Method for precisely controlled masked anodization

a technology of masking and anodization, which is applied in the direction of coatings, surface reaction electrolytic coatings, electrolytic coatings, etc., can solve the problem of self-limitation of the anodization process, and achieve the effect of improving and cost-efficien

US20120132529A1Inactive Publication Date: 2012-05-31INTERUNIVERSITAIR MICRO ELECTRONICS CENT (IMEC VZW) +1
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Patent Information

Authority / Receiving Office
US · United States
Current Assignee / Owner
Publication Date
2012-05-31
Estimated Expiration
Not applicable · inactive patent

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Abstract

The present invention is related to a method for masked anodization of an anodizable layer on a substrate, for example an aluminum layer present on a sacrificial layer, wherein the sacrificial layer needs to be removed from a cavity comprising a Micro or Nano Electromechanical System (MEMS or NEMS). Anodization of an Al layer leads to the formation of elongate pores, through which the sacrificial layer can be removed. According to the method of the invention, the anodization of the Al layer is done with the help of a first mask which defines the area to be anodized, and a second mask which defines a second area to be anodized, said second area surrounding the first area. Anodization of the areas defined by the first and second mask leads to the formation of an anodized structure in the form of a closed ring around the first area, which forms a barrier against unwanted lateral anodization in the first area.
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Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61 / 418,194, filed Nov. 30, 2010, the disclosure of which is hereby expressly incorporated by reference in its entirety and is hereby expressly made a portion of this application.FIELD OF THE INVENTION

[0002] Methods for precisely controlling a masked anodization process are provided. The preferred embodiments are further related to manufacturing semiconductor devices, especially to methods of encapsulation and to such devices. More specifically they may relate to zero-Level or wafer level packaging of semiconductor devices. More particularly, the preferred embodiments relate to Nano- and / or Micro-Electro-Mechanical Systems (NEMS and / or MEMS) and to processes of encapsulating (or packaging) said systems.BACKGROUND OF THE INVENTION

[0003] Creating patterns of a dielectric or porous material within a conductive thin film by means of masked anodization ...

Examples

examples

[0103]By way of illustration, preferred embodiments not being limited thereto, a number of further particular examples are discussed below, illustrating features and advantages of preferred embodiments.

[0104]In a first particular example, anodization of a 1 μm-thick Al layer (deposited by sputtering on top of a silicon oxide layer on 200 mm Si wafer) has been performed using a photoresist mask not including the border line structure resulting in a large unwanted extension of the anodization region width from 160 μm up to 800 μm as shown in FIG. 2. The anodization process is performed in a Teflon-based chamber housing a sulfuric acid-based electrolyte. The anodization temperature and voltage used here are within the range of 20-30° C. and 10-20V respectively. By performing the same anodization process of an Al layer using a photoresist mask defining a border line 23 (ring) surrounding a plurality of other structures 21 as shown in FIG. 6, the anodization region width has been well co...