Wafer bonding is a process by which two or more mirror-polished flat surfaces are joined together. This process is increasingly used in microelectronics and microsystems industries as a key fabrication technique for various applications: production of SOI wafers, pressure sensors, accelerometers and all sorts of advanced MEMS. Unfortunately, the lack of reliability of these systems does not allow them to enter the production market. This lack of reliability is often related to the lack of understanding and control of the thermo-mechanical properties of materials used for the fabrication of MEMS (indeed, at this small scale, properties of materials are sometimes quite different than at large scale) but it is also due to the limited knowledge of the different phenomena occurring during the working of these devices, the most detrimental of them being fracture. Among all of these fracture processes, the integrity of the interfaces and, particularly, the interfaces created by wafer bonding is a generic problem with significant technological relevance. In order to understand the bonding behavior of silicon wafers, the interface chemistry occurring during the different steps of the bonding process has been detailed. The formation of strong covalent bonds across the two surfaces is responsible of the high fracture resistance of gwafer bondingh interfaces after appropriate surface treatments and annealing. The bonding process (surface treatments and annealing step) has been optimized toward reaching the best combination of interface toughness and bonding uniformity. The fracture resistance of gwafer bondingh interfaces or interface toughness has been determined using a steady-state method developed in the framework of this thesis. The high sensitivity to geometrical and environmental factors of gwafer bondingh interfaces has been quantified and related to the interface chemistry. A new technique involving the insertion of a dissipative ductile interlayer between the silicon substrate and the top silicon oxide has been proposed in order to increase the overall fracture resistance. A multiscale modeling strategy which involves the description of the interface fracture at the atomic scale, of the plasticity in the thin interlayer at the microscopic scale, and of the macroscopic structure of specimen has been used to guide the optimization of this technique. Numerical simulations have shown the influence of the ductile interlayer parameters (yield strength, workhardening exponent and thickness) and the critical strength of the interface on the overall toughness of such assemblies. A first set of experimental data has allowed increasing the interface toughness by 70%. The critical strength of the interface is finally determined by inverse identification and turns out to be in the expected range of theoretical strength. The knowledge of the strength and the fracture toughness of gwafer bondingh interfaces is of practical importance because these two values can be used in a simple fracture model (e.g. cohesive-zone model) in order to observe the behavior of such interfaces under complex loading using finite element simulations.

After Taiwan and China joined WTO and the world industry globalization trend, the competition is intense that enterprise management and worldwide allocation between Pure-Play and IDM wafer foundry. And in Mainland China, they promoted and developed IT industrial very active, specially in wafer foundry industry. By Michael E. Porter¡¦s Diamond Theory, 1. Production ; 2. Demand ; 3. Relevant and Support industry ; 4. Strategy, Structure and Competitor of Enterprises. Meanwhile, it is important of government policy, culture and leadership glamour. If we can well manage these influence factors, the country will be increased their national competition advantage. So, these are government's important duty. In this thesis, there is one synthetical comparison with five factors, such as Technical Capability, Manufacturing Managemet, Financial Advantage, Cost Controlling and Marketing. We try to study the Strategy of Positioning, Cluster Effect and Competition Advantage for wafer foundry industry of Taiwan. In Taiwan, Taiwan Semiconductor Manufacturing Corporation (TSMC) and United Microelectronics Corporation (UMC), they are world-leading semiconductor foundry companies. There is one competitor --- IBM with technology and price and another potential competitor --- SMIC with low price and capacity of mass-production

ABSTRACT The polishing stocks used in various ultra-precision polishing machines consist of abrasives, polishing disk (pad), and polishing fluids. They are expendable goods. To ensure the machining ability and the repeat accuracy of machining characteristics, the polishing disc (pad) must use the dressing mechanism to produce sharp new grains. As a result, the grinding surface on the abrasive wheel becomes thinner gradually, then losses it¡¦s machining ability, and finally must be changed. Hence, in this project, an idea of an ultra-precision abrasive machining is proposed by using the continuous composite electroplating on the polishing disc. In this idea, the machining ability of Cu polishing disc can be ensured due to the use of the continuous Sn-Al2O3 composite electroplating. Hence, it can save the cost of the ultra-precision machining using in the semiconductor wafer. In this study, after 60 minutes continuous composite electroplated polishing, the thickness of the composite coating on the surface of Cu polishing disc can increase 6.13£gm. It means the surface of disc can be grew and renewed at every moment. The removal amount of the wafer is 10.8£gm. The surface of wafer was Ra=0.5453£gm and Rmax=5.464£gm at the start ,but came to Ra=0.0019£gm and Planess=2.649£gm/36mm after 60 minutes polishing.

