Abstract: The thickness of a palladium coating on copper (or another substrate) is measured by passing a cathodic current through a predetermined area of the coating in contact with an electrolytic solution and measuring the potential as a function of time. Protons from the electrolytic solution are electrochemically reduced to palladium hydride at cathodic potentials less negative than required for evolution of hydrogen. As formation of the PdH0.58 beta-phase throughout the Pd coating is completed, the cathodic potential increases rapidly to a cathodic potential plateau corresponding to evolution of hydrogen gas on the PdH0.58 surface. This step in the cathodic potential provides an endpoint time for the measurement. The absolute thickness of the Pd coating is calculated from the integrated cathodic charge passed up to the endpoint time and the predetermined area of the coating in contact with the electrolytic solution.

Abstract: Silicon ions in an alkaline etchant solution are analyzed by acidifying a sample of the etchant solution, adding fluoride ions in excess of the concentration required to react with all of the silicon ions, and using a fluoride ion specific electrode (FISE) to detect free fluoride ions in the resulting test solution. Good sensitivity and precision are provided by using a relatively acidic test solution and only a slight excess of fluoride ions, and limiting the analysis range to the maximum expected silicon concentration in the etchant solution.

Abstract: Silicon ions in an alkaline etchant solution are analyzed by acidifying a sample of the etchant solution, adding fluoride ions in excess of the concentration required to react with all of the silicon ions, and using a fluoride ion specific electrode (FISE) to detect free fluoride ions in the resulting test solution. Good sensitivity and precision are provided by using a relatively acidic test solution and only a slight excess of fluoride ions, and limiting the analysis range to the maximum expected silicon concentration in the etchant solution.

Abstract: The thickness of a palladium coating on copper (or another substrate) is measured by passing a cathodic current through a predetermined area of the coating in contact with an electrolytic solution and measuring the potential as a function of time. Protons from the electrolytic solution are electrochemically reduced to palladium hydride at cathodic potentials less negative than required for evolution of hydrogen. As formation of the PdH0.58 beta-phase throughout the Pd coating is completed, the cathodic potential increases rapidly to a cathodic potential plateau corresponding to evolution of hydrogen gas on the PdH0.58 surface. This step in the cathodic potential provides an endpoint time for the measurement. The absolute thickness of the Pd coating is calculated from the integrated cathodic charge passed up to the endpoint time and the predetermined area of the coating in contact with the electrolytic solution.

Abstract: An auxiliary leveler additive that cannot be analyzed by conventional CVS methods for acid copper plating baths is analyzed by cyclic voltammetry at a platinum rotating disk electrode from its effect on the anodic current at very positive potentials.

Abstract: The chloride concentration in an acid copper plating bath is determined from the chloride oxidation current measured under controlled hydrodynamic conditions at a noble metal electrode using specific voltammetric parameters. The measurement is made directly on the undiluted plating bath so that the chloride measurement is fast and no waste stream is generated.

Abstract: A simple titration method involving a single copper ion titrant detected by a copper ion specific electrode provides the concentrations of both copper ions and bath complexing agent (ethylene diamine, for example) in alkaline copper electroplating baths of the type used to deposit or thicken copper seed layers on silicon wafers. Standard addition of an excess of a strong complexing agent (EDTA, for example) and back-titration with the copper ion titrant yields the bath copper ion concentration, and continued titration to a second endpoint, preferably after addition of hydroxide to adjust the pH of the analysis solution, yields the total concentration of bath complexing agent. Based on these analyzes, the concentration of free bath complexing agent may be calculated. The method also provides direct determination of the free bath complexing agent concentration via standard addition of excess bath complexing agent to a sample of the plating bath and titration with the copper ion titrant.

Abstract: Boric acid is replenished in an electroplating bath via a replenishment solution comprising boric acid dissolved in pure water, in which the solubility at room temperature is comparable to that in the plating bath at operating temperature. The replenishment solution may be used to replace all or part of the water lost by evaporation. An automated device may be used to replenish boric acid in the electroplating bath.

Abstract: An auxiliary leveler additive that cannot be analyzed by conventional CVS methods for acid copper plating baths is analyzed by cyclic voltammetry at a platinum rotating disk electrode from its effect on the anodic current at very positive potentials.

Abstract: Low concentrations of silicon in an etchant solution are analyzed by adding a predetermined concentration of fluoride ions to a test solution comprising a predetermined volume of the etchant solution, and measuring the concentration of fluoride ions in the test solution. Reaction with silicon ions in the test solution reduces the concentration of fluoride ions, which are present in stoichiometric excess, so that the silicon concentration of the etchant solution can be calculated from the difference between the predetermined and measured concentrations of fluoride ions in the test solution. The method is especially suited for analysis of silicon nitride etchants comprising a high concentration of phosphoric acid.

Abstract: The stability of an electroless plating bath for depositing a metal (e.g., nickel) is determined by titrating a sample of the plating bath with a titrant comprising ions of a catalytic metal (e.g., palladium) and detecting hydrogen released at the titration endpoint. The quantity of titrant required to attain the endpoint provides a measure of the stability of the electroless plating bath.

