JPS61230252A - Ion implantation device - Google Patents

Abstract

PURPOSE:To improve the operation of an ion implantation device by performing controlling, setting and switching by installing two implantation chambers each containing an electron shower electrode and using a power supply having a filament current supply and an acceleration voltage supply. CONSTITUTION:An ion implantation device is constituted of two implantation chambers, two electron shower electrodes each of which is contained in one of the implantation chambers and a pair of power supplies for actuating electrodes. An electron shower power supply 100 is controlled by a control unit 200 including a computer to control the filaments 300 and 400 of the electron shower electrodes and their accelerating voltage. Input units 500 and 600 are used to set currents for the filaments 300 ad 400. Switching between the implantation chambers as well as the initiation and suspension of implantation are set by an input unit 700 and performed by the control unit 200. Due to the above structure, it is possible to facilitate the operation and increase the implantation efficiency of the device by achieving smooth setting and controlling.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ion implantation device having an electron shower that electrically neutralizes a charged wear surface.

[Background of the invention]

FIG. 4 shows a configuration diagram of the ion implanter.

In the figure, an ion beam 2 that has been turned into plasma and accelerated in an ion source 1 is subjected to selective separation of ions by a separation magnet 3, and only the selected ion beam 2 is deflected by a deflection magnet 4 to perform ion implantation. Sample 6 (implanted into silicon wafer 1-1) mounted in chamber 5 or ion implantation chamber 7.

The above explanation covers only the minimum necessary elements for explaining the present invention, such as the supply section for the gas to be turned into plasma, the power supply for ionization, the separation magnet, the power supply for the deflection magnet, etc. , the beam line of the ion beam 2 is evacuated, and the sample 6 is mounted on a disk that rotates and scans with respect to the beam 2. The details of the contents are omitted. Note that the electron shower electrode is located at 8° 9 of the ion beam 2 intake port of the implantation chambers 5 and 7.

Generally, when a high-current ion beam is implanted into the silicon wafer 6, the insulating film on the wafer surface is charged with ions, and it is known that depending on the pattern on the wafer, a part of the film may be damaged by electrostatic discharge. .

This K significantly reduces the yield of the product. One commonly known solution to this problem is an electron shower, which electrically neutralizes the ion beam and the charged wafer surface by emitting low-energy electrons toward the ion beam. .

FIG. 5 shows details of the ion implantation chamber 5, sample (silicon wafer) 6, and ion beam intake port 8 shown in FIG. The electron shower system will be explained using FIG. 5.

In the figure, a rotating disk 10 on which the Unino 6 is mounted is provided in the driving chamber 5, and this rotates at a constant speed. The ion beam 2 is implanted into a wafer 6, and when the ion beam 2 is implanted into the wafer 6, secondary electrons are generated. A suppressor electrode 11 is provided to repel the secondary electrons generated from the wafer 6. A negative voltage is applied to this suppressor electrode 11 . A seven-day cup 12 for accurately measuring the beam current is provided inside the suppressor electrode 11 and the rotating disk 10, and the electron shower 16 is attached to a part of this cup. A filament current is supplied to the filament 15 of the electron shower 16 from a filament power supply 17. Further, thermionic electrons from the filament 15 accelerated by the acceleration power source 18 are emitted forward, mix with the ion beam 2, and neutralize the ion beam 2. Therefore, the surface of Uni-No 6 will not be charged by ions. The ion current is measured by an ion ammeter 19. This describes one implantation chamber, but if there are two implantation chambers and the ion beam 2 is implanted alternately and without interruption, the filament power source 17
and an acceleration power source 18 separately, or a filament power source 17 is provided for each driving chamber, and one acceleration power source 18 is provided.
When implanting the ion beam 2 using the ion beam, the filament current and acceleration voltage must be adjusted each time two implantation chambers are selected, which has the disadvantage of extremely poor operability. Ta. Furthermore, if a large filament current is suddenly applied when switching the filament power supply, the life of the filament will be shortened due to rush current, so the current is gradually increased, resulting in poor working efficiency.

