Method for BEOL resistor tolerance improvement using anodic oxidation
AssigneeInternational Business Machines Corporation
InventorsJohn M. Cotte, Kenneth J. Stein, Seshadri Subbanna, Richard P. Volant
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Abstract
A method of improving the tolerance of a back-end-of-the-line (BEOL) thin film resistor is provided. Specifically, the method of the present invention includes an anodization step which is capable of converting a portion of base resistor film into an anodized region. The anodized resistor thus formed has a sheet resistivity that is higher than that of the base resistor film.
Claims18
A method for improving the tolerance of a back-end-of-the-line (BEOL) thin film resistor comprising:
- (a) forming a base resistor film on at least one interconnect level of an integrated circuit, said base resistor film having a first sheet resistivity value;
- (b) subjecting said base resistor film to anodic oxidation so as to convert a portion of said base resistor film into an anodized region thereby increasing the first sheet resistivity value to a second sheet resistivity value;
- and
- (c) removing portions of said base resistor film and anodized region so as to form at least one trimmed resistor having said second sheet resistivity value on said at least one interconnect level.
A method for improving the tolerance of a back-end-of-the-line (BEOL) thin film resistor comprising:
- (a) forming a base resistor film on at least one interconnect level of an integrated circuit;
- (b) measuring the base resistor film's thickness and converting the same to a first sheet resistivity value;
- (c) subjecting said base resistor film to anodic oxidation so as to convert a portion of said base resistor film into an anodized region thereby increasing the first sheet resistivity value to a second sheet resistivity value;
- said anodic oxidization comprising using an applied voltage that is based on the following equation:
- V
- A
-
-
- N
-
-
- O
-
-
- D
- =
- (
- Δ
-
-
- R
- R
- i
- ×
- C
- A
- )
-
- t
- wherein
- VANOD=Anodization voltage (volts);
- ΔR=Resistance change (ohms);
- Ri=Initial resistance (ohms);
- CA=Anodization factor (Angstroms/volts);
- t=Initial film thickness (Angstroms);
- and
- (d) removing portions of said base resistor film and anodized region so as to form at least one trimmed resistor having said second sheet resistivity value on said at least one interconnect level.
A method for improving the tolerance of a back-end-of-the-line (BEOL) thin film resistor comprising:
- forming a base resistor film on at least one interconnect level of an integrated circuit, said base resistor film having a first sheet resistivity value;
- subjecting said base resistor film to anodic oxidation so as to convert a portion of said base resistor film into an anodized region thereby increasing the first sheet resistivity value to a second sheet resistivity value;
- and
- removing portions of said base resistor film and anodized region so as to form at least one trimmed resistor having said second sheet resistivity value on said at least one interconnect level, wherein said anodic oxidation comprises applying a voltage to an electrolytic bath, said voltage being based on the following equation:
- V
- A
-
-
- N
-
-
- O
-
-
- D
- =
- (
- Δ
-
-
- R
- R
- i
- ×
- C
- A
- )
-
- t
- wherein
- VANOD=Anodization voltage (volts);
- ΔR=Resistance change (ohms);
- Ri=Initial resistance (ohms);
- CA=Anodization factor (Angstroms/volts);
- t=Initial film thickness (Angstroms).
Dependencies are inferred from the claim text.