Abstract: An apparatus (20) for monitoring the trench formation process in a silicon wafer on a full in-situ and on-line basis. The apparatus includes two spectrometers (30A, 30B) for viewing the plasma used in the trench etching process at zero and normal angles of incidence with respect to the plane of the wafer, respectively. Both spectrometers are tuned to detect the radiation associated with a selected specie present in the plasma. Based on information contained in the output signals of the spectrometers, the depth D of the trench and the thickness Th and rate of deposition of the redeposited SiO.sub.2 layer are computed in real time. When the computed depth D matches a final depth of parameter, the trench formation process is terminated.

Abstract: A follow-up system for monitoring the etching process in RIE equipment. A spectrometer is used in an interferometric mode for accurate thickness measuring to produce high-resolution and reproducible patterns in a layer of etchable material formed on a substrate.

Abstract: A method of producing high-resolution and reproducible patterns, typically polysilicon ultra-fine lines. According to a preferred embodiment of the method, a layer of a standard radiation-sensitive resist is applied over a polysilicon layer formed on a substrate. The photoresist is delineated as is standard in conventional UV lithography equipment to produce a first resist pattern. The structure is then placed in reactive ion etching (RIE) equipment and the resist pattern is isotropically eroded to reduce overall dimensions. The etched thickness (dTH) is accurately measured by interferometric techniques, so that the corresponding lateral dimension reduction (dW) is continuously monitored. The etching is terminated when the appropriate lateral dimension reduction has been obtained to produce a second resist pattern of the desired final width (LWf). The second resist pattern (17a') is then anisotropically transferred to the underlying polysilicon layer by reactive ion etching.

Abstract: In a dry etching equipment, a variable gas mixture composition provides etch and ash simultaneously. For example, when a SiO.sub.2 /phospho silicate glass composite insulating layer with a respective thickness of about 300 and 600 nm masked by a patterned photoresist layer is to be etched, a CHF.sub.3 /O.sub.2 gas mixture may be used with the following steps:1. Dry etching the composite insulating layer in an RIE equipment by a plasma action in a gas mixture containing a fluorine compound and an oxidizer with a percentage of the oxidizer of about 10-20% to form a tapered hole having the desired slope in the top PSG insulating layer;2. Dry etching the composite layer in the gas mixture with a percentage of the oxidizer in the gas mixture of about 1-8% to transfer the desired slope from the PSG insulating layer to the bottom SiO.sub.2 insulating layer, wherein during this step the slope of the tapered hole in the PSG insulating layer has been modified; and then3.