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Solid freeform fabrication processes offer the manufacturing flexibility for tools with low thermal inertia and internal conformal channels for rapid thermal cycling in injection molding. This article analyzed each step of a rapid thermal cycling process and provided quantitative guidance for tooling design. The proposed design methodology was tested on a three-dimensional (3D) printed benchmark tool with truss support. Rapid cooling test on the benchmark tool resulted in the mold time constant shorter than 2.3 s and the cavity temperature uniformity better than 3 ° C. Preliminary tests demonstrated the technical feasibility of using a solid freeform fabrication process to fabricate low thermal inertia tools for improved heat management in injection molding. POLYM. ENG. SCI., 49:305-316, 2009. [C] 2008 Society of Plastics Engineers, INTRODUCTION Many thermoplastic manufacturing processes, such as molding and forming, involve repetitive cycles of heating, filling, cooling, and ejection. Rapid heating and cooling of the tool is always desirable for [...]

The Run by Run Controller provides a framework for controlling a process which is subject to disturbances such as shifts and drifts as a normal part of its operation. The Run by Run Controller combines the advantages of both Statistical Process Control (SPC) and Feedback Control. It has three components: Rapid Mode, Gradual Mode, and Generalized SPC. Rapid mode adapts to sudden shifts in the process such as those caused by maintenance operations. Gradual mode adapts to gradual drifts in the process such as those caused by build-up of deposition inside a reactor. The choice between the two modes is determined by the outcome from Generalized SPC which allows SPC to be applied to a process while it is being tuned. The Run by Run Controller has been applied to the control of a silicon epitaxy process in a barrel reactor. Rapid mode recovered the process within 3 runs after a disturbance. Gradual mode reduced the variation of the process by a factor of 2.7 as compared to historical data.

Spatial uniformity, or the uniformity of product output characteristics at different locations in a batch of product is modeled, optimized, and controlled using a methodology called 'Multiple Response Surfaces' which may be used to characterize the results of an experimental design. Multiple, low-order polynomial models are used to model the output characteristics at each of several sites within a batch of product. The uniformity model is then obtained by manipulating these multiple models. The Multiple Response Surfaces approach is compared to the traditional method of fitting a single high-order polynomial to the calculated uniformity. Experimental results on several processes, confirm the expectation that similar or improved modeling accuracy is obtained with fewer data points using the new methodology due to the ability to use low-order models. Characteristics of the Multiple Response Surfaces approach including noise immunity and restrictions to classes of model forms are examined both analytically and in application to plasma etching, silicon epitaxy, tungsten CVD and the simulation of polysilicon LPCVD.

When solidifying molten silicon in contact with a foreign substrate, the interfacial interaction between silicon and the substrate material can affect the nucleation behavior and therefore the final grain structure. This work illuminates the nucleation properties of different materials using differential scanning calorimetry to measure the undercooling below the melting temperature of molten silicon in contact with silicon oxides and nitrides. Both dry and wet thermal oxides show greater than 120 °C of undercooling before nucleation occurs, while silicon nitride consistently shows less than 17 °C. Variability in measured undercooling was minimized by improving coating uniformity but is not necessarily affected by overall sample deformation. A double-layer coating of silicon nitride over dry oxide reduced the dry oxide undercooling to <56 °C due to inter-layer thermal stresses, which can be minimized by reducing the outer layer of silicon nitride to <40 nm. The double-layer SiNx-SiO2 coating produced larger grains than the SiNx coating alone, when applied to a wafer recrystallization process. [ABSTRACT FROM AUTHOR]

This paper describes the development of a method to characterize the temperature profile of silicon wafers in high-temperature environments. Monocrystalline wafers are implanted on one surface with B and P ions, which diffuse into the wafer at different rates based on the temperature-dependent diffusivity of the ions during a 30 min soak in the high-temperature environment between 1000 and 1400 °C. The use of two different dopant species, instead of one, yields higher sensitivity of the measured resistance to changes in temperature in this high-temperature range. The ρ-T relation is simulated using TSUPREM-4 and calibrated using a furnace of known temperature. The final sheet resistance varies spatially between 50 and 250 Ω/sq, and can be related to the temperature of each part of the wafer during the soak step, with a sensitivity of ∼0.5 Ω/°C, and a two-dimensional temperature map can be extracted. The method is demonstrated on wafers by characterizing the hot zone of a high-temperature furnace. [ABSTRACT FROM AUTHOR]

XIAORONG XU [1] EMANUEL SACHS [1] SAMUEL ALLEN [2] Solid Freeform Fabrication technologies have demonstrated the potential to produce tooling with cooling channels, which are conformal to the molding cavity. [...]

EMANUEL SACHS [1] EDWARD WYLONIS [1] SAMUEL ALLEN [2] MICHAEL CIMA [2] HONGLIN GUO [2] A Solid Freeform Fabrication Process called Three Dimensional Printing is applied to the fabrication of [...]