AN2386

Case of DEVICE3

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Case of DEVICE3

The device DEVICE3 has similar characteristics of DEVICE1 in terms of tox (470Å), gate

difference between the two devices consists in the channel length (0.8µm) and the source

doping thermal process activation; DEVICE3 perform a form while DEVICE1 an RTA

thermal process.

The only difference on the length channels between the two devices should not have an

effect on the threshold voltage and TVTC. Instead, the different source thermal process

doping activation could bring a variation on the TVTC because the net charge peak

concentration in the channel near the source well is higher in the silicon processed in the

form compared to the RTA one. In fact, when the net charge concentration in the silicon

because new impurity band states are created inside the forbidden silicon band near the

conduction and valence edges.

Figure 27.

Energy band diagram at low and high doping concentration

In order to consider this effect the Slotboom-De Graaf model is used.

Equation 46

concentration (the sum of acceptor and donor doping elements concentration).

The net charge concentration is not easy to establish so, in order to fit the real data, a net

The real data on DEVICE3 using RTA process are shown in the following figures where are

compared to the simulated and the data of the device using the form process.

E

g

∆

b

N

T

10

17

------------

-----

ln





0.5

+

1

2

---

+

ln











=