Methods for preparing small features on a substrate
Embodiments of the present disclosure generally relate to methods for forming features having small and large line widths on the same substrate or device. In some embodiments, the methods described and discussed herein can be used to produce optical and photonic devices. These devices, including augmented reality (AR) devices and/or virtual reality (VR) devices, have desired pattern areas with different features and/or line widths to achieve the desired optical performance.
1. A method for forming features on a workpiece, comprising:
positioning the workpiece comprising a film stack disposed on a substrate, wherein the film stack comprises:
a hard mask layer disposed on the substrate;
a planarization layer disposed on the hard mask layer;
a silicon-containing layer disposed on the planarization layer; and
a patterned photoresist layer disposed on the silicon-containing layer, wherein the patterned photoresist layer comprises a first pattern having a first width and a second pattern having a second width less than the first width;
etching the silicon-containing layer to form trenches extending through the silicon-containing layer and to the planarization layer during a first etching process, wherein the trenches are formed on exposed surfaces of the silicon-containing layer within spaces between the first and second patterns of the patterned photoresist layer, wherein a first set of features corresponding to the first pattern and a second set of features corresponding to the second pattern are formed in the silicon-containing layer, and wherein the silicon-containing layer has the first width in the first set of features and the second width in the second set of features after the first etching process;
etching the planarization layer to further extend the trenches to the hard mask layer during a second etching process, wherein the first set of features corresponding to the first pattern and the second set of features corresponding to the second pattern are further formed in the planarization layer during the second etching process, and wherein the planarization layer has the first width in the first set of features and the second width in the second set of features after the second etching process;
etching the hard mask layer to further extend the trenches to the substrate during a third etching process, wherein the first set of features corresponding to the first pattern and the second set of features corresponding to the second pattern are further formed in the hard mask layer during the third etching process, wherein the hard mask layer has the first width in the first set of features and the second width in the second set of features after the third etching process, wherein the planarization layer has a third width in the first set of features and a fourth width in the second set of features after the third etching process, and wherein the third width is less than the first width and the fourth width is less than the second width;
removing the silicon-containing layer from the planarization layer during a fourth etching process or a polishing process;
depositing a silicon oxide layer over the planarization layer and the hard mask layer within the first set of features and the second set of features;
depositing a protective layer over the first set of features while leaving exposed the second set of features;
exposing the second set of features to a fifth etching process to remove the silicon oxide layer from the second set of features and remove a portion of the hard mask layer within the second set of features, wherein the hard mask layer within the second set of features has the fourth width after the fifth etching process; and
exposing the first set of features to a sixth etching process to remove the protective layer from the first set of features, remove the silicon oxide layer from the first set of features, remove a portion of the hard mask layer within the first set of features, and remove the planarization layer within the first set of features and the second set of features, wherein the hard mask layer within the first set of features has the third width after the sixth etching process.
2. The method of claim 1 , wherein the fifth etching process comprises:
exposing the second set of features to a wet clean process to remove the silicon oxide layer; and then
exposing the second set of features to a dry etch process to remove the portion of the hard mask layer within the second set of features.
3. The method of claim 2 , wherein the silicon oxide layer is exposed to a hydrofluoric acid solution during the wet clean process.
4. The method of claim 2 , wherein the portion of the hard mask layer within the second set of features is exposed to a reactive ion etch process, wherein the hard mask layer is exposed to an etchant during a dry clean process, and wherein the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof.
5. The method of claim 1 , wherein the fifth etching process comprises:
exposing the second set of features to a first dry clean process to remove the silicon oxide layer; and then
exposing the second set of features to a second dry etch process to remove the portion of the hard mask layer within the second set of features.
6. The method of claim 5 , wherein the silicon oxide layer is exposed to an etchant during the first dry clean process, and wherein the etchant comprises trifluoromethane, tetrafluoromethane, methane, oxygen (O 2 ), hydrogen (H 2 ), helium, nitrogen (N 2 ), argon, ions thereof, plasmas thereof, or any combination thereof.
7. The method of claim 5 , wherein the portion of the hard mask layer within the second set of features is exposed to a reactive ion etch process, wherein the hard mask layer is exposed to an etchant during a second dry clean process, and wherein the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof.
