Fin isolation structure for FinFET and method of forming the same

A semiconductor device structure, comprising:

• a substrate having a first fin, a second fin, and a third fin protruding from the substrate, wherein the second fin is adjacent to and spaced apart from the first fin along a first direction and the third fin adjacent to and spaced apart from the first fin along a second direction that is different from the first direction;
• a first insulating layer having a first portion formed between the first fin and the second fin and a second portion formed between the first fin and the third fin;
• a second insulating layer having a first portion formed in the first portion of the first insulating layer and a second portion formed in the second portion of the first insulating layer;
• and
• a capping structure formed in the first insulating layer to cover the first and second portions of the second insulating layer.

A method of forming a semiconductor device structure, comprising:

• patterning a substrate to define first and second fins separating from each other by a first opening;
• cutting the first and second fins to form a second opening that divides each of the first and second fins into two parts;
• conformally forming a first insulating layer in the first and second openings;
• forming a second insulating layer in the first and second openings opening to cover the first insulating layer;
• recessing the second insulating layer, so that a portion of the first insulating layer protrudes above a top of the second insulating layer;
• and
• forming a dual capping structure in the first and second openings to cover the top of the second insulating layer.