Interdigitated capacitors with a zero quadratic voltage coefficient of capacitance or zero linear temperature coefficient of capacitance
View Patent ↗Disclosed are an interdigitated capacitor and an interdigitated vertical native capacitor, each having a relatively low (e.g., zero) net coefficient of capacitance with respect to a specific parameter. For example, the capacitors can have a zero net linear temperature coefficient of capacitance (T cc ) to limit capacitance variation as a function of temperature or a zero net quadratic voltage coefficient of capacitance (V cc2 ) to limit capacitance variation as a function of voltage. In any case, each capacitor can incorporate at least two different plate dielectrics having opposite polarity coefficients of capacitance with respect to the specific parameter due to the types of dielectric materials used and their respective thicknesses. As a result, the different dielectric plates will have opposite effects on the capacitance of the capacitor that cancel each other out such that the capacitor has a zero net coefficient of capacitance with respect to specific parameter.
1. A capacitor comprising:
a first dielectric layer comprising a first dielectric material,
said first dielectric layer having a top surface and a first thickness, and
said first dielectric layer further having a first coefficient of capacitance with respect to a specific parameter;
first metal wires and second metal wires in said first dielectric layer at said top surface,
said first metal wires being interdigitated with said second metal wires, being physical separated from said second metal wires by spaces, and further being electrically isolated from said second metal wires by said first dielectric material in said spaces; and
a second dielectric layer on said top surface and extending laterally over said first metal wires and said second metal wires,
said second dielectric layer comprising a second dielectric material different from said first dielectric material and having a second thickness that is different from said first thickness, and
said second dielectric layer further having a second coefficient of capacitance with respect to said specific parameter,
said first coefficient of capacitance and said second coefficient of capacitance having opposite polarities, said spaces physically separating said first metal wires from said second metal wires being a predetermined length, and said first thickness to said second thickness being a predetermined ratio such that said capacitor has a specific net coefficient of capacitance of approximately zero with respect to said specific parameter.
2. The capacitor of claim 1 , further comprising a third dielectric layer having a third coefficient of capacitance with respect to said specific parameter so as to fine tune said specific net coefficient of capacitance to zero, said third dielectric layer being any one of the following:
within said first dielectric layer such that said first metal wires and said second metal wires extend vertically through said third dielectric layer;
stacked between said first dielectric layer and said second dielectric layer; and
stacked above said second dielectric layer.
3. The capacitor of claim 2 , said first dielectric layer, said second dielectric layer and said third dielectric layer comprising different dielectric materials.
4. The capacitor of claim 2 , said third dielectric layer being within said first dielectric layer and said second dielectric layer and said third dielectric layer comprising a same dielectric material.
5. The capacitor of claim 1 , said specific parameter comprising temperature and said first coefficient of capacitance and said second coefficient of capacitance each comprising a linear temperature coefficient of capacitance.
6. The capacitor of claim 1 , said specific parameter comprising voltage and said first coefficient of capacitance and said second coefficient of capacitance each comprising a quadratic voltage coefficient of capacitance.
7. The capacitor of claim 6 , said first dielectric layer comprising silicon oxide and having a negative quadratic voltage coefficient of capacitance and said second dielectric layer comprising any one of silicon nitride and aluminum oxide and having a positive quadratic voltage coefficient of capacitance.
8. The capacitor of claim 1 , further comprising:
additional first metal wires in said second dielectric layer aligned above and electrically connected to said first metal wires; and
additional second metal wires in said second dielectric layer aligned above and electrically connected to said second metal wires, said additional second metal wires further being interdigitated with and electrically isolated from said additional first metal wires.
9. The capacitor of claim 8 , further comprising a third dielectric layer having a third coefficient of capacitance with respect to said specific parameter so as to fine tune said specific net coefficient of capacitance to be equal to zero, said third dielectric layer being any one of the following:
within said first dielectric layer such that said first metal wires and said second metal wires extend vertically through said third dielectric layer;
within said second dielectric layer such that said additional first metal wires and said additional second metal wires extend vertically through said third dielectric layer; and
stacked between said first dielectric layer and said second dielectric layer.
