US 12,224,352 B2
Transistor including an active region and methods for forming the same
Wu-Wei Tsai, Hsinchu (TW); Hai-Ching Chen, Hsinchu (TW); and Po-Ting Lin, Hsinchu (TW)
Assigned to Taiwan Semiconductor Manufacturing Company Limited, Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Company Limited, Hsinchu (TW)
Filed on Sep. 20, 2021, as Appl. No. 17/479,844.
Claims priority of provisional application 63/178,128, filed on Apr. 22, 2021.
Prior Publication US 2022/0344510 A1, Oct. 27, 2022
Int. Cl. H01L 29/66 (2006.01); H01L 29/423 (2006.01); H01L 29/786 (2006.01)
CPC H01L 29/7869 (2013.01) [H01L 29/42356 (2013.01); H01L 29/66969 (2013.01); H01L 29/78648 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A transistor comprising:
an active layer located over a substrate and including a compound semiconductor material comprising oxygen, at least one acceptor-type element, and at least one heavy post-transition metal element, wherein each of the at least one acceptor-type element is selected from a group consisting of gallium (Ga) and tungsten (W), wherein each of the at least one heavy post-transition metal element is selected from a group consisting of indium (In) and tin (Sn), and wherein an atomic percentage of the at least one heavy post-transition metal element at a top surface of the active layer is higher than an atomic percentage of the at least one heavy post-transition metal element at a bottom surface of the active layer; and
a top gate stack comprising a top gate dielectric straddling the active layer and a top gate electrode located on a top surface of the top gate dielectric,
wherein the active layer comprises a vertical stack of a front channel layer in contact with the top gate dielectric, a back channel layer comprising a bottom surface of the active layer, and a bulk semiconductor layer located between the front channel layer and the back channel layer;
wherein one of the front channel layer, the back channel layer, and the bulk semiconductor layer comprises an inhomogeneous compound semiconductor material having a vertical composition gradient such that an atomic concentration of the at least one acceptor-type element decreases continuously throughout said one of the front channel layer, the back channel layer, and the bulk semiconductor layer with a vertical distance from the substrate, and an atomic concentration of the at least one heavy post-transition metal element increases continuously throughout said one of the front channel layer, the back channel layer, and the bulk semiconductor layer with the vertical distance from the substrate; and
wherein another of the front channel layer, the back channel layer, and the bulk semiconductor layer comprises a homogeneous compound semiconductor material having a uniform material composition throughout.