Route to high-precision positioning of single ion-implanted impurities in silicon

硅中单离子注入杂质的高精度定位之路

基本信息

批准号：
EP/X018989/1
负责人：
Steven Clowes
金额：
$ 23.8万
依托单位：
University of Surrey
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2023
资助国家：
英国
起止时间：
2023 至无数据
项目状态：
未结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FX018989%2F1
关键词：
Route precision positioning single ion

项目摘要

The only quantum technology (QT) fabrication technology that can readily leverage microelectronic fabrication processes with the existing ability of large scale-up, enabling big enough qubit arrays for error correction, or that can potentially repeatably manufacture large numbers of identical devices, is the incorporation of single impurity qubits through implantation. However, unless fully deterministic implantation of single ions (ISI) is developed, the advantages of impurity-based QT for scale-up will not be realized. Quantum computing based on ion traps, superconducting circuits and semiconductor quantum dots using a small number of qubits are well advanced, but very large-scale reproduction constitutes a major challenge for each. Small numbers of impurity qubits in silicon can also be made with high quality using hydrogen lithography, which is based on scanning probe techniques, that have enabled atomic-scale precision leading to such ground-breaking achievements as the single-atom transistor (However, it is slow and does not provide an easily scalable route to the millions of qubits needed for manufacturable quantum computers. Implantation in silicon of single impurity qubit atoms offers a solution, but most of the research in this area centres on samples with stochastic incorporation of impurities with some limited control over the placement through masks or with focussed beams. The challenge here is therefore the opposite compared with ion traps etc - large scale repetition is easy, but the positioning (and consequent error rate) of each qubit is poorer and must be improved. The placement precision is limited by the focusing of the implanted ion and the movement of the ion after it enters the target material, known as the impact straggle. Implantation also causes undesirable damage to the crystal host, as the energetic ion ricochets through channels in the crystal. This is the challenge we seek to address, using a speculative idea that will not only repair this impact damage cloud but also, and most importantly, allow much higher precision positioning of the implanted impurity. We propose a solution based on lateral solid phase epitaxial regrowth (L-SPER). Simply put, the target area is pre-amorphised (implanting silicon ions into silicon breaks bonds but does not introduce impurities and can even improve isotopic purity) by a focussed ion beam or through broad area lithography and ion implantation. Following implantation of a single ion, a low-temperature anneal restores the crystal through epitaxial regrowth, which is seeded by the surrounding crystalline material. Full pre-amorphisation is well known to result in higher crystallinity following annealing, compared to the partial amorphisation caused solely by the implantation process. The nature of this proposal is to consider what effect L-SPER has on an individual implanted atom. There is every reason to expect that, as the amorphised region shrinks during regrowth, the impurity atom is slowly pushed to the centre as the crystal reforms. If we can demonstrate this, then the precision of the final placement of the atom may be affected more strongly by the central positioning of the pre-amorphised regions rather than limited by the focusing uncertainty and straggle of the implanted ion, where the former can be of the order of a nanometer giving an order of magnitude improvement in the final positioning.

唯一可以轻松利用微型制造过程的量子技术（QT）制造技术，具有大规模扩大的现有能力，可以使足够大的量子阵列进行错误校正，或者可以通过植入通过植入来重复生产大量相同的设备。但是，除非开发单个离子（ISI）的完全确定性植入，否则将无法实现基于杂质的QT的优势。基于离子陷阱，超导电路和使用少量Qubits的半导体量子点的量子计算非常先进，但是非常大的繁殖构成了每个量子的主要挑战。 Small numbers of impurity qubits in silicon can also be made with high quality using hydrogen lithography, which is based on scanning probe techniques, that have enabled atomic-scale precision leading to such ground-breaking achievements as the single-atom transistor (However, it is slow and does not provide an easily scalable route to the millions of qubits needed for manufacturable quantum computers. Implantation in silicon of single impurity qubit原子提供了一种解决方案，但是该区域的大多数研究集中在杂质的随机掺入中，对通过口罩的放置或焦距有限的控制有限。离子进入目标材料后的离子，称为撞击。作为通过晶体中的通道，植入也会对晶体宿主造成不良损害。这是我们寻求应对的挑战，它使用一个投机性的想法，该想法不仅可以修复这种影响损害云，而且还可以，最重要的是，允许更高的植入杂质定位。我们提出了一个基于侧面固相外延再生（L-SPER）的溶液。简而言之，目标区域是预先塑造的（将硅离子植入硅断裂键，但不会引入杂质，甚至可以通过聚焦离子束或通过宽面积光刻和离子植入来提高同位素纯度）。植入单个离子后，低温退火通过外延再生恢复晶体，该再生由周围的晶体材料播种。与仅由植入过程引起的部分无形化相比，众所周知，完全的预性会导致退火后更高的结晶度。该提议的性质是考虑L-SPER对个体植入原子的影响。有充分的理由可以期望，随着无形区域在再生期间的缩小，随着晶体改革的速度，杂质原子被慢慢推向中心。如果我们能够证明这一点，那么原子的最终放置的精度可能会受到预先不形式的区域的中心定位的影响，而不是受植入离子的注意力不确定性和散布的限制，而前者可以在最终位置的纳米表中取得纳米计的顺序提高。