Methods and systems for gate dimension control in multi-gate structures for semiconductor devices
View Patent ↗Methods and systems are disclosed for gate dimension control in multi-gate structures for integrated circuit devices. Processing steps for formation of one or more subsequent gate structures are adjusted based upon dimensions determined for one or more previously formed gate structures. In this way, one or more features of the resulting multi-gate structures can be controlled with greater accuracy, and variations between a plurality of multi-gate structures can be reduced. Example multi-gate features and/or dimensions that can be controlled include overall gate length, overlap of gate structures, and/or any other desired features and/or dimensions of the multi-gate structures. Example multi-gate structures include multi-gate NVM (non-volatile memory) cells for NVM systems, such as for example, split-gate NVM cells having select gates (SGs) and control gates (CGs).
1. A method for making an integrated circuit device including a plurality of multi-gate structures, comprising:
forming first gates for a plurality of multi-gate structures for an integrated circuit device, each multi-gate structure to have an overall gate length determined at least in part by a location for an outside edge of the first gate and by a location for an outside edge of a second gate for the multi-gate structure;
determining a location for the outside edge of each of the first gates;
adjusting processing parameters to adjust locations for the outside edges of the second gates based upon the outside edge locations of the first gates and based upon a desired overall gate length for the multi-gate structures; and
forming the second gates using the adjusted processing parameters.
2. The method of claim 1 , wherein at least one hundred or more multi-gate structures are formed, and wherein the overall gate lengths for the plurality of multi-gate structures vary by 10 percent or less.
3. The method of claim 2 , wherein gate lengths for the first gates vary by more than 10 percent.
4. The method of claim 1 , wherein the multi-gate structures comprise multi-gate structures for multi-gate non-volatile memory (NVM) cells.
5. The method of claim 4 , wherein the multi-gate NVM cells comprise split-gate NVM cells, and wherein each of the multi-gate structures comprises a select gate and a control gate.
6. The method of claim 5 , wherein the desired overall gate length comprises a combined gate length for the select gate and the control gate without including any gate overlap.
7. The method of claim 5 , wherein the first gates comprise the control gates for the split-gate NVM cells, and wherein the second gates comprise the select gates for the split-gate NVM cells.
8. The method of claim 5 , wherein the first gates comprise select gates for the split-gate NVM cells, and wherein the second gates comprise control gates for the split-gate NVM cells.
9. The method of claim 8 , wherein the determining step further comprises determining a location for an inside edge of each of the select gates, and wherein the adjusting step further comprises adjusting processing parameters to adjust locations for inside edges of the control gates based upon the inside edge locations for the select gates and based upon a desired overlap length for the inside edges of the control gates over the inside edges of the select gates.
10. The method of claim 5 , further comprising forming a charge storage layer between the select gates and the control gates for the split-gate NVM cells.
11. The method of claim 1 , wherein the adjusting step comprises adjusting processing parameters for a photoresist layer, and wherein the forming the second gates step comprises forming a patterned photoresist layer using the adjusted processing parameters for the photoresist layer, the patterned photoresist layer determining the locations for the outside edges of the second gates.
12. The method of claim 11 , wherein the forming the second gates step further comprises one or more etch processing steps.
13. The method of claim 1 , wherein the multi-gate structures comprise one or more additional gates in addition to the first gates and the second gates.
14. The method of claim 1 , wherein the determining step comprises using an overlay key to determine the outside edge locations for the first gates.