環型佈植角度對奈米MOSFET數位及類比特性的影響

Influence of Pocket Implant Angles on Digital and Analog Performances of Nano-MOSFETs

林文政(Wen-Cheng Lin)

指導教授 ： 黃恆盛 ； 陳雙源

國立臺北科技大學/機電學院/機電整合研究所/碩士(2006年)

摘要

一般使用於邏輯製程之金氧半場效電晶體(MOSFET)的環型佈植，通常會使其於類比電路中降低性能。但有研究發現，使用越濃的環型佈植於短通道元件，能同時提升數位與類比的效能，而造成此兩者性能提升的原因，主因為元件尺寸的微縮，環型佈植已使通道下的濃度結構轉變成均勻分布。進一步推論，如果元件尺寸持續微縮至奈米區域，甚至可能會形成通道中間濃度較高的環型佈植結構，因此，本研究透過建立不同的通道濃度結構來比較其對元件的類比與數位特性；進而提升類比與數位電路整合在同一個晶片的製程裕度，而達到節省成本，增加競爭力的目的。並期待此研究於混合信號(mixed-signal)應用時，元件設計人員能調製出更滿足類比與數位電路需求的元件。
基於實際應用量產成本考量，本篇論文透過環型佈值的角度變化來達成3種通道濃度結構，即小角度(15°)、中角度(30°)以及大角度(40°)環型佈植形成的通道濃度結構，並分別命名為M型、F型以及A型。此外，本研究也將硼與氟化硼(BF2)環型佈植的差別加以討論。比較M型、F型和A型在較短通道長度時，A型有相反的短通道效應，可以有效抑制漏電流，尤其是A型配合氟化硼環型佈植，最適合做低待機功率(LSTP)元件之應用。而M型的短通道效應相較之下雖然稍為嚴重，但有著較好的類比元件性能，尤其是M型配合硼環型佈植最適合做類比元件的應用。F型配合氟化硼環型佈植則適合做數位元件的應用。

關鍵字

汲極工程 ； 類比元件設計 ； 硼 ； 氟化硼 ； 環型佈植

並列摘要

Pocket or halo implant is commonly used in the process of high performance logic CMOS technology in order to control the short channel effect (SCE) of MOSFETs. But, it is believed that the implant also degrades the MOSFETs’ analog performance such as early voltage (VA) and output resistance (Rout). However, our previous research revealed that that heavy pocket implant can improve the Rout and VA of very short channel nMOSFETs because the implant has generated laterally flat doping concentration along the channel. Accordingly, it is necessary to thoughtfully investigate what analog and digital characteristics the MOSFETs will generate in respect to the different lateral doping profiles constructed by different pocket implants.
To implement above motivation, ISE TCAD simulation in cooperation with UMC 90 nm node experimental data were performed in this research. To be specific, three channel doping profiles named M, F and A types were constructed by using small (15°), medium (30°) and large (40°) pocket implant angles, respectively. Differences of using species of boron and BF2 were also included in this research after analyzing the simulation results, it is found that A type can suppress off-state current but can cause serious reverse short channel effect (RSCE). Therefore, A type is recommended suitable for low standby power (LSTP) applications. M type shows excellent analog performance in comparison with other two types, especially for M type with boron species, which is recommended most suitable for analog circuits. As for the F type, the simulation shows it applicable to digital devices. Finally, the probable best choice for mixed-signal applications is using boron pocket implant though choosing appropriate pocket implant angles between small and medium. Thus, the device may not need trade-off at short channel region when facing both analog and digital requirements.

並列關鍵字

Drain engineering ； Analog device design ； Boron ； BF2 ； Pocket

參考文獻

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