Method for making a micromechanical device by removing a sacrificial layer with multiple sequential etchants

Abstract

An etching method, such as for forming a micromechanical device, is disclosed. One embodiment of the method is for releasing a micromechanical structure, comprising, providing a substrate; providing a sacrificial layer directly or indirectly on the substrate; providing one or more micromechanical structural layers on the sacrificial layer; performing a first etch to remove a portion of the sacrificial layer, the first etch comprising providing an etchant gas and energizing the etchant gas so as to allow the etchant gas to physically, or chemically and physically, remove the portion of the sacrificial layer; performing a second etch to remove additional sacrificial material in the sacrificial layer, the second etch comprising providing a gas that chemically but not physically etches the additional sacrificial material. Another embodiment of the method is for etching a silicon material on or within a substrate, comprising: performing a first etch to remove a portion of the silicon, the first etch comprising providing an etchant gas and energizing the etchant gas so as to allow the etchant gas to physically, or chemically and physically, remove the portion of silicon; performing a second etch to remove additional silicon, the second etch comprising providing an etchant gas that chemically but not physically etches the additional silicon.

1 . An apparatus comprising: 
 an etching chamber;    connected to the etching chamber, a first source of etchant capable of etching in a plasma state; and    connected to the etching chamber, a second source of etchant different from the first source of etchant and capable of etching in a non-plasma state.    
     
     
         2 . The apparatus of  claim 1 , further comprising an RF source.  
     
     
         3 . The apparatus of  claim 1 , further comprising a source of stiction treatment connected to the etching chamber.  
     
     
         4 . The apparatus of  claim 3 , wherein the stiction treatment source is a source of a chlorosilane.  
     
     
         5 . The apparatus of  claim 1 , further comprising a load lock selectively in fluid communication with the etching chamber.  
     
     
         6 . The apparatus of  claim 1 , wherein the chamber comprises two chambers, one chamber having the RF source with the first source of etchant connected thereto, a second chamber having the second source of etchant connected thereto.  
     
     
         7 . The apparatus of  claim 1 , wherein the first source of etchant is a source of a hydrocarbon, fluorocarbon or SF6 and the second source of etchant is a source of noble gas halide or interhalogen.  
     
     
         8 . The apparatus of  claim 7 , wherein the first source of etchant is a source of fluorocarbon and the second source of etchant is bromine trifluoride or xenon difluoride.  
     
     
         9 . The apparatus of  claim 7 , further comprising a source of at least one of Ar, O2, He and N2.  
     
     
         10 . The apparatus of  claim 1 , further comprising a recirculation line for selectively recirculating etchant gas.  
     
     
         11 . The apparatus of  claim 1 , wherein the etchants of the first and second sources are gases capable of etching silicon when released into the etching chamber, the gas from the second source capable of etching silicon in a non-plasma state.  
     
     
         12 . An apparatus comprising: 
 a first etching chamber;    connected to the first etching chamber, a source of a first etchant capable of etching in a plasma state; and    a second etching chamber;    connected to the second etching chamber, a source of a second etchant different from the first source of etchant and capable of etching in a non-plasma state.    
     
     
         13 . The apparatus of  claim 12 , wherein said first etching chamber comprises an RF source.  
     
     
         14 . The apparatus of  claim 12 , further comprising a source of stiction treatment.  
     
     
         15 . The apparatus of  claim 14 , wherein the stiction treatment source is a source of a chlorosilane.  
     
     
         16 . The apparatus of  claim 12 , further comprising a load lock.  
     
     
         17 . The apparatus of  claim 12 , wherein the first etchant is a hydrocarbon, fluorocarbon or SF6 and the second etchant is a noble gas halide or interhalogen.  
     
     
         18 . The apparatus of  claim 17 , wherein the first etchant is a source of fluorocarbon and the second etchant is bromine trifluoride or xenon difluoride.  
     
     
         19 . The apparatus of  claim 17 , further comprising a source of at least one of Ar, O2, He and N2.  
     
     
         20 . The apparatus of  claim 12 , further comprising a recirculation line for selectively recirculating etchant gas.  
     
     
         21 . The apparatus of  claim 12 , wherein the first and second etchants are gases capable of etching silicon.  
     
     
         22 . The apparatus of  claim 12 , wherein the second etchant is xenon difluoride.  
     
     
         23 . The apparatus of  claim 22 , wherein the first etchant is a fluorocarbon.  
     
     
         24 . The apparatus of  claim 22 , wherein the first chamber is constructed so as to form a plasma of the first etchant.  
     
     
         25 . The apparatus of  claim 24 , wherein a silicon sample to be etched is disposed within the first chamber and the first etchant is capable of being energized within the first chamber to etch the silicon sample  
     
     
         26 . The apparatus of  claim 12 , wherein the first chamber is constructed so as to form charged species or radicals from the first etchant.  
     
     
         27 . The apparatus of  claim 12 , wherein the first etchant has the formula CxFy.  
     
     
         28 . The apparatus of  claim 27 , wherein the first etchant is selected from C5F12, C3F6, C2F6, C3F8, C4F8, CF4, C2F4, CF2, C2F6, C4F10, C6F14.  
     
     
         29 . The apparatus of  claim 28 , wherein the second etchant is selected from bromine trifluoride, bromine trichloride and xenon difluoride.  
     
     
         30 . The apparatus of  claim 12 , wherein the first chamber is a plasma etching system and the second chamber is a xenon difluoride etching system.  
     
     
         31 . The apparatus of  claim 12 , wherein the first chamber comprises top and bottom electrodes.  
     
     
         32 . The apparatus of  claim 31 , wherein the top and bottom electrodes are separated by a grounded diffuser plate.  
     
     
         33 . The apparatus of  claim 12 , wherein the first etching chamber is a plasma etching chamber that can be operated in remote plasma mode.  
     
     
         34 . The apparatus of  claim 12 , wherein the first chamber is constructed to perform sputter etching or accelerated ion-assisted etching.  
     
     
         35 . The apparatus of  claim 12 , wherein the first chamber is constructed for performing a first etch of a sample and the second chamber is constructed for performing a second etch of the sample.  
     
     
         36 . The apparatus of  claim 35 , wherein the apparatus allows for performing first and second etches on a substrate in the first and second chambers respectively without exposing the substrate to ambient.  
     
     
         37 . The apparatus of  claim 12 , further comprising a source of SF6.  
     
     
         38 . The apparatus of  claim 22 , further comprising a source of an alkyl chlorosilane.  
     
     
         39 . The apparatus of  claim 12 , wherein the first chamber comprises a means to energize the first etchant.  
     
     
         40 . The apparatus of  claim 21 , wherein the first chamber comprises a pair of parallel plate electrodes disposed in the first chamber.  
     
     
         41 . The apparatus of  claim 40 , further comprising a source of electric power to supply power to the electrodes so that gas discharging takes place to generate gas plasma.  
     
     
         42 . The apparatus of  claim 12 , wherein the first etchant has the formula CxFyHz.  
     
     
         43 . The apparatus of  claim 42 , wherein the first etchant is selected from C3HF6, C3H2F6, C3H3F5, CH2F2, C3HF7.