TWI383458B - Dose cup located near bend in final energy filter of serial implanter for closed loop dose control - Google Patents

Description

a dose cup for closed loop dose control near the bend in the last energy filter of the series ion implanter

The present invention relates generally to an ion implantation system, and more particularly to a system and method for ion dose measurement and compensation for the occurrence of photoresist gas release, pressure and ion source fluctuations in a tandem ion implanter.

In the fabrication of semiconductor devices, ion implantation is used to incorporate impurities into the semiconductor. An ion beam implanter processes an enamel wafer with an ion beam to produce an n- or p-type foreign material doping or form a passivation layer during fabrication of an integrated circuit. When used to dope a semiconductor, the ion beam implanter injects a selected ion species to produce the desired foreign material. Implantation of ions from materials such as germanium, arsenic or phosphorous can yield "n-type" foreign material wafers, and if "p-type" foreign material wafers are required, they can be implanted by means of boron. The ions produced by the source material of gallium or indium.

A typical ion beam implanter includes an ion source for generating positively charged ions from an ionizable source material. The generated ions will constitute an ion beam and will be directed to an implantation station along a predetermined ion beam path. The ion beam implanter can further comprise a structure of ion beam formation and shaping extending between the ion source and the implantation station. The ion beam forming and shaping structure maintains the ion beam and limits the passage of the ion beam through the extended lumen or channel of the implantation station. When an implanter is operated, the channel is typically evacuated to reduce the probability of ions deviating from the predetermined ion beam path as a result of impacting the air molecules.

The mass of an ion relative to a charge (e.g., charge to mass ratio) affects the extent to which both of it is axially and laterally accelerated by an electrostatic or magnetic field. Thus, the ion beam arriving at the desired region of a semiconductor wafer or other target can be extremely pure, since ions of undesired molecular weight can be deflected away from the location of the ion beam and implants other than the desired material can be avoided. . The process of selectively distinguishing between desired and undesired charge versus mass is referred to as mass analysis. The mass analyzer usually uses a mass analysis magnet, which generates a bipolar magnetic field to deflect various ions in the ion beam by magnetic deflection in an arc channel, thus effectively distinguishing the charge ratios with different masses. Ions.

Dose measurement is the measurement of ions implanted in a wafer or other workpiece. When controlling the dose of implanted ions, a closed loop feedback control system is typically used to dynamically adjust the implant to achieve uniformity in the implanted workpiece. This control system utilizes instantaneous ion flow monitoring to control the slow scanning speed of an implanter. A Faraday or Faraday cup periodically measures the ion beam current and adjusts the slow scan speed to ensure a fixed dose. Frequent measurement operations allow the dose control system to quickly respond to changes in the ion beam flow. The Faraday cup can be stationary, well shielded, and located close to the wafer, making it extremely sensitive to ion beam currents doping the wafer. However, the Faraday cup only measures the current portion of the ion beam current.

The interaction between the ion beam and the gas evolved during implantation can cause the current (a charge stream) to change, even when the particle stream (a doped stream bundle) is stationary. To compensate for this effect, the dose controller can simultaneously read the ion beam from the Faraday cup and read the pressure from a pressure gauge. When a pressure compensation factor is calibrated for an implant formulation, the measured ion beam current is modified by the software to provide a compensated ion beam stream signal to the circuitry that controls the slow scan. Thus, the amount of compensation in such a closed loop system (e.g., in the compensated ion beam current signal) can be a function of both the ion beam current measured at the Faraday cup and the pressure.

After appropriate application, pressure compensation can improve repeatability and uniformity over a wide range of implant pressures. However, the vacuum inside an implanter is never perfect. There will always be some residual gas in the system. Usually the residual gas does not cause problems (in fact, a small amount of gas contributes to good ion beam transport and effective charge control). However, for example, at a sufficiently high pressure, the increased pressure due to the release of the photoresist gas, the exchange of charge between the ion beam and the residual gas can cause dose measurement errors. For example, the dose displacement between the implanted bare wafer and the wafer implanted with photoresist (PR) is unacceptably large, or if the dose uniformity is significantly degraded, pressure compensation can be used to improve uniformity.

The charge exchange reaction between the ion beam and the residual gas can increase or decrease electrons to the ion and change the state of charge of the ion in the desired value of the formulation. When the charge exchange reaction is neutralized, a portion of the incident ion stream is neutralized. The result is a decrease in current while the particle flow (including the neutralizer) remains unchanged. When the charge exchange reaction is electron stripping, a portion of the ion stream loses electrons. The result is an increase in current while the particle flow remains the same.

For a typical formulation, where charge exchange is an important point, the ion beam is often more neutral and not stripped. Therefore, whenever the pressure at the end station increases, the ion beam current measured by the Faraday cup decreases. The ions in the ion beam are neutralized, but these are not deflected or stopped by the residual gas. After the magnet is analyzed, the dose rate (i.e., dopant atoms per area per time) is not altered by charge exchange. The implanted neutralizer contributes to the dose received by the wafer but is not measured by the Faraday cup. Therefore, the wafer will be administered an excessive dose.

Pressure compensation can therefore be employed whenever the charge exchange between the ion beam and the residual gas in the processing chamber has a significant effect on the dose. The pressure at which this occurs will depend on the formulation and the processing specifications. For some formulations, when the pressure due to the release of the photoresist gas is measured at 5x10 ^{- 6} torr at the pressure gauge, compensation is required to meet the implant specification. For most formulations, where the pressure due to the release of photoresist is 2x10 ^{- 5} torr or more, compensation can be considered. Such compensation can include measuring the effects of photoresist gas release by implanting a wafer with or without photoresist, and comparing the measured changes to processing specifications. The amount of compensation required will depend on the pressure that the dose controller reads from a pressure gauge during implantation.

In addition, changes in the ion source output itself may result in some ion beam flux variation measured at the dose cup. The measurement of the ion cup source at the wafer is also affected by the neutralization resulting in the ratio of the measured current and the pressure change of the gas release as described above. It is necessary to compensate for the true rate of change in the ion beam in the wafer, which would require the system to change the beam current due to changes in the source output and the charge exchange of gases in the ion beam path. Change to distinguish. Therefore, using this dose cup measurement to correct or compensate for the dose rate may encounter significant obstacles due to these variables.

Thus, improved systems and methods are needed to achieve a uniform dose rate in an ion implanter in the event of a change in ion beam current due to ion source and wafer gas evolution, without associated use Additional complexity and cost of pressure measurement and pressure compensation operations.

The present invention is directed to a proper ion current measurement operating system and method for providing a dose for an ion implantation system associated with a wafer dose. In accordance with the present invention, the ion implantation system has a dose cup located adjacent the last energy bend of the scanned or striped ion beam of a tandem implant. The system includes an ion implanter having a source of charged particles for generating a ribbon ion beam. The system further includes an angular energy filter (AEF) system configured to filter the energy of the strip-type ion beam using a last energy bend within the ion beam. The AEF system further includes an AEF dose cup, which is preferably immediately after the last energy bend of the ion beam for proper measurement of the ion beam ion current. The AEF system directs the ion beam along an ion beam path in a downstream direction toward the target wafer of the end station. The AEF system is defined by a chamber or AEF chamber in which each AEF element resides upstream of the processing chamber or end station. Downstream of the end station of the AEF system is defined by a chamber in which the wafer or workpiece is fixedly placed to move relative to the strip-type ion beam, and ions are implanted into the wafer.

The AEF system can include a pump process to maintain a lower pressure near the AEF than at the end station where gas is generated. The AEF system can be separated from the end station by an opening that restricts airflow, thereby providing a pressure differential between the AEF chamber and the end station processing chamber.

In one feature of the invention, the AEF dosing cup is preferably located upstream of the end station adjacent to the last energy bend in the AEF system to mitigate gas release from the wafer implant operation. The pressure of life is mutated. Thus, the system provides correct ion current measurements without the need for pressure compensation before such gases produce a significant amount of neutral particles in the ion beam. Such dose measurements can also be used to affect the scanning speed to ensure uniform closed loop dose control when ion beam current changes occur from the source of the ions and the release of gas from the wafer.

According to a feature of the invention, the ion beam can comprise a scanning or a continuous strip of ion beam.

In another feature of the invention, the plane of the last energy bend at the ion beam is orthogonal to the strip-type ion beam plane.

According to still another feature of the invention, the AEF system is located in the AEF chamber region upstream of the end station, and further reduces the pressure in the AEF chamber by a pump, thereby reducing gas release and The effect of other pressure sources on the AEF dose cup.

In one feature of the invention, although the AEF dose cup is located adjacent to the last energy bend of the AEF chamber and upstream of the end station, and no pressure compensation is employed, in another feature of the invention, the ion implant The inlet system further includes pressure compensation to further refine the AEF dose cup measurement.

In yet another feature of the invention, the AEF dose cup is in an overscan area associated with the wafer or workpiece being scanned by the strip ion beam.

In another feature of the invention, the reading from the profiled cup at about the plane of the wafer during an implantation process is compared to the result of the AEF cup to infer the difference in charge exchange rate between the two locations. The value, by which the number of neutral particles produced over the corresponding path length can be determined.

When the wafer is transferred to the system according to the present invention, although most of the particles becomes neutral, then the AEF dose cup, measured from the ions I _will be proportional to the _measured particles in the flow entering the wafer stream I _{into the implant,} according to this system: (1) I = I _{of the implant measured} * _{C P} * C C C, wherein C _P is a factor, can be corrected to the charge exchange in the ion beam Sex or a ratio of higher charge states as defined below; and C _{C C} is a proportionality constant based on the ion current measured at the AEF dose cup relative to the ion current measured near the plane of the wafer ( The ratio of the profiled cup at the wafer, for example, is determined during the dosing cup calibration process in the initial implant settings for each formulation.

(a) the pressure in the AEF region is maintained sufficiently low, and in the case where the charge exchange on the short path between the AEF bend and the AEF cup is a small fraction of the true ion current, assuming C _P is equal to 1. This is expected to cover most formulations of a medium ion flow tool.

under (b) or another person, the pressure within the AEF area sufficiently high and sufficient to affect I _{A E F} = I _measured * _C C C to require correction cases may be utilized as the current high ion flow tool for Perform a _{P P} =exp(K*P _{A E F} ) to pressure compensate the AEF cup reading. In this case, the ion beam current measured in the Faraday cup for dose control can be plotted as a function of pressure as the pressure is increased over a desired range, and K is determined empirically, for example in Austria. Mike Halling, Alpbach's "2000 International Conference on Ion Implantation Technology", is described in the IEEE lecture "TWo Implant Measurement of Pressnre Compensation Factors" (2000) 585. Measured ion beam current with respect to the pressure of the drawing may be adapted to a I ₀ = I _measured * exp (K * P) function, where I ₀ is the ion flow at zero pressure, and K is the best The factor that fits the data.

(c) A third alternative is to compensate for the charge exchange using the difference between the ion currents in the AEF cup and the cup in the end station. In this case, C _P =1+((I _{A E F} -I _{E s} )/I _{A E F} )*(L _{A E F} /(L _{E s} -L _{A E F} ))*(P _{A E F} /P _{E S} ), where I _{A E F} is the AEF cup and the ion current I _{E s} corrected by the set cup calibration operation is the ion current L corrected by the set cup correction operation measured by the end cup _{A E F} is the distance L _{E s} from the AEF bend to the AEF cup on the name is the distance from the AEF bend to the end station cup P _{A E F} is the pressure P measured in the AEF chamber _{E s} is the pressure measured in the end station in such a manner as to correct the AEF cup ion current over a shorter distance than the end station cup and the charge exchange affects its reading, which is by A factor (L _{A E F} /(L _{E s} -L _{A E F} )) is completed. This also allows for the lower pressure in the AEF region to correct for the shorter distance, which is done by a factor (P _{A E F} /P _{E s} ). These two factors are applied to the proportional change in the ion beam flow between the two cups ((I _{A E F} -I _{E S} )/I _{A E F} ). This approach provides non-empirical pressure compensation.

To the accomplishment of the foregoing disclosure, the present invention includes the features which are fully described below and which are specifically indicated in the scope of the claims. Some exemplary features of the invention are described in detail below with reference to the drawings. However, these features are merely illustrative of several of the various ways in which the principles of the invention may be employed. Other characteristics, advantages, and novel features of the invention are apparent from the Detailed Description of the invention as claimed.

The invention will now be described with reference to the drawings, in which like reference numerals are used throughout the claims The present invention provides a system and method for providing a correct ion current measurement result relating to a wafer dose used in an ion implantation system. This application may include dose measurements, data logging, and feedback to the system to facilitate closed loop control of, for example, the speed at which a wafer slowly scans the mobile drive.

Dose control at high pressures in the processing chamber, particularly due to photoresist gas release, when a portion of the ion beam has been neutralized in the path to the wafer, a requirement is required to determine the effective implant The mechanism of the ion beam flow. Traditionally, this is done by measuring the pressure in the ion beam path and estimating the neutral portion by the charge exchange rate determined by pressure and known or empirical means to correct the wafer in the end station. The ion flow measured by the location is achieved. These measurement and estimation techniques are extremely cumbersome and costly, and may introduce additional inaccuracies into the final dose determination operation, particularly associated with ion beams from the ion source and gas released from the wafer. Flow changes.

The ion implantation system of the present invention incorporates a final energy filter having a final energy bend and a scanned or striped ion beam to provide a new starting point for the ion beam. That is, from the last energy bend, the ion beam will be substantially free of neutrals in the ion beam directed toward the wafer. According to one feature of the invention, a Faraday dose cup is placed after a final energy bend, and the bend is orthogonal to the plane of the strip ion beam. In this manner, the ion current is measured before there is a significant opportunity to produce a neutral in the path leading the wafer toward the wafer. Thus, the cup flow measurement operation near the last energy bend eliminates the need for pressure compensation of the measured ion current under most implant conditions. In contrast, dose cups in the end station or chamber area can be significantly adversely affected by the release of photoresist gas.

Referring now to the drawings, Figures 1 and 2 illustrate an ion beam implantation system as set forth at 100 in which various features of the present invention can be implemented. The system 100 includes an ion implanter 102 for providing ions that form a scanned or striped ion beam 104, each ion filtering and redirecting a final energy ion beam 114 using a final energy bend. An ion angular energy filter (AEF) system 110 travels through an ion beam path for implantation in a workpiece or wafer 118 at an end station 120. In the present invention, the terms "wafer" and "workpiece" are used interchangeably.

The AEF system 110 includes a pair of deflecting plates 122 that can electrostatically (or otherwise magnetically) bend the charged ions of the scanned or striped ion beam 104 to produce a selective final energy source. An ion beam 114 is obtained. The pressing electrode 124 of the AEF system 110 terminates the potential field of a positive charge deflecting plate so that electrons are not pulled from the end station 120. The AEF system 110 further includes an AEF dose cup 128 located immediately after the last energy bend of the ion beam to properly measure the ion current. The last energy bend of the AEF system can further be used to direct the energy filtered ions along an ion beam path in a downstream direction toward the target wafer 118 held by the electrostatic clamp 130 in the end station 120. Beam 114.

3 illustrates a schematic diagram 300 of a plurality of system components and an area viewed from the energy filtered ion beam 114 as scanned by the ion beam of the ion system of FIGS. 1 and 2. The strip of ion beam 114 impinges on a wafer 118 that is held by the end station 120 or another such implanted chamber, such as a translating dish-shaped electrostatic clamp 130. Although illustrated as a translational clamp 130, it should be understood that the present invention is equally applicable to a wide variety of clamp movements, including rotation, translation, and a "series" of ion beam implanters, ie, which will guide The ion beam 114 scans the surface of a stationary workpiece 118. The translation "slow scan" or "y" shift 330 of the wafer 118, along with the "x" width of the scan or strip ion beam 114, provides a larger scan area 310 covering the entire wafer 118. The area that is not used or scanned by the wafer is referred to as an overscan area 320, which can be used as a dose measurement.

