| Etching method, etching apparatus, and method for manufacturing semiconductor device -> Monitor Keywords |
|
|
 
Etching method, etching apparatus, and method for manufacturing semiconductor deviceRelated Patent Categories: Semiconductor Device Manufacturing: Process, Chemical Etching, Vapor Phase Etching (i.e., Dry Etching)Etching method, etching apparatus, and method for manufacturing semiconductor device description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060009039, Etching method, etching apparatus, and method for manufacturing semiconductor device. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for removing, by wet etching, a compound containing a metal such as hafnium and silicon, and a method for manufacturing a semiconductor device using the same. BACKGROUND ART [0002] In recent years, it has been proposed in the art to use a high dielectric constant material (hereinafter referred to as a "high-k material") in the gate insulating film of a field-effect transistor in order to prevent the decrease in the driving current while suppressing the increase in the gate current. Specifically, it has been proposed in the art to use hafnium oxide (HfO.sub.2: relative dielectric constant .epsilon.=30), zirconium oxide (ZrO.sub.2: relative dielectric constant .epsilon.=25), or the like, as the material of the gate insulating film so as to maintain a desired thickness of the gate insulating film, thereby reducing the leak current (see, for example, Japanese Laid-Open Patent Publication No. 2000-49349). [0003] When hafnium oxide, for example, is used as the material of the gate insulating film, a silicate (hafnium silicon oxide) is formed at the interface between the silicon substrate and the gate insulating film. Specifically, when a heat treatment is performed after a gate insulating film made of a high-k material such as hafnium oxide or zirconium oxide is formed on a silicon substrate, the gate insulating film reacts with the underlying silicon substrate, whereby an insufficiently-oxidized silicate, which is a compound between the material of the gate insulating film and silicon, is formed near the surface of the silicon substrate. Where a hafnium oxide film is used as the gate insulating film, insufficiently-oxidized hafnium silicon oxide is formed as the silicate. Moreover, where a zirconium oxide film is used as the gate insulating film, insufficiently-oxidized zirconium silicon oxide is formed as the silicate. [0004] Wet etching using an aqueous hydrogen fluoride solution is suitable for etching away a hafnium oxide film, a zirconium oxide film, or the like, as with a silicon oxide film. This is because an aqueous hydrogen fluoride solution does not substantially etch the silicon substrate. [0005] However, it is difficult to remove a silicate such as hafnium silicon oxide or zirconium silicon oxide by a wet etching method using hydrogen fluoride, or the like. Specifically, the etching rate of wet etching using hydrogen fluoride, or the like, for hafnium silicon oxide or zirconium silicon oxide is about 1/10 to 1/30 that for hafnium oxide or zirconium oxide. Thus, when an insulative metal oxide film such as a hafnium oxide film is used as the gate insulating film, an insufficiently-oxidized silicate layer such as a hafnium silicon oxide film is formed at the interface between the silicon substrate and the gate insulating film, and it is difficult to remove the silicate layer by a wet etching method using hydrogen fluoride, or the like. As a result, the unremoved silicate remains on the surface of the silicon substrate when forming the gate electrode structure. Thus, a plurality of minute field-effect transistors, which are supposed to be electrically separated from one another, are electrically shorted with one another. Moreover, through a heat treatment step after the formation of the gate electrode structure, the silicate remaining on the surface of the silicon substrate is implanted into the silicon substrate as an impurity, thereby forming a level due to the impurity, which adversely influences the semiconductor substrate. DISCLOSURE OF THE INVENTION [0006] In view of the above, it is an object of the present invention to make it possible to reliably remove, by wet etching, a compound containing at least a metal and silicon, specifically, an insufficiently-oxidized silicate containing a hafnium metal, a zirconium metal, or the like. [0007] In order to achieve the object set forth above, an etching method of the present invention includes: a first step of oxidizing a compound containing at least a metal and silicon; and a second step of removing the oxidized compound by wet etching. [0008] With the etching method of the present invention an insufficiently-oxidized compound containing a metal and silicon is oxidized, whereby the composition of the compound can be brought closer to the stoichiometric composition of the metal oxide. Therefore, the insufficiently-oxidized compound, which is normally insoluble in an etching liquid (hereinafter referred to as an "etchant") such as an aqueous hydrogen fluoride solution, is oxidized, and becomes more soluble in the etchant, whereby it is possible to reliably remove the compound by wet etching. [0009] In the etching method of the present invention, if the metal to be etched is hafnium or zirconium, the composition of the oxidized compound is closer to the stoichiometric composition of hafnium oxide (HfO.sub.2) or zirconium oxide (ZrO.sub.2), whereby it is possible to reliably remove the oxidized compound by wet etching using hydrogen fluoride, or the like. [0010] In the etching method of the present invention, if the compound to be etched is an oxygen-containing (insufficiently-oxidized) silicate compound, the composition of the silicate compound is brought even closer to the stoichiometric composition of the metal oxide by the oxidization, whereby it is possible to reliably remove the oxidized silicate compound by wet etching using hydrogen fluoride, or the like. [0011] In the etching method of the present invention, if the compound to be etched is an intermetallic compound (e.g., a silicide), the composition of the oxidized intermetallic compound is brought closer to the stoichiometric composition of the metal oxide; whereby it is possible to reliably remove the oxidized intermetallic compound by wet etching using hydrogen fluoride, or the like. [0012] In the etching method of the present invention, it is preferred that the first step includes a step of irradiating the compound with ultraviolet light in an oxygen-containing atmosphere. [0013] In this way, ozone is generated by the ultraviolet light irradiation, whereby the compound can reliably be oxidized by the ozone, starting from its surface side. [0014] Moreover, in this case, it is preferred that the ultraviolet light irradiation is performed while supplying a nitrogen gas into the atmosphere. [0015] In this way, it is possible to suppress the attenuation of ultraviolet light in the atmosphere, whereby ozone can reliably be generated by the ultraviolet light irradiation. Moreover, similar effects can be obtained by using another inert gas, instead of a nitrogen gas. [0016] In the etching method of the present invention, it is preferred that a step of irradiating the compound with ultraviolet light while an oxygen-containing liquid (e.g., water) is attached to a surface of the compound is included. [0017] In this way, ozone is generated by the ultraviolet light irradiation, whereby the compound can reliably be oxidized by the ozone, starting from its surface side. [0018] In the etching method of the present invention, it is preferred that the first step includes a step of exposing the compound to an ozone-containing solution. [0019] In this way, the compound can reliably be oxidized, starting from its surface side. [0020] In the etching method of the present invention, it is preferred that a solution containing fluorine and hydrogen is used as an etchant in the second step. [0021] In this way, it is possible to reliably remove the oxidized compound by wet etching using a solution containing fluorine and hydrogen, specifically, an aqueous hydrogen fluoride solution. Continue reading about Etching method, etching apparatus, and method for manufacturing semiconductor device... Full patent description for Etching method, etching apparatus, and method for manufacturing semiconductor device Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Etching method, etching apparatus, and method for manufacturing semiconductor device patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Etching method, etching apparatus, and method for manufacturing semiconductor device or other areas of interest. ### Previous Patent Application: Processing for overcoming extreme topography Next Patent Application: Method for manufacturing semiconductor device Industry Class: Semiconductor device manufacturing: process ### FreshPatents.com Support Thank you for viewing the Etching method, etching apparatus, and method for manufacturing semiconductor device patent info. IP-related news and info Results in 0.16404 seconds Other interesting Feshpatents.com categories: Medical: Surgery , Surgery(2) , Surgery(3) , Drug , Drug(2) , Prosthesis , Dentistry 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
