Abstract:
The present invention involves an ion beam angular measurement apparatus for providing feedback for a predetermined set ion beam angle comprising an arrangement of composite pillars formed on an insulating material and wherein the composite pillars selectively allow ion beams to penetrate a first layer of a pillar, wherein resistivity measurements are taken for each of the composite pillars before and after test ion beam implantation and wherein the resistivity measurements yield information relating to an angle of the ion beam during test.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates generally to ion implantation, and, more particularly, to a systems and methods for measuring beam angle in an ion implanter. 
       BACKGROUND OF THE INVENTION 
       [0002]    Ion implantation is a physical process, as opposed to diffusion, which is a chemical process that is employed in semiconductor apparatus fabrication to selectively implant dopant into semiconductor workpieces and/or wafer material. Thus, the act of implanting does not rely on a chemical interaction between a dopant and the semiconductor material. For ion implantation, dopant atoms/molecules are ionized and isolated, sometimes accelerated or decelerated, formed into a beam, and swept across a workpiece or wafer. The dopant ions physically bombard the workpiece, enter the surface and come to rest below the surface and typically come to rest below the workpiece surface in the crystalline lattice structure thereof. 
         [0003]    An ion implantation system is a collection of sophisticated subsystems, each performing a specific action on the dopant ions. Dopant elements, in gas or solid form, are positioned inside an ionization chamber and ionized by a suitable ionization process. In one exemplary process, the chamber is maintained at a low pressure (vacuum). A filament is located within the chamber and is heated to the point where electrons are created from the filament source, for example. The negatively charged electrons are attracted to an oppositely charged anode also within the chamber. During the travel from the filament to the anode, the electrons collide with the dopant source elements (e.g., molecules or atoms) and create a host of positively charged ions. 
         [0004]    Generally, other positive ions are created in addition to the desired dopant ions. The desired dopant ions are selected from the ions by a process referred to as analyzing, mass analyzing, selection, or ion separation. Selection is accomplished utilizing a mass analyzer that creates a magnetic field through which ions from the ionization chamber travel. The ions leave the ionization chamber at relatively high speeds and are bent into an arc by the magnetic field. The radius of the arc is dictated by the mass and velocity of individual ions, and the strength of the magnetic field. An exit slit of the analyzer permits only one species of ions, the desired dopant ions, to exit the mass analyzer. 
         [0005]    Continuing on, the dopant ions are directed towards a target wafer at an end station. The dopant ions, as a beam, impact the wafer with a specific beam current. In order to obtain substantially uniform apparatus characteristics, the beam is required to be substantially uniform and an angle of incidence of the beam is also required to be substantially uniform. It is advantageous to control and/or measure the beam incidence angle accurately, since the electrical characteristics of advanced apparatus are dependent on the beam incidence angle. It is often advantageous to supply beams at incidence angles other than perpendicular to the substrate plane for reasons associated with the geometry or function of the semiconductor apparatus being manufactured. 
         [0006]    As apparatus sizes are further reduced, manufacturers require better accuracy in measurements of beam incidence angles in the ion implantation process. Prior art ion beam angular measurement techniques utilize actual angle measurement at the wafer chuck or support hardware. Advanced apparatus require ever increasing precision in the measurement of the angle of the incoming ion beam. Ion beam angle at low energies is difficult to measure using conventional metrology. Typical apparatus utilize a multitude of masks and operations to make a transistor that is sensitive to ion implantation angle. 
         [0007]    The angular measurement is typically not made in real time but is done periodically. Angular measurement is typically performed utilizing mechanical tools, laser beams, current measurements, power measurements, etc. However, these techniques have various limitations in terms of accuracy. 
         [0008]    For higher energy implantation (e.g., greater that 50 keV) angle can be measured fairly well utilizing the ion channeling effect to measure angle. The lower the energy is below 50 keV the less effective is the resultant angular measurement. However, there is an interest in measuring ion angles for ion beams having energies below 5 keV because it is of practical importance in building advanced semiconductor apparatus and it is the energy range that is typically the most difficult for a commercial ion implanter to control in terms of ion beam angle, for example. 
         [0009]    If the ion channeling techniques do not work because of the energy levels involved, manufacturers are forced to build some type of structure that is no longer a bare wafer. That structure has basically been a transistor, such as an NMOS transistor and one or two levels of metal in order to measure beam angle. That involves at least 5 or 6 masks and at least dozen processing steps. Once the structure has been built and implanted it is tested electrically using probes, for example. 
         [0010]    Accordingly, suitable apparatus and methods for accurately measuring beam angles in an ion implanter at low energies, at lower cost, etc. are desirable, wherein the apparatus utilize fewer masks and operations to fabricate. 
       SUMMARY OF THE INVENTION 
       [0011]    The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the invention. This summary is not an extensive overview of the invention, and is neither intended to identify key or critical elements of the invention, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later. 
         [0012]    The present invention facilitates semiconductor apparatus fabrication by measuring ion beam angles utilizing high aspect ratio pillars of silicon on an insulating layer, for example. Two or more pillars are employed within an ion implantation system (e.g., using a single mask process and/or a two mask based system). The pillars(s) are operative to provide resistivity measurements before and after ion implantation (e.g., calibration), during ion implantation (e.g., in situ), and/or after ion implantation (e.g., verification). Based on the resistivity measurements, generation of an ion beam can be adjusted to improve uniformity of the beam angle as indicated. As a result, ion implantation can be performed with an improved angular uniformity and under tighter process controls. 
         [0013]    According to one aspect of the invention, an ion beam angular measurement apparatus for providing feedback for a predetermined set ion beam angle comprising an arrangement of composite pillars formed on an insulating material, wherein the composite pillars selectively allow ion beams to penetrate a first layer of a pillar, wherein resistivity measurements are taken for each of the composite pillars before and after test ion beam implantation, and wherein the resistivity measurements yield information relating to an angle of the ion beam during test. 
         [0014]    In another implementation of the invention, a method of fabricating a test ion beam angular measurement apparatus comprising forming composite pillars on a insulating layer, directing angular test ion beams at a pre-determined set ion beam angle toward the ion angular measurement apparatus located in an ion implantation system, measuring resistivity of the composite pillars before and after test ion beam implantation, as an indication of actual ion beam angle. 
