Electromagnetic interference shielding for image sensor

摘要

An image sensing structure comprises an integral optically transparent conductive layer which provides EMI shielding. The solution is implemented at die level.
A substrate (30) is typically formed from silicon and comprises an active layer (32) which contains a number of doped regions for the collection and manipulation of photogenerated electrons. A layer of metal interconnects (34) is formed on the active layer (32), forming the pixel circuitry and for the transfer of charge from the die to the PCB. Next, a passivation layer (36) is formed. According to one embodiment, an additional optically transparent conductive layer (38) is formed prior to the colour filter array (40). In an alternative embodiment, the optically transparent conductive layer (38) can be formed after the colour filter array (40). The optically transparent conductive layer (38) is preferably formed from indium tin oxide (ITO), and has a thickness chosen to give a reduction of at least 10 dB in EMI emitted by the image sensing structure during operation.