Abstract:
An inspection device for examining a piece of aperture graphite of an extraction electrode, and the aperture graphite includes a to-be-examined curve and a to-be-examined engagement portion. The inspection device includes a sidewall surface having a standard curve marked thereon, and an examination engagement portion having a predetermined positional relationship with the sidewall surface. After the to-be-examined engagement portion is engaged with the examination engagement portion, and after the to-be-examined curve is projected onto the sidewall surface, the suitability of the aperture graphite can be determined according to the amount of differences between the projected to-be-examined curve and the standard curve.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an inspection device for an ion implanter, and in particular, to an inspection device for examining a piece of aperture graphite of an extraction electrode of an ion implanter. 
     BACKGROUND OF THE INVENTION 
     Recently, the ion implanting technology has been well developed. The recently available ion implanting technology not only satisfies needs for various semiconductor doping processes, but also becomes the most essential doping technology in the process for fabricating very large semiconductor integrated circuits. 
     An ion implanter is an apparatus for carrying out the ion implanting technology, including an ion source system for generating ions, a mass analyzer for separating major doped ions, and an accelerator for accelerating the ions to be implanted. The ion source system includes an evaporator, an arc chamber, a magnet, and an extraction electrode. The detailed description of the arc chamber and extraction electrode will be made in the following. 
     Referring to FIG. 1, plasma  3  is produced by the ion source (not shown) accommodated in an arc chamber  1  having an outlet  11 . An extraction electrode  2  includes a suppression electrode  21 , a ground electrode  22 , and an insulator  23 . The suppression electrode  21  includes two suppression electrode plates  211  and two suppression electrode aperture graphite elements  212 . The ground electrode  22  includes two ground electrode plates  221  and two ground electrode aperture graphite elements  222 . The suppression electrode  21  is provided with a suppression voltage SV, and the ground electrode  22  is grounded. 
     A suppression electrode aperture  213  is formed between the two suppression electrode plates  211  and between the two suppression electrode aperture graphite elements  212 . A ground electrode aperture  223  is formed between the two ground electrode plates  221  and between the two ground electrode aperture graphite elements  222 . 
     The ion beam from the arc chamber  1  is attracted out via the outlet  11  by the extraction electrode  2 . The ion beam attracted out passes through the suppression electrode aperture  213  and the ground electrode aperture  223  while being focused for the next treatment. 
     Referring to FIGS. 2 and 1, the extraction electrode  2  includes a suppression electrode  21  and a ground electrode  22 . The suppression electrode  21  includes two suppression electrode plates  211  and two suppression electrode aperture graphite elements  212 . The ground electrode  22  includes two ground electrode plates  221  (not shown) and two ground electrode aperture graphite elements  222  (not shown). The construction of the ground electrode  22  and that of the suppression electrode  21  are substantially similar to each other. 
     Referring to FIG. 3A, each of the suppression electrode aperture graphite elements  212  includes a first to-be-examined curve  2121 , two first engagement surfaces  2122 , two second engagement surfaces  2123 , and a first lower surface  2124 . Referring to FIG. 3B, each of the ground electrode aperture graphite elements  222  includes a second to-be-examined curve  2221 , two third engagement surfaces  2222 , and a second lower surface  2223 . 
     Referring again to FIG. 1, the extraction electrode  2  is used for attracting the ion beam from the arc chamber  1  in order to produce an ion beam current. Then, the ion beam current is focused. The suppression electrode aperture graphite elements  212  and the ground electrode aperture graphite elements  222  are those in contact with the ion beam current. 
     The curvatures of the arc surfaces of each of the suppression electrode aperture graphite elements  212  and each of the ground electrode aperture graphite elements  222  influence the diffraction of the ion beam current passing through the suppression electrode aperture  213  and the ground electrode aperture  223 , and also influence the focusing of the ion beam current. The degrees of the influences can be examined during the tuning process of the ion beam, with reference to the variation of the suppression voltage SV. 
     In the extraction electrode  2 , the suppression electrode aperture graphite elements  212  and the ground electrode aperture graphite elements  222  are considered as consumables. After they are utilized for some time, the first to-be-examined curve  2121  and the second to-be-examined curve  2221  are easily deformed and this can affect the ability of tuning ions of the ion implanter. In this case, the ion beam current does not reach a normal value, and the suppression voltage SV has to be increased in order to increase the focusing ability. According to this method, some electric power is wasted and other elements (not shown) within the extraction electrode  2  can be damaged in a short period of time. 