In accordance with the present invention, the strip ion beam 114 will also impinge on the AEF dose cup 128 of FIG. 2 in the path to the wafer 118 immediately after the last energy bend. Figure 3 illustrates that the AEF dose cup 128 utilizes an overscan area 320 and therefore does not interfere with the ion beam striking the workpiece. Unlike conventional systems that place the dose cup at or near the wafer, the ion implantation system 100 of the present invention provides the AEF dose cup 128 of the AEF system 110 in an AEF chamber, either at the end station or The implant chamber is very upstream, thereby alleviating the gas release and ion exchange problems in question. In addition, by having the dose cup 128 immediately after the last energy bend, the neutral ions have been removed from the ion beam and only a very small amount of ion beam neutralization occurs, thereby allowing the measured current Approximate results for a very accurate implant flow. The AEF dose cup 128 is depicted on the right side of the ion beam overscan region 320 in this example, although it should be understood that in the present invention, the AEF dose cup 128 can be placed using the left or right side of the ion beam overscan. Like the dose cup alternative position 128a.

4 illustrates a selected final energy filter element of an exemplary ion beam implant system 400 in accordance with the present invention. An implanter (e.g., 102 of Figures 1 and 2) can be used to provide a scanned or striped ion beam 104. The ion beam 104 enters an angular energy filter AEF system 110 where it is bent between a deflecting plate 122 comprising a positive potential plate 122a (e.g., +25 kV) and a negative potential plate 122b (e.g., -25 kV). ) the ion beam. The ion beam 104 is then passed through a pressing electrode 124 for terminating the positive potential deflecting plate 122a and absorbing the energy of the neutral portion of the ion beam. The ion current within the ion beam 104 is then measured by the AEF dose cup 128 in the AEF system 110 immediately after the energy at the plate 122 is bent, and before being directed downstream toward the end station 120. . The AEF dose cup 128 will measure the ion current associated with the last energy of the ion beam 104 before the ion beam travels a significant distance of the ion beam path toward the workpiece and before encountering a continuously increasing ion exchange rate. . As such, more accurate dose measurements can be obtained with respect to the results of typical measurement operations performed at or about the wafer.

When the AEF dose cup 128 measures ion flow within the overscan region (e.g., 320 of Figure 3), the left or right (or both) of the ion beam overscan can be utilized to place the dose cup 128, such as The dose cup replaces position 128a.

The ion beam implant system 400 further includes various components within the end station 120 defined by an implant chamber wall. The energy filtering aperture 440 further defines the height and is thus the energy band of acceptable ions in the ion beam 114 of the wafer 118. The system 400 can be calibrated at the implant setting using a profiler or profiled dose cup 442 at or near the wafer plane.

5A and 5B illustrate, in a schematic manner, a top view and a right side view, respectively, of an ion beam path and a plurality of possible dose cup positions for monitoring ion current during implantation using an ion beam implant system 500 in accordance with the present invention. . The system 500 generates a scanned or striped ion beam 502 from an ion source, wherein in an example the ions within the ion beam are uniformly shaped and accelerated by a P lens and an accelerating tube 503, to a more High energy state or a lower energy state. The ion beam 502 then enters an angular energy filter system 504 that is configured to filter the energy of the ion beam 502. For example, a substantially positively charged ion beam 502 is bent by a deflecting plate 506 (e.g., around a nominal bending axis 505) at an angle corresponding to the final energy state and desired direction (e.g., a 15[deg.] angle). The positive deflecting plate is oriented away from the negative deflecting plate. Although a 15° deflection angle is illustrated and discussed herein, it should be understood that any angle and corresponding energy may be utilized in accordance with the present invention.

After the ion beam has been bent by the deflecting plate 506, the ion beam 502 will then pass through a pressing electrode 507 that terminates the positive potential deflecting plate (e.g., 122a) and absorbs the neutral portion of the ion beam 502. . The ion current within the ion beam 502 is then measured by the AEF dose cup 508 within the AEF system 504 after being directed toward the downstream of the end station 510. The AEF dose cup 508 will measure the ion current associated with the last energy of the ion beam 502 before the ion beam travels a significant distance through the ion beam path toward the workpiece 512. After the AEF system 504, the ion beam 502 exits the AEF system 504 within the AEF chamber section and travels downstream of the ion beam path into the end station 510. In the evacuated implant chamber of the end station 510, the ion beam enters an electronic torrent assembly (EF) 514 that controls the electronic charge on the wafer 512. The EF 514 can also optionally include one or more associated dose cups 516 that can be used to monitor the overscanned ion current within the end station 510. The ion beam 502 then strikes the wafer 512, a distribution profile cup 518 for measuring the flow across the wafer 512, and finally a harmonic flag for measuring the overscan or scan ion beam current. Plate 520, while adjusting the ion beam optics to the desired value prior to implantation.