         [0015]    Yet another aspect of the invention provides a method for fabricating an ion beam angular measurement mask apparatus for providing feedback for a predetermined set ion beam angle comprising an arrangement of slots formed on an insulating mask, wherein the slots selectively allow ion beams to penetrate a workpiece, wherein resistivity measurements are taken on the workpiece before and after test ion beam implantation, and wherein the resistivity measurements yield information relating to an angle of the ion beam during test. 
         [0016]    According to another aspect of the invention, a method of fabricating a test ion beam angular measurement apparatus comprising forming a structure associated with a workpiece, creating a first contact, a second contact and a third contact, measuring the resistivity between the first contact and the second contact, measuring the resistivity between the second contact and the third contact, measuring the resistivity between the first contact and the third contact; and developing calibration curves for an ion implanter under test based upon the various measurements. 
         [0017]    Yet another aspect of the invention provides a method of fabricating an ion beam angular measurement apparatus comprising forming composite pillars on a silicon layer workpiece, wherein the composite pillars comprise a silicon oxide with a layer of photoresist is formed on an n-type oxide layer, directing ion beams towards the ion beam angular measurement apparatus located within an ion implantation system, and measuring resistivity of the silicon layer workpiece as an indication of actual ion beam angle. 
         [0018]    To the accomplishment of the foregoing and related ends, the invention comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative aspects and implementations of the invention. These are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIGS. 1-8  are cross sectional views illustrating an ion implantation angular measurement apparatus that utilizes a single mask process in accordance with an aspect of the present invention; 
           [0020]      FIG. 9  is a top view illustrating an angular measurement apparatus utilizing a single mask in accordance with an aspect of the present invention; 
           [0021]      FIGS. 10-20  are cross sectional views illustrating an ion implantation angular measurement apparatus that utilizes a two mask process in accordance with at least one aspect of the present invention; 
           [0022]      FIG. 21  is a top view illustrating a two mask ion implantation angular measurement system in accordance with an aspect of the present invention; 
           [0023]      FIG. 22  is a top view illustrating an ion implantation angular measurement system that utilizes a slotted mask in accordance with an aspect of the present invention; 
           [0024]      FIG. 23  is a side view of a slotted mask ion implantation angular measurement apparatus in accordance with an aspect of the present invention; 
           [0025]      FIGS. 24 and 25  are side views of yet another ion implantation angular measurement apparatus in accordance with yet another aspect of the present invention; 
           [0026]      FIGS. 26 and 27  are side views of yet another ion implantation angular measurement apparatus in accordance with yet another aspect of the present invention; 
           [0027]      FIG. 28  is a top view of a serpentine ion implantation angular measurement apparatus in accordance with yet another aspect of the present invention; 
           [0028]      FIG. 29  is a side view of a serpentine ion implantation angular measurement apparatus in accordance with another aspect of the present invention; 
           [0029]      FIG. 30  is a flow diagram illustrating a method of fabricating an ion implantation angular measurement apparatus utilizing a single mask procedure in accordance with an aspect of the present invention; 
           [0030]      FIG. 31  is a flow diagram illustrating a method of fabricating an ion implantation angular measurement apparatus utilizing a two mask procedure in accordance with an aspect of the present invention; and 
           [0031]      FIG. 32  is a flow diagram illustrating a method of fabricating an ion implantation angular measurement apparatus in accordance with an aspect of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    The present invention will now be described with reference to the attached drawings, wherein like reference numerals are used to refer to like elements throughout. It will be appreciated by those skilled in the art that the invention is not limited to the exemplary implementations and aspects illustrated and described hereinafter. For the sake of providing a clear description of the invention, the structures and the methods will be described in connection with periodic pillar structures. However, it is to be expressly understood that this description is not intended to be self-limiting in any manner. It is contemplated that the concepts of the present invention may be utilized with other types and configurations of periodic structures (e.g., trenches and the like) without departing from the spirit and the scope of the invention 
         [0033]    The present invention facilitates semiconductor apparatus fabrication by measuring ion beam angles utilizing high aspect ratio pillars of silicon on an insulating layer, for example. Two or more pillars are employed within an ion implantation apparatus (e.g., using a single mask process and/or a two mask based system). The pillars(s) are operative to provide resistivity measurements before and after ion implantation (e.g., calibration), during ion implantation (e.g., in situ), and/or after ion implantation (e.g., verification). Based on the comparison of pillar resistivity measurements (i.e., before and after an ion implantation), generation of an ion beam can be adjusted to improve uniformity of the beam angle as indicated. As a result, ion implantation can be performed with an improved angular uniformity and under tighter process controls. 
         [0034]    The apparatus depicted in  FIGS. 1-9  are provided for illustrative purposes and are not intended to include all aspects, components, and features of an apparatus. Instead, the apparatus in  FIGS. 1-9  are depicted so as to facilitate a further understanding of the present invention using a single mask process. The apparatus in  FIGS. 1-9  can also be built up on a “ready made” silicon-on-insulator workpiece, polysilicon on thermal oxide, and the like, for example. 
         [0035]    Beginning with  FIG. 1 , a cross sectional view of a simplified exemplary portion of an ion implantation angular measurement apparatus  100  in accordance with an aspect of the present invention is illustrated. The angular measurement apparatus  100  can include a handle substrate  101  and an insulating support layer  102  (e.g., silicon dioxide, a fraction of a micron thick, e.g., 0.1-0.2 microns thick) formed upon the handle substrate  101  (e.g., approximately 770 microns thick), as illustrated, for example. 
         [0036]    An exemplary partial ion implantation angular measurement apparatus  200  illustrated in  FIG. 2  shows a single crystal silicon layer  104  formed, on an insulating layer  102 , for example. Together a handle substrate  101 , the insulating layer  102  and the silicon layer  104  can be referred to as a workpiece  108 . An ion implantation  106  is illustrated in  FIG. 2 , utilizing an ion beam, having a number of characteristics including, dopant type, dose, beam current, angle of incidence, energy, and the like. Although the ion implantation  106  is depicted as being substantially orthogonal to a surface of the silicon layer  104 , the implantation  106  can be at other incident angles with respect to the surface of the silicon layer  104 . Ion implantation is well known by those of skill in the art. 
