Contact structure and method for fabricating the same

A structure, comprising:

• a transistor comprising a gate and a source/drain region, wherein the gate and the source/drain region extend in a first direction;
• an interlayer dielectric layer covering the transistor;
• a source/drain contact structure embedded in the interlayer dielectric layer, wherein the source/drain contact structure electrically connected to the source/drain region, and the source/drain contact structure comprising:
• a lower part electrically connected to the source/drain region;
• an upper part disposed on the lower part, wherein the upper part has a first top width in the first direction, the upper part has a second top width in a second direction different from the first direction, and the second top width of the upper part is greater than the first top width of the upper part;
• and
• an interconnect wiring disposed on the interlayer dielectric layer, wherein the interconnect wiring extends in the second direction, and the interconnect wiring lands on the upper part of the source/drain contact structure.

A method, comprising:

• forming a transistor over a substrate, the transistor comprising a gate and a source/drain region, wherein the gate and the source/drain region extend in a first direction;
• forming an interlayer dielectric layer to cover the transistor;
• forming a contact opening in the interlayer dielectric layer;
• performing an anisotropic etch process to expand a first lateral dimension of an upper portion of the contact opening in the first direction;
• forming a source/drain contact structure in the contact opening, wherein the source/drain contact structure electrically connected to the source/drain region, and the source/drain contact structure comprising:
• a lower part electrically connected to the source/drain region;
• an upper part disposed on the lower part, wherein the upper part has a first top width in the first direction, the upper part has a second top width in a second direction different from the first direction, and the second top width of the upper part is greater than the first top width of the upper part;
• and
• forming an interconnect wiring on the interlayer dielectric layer, wherein the interconnect wiring lands on the upper part of the source/drain contact structure.