Controlling profiles of replacement gates
First Claim
1. A method comprising:
- forming a dummy gate electrode layer over a semiconductor region;
forming a mask strip over the dummy gate electrode layer;
performing a first etching process using the mask strip as a first etching mask to pattern an upper portion of the dummy gate electrode layer, with a remaining portion of the upper portion of the dummy gate electrode layer forming an upper part of a dummy gate electrode;
forming a protection layer on sidewalls of the upper part of the dummy gate electrode;
performing a second etching process on a lower portion of the dummy gate electrode layer to form a lower part of the dummy gate electrode, wherein the protection layer and the mask strip in combination are used as a second etching mask; and
replacing the dummy gate electrode and an underlying dummy gate dielectric with a replacement gate stack.
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Abstract
A method includes forming a dummy gate electrode layer over a semiconductor region, forming a mask strip over the dummy gate electrode layer, and performing a first etching process using the mask strip as a first etching mask to pattern an upper portion of the dummy gate electrode layer. A remaining portion of the upper portion of the dummy gate electrode layer forms an upper part of a dummy gate electrode. The method further includes forming a protection layer on sidewalls of the upper part of the dummy gate electrode, and performing a second etching process on a lower portion of the dummy gate electrode layer to form a lower part of the dummy gate electrode, with the protection layer and the mask strip in combination used as a second etching mask. The dummy gate electrode and an underlying dummy gate dielectric are replaced with a replacement gate stack.
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Citations
20 Claims
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1. A method comprising:
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forming a dummy gate electrode layer over a semiconductor region; forming a mask strip over the dummy gate electrode layer; performing a first etching process using the mask strip as a first etching mask to pattern an upper portion of the dummy gate electrode layer, with a remaining portion of the upper portion of the dummy gate electrode layer forming an upper part of a dummy gate electrode; forming a protection layer on sidewalls of the upper part of the dummy gate electrode; performing a second etching process on a lower portion of the dummy gate electrode layer to form a lower part of the dummy gate electrode, wherein the protection layer and the mask strip in combination are used as a second etching mask; and replacing the dummy gate electrode and an underlying dummy gate dielectric with a replacement gate stack. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method comprising:
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forming isolation regions extending into a semiconductor substrate; forming a semiconductor fin protruding higher than the isolation regions; forming a dummy gate dielectric on the semiconductor fin; forming a dummy gate electrode layer over the dummy gate dielectric; performing a first etching process on an upper portion of the dummy gate electrode layer, wherein the first etching process is stopped when a top surface of a lower portion of the dummy gate electrode layer is at an intermediate level between a top surface and a bottom surface of the dummy gate electrode layer; depositing a protection layer; removing horizontal portions of the protection layer, with a vertical portion of the protection layer encircling a remaining upper portion of the dummy gate electrode layer; and performing a second etching process to etch the lower portion of the dummy gate electrode layer, with the protection layer protecting the remaining upper portion of the dummy gate electrode layer during the second etching process. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method comprising:
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forming a polysilicon layer; performing a first etching process on the polysilicon layer, with a remaining portion of the polysilicon layer forming a polysilicon strip as a result of the first etching process, wherein the first etching process comprises; etching an upper portion of the polysilicon layer; forming a protection layer on a top surface and sidewalls of a remaining portion of the upper portion of the polysilicon layer; and after the protection layer is formed, etching a lower portion of the polysilicon layer; performing a second etching process on the polysilicon strip to make sidewalls of the lower portion of the polysilicon strip to be more tapered than before the second etching process, wherein the upper portion of the polysilicon strip is protected from the second etching process; and forming dielectric layers embedding the polysilicon strip therein. - View Dependent Claims (17, 18, 19, 20)
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Specification