Process for controlling performance characteristics of a negative differential resistance (NDR) device
A variety of processes are disclosed for controlling NDR characteristics for an NDR element, such as peak-to-valley ratio (PVR), NDR onset voltage (V NDR ) and related parameters. The processes are based on conventional semiconductor manufacturing operations so that an NDR device can be fabricated using silicon based substrates and along with other types of devices.
1. A method of forming a silicon-based negative differential resistance (NDR) device comprising the steps of:
(a) forming a silicon-based NDR element configured to operate with a negative differential resistance characteristic; and
(b) setting a peak-to-valley ratio (PVR) characteristic of the NDR element at least in part by controlling an impurity species and/or impurity dose introduced into a charge trapping layer associated with said NDR element to match a target charge trap profile;
wherein the silicon-based NDR device is formed using metal oxide semiconductor (MOS) compatible processing operations.
2. The method of claim 1 , wherein said impurity species is Boron.
3. The method of claim 1 , wherein an impurity dose ranging from 1*10 14 /cm 2 to 3*10 14 atoms/cm 2 is used to achieve said target charge trap profile.
4. The method of claim 1 , wherein said target charge trap profile is based on a concentration of greater than about 1*10 19 atoms/cm 3 at a trapping region of said charge trapping layer, and less than about 1*10 18 atoms/cm 3 at a bulk region of said charge trapping layer.
5. The method of claim 1 , wherein said PVR characteristic is set by controlling a process recipe programmed into a semiconductor processing apparatus, such that a first PVR characteristic can be effectuated on a first substrate by a first impurity species and first impurity dose specified in a first process recipe, and a second substantially different PVR characteristic can be effectuated on a second substrate by a second impurity species and second impurity dose specified in a second process recipe.
6. The method of claim 5 , wherein said semiconductor processing apparatus is an ion implanter, a steam anneal chamber, or a thin-film deposition tool.
7. The method of claim 1 , wherein the silicon based NDR element is manufactured on a semiconductor substrate with a first PVR characteristic using a first target charge trap density and a second silicon based NDR element is manufactured on the same semiconductor substrate with a second PVR characteristic using a second target charge trap density.
8. The method of claim 7 , wherein portions of the silicon based NDR element and said second silicon based NDR element are manufactured at substantially the same time using common MOS processing operations.
9. The method of claim 1 , wherein increasing an impurity dose by 50% results in an increase of greater than 100% in said PVR characteristic.
10. The method of claim 1 , wherein an NDR voltage onset point (VNDR) is also set during said manufacture of NDR element.
11. A method of forming a silicon-based negative differential resistance (NDR) device comprising the steps of:
(a) forming a silicon-based NDR element configured to operate with a negative differential resistance characteristic; and
(b) setting a peak-to-valley ratio (PVR) characteristic of the NDR element at least in part by controlling a distribution of charge traps formed in a charge trapping layer associated with said NDR element, including a target location of said charge traps and a target concentration of said charge traps;
wherein the silicon-based NDR device is formed using metal oxide semiconductor (MOS) compatible processing operations.
12. The method of claim 11 , wherein said charge traps are distributed within a target location is a region that is less than about 0.5 nm thick.
13. The method of claim 11 , wherein charge traps are distributed with a target concentration in said target location traps that is at least an order of magnitude greater than in bulk areas of said charge trapping layer.
14. The method of claim 11 , wherein an NDR voltage onset point (VNDR) is also set during said manufacture of silicon-based transistor through controlling said distribution of charge traps.
15. A method of forming a silicon-based negative differential resistance (NDR) device comprising the steps of:
(a) forming a silicon-based NDR element configured to operate with a negative differential resistance characteristic; and
(b) setting a peak-to-valley ratio (PVR) characteristic of the NDR element at least in part by controlling a rapid thermal anneal (RTA) operation during manufacture of said silicon-based NDR element;
wherein the silicon-based NDR device is formed using metal oxide semiconductor (MOS) compatible processing operations.
16. The method of claim 15 , wherein said RTA operation is performed in a programmable anneal chamber, such that a first PVR characteristic is effectuated for silicon based NDR element when a first programmed process recipe is selected, and a second substantially different PVR characteristic is effectuated for said silicon based NDR element when a second programmed process recipe is selected.
17. The method of claim 16 , wherein a PVR value for the NDR element is increased after said RTA operation.
18. The method of claim 15 , wherein said RTA operation takes place at a temperature that exceeds 1000° C. for at least part of said cycle.
19. The method of claim 15 , wherein said RTA operation is used to distribute impurities to a channel interface region to increase a concentration of charge traps at said channel interface region.