In conventional abrasive machining , it must using dresser to dress the surface of polishing disc periodically , in order for polishing disc to maintain its ability of machining , and then ensuring the quality of work piece. It will make polishing disk thin , finally it must losing it ability of machining , and then be replaced by a new disc. For this reason , in the study , an idea of a new type ultraprecision polisher is proposed . Using Sn-Al2O3 composite coating to reach the mirror surface grinding of silicon wafer in the tin bath , and grinding with electroplating continuously . It will ensure the ability of machining of polishing disc . In the study , first , analyzing the effect of rotational speed rate of wafer and polishing disc on the grinding trajectories type of machining surface . From the result of analysis , find that , when the rotational speed rate is more irregular or it could not divided , the arrangement of grinding trajectories is more complex . And then , investigating the effect of cathode current density , rotational speed of polishing disc and time of plating on the characteristics of composite coating . In the experiment of composite electroplating , when cathode current density is higher , the size of crystal is smaller , the thickness of coating is thicker , and the quantity of Al2O3 within coating decrease lightly . The increase of the rotational speed of polishing disk could increase the size of crystal , the thickness of coating and the quantity of Al2O3 lightly . The time of plating is longer , the shape of crystal is more obvious , the thickness of coating is thicker and it also increase the quantity of Al2O3 . Finally , investigating the effect of cathode current density and cationic surfactant PEI on the characteristics of coating and wafer . In practical abrasive machining , the removal rate of wafer increases with cathode current density , and the addition of PEI could increase the quantity of Al2O3 indeed . Besides , under the same machining condition , in the tin bath with PEI , the removal rate is higher than the one in the tin bath without PEI .

In this thesis, the residual stress distribution of metal film sputtered on silicon substrate are studied. The commercial Marc finite element method package is used in this work. The thermal-mechanical model is employed in the residual and thermal stress analysis of thin film during the sputtering process. Two models finite element are used in this study. One is the 2D axial-symmetric model and the other is the 3D. The 2D axial-symmetric model was employed to investigation the residual stress distribution in 4¡¨, 6¡¦¡¦, and 8¡¦¡¦ wafer during the UBM sputtering process. The 3D model was used to study the effects of sputtering parameters, i.e. sputtering temperature and film thickness, on the residual stress distribution. The effect of etching process on the sputtered film has also been studied by using the 3D model. Results indicate the proposed model can simulate the residual stress distribution successfully.

Zugl.: Dresden, Techn. Univ., Diss., 2009 / Hergestellt on demand

Semiconductor wafer manufacturing facilities (fab) must maintain extremely clean air environments to minimize the number of wafers scrapped due to contamination which would result in reduced yields. The fab air is cleaned bypassing it through either HEPA or ULPA filters. A number of airborne fab contaminants may be hygroscopic causing them to exist as a solid or a liquid when in equilibrium with their environment's relative humidity. The effect of relative humidity on such contaminants is poorly documented whether they were to be captured in a filter or deposited on a wafer. The work presented here experimentally characterizes NaCl evolution within HEPA filters when exposed to humidity fluctuations and the effect of humidity on NH4Cl corrosiveness when deposited on cobalt coated wafers with a TiN layer. Successive deliquescence and efflorescence fluctuations were imposed on particles captured on a glass fiber HEPA filter. Scanning Electron Microscopy (SEM) and Environmental SEM (ESEM) studies of the filters showed that the NaCl, under humidity excursions, did not penetrate deep into the filter but deliquesced and effloresced near the top surface of the filter. Pressure drop measurements for filters containing NaCl particles showed differences in pressure drop associated with relative humidity changes. These pressure drop changes suggested some redistribution particle properties. When exposed to a relative humidity of 20%, the NH4Cl particles did not corrode the cobalt wafer beyond the location of the initial deposit. At 61% relative humidity, the surrounding areas of the particles were corroded with a solid artifact left at the original location. At 76% relative humidity the NH4Cl particles were observed to have deliquesced, which is below the expected deliquescence relative humidity. The corrosion of the cobalt wafer was most extensive when the NH4Cl particles had deliquesced. / text