[Purpose of the invention]

An object of the present invention is to provide an ion implanter that is easy to operate and can improve work efficiency.

[Summary of the invention]

The present invention has two implantation chambers and individually installs electron shower electrodes, allows the filament current and accelerating voltage to be applied to the electron shower electrodes to be set separately, and continuously and rapidly. In order to switch to the filament current C, for example, an electron current of an electron shower of 100 mA, a filament current 17 that is set separately is provided with a means for reaching the set value with a certain time constant C (for example, 10 seconds), and two In the case of continuous implantation using a chamber, the electron shower electrode is switched in conjunction with the selection of the implantation chamber.

[Embodiments of the invention]

Examples of the present invention will be described below.

FIG. 1 shows a schematic system configuration diagram of an electron shower according to an embodiment of the present invention.

In the figure, an electron shower electric current 111f100 supplies current to filaments 300.degree. 400 connected to its output in response to a control signal from a control device 200, thereby emitting thermoelectrons. Note that the electron shower power supply 100 also includes an accelerating voltage power supply for extracting thermoelectrons. The control device 200 is connected to an input device 500 and an input device 600 for setting each filament current, and is also connected to an input device 700 for switching the driving chamber, starting and stopping driving, etc. Since the control device 200 is controlled by a computer, the flow of its operation (operation) is shown in FIG.

In FIG. 2, steps 201 and 202 are preparation settings for the electron shower power supply C (hereinafter referred to as E8 power supply) 100, and step 202 of AVTO/MAN switching (remote operation/switching of operation from the power supply panel) is performed by the control device. 2
00, but in this case, it is located at the E8 power supply 100. Steps 203 to 209 show a procedure for setting an emission current C (electronic current) drawn by applying a filament current and further applying an accelerating voltage. The interlock in step 203 is, for example, a signal indicating the degree of vacuum in the electron shower electrode section (this is because the filament will quickly burn out in the atmosphere).

Steps 204, 205, 206, 208, 209, etc. are switches of the input signal C panel of the input device 500, input device 600, and input device 700 shown in FIG.

The control device 200 receives the signal (which may be a signal from a potentiometer, etc., or may be an input from a keyboard, etc.), and the second
Turn on the EStS power supply 100 times according to the illustrated flow. Up to step 209, the emission current of each electron shower installed in the two implantation chambers is set in advance.

Next, steps 201 to 221 are steps for operating an electron shower in synchronization with the implantation of an ion beam into a wafer. Second figure illustrated steps 211, 213
, 218 is the input device 70 shown in FIG.
This is included in the 0 implantation start signal. Next, in step 214, before starting the driving, a ready switch is turned on (step 211), and the control device 200 is turned on.
Inside, the ion beam is first deflected according to the implantation chamber switching signal of the input device 700 shown in FIG. 1, the ES power supply 100 is turned on, and the ready signal is lit. After seeing the signal, turn on the start switch (step 213) to start typing. If an error occurs during the driving process, all the abnormal signals related to the driving process and the alarm signal from the ES power source are detected, the process repeats steps 215 to 219 and returns again. If no error has occurred, the entry is completed in step 20, the entry completion operation (step 221) is performed by the bank employee, and the process returns to step 214. Since the control device 200 remembers which one to execute and which one to drive, in step 214, if it is to start driving, it will roar,
The following steps are executed by switching the driving room. In the flow shown in Figure 2, the filament current is set in advance (assuming the acceleration voltage is constant), which is the same as setting the emission current), but according to actual measurements, the acceleration voltage In order to obtain an emission current of 100 mA at 500 V, the filament current must be set to 17 people, but each time the driving room is switched, 1
If seven currents are instantaneously applied to each filament electrode, the life of the filament will be significantly shortened due to rush current. Therefore, when switching, it is almost O.
It is important to gradually (approximately 10 seconds) reach 17A at A, and this soft start function may be included in the ES power supply 100 shown in FIG. may have a time constant of In addition to the above-mentioned soft start, the filament 300.400 and the ES power supply 100 include a 17A
Switching the output or performing an output cutoff operation while the device is energized must be avoided because it accelerates the deterioration of the components and significantly impairs reliability. Therefore, it is important to provide the BS power supply 100 or the control device 200 with the above-mentioned contents.

