Non-volatile memory and method of manufacturing the same
First Claim
1. A method for manufacturing a non-volatile memory, comprising:
- forming a semiconductor island having tapered side edges on an insulating surface;
forming a first insulating film on the semiconductor island by thermal oxidation of the semiconductor island;
forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island;
forming a second insulating film over the floating gate film; and
forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island.
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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.
26 Citations
36 Claims
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1. A method for manufacturing a non-volatile memory, comprising:
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forming a semiconductor island having tapered side edges on an insulating surface; forming a first insulating film on the semiconductor island by thermal oxidation of the semiconductor island; forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island; forming a second insulating film over the floating gate film; and forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island. - View Dependent Claims (2, 28, 34)
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3. A method for manufacturing a non-volatile memory, comprising:
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forming a semiconductor layer on an insulating surface; forming a photo resist mask having tapered side edges on the semiconductor layer; etching the semiconductor layer to form a semiconductor island having tapered side edges by using the photo resist mask; forming a first insulating film on the semiconductor island by thermal oxidation of the semiconductor island; forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island; forming a second insulating film over the floating gate film; and forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 29, 35)
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11. A method for manufacturing a non-volatile memory, comprising:
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forming a semiconductor island having tapered side edges with two tiers on an insulating surface; forming a first insulating film on the semiconductor island by thermal oxidation of the semiconductor island; forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island; forming a second insulating film over the floating gate film; and forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island. - View Dependent Claims (12, 30, 36)
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13. A method for manufacturing a non-volatile memory, comprising:
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forming a semiconductor island having tapered side edges on an insulating surface; forming a first insulating film on the semiconductor island by CVD; thermally oxidizing a surface of the semiconductor island after the formation of the first insulating film; forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island; forming a second insulating film over the floating gate film; and forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island. - View Dependent Claims (14, 15, 31)
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16. A method for manufacturing a non-volatile memory, comprising:
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forming a semiconductor layer on an insulating surface; forming a photo resist mask having tapered side edges on the semiconductor layer; etching the semiconductor layer to form a semiconductor island having tapered side edges by using the photo resist mask; forming a first insulating film on the semiconductor island by CVD;
thermally oxidizing a surface of the semiconductor island after the formation of the first insulating film;forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island; forming a second insulating film over the floating gate film; and forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 32)
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25. A method for manufacturing a non-volatile memory, comprising:
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forming a semiconductor island having tapered side edges with two tiers on an insulating surface; forming a first insulating film on the semiconductor island by CVD; thermally oxidizing a surface of the semiconductor island after the formation of the first insulating film; forming a floating gate film over a channel forming region of the semiconductor island with the first insulating film interposed therebetween, the floating gate film covering the tapered side edges of the semiconductor island; forming a second insulating film over the floating gate film; and forming a control gate film over the floating gate film with the second insulating film interposed therebetween, the control gate film covering the tapered side edges of the semiconductor island. - View Dependent Claims (26, 27, 33)
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Specification