A method includes forming an active region on a substrate, forming a sacrificial gate stack engaging the active region, measuring a gate length of the sacrificial gate stack at a height lower than a top surface of the active region, selecting an etching recipe based on the measured gate length of the sacrificial gate stack, etching the sacrificial gate stack with the etching recipe to form a gate trench, and forming a metal gate stack in the gate trench.

There is provided a semiconductor device including: a drift region of a first conductivity type disposed in a semiconductor substrate; a base region of a second conductivity type disposed above the drift region; an emitter region of the first conductivity type disposed above the base region; a plurality of trench portions arrayed in a predetermined array direction on a front surface side of the semiconductor substrate; a trench contact disposed on the front surface side of the semiconductor substrate between two adjacent trench portions; and a contact layer of the second conductivity type disposed under the trench contact and having a higher doping concentration than the base region, wherein a lower end of the trench contact is deeper than a lower end of the emitter region, and the emitter region and the contact layer are in contact with each other at a side wall of the trench contact.

A semiconductor device 1 has an electrode structure that includes source electrodes 3, a gate electrode 4, and drain electrodes 5 disposed on a semiconductor laminated structure 2 and extending in parallel to each other and in a predetermined first direction and a wiring structure that includes source wirings 9, drain wirings 10, and gate wirings 11 disposed on the electrode structure and extending in parallel to each other and in a second direction orthogonal to the first direction. The source wirings 9, the drain wirings 10, and the gate wirings 11 are electrically connected to the source electrodes 3, the drain electrodes 5, and the gate electrode 4, respectively. The semiconductor device 1 includes a conductive film 8 disposed between the gate electrode 4 and the drain wirings 10 and being electrically connected to the source electrodes 3.

A semiconductor device includes a semiconductor layer made of SiC. A transistor element having an impurity region is formed in a front surface portion of the semiconductor layer. A first contact wiring is formed on a back surface portion of the semiconductor layer, and defines one electrode electrically connected to the transistor element. The first contact wiring has a first wiring layer forming an ohmic contact with the semiconductor layer without a silicide contact and a second wiring layer formed on the first wiring layer and having a resistivity lower than that of the first wiring layer.

The trench structure part includes a field plate electrode, a first insulating film, a second insulating film, the second insulating film extending to be more proximate to the first surface than the first insulating film, a gate electrode including a first portion located on the second insulating film, and a second portion located on the first insulating film, the second portion being thicker than the first portion, and a third insulating film. The gate contact part extends from the gate wiring layer toward the second portion and contacts the second portion. The gate contact part is not positioned between the first portion and the gate wiring layer. The first portion is positioned adjacent, in a second direction orthogonal to the first direction, to a lower end portion of the gate contact part contacting the second portion.

The gate electrode includes a first side surface portion facing a region of a side surface of a mesa part, a second side surface portion positioned at a side opposite to the first side surface portion, a bottom portion oblique to the first and second side surface portions, the bottom portion connecting the first side surface portion and the second side surface portion, a first corner portion positioned between the first side surface portion and the bottom portion, and a second corner portion positioned between the second side surface portion and the bottom portion. An angle between a first straight line and a second straight line is not more than 60. The first straight line is a straight line extending in a first direction and passing through the first corner portion. The second straight line is a straight line passing through the first and second corner portions.

A field plate electrode FP and a gate electrode GE are formed inside a plurality of trenches TR1. An outer peripheral trench TR2 surrounds the plurality of trenches TR1 in plan view. A field plate electrode FP (lead-out portion FPa) is formed inside the outer peripheral trench TR2. The outer peripheral trench TR2 has an extending part TR2a extending in the Y direction, an extending part TR2b extending in the X direction, and a corner part TR2c extending in a direction different from the X and Y directions in plan view and connecting the extending part TR2a and the extending part TR2b. In the Y-direction, the distance L2 between the end part 10 of the closest trench TR1 closest to the extending part TR2a and the extending part TR2b is longer than the distance L3 between the end part 10 of the other trench TR1 and the extending part TR2b.

A semiconductor device includes a chip having a main surface, a trench resistance structure formed in the main surface, a gate pad that has a resistance value lower than that of the trench resistance structure and that is arranged on the trench resistance structure so as to be electrically connected to the trench resistance structure, and a gate wiring line that has a resistance value lower than that of the trench resistance structure and that is arranged on the trench resistance structure so as to be electrically connected to the gate pad via the trench resistance structure.

An SiC semiconductor device includes a chip that includes an SiC monocrystal and has a main surface, a trench structure that has a side wall and a bottom wall and is formed in the main surface, and a contact region of a first conductivity type that includes a first region formed in a region along the side wall in a surface layer portion of the main surface and a second region formed in a region along the bottom wall inside the chip and having an impurity concentration lower than an impurity concentration of the first region.

A semiconductor device (1A) includes a chip (2) that includes an SiC monocrystal and has a main surface (3), a trench structure (20) that has a first side wall (22A) extending in an a-axis direction of the SiC monocrystal and a second side wall (22B) extending in an m-axis direction of the SiC monocrystal and is formed in the main surface, and a contact region (50) of a first conductivity type that is formed in a region inside the chip along the trench structure at an interval in the a-axis direction from the second side wall.