CS254170B1 - Straight sign for direct electron lithography - Google Patents

Abstract

The purpose is to realize an alignment mark for direct electron lithography, during the preparation of which there is no damage to the resist layer or substrate, without high material costs and with a simple preparation method. The stated purpose is achieved by using an adhesive layer of chromium or a chromium-nickel alloy and a functional layer of antimony for the preparation of the alignment mark. A thin layer of chromium or a chromium-nickel alloy is deposited on the substrate by advantageous thermal evaporation and then a layer of antimony is deposited in the same vacuum cycle. The alignment mark can find wide application in technological processes for the production of microelectronic circuits with very high integration density using direct electron lithography.

Description

The invention relates to adjustment features for direct electron lithography.

In the process of direct electron lithography, one of the important factors influencing the accuracy of adjustment and mutual concealing of individual technological levels is the quality of adjustment features. By quality we mean the dimensional and shape, the accuracy of the given configuration of the structures located at the designated locations and the good detectable signal obtained after the electron beam has been rerouted through this structure. Until now, heavy metals such as tungsten have been used for the preparation of such features, which at the same time have a high atomic mass and thus a significantly different coefficient of reflection of electrons from the substrate, usually of silicon, which makes it possible to obtain a good signal from such labels. Such material are tantalum, tungsten, platinum, niobium. The disadvantage of these materials is that the deposition of the resist layer or substrate is often caused by deposition, whether by electron evaporator or various types of sputtering devices, whether by contact with plasma, electrons or thermal effects. In many technological processes for forming microelectronic structures, it is not necessary for the adjustment features to be made of refractory metal, but it is sufficient that the material has sufficient atomic mass.

These drawbacks are substantially eliminated by the feature for direct electron beam lithography of the present invention, which feature is that the feature is comprised of a chromium adhesion layer or a chromium-nickel alloy and a functional antimony layer. The adjustment feature is deposited advantageously by thermal evaporation of the chromium or chromium nickel layers in the same vacuum cycle. The layer thickness of the chromium or chromium nickel is 5 to 100 nm, the layer thickness of the antimony is at least 300 nm.

The advantages of the invention are that

Claims (3)

OBJECT 1. A direct electron beam lithographic feature formed on a substrate, characterized in that it consists of an adhesive layer of chromium or a layer of chromium nickel alloy and a functional layer of antimony. 2. The indicia of item 1 is characterized by damage to the resist layer or substrate, and lift off technology is preferably used to form the deposited layers. The thermal vaporizer used to deposit the layers is, unlike the electron evaporator or sputtering device, the basic equipment for vacuum deposition devices. The use of antimony also finds difficult to access or strategically important materials such as tungsten, tantalum, niobium, gold, platinum. EXAMPLE 1 A silicon substrate with a layer of polymethyl methacrylate deposited and formed with a thickness of 1 micron is deposited by thermal evaporation with a 6 nm thick layer of chromium nickel and a 30 nm thick antimony layer in the same vacuum cycle. Then the backing layer of polymethyl methacrylate in acetone is dissolved, whereby the deposited layers are formed into the shape of a caliper. Ultrasound may be used to dissolve the polymethyl methacrylate layer. EXAMPLE 2 A galium-arsenide pad with a 1 micron thick layer of polymethyl methacrylate deposited and formed with a thermal evaporation deposited a 6 nm thick layer of chromium and a 500 nm thick layer of antimony in the same vacuum cycle. Then the backing layer of polymethyl methacrylate in acetone is dissolved, whereby the deposited layers are formed into the shape of a caliper. Ultrasound may be used to dissolve the polymethyl methacrylate layer. The invention can find use in most modern technological processes for the production of microelectronic circuits of very large integration using direct electron beam lithography. characterized in that the thickness of the chromium layer or the chromium-nickel alloy formed by the thermal evaporation is 5 to 100 nm. 3. The indicia of item 1, wherein the thickness of the antimony layer is at least 300 nm.