Low k film application for interlevel dielectric and method of cleaning etched features

Abstract

Methods of selectively removing post-etch polymer material and dielectric antireflective coatings (DARC) without substantially etching an underlying carbon-doped low k dielectric layer, and compositions for the selective removal of a DARC layer and post-etch polymer material are provided. A composition comprising trimethylammonium fluoride is used to selectively etch a dielectric antireflective coating layer overlying a low k dielectric layer at an etch rate of the antireflective coating layer to the low k dielectric layer that is greater than the etch rate of the antireflective coating to a TEOS layer. The method and composition are useful, for example, in the formation of high aspect ratio openings in low k (carbon doped) silicon oxide dielectric layers and maintaining the integrity of the dimensions of the formed openings during a cleaning step to remove a post-etch polymer and antireflective coating.

What is claimed is:  
     
         1 . A method of forming a conductive structure, comprising the steps of: 
 providing a wafer comprising a substrate and an overlying low k dielectric layer;    forming a layer of dielectric antireflective coating over the low k dielectric layer;    forming a photoresist layer over the dielectric antireflective coating layer;    etching an opening through the low k dielectric layer to an active area on the substrate; and    contacting the wafer with a cleaning solution comprising trimethylammonium fluoride to selectively remove the dielectric antireflective coating layer and post-etch polymer material.    
     
     
         2 . The method of  claim 1 , wherein the cleaning solution comprises an amount of trimethylammonium fluoride to provide an etch rate ratio of the dielectric antireflective coating layer to the low k dielectric layer greater than the etch rate ratio of the dielectric antireflective coating layer to a TEOS layer.  
     
     
         3 . The method of  claim 2 , wherein the etch rate is greater than 2:1.  
     
     
         4 . The method of  claim 2 , wherein the etch rate is greater than 5:1.  
     
     
         5 . The method of  claim 2 , wherein the etch rate is greater than 10:1.  
     
     
         6 . The method of  claim 2 , wherein the cleaning solution comprises about 10 to about 40 wt % of trimethylammonium fluoride.  
     
     
         7 . The method of  claim 2 , wherein the cleaning solution further comprises hydrogen fluoride.  
     
     
         8 . The method of  claim 7 , wherein the cleaning solution comprises about 10 to about 40 wt % of trimethylammonium fluoride and up to about 10 wt % hydrogen fluoride.  
     
     
         9 . The method of  claim 2 , wherein the cleaning solution further comprises trimethylammonium hydroxide.  
     
     
         10 . The method of  claim 9 , wherein the cleaning solution comprises about 10 to about 40 wt % of trimethylammonium fluoride and about 0 to about 25-wt % trimethylammonium hydroxide.  
     
     
         11 . The method of  claim 1 , wherein the cleaning solution has a pH of about 3.5 to about 14.  
     
     
         12 . The method of  claim 1 , wherein the temperature of the cleaning solution is about 5° C. to about 65° C.  
     
     
         13 . The method of  claim 1 , wherein the temperature of the cleaning solution is about 20° C. to about 50° C.  
     
     
         14 . The method of  claim 1 , wherein the contacting step is for a time period effective to remove the dielectric antireflective coating layer and the post-etch polymer with substantially no etching of the low k dielectric layer.  
     
     
         15 . The method of  claim 14 , wherein the contacting step comprises removing up to about 600 angstroms of the dielectric antireflective coating layer within an about six minute time period.  
     
     
         16 . The method of  claim 14 , wherein the contacting step comprises an about 1 to about 15 minute time period.  
     
     
         17 . The method of  claim 14 , wherein the contacting step results in etching of less than 50 angstroms of the low k dielectric layer.  
     
     
         18 . The method of  claim 1 , wherein the contacting step comprises dipping the wafer in the cleaning solution.  
     
     
         19 . The method of  claim 1 , wherein the contacting step comprises spraying the cleaning solution onto the wafer.  
     
     
         20 . The method of  claim 1 , further comprising after the contacting step, the step of depositing a conductive material to fill the opening.  
     
     
         21 . A method of forming a conductive structure, comprising the steps of: 
 providing a wafer comprising a substrate, an overlying carbon doped low k dielectric layer, an overlying dielectric antireflective coating layer, and an opening formed through said layers to the substrate; and    contacting the wafer with a cleaning solution comprising an amount of trimethylammonium fluoride to selectively etch the dielectric antireflective coating layer and overlying polymer material.    
     
