Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2005-08-23
2005-08-23
Picardat, Kevin M. (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S643000, C438S653000, C438S674000, C438S678000, C438S687000, C438S783000, C438S787000
Reexamination Certificate
active
06933225
ABSTRACT:
Thin films are formed by atomic layer deposition, whereby the composition of the film can be varied from monolayer to monolayer during cycles including alternating pulses of self-limiting chemistries. In the illustrated embodiments, varying amounts of impurity sources are introduced during the cyclical process. A graded gate dielectric is thereby provided, even for extremely thin layers. The gate dielectric as thin as 2 nm can be varied from pure silicon oxide to oxynitride to silicon nitride. Similarly, the gate dielectric can be varied from aluminum oxide to mixtures of aluminum oxide and a higher dielectric material (e.g., ZrO2) to pure high k material and back to aluminum oxide. In another embodiment, metal nitride (e.g., WN) is first formed as a barrier for lining dual damascene trenches and vias. During the alternating deposition process, copper can be introduced, e.g., in separate pulses, and the copper source pulses can gradually increase in frequency, forming a graded transition region, until pure copper is formed at the upper surface. Advantageously, graded compositions in these and a variety of other contexts help to avoid such problems as etch rate control, electromigration and non-ohmic electrical contact that can occur at sharp material interfaces.
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Haukka Suvi P.
Raaijmakers Ivo
Werkhoven Christiaan J.
ASM International N.V.
Knobbe Martens Olson & Bear LLP
Picardat Kevin M.
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