Method of removing refractory metal layers and of siliciding contact areas

#This Utility patent application claims priority to German Patent Application No. DE 10 2006 004 396.0 filed on Jan. 31, 2006, which is incorporated herein by reference.

#The switching speed and power consumption of semiconductor devices are closely linked to line and junction resistances within the semiconductor device. In order to reduce the line resistances, the connecting lines within the semiconductor device are provided from metals. In the case of field effect transistors, the junction resistance between the source/drain regions formed within a monocrystalline semiconductor substrate and a metallized contact structure that bears on the semiconductor substrate and connects the source/drain region to connecting lines formed in a metallization level above the semiconductor substrate remains critical. In order to reduce the junction resistance, the metal silicide is formed along the junction areas between the silicon substrate and the contact structure, the electrical resistance of said metal silicide being lower than that of a silicon/metal junction.

#A suitable metal silicide is cobalt silicide. For the purpose of siliciding (silicidation), a cobalt layer is applied to the silicon substrate and subjected to heat treatment at a silicidation temperature of approximately 550 degrees Celsius. Sections of the cobalt layer that adjoin the silicon substrate react with the silicon of the silicon substrate to form cobalt monosilicide. Unreacted sections of the cobalt layer are removed.

#The accompanying drawings are included to provide a further understanding of the present invention and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the present invention and together with the description serve to explain the principles of the invention. Other embodiments of the present invention and many of the intended advantages of the present invention will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.

#FIG. 1 illustrates a cross section through a semiconductor substrate with silicon and metal surfaces after the deposition of the refractory metal and an oxidation protection layer in the course of a processing according to an embodiment of the invention.

#FIG. 2 illustrates a cross section through a semiconductor substrate with silicon and metal surfaces after siliciding in the course of a processing according to the embodiment of FIG. 1.

#In the following Detailed Description, reference is made to the accompanying drawings, which form a part hereof, and in which is illustrated by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” “leading,” “trailing,” etc., is used with reference to the orientation of the Figure(s) being described. Because components of embodiments of the present invention can be positioned in a number of different orientations, the directional terminology is used for purposes of illustration and is in no way limiting. It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

#Embodiments of the invention relate to methods of removing a deposition layer including or composed of a low-density refractory metal in the course of fabricating a semiconductor device, in which sections of the deposition layer are removed by the action of a process liquid and a method of forming a metal silicide on a substrate surface of a substrate.

#An embodiment of the invention is related to the removal of, for instance, a deposition layer including or composed of a low-density refractory metal and deposited by means of cathode beam sputtering, vapor deposition (CVD) or ALD (atomic layer deposition), said layer being applied to a substrate in the course of fabricating a semiconductor device. The deposition layer is removed by the action of a process liquid, wherein ozone-enriched sulfuric acid (sulfuric acid ozone mixture, SOM solution) is used as process liquid.