     
         22 . The method of  claim 21 , wherein the cleaning solution provides an etch rate ratio of the dielectric antireflective coating layer to the low k dielectric layer greater than the etch rate ratio of the dielectric antireflective coating layer to a TEOS layer.  
     
     
         23 . The method of  claim 22 , wherein the rate of etching the dielectric antireflective coating layer to the rate of etching the low k dielectric layer is a ratio greater than about 5:1.  
     
     
         24 . The method of  claim 22 , wherein the rate of etching the dielectric antireflective coating layer to the rate of etching the low k dielectric layer is a ratio greater than about 10:1.  
     
     
         25 . The method of  claim 21 , wherein the contacting step is for a time period of about 1 to about 15 minutes, and less than 50 angstroms of the dielectric layer is etched.  
     
     
         26 . A method off forming a conductive structure, comprising the steps of: 
 forming a carbon doped low k dielectric layer over a substrate of a wafer;    forming a dielectric antireflective coating layer over the low k dielectric layer;    forming a photoresist layer comprising an organic polymer material over the dielectric antireflective coating layer;    etching an opening through the dielectric layer to the substrate; and    contacting the wafer with a cleaning solution comprising an effective amount of trimethylammonium fluoride to selectively remove the dielectric antireflective coating layer and post-etch polymer.    
     
     
         27 . The method of  claim 26 , wherein the cleaning solution provides an etch rate ratio of the dielectric antireflective coating layer to the low k dielectric layer of greater than 5:1.  
     
     
         28 . The method of  claim 26 , wherein the cleaning solution provides an etch rate ratio of the dielectric antireflective coating layer to the low k dielectric layer of greater than 10:1.  
     
     
         29 . The method of  claim 26 , wherein the cleaning solution comprises about 10 to about 40 wt % of trimethylammonium fluoride.  
     
     
         30 . The method of  claim 29 , wherein the cleaning solution further comprises up to about 10 wt % hydrogen fluoride.  
     
     
         31 . The method of  claim 29 , wherein the cleaning solution further comprises up to about 25 wt % trimethylammonium hydroxide.  
     
     
         32 . The method of  claim 26 , wherein the step of forming the carbon-doped low k dielectric layer comprises depositing a carbon-substituted silane source gas and an oxygen source gas onto the substrate.  
     
     
         33 . The method of  claim 32 , wherein the silane source gas comprises trimethylsilane, and the oxygen source is selected from the group consisting of N 2 O and O 2 .  
     
     
         34 . The method of  claim 32 , wherein the step of forming the low k dielectric layer comprises flowing about 60 to about 1000 sccm of the silane source gas, and about 50 to about 500 sccm of the oxygen source gas over the substrate.  
     
     
         35 . The method of  claim 34 , wherein the step of forming the low k dielectric layer further comprises flowing about 200 to about 1000 sccm of helium.  
     
     
         36 . The method of  claim 26 , wherein the step of forming the low k dielectric layer comprises flowing about 60 to about 1000 sccm trimethylsilane and about 200 to about 1000 sccm N 2 O.  
     
     
         37 . The method of  claim 36 , wherein the step of forming the low k dielectric layer further comprises flowing about 200 to about 1000 sccm of helium.  
     
     
         38 . The method of  claim 26 , wherein the step of forming the low k dielectric layer comprises flowing about 500 to about 700 sccm trimethylsilane, and about 80 to about 150 sccm O 2 .  
     
     
         39 . The method of  claim 26 , wherein the step of forming the low k dielectric layer is at a temperature of about 300° C. to about 450° C.  
     
     
         40 . The method of  claim 26 , wherein the step of forming the low k dielectric layer comprises plasma enhanced chemical vapor deposition.  
     
     
         41 . The method of  claim 26 , wherein the low k dielectric layer has a dielectric constant of about 2.5 to about 3.5.  
     
     
         42 . The method of  claim 26 , wherein the step of forming the dielectric antireflective coating layer comprises depositing a plasma comprising a silicon source gas and an oxygen source gas.  
     
     
         43 . The method of  claim 42 , wherein the silicon source gas comprises silane, and the oxygen source gas comprises N 2 O.  
     
     
         44 . The method of  claim 26 , wherein the dielectric antireflective coating layer comprises silicon-rich oxynitride or a silicon-rich oxide.  
     
