Structure and method for preventing silicide contamination during the manufacture of micro-processors with embedded flash memory
View Patent ↗A method is provided in which a monitor cell is made that is substantially identical to the flash memory cells of an embedded memory array. The monitor cell is formed simultaneously with the cells of the memory array, and so in certain critical aspects, is exactly comparable. An aperture is formed that extends through the control gate and intervening dielectric to the floating gate of the monitor cell. To prevent silicide contamination during a subsequent CMP process, a silicide protection layer (SPL), such as a resist protective oxide, is formed over exposed portions of the control gate prior to formation of a silicide contact formed on the floating gate. The SPL is formed simultaneously with existing manufacturing processes to avoid additional process steps.
1. A method, comprising:
defining a plurality of chips on a semiconductor material wafer;
forming, on each of the chips defined on the semiconductor material wafer, a respective one of a plurality of microprocessor devices, each including an embedded memory;
forming a monitor cell on the semiconductor material wafer, including:
forming a floating gate, a control gate and corresponding dielectric layers;
forming an aperture extending through the control gate of the monitor cell and exposing a portion of the floating gate of the monitor cell;
forming a silicide protection layer over a portion of the control gate of the monitor cell exposed by the forming the aperture; and
following the forming the silicide protection layer, forming a silicide contact terminal on the portion of the floating gate of the monitor cell exposed by the forming an aperture.
2. The method of claim 1 wherein the forming a silicide protection layer comprises forming a silicide protection layer simultaneously with performing processing steps associated with forming the plurality of microprocessor devices.
3. The method of claim 1 , comprising, following the forming a silicide contact terminal, performing a chemical-mechanical polish of the semiconductor material wafer, and exposing a portion of the control gate of the monitor cell.
4. The method of claim 3 , comprising, following the performing a chemical-mechanical polish of the semiconductor material wafer:
depositing an interlayer dielectric layer over the semiconductor material wafer;
forming a metal layer on the interlayer dielectric layer; and
forming an electrical connector between an electrical trace of the metal layer and the silicide contact terminal.
5. The method of claim 1 wherein the forming a monitor cell on the semiconductor material wafer comprises forming a monitor cell on a portion of the semiconductor material wafer that is not defined as part of one of the plurality of chips.
6. The method of claim 1 wherein the forming a monitor cell on the semiconductor material wafer comprises forming a monitor cell on each of the chips defined on the semiconductor material wafer.
7. The method of claim 1 wherein the forming a floating gate, a control gate, and corresponding dielectric layers of the monitor cell includes:
forming substantially identical first tunneling dielectric layers of the monitor cell and the memory cells of each embedded memory;
forming substantially identical floating gates of the monitor cell and the memory cells of each embedded memory; and
forming substantially identical control gates of the monitor cell and the memory cells of each embedded memory.
8. The method of claim 1 , wherein the forming a floating gate, a control gate, and corresponding dielectric layers of the monitor cell includes:
forming substantially identical second tunneling dielectric layers of the monitor cell and the memory cells of each embedded memory between the respective floating gate and a corresponding erase gate.
9. The method of claim 1 , wherein the forming a silicide protection layer comprises forming a silicide protection layer simultaneously with performing processing steps associated with forming the plurality of microelectronic devices on the semiconductor material wafer.
10. The method of claim 9 , wherein the forming a silicide protection layer comprises forming a resist protective oxide layer.
11. The method of claim 1 wherein the forming a monitor cell on the semiconductor material wafer comprises forming a monitor cell on a portion of the semiconductor material wafer outside any of the defined plurality of microchips.
12. The method of claim 1 wherein the forming a monitor cell on the semiconductor material wafer comprises forming a monitor cell on a scribe line of the semiconductor material wafer.
13. A method, comprising:
defining a plurality of chips on a semiconductor material wafer;
forming, on each of the plurality of chips defined on the semiconductor material wafer, an embedded memory;
forming a monitor cell on the semiconductor material wafer, including:
forming a floating gate;
exposing a portion of the floating gate by forming an aperture through one or more structures above the floating gate;
forming a silicide protection layer on a sidewall of the aperture; and
forming a silicide contact terminal on the exposed portion of the floating gate.
14. The method of claim 13 , wherein forming the monitor cell includes forming a control gate above the floating gate.
15. The method of claim 14 , wherein the one or more structures includes the control gate.
16. The method of claim 15 , wherein the sidewall of the aperture includes a sidewall of the control gate.
17. The method of claim 16 , wherein the silicide protection layer inhibits formation of silicide on the sidewall of the control gate during formation of the silicide contact terminal on the exposed portion of the floating gate.
18. A method, comprising:
defining a plurality of chips on a semiconductor wafer;
forming, on each of the plurality of chips, a plurality of memory cells on the semiconductor wafer;
forming, on the semiconductor wafer, a monitor cell, including exposing a portion of a floating gate of one of the plurality of memory cells by forming an aperture in a portion of the one of the plurality of memory cells;
forming a silicide protection layer on a sidewall of a structure exposed by forming the aperture; and
forming a silicide contact terminal on the exposed portion of the floating gate.
19. The method of claim 18 , wherein the structure includes a material susceptible to silicide formation.
20. The method of claim 19 , wherein the structure includes a control gate above the floating gate.