Reducing twisting in ultra-high aspect ratio dielectric etch

Abstract

An apparatus for etching a dielectric layer contained by a substrate is provided. An etch reactor comprises a top electrode and a bottom electrode. An etch gas source supplies an etch gas into the etch reactor. A first Radio Frequency (RF) source generates a first RF power with a first frequency and supplies the first RF power into the etch reactor, whereas the first frequency is between 100 kilo Hertz (kHz) and 600 kHz. A second RF source generates a second RF power with a second frequency and supplies the second RF power into the etch reactor, whereas the second frequency is at least 10 mega Hertz (MHz).

1 . An apparatus for etching a dielectric layer over a substrate, comprising:
 an etch reactor comprising a top electrode and a bottom electrode;   an etch gas source for supplying an etch gas into the etch reactor;   a first Radio Frequency (RF) source for generating a first RF power with a first frequency and supplying the first RF power into the etch reactor, whereas the first frequency is between 100 kilo Hertz (kHz) and 600 kHz; and   a second RF source for generating a second RF power with a second frequency and supplying the second RF power into the etch reactor, whereas the second frequency is at least 10 mega Hertz (MHz).   
   
   
       2 . The apparatus of  claim 1 , whereas the first frequency is between 200 kHz and 600 kHz. 
   
   
       3 . The apparatus of  claim 1 , whereas the first frequency is between 350 kHz and 450 kHz. 
   
   
       4 . The apparatus of  claim 1 , whereas the first RF power is between 100 Watts (W) to 10000 W. 
   
   
       5 . The apparatus of  claim 1 , whereas the first RF power is between 500 W to 5000 W. 
   
   
       6 . The apparatus of  claim 1 , whereas the first RF source and the second RF source are connected to the bottom electrode. 
   
   
       7 . The apparatus of  claim 1 , further comprising:
 a third RF source for generating a third RF power with a third frequency and supplying the third RF power into the etch reactor, whereas the third frequency is at least 40 MHz.   
   
   
       8 . The apparatus of  claim 7 , whereas the third RF source is connected to the bottom electrode. 
   
   
       9 . The apparatus of  claim 1 , further comprising:
 a controller, whereas the controller is connected to the etch gas source, the first RF source, the second RF source, and the bottom electrode, comprising:
 a processor; and 
 computer readable media, comprising:
 computer readable code for delivering the etch gas into the etch reactor; 
 computer readable code for delivering the first RF power with the first frequency between 100 kHz and 600 kHz into the etch reactor; 
 computer readable code for delivering the second RF power with the second frequency being at least 10 MHz into the etch reactor; and 
 computer readable code for stopping etch gas, the first RF power, and the second RF power from being delivered into the etch reactor after at least one feature with a depth-to-width aspect ratio of at least 15-to-1 is etched into the dielectric layer. 
 
   
   
   
       10 . A method for etching features in a dielectric layer over a substrate, comprising:
 placing the substrate with the dielectric layer on a bottom electrode inside an etch reactor;   delivering an etch gas into the etch reactor;   delivering a first RF power with a first frequency into the etch reactor, whereas the first frequency is between 100 kHz and 600 kHz;   delivering a second RF power with a second frequency into the etch reactor, whereas the second frequency is at least 10 MHz; and   etching the dielectric layer to form at least one ultra-high aspect ratio (UHAR) feature.   
   
   
       11 . The method of  claim 10 , whereas the ultra-high aspect ratio is at least 15-to-1. 
   
   
       12 . The method of  claim 10 , whereas the at least one ultra-high aspect ratio feature has a width no greater than 300 nanometers (nm) and the ultra-high aspect ratio is at least 15-to-1. 
   
   
       13 . The method of  claim 10 , whereas the first frequency is between 200 kHz and 600 kHz. 
   
   
       14 . The method of  claim 10 , whereas the first frequency is between 350 kHz and 450 kHz. 
   
   
       15 . The method of  claim 10 , whereas the first RF power is between 100 W to 10000 W. 
   
   
       16 . The method of  claim 10 , whereas the first RF power is between 500 W to 5000 W. 
   
   
       17 . The method of  claim 10 , whereas the first RF power is delivered into the etch reactor by capacitive coupling. 
   
   
       18 . The method of  claim 10 , further comprising:
 delivering a third RF power with a third frequency into the etch reactor, whereas the third frequency is at least 40 MHz.   
   
   
       19 . The method of  claim 10 , whereas the dielectric layer is of a silicon oxide based material.