Core removal
Methods, apparatus, and systems are provided herein for processing a substrate. Generally, the processing involves Spacer-on-Spacer (SoS) Self-Aligned Quadruple Patterning (SAQP) techniques. The disclosed techniques provide a novel process flow that reduces defects by ensuring that cores are not removed from the substrate until the substrate is transferred to a deposition chamber used to deposit a second spacer layer. This reduces or eliminates the risk of structural damage to features on the substrate while the substrate is being transferred or cleaned. Such structural damage is common when the cores are removed from the substrate prior to cleaning and transfer.
1 . A method of processing substrates, the method comprising:
a) receiving a substrate comprising:
i. underlying material,
ii. cores positioned on the underlying material, the cores having sidewalls that are vertically oriented, and
iii. first spacer material lining the sidewalls of the cores;
b) removing the cores, thereby forming first spacer features from the first spacer material previously lining the sidewalls of the cores; and
c) depositing a second spacer layer over the first spacer features, wherein (b) and (c) occur in the same reaction chamber, and wherein the substrate is not removed from the reaction chamber between (b) and (c),
wherein the cores comprise carbon, and
wherein the carbon of the cores has a post-deposition blanket stress of about 50 MPa or less, and has a Young's modulus of about 30 GPa or greater.
2 . The method of claim 1 , further comprising cleaning the substrate to remove unwanted material therefrom, wherein the substrate is cleaned in a wet cleaning operation prior to (b).
3 . The method of claim 1 , further comprising depositing a first spacer layer over the cores, the first spacer layer comprising the first spacer material, and etching back the first spacer layer to remove the first spacer material from horizontal surfaces while leaving the first spacer material on the sidewalls of the cores.
4 . The method of claim 1 , further comprising performing metrology to determine a time at which the cores are removed during (b).
5 . The method of claim 4 , wherein performing metrology comprises performing optical emission spectroscopy.
6 . The method of claim 5 , wherein performing optical emission spectroscopy comprises monitoring a signal associated with the presence of carbon dioxide in the reaction chamber.
7 . The method of claim 4 , wherein performing metrology comprises performing laser interferometry.
8 . The method of claim 1 , further comprising performing scatterometry after (b) and before (c) to measure a width of one or more of the first spacer features.
9 . The method of claim 1 , wherein removing the cores comprises exposing the substrate to an oxygen-containing plasma to ash away the cores.
10 . A method of processing substrates, the method comprising:
a) receiving a substrate comprising:
i. underlying material,
ii. cores positioned on the underlying material, the cores having sidewalls that are vertically oriented,
iii. first spacer material lining the sidewalls of the cores,
iv. a planarizing layer positioned over the cores and first spacer material, a top portion of the planarizing layer being substantially planar,
v. a mask layer positioned over the planarizing layer,
vi. an opening defined in the mask layer and the planarizing layer, the opening positioned above the first spacer material lining one of the sidewalls of one of the cores;
b) removing the first spacer material at a location corresponding to the opening;
c) removing the mask layer;
d) removing the cores and the planarizing layer, thereby forming first spacer features from remaining first spacer material that was not removed in (b), wherein no first spacer feature is formed at the location corresponding to the opening; and
e) depositing a second spacer layer over the first spacer features, wherein (d) and (e) occur in the same reaction chamber, and wherein the substrate is not removed from the reaction chamber between (d) and (e).
11 . The method of claim 10 , wherein the cores and the planarizing layer are removed simultaneously.
12 . The method of claim 10 , wherein removing the cores and the planarizing layer comprises exposing the substrate to an oxygen-containing plasma to ash away the cores and the planarizing layer.
13 . The method of claim 10 , further comprising performing metrology to determine a time at which the cores and/or planarizing layer are removed in (d).
14 . The method of claim 10 , further comprising performing scatterometry after (d) and before (e) to measure a width of one or more of the first spacer features.
15 . A method of processing substrates, the method comprising:
a) receiving a substrate comprising:
i. underlying material,
ii. cores positioned on the underlying material, the cores having sidewalls that are vertically oriented,
iii. first spacer material lining the sidewalls of the cores, and
iv. a planarizing layer positioned over the underlying material, the cores, and the first spacer material, wherein the planarizing layer is patterned to form exposed regions and protected regions;
b) trimming the first spacer material to reduce a thickness of the first spacer material in the exposed regions while the first spacer material in the protected regions remains untrimmed;
c) removing the planarizing layer and the cores, thereby forming first spacer features from the first spacer material, wherein the first spacer features have non-uniform critical dimensions; and
d) forming a second spacer layer over the first spacer features,
wherein (c) and (d) occur in the same reaction chamber, and wherein the substrate is not removed from the reaction chamber between (c) and (d).
16 . The method of claim 15 , further comprising etching back the second spacer layer such that the second spacer layer is removed in areas between adjacent first spacer features.
17 . The method of claim 16 , further comprising removing the first spacer features, thereby forming second spacer features from the second spacer layer, wherein a distance between adjacent second spacer features is non-uniform due to the non-uniform critical dimensions of the first spacer features.
18 . The method of claim 15 , wherein the planarizing layer and the cores are removed simultaneously.
19 . The method of claim 18 , wherein removing the cores and the planarizing layer comprises exposing the substrate to an oxygen-containing plasma to ash away the cores and the planarizing layer.