Pattern-etching process

Figure 1. Example of a process flow sheet of a pattern-etch process for a wiring-board operation.

The goal of any pattern-etching process is to transfer an exact replica of the mask features to the underlying film. However, this transfer establishes only... 

Etching. After a resist is patterned on a wafer, the exposed or unwanted substrate is removed by etching processes. Subsequentiy the resist is removed, leaving a desired pattern in a functional layer of the integrated circuit. Etching is performed to pattern a number of materials in the IC fabrication process, including blanket polysiHcon, metal layers, and oxide and nitride layers. The etch process for each material is different, and adapted to the material requirements of the substrate. 

During this process, material is selectively removed from the wafer surface as defined by the patterned photoresist in order to define the structure of the previously deposited layer. The etching process is accomplished by exposing the wafer to a plasma, which both chemically reacts with the material to be removed and ph3rslcally ablates it. At the completion of etching, the remaining photoresist is cleared from the wafer. 

The etching resistance of a resist is simply a function of how well the material withstands the pattern transfer processes used in device manufacturing. Its resistance must be sufficiently high to allow precise transfer of the resist image into the underlying substrate with < 10% linewidth change. This is not an easy... 

Schematic of the Si-nMEA fabrication process (a) sputter Au layer on double-side polished wafer (b) pattern Au layer with liftoff process (c) spincoat and cure a polyimide layer (d) perform the double-sided photolithography to pattern etch pits (e) etch Si in ICP-DRIE to form Au/Si electrode (f) dice the wafer into a single die (g) RIE etch the polyimide layer with a shadow mask to expose current collecting region (h) electroplate Pt black on Au layer (i) sandwich both electrodes with Nafion 112 in a hot-press bonder. (Reprinted from J. Yeom et al. Sensors Actuators B107 (2005) 882-891. With permission from Elsevier.)...

Once the resist has been patterned, the selected regions of material not protected by photoresist are removed by specially designed etchants, creating the resonator pattern in the wafer. Several isotropic (etching occurs in all directions at the same etch rate) and anisotropic (directional) etching processes are available. Wet chemical etching is an isotropic process that... 

It is always interesting to know the fate of the Fe species remaining on the surface. For the W plug application, after W CMP, the subsequent relevant processes are the deposition, patterning and etch of the Ti-Al (aluminum)-TiN stack. The Fe residuals on the surface will not cause any problem for the metal deposition because the entire surface is covered by metals. However, a problem may occur in the metal etch process because the BCI3 plasma chemistry can not etch away Fe. The reaction products between Fe and BCI3 are FeCl complexes, which are nonvolatile [22]. They... 

Etchant Resistance. Etchant resistance refers to the ability of the resist to withstand the etching environment during the pattern transfer process. The most common method of pattern transfer is wet chemical etching which places emphasis on the adhesion and chemical stability of the resist. Etchant solutions may be either acidic or basic, depending on the type of substrate to be etched. For example, buffered hydrofluoric acid is used to etch Si02. However, lateral penetration of the chemical etchant is significant for thick substrate films and... 

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