Method for patterning a substrate for planarization
Techniques disclosed herein include increasing pattern density for creating high-resolution contact openings, slots, trenches, and other features. A conformal spacer is applied on a bi-layer or tri-layer mandrel (multi-layer) or other relief feature. The conformal spacer thus wraps around the mandrels and is also deposited on an underlying layer. A fill material is deposited to fill gaps or spaces between sidewall spacers. A CMP planarization step then removes substrate stack material down to a material interface of the bi-layer or tri-layer mandrel, with a middle or lower material of the mandrel being a CMP-stop material. This technique essentially cuts off or removes rounded features such as upper portions of sidewall spacers, thereby providing a spacer material with a planar top surface that can be uniformly etched and transferred to underlying layers.
1. A method of patterning a substrate for planarization, the method comprising:
providing a substrate having a relief pattern of structures located on a target layer, structures in the relief pattern of structures comprising at least two layers of material including an upper material layer positioned on a planarization stop material layer, the upper material layer differing from the planarization stop material layer;
depositing a conformal film on exposed surfaces of the target layer and on exposed surfaces of the structures such that sidewall depositions result on vertical surfaces of both the upper material layer and the planarization stop material layer of the structures;
etching the conformal film such that the conformal film is at least removed from portions of target layer surfaces at locations between sidewall depositions of the conformal film;
depositing a fill material that at least partially fills spaces defined between the sidewall depositions of the conformal film; and
planarizing the substrate by removing conformal film material, upper material layer, and fill material above a top surface of the planarization stop material layer such that a planar surface is formed at the top surface of the planarization stop material layer.
2. The method of claim 1 , further comprising etching remaining portions of the conformal film.
3. The method of claim 2 , further comprising transferring a pattern defined by the planarization stop material layer and the fill material into the target layer.
4. The method of claim 3 , wherein transferring the pattern includes executing an anisotropic etch process that etches conformal film material without substantially etching the fill material and the planarization stop material layer such that the fill material and the planarization stop material layer are used as a mask for transferring the pattern into the target layer.
5. The method of claim 1 , wherein depositing the fill material includes depositing sufficient material to cover the top surface of the planarization stop material layer.
6. The method of claim 1 , wherein depositing the conformal film includes depositing the conformal film via atomic layer deposition (ALD).
7. The method of claim 1 , wherein the upper material layer differs from the planarization stop material layer by composition.
8. The method of claim 7 , wherein the upper material layer differs from the planarization stop material layer in that the upper material layer is removed from chemical-mechanical polishing at a rate greater than ten times a removal rate of the planarization stop material layer from chemical-mechanical polishing.
9. The method of claim 1 , further comprising:
removing remaining portions of the fill material and the planarization stop material layer; and
transferring a pattern defined by the conformal film material into the target layer.
10. A method of patterning a substrate for planarization, the method comprising:
providing a substrate having a relief pattern of structures located on a target layer, structures in the relief pattern of structures comprising at least three layers of material including a lower material layer positioned on the target layer, a planarization stop material layer positioned on the lower material layer, and an upper material layer positioned on the planarization stop material layer, the planarization stop material layer differing from the upper material layer and the lower material layer;
depositing a conformal film on exposed surfaces of the target layer and on exposed surfaces of the structures such that sidewall depositions result on vertical surfaces of each of the upper material layer and the planarization stop material layer, and the lower material layer of the structures, material of the conformal film selected such that a particular etch chemistry can etch both the conformal film and material from the lower material layer;
etching the conformal film anisotropically such that the conformal film is removed from target layer surfaces at locations between sidewall depositions of the conformal film;
depositing a fill material that fills spaces defined between the sidewall depositions of the conformal film; and
planarizing the substrate by removing conformal film material, upper material layer, and fill material above a top surface of the planarization stop material layer such that a planar surface is formed.
11. The method of claim 10 , further comprising etching remaining portions of the conformal film.
12. The method of claim 10 , further comprising transferring a pattern defined by the planarization stop material layer and the fill material into the target layer.
13. The method of claim 12 , wherein transferring the pattern includes executing an anisotropic etch process that etches conformal film material without etching the fill material and the planarization stop material layer such that the fill material and the planarization stop material layer are used as a mask for transferring the pattern into the target layer.
14. The method of claim 10 , wherein the upper material layer differs from the planarization stop material layer by composition.
15. The method of claim 14 , wherein the upper material layer differs from the planarization stop material layer in that the upper material layer is removed from chemical-mechanical polishing at a rate greater than ten times a removal rate of the planarization stop material layer from chemical-mechanical polishing.
16. The method of claim 10 , wherein providing the substrate comprises:
depositing the lower material layer on the target layer;
depositing a planarization stop material layer on the lower material layer;
depositing an upper material layer on the planarization stop material layer; and
etching a pattern into the upper material layer, the planarization stop material layer, and the lower material layer thereby creating the relief pattern of structures.
17. A method of patterning a substrate for planarization, the method comprising:
providing a substrate having a relief pattern of structures located on a target layer, structures in the relief pattern of structures comprising at least three layers of material including a lower material layer positioned on the target layer, a planarization stop material layer positioned on the lower material layer, and an upper material layer positioned on the planarization stop material layer, the planarization stop material layer differing from the upper material layer and the lower material layer;
depositing a conformal film on exposed surfaces of the target layer and on exposed surfaces of the structures such that sidewall depositions result on vertical surfaces of each of the upper material layer and the planarization stop material layer, and the lower material layer of the structures, material of the conformal film selected such that a particular etch chemistry can etch both the conformal film and material from the lower material layer;
depositing a fill material that fills spaces defined between the sidewall depositions of the conformal film; and
planarizing the substrate by removing conformal film material, upper material layer, and fill material above a top surface of the planarization stop material layer such that a planar surface is formed.
18. The method of claim 17 , further comprising etching remaining portions of the conformal film.
19. The method of claim 18 , further comprising transferring a pattern defined by the planarization stop material layer and the fill material into the target layer.
20. The method of claim 19 , wherein the upper material layer differs from the planarization stop material layer in that the upper material layer is removed from chemical-mechanical polishing at a rate greater than ten times a removal rate of the planarization stop material layer from chemical-mechanical polishing.