Abstract: A camera may capture reflected light from the surface of the wafer during a semiconductor process that adds or removes material from the wafer, such as an etch process. To accurately determine an endpoint for the process, a camera sampling rate and light source intensity may be optimized in the process recipe. Optimizing the light source intensity may include characterizing light intensities that will be reflected from the waiver using an image of the wafer. Pixel intensities may be used to adjust the light source intensity to compensate for more complex wafer patterns. Optimizing the camera sampling rates may include nondestructively rotating a view of the wafer and converting the sampled intensities to the frequency domain. The camera sampling rate may be increased or decreased to remove spatial noise from the image without oversampling unnecessarily. These optimized parameters may then generate a clean, repeatable trace for endpoint determination.

Abstract: An analytical chemistry apparatus and method for introducing a reagent into a flowing stream of liquid carrier in order to quantitatively analyze one or more components of a sample added into the carrier. The reagent is permeated across a short section of membrane having relatively large pores. The use of such a membrane: (a) allows the membrane to be protected from physical damage by covering it with a perforate structure; (b) significantly reduces bandspreading across the membrane reagent addition device; (c) reduces the pressure drop across the membrane reagent addition device; and (d) still allows for the permeation of an effective amount of the reagent into the carrier. The reagent is preferably pressurized to minimize leakage of carrier across the membrane and the reagent can be self-pressurized by essentially completely filling the reagent reservoir of the invention with reagent and then hermetically sealing the reservoir.

Abstract: Esterification of aromatic dicarboxylic acids with cyclic alkylene carbonates in the presence of organic compounds containing at least one six-membered aromatic nitrogen-containing heterocyclic moiety.

Abstract: The invention is a process for the preparation of a carbon dioxide oxirane copolymer wherein the process comprises contacting carbon dioxide with an oxirane in the presence of (1) an organic coordination compound and (2) a catalytic amount of a double metal cyanide complex under conditions such that an oxirane carbon dioxide copolymer is prepared.

Abstract: Alternating copolyestercarbonate resins having repeating units of the formula: ##STR1## wherein R.sup.1 is para-phenylene; each R is independently an aromatic hydrocarbylene or inertly substituted aromatic hydrocarbylene, e.g., ##STR2## and x is a number from 0.05 to 0.65 exhibit physical properties such as heat resistance, clarity and impact strength that are superior to the comparable properties of corresponding random copolymers. Such resins are useful for making transparent tough films and molded articles having high heat resistance.

Abstract: Linear polyesters are produced by esterification of aromatic dicarboxylic acids with cyclic alkylene carbonates in the presence of organic compounds containing at least one six-membered aromatic nitrogen-containing heterocyclic moiety followed by polycondensation of the resulting low molecular weight ester.

Abstract: Alternating copolyestercarbonate resins having repeating units of the formula: ##STR1## wherein R.sup.1 is meta-phenylene and R is independently an aromatic hydrocarbylene or inertly substituted aromatic hydrocarbylene, e.g., ##STR2## exhibit physical properties such as heat resistance, clarity and impact strength that are superior to the comparable properties of corresponding random copolymers and exhibit physical properties such as impact strength and processability that are superior to the comparable properties of corresponding alternating copolyestercarbonates wherein R.sup.1 is para-phenylene. Such resins are useful for making transparent tough films and molded articles having high heat resistance.

Abstract: Alternating copolyestercarbonate resins having repeating units of the formula: ##STR1## wherein each R is independently an aromatic hydrocarbylene or inertly substituted aromatic hydrocarbylene, e.g., ##STR2## exhibit physical properties such as heat and impact resistance that are superior to the heat and impact resistance of corresponding random copolymers. Such resins are useful for making transparent tough films and molded articles having high heat resistance.