         [0037]    A platen or electrostatic chuck (not shown) holds a handle substrate  101  and the platen is operable to move a workpiece  108  through an ion beam at a controlled rate, for example, so as to achieve desired implantation results. Generally, a given ion implantation  106  is performed in multiple passes of the workpiece  108  through the ion beam. By so doing, the substantially uniform implantation  106  across the workpiece  108  can be obtained because all parts or portions of the workpiece  108  move through the ion beam at about the same rate. An anneal  107  can be performed after the implantation  106  to repair any damage caused by the implantation  106 , for example. Annealing processes are well known by those of skill in the art. In  FIG. 3 , an oxide layer  110  can be formed on top of a single crystal silicon layer  104  employing thermal oxidation or deposition, for example. The formation of the oxide layer  110  is well known by those of skill in the art. 
         [0038]    Turning now to  FIG. 4  in yet another embodiment of the present invention, a photoresist  112  can be deposited on an oxide layer  110  using a single mask process, for example, on a partial ion implantation angle measurement apparatus  400 . The photoresist  112  can then be exposed  114  and etched  116 , as illustrated, for example. The process of photolithography in semiconductor apparatus manufacturing is well known by those of skill in the art.  FIG. 5  illustrates yet another embodiment of a partial ion implantation angle measurement apparatus  500  where a pillar first layer  118  of pillars  120  (e.g., pillars numbered  1 - 6 ) can be made out of a single crystal silicon layer  104  ( FIG. 4 ), for example. A pillar second layer  119  can be formed out of the oxide layer  110  in  FIG. 5  wherein a remaining photoresist  112  can be cleaned off or stripped  122  or left on using any photolithographic process that is well known to those of skill in the art. It is to be appreciated that any number of pillars, two or greater can be utilized in forming an angular measurement apparatus, of various widths, spacings, heights, materials, angular orientation on the workpiece, etc., and all are contemplated within this invention. 
         [0039]    After the photoresist  112  is stripped  122  in  FIG. 5  an optional standard clean  124  can be performed in  FIG. 6 . An implant test  126  can be performed at an angle θ  127  as illustrated in the cross sectional view of  FIG. 7 , for a given apparatus  700  that is being tested for a given ion implantation system and the apparatus  700  as illustrated is also shown in a top view in  FIG. 9 , for example. In the present example, six of the pillars  120  are shown (e.g., numbers  1 - 6 ) with an angular ion beam  126 , as illustrated. In this example the angular beam is shown directed at a clockwise angle θ  127  (e.g., from vertical). Under these conditions, pillar  6  (e.g., the right most pillar) will be the pillar with the greatest number of ions or dopant implanted  126  in a pillar first layer  118  (e.g., silicon), for example, whereas pillars  1 - 5  will be shielded from a portion of the ion implantation  126  by the pillar to their immediate right. In other words, pillar  5  is partially shielded by pillar  6 ; pillar  4  is partially shielded by pillar  5 ; and so on. Ions implanted into the second pillar layer  119  or the silicon dioxide insulating layer  102  does not change the resistivity of the pillars. Because the spacing is the same between the pillars in this example, after implantation  126  the resistivity of pillars  2  and  5  remains approximately equal, and the resistivity between  3  and  4  remains about equal, whereas the resistivity of pillars  1  and  6  is no longer equal and represents a function of the ion implantation angle θ  127 . It should be noted however that because of scattering effects that are well known by those of skill in the art, there may be different readings at the center of the pillars, as opposed to pillars at the edges. This is true even after accounting for differences in the line lengths of the pillars. If the ion implantation was coming down from the top of the ion implanter in a vertical fashion there would be no difference in resistivity between the pairs of the pillars, for example. It should be appreciated that the number of pillars can be two or greater, the spacing between pillars can be non-equal and the lengths of pillars can be non-symmetrical, the pillar materials can vary from one pillar to another, and the like, and all such variations are contemplated herein. In addition, these pillars can be part of a test apparatus or part of an apparatus wafer, for example. In  FIG. 8 , for example, an anneal  128  can be performed to repair any damage caused by the implantation  128  ( FIG. 7 ). 
         [0040]    Referring to  FIG. 9  is a top view of the angular measurement apparatus  900  shown for example in  FIGS. 6 ,  7  and  8 . Contact pads  130  (e.g., 100 microns×100 microns) are illustrated and numbered  1 A- 6 A and  1 B- 6 B, for example. Prior to the ion implantation  126  ( FIG. 7 ) the initial resistivity of pillar  1  and pillar  6  are approximately equal, the resistivity of pillar  2  and pillar  5  are approximately equal, and the resistivity of pillar  3  and pillar  4  are approximately equal. Pillars  3  and  4  have the largest resistivity initially because they have the longest lengths, whereas the resistivities of pillars  1  and  6  have the least resistivity initially due to having the shortest length. 
         [0041]    Once the test implantation  126  ( FIG. 7 ) and the optional anneal  128  ( FIG. 8 ) are performed the resistivity of the various pillars can be measured and compared as a function of the angle of implantation. The resistivity measurements can be carried out using probe instruments and electrical test equipment that are well known by those of skill in the art. The resistivity measurements can be made one pillar at a time connecting to a single set of contacts, or with twelve pins that make contact with all of the contact pins at the same time in order to make six resistivity measurements simultaneously, manually or automatically, etc. Initially, prior to implantation, the resistivity of each pillar is given by equation: 
         [0000]        R =rho× L /( A )   (Eq. 1) 
         [0042]    wherein rho is the variable resistivity of the doped pillars (e.g., 0.03 ohm-cm), L is the length (e.g., 50 micro-meters) and A is the cross section area (150 nanometers×100 nanometers). Therefore, for example, the resistivity of pillar  1  and pillar  6  are initially equal and R 1  and R 6  are equal to 1 million ohms, for example, the resistivity of pillar  2  and pillar  5  are initially equal and R 2  and R 5  are about 5 million ohms, and pillar  3  and pillar  4  are initially equal and R 3  and R 4  are approximately 9 million ohms. 