During the set up process, the ion current measured in the dose cups 508 and 516 and the flow measured by the distribution contour cup 518 as it passes through the scanned ion beam near the wafer plane are initiated prior to implantation. Beam comparison. Since the implantation has not yet started, there will be only a slight correction for the difference in charge exchange between the cups at this time, but the difference in these positions may be due to flow changes and between these dose cup positions. The difference in ion beam transport at the wafer location causes a small difference in ion current. The factors C _{C C} =I _{P - c u p} /I _{A E F} measured in the cup calibration in equation (1) correct these effects. A similar factor C _{C C '} = I _{P - c u p} / I _{E S is} used to correct the end station cup 516. This calibration process ensures that the measured ion current at the dose cup 508 or 516 is properly scaled to represent the ion current at the wafer and can be used correctly without significant pressure changes. Control the dose.

During implantation, as charged ions travel through the ion beam path 502, they encounter collisions with charge exchanges of lost gas molecules. Although this effect is minimized in the present invention, some portions of the ions are neutralized and are not calculated by the dose cup 508 or 516. Therefore, the measured ion beam current may not fully reflect the true doped stream at the wafer 512. However, one of the methods a, b or c as described above can be applied to the AEF dose cup reading during implantation to correct the charge exchange effect on the ion beam flow.

To minimize the effect of gas release at the wafer, the AEF dose cup 508 will be located as far as possible from the end station, as in a portion of the system, such as an AEF chamber with a better vacuum. However, for example, or using a proportionality constant C _P to consider after the bending becomes neutral to contribute to the portion of the ion implantation dose, the implantation dose to obtain the true level.

For example, for most implant treatments, the lower pressure rise in AEF and the shorter distance for charge exchange can maintain a charge-influence in the AEF dose cup that is negligibly small enough, and C _P =1 given appropriate dose control.

On the other hand, if experience shows that some implants will result in a higher gas release level, such that the pressure in the AEF region is sufficiently high to significantly affect the AEF dose cup reading, then two can be used as before ( Any of the methods used to derive the C _P shown in b) and (C) to correct this situation. This conclusion can be determined in one of several ways: 1) The dose accumulated in a wafer covering the photoresist can be different from the bare wafer implanted by the same formulation to about 1% or more. Or non-uniformity in the dose of a photoresist-covered wafer, because when the ion beam sweeps over the middle of the wafer, it will take less time on the slow scan end of the wafer. More gas is released. 2) A significant change in the reading of the AEF cup flow associated with this AEF pressure change during implantation will indicate that the ion flow reading is affected by charge exchange rather than source output changes. 3) A significant change in the end station dose cup 516 associated with a small change in the AEF dose cup reading would coincide with the charge exchange in the path toward the wafer.

FIG. 6 illustrates another exemplary ion beam implant system 600 in accordance with the present invention. The system 600 further illustrates an ion beam 602 path of the system 600 of the angular energy filtering system 604 in the region of the AEF chamber 607 that is resident upstream of the end station 610 within the implant processing chamber 612. The ambient gas within the end station 610 can be isolated from the AEF chamber 607 by a vacuum isolation valve 614. During operation, the pressure within one of the chambers can be reduced by vacuum or low temperature pumps such as vacuum pump 620 and two low temperature pumps 622. In one embodiment of the invention, the pressure within the AEF chamber 607 can be lowered below the pressure within the end station 610 to reduce the effects of gas release and other sources of pressure on the AEF dose cup.

Similar to the system previously described, the system 600 produces a scanned or striped ion beam 602 from an ion source that is accelerated or decelerated by an accelerating tube 626 as needed. The ion beam 602 then enters an angular energy filter system 604 that is configured to filter the energy of the ion beam 602. For example, the positively charged ion beam 602 will be oriented at an angle corresponding to the final energy state and the desired direction (e.g., 15°), and a deflecting plate 630 is bent away from the positive deflecting plate 630a. The negative deflecting plate 630b. The ions having the desired energy within the ion beam 602 are now deflected to a desired ion beam path trajectory through the pressed electrode 632 to the AEF dose cup 634 of the AEF system 604 near the AEG bend. The energy of the unfolded neutral particles can be absorbed by a neutral ion beam trap 636 behind the pressed electrode. The AEF dose cup 634 can then be placed after the neutral ion beam rejector. Excessive energy ions are filtered (captured) by a high energy contaminant rejector 638, while too low energy ions are filtered out by a low energy contaminant rejector 640 (shown in two places) ).

Next, the obtained ion beam 602 having the desired energy, together with a portion of the neutral particles formed in the ion exchange after the last energy bend, impinges on the crystals implanted into the processing chamber 612 at the end station 610. The wafer 642 is sandwiched by the circular support structure 644. The wafer support structure 644 can be used to perform rotational and/or translational movement of the wafer relative to the scanned or striped ion beam 602.

During the production process, that is, when the semiconductor wafer workpiece 642 is collided by the ion beam 602 and thereby implanting ions, the ion beam 602 will travel from the ion source (not shown). A vacuum path is taken to the implantation chamber 612 which is also evacuated. The ion beam 602 will strike the wafer workpiece 642 as the wafer workpiece rotates and/or translates (e.g., 330 of FIG. 3). In accordance with a feature of the present invention, the translational velocity of the wafer support structure 644 can be controlled by a closed loop of control electronics (not shown) provided by feedback from the AEF dose cup 634 measurements ( The ion dose received by the workpiece 642 is determined, at least in part.