     In addition, if the deformation of the arc surface of the ground electrode aperture graphite element  222  and that of the suppression electrode aperture graphite element  212  have to be examined before each operating process, the steps of mounting a plurality of elements, vacuuming, tuning the ion beam, and the like are needed. Thus, a high manufacturing cost will be incurred. 
     SUMMARY OF THE INVENTION 
     In accordance with the first aspect of the invention, an inspection device for examining a piece of aperture graphite of an extraction electrode is disclosed. The aperture graphite has a to-be-examined curve and a to-be-examined engagement portion. The inspection device comprises a sidewall surface having a standard curve marked thereon, and an examination engagement portion having a predetermined positional relationship with the sidewall surface while the to-be-examined engagement portion is engaged with the examination engagement portion and the to-be-examined curve is projected onto the sidewall surface. The suitability of the aperture graphite can be determined according to the amount of difference between the projected to-be-examined curve and the standard curve. 
     The amount of difference between the projected to-be-examined curve and the standard curve comprises area difference that is the difference between the area enclosed by the projected to-be-examined curve and that by the standard curve, and maximum distance difference that is the maximum distance difference between the projected to-be-examined curve and the standard curve. 
     The aperture graphite is determined as unsuitable when the maximum distance difference is larger than 0.5 mm. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view showing an arc chamber and an extraction electrode. 
     FIG. 2 is a pictorial view of the extraction electrode. 
     FIGS. 3A and 3B are pictorial views of a suppression electrode aperture graphite element  212  and a ground electrode aperture graphite element  222 . 
     FIGS. 4A and 4B are pictorial views from two different standpoints of the inspection device in accordance with the invention. 
     FIG. 5A shows an example of using the inspection device to examine the suppression electrode aperture graphite element in accordance with a preferred embodiment of the invention. 
     FIG. 5B shows the result of examination as illustrated in FIG.  5 A. 
     FIG. 5C shows another example of using the inspection device of the invention to examine the suppression electrode aperture graphite element having wear. 
     FIG. 5D shows the result of examination as illustrated in FIG.  5 C. 
     FIG. 6A shows another example of using the inspection device of the invention to examine the suppression electrode aperture graphite element. 
     FIG. 6B shows the result of examination as illustrated in FIG.  6 A. 
     FIG. 6C shows another example of using the inspection device of the present invention to examine the suppression electrode aperture graphite element having wear. 
     FIG. 6D shows the result of examination as illustrated in FIG.  6 C. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 4A, an inspection device  4  is formed with a first reference surface  41 , a first sidewall surface  42  substantially perpendicular to and connected with the first reference surface  41 , two first engagement surfaces  43  connected with and perpendicular to the first sidewall surface  42  and in parallel to the first reference surface  41 , two second engagement surfaces  44  each connected with and substantially perpendicular to the first sidewall surface  42  and the adjacent first engagement surface  43 , and a first standard curve  45  marked on the first sidewall surface  42 . 
     Referring to FIG. 4B, the inspection device  4  is further formed with a second reference surface  46 , a second sidewall surface  47  substantially perpendicular to and connected with the second reference surface  46 , two third engagement surfaces  48  connected with the second reference surface  46  and substantially perpendicular to the second reference surface  46  and the second sidewall surface  47 , and a second standard curve  49  marked on the second sidewall surface  47 . 
     Referring to FIG. 5A, to examine a suppression electrode aperture graphite element  212 , let the graphite element  212  be engaged with the inspection device  4  along the direction of arrow A and let the first lower surface  2124  contact the first reference surface  41 , the first engagement surfaces  2122  contact the first engagement surfaces  43 , the second engagement surfaces  2123  contact the second engagement surfaces  44 , and the first to-be-examined curve  2121  contact the first sidewall surface  42 . The position of the suppression electrode aperture graphite element  212  for examination, viewed from the direction of the arrow A, is shown in FIG.  5 B. 
     Referring to FIG. 5B, the first to-be-examined curve  2121  of the suppression electrode aperture graphite element  212  is not damaged. Under this condition, the first lower surface  2124 , the second engagement surfaces  2123 , the first engagement surfaces  2122  are respectively in full contact with the first reference surface  41 , the second engagement surfaces  44 , and the first engagement surfaces  43 . The first to-be-examined curve  2121  and the standard curve  45  are superimposed. 
