Etching methods, RIE methods, and methods of increasing the stability of photoresist during RIE

Abstract

An etching method includes applying a photoresist over a substrate, forming an opening in the photoresist, and etching the substrate under the opening using a plasma generated with a gas composition containing argon and an amount of higher atomic mass inert gas. The amount may be effective to increase photoresist stability compared to otherwise identical etching lacking any of the higher atomic mass inert gas. The photoresist may have a composition sensitized to an actinic energy wavelength of 248 nm or less. A method of increasing the stability of 248 nm or less photoresist during RIE includes providing a means for reducing electron temperature of a plasma and etching a substrate exposed through photoresist openings without substantially destabilizing the photoresist.

I claim:  
     
         1 . An etching method comprising: 
 applying a photoresist over a substrate, the photoresist having a composition sensitized to an actinic energy wavelength of 248 nm or less;    forming an opening in the photoresist; and    etching the substrate under the opening using a plasma generated with a gas composition comprising argon and an amount of higher atomic mass inert gas, the amount being effective to increase photoresist stability compared to otherwise identical etching lacking any of the higher atomic mass inert gas.    
     
     
         2 . The method of  claim 1  wherein the photoresist is sensitized to an actinic energy wavelength of 248 nm.  
     
     
         3 . The method of  claim 1  wherein the substrate comprises a bulk semiconductive wafer.  
     
     
         4 . The method of  claim 1  wherein the forming an opening comprises: 
 exposing a selected portion of the photoresist to actinic energy having a wavelength of 248 nm or less;  
 developing the photoresist; and  
 forming the opening through the photoresist.  
 
     
     
         5 . The method of  claim 1  wherein the etching comprises reactive ion etching.  
     
     
         6 . The method of  claim 1  wherein generating the plasma comprises applying a total power density of at least 5 W/cm 2  to a bottom electrode, the bottom electrode receiving the substrate.  
     
     
         7 . The method of  claim 1  wherein generating the plasma comprises applying dual RF frequency, including a RF frequency of greater than 2 MHz to a bottom electrode, the bottom electrode receiving the substrate.  
     
     
         8 . The method of  claim 1  wherein the higher atomic mass inert gas comprises at least one of xenon, krypton, and radon.  
     
     
         9 . The method of  claim 1  wherein inert gases of the gas composition consist of argon and xenon.  
     
     
         10 . The method of  claim 1  wherein the amount comprises from about 30 to 99 vol % of inert gases.  
     
     
         11 . The method of  claim 1  wherein the gas composition is effective to decrease substrate roughness compared to otherwise identical etching lacking any of the higher atomic mass inert gas.  
     
     
         12 . The method of  claim 1  wherein the substrate comprises an electrical contact and the gas composition is effective to decrease contact striation compared to otherwise identical etching lacking any of the higher atomic mass inert gas.  
     
     
         13 . An etching method comprising: 
 applying a photoresist over a substrate, the photoresist having a composition sensitized to an actinic energy wavelength of 248 nm or less;    forming an opening in the photoresist; and    etching the substrate under the opening using a plasma generated with a gas composition comprising an amount of at least one of xenon and krypton, the amount being effective to increase photoresist stability compared to otherwise identical etching using argon or lower atomic mass noble gas in place of the at least one of xenon and krypton.    
     
     
         14 . The method of  claim 13  wherein the forming an opening comprises: 
 exposing a selected portion of the photoresist to actinic energy having a wavelength of 248 nm or less;  
 developing the photoresist; and  
 forming the opening through the photoresist.  
 
     
     
         15 . The method of  claim 13  wherein generating the plasma comprises applying a total power density of at least 5 W/cm 2  to a bottom electrode, the bottom electrode receiving the substrate.  
     
     
         16 . The method of  claim 13  wherein generating the plasma comprises applying dual RF frequency, including a RF frequency of greater than 2 MHz to a bottom electrode, the bottom electrode receiving the substrate.  
     
     
         17 . The method of  claim 13  wherein the gas composition further comprises argon.  
     
     
         18 . The method of  claim 13  wherein the gas composition comprises xenon.  
     
     
         19 . The method of  claim 13  wherein the gas composition comprises krypton.  
     
     
         20 . The method of  claim 13  wherein the gas composition comprises xenon and krypton.  
     
     
         21 . The method of  claim 13  wherein the amount comprises from about 30 to about 100 vol % of an inert gas portion of the gas composition.  
     
