Browse Prior Art Database

Variably Doped Layers for Variable Etching and/or Anodization Rate

IP.com Disclosure Number: IPCOM000084350D
Original Publication Date: 1975-Oct-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Romankiw, LT: AUTHOR

Abstract

A concentration profile is formed through the thickness of a metal or a dielectric, to obtain a progressively increasing etching or anodization rate from the top to the bottom of a layer.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Variably Doped Layers for Variable Etching and/or Anodization Rate

A concentration profile is formed through the thickness of a metal or a dielectric, to obtain a progressively increasing etching or anodization rate from the top to the bottom of a layer.

The concentration profile is obtained by either (a) phasing in an element during evaporation which makes the layer progressively less soluble by the etchant from the bottom to the top of the layer (progressively easier to anodize or etch from top to bottom); (b) diffusing from the top into the metal or dielectric an element which accomplishes the same result; (c) increasing by phasing in during evaporation the concentration of Ta (or other dopants listed below) in Al, so that the Ta content in the top of the layer is higher than at the bottom, and therefore, the anodizing rate increases from top to bottom of the layer; (d) depletion of O(2) in the SiO(2) or glass film during deposition of the film, so that the SiO(2) or glass toward the top of the layer is oxygen deficient and, therefore, slower to etch; or
(e) phasing in of N to form mixed Si(x)O(y)N(z) which is slower to etch.

Fig. 1 shows a substrate 10 having a deposited layer 11 on it composed of Al doped with Si, Ta, Hf, Ti, Nb or the like. The highest concentration of the dopant is at the top surface 12 of layer 11 and the lowest concentration of dopant is at the lower surface 14 of layer 11.

Fig. 2 shows substrate 20 coated with an Al layer 21 coated with layer 22 of Si, Ta, H...