An approach for uniting bottom-up and top-down systems and its applications
Abstract
We have investigated the possibility of creating a unification platform for top-down systems and bottom-up structures, which is one of the most important issues for harvesting fruits of upcoming nano-technologies and nano-science together with those of Si- LSI-based information technologies. Under the device-approach, for unifying bottom-up and topdown systems, proposed is a functional device that has hierarchical structures grown, or is to have hierarchical structures grow, inside, not as a result of top-down designing but as a result of self-organization, i.e., a bottom-up structure-formation. Spiral heterostructure is of potential interest for providing us with one-dimensional superlattice structure that would serve as a bridge between top-down LSI systems with two-dimensional bottom-up structures. The spiral heterostructure is, also, of importance for enabling multi-striped orthogonal photon-photocarrier-propagation solar cell (MOP3 SC). On the other hand, as a tool-based approach, for unifying bottom-up and top-down systems, clean unit system platform (CUSP) is developed. CUSP can realize dust- and microbe-free environment. The clean versatile environments having small footprint, low powerconsumption and high cost-performance can be realized with CUSP for the next generation production system as well as for cross-disciplinary experiments. The approach for uniting bottom-up and top-down systems gives not only new devices but also clean platforms that would be able to serve as clean space for all of us.
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Introduction
A possible platform that unites, or makes a bridge over the gap between, the top-down systems such as Si-based LSIs, for which lithography plays vital roles, and bottom-up systems like self-organized or self-assembled systems will surely be able to enjoy as huge a success as the string theory does, because of its full seamless line-up of highly structured materials. First, we have to overcome the sharp contrast lying between the top-down system, the structure of which is fabricated globally through man-made design from outside by so-called processing, and the bottom-up system, for which the structure, on the other hand, is determined autonomously through the local interactions described by non-equilibrium diffusion equations, etc. Study of the possibility of creating a unification platform for bottom-up and top-down systems is one of the most important issues, in future, for harvesting the fruits of upcoming nano-technologies and nano-science together with those of Si-LSIbased information technologies.
Conventional mainstream functional devices are those manufactured by a top-down approach based upon micro-fabrication, as represented by semiconductor integrated circuits. Especially regarding semiconductor devices, huge semiconductor electronics industry has been established, via inventions of transistors [1], and inventions of semiconductor integrated circuits [2,3]. On the other hand, the top-down approach begins to see delimitation in various points. As a technique that breaks the limit, a bottom-up approach by self-organization, etc. has been remarked and studied actively. Both cell systems and neuron systems have been reported to continuously expand and grow by autonomous dispersion at individual sites [4]. This is classified as bottom-up systems. In bottom-up systems, individual portions independently build structures according to local rules or interactions that lead to autonomous decentralized systems. It has been demonstrated by using cellular automaton that there are four different types of structure-building schemes (constant, periodically laminated [nested], functionally structured, and random) with respect to time [5]. Also with respect to time, especially based upon the concept of time projection, we have reported an improvement of a time projection chamber (TPC) as an elementary particle detector using secondary electrons continuously moving with time (electrons generated along trajectories of elementary particles), based on constancy of the drift velocity [6]. On the other hand, it has also been reported that resolution of a one-atomic layer in the growth direction is obtained in growth of a semiconductor using metal organic chemical vapour deposition (MOCVD) [7].
Conclusion
As shown in Fig. 13, just like the string theory which enjoys explaining things seamlessly from large scale structures in universe to small entities with Planck scale by resolving the disaccord between the theory of relativity and the quantum theory, a possible platform that unites, or makes a bridge over the gap between, the top-down systems such as Si-based LSI’s and bottom-up systems like self-organized or self-assembled systems will surely be able to enjoy as huge a success as the string theory does, because of its full seamless line-up of highly structured materials. First, we have to overcome the sharp contrast lying between the top-down system, whose structure is fabricated globally through man-made design from outside by so-called processing, and the bottom-up system, for which the structure, on the other hand, is determined autonomously through the local interactions described by non-equilibrium diffusion equations, etc. We have studied the possibility of creating a unification platform for bottom-up and top-down systems, which, as shown in Fig. 13, is one of the most important issues, in future, for harvesting fruits of upcoming nano-technologies and nano-science together with those of Si-LSI-based information technologies.
Under the device based approach, for unifying bottom-up and top-down systems, proposed is a functional device that has hierarchical structures grown, or is to have hierarchical structures grow, inside, not as a result of top-down designing but as a result of self-organization, i.e., a bottom-up structure-formation. Such structure could be formed quite universally in many systems as long as they have inflow of energy as well as spatio-temporal dissipation. As already shown above, one of them is the pn-junction system, with which one can make an electronically controllable, self-similar, fractal (nested) structure, in a fully solid state system exploiting self-organized criticality induced by carrier injection and non-radiative recombination. What is demonstrate here, we believe, is to make otherwise inaccessible self-organized structures accessible, for the first time, in a fully solid state system, through electronic means that have huge affinity to established semiconductor electronics. The self-similar, nested, hierarchical structures are to emerge from the pre-existing defects spreading throughout the active region when carriers are injected enough. Such hierarchical structure, being supported by energy inflow and dissipation there, could be made not only in inorganic but also in organic or bio-related materials. As described above, according to the presented framework, it would be possible in near future to realize a sophisticated functional device that can make the best use of advantages of bottom-up systems and top-down systems represented by silicon LSI. Under the tool-based approach, for unifying bottom-up and top-down systems, clean unit system platform (CUSP) is developed. The clean versatile environments having small footprint, low power-consumption and high cost-performance can be realized with CUSP for the next generation production system as well as for cross-disciplinary experiments. Multiply-connected CUSP system based upon those would serve as the platform not only for nano-technologies or bio-technologies but also for the next-generation environment-friendly platform for industries. In terms of small footprint, low power-consumption and high costperformance, CUSP in its full line-up could outperform a conventional super cleanroom (“main frame”) and would be the cleanroom for all of us.
The author express sincere thanks to Drs. Y. Mori, S. Tomiya, S. Ito, K. Nakano, H. Okuyama, K. Kondo, and H. Kaiju for fruitful discussions, This work is supported, in part, by Special Education & Research Expenses from Post-Silicon Materials and Devices Research Alliance, JST Seeds Innovation Program, Post-Silicon Materials and Devices Research Alliance, Nano-Macro Materials, Devices and System Research Alliance, and 2010-2012 Grant-in-Aid for Scientific Research (B) [22350077], 2013-2015 Grant-in-Aid for Scientific Research (B) [25288112], 2016-2018 Grant-in-Aid for Scientific Research (B) [16H04221], and 2016-2017 Grant-in-Aid for Challenging Research (Exploratory) [16K12698] from the Japan Society for the Promotion of Science (JSPS).