Hardmask designs for dry etching FeRAM capacitor stacks
First Claim
1. A ferroelectric capacitor formed over a semiconductor substrate, the ferroelectric capacitor comprising:
- a bottom electrode formed over the semiconductor substrate, said bottom electrode comprised of a bottom electrode material;
a top electrode formed over said bottom electrode and comprised of a first electrode material;
a ferroelectric material situated between said top electrode and said bottom electrode; and
a hardmask formed on said top electrode and comprising a bottom hardmask layer and a top hardmask layer formed on said bottom hardmask layer, said top hardmask layer able to with stand etchants used to etch said bottom electrode, said top electrode, and said ferroelectric material to leave said bottom hardmask layer substantially unremoved during said etch and said bottom hardmask layer being comprised of a conductive material which substantially acts as a hydrogen diffusion barrier.
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Abstract
An embodiment of the instant invention is a ferroelectric capacitor formed over a semiconductor substrate, the ferroelectric capacitor comprising: a bottom electrode formed over the semiconductor substrate, the bottom electrode comprised of a bottom electrode material (304 of FIG. 4a); a top electrode formed over the bottom electrode and comprised of a first electrode material (306 and 308 of FIG. 4a); a ferroelectric material (306 of FIG. 4a) situated between the top electrode and the bottom electrode; and a hardmask formed on the top electrode and comprising a bottom hardmask layer (402 of FIG. 4a) and a top hardmask layer (408 of FIG. 4a) formed on the bottom hardmask layer, the top hardmask layer able to with stand etchants used to etch the bottom electrode, the top electrode, and the ferroelectric material to leave the bottom hardmask layer substantially unremoved during the etch and the bottom hardmask layer being comprised of a conductive material which substantially acts as a hydrogen diffusion barrier.
320 Citations
19 Claims
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1. A ferroelectric capacitor formed over a semiconductor substrate, the ferroelectric capacitor comprising:
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a bottom electrode formed over the semiconductor substrate, said bottom electrode comprised of a bottom electrode material;
a top electrode formed over said bottom electrode and comprised of a first electrode material;
a ferroelectric material situated between said top electrode and said bottom electrode; and
a hardmask formed on said top electrode and comprising a bottom hardmask layer and a top hardmask layer formed on said bottom hardmask layer, said top hardmask layer able to with stand etchants used to etch said bottom electrode, said top electrode, and said ferroelectric material to leave said bottom hardmask layer substantially unremoved during said etch and said bottom hardmask layer being comprised of a conductive material which substantially acts as a hydrogen diffusion barrier. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A ferroelectric capacitor formed over a semiconductor substrate, the ferroelectric capacitor comprising:
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a bottom diffusion barrier formed over the semiconductor substrate, said bottom diffusion barrier comprised of a first conductive material which substantially acts as a hydrogen diffusion barrier;
a bottom electrode formed on said bottom diffusion barrier and comprised of a bottom electrode material;
a top electrode formed over said bottom electrode and comprised of a first electrode material;
a ferroelectric material situated between said top electrode and said bottom electrode; and
a hardmask formed on said top electrode and comprising a bottom hardmask layer and a top hardmask layer formed on said bottom hardmask layer, said top hardmask layer able to with stand etchants used to etch said bottom diffusion barrier, said bottom electrode, said top electrode, and said ferroelectric material so as to leave said bottom hardmask layer substantially unremoved during said etch and said bottom hardmask layer being comprised of a second conductive material which substantially acts as a hydrogen diffusion barrier. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification