Systematic study of RTN in nanowire transistor and enhanced RTN by hot carrier injection and negative bias temperature instability

Abstract

We experimentally study the random telegraph noise (RTN) in nanowire transistor (NW Tr.) with various widths (W), lengths (L), and heights (H). Time components of RTN such as time to capture (τ c ) and emission (τ e ) are independent of NW size, while threshold voltage fluctuation (ΔV th ) by RTN can be well fitted with 1/{L(W+2H)} 0.5 corresponding to the conventional carrier number fluctuations regardless of the side surface orientation. Hot carrier injection (HCI) and negative bias temperature instability (NBTI) induced additional carrier traps leading to the increase in the number of observed RTN. Moreover, ΔV th is enhanced by HCI and NBTI and enhancement of ΔV th becomes larger in narrower W. IntroductionRTN caused by the carrier trap becomes a crucial issue in nano-scaled Tr. So far, RTN in NW Tr. has been reported [1]. Most of the reported RTN in NW Tr. were focused on each capture and emission behavior and often suggested the quantum confinement effect. However it is necessary to measure a number of RTN in order to conclude whether RTN in NW Tr. can be explained by the conventional size dependence as planar Tr. or not. Furthermore, it was reported that HCI and BTI, which are also the issues for reliabilities, induced the additional traps generating RTN [2,3]. Since HCI and NBTI degradations are enhanced in NW Tr. [4,5], RTN after HCI and NBTI should be investigated.In this work, we measured the NW size dependence and the side surface orientation dependence of RTN with a number of ment of Nanoelectronic Device Technology. The authors thank Dr. J.Chen for technical support.

Trigger-When-Charged: A Technique for Directly Measuring RTN and BTI-Induced Threshold Voltage Fluctuation Under Use-<inline-formula> <tex-math notation="LaTeX">${V}_{dd}$ </tex-math> </inline-formula>

“…As mentioned in the introduction, early works [6][7][8][9][10] often estimated ΔVth by ΔId/gm(Vdd), where both ΔId and gm were obtained under Vg=Vdd. This is effectively measuring the shift of IV at Vg=Vdd, as marked by the point 'B' in Fig.…”

“…The increased number of devices per chip also leads to larger statistical spread [1,2] and high data transmission rate requires tight control of fluctuations [3]. Fluctuations have become a major concern for circuit design and have attracted many attentions recently [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. It has been reported that current fluctuation in some fresh devices can be over the typical device lifetime criterion of 10% [5].…”

“…Fluctuations are commonly observed as the random telegraph noise (RTN) in the drain current, ΔId, under a given evaluated in this way was not given in these works [6][7][8][9][10].…”

An assessment of RTN-induced threshold voltage jitter

“…The instabilities of modern MOSFETs have a number of sources: bias temperature instabilities (BTI) [1][2][3][4][5][6][7], hot carrier ageing (HCA) [8][9][10], and random telegraph noise [11][12][13][14][15][16][17]. To increase the instabilities and make them measurable, it is a common practice to use voltage-acceleration [1][2][3][4][5][6][7][8][9][10].…”

“…At a pre-specified time, they can be neutral and would be missed if the MSM technique is used. Because of these difficulties, early works [12,13] focus on measuring the fluctuation in drain current, ΔId, under a fixed Vg. This on-the-fly (OTF) ΔId is then converted to ΔVth by dividing the transconductance, gm.…”