Figure 7 illustrates an exemplary AEF system 704 suitable for use in the ion beam implantation system of Figures 1-6 in accordance with the present invention. The AEF system 704 has a mount 705 that can be mounted on the right or left side of the AEF chamber wall 707. The AEF system 704 includes a deflecting plate 730, which typically applies a high voltage potential (e.g., +/- 25 kV) to the positive and negative deflecting plates of 730a and 730b, respectively, to deflect as shown. Electron ion beam 702. In this implementation, the ion beam 702 is bent about 15° downward in a downward direction relative to a horizontal ion beam path before continuing downstream to the end station and the wafer workpiece, and by pressing the electrode 732 to an AEF dose cup 734. Similar to other elements of the AEF system 704, the AEF dose cup 734 can also be secured to the mount 705 or placed on the side or rear wall of the AEF chamber 707.

It is an object of the present invention to take into account other factors such as maintaining a uniform deflection field within the AEF, placing the AEF dose cup 734 as close as possible to the last energy bend of the AEF system 704. Thus, the purpose of this positioning is to provide the shortest possible path for ion exchange prior to dose measurement, and to place the dose cup 734 at a position that reaches the most likely vacuum to minimize ion exchange collisions. In addition, the purpose is to place the AEF dose cup 734 as far away as possible from the wafer, which is the main source of pressure due to the release of photoresist gas, thereby thereby adversely affecting the ion of the dose measurement. Exchange collision opportunities are minimized. The AEF system 704 further includes another set of pressing electrodes 740 to suppress electrons from exiting the AEF region toward the accelerating tube.

Thus, in the system of the present invention, a dose cup is placed adjacent to the last energy bend of the AEF to measure the length of the path long before the majority of the path length of the trip is maintained sufficiently long to complete the ion beam path The inside of the bend reaches the ions of the wafer. In this manner, the ion stream will be proportional to the ion current entering the wafer and will experience a significantly lower charge than the previously used dose cup for this purpose in the end station. exchange. The proportionality constant C _P discloses two kinds of methods may be determined by one person, while the pressure is sufficient to compensate for changes need to be corrected. Next, during implantation, the C _P and the AEF dose measurement can be utilized to determine a true implant dose that is proportional to the AEF dose measurement, such as shown in the previous equation (1). Thus, for example, as previously described, other dosage cups such as those shown at 516 of Figure 5A may not be necessary.

A pump can be placed in the AEF chamber (e.g., 607, 707) to maintain the pressure in the AEF chamber below the pressure in the processing chamber 612 to further reduce the release of photoresist gas to the AEF dose cup. influences.

Thus, a dose cup located at the last energy bend of the scanned or striped ion beam can be used for correct dose measurement or for closed loop dose control. Such control can be used to affect the scanning speed to ensure that there is a uniform dose in the event of, for example, a change in ion beam current from the ion source output or in the presence of gas evolution from the wafer.

The present invention has been shown and described with respect to certain applications and implementations, and it should be understood that equivalents and modifications may be made by those skilled in the art. In particular, with respect to the various functions performed by the various elements (assembly, device, circuit, system, etc.) described above, the terms used to describe such elements (including references to "institutions") correspond to (unless otherwise indicated) Any element of the calibrated function of the element (i.e., functionally equivalent), even if it is not structurally equivalent to the disclosed structure for performing the function in the exemplary embodiments of the invention described herein.

In addition, although a particular feature of the invention has been disclosed by reference to one of the various embodiments, these features may be combined in other ways as desired and advantageous for any given or particular application. One or more other features of the implementation. In addition, these terms are similar to "including" in the context of the use of the terms "including", "including", "having", "owning" and the meaning of such changes in the detailed description or the scope of the patent application. The word is the same as the one that contains the nature.

100. . . Ion beam implantation system

102. . . Ion implanter

104. . . Scanning or strip ion beam

110. . . Angular Energy Filter (AEF) System

114. . . Final energy ion beam

118. . . Workpiece or wafer

120. . . End station

122. . . Deflection plate

122a. . . Positive potential plate

122b. . . Negative potential plate

124. . . Pressed electrode

128. . . AEF dose cup

128a. . . Dosing cup alternative position

130. . . Electrostatic clamp

300. . . The area viewed from the energy filtered ion beam

310. . . Scan or stripe ion beam "x" width

320. . . Overscan area

330. . . Pan "slow scan" or "y" move

400. . . Ion beam implantation system

440. . . Energy filtration pore

442. . . Distributed contour dose cup

500. . . Ion beam implantation system

502. . . Scanning or strip ion beam

503. . . P lens and accelerating tube

504. . . Angular energy filter system

505. . . Name bending axis

506. . . Deflection plate

507. . . Pressed electrode

508. . . AEF dose cup

510. . . End station

512. . . Workpiece

514. . . Electronic torrent assembly (EF)

