Aug. 16, 2007  2  US 2007/0191243 Al  tor dialectric resin by DOW Chemical Company) organic  ILD with barrier SiC, silicon carbon nitride (SiCN), and  capped with SiO$_{2}$ ,  showing a minimum pattern size of 130  nm.  [0010]  FIG.  3a  is a sidewall area of the etched structure (5  µm) described in FIG.  2  while FIG. 3b is a spectra from an  SEM/EDX analyses of the region shown in FIG.  3a.  [0011]  FIG.  4a  is a SEM photo of patterned wafer speci› mens with an immersion wafer exposure time of 45 seconds  at pH 5.1.  [0012]  FIG.  4b  is a SEM photo of patterned wafer speci› mens with an immersion wafer exposure time of 180 sec› onds (3 min.) at pH 5.1.  [0013]  FIG. 4c is a SEM photo of patterned wafer speci› mens with an immersion wafer exposure time of 45 seconds  at pH 5.5.  [0014]  FIG.  4d  is a SEM photo of patterned wafer speci› mens with an immersion wafer exposure time of 180 sec› onds (3 min.) at pH 5.5.  [0015]  FIG.  4e  is a SEM photo of patterned wafer speci› mens with an immersion wafer exposure time of 45 seconds  at pH 6.0.  [0016]  FIG. 4fis a SEM photo of patterned wafer speci› mens with an immersion wafer exposure time of 180 sec› onds (3 min.) at pH 6.0.  [0017]  FIG.  Sa  is a TEM photo of cross section analyses  on patterned wafer exposure to the invention with approxi› mately pH=5 at an immersion wafer exposure time of 45  seconds.  [0018]  FIG.  Sb  is a TEM photos of cross section analyses  on patterned wafer exposure to the invention with approxi› mately pH=5 at an immersion wafer exposure time of 180  seconds (3 min.).  [0019]  FIG.  6  is a graph showing surface tension changes  upon mixing with  DI  water (rinsing) for the invention with  different surfactants versus reference (no surfactant).  [0020]  FIG.  7a  is a SEM photo of patterned SiLKfi  organic ILD wafers of the kind described with reference to  FIG.  2  prior to cleaning (no exposure, reference).  [0021]  FIG.  7b  is a SEM photo of patterned SiLKfi  organic ILD wafers of the kind described with reference to  FIG.  2  indicating the results of wafer cleaning with the  invention at an approximate pH=5 for time periods of 15-45  seconds using a single wafer spray tool.  [0022]  FIG.  8  is a graph of electronic test results repre› sented as serpentine line resistance on patterned SiLKfi  organic ILD wafers of the kind described with reference to  the structure in FIG.  2  and the resistance curves represent  wafers processed according to the invention at the condi› tions described in FIGS.  7a  and  7b  followed by metallization  and resistance testing.  [0023]  According to the invention, an aqueous system of  ionized fluorine, citric acid-amine buffer, and a unique  surface active agent mixture, penetrates amorphous post- DETAILED DESCRIPTION OF THE  INVENTION  etch polymer residues and complexes silica and copper  while dispersing particulates which subsequently proceeds  in a single wafer tool process until the area is completely  clean and free of residue. The process is carried-out without  the serious attack to adjacent metals and materials needed in  the device stack, a key requirement in material selectivity.  The chemistry applies to both inorganic silica-containing  ILDs (i.e., conventional oxide, SiO$_{2}$ )  and to organic mate› rials which offer ultra-low dielectric constants.  [0024]  The novel system of the invention comprises a  formulated product containing essentially (1) approximately  3-20 parts by weight of a weak organic acid exhibiting a pKa  value, i.e., logarithm of acid dissociation constant, between  3-5 such as citric acid and (2) 1 -5 parts by weight of an  inorganic amine conjugate salt of fluorine such as ammo› nium fluoride (AMF). Preferably, the formulated product  also contains (3) sufficient amounts varying from 2-5 parts,  depending upon the desired pH, of an organic amine as a  buffering aid; and ( 4) a mixture of surfactants that include a  nonionic fluorinated-based surfactant and a nonionic hydro› carbon-based surfactant, each in concentrations between  0.01-1 parts, all mixed with  DI  water added in amounts to  meet the weight balance of the formulation. The amine is  added to achieve the desired buffer pH, of between pH=5-6,  and such that the system will produce ionizable fluorine to  a level sufficient to complex with the silica present in the  etch residue and thereby to effect break-up and removal  without compromise to other silica containing materials  present in the stack.  [0025]  As with any semiconductor cleaning process,  knowledge of the materials of construction will help design  a successful chemistry that exhibits the needed performance  and selectivity. Porous-type ILDs have lower-K values as  compared to dense ILDs. Material porosity, which drives  down the K-value, also absorbs residue and moisture during  the cleaning process. Residue and moisture absorbed into  the dielectric compromise its K-value. Further, many porous  materials become brittle after processing and will lead to  cracking, which is detrimental during chemical mechanical  planarization (CMP) and packaging. Therefore, the efforts to  implement small pore size, high hardness and modulus, and  low coefficient of thermal expansion (CTE) of porous  chemical vapor deposition (CVD) and spin-on inorganic  ILDs, may be lost during integration after exposure to  certain cleaning processes and result in poor K-values and  mechanical degradation.  [0026]  During integration,  plasma etching processes  involve resist that is broken down in the plasma and dis› tributed over the wafer, most commonly along the vertical  areas of the etch locations. This "redeposition" of resist is  needed to ensure anisotropic etching, whereby the post-etch  residue helps to focus the etch process vertically instead of  horizontally. Anisotropic etching continues until a dissimilar  material or metal ( etch stop) is detected at the bottom of the  topography, commonly used as an indicator for termination.  When etching is completed, it is necessary that the wafer’s  etched devices are cleansed free of any post-etch residue to  provide a clean substrate for subsequent processing.  [0027]  Observing the ILD material will determine the  expected etch residue composition, namely, thermal oxide› based ILDs produce silica and organic ILDs produce carbon.  To confirm the residue composition, characterization may be 