| 摘要 |
PURPOSE:To widen the margin of etchback as well as to prevent the thinning of a field insulating film formed on the protruded parts of an Si substrate by a method wherein a second insulating film, whose etching rate is slow, is formed on the lower part of an insulating film at the time of the etchback. CONSTITUTION:A P<+> type layer 22, which is to become a channel stopper, is formed in recessed parts formed on a P type Si substrate 21, and after that, an SIO2 film 23 is formed by a CVD method. SiO2 films 24 formed by a CVD method are selectively formed on the upper parts of the recessed parts of the surface of the film 23 as a spacer respectively by a photo etching method. After then, after a PSG film 25 containing phosphorous was formed as a fluidity film, the film 25 is made to drift by performing a thermal treatment and the surface of the substrate 21 is flattened. N<+> type ions are implanted by an ion implantation method, for example, and a thermal treatment is performed in an atmosphere of N2 for 20min at the temperature of 1,000 deg.C. A compound 26 of SiO2 and N2 is formed on the upper part of the SiO2 film 23 in the recessed parts of the Si substrate 21 and on the lower part of the SiO2 film 23 in the protruded parts of the Si substrate 21. After this, an etching is performed until the surface of the compound 26 is made to expose by an RIE method, wherein Freon gas is used. After that, the compound 26 is removed using an etching liquid and an MOSFET is formed according to the ordinary process. |
