Forming heaters for phase change memories
View Patent ↗A heater for a phase change memory may be formed by depositing a first material into a trench such that the material is thicker on the side wall than on the bottom of the trench. In one embodiment, because the trench side walls are of a different material than the bottom, differential deposition occurs. Then a heater material is deposited thereover. The heater material may react with the first material at the bottom of the trench to make Ohmic contact with an underlying metal layer. As a result, a vertical heater may be formed which is capable of making a small area contact with an overlying chalcogenide material.
1. A method comprising: forming a heater for a phase change memory by differentially depositing a first material over a vertical surface and a horizontal surface by a single deposition step wherein deposition of the first material forms a layer on the vertical surface having a thickness that is greater than a thickness of a layer on the horizontal surface, and then depositing a heater material over the first material.
2. The method of claim 1 including using atomic layer deposition.
3. The method of claim 2 including using atomic layer deposition of boron.
4. The method of claim 3 including depositing the heater material on said first material and causing a reaction to occur between the first material and the heater material such that Ohmic contact is achieved between the heater material and the horizontal surface.
5. The method of claim 4 including forming the horizontal surface of metal and forming a vertical surface of dielectric and using a deposition process that deposits more of said first material on dielectric than on said metal.
6. The method of claim 5 including forming a vertical heater.
7. A method comprising:
forming a layer on a vertical surface and a horizontal surface, the layer being thicker on said vertical surface than said horizontal surface;
depositing a material to form a heater for a phase change memory on said layer; and
causing the material to react with the layer on the horizontal surface so as to make physical contact with said horizontal surface.
8. The method of claim 7 including forming said layer of boron.
9. The method of claim 8 including forming the vertical surface of dielectric and forming the horizontal surface of metal.
10. The method of claim 7 including depositing a boron containing layer on said material to form a structure.
11. The method of claim 10 including planarizing said structure and depositing a chalcogenide in physical and electrical contact with said material.