JPH06103956A - Ion implantation device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a state that ion implantation is processed based on the scanning voltage of abnormal wave forms which does not meet an implantation condition. CONSTITUTION:A wave form generator 5 allows a scanning power supply 4 to generate a scanning voltage wave form signal (b) which generates scanning voltage meeting to an implantation condition, in response to a wave designation signal 9 outputted by a controller 7. The aforesaid scanning voltage wave form signal (b) is taken in the controller 7 via an A/D converter circuit 6. Scanning voltage wave form signal (b) is stored in the memory 7a of the controller 7 in advance, the controller 7 compares data from the A/D converter circuit 6 with scanning voltage wave form data within the memory 7a, and when the errors of both data are found to have been out of a specified range, the controller instantly suspends implantation ion.

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 uniformly implanting impurity ions into an object to be ion-irradiated such as a wafer. The present invention relates to an electrostatic scanning type ion implantation apparatus.

[0002]

2. Description of the Related Art An ion implanter, in which ions are generated in a vacuum, is extracted as an ion beam, and the desired ion beam is selectively extracted by mass spectrometry using a magnetic field. By irradiating an ion irradiation target such as a wafer by accelerating to a predetermined energy, impurities are injected into the ion irradiation target. The ability to inject into the depth with good controllability makes it an important device in the manufacture of current integrated circuits.

The above-mentioned ion implantation apparatus electrostatically scans a spot-shaped ion beam with a high frequency voltage in the X direction (eg, horizontal direction) and in the Y direction (eg, vertical direction) orthogonal to the X direction. As shown in FIG. 3, an X scan electrode 51 for scanning the ion beam in the X direction is available.
A high frequency scanning voltage having a triangular waveform is applied from the X scanning power source 53 and the Y scanning power source 54 to the Y scanning electrodes 52 and 52 for scanning 51 and the ion beam in the Y direction, respectively.

Usually, the ion implantation angle (inclination of the ion irradiation surface of the wafer with respect to the optical axis of the ions) to the wafer during ion implantation is set to about 7 ° in order to prevent the channeling phenomenon. As described above, when the ion implantation angle is relatively small, even if the scanning voltage waveform is a triangular wave, the implantation uniformity within the wafer surface is not significantly affected.

By the way, in recent years, in order to cope with a VLSI memory or the like which constitutes a capacitor by implanting ions into the side surface of a trench (groove) on the surface of a wafer, and to cope with an increase in the diameter of a wafer used, a larger ion implantation is carried out. Since it becomes necessary to perform ion implantation at an angle, an ion implantation apparatus having a variable implantation angle function capable of adjusting the ion implantation angle according to the wafer used has come to be used. However, when the ion implantation angle is increased, the projection area of the beam on the wafer surface becomes non-uniform with the ion beam scanned by the triangular wave scanning voltage, and the implantation uniformity deteriorates. This tendency becomes more remarkable as the wafer size increases.

Therefore, in the ion implantation apparatus having the above-mentioned variable implantation angle function, in order to improve the nonuniformity of the implantation, the triangular wave which is a normal scanning voltage waveform is distorted to electrostatically ionize the ion beam on the wafer surface. It is necessary to correct the scanning speed. Therefore, in the above-described ion implantation apparatus, the waveform of the scanning voltage applied to the scanning electrodes is not limited to the triangular wave, and a plurality of waveforms are used according to the implantation conditions (size of wafer used, ion implantation angle, etc.). ing.

Therefore, in the above-mentioned ion implantation apparatus, the waveform generator 55 in which a plurality of scanning voltage waveform data corresponding to the implantation conditions are stored in advance generates the analog scanning voltage waveform signal d corresponding to the implantation conditions. It has become. The operation of the waveform generator 55 is controlled by the controller 56, and the waveform generator 55 generates the designated scanning voltage waveform signal d based on the waveform designation signal c output from the controller 56. X scanning power source 5
3 and Y scanning power supply 54.
Thereby, the X scanning power source 53 and the Y scanning power source 54
Applies a scanning voltage according to the scanning voltage waveform signal d to the X scanning electrodes 51, 51 and the Y scanning electrodes 52, 52. The X scanning electrodes 51, 51 and the Y scanning electrodes 52, 52. The ion beam scanned at 52 passes through an irradiation mask (not shown) and is then irradiated onto the wafer.