8. The method of claim 1 , wherein the sixth etching process further comprises:
exposing the protective layer from the first set of features to a reactive ion etch process to remove the protective layer; and then
exposing the silicon oxide layer from the first set of features to a wet clean process to remove the silicon oxide layer; and then
exposing the first set of features to a dry etch process to remove the portion of the hard mask layer within the first set of features.
9. The method of claim 8 , wherein:
the protective layer within the first set of features is exposed to an etchant during the reactive ion etch process;
the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof; and
the silicon oxide layer from the first set of features is exposed to a hydrofluoric acid solution during the wet clean process.
10. The method of claim 8 , wherein the portion of the hard mask layer within the first set of features is exposed to an etchant during the dry etch process, and wherein the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof.
11. The method of claim 1 , wherein:
the silicon oxide layer is conformally deposited by atomic layer deposition by sequentially exposing the workpiece to a silicon precursor and an oxidizing agent;
the silicon precursor comprises bis(tertbutylamino)silane (BTBAS), bis(diethylamino)silane (BDEAS), bis(dimethylamino)silane (BDMAS), or any combination thereof; and
the oxidizing agent comprises oxygen (O 2 ), atomic oxygen, ozone, water, or any combination thereof.
12. A method for forming features on a workpiece, comprising:
positioning the workpiece comprising a first set of features having a first pattern and a second set of features having a second pattern are formed in a silicon-containing layer, wherein each of the first set of features and the second set of features comprises a film stack disposed on a substrate, and wherein the film stack comprises:
a hard mask layer disposed on the substrate;
a planarization layer disposed on the hard mask layer; and
the silicon-containing layer disposed on the planarization layer, wherein:
the hard mask layer and the silicon-containing layer in the first set of features have a first width;
the hard mask layer and the silicon-containing layer in the second set of features have a second width;
the second width is less than the first width;
the planarization layer in the first set of features has a third width;
the planarization layer in the second set of features has a fourth width;
the fourth width is less than the third width;
the third width is less than the first width; and
the fourth width is less than the second width;
removing the silicon-containing layer from the planarization layer;
depositing a silicon oxide layer over the planarization layer and the hard mask layer within the first set of features and the second set of features;
depositing a protective layer over the first set of features while leaving exposed the second set of features;
removing the silicon oxide layer from the second set of features and removing a portion of the hard mask layer within the second set of features, wherein the hard mask layer within the second set of features has the fourth width after removing the portion of the hard mask layer; and
removing the protective layer from the first set of features, removing the silicon oxide layer from the first set of features, removing a portion of the hard mask layer within the first set of features, and removing the planarization layer within the first set of features and the second set of features, wherein the hard mask layer within the first set of features has the third width after removing the portion of the hard mask layer.
13. The method of claim 12 , wherein removing the silicon oxide layer from the second set of features and removing the portion of the hard mask layer within the second set of features further comprises:
exposing the second set of features to a wet clean process to remove the silicon oxide layer; and then
exposing the second set of features to a dry etch process to remove the portion of the hard mask layer within the second set of features.
14. The method of claim 13 , wherein:
the silicon oxide layer is exposed to a hydrofluoric acid solution during the wet clean process;
the portion of the hard mask layer within the second set of features is exposed to a reactive ion etch process, wherein the hard mask layer is exposed to an etchant during the dry clean process;
the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof.
15. The method of claim 12 , wherein removing the silicon oxide layer from the second set of features and removing the portion of the hard mask layer within the second set of features further comprises:
exposing the second set of features to a first dry clean process to remove the silicon oxide layer; and then
exposing the second set of features to a second dry etch process to remove the portion of the hard mask layer within the second set of features.
16. The method of claim 15 , wherein:
the silicon oxide layer is exposed to an etchant during the first dry clean process;
the etchant comprises trifluoromethane, tetrafluoromethane, methane, oxygen (O 2 ), hydrogen (H 2 ), helium, nitrogen (N 2 ), argon, ions thereof, plasmas thereof, or any combination thereof;
the portion of the hard mask layer within the second set of features is exposed to a reactive ion etch process;
the hard mask layer is exposed to an etchant during a second dry clean process; and
the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof.
