Bulk etch rates of CR-39 at high etchant concentrations:diffusionlimited etching

Systematic CR-39 bulk etching experiments were conducted over a wide range of concentrations(2–30 N)of NaOH-based etchant.Critical analysis and a deep discussion of the results are presented.A comprehensive nuclear track chemical etching data bank was developed.Three regimes of CR-39 bulk etching were identified.Regime I spans etchant concentrations from 2 to 12 N.Regime II spans concentrations from 12 to 25 N.We call this the dynamic bulk etching regime.Regime III is for concentrations greater than 25 N.In this regime,the bulk etch rate is saturated with respect to the etchant concentration.This classification is discussed and explained.The role of ethanol in NaOH-based etchants is explored and discussed.A parameter called the “reduced bulk etch rate” is defined here,which helps in analyzing the dependence of bulk etching on the amount of ethanol in the etchant.The bulk etch rate shows a natural logarithmic dependence on the density of ethanol in the etchant.

TDC Model for PSG Sacrificial Layer Etching with Hydrofluoric Acid

HF etching of sacrificial layers with different The existing model cannot fit the experimental data well perimental data increases with etching time. A modified structures, namely channel, bubble, and joint-channel, is studied. The error of etching rate between the existing model and the exmodel considering the diffusion coefficient as a function of HF concentration and temperature is proposed. The etching rate coefficient as a function of temperature and the effect of reaction production are also considered in the modified model. For the joint-channel structure, a new mathematical model for the etching profile is also adopted. Experimental data obtained with channel, bubble, and joint-channel structures are compared with the modified model and the previous model. The results show that the modified model matches the experiments well.

An Improvement on Si-etching Tetramethyl Ammonium Hydroxide Solution

An optimal concentration of the etching solution for deep etching of silicon, including 3% tetramethyl ammonium hydroxide and 0.3% (NH4)2S2O8, was achieved in this paper. For this etching solution, the etching rates of silicon and silicon dioxide were about 1.1μm·min-1 and 0.5nm·min-1, respectively. The etching ratio between (100) and (111) planes was about 34:1, and the etched surface was very smooth.

Research on the Mechanism of Multilayer Reactive Ion Etching

Dry etching has now become one of the key processes of high ratio of depth to width microstructure and fine patterning. This paper presents a new dry etching technology - multilayer reactive ion etching technology （MRIE）. By taking full advantage of the spatial layout of the chamber, arranging multi-layer electrodes and transporting the discharged gas by a layered air supply device, the function of simultaneous etching in every reaction chamber （layer） is realized. This method can significantly enhance the productivity. Taking the photoresist etching by MRIE as an example, the law and mechanism influencing the etching rate and uniformity were analyzed for different conditions. The result shows that when plate distance is 50/55/60 mm （from bottom to top）, and vacuum degree, ratio of O2 to Ar, RF source power, and continuous etching time are respectively 40 Pa, 1/2, 600 W, and 20 min, the optimal process is achieved. The average etching rate and uniformity are 143.93 A/min and 9.8%, respectively.

Study on the Performance of PECVD Silicon Nitride Thin Films

Mechanical properties and corrosion resistance of Si3N4 films are studied by using different experiment parameters, such as plasma enhanced chemical vapor deposition(PECVD) RF power, ratio of reaction gas, reaction pressure and working temperature. The etching process of Si3N4 is studied by inductively coupled plasma (ICP) with a gas mixture of SF6 and O2. The influence of the technique parameters, such as ICP power, DC bias, gas composition, total flow rate, on the etching selectivity of Si3N4/EPG533 which is used as a mask layer and the etching rate of Si3N4 is studied, in order to get a better etching selectivity of Si3N4/EPG533 with a faster etching rate of Si3N4. The optimized process parameters of etching Si3N4 by ICP are obtained after a series of experiments and analysis. Under the conditions of total ICP power of 250 W, DC bias of 50W, total flow rate of 40 sccm and O2 composition of 30%, the etching selectivity of 2.05 can be reached when Si3N4 etching rate is 336 nm/min.

