Sapphire(α-Al2O3) single crystals are widely used in many areas because of the special properties. As an important photoconducting device substrate material, stringent surface quality requirements are required. The use of CMP technique can produce high quality surface finishes at low cost and with fast material removal rates. In this paper, the polishing mechanism was studied. According to Arrhenius equation, temperature is the important factor of influencing chemical reaction rate. So the chosen temperature was 45°. SiO2 sol was chosen as abrasive, and the particle size is 40nm. For ensuring the stability of abrasive and chemical action of polishing slurry, the pH value was determined at 11.5~12. After polishing and cleaning the sapphire surface, the measured removal rate was above 11μm /h and the surface roughness was Ra 0.3nm. From the results, it was found that using such method, the optimal sapphire surface can be gotten.
Along with the feature size reducing and the increase of integration level rapidly in ULSI，the request for metal impurities contamination on silicon substrate surface appears specially rigorous. In this paper the chelating agent was added in cleaning solution in order to removing copper ion. FA/O, a new kind of chelating agent was studied in RCA cleaning solutions, which has 13 chelating rings and is free of sodium, stable and easily soluble. The XPS and GFAAS measured results indicate that FA/O is more efficient than NH4OH as a ligand. Cu contaminations on silicon wafer can be removed remarkably when adding a little FA/O to the cleaning solution or polishing slurry. When the chelating agent concentration of cleaning solution is 0.1% the removal rate of Cu atom reaches 83 percent. The FA/O chelating agent substituting NH4OH in SC-1 may simplify cleaning steps, and one cleaning step can remove Cu pollution on silicon wafer surface and meet the requirements of microelectronics technology.
The influence of three kinds of guanidinium salt on the removal rate selectivity of different materials was studied during the barrier chemical mechanical polishing (CMP) process at first. The three kinds of guanidine saltguanidine hydrochloride, guanidine nitrate and guanidine carbonate. Then we compared the effect of the three kinds of guanidine salt on the dishing, erosion and surface roughness value. In the end, the reaction mechanism was studied through electrochemical analysis. All the results indicate that there is a better performance of the slurry with guanidine hydrochloride than the slurries with the other two kinds of guanidine salt. It effectively improved the removal rate selectivity and the surface roughness under the premise of low abrasive concentration and low polishing pressure, which is good for the optimization of the alkaline slurry for the barrier CMP process.
Chemical mechanical polishing (CMP) process is widely used on GLSI multilayer metallization planarization which requires the highest precision atomic surface. In order to improve the removal rate and surface quality of sapphire substrate, CMP method was used and a novel pH regulator Sr(OH)2 was investigated. According to c/a/r-plane sapphire CMP experimental results good surface quality and higher material removal rate (MRR) were obtained by using the Sr(OH)2 solution as pH regulator comparing with traditional KOH as pH regulator. Meanwhile, it indicated Sr(OH)2 cannot only replace the traditional pH regulators, but also not introduce other metal ions contamination for sapphire CMP. According to the chemical thermodynamics basic principles, the trend and products of chemical reaction between sapphire and traditional water-based SiO2 slurry and between sapphire and Sr(OH)2 was analyzed by using HSC software. In addition, the action mechanism of Sr(OH)2 on sapphire substrate CMP was investigated. According to the results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), it was found there were solid-chemical reactions between Sr(OH)2 and sapphire and Al2Si2O7·2H2O, Al2SiO5, SrAl2Si2O8 and SrAl2O4 were generated on the sapphire surface, which improved chemical action effectively and material removal rate. This CMP method of improving chemical action has important significance to actual production.
MYB transcription factors are widespread in plants and play key roles in plant development. Although MYB transcription factors have been thoroughly characterized in many plants, genome-wide analysis of the MYB gene family has not yet been undertaken in Brachypodium distachyon. In this study, 122 BdMYB transcription factors were identified, comprising 85 MYB-R2R3, 34 MYB-related and three MYB-R1R2R3. Phylogenetic analysis showed that BdMYBs, OsMYBs and AtMYBs with similar functions were clustered in the same subgroup, and the phylogenetic relationships of BdMYB transcription factors were supported by highly conserved motifs and gene structures. Two cis-elements were found in the promoters of BdMYB genes. One is related to plant growth/development, the other is related to stress responses. Gene Ontology (GO) analysis indicated that most of the BdMYB genes are involved in various biological processes. The chromosome distribution pattern strongly indicated that genome-wide tandem and segment duplication mainly contributed to the expansion of the BdMYB gene family. Synteny analysis showed that 56, 58 and 61 BdMYB genes were orthologous to rice, maize and sorghum, respectively. We further demonstrated that BdMYB genes have evolved under strong purifying selection. The expression profiles indicated that most BdMYB genes might participate in floral development and respond to abiotic stresses. Additionally, 338 pairs of proteins were predicted to interact by constructing the interaction network. This work laid the foundation and provided clues for understanding the biological functions of these transcription factors.
SiO2 is a kind of widely used dielectric material in ULSI and its chemical mechanical planarization (CMP) is one of the most difficult processes. In this paper, the CMP mechanism and the effect of abrasive on SiO2 dielectric were analyzed; the different factors of affecting the CMP were analyzed. A kind of organic alkali was chosen to act as the pH regulator and complexation agent to enhance the chemical effect. The silica sol was selected as abrasive to realize no contamination, low viscidity, proper hardness and easy to clean. The effect of different concentration of abrasive on the removal rate and surface performance were studied. Further more the influence of polishing slurry flow and surfactant on removal rate were analyzed. The final planarization was realized.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)