Low Frequency Noise Analysis of Impact of Metal Gate Processing on the Gate Oxide Stack Quality

Abstract

A review is given about the impact of the metal gate (MG) in a High-κ/Metal Gate (HKMG) stack on the quality and defectivity of the dielectric, assessed by low-frequency (LF) noise spectroscopy. In a first part, processing aspects are discussed, like, the thickness of the MG and the implementation of a gate-last approach. In the latter case, it is shown that both the cleaning (or dummy gate removal), the growth of the interfacial SiO 2 layer (chemical versus thermal) and a post-HfO 2 -deposition heat or SF 6 plasma treatment need to be optimized for reducing the gate oxide trap density. In a second part, different MGs are compared from a viewpoint of noise magnitude. It is generally found that alternatives to the standard TiN gate yield better static and noise performance. Results will be presented both for scaled planar and FinFET technologies; the latter fabricated on either bulk or Silicon-on-Insulator (SOI) substrates. Also results on Gate-All-Around NanoWire FETs (GAA NWFETs) fabricated on SOI will be included.

Low-Frequency Noise Assessment of Work Function Engineering Cap Layers in High-k Gate Stacks

“…itself as the impact of this parameter on the 1/f noise performance has recently been reviewed by the authors. [21][22][23]…”

“…itself as the impact of this parameter on the 1/f noise performance has recently been reviewed by the authors. [21][22][23] Trap density.-In the case that the noise is dominated by carrier number fluctuations (CNF or n), i.e., capturing/emission of carriers by/from traps in the dielectric, the trap density N ot can be calculated from the 1/f noise PSD using: 15,16,24…”

PBTI stress-induced 1/f noise in n-channel FinFET*

“…[5][6][7][8] As is well known, the gate oxide quality and reliability strongly depend on the type of high-k material and the interfacial oxide layer. [9] The measuring of low-frequency noise also known as 1/ f noise is usually used as a non-destructive technique for evaluating the quality of the oxide-semiconductor interface and channel layers. [10,11] Many studies reported in the literature have pointed out that carrier number fluctuation (∆n) and correlated mobility fluctuation (∆µ) are the main physical mechanisms that give rise to the 1/ f noise phenomena.…”