Shadow mask deposition

Details Shadow mask deposition Shadow mask deposition

1997-02-24

2001-08-14

Beck, Shrive (Department: 1762)

Coating processes

Nonuniform coating

Mask or stencil utilized

C427S058000, C427S096400, C427S307000, C427S309000, C118S504000, C430S022000, C438S944000

Reexamination Certificate

active

06274198

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the deposition of material on a substrate using a shadow mask.
BACKGROUND OF THE INVENTION
Many types of electronic components and circuits require a nonplanar substrate surface. For example, in the field of optoelectronics, channels are often etched on the surface of a silicon substrate in order to provide mounting of optical components or to increase coupling efficiency between the components. (See, e.g., U.S. Patent Application of Anigbo et al, Ser. No. 60/009116, filed Dec. 22, 1995, which is incorporated by reference herein.) In many cases, these nonplanar surfaces require a metal coating which, for example, acts as a reflecting layer. Since these metal layers are usually patterned, a mask should be employed on the substrate surface. Typically, the mask employed for patterning metal on a planar substrate surface is a photoresist material. However, when the surface is nonplanar, difficulties can be encountered in depositing and cleaning off the photoresist material.
In the fabrication of planar integrated circuits, it is known in general to employ masks made of metal (e.g., molybdenum) on the substrate, a technology usually referred to as shadow masking. This technique has lost favor in the industry due to the inability to achieve accurate registration.
It is desirable to provide a shadow mask technique which can be used for depositing metal on a nonplanar or planar substrate and achieve accurate registration.
It is known in general to position two components by forming conical bores in the facing surfaces and provide spheres in the bores. (See U.S. Pat. No. 4,070,120 issued to Bald et al.) It is also known to position silicon IC chips onto silicon or ceramic substrates by etching V-grooves in the substrate which correspond to contact pads on the chip having spheroidal solder or gold so that the solder or gold will be located within a corresponding groove. (See U.S. Pat. No. 3,379,937 issued to Shepherd and U.S. Pat. No. 4,288,808 issued to Hantusch.) It has been further suggested to position a ceramic chip carrier or a silicon chip on a printed circuit board by forming indentations in both the chip and substrate and employing spherical bodies in the indentations. The indentations can be pyramid shaped. (See, U.S. Pat. No. 3,184,831 issued to Siebertz, and U.S. Pat. No. 4,565,314 issued to Scholz.)
The art does not appear to have addressed the problem of how to deposit a metal onto a nonplanar or planar substrate by means of shadow masking to achieve accurate registration.
SUMMARY OF THE INVENTION
The invention is a method of depositing a material on a substrate including the step of providing a semiconductor mask with an aperture for defining the area of the substrate to be covered by the material. The mask further comprises a plurality of etched features in a major surface of the mask, which features are pyramidal. A major surface of the substrate also includes pyramidal shaped features. The mask is positioned so that the major surfaces are facing one another with spheres located in the features of one of the major surfaces, and the mask is moved until the spheres are positioned in corresponding features in both the mask and the substrate so that the mask is aligned with the substrate. The material is then deposited onto the substrate through the aperture.


REFERENCES:
patent: 4256532 (1981-03-01), Magdo et al.
patent: 4271577 (1981-06-01), Kosugi
patent: 4565314 (1986-01-01), Scholz
patent: 4625561 (1986-12-01), Mikkor
patent: 5120421 (1992-06-01), Glass et al.

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