Method of manufacturing convex shaped thin-film transistor device
The present invention provides a semiconductor device that has a shorter distance between the bit lines and easily achieves higher storage capacity and density, and a method of manufacturing such a semiconductor device. The semiconductor device includes: first bit lines formed on a substrate; an insulating layer that is provided between the first bit lines on the substrate, and has a higher upper face than the first bit lines; channel layers that are provided on both side faces of the insulating layer, and are coupled to the respective first bit lines; and charge storage layers that are provided on the opposite side faces of the channel layers from the side faces on which the insulating layers are formed.
1. A method of manufacturing a semiconductor device, comprising:
forming a plurality of bit lines on a substrate;
forming an insulating layer between the plurality of bit lines, the insulating layer comprising opposing side surfaces and wherein an upper surface of the insulating layer is higher than upper surfaces of the plurality of bit lines;
forming a plurality of channel layers on the opposing side surfaces of the insulating layer;
forming a tunnel oxide film over the plurality of channel layers, the tunnel oxide film comprising top, bottom, and side surfaces, wherein a portion of the tunnel oxide film is disposed over a top surface of the insulating layer;
forming a plurality of charge storage layers on opposite side surfaces of the plurality of channel layers from the side surfaces on which the insulating film is formed; and
forming a top oxide film over the tunnel oxide film and the plurality of charge storage layers, the top oxide film comprising top, bottom, and side surfaces,
wherein the plurality of charge storage layers is provided between the side surfaces of the top oxide film and side surfaces of the tunnel oxide film,
further wherein at least a portion of the bottom surface of the top oxide film is in direct contact with the top surface of the tunnel oxide film.
2. The method as claimed in claim 1 , further comprising
forming a groove at a portion of the substrate, the portion being located between the plurality of bit lines,
wherein forming the insulating layer includes forming an insulating film in the groove.
3. The method as claimed in claim 1 , further wherein the plurality of charge storage layers are formed to be no higher than the top surface of the tunnel oxide film.
4. The method as claimed in claim 1 , wherein at least portion of the channel layer is disposed over the plurality of bit lines.
5. The method as claimed in claim 1 , wherein the insulating layer further comprises side faces oblique with respect to a surface of the substrate.
6. The method as claimed in claim 1 , wherein the plurality of charge storage layers are physically separated by the top surface of the tunnel oxide film.
7. The method as claimed in claim 1 , wherein the channel layer comprises a polysilicon layer.
8. The method as claimed in claim 1 , wherein the plurality of charge storage layers comprises silicon nitride films.
9. The method as claimed in claim 1 , wherein the substrate is an insulating substrate.
10. The method as claimed in claim 1 , further comprising: forming a plurality of word lines perpendicular to the plurality of bit lines.
11. The method as claimed in claim 10 , wherein the insulating layer is interposed between the word lines and the charge storage layers.
12. The method as claimed in claim 1 , wherein forming the charge storage layers includes forming charge storage layers by a sidewall technique.
13. The method as claimed in claim 1 , wherein forming the plurality of charge storage layers comprises isolating two portions of a single contiguous charge storage layer from each other via etching.
14. The method as claimed in claim 1 , wherein the plurality of charge storage layers includes floating gates.