JPH09320507A - Ion implantation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion implantation device which allows evaluating the uniformity of implanted ions when the ions are implanted as a semiconductor or a substrate equipped with the semiconductor is rotated within the range of a planar ion beam. SOLUTION: The in-plane intensity distribution of a planar ion beam emitted from an ion source with the intersection points of X- and Y-axes as the centers of rotation of a substrate is measured on the X-Y plane, and from the measurements obtained, the average value of the measurements located at points at equal distances from the intersections is calculated; values obtained through the averaging are handled as the intensities of the ion beam at the points at equal distances, and the distribution of the ion beam which takes the rotation of the substrate into account is calculated for evaluation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus for implanting ions into a semiconductor, and more specifically, implantation for implanting ions while rotating a semiconductor or a substrate provided with a semiconductor within a range of a planar ion beam. It relates to the evaluation of ion uniformity.

[0002]

2. Description of the Related Art For example, in the production of a TFT active matrix type liquid crystal display in which a transistor array is formed of a semiconductor thin film on a glass substrate, the source / drain regions of the transistors are formed by an ion implantation device. . An ion implantation apparatus for forming such a transistor or the like is configured by attaching an ion source 1 to an ion implantation processing chamber 2 as shown in a schematic configuration diagram of an example in FIG.

The ion source 1 comprises a plasma generating chamber 11 and an accelerating chamber 12 for accelerating ions from the generated plasma. The plasma generating chamber 11 is closed by disposing an electrode 14 on the rear surface thereof via an insulator 13. The front surface is covered with the first mesh-shaped electrode 15. The rear of the acceleration chamber 12 is first.
The mesh-shaped electrode 15 and the fourth mesh-shaped electrode 18 are arranged on the front surface, and the second mesh-shaped electrode 16 is arranged on the first electrode 15 side and the third mesh-shaped electrode 18 is arranged on the fourth electrode 18 side. The electrode 17 is arranged.

The ion source 1 of this example is a high-frequency ion source, and the voltage of the high-frequency power source 19 is applied between the electrode 14 and the side wall 33 of the plasma generation chamber 11 and between the first electrode 15 through the matching circuit 20. The plasma generating chamber 11 is configured to generate high frequency discharge. Further, an acceleration power supply 21 is provided between the first electrode 15 and the fourth electrode 18, and an ion extraction power supply 2 is provided between the first electrode 15 and the second electrode 16.
2, the voltage of the backflow electron suppressing power supply 23 is applied between the third electrode 17 and the fourth electrode 18, respectively.
Electrode 18 is grounded.

A nozzle 24 for introducing a raw material gas, for example, a gas obtained by diluting PH3 (phosphine) with H2 (hydrogen) from a raw material gas source 25, 26 is arranged in the vicinity of the fourth electrode 18. The introduced raw material gas passes through each electrode and is introduced into the plasma generation chamber 11, where it is turned into plasma by high-frequency discharge, and is ion-implanted as an ion beam from the mesh holes of the fourth electrode 18 by the electric field action of each electrode. It is emitted into the processing chamber 2.

A fourth electrode 1 is provided in the ion implantation processing chamber 2.
No. 8 surface, that is, a holder 28 for holding the substrate 27 on which the ions are implanted facing the exit surface of the planar ion beam.
Is rotatably provided, and is rotated when ion-implanting the substrate 27.

Reference numeral 29 is a measuring means for measuring the in-plane intensity distribution of the planar ion beam emitted from the ion source 1, by moving one Faraday cup for measuring the ion beam in a straight line or at the center of the substrate. There is also measuring means for measuring the one-dimensional ion beam intensity distribution by moving (or rotating) along an arc passing through, but in this example, the Faraday cups 30 are arranged linearly as shown in FIG. The Faraday cup array is moved in the direction perpendicular to the array on the front surface of the substrate 27 to measure the ion beam intensity at each point in the plane. In addition, 32 is an evaluation arithmetic unit, 31 is a monitor and the like.

[0008]

By the way, conventionally, based on the measured values at each position in the plane of the planar ion beam measured by such measuring means, variations in the intensity distribution in the plane of the planar ion beam, That is, the ion beam is evaluated and managed by calculating the standard deviation. However, this evaluation does not include the rotating element of the substrate at the time of ion implantation, so it is not possible to evaluate the variation of the implanted ions with respect to the substrate, and it is possible to more accurately evaluate the variation of the implanted ions with respect to the substrate. Development of the device is desired.

