SiC-SOI DEVICE AND MANUFACTURING METHOD THEREOF

A SiC-SOI device, comprising:

• a first substrate;
• and
• a SiC substrate bonded to the first substrate through an insulating film,
• wherein a device region, and a surrounding region surrounding the device region are formed in the SiC substrate, and
• the device region includes:
• a drift region of a first conductivity type;
• a first trench that continuously or intermittently surrounds the drift region and that does not penetrate the SiC substrate;
• a first diffusion region of the first conductivity type that is formed on each side surface of the first trench, the first diffusion region being higher in impurity concentration than the drift region;
• a second diffusion region of the first conductivity type that is formed under the drift region and is in contact with the first diffusion region, the second diffusion region being higher in impurity concentration than the drift region;
• a third diffusion region of a second conductivity type that is formed in a surface layer of the drift region;
• a buried region of the second conductivity type that is formed deeper than the third diffusion region in the drift region;
• and
• a plurality of second thin insulating films formed parallel to a surface of the drift region at regular spacings of 0.4 μm or less and as deep as the buried region in the drift region.

A method for manufacturing a SiC-SOI device, the method comprising:

• (a) forming a plurality of first thin insulating films parallel to and in proximity to a surface of a drift region at regular spacings of 0.4 μm or less, the drift region being included in a SiC substrate of a first conductivity type;
• (b) bonding a rear surface of the SiC substrate of the first conductivity type to a Si substrate through an insulating layer;
• (c) forming a first trench to continuously or intermittently surround the drift region in the SiC substrate, the first trench not penetrating the SiC substrate and being formed from a surface of the SiC substrate;
• (d) forming a first diffusion region of the first conductivity type on each side surface of the first trench, the first diffusion region being higher in impurity concentration than the drift region;
• (e) forming a second trench to surround the first trench, the second trench penetrating the SiC substrate;
• and
• (f) forming an isolated insulating film region on each side surface of the second trench.

A method for manufacturing a SiC-SOI device, the method comprising:

• (a) forming a third diffusion region of a second conductivity type in a surface layer of a drift region included in a SiC substrate of a first conductivity type;
• (b) forming a buried region deeper than the third diffusion region in the drift region, the buried region being of the second conductivity type;
• (c) forming a plurality of second thin insulating films parallel to a surface of the drift region at regular spacings of 0.4 μm or less and as deep as the buried region in the drift region;
• (d) bonding a rear surface of the SiC substrate of the first conductivity type to a Si substrate through an insulating layer;
• (e) forming a first trench to continuously or intermittently surround the drift region in the SiC substrate, the first trench not penetrating the SiC substrate and being formed from a surface of the SiC substrate;
• (f) forming a first diffusion region of the first conductivity type on each side surface of the first trench, the first diffusion region being higher in impurity concentration than the drift region;
• (g) forming a second trench to surround the first trench, the second trench penetrating the SiC substrate;
• and
• (h) forming an isolated insulating film region on each side surface of the second trench.