A compact MEMS motion sensor device is provided, including a 
CMOS substrate layer, with plural anchor posts having an isolation 
oxide layer surrounding a conductive layer. On one side of 
CMOS substrate layer, the device further includes a 
field oxide (FOX) layer, a first set and a second set of 
implant doped 
silicon areas, a first polysilicon layer, an 
oxide layer embedded with plural 
metal layers interleaved with via hole 
layers, a 
Nitride deposition layer, an under bump 
metal (UBM) layer and a plurality of solder spheres. On the other side of 
CMOS substrate layer, the present invention further includes a backside interconnect isolation 
oxide layer, a first MEMS bonding layer, a first 
metal compound layer, a second MEMS bonding layer, a MEMS layer, a first MEMS 
eutectic bonding layer, a second metal compound layer, a second MEMS 
eutectic bonding layer, and a MEMS cap layer.