Efficient pitch multiplication process
Pitch multiplied and non-pitch multiplied features of an integrated circuit, e.g., features in the array, interface and periphery areas of the integrated circuit, are formed by processing a substrate through a mask. The mask is formed by patterning a photoresist layer which simultaneously defines mask elements corresponding to features in the array, interface and periphery areas of the integrated circuit. The pattern is transferred to an amorphous carbon layer. Sidewall spacers are formed on the sidewalls of the patterned amorphous carbon layer. A layer of protective material is deposited and then patterned to expose mask elements in the array region and in selected parts of the interface or periphery areas. Amorphous carbon in the array region or other exposed parts is removed, thereby leaving a pattern including free-standing, pitch multiplied spacers in the array region. The protective material is removed, leaving a pattern of pitch multiplied spacers in the array region and non-pitch multiplied mask elements in the interface and periphery areas. The pattern is transferred to a hard mask layer, through which an underlying substrate is etched.
1. A partially fabricated integrated circuit, comprising:
a plurality of pairs of free-standing spacers disposed over an array region of the partially fabricated integrated circuit; and
an other plurality of pairs of spacers on a same level as the plurality of pairs of spacers, wherein spacers of the other pairs of spacers are disposed on sidewalls of a mandrels selectively etchable relative to the other pairs of spacers,
wherein one or more openings are provided in the mandrels.
2. The partially fabricated integrated circuit of claim 1 , wherein the one or more openings extend completely through the mandrel.
3. The partially fabricated integrated circuit of claim 2 , wherein the one or more openings expose an underlying hardmask layer.
4. The partially fabricated integrated circuit of claim 1 , wherein exposed sidewalls of the one or more openings are formed by material forming the mandrels.
5. The partially fabricated integrated circuit of claim 4 , wherein the mandrel is formed of amorphous carbon.
6. The partially fabricated integrated circuit of claim 1 , wherein the one or more openings are disposed in one or more periphery areas of the partially fabricated integrated circuit.
7. The partially fabricated integrated circuit of claim 1 , wherein the free-standing spacers have a separation of less than about 100 nm and the other pairs of spacers have a separation of greater than about 100 nm.
8. The partially fabricated integrated circuit of claim 1 , wherein the pairs of free-standing spacers extend in spaced, generally parallel relation to one another at least between first and second spaced planes extending perpendicular to the pairs of free-standing spacers.
9. The partially fabricated integrated circuit of claim 8 , wherein the other pairs of spacers extend in spaced, generally parallel relation to one another at least between first and second spaced planes extending perpendicular to the other pairs of spacers.