EE Project3: Metal oxide Semiconductor Field Effect Transistor (MOSFET) Design 1) Modify the mask for LDD nMOS, for 0.13um. View device structures and doping profiles at the end of each major processing steps.

Each module can be considered as a major processing step.To change it to 0.13um, the scale used 0.5856, and the measured Lchan = 0.

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124454um which is close to 0.13um. I got this Lchan measurement from the run table.There are several modules in the recipe as follow:1)      N-MOS2)      Scale module3)      Initial processing         9) Metal14)      Field oxide                  10) nldVg 5)  Channel implant                  11) nldVd 6) Gate oxide                         12) Brk 7) Gate formation 8) Idd, source drain formation  Cutline of the doping profile of the structure. 2.1)Describe the NMOS transistor performance parameters:i) Threshold voltage, Vt  =  The threshold voltage is usually defined as the gate voltage at which the total band bending at the surface is equal to double the difference, ?b = Vth.

In (Na/ni), between the intrinsic Fermi level, Efi, and the Fermi level in the substrate, Ef. At this band bending, the electron concentration at the insulator-semiconductor interface becomes equal to the hole concentration in the bulk. This situation is called inversion or as strong inversion, and the layer of free electrons induced at the surface is called an inversion layer.In other words, the value of VGS at which a sufficient number of mobile electrons accumulate in the channel region to form a conducting channel is called the threshold voltage.Vt = ?MS + 2?F + Qdep/CoxWhere ?MS is the difference between the work functions of the polysilicon gate and the silicon substrate, ?F = (Kt/q) ln(Nsub/ni), q is electron charge, Nsub is the doping concentration of the substrate, Qdep is the charge in the depletion region, and Cox is the gate oxide capacitance per unit area.Linear threshold voltages (Vto and Vts)Vt0 ? Vgs | Ids=0 @gm=max (Vds=0.05V)Saturation threshold voltageVts ? Vgs | Ids =Icrit (Icrit=Ids @Vgs=Vt0)ii) On-state saturation current (Idsat or Ion)Ion ? Ids |Vgs =Vds =1.5Viii)Off-state leakage current (Ioff)Ioff ? Ids | Vgs =0, Vds=1.

5Viv) gm = gm is the parameters that relates id and Vgs in the transistor. In a sense, gm represents the sensitivity of the device: for a high gm, a small change in Vgs results in a large change in Id. gm ?d(Ids)/d(Vgs)           (Vds=1.5V) v) Subthreshold wing: (St) {St ? ?Vgs/ ?Ids (mV/dec) (Vds=1.8V)}   Vto0.3075vVts0.

2063vIon7.76449e-14 AIoff3.896e-10 ASt83.68mV/dec2.2) For the 0.13um nMOS design, from the Run Table,   2.

3)  Observe and familiarize with the device I-V characteristics, such as Ids-Vgs, log(Ids)-Vgs, and Ids-Vds. From the Ids-Vgs curve, the Vt0 is ~0.4v; and Vsat is ~0.3v.  3.

1) Channel Length vs MOS performance (Vt, Ion, Ioff, gm and St)  ParameterLg=1umLg=0.5umLg=0.35umLg=0.25umLg=0.2umLg=0.18umLg=0.13umVt4.





54E-065.22E-065.60E-068.00E-06St (mv/dec)56.1667.5777.06108.

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320.363.2) Obtain technology characterization curves. Vto-log(Lg), Vts-log(Lg), Ion-log(Lg), log(Ioff)-log(Lg) and log(Ioff)-Ion ParameterLg = 0.13L=0.

2L= 0.25Vto, V0.3075v0.3808v0.4096vVts, V0.

20360.27430.3048Ion, A7.

76449e-46.00125e-45.26275e-4Ioff, A3.896e-104.38e-111.

317e-11 The greater concern for short channel effect today is the hot carrier effect. Hot carrier effect can cause threshold voltage shifts, carrier mobility decrease and reduced circuit speed. 4.1) Add a halo-implant (boron) step to the original flow and observe threshold voltage variations at decreasing gate length.

In this step you only need to choose one variable and vary the chosen variable to ge the threshold voltage sensitivity to that variable.The device structure with the halo implant Dose2.5e133.5e134.5e135.5e137e13Lchan (um)0.2863370.3082600.3277450.3453670.366581Vth1.1731.4221.6731.9072.244Observation: 1.When gate length decrease, Vt decrease.By using DOE,  I am able to change the process variables, gate oxidation time and Vt adjustment implant which can change the tox and Ns. Below are the graphs that I obtain from the simulations:i) Vth_Dose-Vth                                                  ii) Oxidation time-VthRSM of the chosen process parameter          RSM of the chosen process parameter(Linear scale)                                                 (Log scale)     From the polynomial models, the R**2 = 0.999449 and the adjusted R**2=0.999385.This shows that the DOE results are pretty good! The equation used in the model is Vth=1.71015870609144 + 0.49249219176034 * [(VTH_DOSE-1.055527e13)/8.81563e12] + 0.0792213592546908 * [(oxidation_time-69.61675)/8.43745]