Micro-track structure analysis for 100 MeV Si ions in CR-39 by using atomic force microscopy

To analyze the micro-track structure of heavy ions in a polymer material, parameters including bulk etch rate, track etch rate, etch rate ratio, and track core size were measured. The pieces of CR-39 were exposed to 100 MeV Si ions with normal incidence and were etched in 6.25N NaOH solution at 70 ℃. Bulk etch rate was read out by a profilemeter after several hours of etching. The other parameters were obtained by using an atomic force microscope （AFM） after a short time of etching. We have measured the second etch pits and minute etch pits to obtain the track growth curve and three dimension track structures to track the core size and etch rate measurements. The local dose of the track core was calculated by the δ-ray theory. In our study, we figure out that the bulk etch rate Vb=（1.58±0.022） μm/h, the track etch rate Vt=（2.90±0.529） μ/h, the etch rate ratio V=1.84±0.031, and the track core radii r≈4.65 nm. In the meantime, we find that the micro-track development violates the traditional track-growth model. For this reason, a scenario is carried out to provide an explanation.

Bulk Etch Rate of LR 115 Polymeric Radon Detector

In this study, we used strippable LR 115 type 2 which is a Solid State Nuclear Track Detector (SSNTD) widely known for radon gas detection and measurement. The removed thickness of the active layer of samples of this SSNTD, were determined by measuring the average initial thickness (before etching) and residual thickness after 80 to 135 minutes chemical etching in the standard conditions, using an electronic comparator. These results allowed the calculation of the bulk etch rate of this detector in a simple way. The mean value obtained is (3.21 ± 0.21) μm/h. This value is in close agreement with those reported by different authors. It is an important parameter for alpha track counting on the sensitive surface of this polymeric detector after chemical etching because track density depends extremely on its removed layer. This SSNTD was then used for environmental radon gas monitoring in Côte d’Ivoire.

Effect of Width Ratio on the Etching Behavior of Joint Channel Structure

Effect of width ratio on the etching behaviour of joint channel structure is studied. By theory and experiments, the etching behaviors of joint channel with different width ratios are compared. The results show that the effect of width ratio on the etching behavior is much different for the narrow-wide joint channel and the wide-narrow structure. For the narrow-wide joint channel,the etching process depends not only on the width ratio but also on the width of the channel. The etching rate and concentration of etching front at each stage are very close with the same width ratio. The etching time required at each stage increases with the channel width, but the final total etching time is very close if the length of the wide channel is much longer. For the wide-narrow joint channel, the etching process depends only on the width ratio. For wide-narrow joint channel, the etching process, including the required etching time, is absolutely the same with the same width ratio. The etching rate and concentration of etching front at each stage increases with the rise of the width ratio, while the total etching time decreases with the increase of width ratio.

Microtrenching effect of SiC ICP etching in SF_6/O_2 plasma

Inductively coupled plasma （ICP） etching of single crystal 6H-silicon carbide （SIC） is investigated using oxygen （O2）-added sulfur hexafluoride （SF6） plasmas. The relations between the microtrenching effect and ICP coil power, the composition of the etch gases and different bias voltages are discussed. Experimental results show that the microtrench is caused by the formation of a SiFxOy layer, which has a greater tendency to charge than SiC, after the addition of O2. The microtrenching effect tends to increase as the ICP coil power and bias voltage increase. In addition, the angular distribution of the incident ions and radicals also affects the shape of the microtrench.

Dry etching of new phase-change material Al_(1.3)Sb_3Te in CF_4/Ar plasma

The dry etching characteristic of AlSbTe film was investigated by using a CF/Ar gas mixture.The experimental control parameters were gas flow rate into the chamber,CF/Ar ratio,the Oaddition,the chamber background pressure,and the incident RF power applied to the lower electrode.The total flow rate was 50 sccm and the behavior of etch rate of AlSbTe thin films was investigated as a function of the CF/Ar ratio,the Oaddition,the chamber background pressure,and the incident RF power.Then the parameters were optimized.The fast etch rate was up to 70.8 nm/min and a smooth surface was achieved using optimized etching parameters of CFconcentration of 4%,power of 300 W and pressure of 80 mTorr.

