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 

