Apparatus including cell contact and redistribution layer structure

An apparatus, comprising:

• a first bit line structure and a second bit line structure;
• a cell contact between the first bit line structure and the second bit line structure;
• and
• a redistribution layer (RDL) on the first bit line structure and the cell contact;
• and
• an insulating material between the second bit line structure on one side and the cell contact and RDL on another side, wherein
• the cell contact includes:
• a first contact part on an active region formed in a semiconductor substrate and including polysilicon;
• a second contact part on the first contact part and including cobalt or cobalt silicide;
• a third contact part on the second contact part and including a first conductive material, the third contact part is configured to cover an entire top surface of the second contact part, the insulating material is on the third contact part;
• and
• a fourth contact part on the third contact part under the RDL and including a second conductive material different from the second conductive material.

An apparatus, comprising:

• a cell contact including:
• a polysilicon portion;
• a cobalt portion on the polysilicon portion;
• a titanium portion on the cobalt portion;
• and
• a tungsten portion on the titanium portion, wherein
• the cobalt portion is covered by the titanium portion, and a side part of the titanium portion is lower than a top part of the tungsten portion;
• and
• a nitride portion adjacent to the cell contact, wherein the nitride portion stops at the titanium portion and does not contact the cobalt portion under the titanium portion.