     Referring to FIG. 5C, the way to engage the suppression electrode aperture graphite element  212  with the inspection device  4  is similar to that as illustrated in FIG. 5A, and a detailed description is omitted. It should be noted that the first to-be-examined curve  2121  of the suppression electrode aperture graphite element  212  is damaged, and examination result is shown in FIG.  5 D. 
     Referring to FIG. 5D, under the condition that the first lower surface  2124 , the second engagement surfaces  2123 , the first engagement surfaces  2122  are respectively in full contact with the first reference surface  41 , the second engagement surfaces  44 , the first engagement surfaces  43 , there is an area difference DA 1  between the first to-be-examined curve  2121  and the first standard curve  45 , and the maximum distance difference is Dmax 1 . Based on the area difference DA 1  or the maximum distance difference Dmax 1 , the wear degree of the suppression electrode aperture graphite element  212  can be determined. If Dmax 1  is larger than, for example, 0.5 mm, it is determined that the suppression electrode aperture graphite element  212  cannot work normally any more. 
     Referring to FIG. 6A, to examine the ground electrode aperture graphite element  222 , let the graphite element  222  be engaged with the other part of the inspection device  4  along the direction of arrow B and let the second lower surface  2223  contact the second reference surface  46 , the third engagement surfaces  2222  contact the third engagement surfaces  48 , and the second to-be-examined curve  2221  contact the second sidewall surface  47 . The position of the ground electrode aperture graphite element  222  for examination, viewed along the direction of the arrow B, is shown in FIG.  6 B. 
     Referring to FIG. 6B, the second to-be-examined curve  2221  of the ground electrode aperture graphite element  222  is not damaged. Under this condition, the second lower surfaces  2223  and the third engagement surfaces  2222  are in full contact with the second reference surfaces  46  and the third engagement surfaces  48  respectively. The second to-be-examined curve  2221  is superimposed with the second standard curve  49 . 
     Referring to FIG. 6C, the way to engage the ground electrode aperture graphite element  222  with the inspection device  4  is similar to that as shown in FIG. 6A, and a detailed description is omitted. It should be noted that the second to-be-examined curve  2221  of the ground electrode aperture graphite element  222  is damaged, and the examination result is shown in FIG.  6 D. 
     Referring to FIG. 6D, under the condition that the second lower surface  2223  and the third engagement surfaces  2222  are in full contact with the second reference surface  46  and the third engagement surfaces  48  respectively, there is an area difference DA 2  between the second to-be-examined curve  2221  and the second standard curve  49 , and the maximum distance difference is Dmax 2 . Based on the area difference DA 2  or the maximum distance difference, the wear degree of the ground electrode aperture graphite element  222  can be determined. If Dmax 2  is larger than, for example, 0.5 mm, it is determined that the suppression electrode aperture graphite element  222  cannot work normally any more. 
     Thus, as a result of directly examining the to-be-examined curve of the aperture graphite, the time used for examining is saved, and complicated electrical property examination procedures can be avoided. 
     While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications. For example, in the above preferred embodiment, the inspection device  4  has the function of simultaneously examining the suppression electrode aperture graphite element  212  and the ground electrode aperture graphite element  222 . However, the device  4  can also be designed into two parts for examining these graphite elements  212  and  222  respectively. Furthermore, for the suppression electrode aperture graphite element  212 , the first engagement surfaces  2122 , the second engagement surfaces  2123 , and the first lower surface  2124  can be combined into a to-be-examined engagement portion. Similarly, for the ground electrode aperture graphite element  222 , the third engagement surfaces  2222 , and the second lower surface  2223  can be combined to form another to-be-examined engagement portion. 
     Moreover, for the inspection device  4 , the first reference surface  41 , the first sidewall surface  42 , the first engagement surfaces  43 , and the second engagement surfaces  44  can be combined to form an examination engagement portion. Similarly, the second reference surface  46 , the second sidewall surface  47 , and the third engagement surfaces  48  can also be combined to form an examination engagement portion. 
     Thus, for various types of aperture graphite and the inspection devices, as long as the to-be-examined engagement portion and the examination engagement portion can be engaged with each other, by marking the standard curve on the first sidewall surface  42  or the second sidewall surface  47 , examination can be carried out.