Browse Prior Art Database

Method for Forming an Inverted Trench

IP.com Disclosure Number: IPCOM000044419D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Nesbit, LA: AUTHOR [+2]

Abstract

A method is disclosed for forming an inverted trench structure on a substrate for the isolation of devices in high density integrated circuits. Figs. 1 through 4 illustrate a sequence of stages in the method for making such a structure. A layer of a fill material that can with stand low pressure chemical vapor deposition (LP CVD) temperatures is formed on a surface of a substrate 10. This fill material can be, for example, polysilicon. The thickness of this material must be equal to or greater than the desired depth of the inverted trench. This layer is then patterned using a reactive ion etching process to produce strips 12 of the fill material with vertical sidewalls. An insulating layer 14, such as a layer of SiO2 or Si3N4 material, is deposited by LP CVD techniques over the entire structure, as shown in Fig. 2.

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Method for Forming an Inverted Trench

A method is disclosed for forming an inverted trench structure on a substrate for the isolation of devices in high density integrated circuits. Figs. 1 through 4 illustrate a sequence of stages in the method for making such a structure. A layer of a fill material that can with stand low pressure chemical vapor deposition (LP CVD) temperatures is formed on a surface of a substrate 10. This fill material can be, for example, polysilicon. The thickness of this material must be equal to or greater than the desired depth of the inverted trench. This layer is then patterned using a reactive ion etching process to produce strips 12 of the fill material with vertical sidewalls. An insulating layer 14, such as a layer of SiO2 or Si3N4 material, is deposited by LP CVD techniques over the entire structure, as shown in Fig. 2. The thickness of insulating material 14 is selected to be equal to or slightly greater than the desired width of the inverted trenches. Then the structure of Fig. 2 is planarized, through the reactive ion etching of a sufficient amount of insulating material which is equal to the thickness of the deposited insulating material. This results in the structure shown in Fig. 3. The planarization step may necessarily involve applying ("spinning on") a polyimide layer on the surface of the insulating layer so as to produce a planar polyimide surface. Plasma etching is then used to etch the polyimide and the insulating lay...