Fabrication of stacked MOS devices utilizing lateral seeding and a plurality of separate implants at different energies
First Claim
1. A process for the fabrication of vertically integrated MOS devices comprising the ordered steps of:
- forming field oxide regions on a semiconductor substrate;
forming a first gate oxide region on the substrate;
forming a gate on the first oxide region;
forming a second gate oxide region over the gate;
depositing a polycrystalline semiconductor layer over the gate and oxide regions so as to directly contact the substrate of at least one contact position;
heating, melting and then cooling the polycrystalline on the substrate to promote lateral seeding thereof from the substrate semiconductor at the or each contact position; and
after lateral seeding of the polycrystalline, forming sources and drains in both the substrate and recrystallized polycrystalline semiconductor by ion implantation using a plurality of separate implants at different energies to achieve desired concentration of ions at a desired depth within the recrystallized and substrate silicon.
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Abstract
In a process for manufacturing vertically integrated MOS devices and circuits, gate oxide and a gate are formed on a semiconductor substrate such as a silicon substrate. A layer of polysilicon is then deposited over the wafer, the polysilicon contacting the substrate silicon through a window in the gate oxide. The substrate silicon and the polysilicon are then laser melted and cooled under conditions that encourage crystal seeding from the substrate into the polysilicon over the gate. Subsequently, ions are implanted into the silicon substrate and the polysilicon to form source and drain regions. By introducing the source and drain dopants after melt associated seeding of the polysilicon, the risk of dopant diffusion into the device channel regions is avoided.
85 Citations
12 Claims
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1. A process for the fabrication of vertically integrated MOS devices comprising the ordered steps of:
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forming field oxide regions on a semiconductor substrate; forming a first gate oxide region on the substrate; forming a gate on the first oxide region; forming a second gate oxide region over the gate; depositing a polycrystalline semiconductor layer over the gate and oxide regions so as to directly contact the substrate of at least one contact position; heating, melting and then cooling the polycrystalline on the substrate to promote lateral seeding thereof from the substrate semiconductor at the or each contact position; and after lateral seeding of the polycrystalline, forming sources and drains in both the substrate and recrystallized polycrystalline semiconductor by ion implantation using a plurality of separate implants at different energies to achieve desired concentration of ions at a desired depth within the recrystallized and substrate silicon. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification