Backside coating for mems wafer and its making process

Abstract

The invention provides a micro-electromechanical transparent substrate and manufacturing process thereof. The micro-electromechanical transparent substrate comprises a micro-electromechanical system positioned on a first side. The manufacture method includes following steps: forming an opaque layer on a second side of the transparent substrate opposite to the first one, the opaque layer including a first material which can be removed by a release process of the micro-electromechanical system; and forming a second layer on the opaque layer, the second layer containing a second material to prevent a front-end mechanical line from being contaminated by the first material during manufacturing lines on the front end. The micro-electromechanical transparent substrate and manufacturing process of the invention can protect the back side of the substrate during treatment of the front end lines of the opaque layer and the second layer and prevent contamination of processing equipment by the first material of the opaque layer, thus increasing the production count in a preventive maintenance operation period, obviating extra TiOX removal step in prior front-end line treatment, suppressing the negative influences on the circulation time and the production force due to the removal of TiOX and reducing the cost.

Description

technical field [0001] The present invention relates to semiconductor fabrication, and more particularly to fabrication of substrates including micro electromechanical systems (MEMS). Background technique [0002] The projection display industry has grown explosively in recent years. Until a few years ago, this projection display system was mainly used in cathode ray tube (CRT) or active liquid crystal display (LCD) technology. However, the application of these traditional displays will be affected. Many limitations, including limited performance or spectrum, LCD or CRT-based systems are not suitable for high-brightness applications, and will also encounter problems such as uniformity and stability in large-scale applications. [0003] In 1996, Texas Instruments (TI) proposed a new microelectromechanical system (microelectromechanical system, MEMS) high-efficiency projection technology to solve the above problems. This technology called digital light processing (DLP) mainly ...

AI Technical Summary

Problems solved by technology

[0009] However, the MEMS process still has many serious problems. First, although the Ti / OX backside coating 104 on the back side can solve the transmission problem, it requires another process to remove the Ti / OX, so this technology includes optical Coating, backside etching, dry photoresist stripping, and wet post-cleaning, this creates a heavy load on equipment for backside etch productivity, increasing cycle time and wasting productivity, and in this case, the removal of Ti / OX Except for the front end of line (FEOL) process, preventive maintenance (PM) must be done after processing 24 pieces to prevent the decrease of etching rate and pollution, which will increase the burden on production

[0010] Furthermore, the backside of the wafer may also be damaged during the etching process (damaged surface 100b such as Figure 1C and Figure 1D shown), in some etching installations, the wafer 100 will be larger than the platform (not shown), so the outer ring region on the back of the wafer 100 will be exposed to the etching gas during etching, making it difficult to damage the back of the wafer 100b avoid

[0011] Damage to the backside 100b of the substrate 100 can cause transmission errors during the post-Ti / OX removal process, which can lead to scrapping of wafers in the fabrication line (i.e. if light penetration has been compromised)

[0012] Another disadvantage of the above-mentioned process is that the backside Ti / OX coating 104 needs to be removed during the FEOL process to make the wafer become transparent again. However, when performing the wafer acceptance test (wafer acceptance test, WAT), The infrared sensor must detect the wafer plane before transferring the wafer to the WAT station, but because the infrared sensor cannot perform the detection action after the Ti / OX layer is removed, the wafer 100 (transparent at this time) is Cannot be transmitted, so the transparent base cannot be used as WAT

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