Abstract: An additive breakdown product in an acid copper plating bath sample is detected by performing a voltammetric analysis for the leveler additive in two measurement solutions comprising different volume fractions of the copper plating bath sample in a background electrolyte. When the plating bath sample contains a substantial concentration of the additive breakdown product, the analyses for the first and second measurement solutions indicate different concentrations for the leveler additive in the plating bath sample. A comparison of the leveler additive concentrations indicated by the two analyses provides a measure of the concentration of the additive breakdown product.

Abstract: Methods and apparatus for real-time dynamic analysis of a chemical etching process are provided. The apparatus comprises an optical element (36) operative to pass a beam of electromagnetic radiation at least at two points in time through a liquid phase (42) comprising at least one chemical component and including an etchant, wherein the etchant is operative to etch a solid. A detector (60) is operative to perform an ex-situ non-contact scanning detection of the electromagnetic radiation subsequent to passing through the liquid phase in a near infra-red range (700-2500 nm) at the at least at two points in time so as to detect a change in an optical property of at least one of the at least one chemical component and the etchant.

Abstract: The 3-mercaptopropylsulfonic acid (MPSA) breakdown product of the bis(sodiumsulfopropyl)disulfide (SPS) additive used in acid copper plating baths accelerates copper electrodeposition and can be detected by cyclic voltammetric stripping (CVS) analysis. In the presence of oxygen, MPSA decomposes rapidly in acid copper sulfate baths so that the CVS stripping peak area (Ar) decreases on successive cycles. The slope of a plot of Ar vs. CVS cycle number (or time) or logarithm of the CVS cycle number (or time) provides a measure of the initial MPSA concentration.

Abstract: The concentration of citrate complexing agent in an electroless cobalt or nickel plating bath is determined by titrating a sample of the electroless plating bath containing a small concentration of free fluoride ion with a standard lanthanum nitrate solution. During the titration, La3+ ion first reacts preferentially with the citrate complexing agent and then with fluoride ion, which reduces the free fluoride ion concentration. The endpoint for the titration is indicated by a substantial decrease in the free fluoride ion concentration, which is detected via a fluoride ion specific electrode (ISE). The method can be used for analysis of other complexing agents.

Abstract: The concentration of citrate complexing agent in an electroless cobalt or nickel plating bath is determined by titrating a sample of the electroless plating bath containing a small concentration of free fluoride ion with a standard lanthanum nitrate solution. During the titration, La3+ ion first reacts preferentially with the citrate complexing agent and then with fluoride ion, which reduces the free fluoride ion concentration. The endpoint for the titration is indicated by a substantial decrease in the free fluoride ion concentration, which is detected via a fluoride ion specific electrode (ISE). The method can be used for analysis of other complexing agents.

Abstract: Relative concentrations of active suppressor additive species and suppressor breakdown contaminants in an acid copper electroplating bath are determined by cyclic voltammetric stripping (CVS) dilution titration analysis using two negative electrode potential limits. The analysis results for the more negative potential limit provide a measure of the suppressor additive concentration alone since the suppressor breakdowvn contaminants are not effective at suppressing the copper deposition rate at the more negative potentials. The analysis results for the less negative potential limit provide a measure of the combined concentrations of the suppressor additive and the suppressor breakdown contaminants. Comparison of the results for the two analyses yields a measure of the concentration of the suppressor breakdown contaminants relative to the suppressor additive concentration.

Abstract: In the present invention, the test reference electrode used for voltammetric analysis of a plating bath is calibrated relative to the zero-current point between metal plating and stripping at a rotating platinum disk electrode in the plating bath supporting electrolyte. This calibration is readily performed during the normal course of cyclic voltammetric stripping (CVS) or cyclic pulse voltammetric stripping (CPVS) plating bath analysis the need for additional instrumentation or removal of the test reference electrode from the analysis equipment. Automatic calibration of the reference electrode enabled by the present invention, saves labor, time and expense, and minimizes errors in the plating bath analysis.

Abstract: Relative concentrations of active suppressor additive species and suppressor breakdown contaminants in an acid copper electroplating bath are determined by cyclic voltammetric stripping (CVS) dilution titration analysis using two negative electrode potential limits. The analysis results for the more negative potential limit provide a measure of the suppressor additive concentration alone since the suppressor breakdown contaminants are not effective at suppressing the copper deposition rate at the more negative potentials. The analysis results for the less negative potential limit provide a measure of the combined concentrations of the suppressor additive and the suppressor breakdown contaminants. Comparison of the results for the two analyses yields a measure of the concentration of the suppressor breakdown contaminants relative to the suppressor additive concentration.

Abstract: The concentration of a reducing agent in an electroless bath for plating a first metal is determined from the effect of the reducing agent on the electrodeposition rate of a second metal. For electroless cobalt and nickel baths, a sample of the electroless plating bath is added to an acid copper plating solution and the copper electrodeposition rate is measured by cyclic voltammetric stripping (CVS) analysis. Separate analyses for hypophosphite and dimethylamineborane in baths employing both reducing agents are attained via selective decomposition of the dimethylamineborane in acidic solution.