The present invention has been made in view of the above circumstances, and is for evaluating the uniformity of implanted ions when implanting ions while rotating a semiconductor or a substrate provided with a semiconductor within the range of a planar ion beam. An object of the present invention is to provide an ion implantation device that can be used.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an ion source for emitting a planar ion beam, and a substrate which is arranged so as to face the plane ion beam emitting surface of the ion source and into which ions are implanted. A rotatable holder that holds the ion beam intensity at an equidistant position with respect to the center of rotation of the holder, and an evaluation calculation device that makes the value obtained by the averaging the ion beam intensity at the equidistant position; It is achieved by providing an ion implantation device characterized by comprising:

Another object of the present invention is to rotate an ion source that emits a planar ion beam and a substrate that is arranged to face the emission surface of the planar ion beam of the ion source and that is to be implanted with ions. Holder, measurement means arranged between the ion source and the holder for measuring the in-plane intensity distribution of the planar ion beam emitted from the ion source at settable constant intervals, and the measurement means. Among the measurement values measured in, the measurement values measured at the equidistant position with respect to the rotation center of the holder are averaged, and the value obtained by the averaging is the measurement value measured at the equidistant position. It is achieved by providing an ion implantation device characterized by comprising an evaluation calculation device for

According to the above feature of the present invention, with respect to the planar ion beam emitted from the ion source, the ions at each point on the surface equidistant from the rotation center of the holder, that is, the rotation center of the substrate. The beam intensities are averaged, and the average value is treated as the ion beam intensities at the respective points at the equidistant positions, whereby the variation in the in-plane intensity distribution of the planar ion beam is evaluated. Therefore, the evaluation includes the rotating element of the substrate, and it is possible to evaluate and control the variation of the implanted ions in accordance with the actual evaluation. Further, when the planar ion beam has a strong in-plane asymmetry, it is possible to evaluate the homogeneity closer to the actual one.

In addition, the measuring means for measuring the in-plane intensity distribution of the planar ion beam emitted from the ion source at fixed intervals allows the ion beam intensity at each point on the surface to be set at an appropriately set interval. When the measurement is performed, the number of measurement points is determined according to the size of the substrate, etc., and thus the calculation speed for evaluation can be increased.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an example of an ion implantation apparatus according to the present invention will be described with reference to the drawings. Since this example of the ion implantation apparatus according to the present invention includes the same ion implantation processing chamber 2 and ion source 1 as the ion implantation apparatus described with reference to FIG. Detailed description is omitted.

The measuring means 29 for measuring the intensity distribution of the planar ion beam emitted from the mesh hole of the fourth electrode 18 of the ion source 1 has the same structure as the measuring means described with reference to FIG. However, in this example of the ion implantation apparatus according to the present invention, a Faraday cup array in which the Faraday cups 30 are arranged in a straight line (in the Y-axis direction) at equal intervals traverses the entire surface of the substrate 27 on the front surface of the substrate 27. The Faraday cup 30 is moved (scanned in the X-axis direction), that is, scanned, and the intensity of the ion beam is measured by each Faraday cup at each position at the same intervals as the Faraday cup 30.

The measurement value measured by each Faraday cup is sent to the evaluation calculation device 32, and the evaluation value is calculated by the evaluation calculation device 32. In this example of the ion implantation apparatus according to the present invention, the evaluation arithmetic unit 32 is different from the conventional one, and the evaluation value in consideration of the rotation of the substrate 27 is calculated.

By the way, when the rotation of the substrate 27 is taken into consideration, the calculation by the evaluation arithmetic unit 32 of the ion implantation apparatus according to the present invention is a portion located on the circumference of the same radius with the center of rotation of the substrate 27 as the center. Even if the intensity of the ion beam varies, the irradiation amount of the ion beam of the substrate 27 located on the circumference is averaged because the substrate 27 is rotating. The distribution g (r) (r is a radius centered on the rotation center of the substrate 27)
The distribution in the radial direction is obtained by calculating the formula 1 for each intensity fi (r, θ) (θ is a rotation angle) from the mesh hole of the fourth electrode 18, ie, the ion beam extraction hole.

[0018]

[Equation 1]

However, the substrate has 370.times.470 mm or 40 mm, as seen, for example, in liquid crystal displays.
There is a large size of 0 × 500 mm, and in this case, there are about 5000 ion beam extraction holes in the ion source 1, and the number of ion beam extraction holes is further increased for a larger substrate. It takes too much calculation time to calculate the formula 1 for these holes.

Therefore, in this example, the Faraday cup array in which the in-plane ion beam intensity distribution is arranged at equal intervals in the Y-axis direction is scanned at equal intervals in the X-axis direction and measured on the XY plane at regular intervals. Then, the finite number of measured values is used to evaluate the distribution in the ion beam plane.
Regarding the data of each evaluated point, the values of points equidistant from the rotation center of the substrate 27 are averaged, and the averaged value is treated as the value of each point. When the distribution is evaluated at equal intervals in both the X-axis and Y-axis directions, the intensity at each point can be treated by the equation (2).

