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Method for an EA modulator for EUV wavelengths using the quantum confined stark effect

IP.com Disclosure Number: IPCOM000084997D
Publication Date: 2005-Mar-02
Document File: 3 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an electroabsorption (EA) modulator for extreme ultraviolet (EUV) wavelengths using the quantum confined stark effect (QCSE). Benefits include improved functionality and improved performance.

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Method for an EA modulator for EUV wavelengths using the quantum confined stark effect

Disclosed is a method for an electroabsorption (EA) modulator for extreme ultraviolet (EUV) wavelengths using the quantum confined stark effect (QCSE). Benefits include improved functionality and improved performance.

Background

              Precise light modulation is difficult in EUV systems. Conventionally, the light source is modulated or mechanically shuttered. No solid-state solution exists.

      In a conventional quantum well system, the applied electric field has an effect on optical absorption. The absorption peak red-shifts (shifts to longer wavelength) with an increase in the electric field.

General description

              The disclosed method uses the quantum confined stark effect to change the absorption of silicon in an applied field and enable an EA modulator for EUV wavelengths. The method can be used with mask-writing applications.

      An electrical field is applied to a multiple quantum well, dot, or wire structure to induce a change in EUV absorption. The device works in transverse or longitudinal transmission to the applied electrical field. The quantum wells are made from silicon, which has an abrupt change in absorption close to 13.5 nm. The spacing material must have a high EUV transmission and cannot not have an absorption edge close to 13.5 nm, which reduces the contrast of the quantum wells in the EUV modulator.

      The thickness of conventional quantum wells for EA modulators is in the range of 5 to 20 monolayers. For example, the thickness can be approximately 1.4 nm to 6.1 nm. The optimum value is dependant on the excitonic confinement within the well.

Advantages

              The disclosed method provides advantages, including:
•             Improved functionality due to providing a solid state/electronic approach to modulating EUV light
•             Improved performance due to enabling fast modulation speeds

Detailed description

      The disclosed method is an EA modulator that is comprised of a set of quantum wells, wires, or dots across which an electric field is applied. EUV light passes through the structure and is attenuated by different amounts according to the applied voltage (see Figures 1 and 2).

      The disclosed method can be verified using a sample implementation. The absorption edge of silicon is very close to the 13.5-nm wavelength. The edge is at a slightly shorter wavelength, which is relevant to EUV lithography. T...