As described above, the scanning voltage having the waveform corresponding to the injection condition is applied to the X scan electrodes 51, 51 and the Y scan electrodes 52.5.
By applying a voltage of 2 to scan the ion beam, excellent implantation uniformity can be obtained.

[0009]

By the way, from the past,
Before setting the wafer at the implantation position and performing the actual ion implantation process, a measurement system (flag) is provided at the implantation position equivalent to the wafer setting position to measure the beam current of the ion beam that has passed through the irradiation mask. Thus, the beam scanning state is confirmed. However, only by measuring the beam current at the implantation position, it is not possible to determine what waveform of the scanning voltage is used to scan the ion beam.

Therefore, in the conventional ion implantation apparatus, for example, a voltage waveform switching abnormality such as the output of a signal other than the specified scanning voltage waveform signal due to a failure of the signal switching circuit of the waveform generator 55 occurs, or Alternatively, even if an abnormality of the scanning voltage waveform signal itself occurs, it cannot be detected, so that the ion implantation process is performed by the ion beam scanned by the scanning voltage of the waveform that does not correspond to the implantation conditions. There is a problem that it includes such a risk.

The present invention has been made in view of the above, and an object thereof is to monitor a scanning voltage waveform signal output from a waveform generating means (waveform generator) to detect an abnormal waveform that does not correspond to an injection condition. It is an object of the present invention to provide an ion implantation apparatus capable of avoiding a situation in which an ion implantation process is performed by an ion beam scanned by a scanning voltage.

[0012]

In order to solve the above-mentioned problems, an ion implantation apparatus of the present invention comprises a scanning electrode for scanning an ion beam, a scanning power supply for applying a scanning voltage to the scanning electrode, Waveform generating means for generating a scanning voltage waveform signal for generating a scanning voltage having a waveform according to the injection conditions in the scanning power source, and irradiating the ion irradiation target with an ion beam electrostatically scanned by the scanning electrodes. Then, the impurity ions are uniformly implanted, and the following features are taken.

That is, the ion implantation apparatus has a storage means for storing the scanning voltage waveform data corresponding to the scanning voltage waveform signal, takes in the scanning voltage waveform signal generated by the waveform generating means, and stores the scanning voltage waveform signal. There is provided scanning voltage waveform abnormality detection means for comparing the scanning voltage waveform data stored in the storage means and determining whether or not there is an abnormality in the scanning voltage waveform signal.

[0014]

According to the above construction, the scanning voltage waveform signal corresponding to the injection condition is output from the waveform generating means to the scanning power supply, so that the scanning voltage having the waveform corresponding to the scanning voltage waveform signal is output from the scanning power supply. As a result of being applied to the scanning electrodes, the ion beam is electrostatically scanned to irradiate the surface of the ion irradiation target.

The scanning voltage waveform signal output from the waveform generating means is for generating a scanning voltage having an optimum waveform according to the implantation conditions such as the size of the ion irradiation target and the ion implantation angle. The scanning voltage waveform data corresponding to the waveform signal is stored in advance in the storage unit of the scanning voltage waveform abnormality detection unit.

The scanning voltage waveform signal output from the waveform generating means is input to the scanning power supply and taken in by the scanning voltage waveform abnormality detecting means. The scanning voltage waveform abnormality detecting means compares the read scanning voltage waveform signal with the scanning voltage waveform data stored in the storage means to detect an abnormality in the scanning voltage waveform signal.

Therefore, when the scanning voltage waveform abnormality detecting means detects an abnormality in the scanning voltage waveform signal, if the apparatus is configured to be interlocked, the ion implantation process is performed with a scanning voltage having a waveform that does not correspond to the implantation conditions. It is possible to prevent such a situation that is done.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS. 1 and 2.

The ion implantation apparatus according to the present embodiment is an electrostatic scanning system in which an ion beam is electrostatically scanned with a high frequency voltage in the X direction (eg horizontal direction) and the Y direction (eg vertical direction) orthogonal to the X direction. belongs to.

As shown in FIG. 2, the above-mentioned ion implantation apparatus includes a pair of X scanning electrodes 1 and 1 as scanning electrodes for scanning a spot-like ion beam in the X direction and a scanning electrode for scanning the ion beam in the Y direction. Has a pair of Y scanning electrodes 2.2.

