Method and apparatus for an integrated laser beam scanner using a carrier substrate

Abstract

An solid state scanning system having a single crystal silicon deflection mirror and scanning mirror is integrated with a light source. Separation of the micro-electro-mechanical systems and light emitters on separate substrates allows the use of flip-chip and solder bump bonding techniques for mounting of the light sources. The separate substrates are subsequently full wafer bonded together to create an integrated solid state scanning system.

Description

CROSS-REFERENCE TO RELATED APPLICATIONSThe present invention is related to "METHOD AND APPARATUS FOR AN INTEGRATED LASER BEAM SCANNER" by Floyd, Sun and Kubby (Attorney Docket No. D / 98706). Ser. No. 09 / 201738, filed on the same day and assigned to the same assignee which is hereby incorporated by reference in its entirety.BACKGROUND AND SUMMARY OF INVENTIONThe present invention relates generally to the field of laser beam scanning systems, and more particularly to micro-electro-mechanical systems (MEMS) for laser beam scanning. Miniature laser beam scanning systems are important for applications such as barcode scanning, machine vision and, most importantly, xerographic printing. The use of MEMS to replace standard raster output scanning (ROS) in xerographic print engines allows simplification of printing systems by eliminating macroscopic mechanical components and replacing them with large arrays of scanning elements. Advanced computation and control algorithms are used in managing...

AI Technical Summary

Benefits of technology

The present invention relates generally to the field of laser beam scanning systems, and more particularly to micro-electro-mechanical systems (MEMS) for laser beam scanning. Miniature laser beam scanning systems are important for applications such as barcode scanning, machine vision and, most importantly, xerographic printing. The use of MEMS to replace standard raster output scanning (ROS) in xerographic print engines allows simplification of printing systems by eliminating macroscopic mechanical components and replacing them with large arrays of scanning elements. Advanced computation and control algorithms are used in managing the large arrays of scanning elements. Such MEMS based printing systems are entirely solid state, reducing complexity, and allowing increased functionality, including compensation of errors or failures in the scanner elements.

Using solder bump bonding methods, completed and tested laser diodes are bonded to a glass or a silicon carrier substrate. The carrier substrate is aligned and bonded to a Si or SOI wafer containing the MEMS layers. Bonding of the lasers to a carrier substrate completely partitions the bonding process from the MEMS. This complete partition eliminates possible conflicts between the conditions needed for solder bump bonding, such as the use of solder flux, and preserves the integrity of the MEMS layers.

The substrates are heated in a non-oxidizing environment to join the two substrates. High surface tension of the solder aligns the wettable metal bonding pads on each substrate with each other. The ability of the reflowed solder to self-align the substrates because of surface tension simplifies assembly.

The use of the SCS layer of a SOI wafer, rather than a polysilicon film provides for the introduction of very flat and smooth mirrors and high reliability torsion bars. The device is scalable to arrays of lasers and scanning mirrors.

Integration of the scanner and light source eliminates the need for external, manual alignment of light sources and scanning mirrors. Simplified post-processing steps such as interconnect metallization can be realized because the use of an etched recess results in nearly planar surfaces. In addition, pick and place technologies used for multi-chip module assembly can be adapted for wafer scale assembly and bonding of light sources to the carrier substrate.

Problems solved by technology

However, current techniques do not allow for wafer-scale integration of the light-emitter and MEMS device.

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