Manufacturing Bits: Aug. 2

CMP replacement?; nano-vise; MEMS/photonics packaging.


CMP replacement?
For years, chipmakers have used chemical-mechanical-polishing (CMP) tools to smooth or polish the surface of a wafer.

CMP works, but the technology is time-consuming and expensive. CMP can also leave unwanted residual patterns and defects near the surface.

In response, Russia’s National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) has helped developed an accelerated cluster ion technology that could supplement or replace CMP, at least for select applications.

Specifically, researchers used the technology for the planarization of silicon carbide materials. For this, they used Exogenesis’ NanoAccel technology. Exogenesis’ technology, known as an accelerated neutral atom beam (ANAB), creates a beam of accelerated gas cluster ions. It has been used to provide “angstrom-level smoothing” of starting materials with a Ra of <500nm, according to Exogenesis.

a) AFM of the surface of 6H-SiC before planarization; b) after radiation by ion-cluster beam (Source: National Research Nuclear University MEPhI)

a) AFM of the surface of 6H-SiC before planarization; b) after radiation by ion-cluster beam (Source: National Research Nuclear University MEPhI)

With this technology, researchers looked at the impact of ion-cluster radiation on the topology of 6Н-SiC crystals. Argon clusters were ionized and accelerated by the pressure of 30 KeV. The results show a smoothing of the 6H-SiC surface. The Rq parameter is lowered 1.5 to 2 times, according to researchers.

The Argonne National Laboratory and others have developed a nano-vise based on synthetic diamonds. The vise enables static pressures beyond 1 terapascals—-or ten million times the atmospheric pressure at the earth’s surface.

The ability to probe matter at high static pressures enables researchers to gain a better understanding of physics and the chemistry of materials.

In the lab, researchers synthesized microballs of nanocrystalline diamond. The nano-diamonds have a strength of ~460 GPa at a confining pressure of ~70 GPa, according to researchers. Then, the nano-diamond balls are used to devise a double-stage diamond anvil cell. In operation, the anvil cell works like a vise. It squeezes a sample at enormous static pressures.

Researchers have also devised a system, in which a high power laser can shine through the diamond anvil and nano-diamond. Then, the sample can be probed using synchrotron X-ray techniques.

A double-stage diamond anvil cell mounted at the beamline at Argonne. (Image: Vitali Prakapenka)

A double-stage diamond anvil cell mounted at the beamline at Argonne. (Image: Vitali Prakapenka)

“Achieving ultra-high pressures opens new horizons for a deeper understanding of matter,” said Leonid Dubrovinsky, a scientist at the University of Bayreuth, who was one of the developers of the new method. “It is of great importance for the fundamental sciences, for modeling the interior of giant planets and for the development of novel materials with unusual properties for technological applications.”

MEMS/photonics packaging
A*STAR’s Institute of Microelectronics (IME) has launched two consortia on advanced packaging–the Silicon Photonics Packaging consortium (Phase II) and the MEMS Wafer Level Chip Scale Packaging (WLCSP) consortium.

The two groups will develop new and low-cost solutions for the heterogeneous integration of MEMS and silicon photonics devices.

The new silicon photonics group includes Accelink Technologies, Corning, Fujikura, Fraunhofer Heinrich Hertz Institute, NTT and others.

In the previous Silicon Photonics Packaging Consortium (Phase I), IME and its partners developed a way to integrate low profile lateral fiber assembly, laser diode and photonics devices. The group demonstrated a fiber-chip-fiber loss of less than 8 decibel (dB).

The new Silicon Photonics Packaging Consortium (Phase II) will develop a silicon photonics packaging methodology. The consortium will develop silicon coupling modules, and provide a series of packaging solutions for laser diode integration.

Meanwhile, IME’s new MEMS WLCSP Consortium includes Delta Electronics, InvenSense, Standing Egg, STATS ChipPAC and Ulvac.

The group will develop an integration packaging platform for capped MEMS and CMOS devices, which could be used for any MEMS device with a cavity-capping technique. This includes timing devices, inertial sensors and RF MEMS packaging.
To enable this technology, the group hopes to develop a TSV-free, over-mold wafer level packaging solution for a MEMS-capped wafer.

“Through these collaborations, we will elevate our capabilities from developing MEMS and silicon photonics devices to developing advanced solutions in heterogeneous integration,” said Dim-Lee Kwong, executive director of IME.