Detection of nitrogen related traps in nitrided/reoxidized silicon dioxide films with thermally stimulated current and maximum entropy method

Abstract

We constructed the new method to analyze thermally stimulated current (TSC) using maximum entropy method. This method allows us to extract trap density depending on trap energy level [Nt(Et)] from a TSC curve. Using this to analyze TSC of as-deposited, nitrided, and reoxidized thin silicon dioxide films, we were able to determine Nt(Et) of hole traps with very highly energy resolution and to observe the generation of nitrogen related hole traps.

Application of Maximum Entropy Method to Semiconductor Engineering

“…Very recently, MEM was applied to TSC data to determine the density (N t ) and energy level (E t ) of traps in SiON thin films [22,23]. The results evidenced that MEM provides detailed N t (E t ) distribution and even its compositional dependence.…”

“…• C) and cannot investigate the interface states (D it ) located at the interface between a gate insulator and underlying substrate [22,23]. The IA technique can be used to overcome these difficulties though it is easy and simple, and requires no complex equipment or measurement system.…”

“…For this case β =20 K/min and ν = 10 11 /s were assumed [22][23][24]. The assumed N t (E t ) distribution is shown in Figure 7a (peaks A, B, and C).…”

“…Equation (16) has the same shape as Equation (1); however, N t (E t ) is not a probability density function and does not satisfy Equation (2). In order to overcome this difficulty, I TSC (T ) and N t (E t ) must be normalized with the normalized constant P as the next equations [22,23] …”

“…On the other hand, there have been few reports on MEM usage other than for ARXPS data analysis [22][23][24][25]. Semiconductor device characteristics are affected not only by specific atom or chemical species distributions, but also by traps, interface states, and fixed charges present inside films and/or at interfaces between the gate insulator and substrate.…”