Semiconductor device having bonding pad comprising buffer layer

A method of manufacturing a semiconductor device having an electrode layer for insulation and isolation formed in a major surface of a semiconductor substrate through an insulation film, a buffer layer with a periphery surrounded by the electrode layer and being maintained in an electrically floating state, and a bonding pad formed above the buffer layer with an interlayer insulation layer provided therebetween, comprising the steps of:

• sequentially forming a first insulation layer and a conductive layer covering said first insulation layer on the major surface of the semiconductor substrate,
• patterning said conductive layer and said first insulation layer by making a groove in said conductive layer and said first insulation layer bounding a first portion of said conductive layer to simultaneously form said buffer layer in said first portion and said electrode layer in a second portion of said conductive layer outside said first portion,
• covering with a second insulation layer a side surface and an upper surface of said electrode layer and said buffer layer,
• forming an interlayer insulation layer on surfaces of said electrode layer and said buffer layer which are covered with the second insulation layer,
• forming a bonding pad on a surface of said interlayer insulation layer located above said buffer layer.