텅스텐 실리사이드 산화시 발생하는 이상산화 현상 억제에 미치는 이온 주입 효과

이재갑(Jaegab Lee),노재성(Jaesung Roh),이정용(Jeongyong Lee) 한국진공학회(ASCT) 1994 Applied Science and Convergence Technology Vol.3 No.3

다결정 실리콘 위에 저압 화학 증착법으로 비정질 WSix 를 증착시킨 후에 질소 분위기, 870℃ 온도에서 2시간 동안 열처리를 실시하여 결정화를 이룩한 다음, 표면의 산화막을 희석된 불산용액으로 제거한 후 산화를 실시하면 이상산화막이 형성이 되었다. 이와 같은 이상 산화막 형성은 산화 공정전에 P 또는 As 이온 주입을 실시함으로써 억제되고 있었으며, P이온 주입 처리가 As 이 온주입보다 이상산화막 발생 억제에 보다 효율적임이 확인되었다. P이온 주입 처리가 보다 효과적인 것은 산화시 산화막내에 형성되는 P₂O_5 가 산화막의 용융점을 크게 낮추어 양칠의 산화막을 형성하는 데 기인하는 것으로 여겨진다. 마지막으로 이온 주입 처리에 의하여 비정질화된 텅스텐 실리사이드 표면의 산화 기구에 대하여 제안하였다. Oxidation of the crytalline tungsten silicide caused the growth of the abnormal oxide over WS₂. High dose ion implantation into the silicide surface prior to oxidation was revealed to be effective to suppress the formation of abnormal oxide. Compared with using arsenic, the use of phosphorous ion implantation produced thinner oxide, which was probably due to the formation of P₂O_5 in the oxide layer during the oxidation. The presence of P₂O_5 in the oxide dramatically decreased the oxide melting temperature, thereby facilitating the growth of the uniform and high quality SiO₂. Finally, the mechanism for the oxidation of the tungsten silicide surface, amorphized by using high dose ion implantation prior to oxidation, was proposed.

PECVD of Blanket TiSi₂ on Oxide Patterned Wafers

이재갑(Jaegab Lee) 한국진공학회(ASCT) 1992 Applied Science and Convergence Technology Vol.1 No.1

C_(54)Ti-silicide(TiSi₂)의 증착 온도를 낮추고 챔버내에서 표면처리를 가능하게 하기 위하여 플라즈마를 고진공장치에 부착시켰다. SiH₄와 TiCl₄를 이용하여 증착시킨 Ti-silicide는 14~25 uohm-㎝의 낮은 저항을 가지고 있었다. 실험변수가 silicide의 성장속도와 이 때 발생하는 기판 실리콘의 소모(Silicon Consumption)에 미치는 영향에 대한 연구는 SiH₄가 실리사이드 형성에 참여하는 주요한 성분이며, 기판 실리콘은 silicide 형성에 참여하지 않고 소모됨을 보여주고 있었다. 또한 실리콘 소모에 주요한 영향을 미치는 인자는 가스조성과 증착온도였다. SiH₄를 6 sccm에서 9 sccm으로 증가시켰을 경우는 실리콘 소모가 1500 Å/min에서 30 Å/min 이하로 감소하였고, 온도를 650℃에서 590℃로 낮추었을 경우에는 실리콘 소모가 일어나지 않고 균일한 두께의 TiSi₂가 형성되었다. 마지막으로 기판 실리콘 소모에 SiH₄가 미치는 영향을 이해하기 위하여 실리콘 소모에 대한 반응 모델을 고려하였다. A plasma has been used in a high vaccum, cold wall reactor for low temperature deposition of C_(54) TiSi₂ and for in-situ surface cleaning prior to silicide deposition. SiH₄ and TiCl₄ were used as the silicon and titanium sources, respectively. The deposited films had low resistivities in the range of 15~25 uohm-cm. The investigation of the experimental variables' effects on the growth of silicide and its concomitant silicon consumption revealed that SiH₄ and TiCl₄ were the dominant species for silicide formation and the primary factors in silicon consumption were gas composition ratio and temperature. Increasing silane flow rate from 6 to 9 sccm decreased silicon consumption from 1500 A/min to less than 30 A/min. Furthermore, decreasing the temperature from 650 to 590℃ achieved blanket silicide deposition with no silicon consumption. A kinetic model of silicon consumption is proposed to understand. the fundamental mechanism responsible for the dependence of silicon consumption on SiH₄ flow rate.