         [0043]    Approximately identical single mask angular measurement apparatus (e.g., apparatus ( 1 ), apparatus ( 2 ), apparatus ( 3 ), etc., like the apparatus illustrated in  FIG. 7  would be placed successively into an ion implanter at “known” angles (e.g., −2, −1, 0, 1, 2 degrees) and the resistivity of the pillars in those apparatus would be measured to develop calibration curves for the ion implanter being tested, for example. It is also possible to measure the angles as a function of pillar resistivity using mathematical modeling as contemplated in this invention. 
         [0044]    Referring now to  FIGS. 10-21 , they represent at least one embodiment of the present invention illustrated as a two mask implantation angular measurement apparatus. The advantage of the angular measurement apparatus formed with two masks with added complexity to the previous method is that it allows the top and bottom probe pads and leads to be doped more heavily than the pillars within the middle section of the apparatus which remains lightly doped. This may be necessary for testing low and mid-dose implantations, where the pads must be heavily doped to make a low contact resistance, but the pillars can be lightly doped to adequately detect the implantation angle under test. This will be discussed in detail the following discussion. 
         [0045]      FIG. 10  illustrates a cross sectional view of a simplified exemplary portion of an ion implantation angular measurement apparatus  100  in accordance with an aspect of the present invention. The angular measurement apparatus  1000  can include a handle substrate (not shown for simplification) and an insulating layer  1002  (e.g., silicon dioxide) formed upon the handle substrate, for example. The apparatus depicted in  FIGS. 10-21  are provided for illustrative purposes and are not intended to include all aspects, components, and features of the apparatus. Instead, the apparatus in  FIGS. 10-21  is depicted so as to facilitate a further understanding of the present invention using a dual or two mask process. The apparatus in  FIG. 10-21  can also be built up on a “ready made” silicon-on-insulator workpiece, for example. 
         [0046]    An exemplary partial ion implantation angular measurement apparatus  1100  illustrated in  FIG. 11  shows a silicon layer  1004  formed, on an insulating layer  1002 . It is to be appreciated that the silicon layer  1004  formed on the insulating  1002  can be replaced by a polysilicon layer deposited on the insulating layer  1002 , for example. Together a handle substrate, the insulating layer  1002  and the silicon layer  1004  can be referred to as a workpiece  1008 . An ion implantation  1006  is illustrated in  FIG. 11 , utilizing an ion beam, for example, a ribbon beam, having a number of characteristics including, dopant type, dose, beam current, angle of incidence, energy, and the like. Although the ion implantation  1006  is depicted as being substantially orthogonal to a surface of the silicon layer  1004 , the implantation  1006  can be at other incident angles with the surface of the silicon layer  1004 . Ion implantation is well known by those of skill in the art. 
         [0047]    A platen or electrostatic chuck (not shown) holds the handle substrate and the platen is operable to move the workpiece  1008  through the ion beam  1006  at a controlled rate, for example, so as to achieve desired implantation results. Generally, a given ion implantation  1006  is performed in multiple passes of the workpiece  1008  through the ion beam. By so doing, a substantially uniform implantation  1006  across the workpiece  1008  can be obtained because all parts or portions of the workpiece  1008  move through the ion beam at about the same rate. In contrast, other ion implantation systems employ a process disk that may also incorporate the present invention. An anneal  1007  can be performed after the implantation  1006  to repair damage caused by the implantation  1006 , for example. In  FIG. 12 , an oxide layer  1010  can be formed on top of the single crystal silicon layer  1004  employing thermal oxidation or deposition, for example. The formation of oxide layers utilizing various techniques is well known by those of skill in the art. 
         [0048]    Turning now to  FIG. 13  in yet another embodiment of the present invention, a first photoresist  1012  can be deposited on an oxide layer  1010  using a masking process, for example, on a partial ion implantation angle measurement apparatus  1300 . The first photoresist layer  1012  can then be exposed  1014  and patterned/etched  1016 . The process of photolithography in semiconductor apparatus manufacturing is well known by those of skill in the art.  FIG. 14  illustrates a partial measurement apparatus  1400  with a portion of the first photoresist layer  1012  and a portion of the oxide layer  1010  removed  1015 . The embodiment in  FIG. 15  illustrates a partial ion implantation angle measurement apparatus  1500  wherein the remaining first photoresist layer is stripped  1017 . A high dose implantation  1019  can be performed in  FIG. 16 , for example. The high dose implant  1019  is performed within regions  1020  of  FIG. 21  (i.e., a first region) and  1023  of  FIG. 21  (i.e., a second region). Contact pads  1021  (e.g., pads numbered  1 C- 6 C and  1 D- 6 D) and leads within region  1020  and  1023  must be heavily doped to make low resistance contacts pads  1021 . Area  1018 , i.e., 3 rd  region ( FIG. 21 ) is covered with a mask during the ion implantation  1019  ( FIG. 16 ) to prevent doping during the high dose implant  1019 . In  FIG. 17  as illustrated, a second photoresist  1020  can be deposited, patterned and etched  1021  on an oxide layer  1010 . As illustrated in  FIG. 18  pillars  7 - 12  are now formed on the on the insulating layer  1002  comprising, a first pillar layer  1018  made of silicon and a second pillar layer  1010  made of oxide, for example. A second photoresist layer  1020  can be removed or stripped  1025  after the etching of the oxide and silicon  1023  down to the insulating layer  1002 . As illustrated in  FIG. 19  an implant test  1031  can be performed similar to the implant test that was discussed supra. An anneal  1033  can be performed as illustrated in  FIG. 20  to repair any damage caused by the ion implantation test  1031  ( FIG. 19 ). 
         [0049]    Approximately identical two mask angular measurement apparatus (e.g., apparatus ( 1 ), apparatus ( 2 ), apparatus ( 3 ), etc., like the apparatus illustrated in  FIG. 7  would be placed successively into an ion implanter at “known” angles (e.g., −2, −1, 0, 1, 2 degrees) and the resistivity of the pillars in those apparatus would be measured to develop calibration curves for the ion implanter being tested, for example. It is also possible to measure the angles as a function of pillar resistivity using mathematical modeling as contemplated in this invention. 
