Method and apparatus for high voltage operation for a high performance semiconductor memory device
View Patent ↗A method and apparatus are provided for high performance, high voltage memory operations on selected memory cells ( 200 ) of a semiconductor memory device ( 100 ). A high voltage generator ( 106 ) during program or erase operations provides a continuous high voltage level ( 702 ) on selected word lines ( 502 ) and maintains a continuous high voltage level supply to a bit line decoder ( 120 ) which sequentially provides the high voltage level ( 706 ) to a first portion of bit lines ( 504 ) and discharges ( 708 ) those bit lines ( 504 ) before providing the high voltage level to a second portion ( 710 ). For additional improvements to program operations, the high voltage generator ( 106 ) decouples high voltages provided to the word lines ( 502 ) and the bit lines ( 504 ) by providing a current flow control device ( 1208 ) therebetween and provides a boosting voltage at a time ( 1104 ) to overcome a voltage level drop ( 1102 ) resulting from a capacitor load associated with selected bit lines ( 504 ) and/or the bit line decoder ( 120 ) precharges ( 1716 ) a second portion of the bit lines ( 504 ) while providing a high voltage level to a first portion to program ( 1706 ) a first portion of memory cells ( 200 ). For improvements to read operations, whether dynamic reference cells ( 2002 ) are blank is determined by providing non-identically regulated high voltage levels from a first voltage source ( 2112 ) to the dynamic reference cells ( 2002 ) and from a second voltage source ( 2104 ) to static reference cells ( 2004 ) and, if the dynamic reference cells ( 2002 ) are not blank, reads selected memory cells ( 200 ) by providing identically regulated high voltage levels to the selected memory cells ( 200 ), the dynamic reference cells ( 2002 ) and the static reference cells ( 2004 ).
1. A method for high voltage programming on selected memory cells of a semiconductor memory device comprising a memory cell array comprising a plurality of memory cells including the selected memory cells, each of said plurality of memory cells accessed by one of a plurality of word lines and one of a plurality of bit lines, the method comprising the steps of:
providing a high voltage level to a first portion of the plurality of bit lines for a predetermined time interval to program a first portion of the selected memory cells;
precharging a second portion of the plurality of bit lines during the predetermined time interval that the high voltage level is provided to the first portion of the plurality of bit lines; and
thereafter providing the high voltage level to the second portion of the plurality of bit lines for the predetermined time interval to program the second portion of the selected memory cells.
2. The method of claim 1 further comprising the step of discharging the first portion of the plurality of bit lines during the predetermined time interval that the high voltage level is provided to the second portion of the plurality of bit lines.
3. The method of claim 1 further comprising the step of providing a continuous high voltage level on selected ones of the plurality of word lines to the selected memory cells for the predetermined time interval to program the first and the second portions of the selected memory cells.
4. The method of claim 1 wherein the step of precharging the second portion of the plurality of bit lines comprises the step of precharging the second portion of the plurality of bit lines to a voltage level less than the high voltage level.
5. The method of claim 4 wherein the step of providing the high voltage level to the second portion of the plurality of bit lines comprises the step of, during the predetermined time interval, further charging the second portion of the plurality of bit lines from the voltage level less than the high voltage level to the high voltage level and thereafter providing the high voltage level to the second portion of the plurality of bit lines.
6. The method of claim 1 wherein the semiconductor memory device comprises a bit line decoder comprising a plurality of data block decoders, each of the plurality of data block decoders coupled to a corresponding one of the plurality of bit lines, and wherein the step of providing the high voltage level to the first portion of the plurality of bit lines for the predetermined time interval comprises the step of providing the high voltage level to a portion of the plurality of data block decoders performing substantially equivalent decoding of the corresponding ones of the plurality of bit lines.
7. A semiconductor memory device comprising:
a memory cell array comprising a plurality of memory cells including selected memory cells for performing high voltage operations thereon;
a plurality of word lines, each of the plurality of word lines coupled to one or more of the plurality of memory cells for access thereof;
a plurality of bit lines, each of the plurality of bit lines coupled to one or more of the plurality of memory cells for access thereof;
a high voltage generator coupled to the plurality of word lines and the plurality of bit lines for generating a high voltage level to the plurality of word lines and the plurality of bit lines; and
a bit line decoder coupled to the high voltage generator and the plurality of bit lines for controlling the provision of high voltage to selected ones of the plurality of bit lines for high voltage operation of selected memory cells, the bit line decoder providing a high voltage level to a first portion of the plurality of bit lines for a predetermined time interval to program a first portion of the selected memory cells, precharging a second portion of the plurality of bit lines during the predetermined time interval that the high voltage level is provided to the first portion of the plurality of bit lines, and thereafter providing the high voltage level to the second portion of the plurality of bit lines for the predetermined time interval to program a second portion of the selected memory cells.
8. The semiconductor memory device of claim 7 wherein the bit line decoder further discharges the first portion of the plurality of bit lines during the predetermined time interval that the high voltage level is provided to the second portion of the plurality of bit lines.
9. The semiconductor memory device of claim 7 further comprising a word line decoder coupled to the high voltage generator and providing a continuous high voltage level on selected ones of the plurality of word lines to the selected memory cells for the predetermined time interval to program the first and the second portions of the selected memory cells.
10. The semiconductor memory device of claim 7 wherein the bit line decoder precharges the second portion of the plurality of bit lines to a voltage level less than the high voltage level.
11. The semiconductor memory device of claim 10 wherein the bit line decoder, during the predetermined time interval, further charges the second portion of the plurality of bit lines from the voltage level less than the high voltage level to the high voltage level and thereafter provides the high voltage level to the second portion of the plurality of bit lines.
12. The semiconductor memory device of claim 7 wherein the bit line decoder comprises a plurality of data block decoders, each of the plurality of data block decoders coupled to a corresponding one of the plurality of bit lines, and wherein the step of providing the high voltage level to the first portion of the plurality of bit lines for the predetermined time interval comprises the step of providing the high voltage level to a portion of the plurality of data block decoders performing substantially equivalent decoding of the corresponding ones of the plurality of bit lines.