Memory array with surrounding gate access transistors and capacitors with global and staggered local bit lines

• US 8,101,992 B2
• Filed: 11/19/2010
• Issued: 01/24/2012
• Est. Priority Date: 05/13/2005
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Forbes, Leonard
• Primary Examiner(s): DANG, PHUC T
• Application Number:
  US12/950,088
• Publication Number:
  US 20110121383A1
• Time in Patent Office: 431 Days
• Field of Search: 257/302, 257/401, 257/329, 438/197, 438/238, 438/268, 438/296, 438/587
• US Class Current: 257/329
• CPC Class Codes: G11C 2207/002 Isolation gates, i.e. gates coupling bit lines to the sense amplifier
• CPC Class Codes: G11C 7/18 Bit line organisation; Bit line lay-out
• CPC Class Codes: H01L 29/66477 with an insulated gate, i.e. MISFET
• CPC Class Codes: H10B 12/053 the transistor being at least partially in a trench in the substrate vertical transistor in combination with a capacitor formed in a substrate trench H10B12/0383

Abstract

A memory array with staggered local data/bit lines extending generally in a first direction formed in an upper surface of a substrate and memory cell access transistors extending generally upward and aligned generally atop a corresponding local data/bit line. Selected columns of the memory cell access transistors are sacrificed to define local data/bit access transistors which are interconnected with overlying low resistance global data/bit lines. The global data/bit lines provide selectable low resistance paths between memory cells and sense amplifiers. The sacrificed memory cell access transistors and staggered local data/bit lines provide increased footprints for sense amplifiers to facilitate increased circuit integration.

Claims

1. A memory array comprising:

a semiconductor substrate;

sidewall structures arranged against inner surfaces of openings in sidewall material, wherein the sidewall structures have holes formed therein and wherein the openings are aligned generally with first data/bit lines;

a plurality of vertical extensions within the holes extending generally vertically from a surface of the semiconductor substrate, wherein the vertical extensions are aligned generally with the first data/bit lines;

gate structures formed about the vertical extensions such that the gate structures encompass at least a portion of the vertical extensions; and

second data/bit lines extending across the vertical extensions.

2. The memory array of claim 1, wherein the first data/bit lines comprise a plurality of local data/bit lines in the surface of the substrate.

3. The memory array of claim 1, further comprising plug structures that comprise silicon nitride.

4. The memory array of claim 1, further comprising a plurality of openings in a mask layer on the surface of the substrate such that the openings have a generally square horizontal cross-section.

5. The memory array of claim 1, further comprising at least one local data/bit access line arranged to contact at least one column of corresponding gate structures at least first surfaces thereof so as to define local data/bit access transistors and a plurality of word lines arranged to contact remaining columns of corresponding gate structures at least first surfaces thereof so as to define cell access transistors.

6. The memory array of claim 5, comprising pairs of word lines for corresponding gate structures wherein the pairs are arranged such that a first word line contacts the gate structures at the first surfaces and a second word line contacts the gate structures at opposed second surfaces.

7. The memory array of claim 1, wherein the vertical extensions are doped at lower ends so as to define source regions and at upper regions so as to define drain regions wherein the source regions are in electrical communication with corresponding first data/bit lines so as to define transistor structures having substantially fully depleted characteristics.

8. The memory array of claim 7, wherein the source regions extend substantially fully across the lower regions of the vertical extensions.

9. A memory array comprising:

a semiconductor substrate;

sidewall structures arranged against inner surfaces of openings, wherein the sidewall structures have holes formed therein and wherein the openings are aligned generally with first data/bit lines;

a plurality of vertical extensions within the holes, wherein the vertical extensions are aligned generally with the first data/bit lines;

gate structures about the vertical extensions; and

second data/bit lines extending over the vertical extensions.

10. The memory array of claim 9, wherein the surface of the substrate is doped to define the first data/bit lines.

11. The memory array of claim 9, further comprising plug structures that comprise silicon nitride.

12. The memory array of claim 9, wherein the openings in the masking layer have a generally square horizontal cross-section.

13. The memory array of claim 9, wherein at least one data/bit access line is arranged to contact at least one column of corresponding gate structures at least first surfaces thereof so as to define data/bit access transistors.

14. The memory array of claim 13, further comprising a plurality of word lines arranged to contact columns of corresponding gate structures at least first surfaces thereof so as to define cell access transistors.

15. The memory array of claim 14, further comprising pairs of word lines for corresponding gate structures and arranging the pairs such that a first word line contacts the gate structures at first surfaces and a second word line contacts the gate structures at opposed second surfaces.

16. The memory array of claim 9, further comprising vertical extensions doped at lower ends thereof so as to define source regions and at upper regions thereof so as to define drain regions wherein the source regions are in electrical communication with the corresponding first data/bit lines so as to define transistor structures having substantially fully depleted characteristics.

17. The memory array of claim 16, wherein the source regions extend substantially fully across the lower regions of the vertical extensions.