Apparatus and methods including source gates
Apparatus and methods are disclosed, such as an apparatus that includes a string of charge storage devices associated with a pillar (e.g., of semiconductor material), a source gate device, and a source select device coupled between the source gate device and the string. Additional apparatus and methods are described.
1. An apparatus comprising:
a first string of charge storage devices associated with a pillar comprising semiconductor material;
a second string of charge storage devices associated with a pillar comprising semiconductor material;
a first source select device having a gate, the first source select device coupled to the first string of charge storage devices;
a second source select device having a gate, the second source select device coupled to the second string of charge storage devices, wherein the gates of the first and second source select devices are separated from one another;
a first source gate device having a gate, the first source gate device coupled between the first source select device and a source; and
a second source gate device having a gate, the second source gate device coupled between the second source select device and the source, wherein the gates of the first and second source gate devices are coupled to one another to be controlled in common.
2. The apparatus of claim 1 , comprising:
a third string of charge storage devices associated with a pillar comprising semiconductor material;
a fourth string of charge storage devices associated with a pillar comprising semiconductor material;
a third source select device having a gate, the third source select device coupled to the third string of charge storage devices;
a fourth source select device having a gate, the fourth source select device coupled to the fourth string of charge storage devices, wherein the gates of the third and fourth source select devices are separated from each other;
a third source gate device having a gate, the third source gate device coupled between the third source select device and the source; and
a fourth source gate device having a gate, the fourth source gate device coupled between the fourth source select device and the source; and
wherein the gates of the first, second, third, and fourth source gate devices are coupled to one another to be controlled in common.
3. The apparatus of claim 2 , wherein:
gates of the first and third source select devices are coupled to each other to be controlled in common; and
gates of the second and fourth source select devices are coupled to each other to be controlled in common.
4. The apparatus of claim 3 , further comprising:
a first drain select device having a gate, the first drain select device coupled to the first string of charge storage device;
a second drain select device having a gate, the second drain select device coupled to the second string of charge storage devices;
a third drain select device having a gate, the third drain select device coupled to the third string of charge storage devices; and
a fourth drain select device having a gate, the fourth drain select device coupled to the fourth string of charge storage devices:
wherein gates of the first and second drain select devices are separated from each other,
wherein gates of the first and third drain select devices are coupled to each other to be controlled in common, and
wherein gates of the second and fourth drain select devices are coupled to each other to be controlled in common.
5. The apparatus of claim 1 , wherein the first string of the charge storage devices comprises a floating gate transistor.
6. The apparatus of claim 1 , wherein the second string of the charge storage devices comprises a charge trap transistor.
7. The apparatus of claim 1 , wherein the pillar extends from a data line to a well in a substrate.
8. The apparatus of claim 1 , wherein a distance between two gates of the charge storage devices associated with a pillar is shorter than a distance between the gate of the first source select device and the gate of the first source gate device.
9. The apparatus of claim 1 , comprising:
a first block of memory cells comprising,
the first string of charge storage devices,
the second string of charge storage devices,
the first source select device,
the second source select device,
the first source gate device, and
the second source gate device.
10. The apparatus of claim 9 , comprising:
a second block of memory cells, comprising,
a third string of charge storage devices associated with a pillar comprising semiconductor material;
a fourth string of charge storage devices associated with a pillar comprising semiconductor material;
a third source select device having a gate, the third source select device coupled to the third string of charge storage devices;
a fourth source select device having a gate, the fourth source select device coupled to the fourth string of charge storage devices, wherein the gates of the third and fourth source select devices are separated from the gates of the first and second source select devices;
a third source gate device having a gate, the third source gate device coupled between the third source select device and a second source; and
a fourth source gate device having a gate, the fourth source gate device coupled between the fourth source select device and the source, wherein the gates of the first, second, third and fourth source gate devices are coupled to each other to be controlled in common.
11. An apparatus, comprising:
multiple strings comprising charge storage devices;
a first unit of source select devices respectively coupled to strings of a first group of strings of the multiple strings to control conduction between the strings of the first group and a source;
a second unit of source select devices respectively coupled to strings of a second group of strings of the multiple strings to control conduction between the strings of the second group and the source, the first group of strings being different from the second group of strings; and
a first unit of source gate devices, each respectively coupled in series with a source select device of the first and second units of source select devices, to control conduction between the strings of the first and second groups of strings and the source.
12. The apparatus of claim 11 , comprising
a first unit of drain select devices, each coupled to a respective string of the first group of strings, to control conduction between the string and a first data line region; and
a second unit of drain select devices, each coupled to a respective string of the second group of strings, to control conduction between the string and a second data line region.
13. The apparatus of claim 11 , wherein the devices of the third unit of source gate devices are coupled to strings in a block.
14. The apparatus of claim 13 , wherein the first unit of source select devices is coupled to strings of a first sub-block and the second unit of source select devices is coupled to strings of a second sub-block.
15. The apparatus of claim 11 , wherein a distance between two gates of charge storage devices associated with one string is shorter than a distance between a gate of one source select device associated with the first unit of source select devices and a gate of one source gate device associated with the third unit of source gate devices.
16. The apparatus of claim 11 , wherein the charge storage devices comprise floating gate transistors.
17. The apparatus of claim 11 , wherein the charge storage devices comprise charge trap transistors.
18. An apparatus comprising:
a memory unit including:
multiple strings of charge storage devices connected by a channel, strings arranged in multiple rows,
each string associated with a pillar comprising semiconductor material; and
each string in a row including,
a source gate device coupled to a source and configured to control conduction between the channel of charge storage devices in the string and the source, wherein a gate of the source gate device is coupled to the gate of another source gate device in the same row of the multiple rows in the memory unit, and also to the gate of a source gate device in another row of the multiple rows in the memory unit; and
a source select device coupled between the channel of charge storage devices and the source gate device, the source select device configured to control conduction between the channel and the source.
19. The apparatus of claim 18 , wherein the source select device has a gate, and wherein the gate of the source select device is coupled to the gate of another source select device of another string.
20. The apparatus of claim 18 , wherein the gates of all source gate devices in a memory block are coupled in common with one another.