Reading a phase change memory
View Patent ↗A phase change memory cell may be read by driving a current through the cell higher than its threshold current. A voltage derived from the selected column may be utilized to read a selected bit of a phase change memory. The read window or margin may be improved in some embodiments. A refresh cycle may be included at periodic intervals.
1. A method comprising:
maintaining a selected row line at a voltage above ground when reading a phase change memory cell on said selected row line, and
maintaining unselected row lines at a higher voltage than said selected row line when reading the selected row line.
2. The method of claim 1 including reading a cell with a select device.
3. The method of claim 2 including reading a cell with a chalcogenide select device.
4. A method comprising:
forming a phase change memory that maintains a selected row line at a voltage above ground when reading a bit on said selected row line, and that maintains unselected row lines at a higher voltage than said selected row line when reading the selected row line.
5. The method of claim 4 including forming a memory with a cell having a select device.
6. The method of claim 5 including forming a memory for reading a cell with a chalcogenide select device.
7. A phase change memory comprising:
a plurality of chalcogenide cells; and
a circuit to maintain a selected row line at a voltage above ground when reading a bit on said selected row line, and to maintain unselected row lines at a higher voltage than said selected row line when reading the selected row line.
8. The memory of claim 7 including a sense amplifier to read a phase change memory cell on said selected row line.
9. The memory of claim 8 , said sense amplifier to read a cell with a select device.
10. The memory of claim 9 , said sense amplifier to read a cell with a chalcogenide select device.