Circuit for and an electronic device including a nonvolatile memory cell and a process of forming the electronic device
View Patent ↗A circuit for a nonvolatile memory cell can include a charge-altering terminal and an output terminal. The circuit can also include a first transistor having a gate electrode that electrically floats and an active region including a current-carrying electrode, wherein the current-carrying electrode is coupled to the output terminal. The circuit can further include a second transistor having a first electrode and a second electrode, wherein the first electrode is coupled to the gate electrode of the first transistor, and the second electrode is coupled to the charge-altering terminal. When changing the state of the memory cell, the second transistor can be active and no significant amount of charge carriers are transferred between the gate electrode of the first transistor and the active region of the first transistor. Other embodiments can include the electronic device itself and a process of forming the electronic device.
1. A circuit for a nonvolatile memory cell comprising:
a charge-altering terminal;
an output terminal configured to provide a signal corresponding to a state of the memory cell when reading the nonvolatile memory cell;
a first transistor including a gate electrode that electrically floats and an active region including a current-carrying electrode, wherein the current-carrying electrode is coupled to the output terminal; and
a second transistor including a first electrode and a second electrode, wherein the first electrode is coupled to the gate electrode of the first transistor, and the second electrode is coupled to the charge-altering terminal,
wherein the circuit is designed such that when changing the state of the memory cell, the second transistor would be active and no significant amount of charge carriers would be transferred between the gate electrode of the first transistor and the active region of the first transistor.
2. The circuit of claim 1 , further comprising a third transistor including a current-carrying electrode, wherein the current-carrying electrode of the first transistor and the current-carrying electrode of the third transistor are conductively coupled to each other.
3. The circuit of claim 2 , wherein the first electrode of the second transistor includes a gate electrode.
4. The circuit of claim 3 , wherein the third transistor includes a gate electrode that is conductively coupled to the gate electrode of the first transistor.
5. The circuit of claim 3 , wherein:
the circuit further comprising a fourth transistor including a first current-carrying electrode, a second current-carrying electrode, and a gate electrode;
the first current-carrying electrode of the fourth transistor is coupled to the current-carrying electrode of the first transistor and the current-carrying electrode of the third transistor;
the second current-carrying electrode of the fourth transistor is coupled to the output terminal; and
the gate electrode of the fourth transistor is coupled to a first pass line.
6. The circuit of claim 5 , further comprising a fifth transistor including a first current-carrying electrode, a second current-carrying electrode, and a gate electrode, wherein:
the first current-carrying electrode of the fifth transistor is coupled to the current-carrying electrode of the first transistor, the current-carrying electrode of the third transistor, and the first current-carrying electrode of the fourth transistor;
the second current-carrying electrode of the fifth transistor is coupled to the second current-carrying electrode of the fourth transistor and the output terminal; and
the gate electrode of the fifth transistor is coupled to a second pass line.
7. The circuit of claim 6 , wherein the first transistor, the second transistor, and the fifth transistor are p-channel transistors, and the third transistor and the fourth transistor are n-channel transistors.
8. The circuit of claim 3 , further comprising a fourth transistor including a first current-carrying electrode, a second current-carrying electrode, and a gate electrode, wherein:
the first current-carrying electrode of the fourth transistor is coupled to the charge altering terminal;
the second current-carrying electrode of the fourth transistor is coupled to the second electrode of the second transistor; and
the gate electrode of the fourth transistor is coupled to a select line.
9. The circuit of claim 8 , wherein the second transistor and the fourth transistor are p-channel transistors.
10. The circuit of claim 2 , wherein the first transistor and the third transistor are n-channel transistors or p-channel transistors.
11. The circuit of claim 2 , wherein:
the first electrode of the second transistor includes a gate electrode, and the second electrode of the second transistor includes a current-carrying electrode; and
the circuit further comprises a fourth transistor including a current-carrying electrode and a gate electrode, wherein:
the current-carrying electrode of the fourth transistor and the current-carrying electrode of the second transistor are coupled to the gate electrode of the first transistor; and
the gate electrode of the fourth transistor is coupled to a select line.
12. The circuit of claim 11 , further comprising:
a fifth transistor including a current-carrying electrode and a gate electrode; and
a sixth transistor including a current-carrying electrode and a gate electrode, wherein:
the current carrying electrode of the first transistor and the current carrying electrode of the third transistor are coupled to the gate electrode of the fifth transistor and the gate electrode of the sixth transistor; and
the current-carrying electrode of the sixth transistor and the current-carrying electrode of the fifth transistor are coupled to each other.
13. The circuit of claim 2 , wherein the first transistor is a p-channel transistor, and the third transistor is an n-channel transistor.
14. An electronic device including a nonvolatile memory cell, wherein the nonvolatile memory cell comprises:
a first active region;
a second active region spaced apart from the first active region;
a floating gate electrode including a first portion and a second portion, wherein:
a first transistor includes the first portion of the floating gate electrode and the first active region;
a second transistor includes the second portion of the floating gate electrode and the second active region; and
no other gate electrode overlies the floating gate electrode;
an output terminal coupled to the first transistor; and
a charge-altering terminal coupled to the second transistor.
15. The electronic device of claim 14 , further comprising a third active region, wherein:
a third transistor includes a third portion of the floating gate electrode and the third active region; and
each of the first and third active regions includes a current-carrying electrode that is coupled to the output terminal.
16. The electronic device of claim 15 , further comprising:
a fourth transistor coupled to the second transistor and the charge-altering terminal; and
a fifth transistor coupled to the first and third transistors and the output terminal.
17. The electronic device of claim 16 , wherein:
the first, second, and fifth transistors are p-channel transistors; and
the third and fourth transistors are n-channel transistors.
18. A process of forming an electronic device including a nonvolatile memory cell, the process comprising:
forming a field isolation region to define a first active region and a second active region;
forming a floating gate electrode including a first portion and a second portion, wherein:
the first portion of the floating gate electrode overlies the first active region;
the second portion of the floating gate electrode overlies the second active region; and
no other gate electrode overlies the floating gate electrode; and
forming source/drain regions within the first active region and the second active region, wherein:
a first transistor includes a first pair of spaced-apart source/drain regions within the first active region and the first portion of the floating gate electrode;
a second transistor includes a second pair of spaced-apart source/drain regions within the second active region and the second portion of the floating gate electrode; and
the memory cell is configured to alter a charge of the floating gate electrode via the second active region, and not the first active region.
19. The process of claim 18 , wherein forming the floating gate comprises:
forming a first layer over the field isolation region, the first active region, and the second active region, wherein the first layer includes a semiconductor material; and
patterning the first layer to form the floating gate electrode and other gate electrodes, wherein all gate electrodes within the memory cell include the first layer.
20. The process of claim 19 , wherein:
patterning the first layer is performed such that the other gate electrodes include a first gate electrode and a second gate electrode;
the first gate electrode is part of a pass transistor coupled to the first transistor; and
the second gate electrode is part of a select transistor coupled to the second transistor.