Surface analytical techniques, semiconductor problems

However, this article is not intended to provide an exhaustive review of the voluminous literature on the application of surface analytical techniques to semiconductor problems. Numerous reviews have been published which have treated various aspects of these applications (1-jj). This article is intended to give an overview, drawing from more recent publications, of the ways in which surface analysis continues to play a vital role in the development and application of the numerous material technologies involved in semiconductor processes. In addition, the need for further development of surface techniques and a summary of the materials problem that do not lend themselves to the available analytical techniques are described. 

RBS has been in use since the 1960s for bulk materials analysis, and increasingly since the 1970s for thin-film analysis, particularly in the semiconductor field. The overall number and range of applications are enormous, but those dealing specifically with surface problems are less numerous. Nevertheless RBS ranks along with SSIMS and ISS as one of the major surface analytical techniques. 

It would be impossible to cover in a limited space all the situations in semiconductor technology in which surface analytical techniques have been applied, so instead the following four typical problem areas have been selected to demonstrate the application. They are typical in that the nature of the information sought in each ca.se is similar to that sought in many other problem areas in the field. 

Despite these problems. WG2 currently has two items under development. Procedure for Certification of lon-lmplanted Reference Materials for Analysis of Semiconductor Wafers and Ion-Implanted Dosimetry Calibration by Surface Analytical Techniques. 

A wide array of analytical techniques is employed in conjunction with MS and the best tool—or a combination—is ultimately selected depending on the problem at hand. In a survey of 22,155 analyses spanning 7 years (from 2000 to 2006) from a laboratory of Samsung in Korea [11], MS was included in the categories chemical analyses and surface analyses (see Table 40.2). From the secondary ion mass spectrometry (SIMS) analyses, 60% was semiconductor work, subdividing into the analysis issues as detailed in Table 40.3. 

Before describing the surface analysis of the materials listed above, the advantages and limitations of the surface-specific techniques to be used should be discussed. The basic principles, instrumentation and main applications of photoemission (1-3] and Auger [4,51. spectroscopies, as well as of SAM [6.7] and ELS [8-11] have already been described in several reviews, while Seah and Briggs [12] have surveyed in detail the principal features of many suri ace-specific techniques. Of major interest here are those characteristics of each technique that, on the one hand, may be employed strategically to solve a given analytical problem, but that on the other may affect the reliability of the results. In Table 1 the relative merits of the techniques are rated with respect to those properties likely to be important in the surface analy.sis of semiconductors and microelectronic devices. 

In eadi specific case the choice of an adsorbent, electrophysical parameters and the method of registration of its change as well as the choice of various pre-adsorption treatment techniques of the surface of adsorbent is dictated by the type and nature of analytical problem to be solved. For instance, if particles active from the standpoint of the change in electrophysical parameters of semiconductor adsorbent occur on the surface of the latter due to development of a chemical reaction involving active particles, it is natural to use either semiconductor material catalyzing the reaction in question or if this is not possible specific surface dopes accelerating the reaction. Above substances are used as operational element of the sensor. If such particles occur as a result of adsorption from adjacent volume, one can use semiconductor materials with maximum adsorption sensitivity to the chosen electrophysical parameter with respect to a specific gas as operational element. 

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