     
         45 . The method of  claim 44 , wherein the dielectric antireflective coating layer comprises a silicon-rich oxynitride having the formula Si x O y N z :H where x is 0.30 to 0.65, y is 0.02 to 0.56, and z is 0.05 to 0.33.  
     
     
         46 . The method of  claim 44 , wherein the dielectric antireflective coating layer comprises a silicon-rich oxide having the formula Si x O y :H, where x is 0.30 to 0.65, and y is 0.25 to 0.60.  
     
     
         47 . The method of  claim 26 , wherein the step of forming the dielectric antireflective coating layer comprises chemical vapor deposition.  
     
     
         48 . The method of  claim 26 , wherein the step of forming the dielectric antireflective coating layer comprises plasma enhanced chemical vapor deposition.  
     
     
         49 . The method of  claim 42 , wherein the step of forming the dielectric antireflective coating layer comprises flowing about 40 to about 300 sccm of a silicon source gas, and about 80 to about 600 sccm of an oxygen source gas.  
     
     
         50 . The method of  claim 26 , wherein the photoresist layer comprises a novolac resin.  
     
     
         51 . The method of  claim 26 , wherein the step of forming the opening comprises a plasma etch process.  
     
     
         52 . The method of  claim 26 , wherein the step of etching the opening comprises a damascene etch process.  
     
     
         53 . The method of  claim 52 , wherein the opening comprises a contact opening and a trench.  
     
     
         54 . The method of  claim 52 , wherein the opening comprises a contact opening or via.  
     
     
         55 . The method of  claim 26 , wherein the step of etching the opening comprises exposing an active area on the substrate.  
     
     
         56 . The method of  claim 55 , wherein the active area comprises a metal line.  
     
     
         57 . The method of  claim 55 , wherein the active area comprises a source/drain region.  
     
     
         58 . A method of forming a dual damascene structure in a semiconductor device, comprising the steps of: 
 providing a substrate comprising an active area;    forming a low k dielectric layer over the active area;    forming a dielectric antireflective coating layer over the low k dielectric layer;    forming a photoresist layer over the dielectric antireflective coating layer;    etching the insulating layer to form a trench and an opening extending to the active area in the substrate; and    selectively removing post-etch polymer and the dielectric antireflective coating layer with a cleaning solution comprising trimethylammonium fluoride in an amount effective to selectively etch the dielectric antireflective coating layer to the low k dielectric layer at an etch rate ratio of greater than 5:1.    
     
     
         59 . The method of  claim 58 , wherein the etch rate ratio is greater than 10:1.  
     
     
         60 . The method of  claim 58 , wherein the cleaning solution comprises about 10 to about 40 weight % trimethylammonium fluoride.  
     
     
         61 . The method of  claim 60 , wherein the cleaning solution further comprises up to about 10 weight % hydrogen fluoride.  
     
     
         62 . The method of  claim 60 , wherein the cleaning solution further comprises up to about 25 wt % trimethylammonium hydroxide.  
     
     
         63 . A method of cleaning a surface, comprising the steps of: 
 providing a wafer substrate comprising overlying layers of a carbon-doped low k dielectric layer, and a dielectric antireflective coating layer; and    contacting the wafer with a cleaning solution comprising trimethylammonium fluoride to selectively remove the dielectric antireflective coating layer and polymer material on the wafer.    
     
     
         64 . The method of  claim 63 , wherein the cleaning solution comprises the trimethylammonium fluoride in an amount to provide an etch rate ratio of the dielectric antireflective coating layer and the low k dielectric layer of greater than 5:1.  
     
     
         65 . The method of  claim 63 , wherein the cleaning solution comprises the trimethylammonium fluoride in an amount to provide an etch rate ratio of the dielectric antireflective coating layer and the low k dielectric layer of greater than 10:1.  
     
     
         66 . The method of  claim 63 , wherein the cleaning solution comprises about 10 to about 40% wt trimethylammonium fluoride.  
     
     
         67 . The method of  claim 66 , wherein the cleaning solution further comprises up to about 10 wt % hydrogen fluoride.  
     
     
         68 . The method of  claim 66 , wherein the cleaning solution further comprises up to about 25 wt % trimethylammonium fluoride.  
     
     
         69 . The method of  claim 63 , wherein the dielectric antireflective coating layer comprises silicon-rich oxynitride having the formula Si x O y N z :H where x is 0.30 to 0.65, y is 0.02 to 0.56, and z is 0.05 to 0.33.  
     
