Method for improving dielectric polishing
View Patent ↗According to one embodiment, a shallow trench isolation (STI) method ( 500 ) may include forming an etch mask layer over both a first and second substrate side ( 504 ). An etch mask layer over a first substrate side ( 506 ) may be patterned to form a STI etch mask, and trenches may be etched into a substrate ( 508 ). A trench dielectric layer can be formed over a first substrate side ( 510 ). An etch mask layer formed over a second substrate side can be etched ( 512 ), reducing and/or eliminating stress that may deform a substrate or otherwise adversely affect STI features. A trench dielectric may then be chemically-mechanically polished (step 514 ).
1. A method, comprising the steps of:
forming a first layer comprising deposited silicon nitride over a first and second side of a substrate:
maintaining the second side of the substrate essentially free of any other overlying layers;
removing at least a portion of the first layer formed over the second side of the substrate; and
forming device features on the first side of the substrate.
2. The method of claim 1 , wherein:
removing at least a portion of the first layer formed over the second side of the substrate includes wet chemically etching with phosphoric acid.
3. The method of claim 1 , wherein:
the layer of silicon nitride has a thickness of less than 3,000 Å.
4. The method of claim 1 , wherein:
removing at least a portion of the first layer formed over the second side of the substrate includes isotropically etching.
5. The method of claim 1 , wherein:
forming device features includes polishing a dielectric layer.
6. The method of claim 5 , wherein:
polishing the dielectric layer includes chemical-mechanical polishing a shallow trench dielectric layer.
7. The method of claim 1 , further including:
removing at least a portion of the first layer formed over the first side of the substrate.
8. The method of claim 7 , wherein:
removing at least a portion of the first layer formed over the first side of the substrate include forming a shallow trench isolation etch mask.
9. The method of claim 1 , further including:
forming a second layer over the first side of the substrate; and
removing at least a portion of the first layer formed over the second side of the substrate includes etching with a high degree of selectivity between the first layer and the second layer.
10. The method of claim 9 , where:
the second layer comprises silicon dioxide.
11. A method, comprising the steps of:
forming a first layer that includes a first part formed over a first substrate side and a second part formed over a second substrate side;
forming a second layer over the first part while maintaining the second substrate side essentially free of any other additional layers;
removing at least a portion of the second part; and
after removing at least the portion of the second part, forming features on the first substrate side.
12. The method of claim 11 , further including;
patterning the first part before forming the second layer.
13. The method of claim 11 , wherein:
removing at least a portion of the second part includes etching essentially all of the second part.
14. The method of claim 13 , further including:
the second layer serves as an etch mask to prevent etching of the first part.
15. A shallow trench isolation (STI) method, comprising the steps of:
forming a trench etch mask layer over a first and second substrate side, the trench etch mask layer including a layer of silicon nitride deposited over the first and second substrate sides;
maintaining the second substrate side essentially free of any additional overlying layers; and
removing at least a portion of the trench etch mask layer that is formed over the second substrate side.
16. The STI method of claim 15 , further including:
patterning the trench etch mask layer formed over the first substrate side and forming a trench dielectric over the first substrate side.
17. The STI method of claim 16 , further including:
etching a substrate to form trenches having a depth of less than 4,000 angstroms with the patterned trench etch mask layer as an etch mask.
18. The STI method of claim 16 , further including:
chemical-mechanical polishing the trench dielectric.