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We demonstrated a coverage-controllable sidewall protective film by controlling the degree of oxidation during plasma-enhanced SiO2 atomic layer deposition (ALD) as a novel technology to suppress bowing in a high-aspect-ratio-contact (HARC) hole etch process. By depositing SiO2 protective film with atomic order on only the top-local region of patterns, to suppress bowing was achieved during HARC etch without the shrinkage of the bottom critical dimension (CD) and etch-stop. In addition, we investigated the parameters that determine the ALD coverage to estimate the coverage profile of sidewall protective film. By analyzing the relationship between activation time and ALD film thickness at each AR, we confirmed that the coverage is determined by the transport of oxygen radical based on the Knudsen transport model. Furthermore, we developed an ALD simulator from the transport model, and successfully estimated the coverage of protective film during etching to improve the verticality of the HARC profile with small bowing-bottom CD bias.

We demonstrated a high selective and anisotropic plasma etch of Si3N4 and SiC. The demonstrated process consists of a sequence of ion modification and chemical dry removal steps. The Si3N4 etch with H ion modification showed a high selectivity to SiO2 and SiC films. In addition, we have developed selective etch of SiC with N ion modification. On the other hand, in the patterning etch processes, the fabrication of multi-layer films requires the precision of atomic scale XY CD controllability in complex hole patterns. In order to solve the requirement, we have developed Advanced Quasi- Atomic Layer Etching (ALE) technology which achieved X-Y CD control in oval patterns, along with a wider X-Y CD control margin. Furthermore, in the memory fabrication process, it is required to vertically etch the organic film mask pattern in high aspect ratio (A/R) feature. Therefore, we have developed a new approach that combines atomic layer deposition (ALD) technique and organic film etch process. With this method, we are able to achieve the vertical mask profile. Thus, we will show that these new process technologies have a significant potential to solve critical challenges in the various processes in advanced nodes.

We demonstrated a high selective and anisotropic plasma etch of silicon nitride (Si3N4) and silicon carbide (SiC). The demonstrated process consists of a sequence of ion modification and chemical dry removal steps. The Si3N4 etch with hydrogen (H) ion modification showed a high selectivity to silicon dioxide (SiO2) and SiC films without hydro fluorocarbon film deposition which has been used in a conventional Si3N4 etch process. A self-limiting reaction was observed by changing the ion modification and removal step times. The SIMS analyzes indicated that the etch amount of Si3N4 depends on not only penetration depth of H ion but also H concentration in the ion modification step. In addition, we have developed selective etch of SiC with nitrogen (N) ion modification. These results suggest that the ion modification assisted etch enables us to obtain the high selective Si3N4 or SiC film by H or N ion modification, respectively.

A new tandem type source has been constructed on the basis of electron cyclotron resonance plasma for producing synthesized ion beams in Osaka University. Magnetic field in the first stage consists of all permanent magnets, i.e., cylindrically comb shaped one, and that of the second stage consists of a pair of mirror coil, a supplemental coil and the octupole magnets. Both stage plasmas can be individually operated, and produced ions in which is energy controlled by large bore extractor also can be transported from the first to the second stage. We investigate the basic operation and effects of the tandem type electron cyclotron resonance ion source (ECRIS). Analysis of ion beams and investigation of plasma parameters are conducted on produced plasmas in dual plasmas operation as well as each single operation. We describe construction and initial experimental results of the new tandem type ion source based on ECRIS with wide operation window for aiming at producing synthesized ion beams as this new source can be a universal source in future.

A new tandem type source of electron cyclotron resonance (ECR) plasmas has been constructing for producing synthesized ion beams in Osaka University. Magnetic mirror field configuration with octupole magnets can be controlled to various shape of ECR zones, namely, in the 2nd stage plasma to be available by a pair mirror and a supplemental coil. Noteworthy correlations between these magnetic configurations and production of multicharged ions are investigated in detail, as well as their optimum conditions. We have been considering accessibility condition of electromagnetic and electrostatic waves propagating in ECR ion source plasma, and then investigated their correspondence relationships with production of multicharged ions. It has been clarified that there exits efficient configuration of ECR zones for producing multicharged ion beams experimentally, and then has been suggested from detail accessibility conditions on the ECR plasma that new resonance, i.e., upper hybrid resonance, must have occurred.

With the miniaturization of semiconductors, the technology of shallow junctions becomes important. As shallow junctions advance, ion implantation by using ion beams at low energy with good control is needed. An electron cyclotron resonance ion source (ECRIS) can efficiently generate a high-density plasma at low pressure and a high intensity ion beam. In our ECRIS, the wide operation of various ion beam is available from deeper implantation of multi-charged ions at high energy to shallow junction at very low energy. However, a potential and a sheath near the wall are formed with an ECR plasma, because ECRIS is a volume source. Therefore, the potential affects the control of the ion beam at very low energy. In this study, we measure the potential by using the ion beam extracted from the ECRIS. In addition, we confirm that the potential by using the ion beam method correlates with electron temperature when microwave power and pressure change in ECRIS.

