Wafer Direct Bonding_ From Advanced Substrate Engineering- t

很好的一篇有关晶圆键合技术的综述文章。

Wafer Direct Bonding:From AdvancedSubstrateEngineering to Future Applications in Micro/Nanoelectronics

Techniques for strong bonding of brittle semiconductor wafers are opening the way to production of nanometer circuits on insulator substrates and to fabrication of micro/nano sensors and actuators.

By Silke H.Christiansen,Rajendra Singh,and Ulrich Go¨sele

B In memory of Qin-Yi Tong who significantly advanced the field of wafer bonding.[

ABSTRACT|Wafer direct bonding refers to the process of adhesion of two flat mirror-polished wafers without using any intermediate gluing layers in ambient air or vacuum at room temperature.The adhesion of the two wafers occurs due to attractive long range van der Waals or hydrogen bonding forces.At room temperature the bonding energy of the in-terface is low and higher temperature annealing of the bonded wafer pairs has to be carried out to enhance the bonding energy.In this paper,we describe the prerequisites for the wafer-bonding process to occur and the methods to prepare the suitable surfaces for wafer bonding.The characterization techniques to assess the quality of the bonded interfaces and to measure the bonding energy are presented.Next,the applications of wafer direct bonding in the fabrication of novel engineered substrates such as B silicon-on-insulator[and other B on-insulator[substrates are detailed.These novel sub-strates,often called hybrid substrates,are fabricated using wafer bonding and layer splitting via a high dose hydrogen/ helium implantation and subsequent annealing.The specifics of this process,also known as the smart-cut process,are in-troduced.Finally,the role of wafer bonding in future nano-technology applications such as nanotransistor fabrication, three-dimensional integration for high-performance micro/ nanoelectronics,nanotemplates based on twist bonding,and nano-electro-mechanical systems is discussed.

KEYWORDS|Bonded interface;bonding energy;complemen-tary metal–oxide semiconductor(CMOS);hybrid substrates;layer transfer;micro-/nano-electro-mechnical systems(M/NEMS); micro/nanoelectronics;silicon-on-insulator(SOI);smart cut; strained silicon-on-insulator(sSOI);twist bonding;wafer direct bonding

I.INTRODUCTION

The technology of wafer direct bonding has made signi-ficant advances over the last decade.Consequently,there is an extensive and rapidly expanding body of literature on all aspects of wafer direct bonding.It is beyond the scope of this overview to cover all facets of wafer bonding.For deeper insights and a more exhaustive bibliography,the reader is referred to textbooks and reviews[1]–[7].

The objective of this overview is to present the basic and essential features of wafer direct bonding in Section II

Manuscript received August1,2005;revised August1,2006.This work was supported

in part by BMBF,in part by DFG,and in part by the State of Saxony-Anhalt.

S.H.Christiansen was with the Max Planck Institute of Microstructure Physics,

D-06120Halle,Germany.She is now with the Physics Department,Martin Luther

University,D-06099Halle,Germany(e-mail:christianen@mpi-halle.de).

R.Singh was with the Max Planck Institute of Microstructure Physics,D-06120Halle,

Germany.He is now with the Department of Physics,Indian Institute of Technology

of Delhi,New Delhi110016,India(e-mail:rsingh@mpi-halle.de).

U.Go¨sele is with the Max Planck Institute of Microstructure Physics,D-06120Halle,

Germany(e-mail:goesele@mpi-halle.de).

Digital Object Identifier:10.1109/JPROC.2006.886026

2060Proceedings of the IEEE|Vol.94,No.12,December20060018-9219/$20.00Ó2006IEEE

很好的一篇有关晶圆键合技术的综述文章。

after a short general introduction in Section I to allow the reader to understand the latest and most remarkable advances and applications of wafer direct bonding that will be presented and discussed in Sections III and IV.The present overview does not address specific applications in the area of micromechanics since there are excellent reviews available on this subject[4]–[6],[8]–[10].Never-theless,many basic features mentioned here are also ap-plicable and relevant in this area.

A.What is Wafer Direct Bonding?

B Wafer direct bonding[also simply termed B wafer bonding[or B fusion bonding[refers to the adhesion of two solids with sufficiently clean and preferably almost ideally flat surfaces[1]–[13].These surfaces adhere by attractive forces without the use of any adhesive layers or the application of external forces.Wafer direct bonding relies on the understanding of micro-and nanoscopic physical and chemical effects at the bond interface.Standard wafer bonding of silicon wafers in air is attributed to relatively weak intermolecular attractive forces,such as van der Waals forces or forces associated with hydrogen bridge bonds;see,e.g.,[4],[6],and[14].Subsequent annealing at elevated temperatures is required to achieve much higher bond strengths as they are required for most tech-nological applications.Prior to annealing,the bonding is still reversible with bonding energies in a typical range of 10–100mJ/m2and occurs irrespective of the materials structure or composition,no matter whether the material is single or poly-crystalline or amorphous and no matter whether the material is single phase or of composite nature.This means all materials should,in principle,be bondable initially in a reversible fashion as long as they meet the respective requirements in surface roughness, flatness,and cleanliness.The transformation into strong bonds(with bonding energies exceeding1000mJ/m2) depends on the detailed materials chemistry at the in-terfaces and has to be considered inpidually for each case of bonding of a wafer of one material to a wafer of the same or a different material.In principle,in the case of ductile materials,mutual con …… 此处隐藏：58244字，全部文档内容请下载后查看。喜欢就下载吧 ……