Plasma etching parameters

C. Parameter Control At present, the most serious impediment to routine use of plasma etching is the large number of parameters that affect the process. As noted, both gas phase considerations and plasma-surface interactions must be controlled. The problem is illustrated in Figure 7 32). Naturally, if the basic plasma parameters (A, /(e), r) could be con-... 

It has been found, however, that the etch rate of PBS can be reasonably controlled in both oxygen and CF4/O2 plasmas if the substrate temperature is kept below room temperature (9). This fact has been utilized to reduce the defect density in the manufacture of chrome photomasks by exposing the developed PBS pattern to a low-temperature oxygen plasma (descum) prior to wet-etching the chrome. We have now found that the plasma-etch resistance of PBS in a CF4/O2 plasma can be markedly enhanced at room temperature simply by exposing the resist to a short oxygen plasma pretreatment prior to exposure to the fluorinated plasma. This effect can be used in a variety of pattern transfer processes to controllably generate submicron features on wafers and masks. This paper examines the parameters associated with this effect, proposes a mechanism to account for the results and delineates some possible pattern transfer processes. 

Further studies have shown, however, that under appropriately chosen plasma etching conditions, poly(alkenylsilane sulfone)s can be passivated in an oxygen plasma like other organosilicon polymers (72,73), but the passivation process depends strongly on the plasma processing parameters. In this paper, we report the results of our studies on the degradation and passivation processes of a typical poly(alkenylsilane sulfone), viz., poly(3-butenyltrimethylsilane sulfone) (PBTMSS) (13) in oxygen plasmas. 

Unlike W plasma etch back process, the typical W CMP process usually removes the adhesion layer such as Ti/TiN or TiN during the primary polish. As a result, during the over polish step there is some oxide loss. Since the oxide deposition, planarization CMP (oxide CMP), and tungsten CMP steps are subsequent to each other, the oxide thickness profile could become worse further into the process flow. Therefore, the across-wafer non-uniformity of the oxide loss during W CMP process is one of the very important process parameters needs to be optimized. To determine the effect of the process and hardware parameters on the polish rate and the across-wafer uniformity, designed experiments were run and trends were determined using analysis of variance techniques. Table speed, wafer carrier speed, down force, back pressure, blocked hole pattern, and carrier types were examined for their effects on polish rate and across-wafer uniformity. The variable ranges encompassed by the experiments used in this study are summarized in Table I. 

The plasma parameters of f=5 cm mln (at STP), p=0.015 torr and w 100 watts are the same In all cases. The ESCA data Immediately affirm that both molybdenum and copper are Incorporated Into the polymer films although as previously noted the method of cathode erosion must be different In the two cases, (chemical plasma etching versus physical sputtering). Consideration of the relative signal Intensities, corrected for the total relative sensitivities of the core levels, derived from standard homogeneous samples, allows estimates of the empirical formulae to be written for these materials as follows [C3F4 oOo.6 °0.3ln... 

In the development of plasma etching processes, it is important to adjust the process parameters to meet requirements such as high etch rates for silicon, good selectivity over both mask and underlying layer, precise control of the line width, good uniformity, underetching as small as possible, and good control of the wall profiles. 

Apart from the tunable parameters, such as RF power, gas composition and flow, and substrate temperature, several other factors affect the plasma etch rates, including impurities in or on the material to be etched, film stress, loading, elapsed time from the start of the etch, materials present in the plasma chamber, and wear of the electrode. 

Kg. 4. Representation of the parameter space in plasma etching. The key internal plasma properties (middle) are the bridge between externally controlled variables (top) and the figures of merit (bottom). 

The performance metrics used to judge the quality of a given antireflection coating include optical parameters (n and k), plasma etch rate, coating properties (whether highly planarizing or somewhat conformal), reflectivity, thickness, and compatibility with the given resist to which it is paired. 

These membranes were plasma-etched for different periods before being subjected to TM-AFM study. Figure 5.28 shows the change in the roughness parameter with etching time. In the PPO-CS2 membrane, the roughness parameter increases up to 800 s and then levels off, while in the PPO-TCE membrane, the roughness parameter increases sharply after a lag time of about 800 s. 

The electrochemically deposited single crystalline ZnO nanowires can be applied in LEDs [147, 148]. ZnO nanowire films can be embedded in an insulating spin-coated polystyrene layer. The spin-coating parameters are carefully fine-tuned to completely fill out the space between the ZnO nanowires and produce only a very thin coverage of the nanowire tips. The polystyrene layer thickness at the tips can be further reduced by the plasma etching treatment to make the n-type ZnO tip junctions outside. A top... 

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