Particle Metrology in CMP Slurries - Potential and Limitations of Relevant Measuring Methods
- PDF / 1,385,063 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 40 Downloads / 211 Views
0991-C04-02
Particle Metrology in CMP Slurries - Potential and Limitations of Relevant Measuring Methods Michael Stintz1, Herbert Barthel2, and Mansour Moinpour3 1 Inst. of Chemical Engineering, TU Dresden, Helmholtzstr. 10, Dresden, 01062, Germany 2 Wacker Chemie AG, München, 81737, Germany 3 Intel Corporation, Santa Clara, CA, 95052 ABSTRACT The design of nanostructured materials like CMP slurries on an industrial scale requires the control of disperse systems of nanoparticles as well as of single isolated "bad" particles . It is well known that slurry abnormalities resulting from large abrasive particles and abrasive particles agglomeration can cause defects on wafer surfaces during CMP. Particle-particle interactions generate secondary nanometer structures, clusters or agglomerates, which can dominate the relevant properties of the bulk material. Size and structure of these particle agglomerates/structures are the result of a dynamic equilibrium between agglomeration and desagglomeration. There is still a lack of understanding of these secondary soft nano- up to micro- particles because no adequate characterization methods are established. Dilution and other preparation treatment to enable analysis by laboratory methods like TEM or AFM will distort the interparticle forces and will generate artifacts. Hence characterization methods are under investigation which can tolerate a high number of particles in the sensing zone. These high concentration methods often deliver ambiguous results. Consequently different physical principles have to be combined to get unambiguous information on the disperse state. Performance characteristics of ultrasonic spectroscopy, photon correlation spectroscopy, analytical photo-centrifugation method combined with the high spatial resolution as well as special single particle optical counters are discussed on examples.
INTRODUCTION Even though CMP slurries are composed of very fine particles up to 200 nanometers, “coarse” particles of some micrometers are often present in slurries, probably as a result of agglomeration and contamination. These relatively large particles are assumed to cause microscratches during polishing and subsequent yield loss [1]. Improved control of the abrasive behavior in the CMP process demands a detailed understanding of the role played by relevant parameters, such as particle and wafer mechanical and surface properties [2, 3]. The evaluation and the optimization of these procedures require suitable methods for particle size analysis. An overview of methods for slurry characterization is given in reference [4]. Furthermore the dispersibility of agglomerates is evaluated considering drying agglomerates. The influence of coarse particles on the result of polishing and microscratches is investigated using filtered and unfiltered slurries as well as slurries containing drying agglomerates. For these experiments slurries based on silica particles (colloidal or pyrogenic silica) were used [5].
PARTICLE AND PARTICLE SYSTEMS CHARACTERIZATION METHODS
From < 0,1 Vo
Data Loading...
