Abstract: A pipe cleaning device has a handle, a center rod, a center rod sealing plate, and a scraper assembly. The center rod has a central hollow space having one end connected to the handle and the scraper assembly mounted on the other end. The center rod sealing plate is a three-plate structure for sealing off the pipe opening. The center rod sealing plate has a central hole for the insertion of the center rod. The three-plate structure of the center rod sealing plate serves to increase the ease of disassembling and maintenance. The scraper assembly includes an upper scraper and a lower scraper, wherein the lower scraper has additional scraping knives on its blades to facilitate the scraping of blocking material inside the pipe. Moreover, the scrapers do not block off gas flow inside the pipe completely, so the pump can still pump exhaust gases out even when the scraper assembly is in use.

Abstract: A structural configuration for a ceramic ring for guiding a semiconductor wafer down to the lower electrode of a dry etcher having upper and lower electrodes. The ceramic ring includes a base ring, a wall ring rising perpendicular to one surface of the base ring, and more than ten projections located on the top edge surface of the wall ring. Each of the projections includes a first and a second triangular surface, each at one end of the prismatic body and rising from the top edge surface of the wall ring. An inner sloped surface rises from-the top edge surface of the wall ring and an outer sloped surface rises from the top edge surface of the wall ring. First and second oblique sloped surfaces rise from the top edge surface of the wall ring, connecting the first and second triangular surfaces to the inner sloped surface, respectively.