     
         22 . The method of  claim 13  wherein the gas composition is effective to decrease substrate roughness compared to otherwise identical etching lacking xenon and krypton.  
     
     
         23 . The method of  claim 13  wherein the substrate comprises an electrical contact and the gas composition is effective to decrease contact striation compared to otherwise identical etching lacking xenon and krypton.  
     
     
         24 . A reactive ion etching method comprising: 
 applying a photoresist over a substrate, the photoresist having a composition sensitized to an actinic energy wavelength of 248 nm or less;    exposing a selected portion of the photoresist to actinic energy having a wavelength of 248 nm or less;    developing the photoresist and forming a plurality of openings through the photoresist; and    etching the substrate under the plurality of openings using a plasma generated from a gas composition comprising argon and an amount of at least one of xenon and krypton, the amount being effective to increase photoresist stability compared to otherwise identical etching lacking xenon and krypton.    
     
     
         25 . The method of  claim 24  wherein generating the plasma comprises applying a total power density of at least 5 W/cm 2  to a bottom electrode, the bottom electrode receiving the substrate.  
     
     
         26 . The method of  claim 24  wherein generating the plasma comprises applying dual RF frequency, including a RF frequency of greater than 2 MHz to a bottom electrode, the bottom electrode receiving the substrate.  
     
     
         27 . The method of  claim 24  wherein inert gases of the gas composition consist of argon and xenon.  
     
     
         28 . The method of  claim 24  wherein inert gases of the gas composition consist of argon and krypton.  
     
     
         29 . The method of  claim 24  wherein inert gases of the gas composition consist of argon, xenon, and krypton.  
     
     
         30 . The method of  claim 24  wherein the amount comprises from about 30 to 99 vol %.  
     
     
         31 . The method of  claim 24  wherein the gas composition is effective to decrease substrate roughness compared to otherwise identical etching lacking xenon and krypton.  
     
     
         32 . The method of  claim 24  wherein the substrate comprises a plurality of electrical contacts and the gas composition is effective to decrease contact striation compared to otherwise identical etching lacking xenon and krypton.  
     
     
         33 . A method of increasing the stability of 248 nm or less photoresist during RIE comprising: 
 forming developed 248 nm or less photoresist on a substrate, the photoresist having openings therethrough;    providing a first inert gas composition in a RIE chamber, the first composition consisting of components having an atomic mass less than or equal to argon;    providing a reactive gas in the RIE chamber;    forming a plasma in the RIE chamber using at least the first composition and applying power density of at least 5 W/cm 2 ;    providing a means for reducing electron temperature of the plasma; and    etching the substrate exposed through the openings using the plasma and the reactive gas without substantially destabilizing the photoresist.    
     
     
         34 . The method of  claim 33  wherein the means for reducing electron temperature comprises providing a second inert gas composition in the RIE chamber and forming the plasma using at least the first and second compositions, the second composition comprising components having an atomic mass greater than argon.  
     
     
         35 . The method of  claim 34  wherein the first composition consists of argon and the second composition consists of at least one of krypton and xenon.  
     
     
         36 . The method of  claim 34  wherein the first and second compositions are mixed before entering the RIE chamber.  
     
     
         37 . The method of  claim 34  wherein a total of any inert gases comprises from about 30 to 99 vol % second composition.  
     
     
         38 . The method of  claim 34  wherein the substrate comprises an electrical contact and the second composition is effective to decrease contact roughening and striation compared to otherwise identical etching lacking the second composition.  
     
     
         39 . The method of  claim 33  wherein the means for reducing electron temperature comprises providing a second gas composition in the RIE chamber and forming the plasma using at least the first and second compositions, the second composition comprising components having an ionization cross-section greater than argon.  
     
     
         40 . The method of  claim 33  wherein the means for reducing electron temperature comprises providing a second gas composition in the RIE chamber and forming the plasma using at least the first and second compositions, the second composition comprising components having an ionization voltage less than argon.  
     
     
         41 . The method of  claim 33  wherein the reactive gas comprises at least one gas selected from the group consisting of halogenated hydrocarbons and halocarbons.  
     
     
         42 . The method of  claim 33  wherein the substrate comprises a bulk semiconductive wafer.  
     
     
         43 . The method of  claim 33  wherein forming the plasma comprises applying dual RF frequency, including a RF frequency of greater than 2 MHz to a bottom electrode, the bottom electrode receiving the substrate.