     
         70 . The method of  claim 63 , wherein the dielectric antireflective coating layer comprises a silicon-rich oxide having the formula Si x O y :H, where x is 0.30 to 0.65, and y is 0.25 to 0.60.  
     
     
         71 . The method of  claim 63 , wherein the wafer further comprises an opening etched into the low k dielectric layer to the substrate, the opening having a critical dimension.  
     
     
         72 . The method of  claim 71 , wherein the opening has a width dimension less than about 0.25 μm, and the step of removing etches less than about 50 angstroms of the low k dielectric layer during a contact period with the cleaning solution of up to about 15 minutes.  
     
     
         73 . The method of  claim 71 , wherein the opening has an aspect ratio greater than about 0.5.  
     
     
         74 . The method of  claim 63 , wherein the contacting step is for a time effective to remove the polymer material and the dielectric antireflective coating layer, wherein less than about 50 angstroms of the low k dielectric layer are removed.  
     
     
         75 . A semiconductor processing method, comprising the steps of: 
 providing a substrate comprising an active area;    chemical vapor depositing a carbon-doped low k dielectric layer over a substrate by flowing about 60 to about 700 sccm of a carbon-substituted silane source gas, and about 100 to about 1000 sccm of an oxygen source gas over the active area on the substrate;    chemical vapor depositing a dielectric antireflective coating layer comprising silicon-rich oxynitride or silicon-rich oxide over the dielectric layer,    forming a layer of photoresist over the dielectric antireflective coating layer;    photolithographically patterning the photoresist layer to form a patterned masking layer;    etching the low k dielectric layer to form an opening therethrough to the active area on the substrate; and    applying a cleaning solution comprising trimethylammonium fluoride for a time effective to selectively remove the dielectric antireflective coating layer and post-etch polymer at an etch rate ratio of the dielectric antireflective coating layer to the low k dielectric layer of greater than 5:1.    
     
     
         76 . The method of  claim 75 , wherein the etch rate ratio of the dielectric antireflective coating layer to the low k dielectric layer of greater than 10:1.  
     
     
         77 . The method of  claim 75 , wherein the low k dielectric layer has a dielectric constant of about 2.5 to about 3.5.  
     
     
         78 . The method of  claim 75 , wherein the cleaning solution comprises about 10 to about 40 wt % trimethylammonium fluoride.  
     
     
         79 . The method of  claim 78 , wherein the cleaning solution further comprises up to about 10 wt % hydrogen fluoride.  
     
     
         80 . The method of  claim 78 , wherein the cleaning solution further comprises about 0 to about 25 wt % trimethylammonium hydroxide.  
     
     
         81 . The method of  claim 75 , wherein the applying step comprises removing up to about 600 angstroms of the dielectric antireflective coating layer and substantially no measurable removal of the low k dielectric layer over an about 6 minute time period.  
     
     
         82 . The method of  claim 75 , wherein less than 50 angstroms of the low k dielectric layer is removed.  
     
     
         83 . The method of  claim 75 , wherein the step of depositing the low k dielectric layer comprises flowing about 60 to about 150 sccm trimethylsilane, and about 300 to about 500 sccm N 2 O.  
     
     
         84 . The method of  claim 75 , wherein the step of depositing the low k dielectric layer comprises flowing about 500 to about 700 sccm trimethylsilane, and about 80 to about 150 sccm O 2 .  
     
     
         85 . A cleaning composition comprising: 
 an aqueous solution comprising one or more cleaning agents in amounts effective to selectively remove a dielectric antireflective coating layer overlying a carbon-doped low k dielectric layer at an etch rate of the dielectric antireflective coating layer to the low k dielectric layer that is greater than the etch rate of the dielectric antireflective coating layer to a TEOS layer.    
     
     
         86 . The cleaning composition of  claim 85 , wherein the etch rate of the dielectric antireflective coating layer to the low k dielectric layer is greater than 5:1.  
     
     
         87 . The cleaning composition of  claim 85 , wherein the etch rate of the dielectric antireflective coating layer to the low k dielectric layer is greater than 10:1.  
     
     
         88 . The cleaning composition of  claim 85 , comprising trimethylammonium fluoride.  
     
     
         89 . The cleaning composition of  claim 88 , comprising about 10 to about 40 wt % trimethylammonium fluoride.  
     
