Etching mechanisms of HfO2, SiO2, and poly-Si substrates in BCl3 plasmas

BCl3 based plasmas exhibit promising plasma chemistries to etch high-k materials and, in particular, HfO2, with a high selectivity over SiO2 and Si substrates. The authors report on the mechanisms involved in the etching of HfO2, SiO2, and poly-Si substrates in BCl3 plasmas. X-ray photoelectron spectroscopy analyses help in understanding the mechanism driving the high etch selectivity between HfO2 and silicon-containing substrates. The ion energy plays an important role in the etching mechanisms since it controls a transition between a BCl-like deposition on the substrate and its etching by ionic bombardment. The ion energy threshold above which etching occurs is different from one substrate to another, being lower for HfO2 than for Si substrates. Indeed, BClx deposition forms more easily on poly-Si or SiO2 rather than on HfO2 surfaces, because boron reacts with Si atoms to form Si–B bonds initiating the growth of BClx polymer on Si-containing surfaces, while on HfO2 surfaces, boron is directly involved i...

[1]  Kazuo Takahashi,et al.  Etching of High-k Dielectric HfO2 Films in BCl3-Containing Plasmas Enhanced with O2 Addition , 2006 .

[2]  V. M. Donnelly,et al.  Etching of high-k dielectric Zr1−xAlxOy films in chlorine-containing plasmas , 2001 .

[3]  T. Chevolleau,et al.  Plasma etching of HfO2 at elevated temperatures in chlorine-based chemistry , 2006 .

[4]  J. Chinn,et al.  EVALUATION OF PLASMA CHARGING DAMAGE DURING POLYSILICON GATE ETCHING PROCESS IN A DECOUPLED PLASMA SOURCE REACTOR , 1998 .

[5]  Han-Young Lee,et al.  Selective plasma etching of ZrOx to Si using inductively coupled BCl3∕C4F8 plasmas , 2006 .

[6]  Jane P. Chang,et al.  Plasma etching of high dielectric constant materials on silicon in halogen chemistries , 2004 .

[7]  Satoshi Hamaguchi,et al.  Molecular dynamics simulation of silicon and silicon dioxide etching by energetic halogen beams , 2001 .

[8]  Jane P. Chang,et al.  Ion-enhanced chemical etching of HfO2 for integration in metal–oxide–semiconductor field effect transistors , 2003 .

[9]  Jane P. Chang,et al.  Plasma etching selectivity of ZrO2 to Si in BCl3/Cl2 plasmas , 2003 .

[10]  David P. Norton,et al.  Etch characteristics of HfO2 films on Si substrates , 2002 .

[11]  B. Shore,et al.  Etch‐stop characteristics of Sc2O3 and HfO2 films for multilayer dielectric grating applications , 1996 .

[12]  I. Bello,et al.  Mechanism of cleaning and etching Si surfaces with low energy chlorine ion bombardment , 1994 .

[13]  V. M. Donnelly,et al.  On the constant composition and thickness of the chlorinated silicon surface layer subjected to increasing etching product concentrations during chlorine plasma etching , 1999 .

[14]  Kouichi Ono,et al.  Plasma etching of high-k and metal gate materials , 2006 .

[15]  K. Torii,et al.  Selective Dry Etching of HfO2 in CF4 and Cl2/HBr-Based Chemistries , 2004 .

[16]  D. Chan,et al.  Investigation of etching properties of HfO based high-K dielectrics using inductively coupled plasma , 2004 .

[17]  J. Coburn.  Ion‐assisted etching of Si with Cl2: The effect of flux ratio , 1994 .

[18]  Jane P. Chang,et al.  Ion-enhanced chemical etching of ZrO2 in a chlorine discharge , 2002 .