AN1506 - APPLICATION NOTE

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Figure 1. Cell-based and strip-based structures of two Power MOSFETs

In the strip-based layout process an intermediate dielectric layer is obtained after growing the gate oxide

and depositing the poly silicon. In such a sandwich structure parallel strips are opened through an

appropriate photo masking process. After implanting the body, the source regions are created by using a

sort of small rectangle (patches) masking. The longer sides of the patches are perpendicular to the strips

in such a way that they do not need to be aligned within the strip but only along their spacing, which

normally is larger than the opening, thus avoiding any alignment problem. The next step is to isolate the

poly silicon along the stripe’ s periphery thanks to the spacer process. Etching the dielectric material

originally deposited and creating “hills”on the sides of the strips achieve this. Finally, Aluminum

deposition is done in order to contact the strips, and the fabrication flow chart is completed.

Figure 2. Cell-based and strip-based structures of two Power MOSFETs showing the key

parameters of the elemental component of the geometry

L

S

L

S

source

body

source

body

c

bt

L

cb

t

n

p

a)

b)

source

body

source

n+

p

n+

p

n+

p-vapox

poly

SiO2