TECHNOLOGY VLSI SYMPOSIUM III-Vs prepare to replace silicon


Record mobilities, production processes on 300 mm silicon and impressive nanometre-scale performance indicate that III-V MOSFETs are getting closer to enter production


RICHARD STEVENSON REPORTS


FOR MANY YEARS, pundits have argued that the shrinking of silicon is about to come to an end. Often, though, thanks to unforeseeable innovations by the engineers in the labs and fabs, obstacles have been overcome and the march of Moore’s Law has prevailed.


But now, arguably more than ever before, it seems that the days of silicon really are numbered. After all, why else would the silicon heavyweight IBM agree to pour $3 billion into the development of new technologies, including post-silicon materials for the 7 nm node and beyond?


The leaders of IBM view several materials as possible successors to silicon, including compound semiconductors. III-Vs sport high electron mobility, and if they could be used in the channel of post-silicon MOSFETs, they would enable devices to deliver a high current at a lower operating voltage. This would ultimately underpin a trimming of the power per transistor as size is reduced, one of the trends associated with Moore’s Law that is now under threat.


Efforts at developing compound semiconductor MOSFETs were discussed at the most recent VLSI Symposium, which was held in Honolulu, Hawaii, from 9-13 June 2014. At this


Figure 1. Researchers from KANC, working in partnership with those at Yonsei University, Sematech and GlobalFoundries, produced a MOSFET with a gate-last process that delivered an effective mobility of more than 5500 cm2


V-1 s-1 . 50 www.compoundsemiconductor.net Issue VI 2014 Copyright Compound Semiconductor


meeting a team headed by researchers at the Korea Advanced NanoFab Centre (KANC) claimed a new record for mobility in a III-V MOSFET; engineers from imec reported the development of foundry-compatible process for making compound semiconductor finFETs on 300 mm silicon; and a team led by researchers at the University of California, Santa Barbara (UCSB), claimed to have produced the first III-V MOSFETs that can match or exceed those of production


silicon devices, while being constructed at dimensions relevant to the VLSI industry.


Record mobilities Researchers at KANC, working in partnership with those at Yonsei University, Sematech and GlobalFoundries, announced at the conference a claim for record effective mobility of more than 5500 cm2


V-1 Ga0.3 As channel. s-1 ,


using a III-V MOSFET incorporating an In0.7


Chan-Soo Shin from KANC, speaking on behalf of the team, attributes the record to a combination of a high- indium-content InGaAs channel, MOCVD selective source and/or drain re-growth, and a gate-last integration scheme.


By employing a gate last process, the heart of the device is not subjected to high temperatures.


“Unlike silicon, the interface quality of an oxide-and-indium-gallium arsenide interface tends to be easily deteriorated when it experiences processes with temperatures above 500 °C,” says Shin. Such temperatures are common in the conventional gate-first approach, with source and drain implantation-activation typically taking place at more than


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160