Technique to Selectively Dope Semiconductor Trench Walls and Bottom
Original Publication Date: 1988-Jan-01
Included in the Prior Art Database: 2005-Feb-14
Semiconductor memory cells utilizing trench storage capacitors can have the trench side walls and bottom dopant characteristics tailored to a designer's specifications. By using the angular shadowing capabilities of an ion implant (I/I) tool, a dopant can be implanted on side walls of a storage trench which is different from a dopant used on the bottom of the same trench. It is also possible to tailor the trench side walls so that opposite side walls have different dopants. To implant trench side walls, wafers are mounted on seven degree angle plates located at fixed positions around the perimeter of a disk as shown in Fig. 1.