Cadmium Telluride (CdTe), one of II-VI group compound semiconductors, was used as a material of X-Ray detector, since it has good features of high absorption rate and high conversion efficiency of X-Ray, resulting from its excellent electric properties. However, a rough surface of the CdTe thin-film...
Cadmium Telluride (CdTe), one of II-VI group compound semiconductors, was used as a material of X-Ray detector, since it has good features of high absorption rate and high conversion efficiency of X-Ray, resulting from its excellent electric properties. However, a rough surface of the CdTe thin-film causes a delay of electric speed and current concentration to the uneven part of the surface, resulting in making electric uniformity worse. Therefore, it is necessary to improve the surface roughness of the CdTe X-Ray detector which is possible to achieve a higher electric uniformity, a shorter signal delay, and more clear images.
Although there are a lot of planarization methods, among them, Chemical Mechanical Planarization (CMP) using for CMP is possible to apply to global planarization. Therefore this paper deals with CMP process as a method to improve the surface roughness and Material Removal Rate (MRR) of the CdTe substrate. In CMP process, there are many factors affecting the removal rate. This paper mainly focuses on the chemical effect of slurry. Key factor in chemical reaction are concentration of oxidizer and process temperature. This study revealed that it was essential to choose a proper oxidizer and slurry temperature to improve the removal rate and the surface roughness in CdTe CMP process.
In order to study effects of chemical reaction, X-Ray Photoelectron Spectroscopy (XPS) was performed on CdTe sample after dipping depending on type of oxidizer. The result of XPS shows that TeO2 have formed by oxidizing agent. Also, the results of CdTe CMP showed that removal rate and surface roughness improved in proportion to concentration of oxidizer and slurry temperature. But when added over proper oxidizer, MRR did not increased, the scratches were created and surface got more worse. The same result also appeared when increased temperature of slurry. There seems to be lots of reasons for this result, such as change of pH, surface protection of oxide film, excessive chemistry and etc. Also, the result of leak current measurement of improved surface as CMP process, it could be confirmed that leak current is reduced.
This paper focuses on chemical reaction on the surface of CdTe. However, there are lots of methods to improve polishing in CMP process besides mechanical elements. Therefore we will need to study mechanical effect like abrasive size, abrasive concentration, down pressure.
Cadmium Telluride (CdTe), one of II-VI group compound semiconductors, was used as a material of X-Ray detector, since it has good features of high absorption rate and high conversion efficiency of X-Ray, resulting from its excellent electric properties. However, a rough surface of the CdTe thin-film causes a delay of electric speed and current concentration to the uneven part of the surface, resulting in making electric uniformity worse. Therefore, it is necessary to improve the surface roughness of the CdTe X-Ray detector which is possible to achieve a higher electric uniformity, a shorter signal delay, and more clear images.
Although there are a lot of planarization methods, among them, Chemical Mechanical Planarization (CMP) using for CMP is possible to apply to global planarization. Therefore this paper deals with CMP process as a method to improve the surface roughness and Material Removal Rate (MRR) of the CdTe substrate. In CMP process, there are many factors affecting the removal rate. This paper mainly focuses on the chemical effect of slurry. Key factor in chemical reaction are concentration of oxidizer and process temperature. This study revealed that it was essential to choose a proper oxidizer and slurry temperature to improve the removal rate and the surface roughness in CdTe CMP process.
In order to study effects of chemical reaction, X-Ray Photoelectron Spectroscopy (XPS) was performed on CdTe sample after dipping depending on type of oxidizer. The result of XPS shows that TeO2 have formed by oxidizing agent. Also, the results of CdTe CMP showed that removal rate and surface roughness improved in proportion to concentration of oxidizer and slurry temperature. But when added over proper oxidizer, MRR did not increased, the scratches were created and surface got more worse. The same result also appeared when increased temperature of slurry. There seems to be lots of reasons for this result, such as change of pH, surface protection of oxide film, excessive chemistry and etc. Also, the result of leak current measurement of improved surface as CMP process, it could be confirmed that leak current is reduced.
This paper focuses on chemical reaction on the surface of CdTe. However, there are lots of methods to improve polishing in CMP process besides mechanical elements. Therefore we will need to study mechanical effect like abrasive size, abrasive concentration, down pressure.
Keyword
#CdTe CMP
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