Low-Temperature Processing Technology of SiC Devices

(1) 1996年的结果(a)铝原子在n型6H-SiC （n= 1.4 × 10^<18>cm^<-3>）和4H-SiC衬底中掺杂，并置于含有三甲基铝和氢混合气体的掺杂室中，压力为100 Torr。Al原子分布在50nm范围内，掺杂区在掺杂状态下表现为p型导电。孔洞浓度和迁移率分别为2-4x10^<18>cm^<-3>，1-2x10^2cm^2/Vsec和2-4x10^<18>cm^<-3>,70-100cm^2/Vsec。(b)利用KrF准分子激光在n型6H-SiC衬底（n= 1.5 × 10^<18>cm^<-3>）上沉积Ni-欧姆电极。采用激光能量密度1.0J/cm^2、1000个脉冲的室温工艺制备了深120nm的ni掺杂层。接触电阻率估计为6x10^<-3> ω ^2。(c)采用KrF准分子激光辐照工艺，在三甲基硼和氢的混合气体中对n型6H-SiC衬底进行了硼掺杂研究。在激光能量密度为0.8J/cm^2，激光发射次数为1000 ~ 5000次的条件下，SIMS分析表明B原子的掺杂范围为10 ~ 20 nm。(d)在n型6H-SiC （n= 1.8 × 10^<18>cm^<-3>）衬底上，利用激光烧蚀W颗粒（纯度99.9%）和KrF准分子激光掺杂沉积W，制备了在1000‰（2小时）下稳定的钨欧姆触点。在衬底上形成的10-20 nm深的浅触点和突然触点在未经热处理的情况下表现出良好的欧姆特性（接触电阻率2.2x10^<-4>OMEGAcm^2）。在能量密度为2.0J/cm^2的激光照射下，其表面仍非常光滑。

(1) Results in 1996(a) Aluminum atoms have been doped in n type 6H-SiC (n= 1.4x10^<18>cm^<-3>) and 4H-SiC substrates set in doping chamber containing mixed gases of tri-methyl aluminum and hydrogen with a pressure of 100 Torr. Al atoms are distributed in the range of 50 nm, and the doped region showed p type conduction in as-doped conditions. Hole concentration and the mobility are estimated to be 2-4x10^<18>cm^<-3>,1-2x10^2cm^2/Vsec, and 2-4x10^<18>cm^<-3>,70-100cm^2/Vsec, respectively.(b) Ni-ohmic electrodes have been fabricated on n-type 6H-SiC substrates (n= 1.5x10^<18>cm^<-3>) by KrF excimer laser irradiation during Ni deposition. A shallow Ni-doped layr 120nm deep was formed by room temperature processes (laser energy density 1.0J/cm^2 and 1,000 pulses). Contact resistivity was estimated to be 6x10^<-3>OMEGAcm^2.Results in 1997(c) Boron-doping has been examined in n-type 6H-SiC substrates set in the gas mixture of tri-methyl boron and hydrogen by using KrF excimer laser irradiation processes. Inconditions of the laser energy density 0.8J/cm^2 and number of laser shots 1000-5000, SIMS analysis shows B atoms are doped in the range of 10-20 nm. P-type conduction with Hall measurements has not been assured due to shallow depth of the doped region(d) Tungsten ohmic contacts stable at 1000ﾟC (2 hours) have been fabricated on n-type 6H-SiC (n= 1.8x10^<18>cm^<-3>) substrates using both laser ablation of W pellets (purity 99.9%), and laser doping of deposited W with a KrF excimer laser inthe same process chamber. Shallow and abrupt contacts formed 10-20 nm deep in the substrates showed good ohmic characteristics without post-heat treatments (contact resistivity 2.2x10^<-4>OMEGAcm^2). The surface was found to be very smooth even after laser irradiation of the energy density 2.0J/cm^2.