Cu(B)/Ti/SiO₂ 구조를 열처리할 때 일어나는 미세구조 변화에 미치는 Ti 하지층 영향

이재갑,Lee Jaegab 한국재료학회 2004 한국재료학회지 Vol.14 No.12

Annealing of $Cu(B)/Ti/SiO_2$ in vacuum has been carried out to investigate the effects of Ti underlayer on microstructure in $Cu(B)/Ti/SiO_2$ structures. For comparison, $Cu(B)/Ti/SiO_2$ structures was also annealed in vacuum. Three different temperature dependence of Cu growth can be seen in $Cu(B)/Ti/SiO_2$; B precipitates- pinned grain growth, abnormal grain growth, normal grain growth. The Ti underlayer having a strong affinity for B atoms reacts with the out-diffused B to the Ti surface and forms titanium boride at the Cu-Ti interface. The formation of titanium boride acts as a sink for the out-diffusion of B atoms. The depletion of boron in grain boundaries of Cu films, as results of the rapid diffusion of B along the grain boundaries and the insufficient segregation of B to the grain boundaries, induces grain boundaries to migrate and causes the abnormal grain growth. The increased bulk diffusion coefficient of B within Cu grains can be responsible for the normal grain growth occurring in the annealed $Cu(B)/Ti/SiO_2\;at\;600^{\circ}C$. In contrast, the $Cu/SiO_2$ structures show only the abnormal growth of grains and their sizes increasing as the temperature increases above $400^{\circ}C$.

TFT-LCDs 게이트 전극에 적용한 Cu(Mg) 합금 박막의 건식식각

양희정,이재갑,Yang Heejung,Lee Jaegab 한국재료학회 2004 한국재료학회지 Vol.14 No.1

The annealing of a Cu(4.5at.% Mg)/$SiO_2$/Si structure in ambient $O_2$, at 10 mTorr, and $300-500^{\circ}C$, allows for the outdiffusion of the Mg to the Cu surface, forming a thin MgO (15 nm) layer on the surface. The surface MgO layer was patterned, and successfully served as a hard mask, for the subsequent dry etching of the underlying Mg-depleted Cu films using an $O_2$ plasma and hexafluoroacetylacetone [H(hfac)] chemistry. The resultant MgO/Cu structure, with a taper slope of about $30^{\circ}C$ shows the feasibility of the dry etching of Cu(Mg) alloy films using a surface MgO mask scheme. A dry-etched Cu(4.5at.% Mg) gate a-Si:H TFT has a field effect mobility of 0.86 $\textrm{cm}^2$/Vs, a subthreshold swing of 1.08 V/dec, and a threshold voltage of 5.7 V. A novel process for the dry etching of Cu(Mg) alloy films, which eliminates the use of a hard mask, such as Ti, and results in a reduction in the process steps is reported for the first time in this work.

차세대 공정에 적용 가능한 Cu(B)/Ti/SiO₂/Si 구조 연구

이섭,이재갑,Lee Seob,Lee Jaegab 한국재료학회 2004 한국재료학회지 Vol.14 No.4

We have investigated the effects of boron added to Cu film on the Cu-Ti reaction and microstructural evolution of Cu(B) alloy film during annealing of Cu(B)/Ti/$SiO_2$/Si structure. The result were compared with those of Cu(B)/$SiO_2$ structure to identify the effects of Ti glue layers on the Boron behavior and the result grain growth of Cu(B) alloy. The vacuum annealing of Cu(B)/Ti/$SiO_2$ multilayer structure allowed the diffusion of B to the Ti surface and forming $TiB_2$ compounds at the interface. The formed $TiB_2$ can act as a excellent diffusion barrier against Cu-Ti interdiffusion up to $800^{\circ}C$. Also, the resistivity was decreased to $2.3\mu$$\Omega$-cm after annealing at $800^{\circ}C$. In addition, the presence of Ti underlayer promoted the growth Cu(l11)-oriented grains and allowed for normal growth of Cu(B) film. This is in contrast with abnormal growth of randomly oriented Cu grains occurring in Cu(B)/$SiO_2$ upon annealing. The Cu(B)/Ti/$SiO_2$ structure can be implemented as an advanced metallization because it exhibits the low resistivity, high thermal stability and excellent diffusion barrier property.

