FinFET with uniform shallow trench isolation recess

A method of making a semiconductor device, the method comprising:

• forming a dense region comprising at least two fins on a substrate, the dense region being arranged adjacent to an isolated region without fins, the at least two fins comprising a first hard mask layer and a second hard mask layer;
• depositing an oxide on the at least two fins of the dense region and on the isolated region of the substrate;
• polishing the oxide, stopping on the second hard mask layer on the at least two fins of the dense region, and removing more oxide in the isolated region, such that polishing forms a non-uniform oxide surface;
• removing the hard mask layer from the at least two fins, exposing the first hard mask layer;
• and
• performing a wet etch process to further recess the oxide in the dense region and the isolated region and remove the first hard mask layer from the at least two fins, such that the oxide in the dense region and the isolated region is substantially uniform in thickness, and to expose tops of the at least two fins.

A method of making a semiconductor device, the method comprising:

• forming a dense region comprising at least two fins on a substrate, the dense region being arranged adjacent to an isolated region without fins within a distance of a pitch of one of the at least two fins, the at least two fins comprising a first hard mask layer and a second hard mask layer;
• depositing an oxide on the at least two fins of the dense region and on the isolated region of the substrate, the oxide filling regions between fins of the at least two fins and extending over the at least two fins;
• removing a portion of the oxide from the dense region and a portion of the oxide from the isolated region, such that more oxide is removed from the isolated region and a non-uniform oxide surface is formed;
• removing the hard mask layer by a selective etch process from the at least two fins, exposing the first hard mask layer and forming recesses in the oxide over the at least two fins;
• and
• performing a wet etch process to further recess the oxide in the dense region and the isolated region and remove the first hard mask layer, such that the oxide in the dense region and the isolated region is substantially uniform in thickness, and to expose tops of the at least two fins.

A method of making a semiconductor device, the method comprising:

• forming a dense region comprising at least two fins on a substrate, the dense region being arranged adjacent to an isolated region without fins, the at least two fins comprising a silicon oxide layer and a silicon nitride layer arranged thereon;
• depositing an oxide on the at least two fins of the dense region and on the isolated region of the substrate;
• polishing the oxide, stopping on the silicon nitride layer on the at least two fins of the dense region, and removing more oxide in the isolated region, such that polishing forms a non-uniform oxide surface;
• removing the hard mask layer from the at least two fins, exposing the silicon oxide layer;
• and
• performing a wet etch process to further recess the oxide in the dense region and the isolated region and remove the silicon oxide layer from the at least two fins, such that the oxide in the dense region and the isolated region is substantially uniform in thickness, and to expose tops of the at least two fins.

A semiconductor device, comprising:

• a dense region comprising at least two fins on a substrate, the at least two fins having a fin pitch;
• a first hard mask layer arranged on the at least two fins, and a second hard mask layer arranged on the first hard mask layer;
• an isolated region without fins arranged on the substrate adjacent to the dense region, the isolated region being free of fins within a distance equal to or greater than the fin pitch of the at least two fins;
• an oxide arranged on and around the at least two fins of the dense region and on the substrate of the isolated region;
• a recess formed in the oxide of the isolated region that has a thickness that is equal to a thickness of the second hard mask layer on the at least two fins.