         [0050]      FIGS. 22-23  illustrate yet another embodiment of the present invention according to at least one aspect of the present invention.  FIG. 22  illustrates a top down view of an ion implantation angle measurement apparatus  2200 . A high aspect ratio external mask  2202  can be held or clamped to a workpiece  2302  ( FIG. 23 ) that is non-fixedly attached to a platen using an electrostatic chuck, a clip  2204  and bolt  2206  arrangement as shown, or any suitable arrangement for holding down the workpiece  2302  ( FIG. 23 ). Slots  2308  can be cut into the mask using photolithography, laser techniques, or any other suitable methods for forming slots  2308  in the mask  2304 . The mask  2304  can be made of graphite, polysilicon, or any other suitable material compatible with semiconductor implantation. A blanket n-well may be formed within the mask  2202 , for example by performing an implantation and a damage anneal prior to the angle test implantation. The blanket n-well implantation is performed in order to create an n-type region at the surface of a p-type wafer, into which p/n junctions can be formed by test implants of p-type dopants. 
         [0051]    The high aspect ratio slots  2308  can have an aspect ratio in both the vertical and horizontal direction of approximately 20 to 1, for example. The slots  2308  can be approximately 20 microns wide and about 400 microns long with the mask  2304  having a thickness of approximately 500 microns, for example. The large spacing  2310  between slots  2308  can be greater than 500 microns wide, whereas the small spacing  2312  between slots  2308  can be approximately 500 microns. However, it should be appreciated that the slot  2208  dimensions can be any suitable length, width and depth or irregular in shape and the slots  2308  can be laid out in any suitable pattern, number of slots, and the like. In this embodiment the resistivity of the workpiece  2302  in the masked area (along the length of the regions implanted by ions passing through the slits), the resistance in the completely closed areas and the resistance in the open areas are compared against each other and calibrated measurements to determine the beam angle. The measurements can be taken using a four point probe, for example, and electrical equipment or any suitable electrical measurement means. The advantage of this apparatus  2200  is that it can be used over and over in comparing various implanters and creating various calibration curves. The mask  2202  can be precision engineered and located on the workpiece  2302  within a given accuracy and these techniques are well known by those of skill in the art. 
         [0052]    Illustrated in  FIG. 24  is another embodiment of the present invention, utilizing contacts  1 - 3 , as illustrated, and a trench  2404  fabricated in a workpiece  2402  to create an ion implantation angular measurement apparatus  2400 . The resistivity between contacts  1  and  2 , between contacts  2  and  3 , and between contacts  1  and  3  can be measured for the apparatus  2400  formed on a silicon workpiece  2402 . In measuring the resistivity between  1  and  2 , for example, because contact  1  is outside the trench and contact  2  is located in a trench, as illustrated, the current has to flow horizontally, then vertically and then horizontally again. If the ion implantation is in a vertical direction (zero degrees) then the doping of the vertical walls will be a minimum value or approximately zero, for example, and will be a high resisitivity region. Therefore, the resistivity between contacts  1  and  2  and between  2  and  3  will be high, for example. If the angle is greater than zero degrees and the angle β  2406  is as illustrated, the vertical wall between contacts  1  and  2  will be implanted by the dopant and the resistivity between contacts  1  and  2  will be lower than the resistivity between contacts  2  and  3 . By taking various measurements at various angles β  2406  for an ion implanter under test, calibration curves can be developed for the ion implantation equipment under test. 
         [0053]      FIG. 25  illustrates a similar ion implantation angular measurement apparatus  2500  to  FIG. 24 , except contact  2  is located on top of a pillar  2504  in the workpiece  2502  in  FIG. 25  rather then being located in a well as in  FIG. 24 ; however, the principles of measuring the resistivity between the various contacts are similar. In this case an ion beam  2506  is directed downward and to the left as illustrated in  FIG. 25  as angle α  2506 . In this example, a right vertical side  2510  of the pillar  2504  is implanted  2508  with ions, whereas a left vertical side  2512  is shielded from implantation  2508  by the pillar  2504 . It should be appreciated also that the contacts  1 - 3  are much smaller than those shown in  FIG. 25 . In addition, a right horizontal surface  2514  is fully implanted  2508  with ions as shown, whereas a left horizontal surface  2516  is partially blocked by the pillar  2504 . Therefore in this situation the resistivity from contact  1  to contact  2  is greater than the resistivity from  2  to  3 , for example. By utilizing various apparatus  2500  of this type, various calibration curves can be generated for each ion implantation system under test for angular accuracy. 
         [0054]      FIG. 26  illustrates pillars  2602  that utilize a fill factor in order to create an ion implantation angular measurement apparatus  2600 , according to yet another aspect of the present invention. The pillars  2602  comprise a silicon oxide  2610  or any insulating material formed on a silicon layer  2604 . A layer of photoresist  2612  is formed on the oxide layer  2610  utilizing photolithographic techniques that are well know by those of skill in the art. For example, if the pillar and the space between the pillars are equally wide that represents a fill factor of 50%. In this approach, the resistivity in the n-type silicon layer  2604  beneath the pillar is measured for resistivity and the resistivity of the pillars is not measured because the pillars are built out of insulating material. The resistivity of the workpiece silicon  2604  can then be measured using a four point probe. In  FIG. 27  the fill factor is again 50% and theoretically for a vertical implant the same resistivity will be measured in  FIG. 26  and  FIG. 27 . If however there is an angle error, the resistivity of  FIG. 26  will increase more than  FIG. 27  because the spacing  2606  in  FIG. 26  is less than in  FIG. 27  and therefore the pillars  1602  in  FIG. 26  will block more of the implanted dose into the silicon base  2604 . In a zero degree implant  2608  (a vertical implant) in  FIG. 26 and 2708  in  FIG. 27 , the resistivity of the silicon bases,  2604  and  2704  respectively, is equal because the fill factor is equal and there is the same number of pillars (assuming the width of the pillars is the same). In this approach the resistivity is measured in the bottom silicon herein, rather than in the pillars themselves. Calibration curves, as discussed supra, are again generated based upon the resistivity measured using the apparatus  2600  and  2700 . In one embodiment the apparatus bases  2604  and  2704  can be raw silicon as drawn or the bases  2604  and  2704  can be initially implanted with ions prior to the formation of the pillars  2602  and  2702 . It should be noted that the test implant can be of the same or of the opposite conductivity as the initial implantation. 