An irradiation mask 8 having an opening 8a having a predetermined area is provided on the downstream side of the X scanning electrode 1.1 in the beam traveling direction, and further on the downstream side of the irradiation mask 8, an ion irradiation object is provided. A wafer holding member 10 for holding the wafer 9 is provided.

The wafer holding member 10 is supported by a support shaft 10a, and the support shaft 10a is used as a rotation shaft.
It is adapted to be rotationally driven in a B direction in the figure by a drive motor (not shown). Further, the wafer holding member 10
Is rotatable in the direction of arrow A in the figure, and the ion implantation angle θ to the wafer 9 is variable within a predetermined range (for example, 0 ° to 60 °).

As shown in FIG. 1, high-frequency scanning voltages 180 ° out of phase with each other are applied from the X-scanning power source 3 to the pair of X-scanning electrodes 1.1, and the pair of Y-scanning electrodes 1 and
High frequency scanning voltages 180 ° out of phase with each other are applied from the Y scanning power source 4 to the scanning electrodes 2 and 2. A scanning voltage waveform signal b generated by a waveform generator (waveform generating means) 5 is input to the X scanning power source 3 and the Y scanning power source 4, and the X scanning power source 3 and the Y scanning power source 4 are input. Is a scanning voltage based on the scanning voltage waveform signal b.
・ Apply to 2 respectively.

The waveform generator 5 has a built-in storage device (not shown), and the storage device has a plurality of scanning voltage waveforms according to the implantation conditions (size of the wafer 9 used, ion implantation angle θ, etc.). The data is stored in advance. Then, the waveform generator 5 converts the scanning voltage waveform data into an analog amount by a D / A conversion circuit (not shown) and outputs it as a scanning voltage waveform signal b.

The scanning voltage waveform data is obtained by calculating a basic waveform in which a triangular wave is distorted based on the ion implantation angle θ, the size of the wafer 9 and the like, and an actual ion implantation treatment experiment is performed using the scanning voltage of this basic waveform. It was obtained by performing repeated waveform correction from the result of the wafer in-plane implantation uniformity obtained by this experiment, and is the optimum data according to the implantation conditions.

The operation of the waveform generator 5 is controlled by a controller (scanning voltage waveform abnormality detecting means) 7. When the ion implantation process is performed, the controller 7 sends a waveform designation signal to It outputs to the waveform generator 5 and generates the scanning voltage waveform signal b according to the injection condition. The controller 7 has a memory (storage means) 7a, and the memory 7a has a plurality of scanning voltage waveform data stored in the waveform generator 5 and the same data (output from the waveform generator 5). Scanning voltage waveform data corresponding to the scanning voltage waveform signal b) is stored.

Further, the scanning voltage waveform signal b generated by the waveform generator 5 in response to the waveform designation signal a from the controller 7 is converted into a digital amount by the A / D conversion circuit 6 and taken into the controller 7. It is like this.
The controller 7 then outputs the data generated by the waveform generator 5 and converted into a digital amount by the A / D conversion circuit 6 and the scanning voltage waveform data (to the waveform generator 5) stored in the memory 7a. The output waveform designating signal a and the corresponding one) are compared with each other to check whether or not the error between the two data is within a predetermined range.

Further, the ion implantation apparatus has a measurement system (flag) (not shown) for measuring the beam current of the ion beam passing through the irradiation mask 8 at the implantation position equivalent to the set position of the wafer 9. The scanning state of the ion beam can be confirmed.

The ion implantation operation of the above-mentioned ion implantation apparatus having the above structure will be described below.

By inputting data such as the size of the wafer 9 to be used and the ion implantation angle θ from an input device (not shown), the controller 7 instructs the waveform generator 5 to specify a waveform according to the implantation conditions. The signal a will be output. As a result, the waveform generator 5 outputs the analog scanning voltage waveform signal b corresponding to the input waveform designation signal a to the X scanning power source 3 and the Y scanning power source 4. Then, the X scanning power source 3 and the Y scanning power source 4
Applies a scan voltage corresponding to the scan voltage waveform signal b output from the waveform generator 5 to the X scan electrode 1.1 and the Y scan electrode 2.2, respectively.

