Novellus Systems Incorporated

Shawn D Hancock

Jon Henri

Pramod Subramonium

Edward J McInerney

Zhiyuan Fang

Thomas M Pratt

Mike Pierce

Provided are plasma enhanced chemical vapor deposition methods of depositing smooth and conformal ashable hard mask films on substrates containing raised or recessed features. The methods involve using precursors having relatively high C:H ratios, such as acetylene (C:H ratio of 1), and plasmas having low ion energies and fluxes. According to various embodiments, the methods involve depositing smooth ashable hard mask films using high frequency radio frequency-generated plasmas with no low frequency component and/or relatively high pressures. Also provided are methods of depositing ashable hard mask films having good selectivity and improved side wall coverage and roughness. The methods involve depositing a first ashable hard mask film on a substrate having a feature using a process optimized for selectivity and/or optical properties and then depositing a smoothing layer on the first ashable hard mask film using an HF-only process.

Methods of depositing smooth and conformal ashable hard mask films

Provided are plasma enhanced chemical vapor deposition methods of depositing smooth and conformal ashable hard mask films on substrates containing raised or recessed features. The methods involve using precursors having relatively high C:H ratios, such as acetylene (C:H ratio of 1), and plasmas having low ion energies and fluxes. According to various embodiments, the methods involve depositing smooth ashable hard mask films using high frequency radio frequency-generated plasmas with no low frequency component and/or relatively high pressures (e.g., 2-5 Torr). Also provided are methods of depositing ashable hard mask films having good selectivity and improved side wall coverage and roughness. The methods involve depositing a first ashable hard mask film on a substrate having a feature using a process optimized for selectivity and/or optical properties and then depositing a smoothing layer on the first ashable hard mask film using an HF-only process.

A multi-station processing chamber in which incompatible processes are performed includes multiple pedestals positioned in wells with annular gaps around the pedestals. Showerheads located above the pedestals flow reactive gases over substrates located on the pedestals. The reactive gases are drawn through the annular gaps by a pressure gradient. The reactive gases are then pumped out of the wells through an exhaust port. The narrow annular gap permits little recirculation of the reactive gases one they are drawn into the wells. Moreover, the showerheads are flush with ceiling of the chamber and the wells contain smooth contours to minimize dead space in the chamber thereby reducing residence time of the reactive gases. An indexing plate is used to lift the substrates off the pedestals and to accurately position the substrates at the next processing station. In one embodiment a purge plate located on the ceiling of the chamber between the showerheads flows an inert gas, such as argon, to further assist in maintaining a separation between the reactive gases. Thus, while one process, such as a silane initiation is performed at one station, other stations may contemporaneously perform an incompatible process, such as a tungsten hexafluoride-silane nucleation process and hydrogen reduction, thereby increasing throughput.

Isolation of incompatible processes in a multi-station processing chamber

A multi-station processing chamber in which incompatible processes are performed includes multiple pedestals positioned in wells with annular gaps around the pedestals. Showerheads located above the pedestals flow reactive gases over substrates located on the pedestals. The reactive gases are drawn through the annular gaps by a pressure gradient. The reactive gases are then pumped out of the wells through an exhaust port. The narrow annular gap permits little recirculation of the reactive gases once they are drawn into the wells. Moreover, the showerheads are flush with ceiling of the chamber and the wells contain smooth contours to minimize dead space in the chamber thereby reducing residence time of the reactive gases. An indexing plate is used to lift the substrates off the pedestals and to accurately position the substrates at the next processing station. In one embodiment a purge plate located on the ceiling of the chamber between the showerheads flows an inert gas, such as argon, to further assist in maintaining a separation between the reactive gases. Thus, while one process, such as a silane initiation is performed at one station, other stations may contemporaneously perform an incompatible process, such as a tungsten hexafluoride--silane nucleation process and hydrogen reduction, thereby increasing throughput.

A tungsten (W) film is formed on a surface of a semiconductor substrate by providing to that surface gas mixtures tailored for both reduced gas phase nucleation of particulates (GPN) and attack of exposed silicon (Si) or titanium (Ti) surfaces (Device Attack) while maintaining a high W deposition rate. An initiation step is performed where the surface is preconditioned with hydrogen (H.sub.2) and silane (SiH.sub.4). A subsequent nucleation step then uses a mixture of H.sub.2 and SiH.sub.4 to reduce tungsten hexafluoride (WF.sub.6) and thus form a first thickness of the W film. In some embodiments, an alternate gas mixture can be employed to form a second thickness of W on the surface of the semiconductor substrate.

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Alviso, CA, United States of America

Shawn D Hancock