Trench power MOSFET structure with high cell density and fabrication method thereof
First Claim
1. A fabrication method of a trench power MOSFET structure with a cell density comprising the steps of:
- forming at least a gate trench in a silicon substrate;
forming a gate dielectric layer lining exposed surfaces of the silicon substrate;
forming a gate polysilicon structure in the gate trench;
forming a passivation layer in the gate trench to cover the gate polysilicon structure;
forming a diffusion barrier layer on the passivation layer and on the surfaces of the silicon substrate after the step of forming the passivation layer in the gate trench, wherein a thickness of the diffusion barrier layer is in the range of 200-300 Å
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forming a body region having a first conductive type in the silicon substrate;
forming a source doped region by implanting impurities of a second conductive type into the body region;
removing a portion of the gate dielectric layer and the passivation layer so as to expose the gate polysilicon structure and the source doped region;
forming a dielectric spacer with a predetermined thickness on a sidewall of the gate trench;
depositing a metal layer on the exposed surfaces of the gate polysilicon structure and the source doped region;
forming a first self-aligned silicide layer on the gate polysilicon structure and a second self-aligned silicide layer on the source doped region by using a thermal process;
forming a dielectric structure in the gate trench to shield the first self-aligned silicide layer; and
forming a source metal layer on the dielectric structure and the second self-aligned silicide layer.
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Abstract
A fabrication method of a high cell density trench power MOSFET structure is provided. Form at least a gate trench in a silicon substrate and a gate dielectric layer on the silicon substrate. Form a gate polysilicon structure in the gate trench and cover by a passivation layer. Form a first-conductive-type body region in the silicon substrate and implant impurities with a second conductive type thereof to form a source doped region. Expose the gate polysilicon structure and the source doped region. Form a dielectric spacer having a predetermined thickness on a sidewall of the gate trench. Deposit metal on the gate polysilicon structure and the source doped region. A first and a second self-aligned silicide layer are respectively formed on the gate polysilicon structure and the source doped region. The dielectric spacer forms an appropriate distance between the first and the second self-aligned silicide layer.
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Citations
5 Claims
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1. A fabrication method of a trench power MOSFET structure with a cell density comprising the steps of:
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forming at least a gate trench in a silicon substrate; forming a gate dielectric layer lining exposed surfaces of the silicon substrate; forming a gate polysilicon structure in the gate trench; forming a passivation layer in the gate trench to cover the gate polysilicon structure; forming a diffusion barrier layer on the passivation layer and on the surfaces of the silicon substrate after the step of forming the passivation layer in the gate trench, wherein a thickness of the diffusion barrier layer is in the range of 200-300 Å
;forming a body region having a first conductive type in the silicon substrate; forming a source doped region by implanting impurities of a second conductive type into the body region; removing a portion of the gate dielectric layer and the passivation layer so as to expose the gate polysilicon structure and the source doped region; forming a dielectric spacer with a predetermined thickness on a sidewall of the gate trench; depositing a metal layer on the exposed surfaces of the gate polysilicon structure and the source doped region; forming a first self-aligned silicide layer on the gate polysilicon structure and a second self-aligned silicide layer on the source doped region by using a thermal process; forming a dielectric structure in the gate trench to shield the first self-aligned silicide layer; and forming a source metal layer on the dielectric structure and the second self-aligned silicide layer. - View Dependent Claims (2, 3, 4, 5)
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Specification