516. . . Dosing cup

518. . . Distribution contour cup

520. . . Harmony flag board

600. . . Ion beam implantation system

602. . . Scanning or strip ion beam

604. . . Angular energy filtration system

607. . . AEF room

610. . . End station

612. . . Implant processing chamber

614. . . Vacuum isolation valve

620. . . Vacuum pump

622. . . Low temperature pump

626. . . Acceleration tube

630. . . Deflection plate

630a. . . Positive deflecting plate

630b. . . Negative deflection plate

632. . . Pressed electrode

634. . . AEF dose cup

636. . . Neutral ion beam trap

638. . . Excessive energy pollutant disposer

640. . . Low energy pollutant disposer

642. . . Wafer

644. . . Wafer support structure

702. . . Ion beam

704. . . AEF system

705. . . Mounter

707. . . AEF chamber wall

730. . . Deflection plate

730a. . . Positive deflecting plate

730b. . . Negative deflection plate

732. . . Pressed electrode

734. . . AEF dose cup

740. . . Pressed electrode

1 is a functional block diagram of an ion beam implantation system of the present invention; FIG. 2 is a top view of selected components of the ion implantation system of FIG. 1 and a scanning or strip ion beam; FIG. 3 is a diagram 1 And a selected portion of the implant system and an ion beam path pattern of the region scanned by the ion beam; FIG. 4 is a perspective view of a selected final energy filter element of an exemplary ion beam implant system of the present invention; And 5B are respectively a top view and a right side view of the ion beam path of the ion beam implantation system of the present invention and a plurality of possible Faraday cup positions; FIG. 6 is a final energy bend of the exemplary ion beam implantation system of the present invention, an AEF The system components and the ion beam path in an end station simplify the right side view; Figure 7 is a simplified right side view of an exemplary AEF system suitable for use in the ion beam implantation system of Figures 1-6.

100. . . Ion beam implantation system

102. . . Ion implanter

104. . . Scanning or strip ion beam

110. . . Angular Energy Filter (AEF) System

114. . . Final energy ion beam

118. . . Workpiece or wafer

120. . . End station

122. . . Deflection plate

124. . . Pressed electrode

128. . . AEF dose cup

130. . . Electrostatic clamp

Claims (38)

