Optimized Process and Tool Design for GaN Chemical Mechanical Planarization

Abstract Many semiconductor products are manufactured with mature technologies involving the uses of aluminum (Al) lines and tungsten (W) vias. High resistances of the vias were sometimes observed only after electrical or thermal stress. A layer of Ti oxide was found on such a via. In the wafer processing, the post W chemical mechanical planarization (WCMP) cleaning left residual W oxide on the W plugs. Ti from the overlaying metal line spontaneously reduced the W oxide, through which Ti oxide formed. Compared with W oxide, the Ti oxide has a larger formation enthalpy, and the valence electrons of Ti are more tightly bound to the O ion cores. As a result, the Ti oxide is more resistive than the W oxide. Consequently, the die functioned well in the first test in the fab, but the via resistance increased significantly after a thermal stress, which led to device failure in the second test. The NH4OH concentration was therefore increased to more effectively remove residual W oxide, which solved the problem. The thermal stress had prevented the latent issue from becoming a more costly field failure.

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A Proof for the Possibility of Ce-Oxide from CMP Residuals in Si-Wafers by Analytical TEM

ISTFA 2012: Conference Proceedings from the 38th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2012p0347 ◽

2012 ◽

Author(s):

Wayne Zhao ◽

Liem Do Thanh ◽

Michael Gribelyuk ◽

Mary-Ann Zaitz ◽

Wing Lai

Keyword(s):

Technology Development ◽

Early Stage ◽

Chemical Mechanical Planarization ◽

Particle Cluster ◽

Limited Region ◽

Physical Evidence ◽

Analytical Tem ◽

Transmission Electron ◽

Oxide Particles

Abstract Inclusion of cerium (Ce) oxide particles as an abrasive into chemical mechanical planarization (CMP) slurries has become popular for wafer fabs below the 45nm technology node due to better polishing quality and improved CMP selectivity. Transmission electron microscopy (TEM) has difficulties finding and identifying Ce-oxide residuals due to the limited region of analysis unless dedicated efforts to search for them are employed. This article presents a case study that proved the concept in which physical evidence of Ce-rich particles was directly identified by analytical TEM during a CMP tool qualification in the early stage of 20nm node technology development. This justifies the need to setup in-fab monitoring for trace amounts of CMP residuals in Si-based wafer foundries. The fact that Cr resided right above the Ce-O particle cluster, further proved that the Ce-O particles were from the wafer and not introduced during the sample preparation.

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A Resonant Pressure Microsensor with a Wide Pressure Measurement Range

Micromachines ◽

10.3390/mi12040382 ◽

2021 ◽

Vol 12 (4) ◽

pp. 382

Author(s):

Chao Xiang ◽

Yulan Lu ◽

Chao Cheng ◽

Junbo Wang ◽

Deyong Chen ◽

...

Keyword(s):

Chemical Mechanical Planarization ◽

Measurement Range ◽

Silicon On Insulator ◽

Anodic Bonding ◽

Pressure Measurements ◽

Quality Factors ◽

Deep Reactive Ion Etching ◽

Wide Range ◽

Form Pressure ◽

Silicon Islands

This paper presents a resonant pressure microsensor with a wide range of pressure measurements. The developed microsensor is mainly composed of a silicon-on-insulator (SOI) wafer to form pressure-sensing elements, and a silicon-on-glass (SOG) cap to form vacuum encapsulation. To realize a wide range of pressure measurements, silicon islands were deployed on the device layer of the SOI wafer to enhance equivalent stiffness and structural stability of the pressure-sensitive diaphragm. Moreover, a cylindrical vacuum cavity was deployed on the SOG cap with the purpose to decrease the stresses generated during the silicon-to-glass contact during pressure measurements. The fabrication processes mainly contained photolithography, deep reactive ion etching (DRIE), chemical mechanical planarization (CMP) and anodic bonding. According to the characterization experiments, the quality factors of the resonators were higher than 15,000 with pressure sensitivities of 0.51 Hz/kPa (resonator I), −1.75 Hz/kPa (resonator II) and temperature coefficients of frequency of 1.92 Hz/°C (resonator I), 1.98 Hz/°C (resonator II). Following temperature compensation, the fitting error of the microsensor was within the range of 0.006% FS and the measurement accuracy was as high as 0.017% FS in the pressure range of 200 ~ 7000 kPa and the temperature range of −40 °C to 80 °C.

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Development of an Intelligent CAD System for Involute Cylindrical Gear Cutting Tools

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.532.249 ◽

2014 ◽

Vol 532 ◽

pp. 249-252

Author(s):

Ying Hua Liao ◽

Gao Jun Liu ◽

Xiang Guo Sun

Keyword(s):

Expert Knowledge ◽

Cutting Tools ◽

3D Models ◽

Tool Design ◽

Cylindrical Gear ◽

Intelligent Cad ◽

Forward Reasoning ◽

Cad System ◽

Gear Cutting ◽

2D And 3D

An intelligent CAD system for Involute cylindrical gear cutting tools is developed by VC++ and SQL server, and it includes four modules, such as user interface, instance query, intelligent gear tool design and database. The intelligent gear tool design is the key to the intelligent CAD system, and it is based on the forward reasoning production system, and as the Intelligent reasoning technology is used for gear tool design, a lots of expert knowledge could be made full use of. The design results by the developed intelligent CAD system are more reasonable than those by a traditional CAD system, and the efficiency and quality of the gear tool design also could be improved. The developed intelligent CAD system supports both 2D and 3D models, which can lay foundation for CAD/CAE/CAM integration of gear cutting tools.

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Novel Abrasive-Impregnated Pads and Diamond Plates for the Grinding and Lapping of Single-Crystal Silicon Carbide Wafers

Applied Sciences ◽

10.3390/app11041783 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1783

Author(s):

Ming-Yi Tsai ◽

Kun-Ying Li ◽

Sun-Yu Ji

Keyword(s):

Silicon Carbide ◽

Wear Rate ◽

Single Crystal ◽

Traditional Method ◽

Removal Rate ◽

Chemical Mechanical Planarization ◽

Single Crystal Silicon ◽

Crystal Silicon ◽

Diamond Grit ◽

Ceramic Binder

In this study, special ceramic grinding plates impregnated with diamond grit and other abrasives, as well as self-made lapping plates, were used to prepare the surface of single-crystal silicon carbide (SiC) wafers. This novel approach enhanced the process and reduced the final chemical mechanical planarization (CMP) polishing time. Two different grinding plates with pads impregnated with mixed abrasives were prepared: one with self-modified diamond + SiC and a ceramic binder and one with self-modified diamond + SiO2 + Al2O3 + SiC and a ceramic binder. The surface properties and removal rate of the SiC substrate were investigated and a comparison with the traditional method was conducted. The experimental results showed that the material removal rate (MRR) was higher for the SiC substrate with the mixed abrasive lapping plate than for the traditional method. The grinding wear rate could be reduced by 31.6%. The surface roughness of the samples polished using the diamond-impregnated lapping plate was markedly better than that of the samples polished using the copper plate. However, while the surface finish was better and the grinding efficiency was high, the wear rate of the mixed abrasive-impregnated polishing plates was high. This was a clear indication that this novel method was effective and could be used for SiC grinding and lapping.

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