Semiconductor device and method of fabricating the same
View Patent ↗A semiconductor device includes a semiconductor substrate which has a major surface and a MOS transistor which has a gate and first and second diffusion regions and which is formed on the major surface. The semiconductor device also includes a laminated structure of a SOG layer, wherein the laminated structure is composed of a base layer and a surface layer formed on the base layer and is formed over the MOS transistor and wherein the surface layer is denser than the base layer.
1. A method of fabricating a semiconductor device comprising:
forming a SOG layer over a MOS transistor formed on a semiconductor substrate;
converting a surface portion of the SOG layer into a dense layer which is denser than a bottom portion of the SOG layer;
removing a first portion of the dense layer to expose a surface of the bottom portion of the SOG layer by a first etching;
removing a second portion which corresponds to the exposed surface of the bottom portion of the SOG layer to expose a diffusion region of the MOS transistor by a second etching; and
forming a conductive material within a space in which the first and second portions are removed.
2. A method of fabricating a semiconductor device as set forth claim 1 , wherein said converting step comprises implanting ions into the surface portion of the SOG layer.
3. A method of fabricating a semiconductor device as set forth claim 1 , wherein the first etching is an anisotropic etching and the second etching is an isotropic etching.
4. A method of fabricating a semiconductor device as set forth in claim 1 , wherein the first etching is a dry etch, and the second etching is a wet etch.
5. A method of fabricating a semiconductor device as set forth in claim 1 , further comprising:
forming a protective film on a top and on sides of a gate electrode of the MOS transistor, before said forming a SOG layer, wherein the SOG layer and the protective film are different materials.
6. A method of fabricating a semiconductor device as set forth in claim 5 , wherein the protective film is silicon nitride.
7. A method of fabricating a semiconductor device comprising:
forming MOS transistors including gate electrodes on a substrate;
forming protective films on top and side surfaces of the gate electrodes;
forming an SOG layer that covers the MOS transistors and the substrate;
converting the SOG layer so as to include a first layer on a second layer, wherein the first layer is denser than the second layer;
etching a first opening in the first layer of the SOG layer to expose a top surface of the second layer of the SOG layer;
etching a second opening in the exposed top surface of the second layer of the SOG layer to expose a surface of the substrate between the MOS transistors and to expose the protective film on the side surface of at least one of the MOS transistors; and
forming a conductive material within the first and second openings.
8. A method of fabricating a semiconductor device as set forth in claim 7 , wherein said converting comprises implanting ions into a surface portion of the SOG layer.
9. A method of fabricating a semiconductor device as set forth in claim 7 , wherein the protective film is silicon nitride.
10. A method of fabricating a semiconductor device as set forth in claim 7 , wherein said etching a first opening comprises anisotropic etching, and said etching a second opening comprises isotropic etching.
11. A method of fabricating a semiconductor device as set forth in claim 7 , wherein said etching a first opening comprises dry etching, and said etching a second opening comprises wet etching.
12. A method of fabricating a semiconductor device as set forth in claim 7 , wherein the exposed surface of the substrate between the MOS transistors is a common source/drain region of the MOS transistors.