Semiconductor device
View Patent ↗P-type buried regions 104 a and 104 b are formed in an extended drain region 102 formed in a P-type semiconductor substrate 110 . An N-type buried region 113 is formed between the P-type buried regions 104 a and 104 b . An N-type impurity concentration of the N-type buried region 113 along a G–G′ plane is low in the vicinity of boundaries between the N-type buried region 113 and the P-type buried regions 104 a and 104 b and is increased from the boundaries to an inside of the N-type buried region 113.
1. A lateral semiconductor device, comprising:
a first conductivity type semiconductor substrate;
a second conductivity type source region formed in the semiconductor substrate;
a second conductivity type extended drain region formed in the semiconductor substrate;
a gate electrode formed over the semiconductor substrate between the source region and the extended drain region;
a drain region formed in the extended drain region and having a second conductivity type impurity concentration higher than that of the extended drain region;
at least two first conductivity type buried regions formed in the extended drain region at different depths from a surface of the extended drain region; and
a second conductivity type buried region formed between the first conductivity type buried regions,
wherein a second conductivity type impurity concentration at an inside of the second conductivity type buried region is higher than a second conductivity type impurity concentration at boundaries between the first conductivity type buried regions and the second conductivity type buried region.
2. The semiconductor device according to claim 1 , wherein a highest second conductivity type impurity concentration of the second conductivity type buried region formed at a most shallow position from the surface of the extended drain region is higher than a second conductivity type impurity concentration at the surface of the extended drain region.
3. The semiconductor device according to claim 1 , wherein the first conductivity type buried region is formed by ion implantation.
4. The semiconductor device according to claim 1 , wherein the second conductivity type buried region is formed by ion implantation.
5. The semiconductor device according to claim 1 , wherein the second conductivity type buried region is electrically connected to the semiconductor substrate.
6. The semiconductor device according to claim 1 , wherein the first conductivity type buried region and the second conductivity type buried region have substantially the same planar shape.