17. The method of claim 12 , wherein removing the protective layer from the first set of features, removing the silicon oxide layer from the first set of features, removing the portion of the hard mask layer within the first set of features, and removing the planarization layer within the first set of features and the second set of features, further comprises:
exposing the protective layer from the first set of features to a reactive ion etch process to remove the protective layer; and then
exposing the silicon oxide layer from the first set of features to a wet clean process to remove the silicon oxide layer; and then
exposing the first set of features to a dry etch process to remove the portion of the hard mask layer within the first set of features.
18. The method of claim 17 , wherein the protective layer within the first set of features is exposed to an etchant during the reactive ion etch process;
the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof;
the silicon oxide layer from the first set of features is exposed to a hydrofluoric acid solution during the wet clean process;
the portion of the hard mask layer within the first set of features is exposed to an etchant during the dry etch process; and
the etchant comprises oxygen (O 2 ), chlorine (Cl 2 ), methane, helium, nitrogen (N 2 ), ions thereof, plasmas thereof, or any combination thereof.
19. The method of claim 12 , wherein the silicon oxide layer is conformally deposited by atomic layer deposition by sequentially exposing the workpiece to a silicon precursor and an oxidizing agent, and wherein the silicon precursor comprises bis(tertbutylamino)silane (BTBAS), bis(diethylamino)silane (BDEAS), bis(dimethylamino)silane (BDMAS), or any combination thereof and the oxidizing agent comprises oxygen (O 2 ), atomic oxygen, ozone, water, or any combination thereof.
20. A method for forming features on a workpiece, comprising:
positioning the workpiece comprising a film stack disposed on a substrate, wherein the film stack comprises:
a hard mask layer disposed on the substrate;
a planarization layer disposed on the hard mask layer;
a silicon-containing layer disposed on the planarization layer; and
a patterned photoresist layer disposed on the silicon-containing layer, wherein the patterned photoresist layer comprises a first pattern having a first width and a second pattern having a second width less than the first width;
etching the silicon-containing layer to form trenches extending through the silicon-containing layer and to the planarization layer during a first etching process, wherein the trenches are formed on exposed surfaces of the silicon-containing layer within spaces between the first and second patterns of the patterned photoresist layer, wherein a first set of features corresponding to the first pattern and a second set of features corresponding to the second pattern are formed in the silicon-containing layer, and wherein the silicon-containing layer has the first width in the first set of features and the second width in the second set of features after the first etching process;
etching the planarization layer to further extend the trenches to the hard mask layer during a second etching process, wherein the first set of features corresponding to the first pattern and the second set of features corresponding to the second pattern are further formed in the planarization layer during the second etching process, and wherein the planarization layer has the first width in the first set of features and the second width in the second set of features after the second etching process;
etching the hard mask layer to further extend the trenches to the substrate during a third etching process, wherein the first set of features corresponding to the first pattern and the second set of features corresponding to the second pattern are further formed in the hard mask layer during the third etching process, wherein the hard mask layer has the first width in the first set of features and the second width in the second set of features after the third etching process, wherein the planarization layer has a third width in the first set of features and a fourth width in the second set of features after the third etching process, and wherein the third width is less than the first width and the fourth width is less than the second width;
removing the silicon-containing layer from the planarization layer during a fourth etching process or a polishing process;
depositing a silicon oxide layer over the planarization layer and the hard mask layer within the first set of features and the second set of features;
depositing a protective layer over the first set of features while leaving exposed the second set of features, wherein the protective layer comprises a g-line photoresist material, an i-line photoresist material, a photoresist material which develops at a wavelength of 248 nm, a photoresist material which develops at a wavelength of 193 nm, a bottom anti-reflectant coating (BARC) material, or any combination thereof;
exposing the second set of features to a fifth etching process to remove the silicon oxide layer from the second set of features and remove a portion of the hard mask layer within the second set of features, wherein the hard mask layer within the second set of features has the fourth width after the fifth etching process; and
exposing the first set of features to a sixth etching process to remove at least a portion of the hard mask layer within the first set of features, wherein the hard mask layer within the first set of features has the third width after the sixth etching process.