Semiconductor device including dual damascene structure and method for fabricating the same

A method for forming a semiconductor device structure, comprising:

• forming an etch stop layer over a first metal layer and a second metal layer;
• forming a dielectric layer over the etch stop layer;
• forming a hard mask layer over the dielectric layer, wherein the hard mask layer comprising tungsten carbide;
• forming trenches in the hard mask layer, a portion of the dielectric layer being exposed by the trenches;
• forming a patterned photoresist layer over the hard mask layer and the portion of the dielectric layer exposed by the trenches;
• etching through the dielectric layer by performing a dry etching process to form first trenches and first recesses in the dielectric layer by using the patterned photoresist layer as a first etch mask;
• etching through the etch stop layer by performing a wet etching process to form second trenches and vias by using the hard mask layer as a second etch mask;
• and
• filling a conductive material into the vias and the second trenches to form a first damascene structure and a second damascene structure, the first damascene structure comprising a first via portion formed in one of the vias and a first trench portion formed in one of the second trenches, and a center of the first via portion being laterally offset from a center of the first trench portion, the second damascene structure comprising a second via portion formed in another one of the vias and a second trench portion formed in another one of the second trenches, and a center of the second via portion being laterally offset from a center of the second trench portion,
• wherein the first damascene structure and the second damascene structure have a first dimension in a first direction, the first damascene structure and the second damascene structure have a second dimension in a second direction, the first damascene structure and the second damascene structure are spaced apart from each other by a spacing in the first direction, and the first metal layer and the second metal layer have a third dimension in the first direction, and wherein the second dimension is less than the first dimension, and a ratio of the spacing to the third dimension ranges from about 0.84 to about 1.07.

A method for forming a semiconductor device, comprising:

• forming a first metal layer and a second metal layer embedded in a first dielectric layer;
• forming an etch stop layer over the first metal layer, the second metal layer and the first dielectric layer;
• forming a second dielectric layer over the etch stop layer;
• forming a dielectric stack on the second dielectric layer;
• forming a first patterned tri-layer photoresist structure on the dielectric stack;
• patterning the dielectric stack by using the first patterned tri-layer photoresist structure as a mask to form trenches in the dielectric stack;
• after the trenches is formed in the dielectric stack, forming a second patterned tri-layer photoresist structure to cover the dielectric stack;
• patterning the second dielectric layer by using the second patterned tri-layer photoresist structure as a mask to form first recesses in the second dielectric layer;
• removing the second patterned tri-layer photoresist structure to expose the dielectric stack;
• removing a portion of the second dielectric layer to expose a portion of the etch stop layer and to form second recesses by using the dielectric stack as a mask;
• performing a wet etching process to remove the portion of the etch stop layer exposed by the second dielectric layer to expose the first metal layer and the second metal layer so as to form a first damascene cavity and a second damascene cavity;
• and
• forming a first damascene structure in the damascene cavity and forming a second damascene structure in the second damascene cavity, the first damascene structure and the second damascene structure having a first dimension in a first direction, the first damascene structure and the second damascene structure having a second dimension in a second direction, the first damascene structure and the second damascene structure being spaced apart from each other by a spacing in the first direction, and the first metal layer and the second metal layer having a third dimension in the first direction, wherein the second dimension is less than the first dimension, and a ratio of the spacing to the third dimension ranges from about 0.84 to about 1.07.