JPH0896744A - Ion implanting device - Google Patents

Abstract

PURPOSE: To prevent the decrease of gate pressureproof generated according to a chargeup phenomenon, by providing a scan magnet which scans an electron, generated in an electron generating means, in a direction of a semiconductor substrate. CONSTITUTION: A semiconductor substrate 13 is supported in the peripheral edge part of a conductive clamp ring 20 connected to a grounding electrode 22. A doze CPU, counting a number of positive impurity ions implanted by counting in the halfway of supply to the semiconductor substrate 13 an electron for electrically neutralizing, is provided between the semiconductor substrate 13 and the grounding electrode 22. In a plasma flood gun 12 compensating insufficiency of an electron supplied from the grounding electrode 22, Ar gas 18 is supplied from a gas introducing port 17 into an arc chamber 14, to perform a plasma discharge by applying voltage across filament 14a-arc chamber 14, and a generated electron is used for neutralization. The plasma flood gun 12 is provided with a draw out electrode 15 drawing out an electron from the arc chamber 14 and a scan magnet 16 for scanning the electron.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for manufacturing a semiconductor integrated circuit device, and more particularly to forming a p-type or n-type conductivity type region on a semiconductor substrate by causing impurity ions to collide with the semiconductor substrate. It is effective for use in the ion implantation technology.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor integrated circuit device, an ion implantation process for introducing impurity ions into a semiconductor substrate or an etching process for etching a patterned semiconductor substrate collides positive or negative charged particles with the semiconductor substrate. The processing is performed by making In these processes, charged particles that have collided with the semiconductor substrate, for example, positive ions, are electrically neutralized by the electrons supplied from the ground electrode connected to the semiconductor substrate via the clamp ring. However, when the supply speed of electrons or holes supplied to the number of charged particles supplied to the semiconductor substrate is delayed, a phenomenon in which the semiconductor substrate is charged by the charges of the charged particles, that is, a so-called charge-up phenomenon occurs.
This tendency is particularly remarkable in a high-current ion implanter.

In a semiconductor integrated circuit device (MISIC) including an insulated gate field effect transistor, when such a charge-up phenomenon occurs in a gate electrode when forming a source and drain regions of a MOS transistor, for example, gate oxidation is performed. There is a problem that the film is destroyed. Particularly in recent years, the miniaturization of MOSIC has progressed, and the gate oxide film has been thinned accordingly, and it is easy to be destroyed by a minute charge-up phenomenon. In particular, in the ion implantation process, impurity ions are implanted into the semiconductor substrate and left in a form of being electrically neutralized with electrons, so that electrons are immediately supplied to the implanted impurity ions so as not to cause a charge-up phenomenon. There is a need.

Regarding the ion implantation apparatus, "Super LS"
I Manufacturing / Testing Equipment Guidebook, 1988 Edition Electronic Materials Separate Volume "(published by the Industrial Research Institute), pages 58 to 64. For example, on page 59, left column, lines 1 to 11 of the same document, "In fine elements, thinning progresses, and it is also an important subject to prevent the film breakdown during ion implantation. The wafer is charged during the implantation and causes electrostatic breakdown.Ion implantation equipment needs improvement to reduce this charge amount.It depends on the device structure, but a voltage of several V or less is desired. The important point is to increase the beam diameter and make it uniform.There is also a method to forcibly neutralize the ions with an electro-flad gun,
Although highly effective, stabilization of the electroflood gun and electroflood control with a charge monitor is desired. Is stated.

FIG. 4 (a) shows an outline of an electro-flad gun, and FIG. 4 (b) shows the outline of a plasma-flad gun. The electro-flag gun 29 applies the thermoelectrons 32 generated in the filament 31 to the target block 35, and secondary electrons 36 are emitted from the target block 35. The secondary electrons 36 generate the ion beam 34 or the charged semiconductor substrate 3
Neutralization of impurity ions is carried out by utilizing the fact that the impurity ions are attracted to 3. Further, the plasma flood gun 38 causes Ar gas to flow in the arc chamber 39, applies a voltage between the filament 40 and the arc chamber 39, and neutralizes the impurity ions by the electrons 46 generated by the plasma discharge.