Synergic effect of chelating agent and oxidant on chemical mechanical planarization

Chemically dominant alkaline slurry, which is free of BTA （benzotriazole） and other inhibitors, was investigated. The synergic effect of the chelating agent and oxidant on the chemical mechanical planarization （CMP） was taken into consideration. Copper CMP slurry is mainly composed of an oxidizer, nonionic surfactant, chelating agent and abrasive particles. The effect of different synergic ratios of oxidant with chelating agent on the polishing removal rate, static etch rate and planarization were detected. The planarization results reveal that with the increase of oxidant concentration, the dishing value firstly diminished and then increased again. When the synergic ratios is 3, the dishing increases the least. A theoretical model combined with chemical-mechanical kinetics process was proposed in the investigation, which can explain this phenomenon. Based on the theoretical model, the effect of synergic ratios of oxidant with chelating agent on velocity D-value （convex removal rate minus recessed removal rate） was analyzed. The results illustrate that when the synergic ratio is between 2.5-3.5, the velocity D-value is relatively higher, thereby good planarization can be achieved in this interval. This investigation provides a new guide to analyze and study copper line corrosion in the recessed region during copper clearing polishing.

Benzotriazole removal on post-Cu CMP cleaning

This work investigates systematically the effect of FA/O II chelating agent and FA/O I surfactant in alkaline cleaning solutions on benzotriazole （BTA） removal during post-Cu CMP cleaning in GLSI under the con- dition of static etching. The best detergent formulation for BTA removal can be determined by optimization of the experiments of single factor and compound cleaning solution, which has been further confirmed experimentally by contact angle （CA） measurements. The resulting solution with the best formulation has been measured for the actual production line, and the results demonstrate that the obtained cleaning solution can effectively and efficiently remove BTA, CuO and abrasive SiO2 without basically causing interfacial corrosion. This work demonstrates the possibility of developing a simple, low-cost and environmentally-friendly cleaning solution to effectively solve the issues of BTA removal on post-Cu CMP cleaning in a multi-layered copper wafer.

Etch characteristics of Si_(1-x)Ge_x films in HNO_3:H_2O:HF

The etch characteristics of Si_1-xGex films in HNO3:H2O:HF were examined. The etch rate ratio (etch selectivity) between Si_1-xGex and Si escalated with the growth of HNO3 concentration at low concentration level, and when the HNO3 concentration exceeded a critical level the etch selectivity descended with higher HNO3 concentration. The dependence of etch selectivity on the HNO3 concentration was due to the higher critical HNO3 concentration for etching Si than that for etching Si1-xGex. Since the Ge-Ge bond energy was weaker than that of Si-Si and Si-Ge, the Ge atoms were oxidized preferentially once the HNO3 composition exceeded the critical concentration of etching Si1-xGex,which was manifested by the XPS spectra of Si1-xGex etched in HNO3:H2O:HF. When the HNO3 volume rose to another critical value, the significant growth of the Si etch rate low-ered the etch selectivity. Although both the etch rates of Si1-xGex and Si dropped with lower HF concentration, the etch rate ra-tio of Si1-xGex to Si boosted remarkably due to the water-soluble characteristics of GeO2.

Dependence of wet etch rate on deposition,annealing conditions and etchants for PECVD silicon nitride film

The influence of deposition, annealing conditions, and etchants on the wet etch rate of plasma enhanced chemical vapor deposition （PECVD） silicon nitride thin film is studied. The deposition source gas flow rate and annealing temperature were varied to decrease the etch rate of SiNx：H by HF solution. A low etch rate was achieved by increasing the SiH4 gas flow rate or annealing temperature, or decreasing the NH3 and N2 gas flow rate. Concentrated, buffered, and dilute hydrofluoric acid were utilized as etchants for Sit2 and SiNx：H. A high etching selectivity of Sit2 over SiNx：H was obtained using highly concentrated buffered HE

The effects of ultrasound frequency and power on the activation energy in Si-KOH reaction system

The activation energy is the minimum amount of energy required to initiate a reaction. It is one of the important indexes for appraising a reaction. The chemical reaction rate is closely related to the value of activation energy, and reducing activation energy is propitious to promoting a chemical reaction. In the present paper, the relationship between the activation energy in Si-KOH reaction system and the ultrasound frequency and power has been discussed for the first time. The range of ultrasound frequency and power is 40-100kHz （interval by 20kHz） and 10-50W （interval by 10W）, respectively. The experimental clata indicate that the activation energy decreases with the increasing ultrasound power. Comparing with the activation energy without ultrasound irradiation, the results in our paper indicate that ultrasound irradiation could reduce the activation energy in Si-KOH reaction system and increase the reaction rate.