Method of forming an EEPROM device and structure therefor
View Patent ↗In one embodiment, an EEPROM device is formed to include a metal layer having an opening therethrough. The opening overlies a portion of a floating gate of the EEPROM device.
1. A method of forming an EEPROM cell of a semiconductor device comprising:
providing a semiconductor substrate;
forming a channel region of a first MOS transistor on the semiconductor substrate;
forming a floating gate having a bit storage section and also having a gate electrode overlying at least a portion of the channel region;
forming a control gate overlying the bit storage section;
forming a metal layer overlying the control gate; and
forming an opening through the metal layer wherein the opening overlies the at least a portion of the bit storage section and also overlies a first portion of the control gate and wherein the metal layer overlies a second portion of the control gate.
2. The method of claim 1 wherein forming the metal layer overlying the control gate includes forming the metal layer to overlie all of the EEPROM cell that is not underlying the opening.
3. The method of claim 1 wherein forming the opening includes forming the opening to extend past an outer edge of the bit storage section but not beyond an outer edge of the control gate.
4. The method of claim 3 wherein forming the opening to extend past the outer edge of the bit storage section but not beyond the outer edge of the control gate includes forming the opening so that the metal layer overlaps the control gate a distance that is no less than a wavelength of visible light.
5. The method of claim 1 wherein forming the control gate overlying the bit storage section includes forming the control gate to extend a first distance beyond an outer edge of the bit storage section.
6. The method of claim 5 further including forming the first distance to be no less than a wavelength of visible light.
7. The method of claim 1 wherein forming the opening includes forming the opening to overlie at least twenty percent of the surface area of the bit storage section.
8. A method of forming an EEPROM cell of a semiconductor device comprising:
providing a semiconductor substrate;
forming a channel region of a first MOS transistor on the semiconductor substrate;
forming a floating gate having a gate electrode overlying at least a portion of the channel region of the first MOS transistor including forming a bit storage section of the floating to have an outer edge;
forming a control gate overlying the at least a portion of the floating gate; and
forming a metal layer having an opening through the metal layer including forming the metal layer to overlie a first portion of the control gate and forming the opening to overlie a second portion of the control gate and to overlie at least a portion of the bit storage section.
9. The method of claim 8 wherein forming the metal layer having the opening includes forming the opening to overlie the second portion of the control gate with the metal layer overlapping the control gate by at least a wavelength of light.
10. The method of claim 8 wherein forming the control gate overlying at least the portion of the floating gate includes forming the control gate to extend a distance past an outer edge of the bit storage section.
11. The method of claim 10 wherein forming the control gate to extend the distance past the outer edge of the bit storage section includes forming the control gate to extend a distance that is no less than a wavelength of light past an outer edge of the bit storage section.
12. The method of claim 10 wherein forming the control gate to extend the distance includes forming the distance to be no less than a wavelength of visible light or ultraviolet light.
13. The method of claim 8 further including forming a channel region of a second MOS transistor on the semiconductor substrate and forming another gate electrode of the floating gate to overlie at least a portion of the channel region of the second MOS transistor.