         [0055]      FIGS. 28 and 29  illustrate a top and side view of a similar embodiment to  FIG. 21  according to an aspect of the present invention. However, by providing a serpentine structure  2802  the angular measurement apparatus  2800  can measure smaller ion angle changes by measuring the current over a greater distance, for example. Recalling equation 1 discussed supra, R=rho×L/(A), if the length (L) of the apparatus is increased for the same area (A) and rho, (electrical resistance of a uniform specimen of the material, measured in ohms) therefore a higher resistivity is measured. 
         [0056]    The resistivity of the serpentine apparatus  2802  can be measured utilizing well known probing equipment. When measuring a very small resistance, the contact resistance can govern and completely obscure changes in the resistance of the angular measurement apparatus  2800 . By increasing the length of the apparatus  2800  the contact resistance measurement across contacts  2804  and  2806  can be minimized. 
         [0057]      FIG. 30  illustrates an exemplary method  3000  of a one mask process for fabrication of an angular measurement apparatus according to an embodiment of the invention. While exemplary methods are illustrated and described herein as a series of acts or events, it will be appreciated that the present invention is not limited by the illustrated ordering of such acts or events, as some steps may occur in different orders and/or concurrently with other steps apart from that shown and described herein, in accordance with the invention. In addition, not all illustrated steps may be required to implement a methodology in accordance with the present invention. Moreover, it will be appreciated that the method may be implemented in association with the apparatus and systems illustrated and described herein as well as in association with other systems not illustrated herein. 
         [0058]    The exemplary method  3000  ( FIG. 30 ) is illustrated along with  FIGS. 1-9 .  FIGS. 1-9  illustrate cross-sectional views and a top view of an exemplary angle measurement apparatus. The method  3000  begins at  3010  with forming an insulating layer  102  (e.g., silicon dioxide, a fraction of a micron thick, e.g., 0.1 −0.2 microns thick) over a handle substrate  101  (e.g., approximately 770 microns thick). In addition, at  3010  a single crystal silicon layer  104  is formed on the insulating layer  102 . Together the handle substrate  101 , the insulating layer  102  and the silicon layer  104  can be referred to as a workpiece  108 , as illustrated in  FIG. 3 . 
         [0059]    At  3012  of  FIG. 30  an ion implantation  106  is illustrated in  FIG. 2 , utilizing an ion beam, having a number of characteristics including, dopant type, dose, beam current, angle of incidence, energy, and the like. The single crystal silicon layer  104  can be implanted with n-type or p-type ions. Although the ion implantation  106  is depicted as being substantially orthogonal to a surface of the silicon layer  104 , the implantation  106  can be at other incident angles with the surface of the silicon layer  104 . Ion implantation is well known by those of skill in the art. It should be appreciated that a platen or electrostatic chuck (not shown) holds the handle substrate  101  and the platen is operable to move the workpiece  108  through the ion beam at a controlled rate, for example, so as to achieve desired implantation results. Generally, the ion implantation  106  is performed in multiple passes on the workpiece  108  through the ion beam. By so doing, a substantially uniform implantation  106  across the workpiece  108  can be obtained because all parts or portions of the workpiece  108  move through the ion beam at about the same rate. 
         [0060]    An anneal  107  ( FIG. 2 ) can be performed at  3014  after the implantation  106  to repair any damage caused by the implantation  106 , for example. Annealing processes are well known by those of skill in the art. In  FIG. 30  at  3016 , an oxide layer  110  can be formed on top of the single crystal silicon layer  104  employing thermal oxidation or deposition, for example. The formation of the oxide layer  110  is well known by those of skill in the art. 
         [0061]    At  3018 , of  FIG. 30  photoresist  112  can be deposited on the oxide layer  110  using a single mask process, for example, on a partial ion implantation angle measurement apparatus  400  illustrated in  FIG. 4 . The photoresist  112  can then be exposed  114  and etched  116 , as illustrated at  3018 , for example. The photolithographic process is carried out to remove a portion of the oxide  110  and a portion of the silicon layer. The process of photolithography in semiconductor apparatus manufacturing is well known by those of skill in the art. 
         [0062]      FIG. 5  illustrates a partial ion implantation angle measurement apparatus  500  where a pillar first layer  118  of the pillars  120  (e.g., pillars numbered  1 - 6 ) can be made out of the single crystal silicon layer  106  ( FIG. 4 ), for example. A pillar second layer  119  can be formed out of the oxide layer  110  in  FIG. 5  wherein a remaining photoresist  112  can be optionally cleaned off or stripped  122  using any photolithographic process that is well known to those of skill in the art or the photoresist can be removed in a subsequent act. It is to be appreciated that any number of pillars, two or greater can be utilized in forming an angular measurement apparatus, of various widths, spacings, heights, materials, angular orientation on the workpiece, number of layers, etc., and all are contemplated within this invention. After the photoresist  112  is stripped  122  in  FIG. 5  an optional standard clean  124  can be performed in  FIG. 6 . 