FIG. 3 shows an example of the ES power supply 100 embodying the above contents, and shows only the parts necessary for explanation.
A schematic source of the power supply is shown.

In the figure, the part surrounded by straight lines is the acceleration power source, and the others are the filament power sources. The filament power supply is
It is floating on the acceleration power supply. In principle, the filament power source is a constant current power source, and the acceleration power source is a constant voltage power source.

First, the filament power supply will be explained. In the figure, AC 200V passes through an electromagnetic relay 101 and a DC generator 10 consisting of a transformer, rectifier, and filter circuit.
2 becomes a DC voltage, and the control transistor 103,
Through the contacts of the detection resistor 104 and the electromagnetic relay 105, and the switched filament electrode 300 or 40
0 and returns to the tributary rectifier 102. The current detected by detection resistor 104 is applied to resistors 108, 109 . and an operational amplifier 110, and a resistor 111 and a transistor 112 control a control transistor 103. A current is set to the operational amplifier 110. 6
The reference voltage is given a time constant by an integrator composed of a resistor 113, a °7 capacitor 114, and an operational amplifier 115, and inputted through a resistor 116. C soft start function) The detection voltage of the detection resistor 104 is input to the comparator 118 via the resistor 117. A reference value to the comparator is provided by resistor 119 and reference voltage 120. The output of the comparator is inverted when the filament current becomes less than a certain value (for example, 0.I A ), and is given to the control unit 124 as a contact signal of a relay 123 driven by a resistor 21 and a transistor 22. . The control unit 124 receives a control signal as an auto-remote signal from the control device 200 shown in FIG.
A signal for operating the manual local power supply is also received from the operation panel of the power source 100, and this signal is switched by the mode switching signal.

Next, the acceleration power source within the dotted line will be explained. Output AC of electromagnetic relay 101! The DC voltage from the DC generator 125 composed of a transformer and a rectifying filter is
It is applied in series with the control transistor 126 and the load (in this case a filament applied via the contacts of the logical relay 105).

The divided voltage of resistors 127 and 128 connected in parallel with the load and the reference voltage 129 are connected to resistors 130 and 131, respectively.
is input to the error amplifier 132 by. Resistor 133 is a feedback resistor of error amplifier 132. The output of the error amplifier 132 passes through a resistor 134 and controls a transistor 135.
The output controls the control transistor 126 to maintain a constant voltage across the load. The emission current is the electronic current e- shown in FIG. 5, which is displayed by the current display meter 128 and outputted to the control device 20000 shown in FIG. 1 via the control section 124. Capacitor 136 and diode 137 are for absorbing surge when relay 105 is switched.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the ion implantation device, Fig. 2 is a conceptual diagram of the electron shower system, Fig. 3 is a schematic diagram of the electron shower system configuration, and Fig. FA4 is the electron shower control system flow filament.

Claims (1)

[Claims] 1. In an ion implantation machine equipped with two implantation chambers, an electron shower electrode provided in each of the implantation chambers, and an electron shower power supply for supplying power to the electron shower electrodes, the two electron shower A first means for independently setting the current value of the filament current supplied to the filament by an electrode, and a second means for causing the filament current to reach a preset current value with a specific time constant. and third means for switching the electron shower power source to the electron shower electrode provided in the switched implantation chamber in conjunction with switching between the two implantation chambers. Machine.