10. A hardware description language (HDL) design structure encoded on a machine-readable data storage medium, said HDL design structure comprising data and instruction elements that are executable by a computer in a computer-aided design system in order to generate a machine-executable representation of a capacitor, said capacitor comprising:
a first dielectric layer comprising a first dielectric material,
said first dielectric layer having a top surface and a first thickness, and
said first dielectric layer further having a first coefficient of capacitance with respect to a specific parameter;
first metal wires and second metal wires in said first dielectric layer at said top surface, said first metal wires being interdigitated with said second metal wires, being physical separated form said second metal wires by spaces, and further being electrically isolated from said second metal wires by said first dielectric material; and
a second dielectric layer on said top surface and extending laterally over said first metal wires and said second metal wires,
said second dielectric layer comprising a second dielectric material different from said first dielectric material and having a second thickness that is different from said first thickness, and
said second dielectric layer further having a second coefficient of capacitance with respect to said specific parameter,
said first coefficient of capacitance and said second coefficient of capacitance having opposite polarities, said spaces physically separating said first metal wires from said second metal wires being a predetermined length, and said first thickness to said second thickness being a predetermined ratio such that said capacitor has a specific net coefficient of capacitance of approximately zero with respect to said specific parameter.
11. The capacitor of claim 1 , said specific parameter comprising voltage, said first dielectric material comprising silicon oxide having a negative quadratic voltage coefficient of capacitance, said second dielectric material comprising silicon nitride having a positive quadratic voltage coefficient of capacitance, and said predetermined ratio being one of the following:
1:1.7 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm;
1:1.2 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm; and,
1:1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 500 nm.
12. The capacitor of claim 1 , said specific parameter comprising voltage, said first dielectric material comprising silicon oxide having a negative quadratic voltage coefficient of capacitance, said second dielectric material comprising aluminum oxide having a positive quadratic voltage coefficient of capacitance, and said predetermined ratio being one of the following:
20.1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm;
43:1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm; and,
66:1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 500 nm.
13. A capacitor comprising:
a first dielectric layer comprising a first dielectric material,
said first dielectric layer having a top surface and a first thickness, and
said first dielectric layer further having a first quadratic voltage coefficient of capacitance with respect to a specific parameter, said specific parameter comprising voltage;
first metal wires and second metal wires in said first dielectric layer at said top surface,
said first metal wires being interdigitated with said second metal wires, being physical separated from said second metal wires by spaces, and further being electrically isolated from said second metal wires by said first dielectric material in said spaces; and
a second dielectric layer on said top surface and extending laterally over said first metal wires and said second metal wires,
said second dielectric layer comprising a second dielectric material different from said first dielectric material and having a second thickness that is different from said first thickness, and
said second dielectric layer further having a second quadratic voltage coefficient of capacitance with respect to said specific parameter,
said first quadratic voltage coefficient of capacitance and said second quadratic voltage coefficient of capacitance having opposite polarities, said spaces physically separating said first metal wires from said second metal wires being a predetermined length, and said first thickness to said second thickness being a predetermined ratio such that said capacitor has a specific net quadratic voltage coefficient of capacitance of approximately zero with respect to said specific parameter.
14. The capacitor of claim 13 , said first dielectric material comprising silicon oxide having a negative quadratic voltage coefficient of capacitance, said second dielectric material comprising silicon nitride having a positive quadratic voltage coefficient of capacitance, and said predetermined ratio being one of the following:
1:1.7 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm;
1:1.2 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm; and,
1:1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 500 nm.
15. The capacitor of claim 13 , said first dielectric material comprising silicon oxide having a negative quadratic voltage coefficient of capacitance, said second dielectric material comprising aluminum oxide having a positive quadratic voltage coefficient of capacitance, and said predetermined ratio being one of the following:
20.1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm;
43:1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 100 nm; and,
66:1 when said predetermined length of said spaces physically separating said first metal wires from said second metal wires is 500 nm.
16. The capacitor of claim 13 , further comprising a third dielectric layer having a third quadratic voltage coefficient of capacitance with respect to said specific parameter so as to fine tune said specific net coefficient of capacitance to zero, said third dielectric layer being any one of the following:
within said first dielectric layer such that said first metal wires and said second metal wires extend vertically through said third dielectric layer;
stacked between said first dielectric layer and said second dielectric layer; and
stacked above said second dielectric layer.
17. The capacitor of claim 16 , said first dielectric layer, said second dielectric layer and said third dielectric layer comprising different dielectric materials.
18. The capacitor of claim 16 , said third dielectric layer being within said first dielectric layer and said second dielectric layer and said third dielectric layer comprising a same dielectric material.
19. The capacitor of claim 13 , said first dielectric layer comprising silicon oxide and having a negative quadratic voltage coefficient of capacitance and said second dielectric layer comprising any one of silicon nitride and aluminum oxide and having a positive quadratic voltage coefficient of capacitance.
20. The capacitor of claim 13 , further comprising:
additional first metal wires in said second dielectric layer aligned above and electrically connected to said first metal wires; and
additional second metal wires in said second dielectric layer aligned above and electrically connected to said second metal wires, said additional second metal wires further being interdigitated with and electrically isolated from said additional first metal wires.