Integrated circuits and methods for fabricating integrated circuits having metal gate electrodes

A method for fabricating an integrated circuit, the method comprising:

• forming two first spacers over a semiconductor substrate, wherein the two spacers bound a trench having a lower portion, an upper portion, a boundary between the lower portion and the upper portion, and a top;
• [[and]] wherein the lower portion has a first width, the upper portion has a second width at the boundary greater than the first width, and the upper portion has an increasing width from the boundary to the top, and wherein each first spacer has an upper region corresponding to the upper portion of the trench;
• depositing a first metal in the lower portion of the trench;
• forming a second spacer adjacent the upper region of each first spacer to provide the upper portion of the trench with a reduced width after depositing the first metal in the lower portion of the trench;
• and
• depositing a second metal in the upper portion of the trench.

An integrated circuit comprising:

• a semiconductor substrate;
• first spacers overlying the semiconductor substrate and having base portions with inner surfaces distanced from one another by a first distance and upper portions having inner surfaces distanced from one another by a second distance greater than the first distance;
• second spacers overlying the base portions of the first spacers and adjacent the upper portions of the first spacers;
• and
• a metal gate electrode structure overlying the semiconductor substrate and including a workfunction metal between the base portions of the first spacers and a fill metal overlying the workfunction metal and between the second spacers.