Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – Insulated gate formation
Reexamination Certificate
2002-06-28
2004-11-23
Kielin, Erik J. (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
Insulated gate formation
C438S785000, C438S786000
Reexamination Certificate
active
06821873
ABSTRACT:
FIELD OF THE INVENTION
The invention is generally related to the field of forming high dielectric constant (high-&kgr;) films in semiconductor devices and more specifically to forming high-&kgr; gate dielectrics.
BACKGROUND OF THE INVENTION
As semiconductor devices have scaled to smaller and smaller dimensions, the gate dielectric thickness has continued to shrink. Although further scaling of devices is still possible, scaling of the gate dielectric thickness has almost reached its practical limit with the conventional gate dielectric material, silicon dioxide. Further scaling of silicon dioxide gate dielectric thickness will involve a host of problems: extremely thin layers allow for large leakage currents due to direct tunneling through the oxide. Because such layers are formed literally from a few layers of atoms, exacting process control is required to repeatably produce such layers. Uniformity of coverage is also critical because device parameters may change dramatically based on the presence or absence of even a single monolayer of dielectric material. Finally, such thin layers form poor diffusion barriers to impurities.
Realizing the limitations of silicon dioxide, researchers have searched for alternative dielectric materials which can be formed in a thicker layer than silicon dioxide and yet still produce the same field effect performance. This performance is often expressed as “equivalent oxide thickness”: although the alternative material layer may be thick, it has the equivalent effect of a much thinner layer of silicon dioxide (commonly called simply “oxide”). In some instances, silicon dioxide has been replaced with a SiON. However, even higher-K dielectrics will soon be needed. Some films currently being investigated include deposited oxides or nitrides such as HfSiO, HfSiON, AlON, and AlZrO. Manufacturable processes for incorporating these materials are needed.
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Milton Ohring, “The Materials Science of Thin Films,” Academic Press, San Diego, CA, 1992, pp. 8-9.
Colombo Luigi
Rotondaro Antonio L. P.
Visokay Mark R.
Brady III W. James
Garner Jacqueline J.
Kielin Erik J.
Smoot Stephen W.
Telecky , Jr. Frederick J.
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