Method for forming an insulating film

A method for forming an insulating layer, the method comprising:

• providing a substrate having at least two exposed structures made of different materials;
• forming a first insulating layer over the substrate at a first temperature;
• and
• forming a second insulating layer over the first insulating layer at a second temperature, wherein the second insulating layer comprises non-doped silicate glass.

A method for forming an insulating layer comprising the steps of:

• providing a substrate having an exposed oxide structure;
• forming a first insulating layer over the substrate at a first temperature and first thickness;
• and
• forming a second insulating layer over the first insulating layer at a second temperature and a second thickness;
• wherein the first insulating layer and the second insulating layer are formed from substantially same materials, the second temperature is higher than the first temperature, and the second thickness is larger than the first thickness.