     
         90 . The cleaning composition of  claim 89 , further comprising up to about 10 wt % hydrogen fluoride.  
     
     
         91 . The cleaning composition of  claim 89 , further comprising up to about 25 wt % trimethylammonium hydroxide.  
     
     
         92 . The cleaning composition of  claim 88 , having a pH of about 3.5 to about 14.  
     
     
         93 . A cleaning composition, comprising: an aqueous solution comprising about 10 to about 40 wt % trimethylammonium fluoride to selectively etch an dielectric antireflective coating layer overlying a low k dielectric layer; the dielectric antireflective coating layer comprising a silicon-rich oxynitride or silicon-rich oxide.  
     
     
         94 . The cleaning composition of  claim 93 , further comprising about 0 to about 10 wt % hydrogen fluoride.  
     
     
         95 . The cleaning composition of  claim 94 , comprising the trimethylammonium fluoride and hydrogen fluoride in amounts such that contact of the cleaning composition with a low k dielectric layer for a time period of up to about 15 minutes removes less than 50 angstroms of the low k dielectric layer.  
     
     
         96 . The cleaning composition of  claim 93 , further comprising about 0 to about 25 wt % trimethylammonium hydroxide.  
     
     
         97 . The cleaning composition of  claim 96 , comprising the trimethylammonium fluoride and trimethylammonium hydroxide in amounts such that contact of the cleaning composition with a low k dielectric layer for a time period of up to about 15 minutes removes less than 50 angstroms of the low k dielectric layer.  
     
     
         98 . The cleaning composition of  claim 93 , wherein the low k dielectric layer comprises a carbon-doped low k dielectric material.  
     
     
         99 . The cleaning composition of  claim 98 , wherein the low k dielectric layer comprises silicon oxide formed by chemical vapor deposition of a carbon-substituted silane precursor and an oxygen source gas.  
     
     
         100 . The cleaning composition of  claim 99 , wherein the low k dielectric layer is formed by deposition of trimethylsilane and N 2 O.  
     
     
         101 . The cleaning composition of  claim 99 , wherein the low k dielectric layer is formed by deposition of trimethylsilane and O 2 .  
     
     
         102 . A cleaning composition, comprising: an aqueous solution comprising about 10 to about 40 wt % trimethylammonium fluoride to selectively etch a dielectric antireflective coating layer overlying a low k dielectric layer.  
     
     
         103 . The cleaning composition of  claim 102 , comprising an amount of trimethylammonium fluoride to effect an etch rate ratio of the dielectric antireflective coating layer: the dielectric layer of greater than 5:1.  
     
     
         104 . The cleaning composition of  claim 102 , comprising an amount of trimethylammonium fluoride to effect an etch rate ratio of the dielectric antireflective coating layer: the low k dielectric layer of greater than 10:1.  
     
     
         105 . The cleaning composition of  claim 102 , comprising an amount of trimethylammonium fluoride to effect an etch rate ratio of the dielectric antireflective coating layer: the low k dielectric layer of greater than 100:1.  
     
     
         106 . The cleaning composition of  claim 102 , comprising amounts of the trimethylammonium fluoride such that less than 50 angstroms of the low k dielectric layer is removed after contact of the cleaning composition for up to about 15 minutes.  
     
     
         107 . The cleaning composition of  claim 102 , further comprising 0 to about 10 wt % hydrogen fluoride.  
     
     
         108 . The cleaning composition of  claim 102 , further comprising 0 to about 25 wt % trimethylammonium hydroxide.  
     
     
         109 . The cleaning composition of  claim 102 , wherein the low k dielectric layer comprises a carbon-doped low k dielectric material.  
     
     
         110 . The cleaning composition of  claim 102 , wherein the dielectric antireflective coating layer comprises a silicon-rich oxynitride or silicon-rich oxide.  
     
     
         111 . The cleaning composition of  claim 110 , wherein the dielectric antireflective coating layer comprises a silicon-rich oxynitride of the formula Si x O y N z :H where x is 0.30 to 0.65, y is 0.02 to 0.56, and z is 0.05 to 0.33.  
     
     
         112 . The cleaning composition of  claim 110 , wherein the dielectric antireflective coating layer comprises a silicon-rich oxide of the formula Si x O y :H, where x is 0.30 to 0.65, and y is 0.25 to 0.60.