Research on mobility variance caused by TSV-induced mechanical stress in 3D-IC

Abstract

Due to mismatch in the coefficients of thermal expansion of silicon and copper, mechanical stresses in surrounding silicon are induced near TSV in 3D ICs. In this paper, the mobility variance of substrate material caused by TSV-induced stress is researched. Firstly the semi-analytical model for TSV-induced stress distribution is introduced. An analytical model for TSV-induced stress distribution is then developed base on the semi-analytical model with curve fitting method. At last, a mobility variance model is obtained combining with piezoresistive effect theory. The influence of TSV diameter, distance to TSV, crystal orientation, carrier type, and the difference of CTEs on mobility variance are analyzed based on the mobility variance model. Keywords-3D IC; TSV-induced stress; piezoresistive effect; mobility variance modelI.

Shallow trench isolation structure design for through‐silicon vias stress reduction

“…Compared with the many areas that need to be reserved without STI, the existence of STI is insignificant and can improve the integration of three‐dimensional integrated circuits. The relationship between the change of carrier mobility and stress can be expressed as 22 Among them, represents the radial thermal stress, β ( θ ) orientation factor is shown in Table 1, and θ is the angle between the thermal stress and the transistor channel. θ of 0°and 90°, respectively mean that the introduced transistor channel is parallel or perpendicular to the radial stress.…”

“…Compared with the many areas that need to be reserved without STI, the existence of STI is insignificant and can improve the integration of three-dimensional integrated circuits. The relationship between the change of carrier mobility and stress can be expressed as 22…”

Effect of annealing residual stress on mobility of TSV vertical switch

“…During the fabrication of the TSV, thermal stress is generated around the TSV after thermal annealing due to the different thermal expansion coefficients of various materials [14,15,16,17,18,19]. Mobility is a function of stress, and even if stress does not have a destructive effect on the structure, it can affect the mobility of the substrate device, which in turn affects the overall performance [20,21,22,23]. Current studies on thermal stresses induced by TSV have focused on the surface of the silicon substrate around the TSV [24,25,26,27].…”