         [0063]    At  3020  of  FIG. 30  an implant test  126  can be performed at an angle θ  127  as illustrated in the cross sectional view of  FIG. 7 , for a given apparatus  700  that is being tested for a given ion implantation system and the apparatus  700  as illustrated is also shown in a top view in  FIG. 9 , for example. In the present example, six of the pillars  120  are shown (e.g., numbers  1 - 6 ) with an angular ion beam  126 , as illustrated. In this example, as described supra, the angular beam is shown directed at a clockwise angle θ  127  (e.g., from vertical). Under these conditions, pillar  6  (e.g., the right most pillar) will be the pillar with the greatest number of ions or dopant implanted  126  in a pillar first layer  118  (e.g., silicon), for example, whereas pillars  1 - 5  will be shielded from a portion of the ion implantation  126  by the pillar to their immediate right. In other words, pillar  5  is partially shielded by pillar  6 ; pillar  4  is partially shielded by pillar  5 ; and so on. Ions implanted into the second pillar layer  119  or the silicon dioxide insulating layer  102  does not change the resistivity of the pillars. Because the spacing is the same between the pillars in this example, after implantation  126  the resistivity of pillars  2  and  5  remains approximately equal, and the resistivity between  3  and  4  remains about equal, whereas the resistivity of pillars  1  and  6  is no longer equal and represents a function of the ion implantation angle θ  127 . It should be appreciated that the photoresist, if left in place, prior to the implantation at  3020 , the photoresist can be stripped at  3030 , for example. 
         [0064]    It should be noted however that because of scattering effects that are well known by those of skill in the art, there may be different readings at the center of the pillars, as opposed to pillars at the edges. This is true even after accounting for differences in the line lengths of the pillars. If the ion implantation was coming down from the top of the ion implanter in a vertical fashion there would be no difference in resistivity between the pairs of the pillars, for example. It should be appreciated that the number of pillars can be two or greater, the spacing between pillars can be non-equal and the lengths of pillars can be non-symmetrical, the pillar materials can vary from one pillar to another, and the like, and all such variations are contemplated herein. In addition, these pillars can be part of a test apparatus or part of an apparatus wafer, for example. At  3020  an optional anneal  128 , for example, can be performed to repair any damage caused by the implantation ( FIG. 8 ). 
         [0065]    Once the test implantation  126  ( FIG. 7 ) and an optional anneal  128  ( FIG. 8 ) are performed at  3020 , the resistivity of the various pillars can be measured and compared as a function of the angle of implantation. The resistivity measurements can be carried out using probe instruments and electrical test equipment that are well known by those of skill in the art. The resistivity measurements can be made one pillar at a time connecting to a single set of contacts, or with twelve pins that make contact with all of the contact pins at the same time in order to make six resistivity measurements simultaneously, manually or automatically, etc. 
         [0066]    Approximately identical single mask angular measurement apparatus (e.g., apparatus ( 1 ), apparatus ( 2 ), apparatus ( 3 ), etc., like the apparatus illustrated in  FIG. 7  would be placed successively into an ion implanter at “known” angles (e.g., −2, −1, 0, 1, 2 degrees) and the resistivity of the pillars in those apparatus would be measured to develop calibration curves for the ion implanter being tested, for example. It is also possible to measure the angles as a function of pillar resistivity using mathematical modeling as contemplated in this invention. 
         [0067]      FIG. 31  along with exemplary  FIGS. 10-21  illustrate a two mask fabrication process for manufacturing an angular measurement apparatus according to yet another embodiment of the present invention. An advantage of the angular measurement apparatus formed with two masks is that it allows the top and bottom probe pads and leads to be doped more heavily than the pillars within the middle section of the apparatus which remains lightly doped. This may be necessary for testing low and mid-dose implantations, where the pads must be heavily doped to make a low contact resistance, but the pillars can be lightly doped to adequately detect the implantation angle under test. This will be discussed in detail the following discussion. 
         [0068]    The method  3100  begins at  3110  with forming a single crystal silicon layer  1004  on a support layer  1002 . Together the single crystal silicon layer  1004  and the support layer  1002  can be referred to as a workpiece  1008 , as illustrated in  FIG. 11 . At  3112  of  FIG. 31  an ion implantation  1006  is illustrated in  FIG. 11 , utilizing an ion beam, having a number of characteristics including, dopant type, dose, beam current, angle of incidence, energy, and the like. The single crystal silicon layer  1004  can be implanted with n-type or p-type ions. Although the ion implantation  1006  is depicted as being substantially orthogonal to a surface of the silicon layer  1004 , the implantation  1006  can be at other incident angles with respect to the surface of the silicon layer  1004 . Ion implantation is well known by those of skill in the art. The apparatus in  FIG. 10-21  can also be built up on “ready made” silicon-on-insulator workpiece, for example. 
         [0069]    It should be appreciated that platen or electrostatic chuck (not shown) holds the handle substrate (not shown) and the platen is operable to move the workpiece  1008  through the ion beam at a controlled rate, for example, so as to achieve desired implantation results. Generally, the ion implantation  1006  is performed in multiple passes of the workpiece  1008  through the ion beam. By so doing, a substantially uniform implantation  1006  across the workpiece  1008  can be obtained because all parts or portions of the workpiece  1008  move through the ion beam at about the same rate. 
         [0070]    An anneal  1007  can be performed at  3114  after the implantation  1006  to repair any damage caused by the implantation  1006 , for example. Annealing processes are well known by those of skill in the art. In  FIG. 31  at  3116 , an oxide layer  1010  can be formed on top of the single crystal silicon layer  1004  employing thermal oxidation or deposition, for example. The formation of the oxide layer  1010  is well known by those of skill in the art. 
         [0071]    At  3118 , of  FIG. 31  photoresist  1012  can be deposited on the oxide layer  20   1010  using a masking process, for example, on a partial ion implantation angle measurement apparatus  1300  illustrated in  FIG. 13 . The photoresist  1012  can then be exposed  1014  and etched  1016 , as illustrated at  3118 , for example. The photolithographic process is carried out to remove a portion of the oxide  1010  and a portion of the silicon layer  1004 . The oxide  1010  in the first region ( 1020  and  1023  (FIG.  21 )), as illustrated. The process of photolithography in semiconductor apparatus manufacturing is well known by those of skill in the art. 
         [0072]    At  3120 , of  FIG. 31  implanting a high dose into a first region  1020  and second region  1023  ( FIG. 21 )) wherein the oxide layer  1010  has been removed is performed.  FIG. 21  illustrates a partial ion implantation angle measurement apparatus  2100  where a pillar first layer  1018  ( FIG. 18 ) of the pillars  120  (e.g., pillars numbered  1 - 6 ) can be made out of the single crystal silicon layer  104  ( FIG. 19 ), for example.  FIG. 14  illustrates a partial measurement apparatus  1400  with a portion of the first photoresist layer  1012  and a portion of the oxide layer  1010  removed  1015 . The process at  3118  can use any photolithographic process that is well known to those of skill in the art. 
