Electron microscopy
  
BPSG (Boron Phosphosilicate Glass)
- Integrated Circuits and Materials -
- An Online Book -
Integrated Circuits and Materials                                                                                  http://www.globalsino.com/ICsAndMaterials/        


Chapter/Index: Introduction | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Appendix

=================================================================================

Borophosphosilicate glass (BPSG) has been used for the premetal dielectric (PMD) or interlayer dielectric (ILD) to reduce the required reflow temperature. Figure 4575a shows the etch processes in a CMOS IC chip.

Figure 4674. Etch processes in a CMOS IC chip.

Figure 4575a. Etch processes in a CMOS IC chip. [1]

Table 4575. BPSG reactive ion etch (RIE).

Etch condition Line-edge roughness (LER) Reference

Ar:O2:C4F8 :CO in the ratio 20:1:1.2:20 at the chamber pressure of 75 mT with RF2 at 2000 W

 High (Figure 4575b (a)) [2]
Ar:O2:C4F8 :CO in the ratio 15:0.5:1.2:10 at the chamber pressure of 100 mT with RF2 at 600 W Low (Figure 4575b (c)) [2]

The high LER was mainly originated from two reasons:
          i) High flow rate of O2 and CO to generate the oxygen species, resulting in the removal of the fluorocarbon polymer deposited along the sidewalls leaving them unprotected against ion-bombardment during the RIE process.
          ii) High RF2 power that is essential to remove the fluorocarbon polymer based −CF2− repeating unit when using C4F8 based processes.

Figure 4674. Etch processes in a CMOS IC chip.

Figure 4575b. RIE profiles in BPSG: Low fluorocarbon polymer during the process resulted in (a) high LER and (b) low RIE lag. High fluorocarbon polymer present during the process protected the side-walls against ion-bombardment resulting in (c) low LER but (d) high RIE lag. The scale bars represent 120 nm. [2]

By doping SiO2 with boron and phosphorous, the film boron phosphorous silicate glass (BPSG) has good smoothing of step corners, and it can be made to reflow at high temperature (850–959 °C). [3] The formation of the doped BPSG using n-type lightly doped Si wafers has been widely studied. [4-8] In their studies, dielectric glass layers were deposited on the wafers with Si(OC2H5)4, B(OCH3)3 and PH3 gas sources and O2 and N2 carrier gases in (LP-CVD) reactors. These LPCVD glasses are amorphous, more fluid, have low connectivity and have a released structure. Since the reflow characteristics are mainly controlled by viscosity, which in turn is a function of glass chemical bonding [7,8] and structure [8], less viscous, non-crystallized glasses are ideally used for reflow and planarization.

 

 

============================================

         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         
         

 

 

 

 

 

 









































































[1] Hong Xiao, Introduction to semiconductor manufacturing technology, 2012.
[2] Parijat Bhatnagar, Siddhartha Panda, Nikki L. Edleman, Scott D. Allen, and Richard Wise, and Arpan Mahorowala, Controlling line-edge roughness and reactive ion etch lag in sub-150 nm features in borophosphosilicate glass, Journal of Applied Physics, 101, 076102 (2007).
[3] Parshuram B. Zantye, Ashok Kumar, A.K. Sikder, Chemical mechanical planarization for microelectronics applications, Materials Science and Engineering R 45 (2004) 89–220.
[4] K. Kobayashi, Low polarization and low temperature reflow of inorganic borophosphosilicate glasses formed from organic sources, Mater. Sci. Eng. 98 (2, 15) (2003) 181.
[5] K. Kobayashi, Relationship between electronic molar polarizability and super low dielectric constant in B2O3–BeF2–C glass systems, J. Phys. Chem. Solids 59 (9) (1998) 1671.
[6] K. Kobayashi, I. Mizushima, Reflow of BeF2, B2O3, GeO2, SiO2 glasses and application of their membranes to metal-oxide-silicon (MOS) capacitors, Mater. Sci. Eng. B 39 (1996) 224.
[7] K. Kobayashi, H. Sasaki, Viscous flow of ZnF2- and Si3N4-containing borosilicate glasses and their applications to MOS capacitors, Mater. Res. Bull. 33 (5) (1998) 811.
[8] K. Kobayashi, Improvement of polarizable capacitance—voltage curves of MOS capacitors passivated with BN-and PbF2-containing SiO2–B2O3–GeO2 glasses, J. Non-Cryst. Solids 217 (2–3) (1997) 323.

 

 

 

 
=================================================================================