A tandem-type electron cyclotron resonance (ECR) ion source (ECRIS) has been constructed for synthesizing, extracting, and analyzing ions. The feasibility and realization of the device which has rangy operation window in a single device are investigated to produce many kinds of ion beams like universal source based on ECRIS. The ECR plasmas are considered to be necessary to be available to coexist and to be operated individually with different plasma parameters. Both of analysis of ion beams and investigation of plasma parameters will be conducted on produced plasmas. In this article the experimental study concentrates on improvement of producing and extracting multicharged ion beams from the second stage of the tandem-type ECRIS under lower magnetic mirror field with octupole magnets. The assembly of the extractor is modified and their positions, gap, and potentials are investigated against each ion spices. We succeeded in producing, extracting multicharged ion currents and improving ion extraction, while the magnetic field is about 60% of the previous magnetic field strength. We will present obtained evidences experimentally in detail.

A new concept on magnetic field of plasma production and confinement has been proposed to enhance efficiency of an electron cyclotron resonance (ECR) plasma for broad and dense ion beam source under the low pressure. We make this source a part of new tandem type ion source for the first stage. We are also constructing the large bore second stage for synthesizing, extracting and analyzing ions. Both ECR plasmas are necessary to be available to coexist and to be operated individually with different plasma parameters. In the first stage, we optimize the ion beam current and ion saturation current by a mobile plate tuner. They change by the position of the plate tuner for single and multi-frequencies microwaves. The peak positions of them are close to the position where the microwave mode forms standing wave between the plate tuner and the extractor. We show a new guiding principle, which the number of efficiently azimuthal microwave mode should be selected to fit to that of multipole of comb-shaped magnets. We obtained the excitation of selective modes using new mobile plate tuner to enhance ECR efficiency. Furthermore we first obtained charge state distributions of ion beams extracted from the first stage after constructing the second stage and its beam line.

Multi-charged ion source which has wide operating conditions is required in various application fields. We have constructed tandem type ECR ion source (ECRIS); one of the features of its main stage is an additional coil for controlling magnetic field distribution around the mirror bottom precisely. Here the effect of magnetic field variation caused by the additional coil is experimentally considered in terms of plasma parameters and beam current as the first investigation of the main stage plasma. Furthermore, behavior of magnetic lines of force flowing from the ECR zone is calculated, and is compared with measurement results aiming for better understanding of interrelationship between plasma production and ion beam generation on the ECRIS.

We are constructing a tandem type electron cyclotron resonance (ECR) ion source (ECRIS). High-energy electrons in ECRIS plasma affect electron energy distribution and generate multicharged ion. In this study, we measure electron energy distribution function (EEDF) of low energy region (≦100 eV) in ECRIS plasma at extremely low pressures (10(-3)-10(-5) Pa) by using cylindrical Langmuir probe. From the result, it is found that the EEDF correlates with the electron density and the temperature from the conventional probe analysis. In addition, we confirm that the tail of EEDF spreads to high energy region as the pressure rises and that there are electrons with high energy in ECR multicharged ion source plasma. The effective temperature estimated from the experimentally obtained EEDF is larger than the electron temperature obtained from the conventional method.

A new tandem type source has been constructed on the basis of electron cyclotron resonance (ECR) plasma for producing synthesized ion beams. We investigate feasibility and hope to realize the device which has wide range operation window in a single device to produce many kinds of ion beams based on ECR ion source (ECRIS). It is considered that ECR plasmas are necessary to be available to individual operations with different plasma parameters. Both of analysis of ion beams and investigation of plasma parameters are conducted on produced plasmas. We describe construction of the new tandem type ion source based on ECRIS with wide operation window for aiming at producing synthesized ion beams as this new source can be a universal source.

We are constructing a tandem type ECRIS. The first stage is large-bore with cylindrically comb-shaped magnet. We optimize the ion beam current and ion saturation current by a mobile plate tuner. They change by the position of the plate tuner for 2.45 GHz, 11-13 GHz, and multi-frequencies. The peak positions of them are close to the position where the microwave mode forms standing wave between the plate tuner and the extractor. The absorbed powers are estimated for each mode. We show a new guiding principle, which the number of efficient microwave mode should be selected to fit to that of multipole of the comb-shaped magnets. We obtained the excitation of the selective modes using new mobile plate tuner to enhance ECR efficiency.