This dissertation presents a series of studies relating to pad-wafer and brush-wafer contact characterization in planarization and post-planarization processes. These are also evaluated with the purposes of minimizing environmental impact and reducting cost of ownership.Firstly, a new method using spectral analysis based on real-time raw friction data is developed to quantify the total amount of mechanical interaction in the brush-fluid-wafer interface in terms of stick-slip phenomena in post-planarization scrubbing. This new method is remarkable from the standpoint of its potential to eliminate having to perform a multitude of experiments needed for constructing and interpreting Stribeck curves, and its application to processes where Stribeck curves fail to yield any useful data. Moreover, this method is applied to investigate the effect of brush roller design on scrubbing process and to analyze behaviors of eccentric brushes.In order to study pad-wafer contact in planarization processes, a mechanical characterization method (incremental loading test) is developed and applied to analyze different types of pads and pad surfaces subjected to various treatments. Along with optical interferometry and theoretical analysis, flow resistance due to pad land area topography can be estimated.The greatest contribution of this dissertation involves development of real pad-wafer contact area measurement technique using confocal microscopy. The real pad-wafer contact area is a difficult property to measure in planarization, yet it is a key feature to further understand the process. A custom-made sample holder with a sapphire window and a miniature load cell is used to collect confocal images at controlled values of down force.At last, the two newly developed techniques (incremental loading test and real pad-wafer contact area measurement using confocal microscopy) together with dual emission UV enhanced fluorescence imaging are utilized to investigate conditioning effects in planarization process.

A major challenge in the manufacturing of micro and nano devices is the cleaning, rinsing, and drying of very small structures. Without a technology for in situ and real-time monitoring and controlling, the rinse processes that account for a significant fraction of the total processing steps use a large amount of water and energy perhaps unnecessarily. This "blind" processing approach leads to waste that can have significant economic and environmental impacts. An electrochemical residue sensor (ECRS) has been developed and is aimed at in situ and real-time measurement of residual contamination inside the micro and nano structures. Using this technology, the mechanisms and bottlenecks of cleaning, rinsing, and drying can be investigated and the processes can be monitored and controlled.An equivalent circuit model was developed to assist the design of the sensor; its validity was proved by the first prototype. The simulation results and the experimental data predicted a good sensitivity in a wide range of operational frequency. To use the sensor in a practical rinse tank setup, the sensor-on-wafer prototype was designed and fabricated. Both the fab-scale and the lab-scale tests were performed and results illustrated many successes. The sensor is the first and the only available technology that provides the in situ and real-time cleanness information in the microstructures during the rinse processes. The sensor results distinguished four different types of rinse processes and showed high sensitivity to the ionic concentration change in the microstructures. The impacts of cleaning and rinsing parameters such as flow rate, temperature, cleaning solution concentrations, and process time on the sulfuric acid rinsing efficiency were investigated by using the sensor. The investigation discovered that sulfuric acid rinsing is a two-stage process: a flow-control stage and a desorption-control stage. A comprehensive rinse model was developed to correlate the transport process and the trench impedance that is the sensor's signal. This model combined with the experimental data proved that increasing flow rate in the overflow rinse has a low efficiency for the rinse processes controlled by the surface reactions. The model, for the first time, shows the dynamics of the charging of the silicon dioxide surface and the dynamics of the potential build-up in the solution. It also discovered that the cation rinsing is a challenge if the cation adsorbs on or reacts with the surface.

No description available.