Semiconductor device with improved planarization properties

A semiconductor device comprising:

• a first conductive layer formed on the surface of a semiconductor substrate,
• a first oxide or nitride layer formed on said semiconductor substrate to cover said first conductive layer,
• a first insulating layer having a first glass transition temperature in a first ambient formed on said first oxide or nitride layer,
• a second oxide or nitride layer formed on said first insulating layer,
• a second conductive layer formed on the surface of said second oxide or nitride layer,
• a third oxide or nitride layer formed on said second oxide or nitride layer to cover the surface of said second conductive layer,
• a second insulating layer formed on said third oxide or nitride layer, and having a second glass transition temperature lower than said first glass transition temperature in said ambient,
• a fourth oxide or nitride layer formed on said second insulating layer, and
• a third conductive layer formed on the surface of said fourth oxide or nitride layer,
• said first insulating layer having a planarized surface and a first film thickness in a region immediately above the first conductive layer, and a second film thickness greater than said first film thickness at other regions,
• said second insulating layer having a planarized surface and a third film thickness at a region immediately above said second conductive layer, and a fourth film thickness greater than said third film thickness at other regions.