This study seeks to explain removal rate trends and scatter in thermal silicon dioxide and PECVD tetraethoxysilane-sourced silicon dioxide (PE-TEOS) CMP using an augmented version of the Langmuir-Hinshelwood mechanism. The proposed model combines the chemical and mechanical facets of interlevel dielectric (ILD) CMP and hypothesizes that the chemical reaction temperature is determined by transient flash heating. The agreement between the model and data suggests that the main source of apparent scatter in removal rate data plotted as rate versus pressure times velocity is competition between mechanical and thermochemical mechanisms. A method of visualizing removal rate data is described that shows, apart from any particular interpretative theory, that a smooth and easily interpretable surface underlies the apparent scatter.

Piezoelectric acoustic resonators are widely utilized for RF devices but most can only utilize a few different resonant frequencies on the same substrate. Contour mode resonators (CMR) have resonant frequencies defined lithographically offering the advantage of an extensive frequency range on the same film, wafer, or die. This work will discuss our efforts in developing ScAlN for CMRs to achieve RF performance suitable for use in RF filters. First we will discuss our RF sputter deposition process for creating high-performance Sc 0.12 Al 0.88 N piezoelectric films and compare it with an established sputtered piezoelectric AlN. Fabrication and integration techniques for fabricating CMRs will be then detailed. Finally, electrical design and resonator performance is then discussed. These early investigations into ScAlN films suggest that performance metrics such as k 2 eff can substantially improve while simultaneously ensuring good resonator Q factors over a wide frequency range of devices.

Removal rate results obtained from a 150 mm Speedfam-IPEC 472 polisher, coupled with a proven removal rate model has allowed for the determination of effective pressure ͑i.e., the actual pressure exerted on the structures of a patterned wafer͒ during chemical mechanical planarization ͑CMP͒ of high-density plasma-filled shallow trench isolation ͑STI͒ wafers. Results showed that the ratio of derived effective pressure to applied wafer pressure was 2.2, 1.7, and 1.3 for 10, 50, and 90% density wafers, respectively. The relative consistency of these ratios indicates that the effective pressure experienced during polishing is not impacted by pattern density in a proportionate manner.It is critical to establish a problem-free approach for shallow trench isolation ͑STI͒ chemical mechanical planarization ͑CMP͒ because STI technology presents several advantages over the previous LOCOS ͑local oxidation of silicon͒ technology such as low junction capacitance, near zero-field encroachment, and exceptional latch-up immunity. 1 The general structure and property of materials used in STI technology has caused selectivity issues ͑i.e., oxide vs. nitride removal rates͒, nitride erosion, and trench oxide dishing. The aforementioned problems are generally associated with the overall material properties ͑i.e., Young's modulus͒ of the various STI layers, as well as variations of local removal rates resulting from the effects of patterned structures on the actual wafer pressure experienced during CMP.Patterned wafers pose uniformity problems due to inconsistent planarization times resulting from variations in die-level pattern density. For a set of identical CMP process conditions and wafers with no variations in pattern density ͑i.e., uniform and repeated patterns͒, more material is removed from a wafer with a lower pattern density than from one with a higher pattern density. When considering a wafer with significant variations in pattern density, typical polishing processes yield dramatic variations in local removal rate. 2 As a result, determining local and global removal rates becomes difficult, especially when considering that little is known about the contact mechanisms at the pad-wafer interface. This limitation reduces the capability of accurately determining the actual pressure experienced by the structures on the wafer surface.This study attempts to determine the effective pressure ͑i.e., the actual pressure exerted on the structures of a patterned wafer, also known as the envelop pressure͒ during STI CMP through a series of controlled temperature STI polishes. Using removal rate results in conjunction with a simplified Langmuir-Hinshelwood kinetics mechanism for material removal, this study derives the effective pressure experienced for STI wafers ranging in pattern densities of 10-90%. 3 ExperimentalPolishing.-All polishes were completed on a Speedfam-IPEC Avanti-472 polisher using 150 mm diameter wafers. The STI wafers used in the study had pattern densities of 10, 50, and 90% and exhibited no die-level pattern density va...

In this study, we evaluate the limitations associated with variable shallow trench isolation (STI) oxide pattern densities for accurate motor current endpoint detection during chemical mechanical planarization (CMP). Results indicate that repeatable motor current endpoint detection can be achieved for STI wafers with oxide pattern density variations of up to 17.4%. Furthermore, results show that a dependence exists between the STI oxide pattern density variation and motor current endpoint success during polishing. According to the findings of this study, a suitable motor current endpoint detection system could yield successful termination points for STI polishing, as well as reduce the need for polishing reworks.

Defect centers generated in vacuum-ultraviolet irradiated chemical-mechanical polished oxides have been characterized using electron paramagnetic resonance and C-V analysis. Both oxide trap E', and interface trap PbO centers were detected in unpolished and polished oxides. In addition, another interface defect center known as the Pbl center was only identified in the polished oxides, suggesting that the polishing process altered the SiOdSi interface.