Low thermal budget dielectric for semiconductor devices

A method, comprising:

• forming, on a substrate, first and second channel structures adjacent to each other and with a first opening therebetween;
• depositing a first flowable isolation material in the first opening;
• densifying the deposited first flowable isolation material;
• forming a first epitaxial structure in contact with the first channel structure and a second epitaxial structure in contact with the second channel structure;
• forming an etch stop layer on the first and second epitaxial structures and the densified first flowable isolation material between the first and second epitaxial structures, wherein a second opening forms between the etch stop layer on the first epitaxial structure and the etch stop layer on the second epitaxial structure;
• depositing a second flowable isolation material to fill the second opening, wherein a portion of the second flowable isolation material is below the first and second epitaxial structures;
• and
• densifying the deposited second flowable isolation material.

A method, comprising:

• forming, on a first side of a substrate, first and second channel structures with an opening therebetween;
• depositing a flowable isolation material in the opening:
• densifying the deposited flowable isolation material in the opening below a temperature;
• removing a portion of the densified flowable isolation material in the opening;
• forming an epitaxial structure on the first and second channel structures and above the densified flowable isolation material;
• forming an etch stop layer on the epitaxial structure and the densified flowable isolation material;
• depositing the flowable isolation material on the etch stop layer;
• densifying the deposited flowable isolation material on the etch stop layer below the temperature;
• depositing the flowable isolation material on a second side of the substrate, wherein the second side is opposite to the first side;
• and
• densifying the deposited flowable isolation material on the second side of the substrate below the temperature.