Nippondenso Co., Ltd.

Denso Corporation

Yoshikazu Sakano

Kenji Kondo

Hajime Soga

Shoji Miura

Eiji Ishikawa

Atsushi Komura

Keiichi Kon

Tetsuhiko Sanbei

Yoshifumi Okabe

Mikimasa Suzuki

Yasuo Ishihara

Yuji Ichikawa

In a method for manufacturing a semiconductor device, first, a trench is formed on a semiconductor substrate by anisotropic etching, and a reaction product is produced and deposited on the inner wall of the trench during the anisotropic etching. Then, isotropic etching is performed to round a corner of a bottom portion of the trench without removing the reaction product. The isotropic etching can round the corner of the trench without etching the side wall of the trench that is covered by the reaction product.

Method of forming a trench with a rounded bottom in a semiconductor device

After performing an etching process with respect to one substrate, the substrate is taken out from an etching chamber. Then, a dummy substrate is disposed in the etching chamber and a cleaning process is performed. The cleaning process includes a cleaning step for etching reaction products produced during the etching process to be removed, a seasoning step for adjusting the atmosphere within the etching chamber and the temperature of the substrate, and a purge step for removing suspended foreign materials without generating plasma. By performing the cleaning process, the successive etching process can be performed without generating any black silicon on the substrate, thereby attaining a high production yield.

Dry etching method for semiconductor substrate

A process for dry etching a silicon substrate, in which a mask exposing a region of the surface of the silicon substrate is formed, and the exposed region is dry etched. The dry etching is performed with a gas mixture including chlorine or a chlorine-containing gas, an oxygen-containing gas, and a fluorine-containing gas in which a ratio of a flow rate of oxygen gas to a flow rate of chlorine gas, O.sub.2 /Cl.sub.2, is selected to be from 0.6 to 3. The gas mixture may also contain a fluorine-containing gas and helium. Preferably, the gas mixture excludes carbon-containing gases. The dry etching process allows for an increased etch rate, as well as a high etch selectivity compared to that of SiO.sub.2 gas. The trench formed in the substrate by this process can be made of a larger depth with high reproducibility and good configuration. The sidewall profile angle of the trench is maintained slightly tapered, with a sidewall profile angle of approximately 90 degrees. Also, by mixing HBr gas into the gas mixture, it is possible to better control the formation of the trench. Thus, this process makes it possible to form, in a silicon substrate, a regularly configured and very deep trench with high accuracy and high etch rate.

Dry etching process for semiconductor

A process for forming trenches on a surface of a semiconductor substrate by dry etching using a gas mixture. The gas mixture comprises; (1) an etchant gas comprising at least bromine which etches the semiconductor surface to form trenches, (2) a cleaning gas comprising a halogen which evaporates residue formed by the etching, and (3) a reactive gas, e.g. N.sub.2, capable of reacting with material formed during the etching and capable of controlling the inclination of the trenches.

A process for forming deep trenches on a surface of a semiconductor substrate by forming a mask on the surface of the semiconductor, which prescribes the position of the trenches; and then dry etching the semiconductor surface using a gas mixture comprising (1) an etchant, bromine containing, gas which etches the semiconductor surface to form trenches, (2) a cleaning, halogen containing, gas which evaporates the residue formed by the etching; and (3) a reactive gas capable of reacting with material formed during the etching and capable of decreasing the wastage of the mask by the etchant gas.

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Obu, Japan

Yoshikazu Sakano