         [0073]    Contact pads  1021  (e.g., pads numbered  1 C- 6 C and  1 D- 6 D) and leads within regions  1020  and  1023  must be heavily doped to make low resistance contacts pads  1021 . A third region  1018 , ( FIG. 21 ) is covered with a mask during the high dose ion implantation  1019  ( FIG. 16 ) to prevent doping in that region  1018 . 
         [0074]    It is to be appreciated that any number of pillars, two or greater can be utilized in forming an angular measurement apparatus, of various widths, spacings, heights, materials, number of pillar layers, angular orientation on the workpiece, etc., and all are contemplated and embodied within this invention. After the first photoresist  1012  is stripped  1017  in  FIG. 15  an optional standard clean can be performed. In  FIG. 17  as illustrated at  3124  of method  3100 , a second photoresist  1020  can be deposited, patterned and etched  1021  on an oxide layer  1010 . As illustrated in  FIG. 18  pillars  7 - 12  are now formed on the insulating layer  1002  comprising, a first pillar layer  1018  made of silicon and a second pillar layer  1010  made of oxide, for example. A second photoresist layer  1020  (i.e., second mask) can be removed or stripped  1025  at  3124  after the etching of the oxide and silicon  1023  down to the insulating layer  1002  at  3126  of  FIG. 31 . 
         [0075]    At  3130  of  FIG. 31  an ion implantation  1031  (e.g., the characterization implant) can be performed at an angle as illustrated in the cross sectional view of  FIG. 19 , for a given apparatus  1900  that is being tested for a given ion implantation system and the apparatus  1900  as illustrated is also shown in a top view in  FIG. 21 , for example. In the present example, six of the pillars are shown (e.g., numbers  1 - 6 ) with an angular ion beam  1031 , as illustrated. In this example, as described supra, the angular beam is shown directed at a clockwise angle (e.g., from vertical). Under these conditions, pillar  6  (e.g., the right most pillar) will be the pillar with the greatest number of ions or dopant implanted  1031  in a pillar first layer  118  (e.g., silicon), for example, whereas pillars  1 - 5  will be shielded from a portion of the ion implantation  1031  by the pillar to their immediate right. An optional anneal  1033  at  3132  can be performed as illustrated in  FIG. 20  to repair any damage caused by the ion implantation test  1031  ( FIG. 19 ). 
         [0076]    Approximately identical two mask angular measurement apparatus (e.g., apparatus ( 1 ), apparatus ( 2 ), apparatus ( 3 ), etc., like the apparatus illustrated in  FIG. 7  would be placed successively into an ion implanter at “known” angles (e.g., −2, −1, 0, 1, 2 degrees) and the resistivity of the pillars in those apparatus would be measured to develop calibration curves for the ion implanter being tested, for example. It is also possible to measure the angles as a function of pillar resistivity using mathematical modeling as contemplated in this invention. 
         [0077]      FIG. 32  illustrates an exemplary method  3200  of forming an ion implantation angle measurement apparatus  2200  ( FIG. 22 ) according to the present invention. While exemplary methods are illustrated and described herein as a series of acts or events, it will be appreciated that the present invention is not limited by the illustrated ordering of such acts or events, as some steps may occur in different orders and/or concurrently with other steps apart from that shown and described herein, in accordance with the invention. In addition, not all illustrated steps may be required to implement a methodology in accordance with the present invention. Moreover, it will be appreciated that the methods may be implemented in association with the apparatus and systems illustrated and described herein as well as in association with other systems not illustrated. 
         [0078]    The method  3200  begins with supplying an oxide mask of diameter approximately equal to workpiece at  3210 . An exemplary result of performing method  3200  is illustrated in  FIGS. 22 and 23 .  FIG. 22  illustrates a top view of an exemplary ion implantation angle measurement apparatus  2200  having slots  2208 . A high aspect ratio external mask  2202  can be held or clamped to a workpiece  2302  ( FIG. 23 ) that is non-fixedly attached to a platen using an electrostatic chuck, a clip  2204  and bolt  2206  arrangement as shown, or any suitable arrangement for holding down the workpiece  2302  ( FIG. 23 ). A photoresist is deposited over the surface of the mask  2200  at  3212  wherein a masking pattern at  3212  can be created associated therewith. As will be understood by one of ordinary skill in the art, the photoresist is then exposed to a predetermined wavelength of radiation through a masking reticle (not shown), and developed in a conventional developing solution to form the slots  2208  illustrated in  FIGS. 22 and 23  utilizing an etching process at  3216 , for example. The slots  2208  are further etched into the mask at  3218  and are further characterized by a width and a length and the slots  2208  create openings in the mask  2300 , as illustrated in  FIG. 23 . 
         [0079]    At  3220  the mask  2202  can be non-fixedly attached to a workpiece  2302  ( FIG. 23 ) utilizing fasteners, clamps, and the like. At  3222  the workpiece can be implanted with an ion beam set to a pre-determined angle on the implanter. At  3226  the mask can be removed from the workpiece  2302  and the resistivity of the workpiece can be measured using a four point probe, for example. At  3228  calibration curves can be developed based upon the set angle and the angle based upon the measured resistivity. 
         [0080]    It is appreciated that alternate aspects of the invention include any suitable number of pillars located at other positions, and with other aspect ratios and materials is contemplated herein. 
         [0081]    Although the invention has been illustrated and described with respect to one or more implementations, equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described components (assemblies, apparatus, circuits, systems, etc.), the terms (including a reference to a “means”) used to describe such components are intended to correspond, unless otherwise indicated, to any component which performs the specified function of the described component (e.g., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary implementations of the invention. In addition, while a particular feature of the invention may have been disclosed with respect to only one of several implementations, such feature may be combined with one or more other features of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms “including”, “includes”, “having”, “has”, “with”, or variants thereof are used in either the detailed description and the claims, such terms are intended to be inclusive in a manner similar to the term “comprising.”