication method for large-scale MEMS integration where electronic connection density is high.

Re-engineering artificial muscle with microhydraulics

“…Although we used classical microfabrication techniques, MSAs lend themselves to roll-to-roll processing and imprint lithography. Assembly of the actuator fluids and the setting of droplet pressures requires some degree of self-assembly 26 and still needs more development, as do techniques to assemble MSAs into appropriate 3D configurations.…”

High-Efficient Chip to Wafer Self-Alignment and Bonding Applicable to MEMS-IC Flexible Integration

“…Compared to other surface treatment materials or process for self-alignment, e.g. metal, Au with SAM, dry etching [16], [17], or lift-off processed SiO 2 /Al pattern [18], our proposed FDTS pattern method offers unique and attractive advantageous of simple process, low-cost, which is applicable to MEMS-IC flexible integration.…”

Surface-tension driven self-assembly of microchips on hydrophobic receptor sites with water using forced wetting

“…Surface-tension driven self-assembly and hybridassembly of microchips is a topic attracted wide interests. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] One key aspect of the technology is a well-designed receptor site where the self-alignment process of the selfassembly will take place. The general rule is that the receptor site should be lyophilic (against the lyophobic background) to the self-alignment medium-the liquid medium between the receptor site and the micropart to be assembled, e.g., hydrophilic receptor site if water is used as the self-alignment medium in air [6][7][8][9][10][11] or oleophilic receptor site if adhesive is used as self-alignment medium in water.…”

“…The general rule is that the receptor site should be lyophilic (against the lyophobic background) to the self-alignment medium-the liquid medium between the receptor site and the micropart to be assembled, e.g., hydrophilic receptor site if water is used as the self-alignment medium in air [6][7][8][9][10][11] or oleophilic receptor site if adhesive is used as self-alignment medium in water. [1][2][3][4][5] In air, solid-edges can also be used as the boundary for the self-alignment process. 12,15 However, the general rule of a lyophilic receptor site still applies.…”