Thus, after being extracted from the ion source (not shown) into a high vacuum, only predetermined ions are selected by the mass spectrometer (not shown), and further predetermined by the acceleration tube (not shown). The spot-like ion beam accelerated to the energy is scanned by passing between the pair of X scan electrodes 1 and 1 and between the pair of Y scan electrodes 2 and 2 and passes through the opening 8 a of the irradiation mask 8. Then, the rotating wafer 9 held by the wafer holding member 10 is irradiated.

Further, the scanning voltage waveform signal b output from the waveform generator 5 is converted into a digital amount by the A / D conversion circuit 6 and taken into the controller 7. Then, the controller 7 compares the data from the A / D conversion circuit 6 with the scanning voltage waveform data in the memory 7a corresponding to the waveform designation signal a output to the waveform generator 5,
When the error between the two data is out of the predetermined range, the ion implantation process is stopped, and an alarm operation (abnormality display, generation of alarm sound, etc.) indicating an abnormal scanning voltage waveform is performed on a display (not shown) or the like.

As described above, in the present ion implantation apparatus, the scanning voltage waveform signal b output from the waveform generator 5 is constantly monitored by the controller 7. Therefore, for example, signal switching in the waveform generator 5 is performed. A voltage waveform switching abnormality such as the output of a signal other than the scanning voltage waveform signal designated by the waveform designation signal a due to a circuit (not shown) failure, or an abnormality in the scanning voltage waveform signal b itself occurs Even if it does, the abnormality can be detected immediately. Therefore, by interlocking the device when an abnormality is detected, it is possible to prevent the ion implantation process from being performed by the scanning voltage having an abnormal waveform that does not correspond to the implantation conditions.

The types of the scanning voltage waveform signal b generated by the waveform generator 5 are as many as the number of ion implantation conditions, and of course, only one type may be used.

[0035]

As described above, the ion implantation apparatus of the present invention has a scanning electrode for scanning an ion beam, a scanning power source for applying a scanning voltage to the scanning electrode, and an implantation condition for the scanning power source. With a waveform generating means for generating a scanning voltage waveform signal for generating a scanning voltage having a different waveform,
Further, the scanning voltage waveform data corresponding to the scanning voltage waveform signal is stored in the storage means, and the scanning voltage waveform signal generated by the waveform generating means is taken in to store the scanning voltage waveform stored in the storage means. The scanning voltage waveform abnormality detecting means is provided for comparing the data with the data and determining whether or not there is an abnormality in the scanning voltage waveform signal.

Therefore, if an abnormality occurs in the scanning voltage waveform signal output from the waveform generating means, the abnormality is immediately detected by the scanning voltage waveform abnormality detecting means that constantly monitors the scanning voltage waveform signal. If the device is configured to be interlocked when an abnormality is detected, it is possible to avoid a situation in which the ion implantation process is performed by a scanning voltage having an abnormal waveform that does not correspond to the implantation conditions.

[Brief description of drawings]

1 is a block diagram showing an embodiment of the present invention and showing a configuration of a main part of a beam scanning system in an ion implantation apparatus.

FIG. 2 is an explanatory diagram showing a state in which an ion beam scanned by the beam scanning system is applied to a wafer.

FIG. 3 is a block diagram showing a conventional example and showing a configuration of a main part of a beam scanning system in an ion implantation apparatus.

[Explanation of symbols]

 1 X scan electrode (scan electrode) 2 Y scan electrode (scan electrode) 3 X scan power source (scan power source) 4 Y scan power source (scan power source) 5 Waveform generator (waveform generating means) 6 A / D conversion circuit 7 Controller ( Scanning voltage waveform abnormality detection means) 7a Memory (storage means) 9 Wafer (ion irradiation target object)

Claims (1)

[Claims] 1. A scan electrode for scanning an ion beam, a scan power supply for applying a scan voltage to the scan electrode, and a scan voltage waveform signal for generating a scan voltage having a waveform according to an injection condition in the scan power supply. An ion implantation apparatus for irradiating an ion-irradiated object with an ion beam electrostatically scanned by the scanning electrodes to uniformly implant impurity ions, which corresponds to the scanning voltage waveform signal. Scanning voltage waveform data is stored in the storage means, and the scanning voltage waveform signal generated by the waveform generating means is fetched and compared with the scanning voltage waveform data stored in the storage means. An ion implantation apparatus comprising a scanning voltage waveform abnormality detection means for determining the presence / absence of abnormalities.