A remarkable feature of modern silicon electronics is its ability to remain functionally and physically invariant, almost indefinitely for many practical purposes. Here, we introduce a silicon-based technology that offers the opposite behavior: it gradually vanishes over time, in a well-controlled, programmed manner. Devices that are ‘transient’ in this sense create application possibilities that cannot be addressed with conventional electronics, such as active implants that exist for medically useful timeframes, but then completely dissolve and disappear via resorption by the body. We report a comprehensive set of materials, manufacturing schemes, device components and theoretical design tools for a complementary metal oxide semiconductor (CMOS) electronics of this type, together with four different classes of sensors and actuators in addressable arrays, two options for power supply and a wireless control strategy. A transient silicon device capable of delivering thermal therapy in an implantable mode and its demonstration in animal models illustrate a system-level example of this technology.

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Polyurethane (PU) pad debris is identified as one of the major polish residue defects in Cu CMP processes when a barrier pad is conditioned. AES analysis of the debris confirms the organic nature of such defects while FT-IR analysis reveals the characteristic peaks of polyurethane from the pad debris. Hybrid cleans (i.e. acidic plus basic cleans) and basic cleans can both remove the pad debris effectively. The efficiency of basic-only cleans can be improved by increasing time and/or chemistry concentration in the brush modules. The PU pad can endure harsh chemical environments at both low and high pH without any detectable decomposition or morphological changes. The advantages and disadvantages of acidic vs. basic cleans are discussed and the cleaning mechanisms of pad debris PR are elucidated.

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