Browse Prior Art Database

Metal Mask Etch End-Point Detection Diagnostic

IP.com Disclosure Number: IPCOM000036437D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 2 page(s) / 74K

Publishing Venue

IBM

Related People

Berasi, PH: AUTHOR [+4]

Abstract

A visual diagnostic process is described in this article which permits monitoring both etch end-point and etch field uniformity during the etching of composite metal structures used in the production of screening masks.

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Metal Mask Etch End-Point Detection Diagnostic

A visual diagnostic process is described in this article which permits monitoring both etch end-point and etch field uniformity during the etching of composite metal structures used in the production of screening masks.

Composite metal structures, such as are employed in the production of screening masks, require controlled etching of the inner core. Due to the fact that the outer metal layer obscures the core from view, it is extremely difficult by existing optical means to optimize the point at which etching is complete. This is shown in Fig. 1, which identifies the outer layer 1 and the core 2. Simultaneous etching of the core metal from both sides produces cavities in the core which are defined by the features in the outer composite metal, which acts as a resist to etching.

(Image Omitted)

The disclosed process allows etch completion to be determined by the use of a series of graduated features located outside the active pattern area on one or both outer surfaces of the mask, as shown in Fig. 2. The graduated features (diagnostic control patterns) 3, 4, 5, 6 and 7 are constructed as a series of concentric circles in the diagnostic control site 8. The active pattern area is identified as 9. The nominal size of the inner circle of the diagnostic control feature must be equal to the thickness of the inner metal core 2 within the composite, the diagnostic control feature being etched essentially from two sides, with...