Non-volatile memory and method of manufacturing the same
First Claim
1. A non-volatile memory having a plurality of memory transistors, each of the memory transistors including:
- a semiconductor having first and second impurity regions and a channel forming region;
a first insulating film that is in contact with the semiconductor;
a first gate that is in contact with the first insulating film;
a second insulating film that is in contact with the first gate; and
a second gate that is in contact with the second insulating film, wherein, at least a region of side ends of the semiconductor that overlaps with the first insulating film and with the first gate is tapered.
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Accused Products
Abstract
A non-volatile memory in which a leak current from an electric charge accumulating layer to an active layer is reduced and a method of manufacturing the non-volatile memory are provided. In a non-volatile memory made from a semiconductor thin film that is formed on a substrate (101) having an insulating surface, active layer side ends (110) are tapered. This makes the thickness of a first insulating film (106), which is formed by a thermal oxidization process, at the active layer side ends (110) the same as the thickness of the rest of the first insulating film. Therefore local thinning of the first insulating film does not take place. Moreover, the tapered active layer side ends hardly tolerate electric field concentration at active layer side end corners (111). Accordingly, a leak current from an electric charge accumulating layer (107) to the active layer (105) is reduced to improve the electric charge holding characteristic. As a result, the first insulating film can be further made thin to obtain a high performance non-volatile memory that operates at a low voltage and consumes less power.
56 Citations
26 Claims
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1. A non-volatile memory having a plurality of memory transistors, each of the memory transistors including:
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a semiconductor having first and second impurity regions and a channel forming region;
a first insulating film that is in contact with the semiconductor;
a first gate that is in contact with the first insulating film;
a second insulating film that is in contact with the first gate; and
a second gate that is in contact with the second insulating film, wherein, at least a region of side ends of the semiconductor that overlaps with the first insulating film and with the first gate is tapered. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of manufacturing a non-volatile memory, comprising:
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forming a tapered resist on a semiconductor;
using the tapered resist as a mask for anisotropic etching of the semiconductor to taper side ends of the semiconductor;
forming a first insulating film on the semiconductor with its side ends tapered;
forming a first gate that is in contact with the first insulating film;
forming a second insulating film that is in contact with the first gate; and
forming a second gate that is in contact with the second insulating film. - View Dependent Claims (9, 10, 11, 12, 14, 15, 17, 18, 20)
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13. A non-volatile memory comprising:
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a semiconductor film formed on an insulating surface;
a first insulating film formed on said semiconductor film;
a floating gate formed on said first insulating film;
a second insulating film formed on said floating gate; and
a control gate formed on said second insulating film, wherein side ends of said semiconductor film are tapered.
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16. A non-volatile memory comprising:
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a semiconductor film comprising crystalline silicon formed on an insulating surface;
a first insulating film formed on said semiconductor film;
a floating gate formed on said first insulating film;
a second insulating film formed on said floating gate; and
a control gate formed on said second insulating film, wherein side ends of said semiconductor film are tapered.
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19. A non-volatile memory comprising:
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a semiconductor film formed on an insulating surface;
a first insulating film formed on said semiconductor film;
a floating gate formed on said first insulating film;
a second insulating film formed on said floating gate; and
a control gate formed on said second insulating film, wherein side ends of said semiconductor film are tapered at an angle of 20 to 70°
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21. A non-volatile memory comprising:
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a semiconductor film formed on an insulating surface;
a first insulating film formed on said semiconductor film;
a floating gate formed on said first insulating film;
a second insulating film formed on said floating gate; and
a control gate formed on said second insulating film, wherein at least one side end of said semiconductor film has at least two tapered portions. - View Dependent Claims (22, 24, 26)
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23. A non-volatile memory comprising:
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a semiconductor film formed on an insulating surface;
a first insulating film formed on said semiconductor film;
a floating gate formed on said first insulating film;
a second insulating film formed on said floating gate; and
a control gate formed on said second insulating film, wherein at least one side end of said semiconductor film has at least two tapered portions.
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25. A non-volatile memory comprising:
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a semiconductor film formed on an insulating surface;
a first insulating film formed on said semiconductor film;
a floating gate formed on said first insulating film;
a second insulating film formed on said floating gate; and
a control gate formed on said second insulating film, wherein at least one side end of said semiconductor film has a first tapered portion and a second tapered portion thereon, wherein an angle of said second tapered portion is larger than that of said second tapered portion.
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Specification