Browse Prior Art Database

Manufacturing Technology of Super Reflective LCoS Light Modulators

IP.com Disclosure Number: IPCOM000018766D
Publication Date: 2003-Aug-06
Document File: 3 page(s) / 67K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that increases reflectivity of light modulators by increasing the aperture ratio up to 100%.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 56% of the total text.

Manufacturing Technology of Super Reflective LCoS Light Modulators

Disclosed is a method that increases reflectivity of light modulators by increasing the aperture ratio up to 100%.

Background

Currently, the process uses aluminum (Al) as a reflective metal, because there exists a highly developed stage of dry etching technology for Al in microelectronics. However, the reflectivity of the best reflective Al films does not exceed ~91% for visible light with wavelength in the range of 4,000Å to 7,000 Å. As a result, about 9% of the light intensity is lost due to absorption in the Al film; this light energy heats up the silicon chip, creating a serious thermal issue when working with the LCoS light modulator. The LCoS light modulator requires artificial cooling for the chip with fen.

These light losses could be decreased to ~0.5% by depositing silver (Ag) in thin films, to be used as reflective micro mirrors (see Figure 1). However, the technology for Al film dry etching is not developed enough to be used in LCoS manufacturing (i.e. this technology is extremely expensive and has the potential of contaminating the silicon with Ag).

General Description

The main element of the disclosed method is a new wet etching process, designed to create silver micro mirrors; the size of each micro mirror is approximately 13 um. The etching solution (H3PO4: CH3COOH: HNO3) enables a resolution of approximately 1-2 um, which is acceptable for manufacturing light modulators with 100% aperture op...