摘要:

There is considerable interest in understanding particle formation in microelectronic fabrication processes since process generated particles are a major source of yield loss in the industry. In this work, particle formation in a plasma enhanced chemical vapor deposition process has been studied using a newly developed instrument—the particle beam mass spectrometer (PBMS)—capable of measuring number densities and size distributions of submicron particles in vacuum environments with pressures>50 mTorr. Experiments have been conducted during the deposition of amorphous silicon, oxide, and nitride films, and particle formation correlated with process parameters such as plasma power and substrate temperature. For the measurements reported, the PBMS has been operated in a downstream monitoring mode, i.e., the PBMS sampled gases from the reactor exhaust during the deposition. Particle formation was observed during the amorphous silicon and oxide runs, but not during the nitride experiments. For the processes in which particle formation was observed, measured particle concentrations decreased with decreasing plasma power and increasing substrate temperature. The measured particle size distributions peaked at ∼0.09 μm for the amorphous silicon, and ∼0.04 μm for the oxide runs. The measured particle diameters compared reasonably well with values obtained from scanning electron microscope (SEM) analysis of particle samples collected on SEM stubs during deposition.

ISSN:1071-1023    

DOI:10.1116/1.589851

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The geometry of low pressure inductively coupled plasma sources is usually considered to be a main factor in determining both the plasma and processing uniformity over large area wafers. We demonstrate experimentally that the gas flow distribution can have a major impact on both the plasma density and etch rate uniformity at low pressures where one might expect diffusion to make gas flow distribution less important. 150 mm polysilicon on oxide wafers were etched inSF6/Ar(1:1) plasmas between 6 and 20 mTorr. Using a single gas inlet produced polysilicon etch rates that varied by 30% along the gas flow direction, but were highly uniform perpendicular to the gas flow direction. A gas distribution ring, on the other hand, produced highly uniform etch rates with variations less than 4% overall using the same source. Langmuir probe measurements of the ion saturation current spatial profiles in argon andSF6discharges demonstrated significant gradients across the reactor for a single gas inlet with the largest current density near the inlet.

ISSN:1071-1023    

DOI:10.1116/1.589852

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

This article describes experimental measurements and computer calculations of the location of microtrenches in the gate oxide at the periphery of a complementary metal-oxide semiconductor gate resulting from a polysilicon gate etch with a low pressure, high density plasma, etch tool. When the oxide is removed at the periphery of a gate with the etch process, it is possible to damage the underlying silicon in the source and drain regions. This damage may not be observable in scanning electron microscope pictures but could still lead to device degradation or failure. To measure the integrity of the oxide at the gate periphery, a modified MOS (MMOS) capacitor test structure was used to measure the electric field breakdown strength of the oxide at the gate periphery. The breakdown voltage can be related to the amount of remaining oxide at the gate periphery. This article describes the use of the MMOS test structure to measure the location of the microtrenches relative to the gate edge in a low pressure, high density plasma, polysilicon gate etch tool.

ISSN:1071-1023    

DOI:10.1116/1.589850

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Characteristics of selectiveSiO2etching overSi3N4in a magnetized inductively coupled high densityC4F8plasma have been investigated as a function of process parameters. TheSiO2etch rate increases with both external dc magnetic field (0–15 G) and rf discharge power at a pressure of 1.2 mTorr. ForSi3N4, the etch rate also increases with rf power at unmagnetized and weakly magnetized (6 G) plasma conditions, but it decreases with discharge power when the magnetic field is higher than 12 G. At the substrate bias voltage of −100 V, the lowest etch rate ofSi3N4is obtained at two different process conditions namely low power, unmagnetized and high power, magnetized discharges. As the pressure increases, selectivity is degraded severely due to the rapid increase in theSi3N4etch rate. Resulting selectivities varied from approximately 1:1 to 40:1 without altering the feed gas chemistry. Measurement of fluorine density and CF,CF2flux incident on the substrate reveal that the improvement ofSiO2/Si3N4etch selectivity is correlated to the rate of change of both CF andCF2radicals being greater than that of fluorine. It is also shown that the high ion current at sufficiently low fluorine density is important for high selectivity. These results imply that the high density low pressure plasma source is indeed important for the selective etching ofSiO2/Si3N4.

