Sung-yoon Kim

Cyclic technique for the enhancement of highly oriented diamond film growth

Abstract Diamond films have been deposited on (100) Si substrates through carburization, nucleation and growth steps using a microwave plasma-enhanced chemical vapor deposition system. The surface morphologies of the films were investigated as a function of the carburization time. It is likely that the ball-like agglomerates observed on the carburized surface act as nucleation sites for diamond. We also found that the density of agglomerates is not dependent on the carburization time, but their size increases with increasing carburization time. A cyclic process was applied during either the nucleation or the growth step. In general, the cyclic process leads to a decrease in the density of large agglomerates produced during the carburization step. Furthermore, the {100}-oriented texture growth is enhanced and the coverage area is increased by applying the cyclic process during nucleation.

Effect of cyclic process on the {100}‐oriented texture growth of diamond film

The {100}‐oriented texture growth of diamond film on (100) Si substrates (1×1 cm2) has been achieved by a three‐step procedure (carburization→nucleation→growth) in a microwave‐ plasma‐enhanced chemical vapor deposition (MPECVD) system. The surface morphology is found to be strongly affected by the cyclic process applied during the nucleation step. Furthermore, the density of {100}‐oriented grains as well as the coverage area are enhanced by the application of the cyclic process merely during the nucleation step. We also observed the increase in the nucleation density by the cyclic process. This increase may be the origin for the increase in the density of the {100}‐oriented grains.

Enhancement of diamond thin film quality by a cyclic deposition method under MPECVD

Abstract Diamond thin films were deposited by a cyclic deposition method, which can be carried out periodically on and off the methane gas flow in the CH 4 -H 2 system, using a microwave plasma enhanced chemical vapour deposition system. The property of diamond thin films deposited using the cyclic process was investigated and compared with that of the normal process. The quality of the diamond films deposited by the cyclic process is better than that by the normal process under the same conditions, although the growth rate of diamond film was lower in the cyclic process. However, introducing the interlayer on silicon substrate prior to the cyclic process leads to the increase in the growth rate which is comparable with that in the normal process while maintaining the same high quality of the films.

Deposition of white diamond thin films by increasing the total pressure in a microwave-plasma-enhanced chemical vapour deposition system

Abstract White diamond films, which should be composed of almost pure diamond grains, have been successfully obtained at high pressure (above 150 Torr) by microwave-plasma-enhanced chemical vapour deposition. The characteristics of the films have been examined using scanning electron microscopy and Raman spectroscopy. As the total pressure and microwave power increase, the film quality is enhanced and the film morphology changes. The film quality is found to be closely associated with the variation in the gas components in the plasma. The variation in the surface morphology of the films with total pressure is related to the substrate temperature. Transmission electron microscopy results reveal that an α-SiC interface layer forms prior to the growth of the diamond films at 60 Torr.

Effect of the cyclic growth/etching time ratio on the [lcub]100[rcub]-oriented texture growth of a diamond film

Abstract The growth of a diamond film with [lcub]100[rcub]-oriented texture on Si substrates (1×1 cm 2 ) has been achived by a three-step process (carburization → nucleation → growth) in a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system. We employed a cyclic technique in the nucleation step together with the various etching time intervals in the cyclic process. The properties of the diamond film were found to be strongly dependent on the etching time interval in the cyclic process. After the nucleation step. we investigated in the detail the state of the sample surface. Based upon these results, we discuss the effect of etching time interval on the properties of diamond films, particularly on the [lcub]100[rcub]-oriented texture growth.

Enhancement of diamond film uniformity in a biased microwave-plasma-enhanced chemical vapor deposition system

Abstract Diamond films were deposited on (1 0 0) Si substrates (1 × 1 cm 2 ) using a microwave-plasma-enhanced chemical vapor deposition (MPECVD) system. The {1 0 0}-oriented texture growth of diamond film has been achieved by three-step procedure (carburization → nucleation → growth). We found that the morphology and the uniformity of the as-deposited film vary from position to position on the substrate. The application of a cyclic method in the nucleation step leads to an increase in the density of {1 0 0}-oriented grains as well as film uniformity. The surface morphologies, diamond qualities, and microstructures of the films have been investigated. Reason for the enhancement of the film uniformity and the increase in the density of the {1 0 0}-oriented grains are discussed.

Enhancement of heat dissipation in well-faceted {{100}} diamond thin film

Abstract We measured the surface temperature of diamond films which had different morphologies from the intensity ratio of anti-Stokes to Stokes Raman lines for each laser power. Raman spectra show that the film having {{111}} morphology (after 21 h deposition) has the best diamond quality in this work. However, the measured surface temperature of well-faceted {{100}} morphology was found to be lowest among those of any other morphologies in this work, where heating was performed by the probing laser beam itself. Furthermore, the temperature rise with increasing laser power was found to be lowest in the film with well-faceted {{100}} morphology. From these results, it can be suggested that the film with well-faceted {{100}} morphology has the highest thermal conductivity.

From WLR to product reliability and qualifications in the 3D transistor era

Reliability mechanisms associated with HK+MG transistors including latest FinFETs on 14nm technology node will be discussed along with circuit and product implications on reliabilty stresses and qualifications. Reliability efforts made at the transistor module level to circuit, IP blocks, and finally to a product level reliability will be discussed and limiting mechanisms and examples will be highlighted. As part of the product qual strategy, high-speed HTOL and Set level tests were leveraged to signficantly lower product dpms and seamless introduction of high volume manufacturing.

Improving the NBTI characteristics of long-channel PMOSFETs by short channel with source underlap structure

Recently long-channel PMOS transistors are being used in delay circuits to increase delay time. Negative Bias Temperature Instability (NBTI) has channel length dependency which shows that long-channel devices degrade more than short channel devices. We suggest a source underlap structure with short channel transistor to solve this problem. We confirmed the short-channel device with underlap structure shows improved NBTI characteristics compared to normal long-channel device through a device simulation.

A Study on Contact Resistance Failure Between Al-Ti-TiN Multi-Layer and W-Via Caused by Hillock Formation

We studied how hillock in Al film increases the contact resistance (RC) between bottom-side metal stacked (Al-Ti-TiN) and upper-side W-via-plugs in the backend-structure of the semiconductor. The general structure is the via-etch-stop-on-TiN (VEST), otherwise the via-etch-stop-on-Al (VESA) was observed on the hillocks. After metal etching, the sputtering as well as the deposition (DEPO) is conducted for IMD gap-filling in the FSG process. The sputtering makes the TiN surface with the hillock cliffy and the TiN cannot take a role of the Al capping layer from via etching. We found that the oxidation of Al below recessed TiN is the main cause of the high RC. To prevent the hillock, the metal DEPO temperature is increased and the temperature of metal-etch-mask-oxide is decreased. Furthermore, the thickness of TiN increased for relieving clipping from the FSG process. Thanks to those actions, we could completely overcome the high RC issue caused by the hillock.