Papers by Keyword: CMP

Abstract: At present there are many challenges in the acidity slurry used widely. And the toxic BTA with side effect must be used in the international. So the component of slurry must be improved. The new reagent is studied. It makes the slurry alkalization. It also has the using as a pH adjusting agent, complexion agent of copper ion, multi- metal chelating agents, aminating agent of acidic oxides, pH buffer, stainless steel corrosion inhibitor, the active agent and pro-oxidant. It improves the property of slurry and solves many different of acidity slurry. The alkalinity slurry contained the multi-hydroxyl polyamines is environmental、inexpensive and composition- simplified. The slurry with it can achieve the high speed and high flat. In the same time the low pressure and the little abrasive can be realized, which provide the new material for the removal of copper film.

Abstract: In the process of very large scale integrated circuit (VLSI) manufacturing, Chemical Mechanical Polishing (CMP) technique is one of the most effective wafer global planarization techniques. The polishing quality depends not only on the slurry and polishing head structure, but also on accurately wafer polishing pressure control. However, the polishing pressure accurately control depends on a generalized pressure control system of the polishing head and multi-zones pneumatic pressure system. As the system has time-varying, nonlinear and coupling characters, it is difficult to apply theoretical modeling method for obtaining the accurate mathematical model. Therefore, this paper presents a method based on subsubmodel identification to establish the precise mathematical model of the pressure control system. The experimental results show that the method is feasible, practical and accurate.

Abstract: In order to achieve high removal rate and high-quality processing on SiC wafer, we carried out the CMP processing experiment with the new type CMP machine (Bell-jar) by using the slurry with the addition of strong oxidant (KMnO₄). It was found that the high speed CMP processing was achieved by controlling the concentration of KMnO₄ in the slurry, the pH of slurry and the processing atmosphere. By using the slurry with the addition of KMnO₄ of 0.1mol/L, the removal rate was the fastest up to 1019nm/h in the fixed pH of 6. By use of the slurry of pH 3, the removal rate of C-face of SiC wafer was 1695nm/h On the other hand, the fastest removal rate of Si-face of SiC wafer was only 51nm/h by using the slurry whose pH is 7. In the open air atmosphere, the removal rate was 915nm/h, which was higher than that at the higher and lower atmospheric pressure.

Abstract: We have developed a chemical process for atomic planarization of gallium nitride (GaN) using a platinum catalyst and ultraviolet (UV) light irradiation. The process is mediated by a hydrolysis reaction catalyzed by platinum as a solid catalyst. Because the reaction occurs selectively from the step edges, a flat surface composed of a straight step-and-terrace structure is obtained. In the absence of UV light, owing to the low step edge density, the removal rate is quite slow, approximately 1 nm/h. In contrast, under UV light, etch pits are formed on the terraces by photo-electrochemical etching causing an increase in the step edge density. We achieved surface planarization with a removal rate of 9.6 nm/h assisted by irradiation with UV light.

Abstract: In this work, we developed a computational fluid dynamics (CFD) model to simulate the slurry flow between the wafers and pad during the chemical mechanical polishing (CMP) process under a multiple-wafer configuration. A serial of simulations were carried out to visualise slurry flow and explore the effects of the process variables concerned on the flow velocity and pressure distributions beneath the wafers. Through the model and simulation, the flow field characteristics were obtained and analyzed under different operating conditions. The results can provide an insight into a fundamental understanding of the slurry flow behaviours under the multiple-wafer configuration and some useful implications for the selection of practical polishing variables.

Abstract: Influences of wafer-related defect and gate oxide fabrication process on MOS characteristics with gate oxides thermally grown on 4H-SiC (0001) wafer have been investigated for a realization of SiC MOS power devices. The SiC MOS characteristics depend on the gate oxide fabrication process, and are improved by the increase of DRY oxidation temperature and the applying of N2O and H2 POAs. In addition, it was clearly shown that predominant origins of SiC MOS reliability degradation are wafer-related defects such as dislocation and surface defects of epitaxial layer. Moreover, the planarization of SiC epitaxial layer surface using a CMP treatment is effective technique for the improvement of SiC MOS reliability.

Abstract: In this work, we made an off-axis surface of SiC with Mechano-chemical polishing method to examine the influence that an atomic step gave for electronic properties of devices. Low energy ion scattering spectroscopy was shown Si-face and C-face with SiC structure were polished with monocrystal. We consider that there results above the atomic step on the surface influence to a device properties, especially a leakage current of Schottky diode. C atom at the step and terrace cause leakage event at metal-semiconductor interface of Schottky diode have been clarified by conductive atomic force microscopy.

Abstract: The “Memory Wall” problem has become a bottleneck for the performance of processor, and on-chip multiprocessor(CMP) aggravates the memory access latency. So many hardware prefetching techniques have been brought to solve this challenge, i.e. Future Execution. This paper introduces runahead execution(another hardware prefetching technique firstly used on single-core processor) and Future Execution, then it brings up some improvement for Future Execution and gives the result and analysis of data tested by SPEC2000 benchmark.

Abstract: The technology of ultrasonic assisted machining has been successfully used in many machining processes recently. Conditioning in the CMP not only can extending the life of the polishing pad but also improve process stability. In this paper we develop a brand new conditioning process with ultrasonic assisted conditioning UAC head for chemical mechanical polishing CMP process. The slurry came from inside the polishing spindle and had an independent cyclic system. As a result, this UAC device can remove polishing debris 4-6 times faster than conventional conditioning process. This conditioning process may even use water instead of slurry to reduce the cost of consumables of CMP. Key word: Chemical mechanical polishing CMP, Ultrasonic assisted conditioning UAC, Polishing Pad

Abstract: In a chemical mechanical polishing (CMP) process, the removal rate is affected by the actual contact conditions between the wafer and the polishing pad. The polishing pad is one of the most important consumable materials: when the wafer is polished, the pad surface asperity changes. Further, the polishing pad surface asperity has a substantial influence on the actual contact conditions. Therefore, measurement and quantitative evaluation methods for the pad surface asperity have been proposed by various research institutes. We have developed a novel measurement and quantitative evaluation method for polishing pad surface asperity based on contact image analysis using an image rotation prism. We have proposed four effective evaluation parameters: the number of contact points, the contact ratio, the maximum value of the minimum spacing of the contact points, and the half-width of the peak of the spatial Fast Fourier transform (FFT) result of a contact image. This paper discusses the change in the polishing pad surface asperity measured by the proposed evaluation parameters in serial batch polishing tests. In particular, this research focused on the relationships between the proposed evaluation parameters and the removal rate, which change with an increase in the number of serial batch polishing tests. As a result, linear correlations were found between the evaluation parameters and the removal rate.