Claims
- 1. A method for manufacturing a three-dimensional, deep-trench, high-density ROM, the method comprising the steps of:performing ion implantation to form a plurality of parallel bit lines on a surface of a silicon substrate; forming a photoresist layer to expose a plurality of channel regions of the substrate where non-conducting memory cells are desired; performing an etching operation, using the photoresist layer as a mask, to form a trench in each of the channel regions, each trench having a trench depth larger than a depth of each of the bit lines; forming a second photoresist layer to expose a plurality of channel regions of the substrate where conducting memory cells are desired using the second photoresist layer as a mask, performing an etching operation to form a plurality of shallow trenches, each shallow trench having a depth approximately equal to the depth of each of the bit lines sequentially forming a gate oxide layer and a polysilicon layer on the surface of the silicon substrate; and defining the gate oxide and polysilicon layers to form a plurality of word lines that are perpendicular to the plurality of bit lines.
- 2. The method according to claim 1, further comprising the steps of:prior to the ion implantation step, forming a plurality of field oxide layers as masks; and after the ion implantation step, removing the field oxide layers to create arc-shaped channel regions in the silicon substrate.
- 3. The method according to claim 1, wherein the ion implantation operation is performed using an energy of 50 to 100 KeV and an ion concentration of approximately 10 to 1016 atoms/cm2.
- 4. The method according to claim 1, further comprising the steps of:before the photoresist layer formation step, forming a pad oxide layer on the substrate surface; and after the completion of the etching step, removing the pad oxide layer.
- 5. The method according to claim 4, wherein the pad oxide layer is formed in a pipe oven containing wet oxygen and at a temperature of 850° C. to 950° C.
Priority Claims (1)
Number |
Date |
Country |
Kind |
86104851 |
Apr 1997 |
TW |
|
Parent Case Info
This is a division of application Ser. No. 08/915,400, filed Aug. 20, 1997 now U.S. Pat. No. 6,018,186—all of which are incorporated herein by reference.
US Referenced Citations (9)