수소 환원기체와 (hfac)Cu(3,3-dimethyl-1-butene) 증착원을 이용한 Pulsed MOCVD로 Cu seed layer 증착 특성에 미치는 영향에 관한 연구

박재범,이진형,이재갑,Park Jaebum,Lee Jinhyung,Lee Jaegab 한국재료학회 2004 한국재료학회지 Vol.14 No.9

Pulsed metalorganic chemical vapor deposition (MOCVD) of conformal copper seed layers, for the electrodeposition Cu films, has been achieved by an alternating supply of a Cu(I) source and $H_2$ reactant at the deposition temperatures from 50 to $100^{\circ}C$. The Cu thickness increased proportionally to the number of cycles, and the growth rate was in the range from 3.5 to $8.2{\AA}/cycle$, showing the ability to control the nano-scale thickness. As-deposited films show highly smooth surfaces even for films thicker than 100 nm. In addition about a $90\%$ step coverage was obtained inside trenches, with an aspect ratio greater than 30:1. $H_2$, introduced as a reactant gas, can play an active role in achieving highly conformal coating, with increased grain sizes.

Cu(Mg) alloy의 산화방지막 형성에 영향을 미치는 인자

조흥렬(Heunglyul Cho),조범석(Beomseok Cho),이원희(Wonhee Lee),이재갑(Jaegab Lee) 한국진공학회(ASCT) 2000 Applied Science and Convergence Technology Vol.9 No.2

Cu (4.5 at. % Mg) target을 이용하여 sputtering에 의해 증착된 Cu(Mg) alloy 박막의 열처리시 형성되는 산화 방지막 MgO의 박막 특성에 영향을 주는 인자에 대해 살펴보았다. MgO 박막의 산화방지 능력 및 막질에 영향을 주는 인자로는 열처리 온도, O₂ 압력, Mg 농도 등으로 나타났다. MgO 박막의 두께는 열처리 온도가 증가함에 따라 증가하다 500℃ 이상에서는 150 Å 정도의 성장한계두께를 나타내었다. 표면에 형성되는 MgO 박막은 O₂ 압력이 낮을수록, Mg의 농도가 높을수록 치밀한 MgO가 형성되어 산화방지에 우수한 특성을 보였으며 전 열처리 과정인 진공 열처리 공정은 lat.% 정도의 낮은 Mg 농도에서도 치밀한 MgO 형성에 매우 효과적임이 확인되었다. 본 연구에서 Cu(Mg) alloy 박막의 열처리를 통해 낮은 저항의 Cu박막의 형성과 동시에 산화방지에 우수한 특성을 보이는 MgO 박막을 열처리 온도, O₂ 압력, Mg 농도등의 최적조건을 이용하여 얻어질 수 있음을 확인하였다. Variables affecting the passivation capability of Cu(Mg) alloy films, which were sputter deposited from a Cu (4.5 at. %) target, have been investigated. The results show that the passivation capability of a Cu(Mg) alloy film is a function of annealing temperature, O₂ pressure, and Mg content in the film. Increasing the annealing temperature up to 500℃ favors formation of a dense MgO layer on the surface which has a growth limited thickness of 150 Å. Decreasing the O₂ pressure enhances the preferential oxidation of Mg over Cu. Furthermore, increasing the Mg content in the Cu(Mg) film promotes formation of a dense MgO layer. Vacuum pre-annealing was found to be very effective in segregating Mg to the surface, facilitating the passivation capability of the Cu(Mg) alloy film even when the Mg content is low. In the current study, self-aligned MgO layers with low resistivity and an effective passivation capability over the Cu surface, have been obtained by manipulating these factors when Cu(Mg) thin films are annealed.

Ag agglomeration에 대한 연구

홍성진,이재갑 국민대학교 생산기술연구소 2002 공학기술논문집 Vol.25 No.-

Ag-alloy films have been investigated as interconnect materials applicable to thin film transistor liquid crystal displays (TFT-LCDs). Pure silver films deposited on SiO₂ and glass by DC magnetron sputtering,showed severe hillock formation, hole growth, and agglomeration upon annealing in air. On the other hand, APC Ag films, alloyed with 0.9 at.% of Pd and 1.7 at.% of Cu and Ag(5 at.% Mg) alloy films, showed enhanced resistance to agglomeration.