Method of using source bias to raise threshold voltages and/or to compact threshold voltages
First Claim
1. A method for increasing the thresttold voltage of at least one of a plurality of floating-gate memory cells in a nonvolatile integrated-circuit memory having a substrate connected to a reference voltage, each said memory cell being of the single-transistor, non-slit-gate type, said method comprising:
- connecting the sources of said plurality of memory cells to a high impedance;
causing currents to flow into the drains of said plurality memory cells; and
placing a voltage on the control gates of said plurality of memory cells, said voltage being positive with respect to said reference voltage.
0 Assignments
0 Petitions
Accused Products
Abstract
The method of this invention allows use of a smaller wordline voltage Vp1 during programming. In addition, the method results in a relatively narrow distribution of threshold voltages Vt when used to flash program an array of memory cells (10). The method of this invention increases compaction gate-current efficiency by reverse biasing the source (11)/substrate (23) junction of the cell being programmed. The reverse biasing is accomplished, for example, by applying a bias voltage to the source (11) or by placing a diode (27), a resistor (29) or other impedance in series with the source (11). The reverse biasing limits the source current (Is) of cell being programmed and of the entire array during flash-programming compaction.
19 Citations
5 Claims
-
1. A method for increasing the thresttold voltage of at least one of a plurality of floating-gate memory cells in a nonvolatile integrated-circuit memory having a substrate connected to a reference voltage, each said memory cell being of the single-transistor, non-slit-gate type, said method comprising:
-
connecting the sources of said plurality of memory cells to a high impedance; causing currents to flow into the drains of said plurality memory cells; and placing a voltage on the control gates of said plurality of memory cells, said voltage being positive with respect to said reference voltage. - View Dependent Claims (2, 3, 4, 5)
-
Specification