Techniques for treating sidewalls of patterned structures using angled ion treatment
In one embodiment a method of method of treating a sidewall layer of a patterned feature includes providing the patterned feature as an etched structure comprising one or more layers disposed on a substrate and generally parallel to a plane of the substrate defined by a front surface of the substrate. The sidewall layer comprises material from the one or more etched layers. The method further includes arranging the substrate proximate a sheath modifier that is adjacent a plasma, and providing ions in an ion dose to the substrate by extracting the ions from the plasma through the sheath modifier, the ions impinging upon the substrate at an angle with respect to a perpendicular to the plane of the substrate.
1. A method of treating a sidewall layer of a patterned feature, comprising:
providing the patterned feature as an etched structure comprising one or more layers disposed on a substrate and generally parallel to a plane of the substrate defined by a front surface of the substrate, the sidewall layer comprising material from at least one of the layers;
arranging the substrate proximate a sheath modifier that is adjacent a plasma; and
providing ions in an ion dose to the substrate by extracting the ions from the plasma through the sheath modifier, the ions impinging upon the substrate at an angle with respect to a perpendicular to the plane of the substrate, wherein one or more of the etched layers are metallic, and wherein the sidewall layer is a metallic layer or metal-rich layer.
2. The method of claim 1 , wherein the sidewall layer is disposed at an angle of less than about forty degrees with respect to a perpendicular to the plane of the substrate.
3. The method of claim 1 , wherein the patterned feature has a top layer that is exposed to the ions during the ion dose, wherein the ion dose is effective to etch the sidewall layer at a faster etch rate than the top layer.
4. The method of claim 1 , wherein the ion dose is a first ion dose, the method further comprising:
arranging the substrate at a first rotational angle while providing the ion dose; and
arranging the substrate at a second rotational angle while providing a second ion dose, the ions impinging upon the substrate at an angle with respect to a perpendicular to a plane of the substrate during the second ion dose, wherein the first and second rotational angles each comprises an angle between a line within the plane of the substrate and a plane perpendicular to the plane of the substrate.
5. The method of claim 4 , wherein the substrate includes a two dimensional array of patterned features that define first and second sets of trenches that are oriented along the respective first and second rotational angles.
6. The method of claim 1 , wherein the ion dose is a first ion dose, the method further comprising providing, after the first ion dose, ions in a second ion dose to the substrate at an angle with respect to the perpendicular to the plane of the substrate, the second ion dose effective to generate a passivating layer on sidewalls of the patterned feature.
7. The method of claim 6 , wherein the second ion dose comprises oxygen and/or nitrogen ions having an energy between about 300 eV and 3000 eV.
8. The method of claim 1 , further comprising:
scanning the substrate with respect to the sheath modifier during a time interval of the ion dose;
providing the ion dose as ion pulses defined by an ion duty cycle; and
varying an “on” period of ion pulses during the scanning.
9. The method of claim 1 , wherein the ion dose is a first ion dose and the substrate includes a two dimensional array of patterned features, the method further comprising: providing, after the first ion dose, ions in a second ion dose to the substrate along the perpendicular to the plane of the substrate, the second ion dose effective to remove residue from trench bottom regions between patterned features.
10. The method of claim 9 , further comprising providing, after the second ion dose, ions in a third ion dose to the substrate at an angle with respect to the perpendicular to the plane of the substrate, the third ion dose effective to generate a passivating layer on sidewalls of the patterned features.
11. The method of claim 1 , wherein the patterned feature comprising a magnetic random access memory (MRAM) cell arranged in an array of magnetic random access memory cells, the sidewall layer comprising one or more of Pt, Cr, Mn, Co, Fe, and Ta.
12. A method of treating an array of patterned features on a substrate, comprising:
providing the array of patterned features as a plurality of etched layers generally parallel to a plane of the substrate defined by a front surface of the substrate, each patterned feature bounded by a metallic sidewall layer comprising material from the plurality of etched layers;
arranging the substrate proximate a sheath modifier that is adjacent a plasma; and
providing ions in an ion dose to the substrate by extracting the ions from the plasma through the sheath modifier, the ions impinging upon the substrate at an angle with respect to a perpendicular to the plane of the substrate, wherein the sidewall layer is removed from the array of patterned features.
13. The method of claim 12 , wherein the sidewall layer is disposed at an angle of less than about forty degrees with respect to the perpendicular to the plane of the substrate.
14. The method of claim 12 , wherein the patterned feature having a top layer that is exposed to the ions during the ion dose, wherein the ion dose is effective to etch the sidewall layer at a faster etch rate than the top layer.
15. The method of claim 12 , wherein the ion dose is a first ion dose, the method further comprising:
arranging the substrate at a first rotational angle while providing the first ion dose; arranging the substrate at a second rotational angle while providing a second ion dose, the ions impinging upon the substrate at an angle with respect to a perpendicular to a plane of the substrate during the second ion dose, wherein the first and second rotational angles each comprises an angle between a line within the plane of the substrate and a plane perpendicular to the plane of the substrate.
16. The method of claim 12 , wherein the ion dose is a first ion dose, the method further comprising providing, after the first ion dose, ions in a second ion dose to the substrate at an angle with respect to the perpendicular to the plane of the substrate, the second ion dose effective to generate a passivating layer on sidewalls of the patterned feature.
17. The method of claim 12 , wherein the array of patterned features comprising a magnetic random access memory (MRAM) arranged in an array of magnetic random access memory cells, the sidewall layer comprising one or more of Pt, Cr, Mn, Co, Fe, and Ta.