Granted Patent B1

US 7,985,687 · App. 11/186,969 · Granted Jul 26, 2011

Abstract

Claims (68)

1. A method for forming a memory device, comprising:

forming a first mask layer directly over a substrate;

forming a second mask layer directly over the first mask layer;

etching the first mask layer and the second mask layer to form a hard mask over a first portion of the substrate;

etching a second portion of the substrate, that is not covered by the hard mask, to form a trench;

depositing a field oxide material over the first portion and the second portion, including filling the trench with the field oxide material;

planarizing the field oxide material to expose a top surface of the second mask layer;

stripping the second mask layer from the memory device using a first etching technique, where the first etching technique includes a plasma dry etching technique;

stripping the first mask layer from the memory device using a second etching technique, where the second etching technique includes a wet chemical etching technique,

where the second etching technique is different than the first etching technique;

forming at least two charge storage elements over opposite sides of the trench; and

etching the field oxide material to form an inter-gate dielectric region positioned between an adjacent pair of the at least two charge storage elements where etching the field oxide material to form an inter-gate dielectric region, further comprises:

anisotropic dry etching the field oxide material to a particular depth extending below a lower surface of the at least two charge storage elements; and

forming an inter-gate dielectric region on a top surface of the field oxide material.

2. The method of claim 1 , where the wet chemical etching technique includes using phosphoric acid to strip the first mask layer from the memory device.

3. The method of claim 1 , further comprising:

planarizing the field oxide material and the at least two charge storage elements prior to etching the field oxide material.

4. The method of claim 1 , where the plasma dry etching technique includes using at least one fluorinated hydrocarbon gas to strip the second mask layer from the memory device, and

where the fluorinated hydrocarbon gas is selected to have high selectivity to minimize field oxide etching.

5. The method of claim 4 , where the plasma dry etching technique further comprises:

providing oxygen gas at a flow rate ranging from about 0 sccm to about 50 sccm; and

providing trifluoromethane (CHF 3 ) gas at a flow rate ranging from about 10 sccm to about 60 sccm.

6. The method of claim 1 , where the first mask layer includes a dielectric layer and the second mask layer includes an anti-reflective layer.

7. The method of claim 6 , where the dielectric layer includes a nitride layer.

8. The method of claim 6 , where the anti-reflective layer includes a silicon oxynitride layer.

9. The method of claim 6 , where the dielectric layer has a thickness ranging from about 800 Å to about 1700 Å.

10. The method of claim 6 , where the anti-reflective layer has a thickness ranging from about 300 Å to about 700 Å.

11. A method for fabricating a semiconductor device, comprising:

forming a first dielectric layer over a substrate;

forming a second dielectric layer over the first dielectric layer;

forming an anti-reflective dielectric layer over the first dielectric layer;

forming a photoresist layer over the anti-reflective dielectric layer;

patterning the photoresist layer to define mask regions;

etching the anti-reflective dielectric layer and the second dielectric layer to form a hard mask;

etching the substrate and the first dielectric layer to form at least one isolation trench in a portion of the substrate not covered by the hard mask;

depositing an oxide material over the hard mask and the portion of the substrate not covered by the hard mask, including filling the trench with the oxide material;

planarizing the oxide material to expose a top surface of the anti-reflective dielectric layer;

stripping, using a dry etching technique, the anti-reflective dielectric layer from the semiconductor device;

stripping, using a wet etching technique, the second dielectric layer from the semiconductor device;

forming at least one charge storage element over the oxide material and the first dielectric layer;

forming an inter-gate dielectric layer over the at least one charge storage element; and

forming a control gate over at least a portion of the inter-gate dielectric layer.

12. The method of claim 11 , further comprising;

etching the oxide material, where a top surface of the oxide material is at a depth below a lower surface of the at least one charge storage element, and

where forming the inter-gate dielectric layer further includes:

forming the inter-gate dielectric layer over the top surface of the oxide material, where a portion of the inter-gate dielectric layer, over the oxide material, extends below the lower surface of the one charge storage element.

13. The method of claim 11 , where the second dielectric layer includes a nitride layer and the anti-reflective dielectric layer includes a silicon oxynitride layer.

14. The method of claim 13 , where stripping the anti-reflective layer comprises dry plasma etching the anti-reflective layer.

15. The method of claim 13 , where stripping the second dielectric layer comprises wet phosphorous etching the second dielectric layer.

16. A method for fabricating a memory device, comprising:

forming an oxide layer over a substrate;

forming a nitride layer over the oxide layer;

forming an anti-reflective silicon oxynitride layer over the nitride layer;

patterning and etching the anti-reflective silicon oxynitride layer and the nitride layer to form a mask;

etching the oxide layer and the substrate using the mask to form at least one isolation trench;

forming a field oxide material over the substrate, including forming the field oxide material in the at least one isolation trench;

planarizing the field oxide material to expose a top surface of the anti-reflective silicon oxynitride layer;

removing the anti-reflective silicon oxynitride layer using dry plasma etching;

removing the nitride layer using wet phosphoric acid etching;

forming at least one charge storage element over the oxide layer and the field oxide material;

recessing the field oxide material to a predetermined depth using the at least one charge storage element as a mask;

forming an inter-gate dielectric layer over the at least one charge storage element and the recessed field oxide material; and

forming a control gate over the inter-gate dielectric layer.

17. The method of claim 16 , where the nitride layer has a thickness ranging from about 800 Å to about 1700 Å and where the anti-reflective silicon oxynitride layer has a thickness ranging from about 300 Å to about 700 Å.

18. The method of claim 16 , where recessing the field oxide material to the predetermined depth includes:

recessing the field oxide material below a lower surface of the at least one charge storage element, and

where forming the inter-gate dielectric layer includes:

forming the inter-gate dielectric layer over a top surface of the recessed field oxide material, where a portion of the inter-gate dielectric layer, over the recessed field oxide material, is below the lower surface of the at least one charge storage element.

Assignments (10)