Bottom thick oxidation growth in high aspect ratio features
The present disclosure generally relate to semiconductor device fabrication, and more particularly, to methods of forming a bottom thick oxide layer in a high aspect ratio semiconductor structures. In certain embodiments, the method includes depositing a non-conformal oxide layer on in a feature on a substrate, performing an oxidation process to thermally grow an oxide layer beneath the deposited non-conformal oxide layer in the feature, and selectively stripping the non-conformal oxide layer to expose the thermally grown oxide layer.
1 . A method for forming an oxide layer, suitable for use in semiconductor manufacturing, the method comprising:
forming a non-conformal oxide layer on a substrate; and then
performing an oxidation process to oxidize the substrate and grow a thermal oxide layer underneath the non-conformal oxide layer; and
selectively removing the non-conformal oxide layer to expose an oxidized portion of the substrate.
2 . The method of claim 1 , wherein the substrate comprises a silicon or a silicon nitride layer, and the silicon or silicon nitride layer includes a high aspect ratio feature having a pair of sidewalls defining an opening opposite of a bottom surface, and wherein the high aspect ratio feature has an aspect ratio of greater than 1:1.
3 . The method of claim 2 , wherein the non-conformal oxide layer is formed on the sidewalls of the high aspect ratio feature with a decreasing thickness between the opening and the bottom surface, wherein one or more portions of the non-conformal oxide layer near the opening is thicker than one or more portions of the non-conformal oxide layer near the bottom surface.
4 . The method of claim 2 , wherein the non-conformal oxide layer comprises aluminum oxide formed with varying thicknesses between about 20 Å and about 50 Å, between the opening and the bottom surface.
5 . The method of claim 2 , wherein forming the non-conformal oxide layer comprises exposing the substrate to one or more precursor gases in an atomic layer deposition (ALD) process, and wherein the aspect ratio is about 10:1 to about 20:1.
6 . The method of claim 1 , wherein selectively removing the oxide layer comprises performing a wet etch process using an etch solution capable of selectively removing the non-conformal oxide layer with minimal or no impact to the thermal oxide layer underneath the non-conformal oxide layer.
7 . The method of claim 6 , wherein the etch solution comprises sulfuric acid, acetic acid, phosphoric acid, nitric acid, piranha solution, or combinations thereof.
8 . A method for forming an oxide layer, suitable for use in semiconductor manufacturing, the method comprising:
forming a non-conformal aluminum oxide layer on a substrate; and then
performing an oxidation process to oxide the substrate and grow a thermal oxide layer underneath the non-conformal aluminum oxide layer; and
selectively removing the non-conformal aluminum oxide layer to expose an oxidized portion of the substrate.
9 . The method of claim 8 , wherein the substrate comprises a silicon or a silicon nitride layer, and the silicon or silicon nitride layer includes a high aspect ratio feature having a pair of sidewalls defining an opening opposite of a bottom surface, and wherein the high aspect ratio feature has an aspect ratio of greater than 1:1.
10 . The method of claim 9 , wherein the non-conformal aluminum oxide layer is formed on the sidewalls of the high aspect ratio feature with a decreasing thickness between the opening and the bottom surface, wherein one or more portions of the non-conformal aluminum oxide layer near the opening is thicker than one or more portions of the non-conformal aluminum oxide layer near the bottom surface.
11 . The method of claim 10 , wherein the non-conformal aluminum oxide layer comprises varying thicknesses between about 20 Å and about 50 Å, between the opening and the bottom surface.
12 . The method of claim 9 , wherein forming the non-conformal aluminum oxide layer comprises exposing the substrate to one or more precursor gases in an atomic layer deposition (ALD) process, and wherein the aspect ratio is about 10:1 to about 20:1.
13 . The method of claim 8 , wherein selectively removing the oxide layer comprises performing a wet etch process using an etch solution capable of selectively removing the non-conformal aluminum oxide layer with minimal or no impact to the thermal oxide layer underneath the non-conformal aluminum oxide layer.
14 . The method of claim 13 , wherein the etch solution comprises sulfuric acid, acetic acid, phosphoric acid, nitric acid, piranha solution, or combinations thereof.
15 . A method for forming an oxide layer, suitable for use in semiconductor manufacturing, the method comprising:
forming a non-conformal aluminum oxide layer on a silicon containing substrate using a deposition process; and then
performing an oxidation process to oxidize the silicon containing substrate and grow a thermal oxide layer underneath the non-conformal aluminum oxide layer; and
performing a wet etching process to selectively remove the non-conformal aluminum oxide layer and expose an oxidized portion of the silicon containing substrate.
16 . The method of claim 15 , wherein the silicon containing substrate comprises silicon or silicon nitride, and the silicon containing substrate includes a high aspect ratio feature having a pair of sidewalls defining an opening opposite of a bottom surface, and wherein the high aspect ratio feature has an aspect ratio of greater than 1:1.
17 . The method of claim 16 , wherein the non-conformal aluminum oxide layer is formed on the sidewalls of the high aspect ratio feature with a decreasing thickness between the opening and the bottom surface, wherein one or more portions of the non-conformal aluminum oxide layer near the opening is thicker than one or more portions of the non-conformal aluminum oxide layer near the bottom surface.
18 . The method of claim 17 , wherein the non-conformal aluminum oxide layer comprises varying thicknesses between about 20 Å and about 50 Å, between the opening and the bottom surface.
19 . The method of claim 15 , wherein forming the non-conformal aluminum oxide layer using the deposition process comprises exposing the substrate to one or more precursor gases in an atomic layer deposition (ALD) process, and wherein the aspect ratio is about 10:1 to about 20:1.
20 . The method of claim 15 , wherein selectively removing the oxide layer comprises performing a wet etch process using an etch solution comprising sulfuric acid, acetic acid, phosphoric acid, nitric acid, piranha solution, or combinations thereof.