Northern Telecom Limited

Thomas Abraham

Robert E Theriault

In a method for planarizing an insulating layer, the height of steps in a layer of insulating material are reduced while tapering side walls of the steps by forming a layer of sacrificial material between the steps and etching the insulating material and the sacrificial material in a low pressure plasma comprising reactive ions and facetting ions. This method combines many of the advantages of Resist Etch Back (REB) and argon facetting techniques while reducing the deleterious effects of macroloading and microloading.

Method for planarizing an insulating layer

A plasma etching technique for producing tapered side walls on the desired Aluminum conductor pattern is described. This involves forming a resist pattern on the Aluminum layer of a wafer and carrying out a first etching step using Cl.sub.2, BCl.sub.3 and CF.sub.4 at predetermined flow rates and low pressure until all the exposed Aluminum is removed. At the end of this step the Aluminum side walls are virtually vertical and facets are present on the resist. A second etching step is carried out under essentially the same conditions as before except that the Cl.sub.2 is reduced. During this etching step the facets on the resist are propagated laterally while the Aluminum side walls become tapered. According to modifications a rounded or jogged configuration can be obtained on the side walls but these too are considered generally tapered in nature as they progress from a wider base to a narrower peak.

Method of etching aluminum alloys in semi-conductor wafers

In a silicon integrated circuit manufacturing process a layer of polysilicon is ion implanted with an n-type dopant and etched through a mask with a fluorine:chlorine mixture. The etchant undercuts at the mask to an extent dependent on the ratio of chlorine:fluorine and on the dopant level. By appropriately selecting that ratio and dopant level, polysilicon islands having a rounded profile can be achieved, this being most efficacious for subsequent deposition onto the polysilicon.

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Kanata, Canada

Thomas Abraham