An ion implantation system comprising: an ion implanter configured to generate a ribbon ion beam; configured to filter the strip by bending the ion beam at a final energy bend An angular energy filter (AEF) system of the energy of the ion beam; an AEF dose cup associated with the AEF system configured to generally measure the ion beam current at the last energy bend; and the AEF system One of the downstream end stations, defined by a chamber, wherein a workpiece is fixedly positioned for movement relative to the strip-type ion beam, and ions are implanted therein; wherein the AEF dose cup is at The exterior of the chamber of the end station. The system of claim 1, wherein the AEF system comprises: a pair of deflecting plates for deflecting the ion beam by a target deflection angle, thereby defining a correspondence from an original path The final energy level of the ion beam at a biased angle; a set of pressed electrodes downstream of the deflecting plates, the pressed electrodes being configured to terminate a positive potential imparted to the ion beam by the deflecting plates And an ion beam rejecting plate for absorbing energy in the ion beam that is not deflected by the deflecting plates by the deflecting plates; and the AEF dose cup is immediately at the last energy bend of the ion beam After the portion, the ion current within the ion beam is measured before the significant portion of the ion beam becomes neutral. The system of claim 2, wherein the last energy level of the ion beam corresponds to a deflection angle of about 15 degrees from the original path. The system of claim 1, wherein the AEF dose cup is tethered in an overscan area associated with the area of the workpiece scanned by the strip of ion beam. The system of claim 1 wherein the plane of the last energy bend within the ion beam is orthogonal to the plane of the strip of ion beam. The system of claim 1, wherein the AEF dose cup is located in the AEF system in an AEF chamber region, wherein a pump reduces pressure to below the end of the AEF chamber. Station pressure. The system of claim 1, further comprising a dose compensation control system wherein the AEF dose cup measurement is utilized to control the scanning speed of the workpiece across the ion beam. The system of claim 7, further comprising a pressure compensation process for correcting the AEF dose cup measurement result, the pressure compensation process comprising: a pressure sensor operable to measure an associated position The pressure of the implant system of the AFF system outside the end station, the sensor having an output coupled to the compensation control system to correct the scan speed based on the measured pressure; a compensation circuit and a compensation software routine One of the programs, the Adapting to determine a pressure compensation factor as a function of the measured pressure and the measured ion beam current; and a scanning movement control system operable to control the workpiece across the measured pressure and pressure compensation factor The scanning speed of the ion beam. The system of claim 8, wherein the AEF system is located in an area of the AEF chamber outside the end station chamber, and wherein the pressure in the AEF chamber is further reduced from a pump to below The pressure downstream of the station chamber at the end of the AEF chamber further reduces the effects of gas release and pressure on the AEF cup. The system of claim 1, wherein the reading from a dose cup adjacent to the workpiece is compared to the reading of the AEF cup during implantation to infer a difference in charge exchange rate between the two locations, This provides a decision on the number of neutral particles produced over the corresponding path length. The system of claim 1, wherein the ion current measured at the AEF dose cup is proportional to the flow of ions to the workpiece. The system of claim 1, wherein the ion current implanted in the workpiece is determined to be proportional to the ion current measured at the AEF dose cup according to a proportional factor C _P according to the following relationship: I _implanted = I _AEF * C _P . The system of claim 12, wherein the C _P is calculated based on the readings of the AEF cup and an end station cup to determine the charge exchange ratio affecting the AEF cup, and compensate for the change in pressure. . The system of claim 1, wherein the strip-type ion beam is a scanned ion beam. The system of claim 1, wherein the strip-type ion beam is a continuous ion beam. The system of claim 1, wherein the AEF dose cup measures the last energy associated with the ion beam at a position before the ion beam travels a greater portion of the ion beam path toward the workpiece. The ion current. The system of claim 16 wherein the AEF dose cup is positioned closer to the last energy bend of the ion beam than the workpiece. The system of claim 1, wherein the AEF dose cup is positioned closer to the last energy bend of the ion beam than the workpiece. The system of claim 16 wherein the AEF dose cup is associated with the ion prior to the subsequent exchange of ions of the ion beam over a path toward the workpiece. The ion current of the last energy of the beam measures the location of the job. The system of claim 1, wherein the AEF dose cup is associated with the ion beam prior to the ion beam having subsequently exchanged a significant portion of the ion beam on a path toward the workpiece. The ion flow of the last energy is measured at the location of the job. An ion implantation system comprising: an ion implanter configured to generate one of a scanned or striped ion beam; configured to bend the ion at a final energy bend An AEF system for filtering the energy of the ion beam; an AEF dose cup associated with the AEF system configured to measure ion beam current, the AEF dose cup being after the last energy bend, compared to a workpiece being closer to the last energy bend; and an end station downstream of the AEF system, the end station being defined by a chamber, wherein a workpiece is fixed in position to provide movement relative to the strip ion beam, Ions are implanted therein; wherein the AEF dose cup is external to the chamber of the end station. The system of claim 21, wherein the AEF system comprises: a pair of deflecting plates for deflecting the ion beam by a target deflection angle, thereby defining a correspondence from an original path The final energy level of the ion beam at a biased angle; a set of pressed electrodes downstream of the deflecting plates, the pressed electrodes being configured to terminate a positive potential imparted to the ion beam by the deflecting plates And the AEF dose cup is immediately after the last energy bend in the ion beam, and the ion current within the ion beam is measured before the significant portion of the ion beam becomes neutral. The system of claim 22, wherein the last energy level of the ion beam corresponds to a deflection angle of about 15 degrees from the original path. The system of claim 21, wherein the AEF dose cup is stalked by the strip ion beam associated with the workpiece. Within the overscan area of the area. The system of claim 21, wherein the plane of the last energy bend within the ion beam is orthogonal to the plane of the strip of ion beam. The system of claim 21, wherein the AEF dose cup is located in an AEF system upstream of the chamber region of the end station, wherein a pump reduces pressure to a pressure lower than the end station. The system of claim 21, further comprising a dose compensation control system wherein the AEF dose cup measurement is utilized to control the scanning speed of the workpiece across the ion beam. The system of claim 27, further comprising a pressure compensation process for correcting the AEF dose cup measurement result, the pressure compensation process comprising: a pressure sensor operable to measure an associated position in the The pressure of the implant system of the AEF system outside the end station, the sensor having an output coupled to the compensation control system to correct the scan speed based on the measured pressure; a compensation circuit and a compensation software routine One of the programs adapted to determine a pressure compensation factor as a function of the measured pressure and the measured ion beam current; and a scanning movement control system operable to determine the pressure and A pressure compensation factor is used to control the scanning speed of the workpiece across the ion beam. The system of claim 27, wherein the AEF system is located in an AEF chamber region outside the end station chamber, and wherein The pressure in the AEF chamber is further reduced from a pump to a pressure lower than the end station downstream of the AEF chamber to further reduce the effects of gas release and pressure on the AEF cup. The system of claim 21, wherein the reading from the dose cup close to the workpiece is compared with the reading of the AEF cup during implantation to infer the difference in charge exchange rate between the two locations, This provides a determination of the number of neutral particles produced over the corresponding path length. The system of claim 21, wherein the ion current measured at the AEF dose cup is proportional to the flow of ions to the workpiece. The system of claim 21, wherein the ion flow implanted in the workpiece is determined to be proportional to the following relationship during the implantation according to a proportional factor C _P proportional to the measured at the AEF dose cup Ion flow: I _implanted = I _AEF * C _P . The system of claim 32, wherein the C _P is calculated based on readings of the AEF cup and an end station cup to determine a charge exchange ratio affecting the AEF cup, and compensating for the pressure change reading. The system of claim 21, wherein the ion beam is a scanned ion beam. The system of claim 21, wherein the ion beam is a continuous strip of ion beam. The system of claim 21, wherein the AEF dose cup is associated with the ion prior to the subsequent exchange of a larger portion of the ion beam on the path toward the workpiece. The ion current of the last energy of the beam measures the position of the job. The system of claim 21, wherein the AEF dose cup is associated with the ion beam before it is subsequently exchanged for a significant portion of the ion beam on the path toward the workpiece. The ion flow of the last energy measures the position of the job. A method of dynamically compensating for pressure and ion source variation using an AEF dose cup located near a last energy bend upstream of an end station, the AEF dose cup being external to an end station chamber of an ion implantation system, the method The method comprises: providing a workpiece in the end station, and having a profiled cup at a workpiece plane near the ion implantation system; correcting the AEF dose cup during an implant setting to be relative to the distribution The contour cup establishes an ion flow proportionality constant; an initial scan speed of the workpiece passing through the ion beam; using the ion implantation system and the established ion flow proportionality constant, implanting an ion beam to a workpiece in a region while Measuring the ion beam current at the AEF dose cup in the ion implantation system; measuring the ion current associated with the implanted workpiece; and measuring the ion beam current at the AEF dose cup based on the initial scan speed, the ion flow proportionality The constant and a desired dose level determine a scan speed compensation.