Method for forming a shielded gate trench FET with the shield and gate electrodes being connected together
First Claim
Patent Images
1. A method of forming a field effect transistor (FET), comprising:
- forming a trench in a semiconductor region;
forming a shield dielectric layer lining lower sidewalls and a bottom surface of the trench;
forming a shield electrode in a lower portion of the trench;
forming a dielectric layer along upper trench sidewalls and over the shield electrode;
forming a gate electrode in the trench over the shield electrode; and
forming an interconnect layer connecting the gate electrode and the shield electrode.
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Abstract
A method of forming a field effect transistor includes the following steps. A trench is formed in a semiconductor region, and a shield dielectric layer lining lower sidewalls and a bottom surface of the trench is formed. A shield electrode is formed in a lower portion of the trench, and a dielectric layer is formed along upper trench sidewalls and over the shield electrode. A gate electrode is formed in the trench over the shield electrode, and an interconnect layer connecting the gate electrode and the shield electrode is formed.
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Citations
10 Claims
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1. A method of forming a field effect transistor (FET), comprising:
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forming a trench in a semiconductor region; forming a shield dielectric layer lining lower sidewalls and a bottom surface of the trench; forming a shield electrode in a lower portion of the trench; forming a dielectric layer along upper trench sidewalls and over the shield electrode; forming a gate electrode in the trench over the shield electrode; and forming an interconnect layer connecting the gate electrode and the shield electrode. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of forming a field effect transistor (FET) in a semiconductor die comprising an active region and a non-active region, the method comprising:
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forming a plurality of trenches in the active region of the die, the plurality of trenches extending into a semiconductor region; forming a first polysilicon layer filling each trench and extending over a mesa region in the non-active region of the die. recessing the first polysilicon layer into each trench so as to form a shield electrode in a bottom portion of each trench, the shield electrode in each trench maintaining continuity with those portions of the first polysilicon layer extending into the mesa region; forming a dielectric layer by oxidation of silicon such that the dielectric layer lines;
(i) exposed upper sidewalls of each trench, (ii) an upper surface of each shield electrode, and (iii) a surface area of the first polysilicon layer in the mesa region;forming a second polysilicon layer filling each trench and extending over the dielectric layer in the mesa region; recessing the second polysilicon layer into each trench so as to form a gate electrode in an upper portion of each trench, the gate electrode in each trench maintaining continuity with those portions of the second polysilicon layer extending into the mesa region; forming one or more contact openings in those portions of the second polysilicon layer and the dielectric layer extending into the mesa region so as to expose a surface area of the first polysilicon layer through the contact openings; and forming a gate interconnect layer filling the one or more contact openings to thereby electrically contact the first and second polysilicon layers together. - View Dependent Claims (8, 9)
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10. A method of forming a field effect transistor (FET), comprising:
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forming a plurality of trenches extending into a semiconductor region; forming a shield electrode in a bottom portion of each trench; forming a gate electrode in an upper portion of each trench over the shield electrode; and forming a gate interconnect layer electrically connecting the shield electrode and the gate electrode.
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Specification