Ferroelectric memory device and fabrication process thereof, fabrication process of a semiconductor device
View Patent ↗A ferroelectric memory device includes a field effect transistor formed over a semiconductor substrate and including first and second diffusion regions, an interlayer insulation film formed over the semiconductor substrate so as to cover the field effect transistor, a conductive plug formed in the interlayer insulation film in contact with the first diffusion region, and a ferroelectric capacitor formed over the interlayer insulation in contact with the conductive plug. The ferroelectric capacitor includes a ferroelectric film and upper and lower electrodes sandwiching the ferroelectric film respectively from above and below. The lower electrode is connected electrically to the conductive plug, and wherein a layer containing aluminum and oxygen is interposed between the conductive plug and the lower electrode, a layer containing nitrogen is interposed between the layer containing aluminum and oxygen and the lower electrode, and a self-aligned layer of a substance having a self-orientation is interposed between the layer containing nitrogen and the lower electrode.
1. A ferroelectric memory device, comprising:
a semiconductor substrate;
a field effect transistor formed over said semiconductor substrate, said field effect transistor including first and second diffusion regions;
an interlayer insulation film formed over said semiconductor substrate so as to cover said field effect transistor;
a conductive plug formed in said interlayer insulation film in contact with said first diffusion region; and
a ferroelectric capacitor formed over said interlayer insulation in contact with said conductive plug,
said ferroelectric capacitor comprising a ferroelectric film and upper and lower electrodes sandwiching said ferroelectric film respectively from above and below,
said lower electrode being connected electrically to said conductive plug,
a layer containing aluminum and oxygen being interposed between said the conductive plug and said lower electrode,
a layer containing nitrogen being interposed between said layer containing aluminum and oxygen and said lower electrode,
a self-aligned layer of a substance having a self-orientation being interposed between said layer containing nitrogen and said lower electrode.
2. The ferroelectric memory device as claimed in claim 1 , wherein said layer containing aluminum and oxygen comprises a TiAlN film having at least one oxygen atomic layer at a surface thereof.
3. The ferroelectric memory device as claimed in claim 2 , wherein said TiAlN film has a thickness of 50-100 nm.
4. The ferroelectric memory device as claimed in claim 1 , wherein said layer containing nitrogen contains at least one layer of nitrogen atomic layer.
5. The ferroelectric memory device as claimed in claim 1 , wherein a surface of said layer containing nitrogen is terminated with hydrogen.
6. The ferroelectric memory device as claimed in claim 1 , wherein said ferroelectric film has a (111) orientation.
7. The ferroelectric memory device as claimed in claim 1 , wherein said self-aligned layer is formed of one or more substances selected from the group consisting of Ti, Ir, Pt, PZT, SrRuO 3 , Ru, TiN, TiAlN, Al, Cu and IrOx.
8. The ferroelectric memory device as claimed in claim 1 , wherein said conductive plug comprises one or more substances selected from the group consisting of Si, Ti, TiN, TiAlN, W, Al, Cu, Ru and SrRuO 3 .
9. A method of fabricating a ferroelectric memory apparatus, comprising the steps of:
forming an interlayer insulation film over a semiconductor substrate over which a transistor is formed so as to cover said transistor;
forming a conductive plug in said interlayer insulation film in contact with a diffusion region of said transistor; and
forming a ferroelectric capacitor over said conductive plug by consecutively stacking a lower electrode, a ferroelectric film and an upper electrode,
wherein there is provided, after said step of forming said conductive plug but before said step of forming said lower electrode, the steps of: forming a layer containing aluminum and oxygen on said interlayer insulation film and a surface of said conductive plug; forming a layer containing nitrogen on a surface of said layer containing aluminum and oxygen; and forming a self-alignment film over said layer containing nitrogen.
10. The method as claimed in claim 9 , wherein said step of forming said layer containing oxygen comprises the steps of deposing a TiAlN on said surface of said interlayer insulation film and said contact plug; and reacting oxygen radicals upon said TiAlN film.
11. The method as claimed in claim 9 , wherein said step of forming said layer containing nitrogen comprises the step of reacting NH radicals to a surface of said layer containing oxygen.
12. The method as claimed in claim 9 , wherein said step of forming said layer containing nitrogen comprises the step of reacting nitrogen radicals and hydrogen radicals to a surface of said layer containing oxygen.
13. The method as claimed in claim 9 , wherein said step of forming said self-alignment film is conducted at a temperature of 300° C. or less.
14. The method as claimed in claim 9 , wherein said step of forming said self-alignment film comprises the step of depositing a Ti film by a sputtering process.
15. A method of fabricating a semiconductor device having a function film, comprising the steps of:
forming an interlayer insulation film over a semiconductor substrate over which a transistor is formed so as to cover said transistor;
forming a conductive plug in said interlayer insulation film in contact with a diffusion region of said transistor; and
forming a functional film over said conductive plug,
wherein there is provided, after said step of forming said conductive plug but before said step of forming said functional film, the steps of: forming a layer containing aluminum and oxygen on said interlayer insulation film and a surface of said conductive plug; forming a layer containing nitrogen on a surface of said layer containing aluminum and oxygen; and forming a self-alignment film over said layer containing nitrogen.