ISSN:1071-1023    

DOI:10.1116/1.589853

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Si3N4has been produced on GaAs with low interface trap densities by electron cyclotron resonanceN2–Heplasma assisted nitridation of a Si layer deposited on a GaAs (100) substrate. Nitridation at 150 and 400 °C was monitored by x-ray photoelectron spectroscopy (XPS) and produced stoichiometricSi3N4.The nitride layer thickness, as determined from XPS as a function of photoelectron takeoff angle, initially increased rapidly with nitridation time with a transition at a thickness of 12–18 Å to slower growth. Capacitance/voltage and conductance/angular frequency measurements were performed on metal-insulator-semiconductor capacitors fabricated from the nitrided samples. The results demonstrated interface trap densities with a minimum of3.0×1011 eV−1 cm−2when nitrided at 150 °C. At 400 °C the nitridation produced a poor quality interface, which resulted either from the higher temperature or from nitridation of all of the Si, leaving theSi3N4in direct contact with the GaAs.

ISSN:1071-1023    

DOI:10.1116/1.590300

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Inductively coupled plasma etching of GaAs/AlGaAs was investigated inBCl3/Cl2/Ar using a mixture design experiment. According to the model extracted from the experiment, the etch rate was linearly proportional to the gas flows, and the process was reactant or diffusion limited. Etch rates from 200 to over 3000 nm/min were obtained. Equirate etch was observed for AlGaAs films with different aluminum content in the entire gas composition range. A quadratic dependence was observed for the etch rates of the resist mask with the gas flows. Etched profiles ranged from positively sloped to vertical to negatively sloped depending on the gas composition. Smooth etched surfaces and mirror quality smooth sidewalls were obtained.

ISSN:1071-1023    

DOI:10.1116/1.590216

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

We have investigated the etching characteristics of InP etched with aCH3Cl/Ar/H2gas mixture with electron-cyclotron-resonance excitation and compared them with those for aCH4/Ar/H2gas mixture. Some advantages ofCH3Cl/Ar/H2over theCH4/Ar/H2are found. A smooth etched surface without etch residue is obtained at 120 °C and above. Etch residue, which is drop shaped and originates from the preferential desorption of phosphorus, is inevitably generated when theCH4/Ar/H2is used. The etch rate (15–25 nm/min at the temperatures of 120–175 °C) is larger than inCH4/Ar/H2etching. This etch rate is controllable for fine structure fabrication, such as the grating in a semiconductor laser diode, and successful fabrication of a grating with 150 nm pitch and 30 nm depth is demonstrated.

ISSN:1071-1023    

DOI:10.1116/1.589854

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Monitoring two-dimensional plasma uniformity in dry etching process by using the imaging plate has been investigated. It was found that the distribution of photostimulated-luminescence intensity of the imaging plate correlates well with the distribution of the ion density in the plasma measured with a Langmuir probe. The effect of ultraviolet light from the plasma has been investigated by covering the imaging plate with a quartz wafer. It was found that the imaging plate senses ultraviolet light from the plasma whose intensity is correlated with the ion density in the bulk plasma.

ISSN:1071-1023    

DOI:10.1116/1.589855

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

A production-scale ionized physical vapor deposition (I-PVD) source has been developed to investigate the directional metalization of 200 mm diameter wafers by sputtering. The ionization of sputtered metal is accomplished by a 45 cm diameter inductively coupled plasma (ICP). Unlike previously reported I-PVD sources, however, the coil of the ICP is external to the plasma chamber. A plasma-immersed Faraday shield is used to prevent sputtered metal from depositing on the walls of the plasma chamber and electrically shorting the ICP source. Interaction between the Faraday shield and the ICP is found to result in an rf-induced negative self-bias of no more than 15 V dc on the shield. Since the simple internal geometry of this I-PVD system is not complicated by an immersed inductor, factors that control radial uniformity are readily investigated. The spatially resolved flux of aluminum neutrals and ions on 200 mm wafers is measured and compared with two diffusion models. Both the aluminum neutral and ion density are centrally peaked with a profile that is predicted by simple diffusion in a cylindrical chamber. The fraction of ionized aluminum flux is quite uniform, however, since the aluminum neutral density and ion density radially decrease at similar rates.

ISSN:1071-1023    

DOI:10.1116/1.589856

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Ionized physical vapor deposition (IPVD) is an emerging technology for coating high aspect ratio vias and trenches for the microelectronics industry. Ionized physical vapor deposition systems typically utilize an inductive discharge generated by an internal antenna. Because the antenna is immersed in the plasma, the possibility of antenna material sputtering into the discharge is a contamination issue. In this investigation, optical emission spectroscopy is used to acquire spectra from an IPVD system to monitor the presence of antenna metal in the discharge. The observed presence of antenna material in the spectra confirms that antenna sputtering is occurring. Experimental sputter rates as determined from witness plate observations are in reasonable agreement with predictions of a simplified model of antenna sputtering, indicating that the sputtering results from large self-bias voltages on the rf antenna.

ISSN:1071-1023    

DOI:10.1116/1.589857

出版商:American Vacuum Society    

年代:1998

数据来源: AIP