[0021]

[Equation 2]

That is, as can be understood from FIG. 1, with the intersection of the X axis and the Y axis as the center of rotation, the value of the point at that intersection is used as it is (n = 1), and on the X and Y axes, There are 4 points (n = 4) that are equally spaced from the intersection (n = 4), and there are 4 points (n = 4) that are equally spaced from the intersection on the X1 axis and Y1 axis that are rotated by 45 degrees on the X and Y axes. The average value of 4 points is set as the value of 4 points, and the other points have 8 points at equal intervals. Similarly, the value averaged by 8 points is set as the value of 8 points.

FIG. 5 shows the ion beam distribution (normalized to the maximum value) based on the data averaged for each point in this way.
In addition, Fig. 4 shows the ion beam distribution (normalized by the maximum value) based on the measurement values measured at equal intervals, and at the same interval as the result of obtaining the standard deviation (variation) from the data averaged for each point. Table 1 shows the result of obtaining the standard deviation from the measured values. The standard deviation is calculated using the standard σ
This is a calculation formula.

[0024]

[Table 1]

As is clear from FIGS. 4 and 5, the ion beam distribution obtained by averaging data, that is, the data taking into account the rotation, has good symmetry with respect to the ion beam distribution obtained by the measurement values measured at equal intervals. It is distributed.
Regarding the distribution of the actual implanted ions, it is understood that the distribution of the sheet resistance of the silicon wafer is 3 to 10% with good symmetry, and the distribution based on the averaged data actually conforms.

FIG. 6 is a diagram showing the distribution of the ion beam when the ion beam extracted from the ion beam extraction hole has a strong convergence. In this case, the in-plane distribution of the ion beam becomes extremely strong and weak. It is in very poor uniformity. When the averaging operation is used for such a distribution, the uniformity of the ion beam based on the original measurement value is 10 to 15 when the 3σ value shows 30 to 40%.
% Is expected. Even in such a case, the sheet resistance uniformity of the silicon wafer is 10% or less, and it is understood that the distribution based on the averaged data actually conforms.

FIG. 7 shows a distribution calculation result in the case of using averaged data for the current intensity.

[0028]

As described above, according to the present invention, with respect to the planar ion beam emitted from the ion source, the ion beam intensity at each point on the surface equidistant to the rotation center of the substrate is determined. The average value is treated as the ion beam intensity at each point at the equidistant position, and the variation of the in-plane intensity distribution of the planar ion beam can be evaluated. Is included, the ion implantation distribution of the substrate can be monitored in a state close to the actual distribution, and highly reliable quality control can be performed.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an evaluation calculation of an example of an ion implantation apparatus according to the present invention.

FIG. 2 is a schematic configuration diagram of an ion implantation device.

FIG. 3 is a schematic configuration diagram of a measurement unit that measures the in-plane intensity distribution of the planar ion beam of the ion implantation apparatus shown in FIG.

FIG. 4 is a distribution diagram of ion beams based on measured values.

FIG. 5 is a distribution diagram of an ion beam evaluated by the present invention.

FIG. 6 is another distribution diagram of ion beams according to measured values.

FIG. 7 is a distribution calculation result diagram with respect to the current intensity by the evaluation according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ion source 2 Ion implantation processing chamber 11 Plasma generation chamber 12 Acceleration chamber 14, 15, 16, 17, 18 Electrode 19 High frequency power supply 24 Nozzle 27 Substrate 28 Holder 29 Faraday cup array (measuring means) 32 Evaluation and operation device

[Procedure amendment]

[Submission date] June 6, 1996

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

[Fig. 2]

Claims (2)

[Claims] 1. An ion source for emitting a planar ion beam, a rotatable holder for holding a substrate on which ions are implanted, the substrate being arranged so as to face the emission surface of the planar ion beam of the ion source, and the holder. Ion beam intensities at equidistant positions with respect to the center of rotation of the ion beam, and an evaluation calculation device that uses the averaged value as the ion beam intensity at the equidistant positions. Injection device. 2. An ion source for emitting a planar ion beam, a rotatable holder for holding a substrate on which ions are implanted, the substrate being arranged so as to face the emission surface of the planar ion beam of the ion source, and the ion. Measuring means arranged between the ion source and the holder to measure the in-plane intensity distribution of the planar ion beam emitted from the ion source at fixed intervals, and the measurement values measured by the measuring means. Among these, an evaluation calculation device that averages the measurement values measured at the equidistant position with respect to the rotation center of the holder, and sets the value obtained by the averaging as the measurement value measured at the equidistant position. An ion implanter characterized by being provided.