The Effect of Microstructure on Chemical Mechanical Polishing Process of Thin-Film Metals

2007 ◽  
Author(s):  
Joseph Bonivel ◽  
Sarah Biltz ◽  
Elon Terrell ◽  
Burak Ozdoganlar ◽  
C. Fred Higgs
Keyword(s):  
Thin Film ◽  
Integrated Circuits ◽  
Data Storage ◽  
Chemical Mechanical Polishing ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Metal Thin Films ◽  
Storage Devices ◽  
Multi Scale ◽  
Chemical Mechanical Polishing Process

Chemical mechanical polishing (CMP) is a critical nanomanufacturing process used to remove or planarize ultrathin metallic, dielectric, or barrier layers on silicon wafers. The CMP process is a vital interim fabrication step for integrated circuits and data storage devices. One of the major shortcomings of existing CMP models is that they do not account for crystallographic effects of the thin film metal materials when predicting material removal rates. This work investigates the effect of the microstructure on the CMP of copper and metal thin films on silicon wafer. Nanoindentation tests were conducted to measure the hardness variations across a wafer surface due to the crystallography of the metal films. Spatial variation of mechanical properties was also input into an existing multi-scale CMP model. Nano-characterization and CMP experimental results are presented and compared to an existing CMP wear model.

Dynamics of the Formation of the Subambient Pressure Distribution During Chemical-Mechanical Polishing

2007 ◽  
Author(s):  
A. Osorno ◽  
S. Tereshko ◽  
I. Yoon ◽  
S. Danyluk
Keyword(s):  
Integrated Circuits ◽  
Pressure Distribution ◽  
Chemical Mechanical Polishing ◽  
Rotational Speed ◽  
Silicon Wafers ◽  
Mechanical Polishing ◽  
Wafer Surface ◽  
Abrasive Particles ◽  
Pressure Distributions ◽  
Time Period

Chemical-Mechanical Polishing is used to polish silicon wafers in the manufacturing of integrated circuits. Wafers are pressed, electronics side down, onto a rotating pad that is flooded with a slurry containing abrasive particles. The slurry is entrained in the interface and the abrasive particles slide against the silicon and polish it. Our previous work has shown that subambient pressures develop at the silicon/pad interface and we have measured this pressure and its distribution over the wafer surface (1). However, our experiments have been limited to those conditions where the pad rotates and the wafer slides on the pad but the wafer itself does not rotate. Our experiments showed a skewed pressure distribution. This paper describes experiments and pressure distribution measurements where the wafer, as well as the pad/platen is rotated (2). Specifically-designed wireless electronic transmitters and receivers were built and used to measure the interfacial pressures at the silicon/pad interface. Subambient stress maps and temperatures have been measured and Figure 1 shows an example of a skewed pressure distribution when the silicon is not rotated and Figure 2 shows the pressure distribution for the same wafer while it is rotating. The subambient pressures develop over a 2 second time period from when the rotation started. The pressure distributions are symmetric in spite of the lean and tilt of the wafers. The rotational speed and other variables have a big influence on the polishing rate and this will be discussed in the talk.

Surface-particle interactions in the chemical mechanical polishing process

1997 ◽  
Vol 501 ◽  
Author(s):  
J. J. Adler ◽  
Y. I. Rabinovich ◽  
R. K. Singh ◽  
B. M. Moudgil
Keyword(s):  
Integrated Circuits ◽  
Chemical Mechanical Polishing ◽  
Difficult Problem ◽  
Mechanical Polishing ◽  
Particle Interactions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Chemical Mechanical Polishing Process ◽  
Surface Particle ◽  
The Stability

ABSTRACTChemical mechanical polishing (CMP) is a critical step in the fabrication of integrated circuits. Each layer of deposited material must be planarized before the next layer of circuitry can be formed. In CMP, a chemically active solution is used to modify the substrate so that a particulate abrasive may polish more efficiently. Modification of the surface often requires high oxidizer concentrations or pH extremes. Under these circumstances the stability of the polishing slurry and prevention of particulate attachment to the substrate is a difficult problem. In this study, atomic force microscopy (AFM) has been used to directly measure the forces between surfaces that simulate those in CMP. Initial investigation has focused on modeling the polishing of tungsten interconnect material by alumina slurries at acidic pH and evaluating the role surfactants can play in the stabilization of the polishing slurry and CMP processes.

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