[0006]

However, when an electro-flad gun is used, a high voltage is applied to generate a secondary electron to generate a thermoelectron, but the thermal electron has a high energy and is more than necessary. Secondary electrons are supplied, which may cause a negative charge-up phenomenon.
In addition, the present inventor conducted a test using a semiconductor substrate for damage evaluation in order to evaluate the ion neutralization technique of the plasma flood gun. As a result, it was found that the breakdown voltage of the semiconductor substrate having the increased implantation beam amount was low at the peripheral portion of the substrate. The present inventor has found that the supply amount of the neutralizing electrons of the plasma flad gun varies in the substrate surface, and the electron supplying amount is smaller in the peripheral portion of the substrate far from the supply source of the neutralizing electrons than in the central portion of the substrate. Since the neutralizing electrons may not be sufficiently supplied, and the current trend is to increase the diameter of semiconductor substrates, such a phenomenon becomes remarkable, and the inventors have made earnest studies.

In view of the above, the present invention prevents, in an ion implantation apparatus, the supply of neutralizing electrons in the surface of the semiconductor substrate from being stabilized, thereby preventing the gate breakdown voltage from being lowered due to the charge-up phenomenon, and thus to increase the diameter of the semiconductor substrate. However, it is an object to provide a technique capable of performing stable ion implantation processing.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0009]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, by impinging the impurity ions on the semiconductor substrate with an ion beam, an impurity ion supply unit for forming a desired conductivity type region on the semiconductor substrate and electrons for electrically neutralizing the impurity ions are generated. The electron generating means of the ion implanting device having the electron generating means is provided with a scan magnet for scanning the electrons toward the semiconductor substrate.

[0010]

Since the scan magnet for scanning the electrons generated by the electron generating means in the direction of the semiconductor substrate is provided, the supply direction of the electrons can be controlled by the magnetic field. Therefore, the charge of the semiconductor substrate can be neutralized efficiently and uniformly by scanning in the same direction and at the same speed as the ion beam, and the reduction of the gate breakdown voltage caused by the charge-up phenomenon due to the accumulation of impurity ions can be prevented. Therefore, a stable ion implantation process can be performed even on a large-diameter wafer.

[0011]

EXAMPLE An example of using the present invention in an ion implantation apparatus will be described below.

FIG. 1 is a diagram showing an outline of an ion implantation apparatus 1. The main part of the ion implantation apparatus 1 is an ion source unit 4, an acceleration unit 5 for accelerating the ion beam 9, a mass spectrometric unit 6 for extracting only target impurity ions from the ion beam 9, and an ion beam 9 for scanning at a constant speed. It is composed of a scan unit 7, an angle collector unit 8 for correcting the angle of the ion beam 9, and an implantation chamber 10. Each unit is kept in a high vacuum to prevent generation of neutral particles due to collision between ions and residual gas molecules. It A plurality of semiconductor substrates 13 are set on the rotary disk 10a of the implantation chamber 10. When the semiconductor disks 13 reach the implantation position 11, the ion implantation process is performed by rotating the rotary disks 10a at high speed. In the vicinity of the injection position 11, a neutralizing electron supply means for electrically neutralizing the charge of the impurity ions, for example, a plasma flood gun 12 is provided. FIG. 2 shows the relationship between the electrons supplied from the plasma flood gun 12 and the ion beam. The semiconductor substrate 13 is supported at its peripheral portion by a conductive clamp ring 20 connected to a ground electrode 22, and electrons for electrically neutralizing positive impurity ions are electrically connected to the semiconductor substrate 13 via the clamp ring 20. Is supplied to. Between the semiconductor substrate 13 and the ground electrode 22,
A dose CPU 21 that counts the number of implanted ions is provided. The dose CPU 21 counts the number of implanted positive impurity ions by counting electrons for electrically neutralizing while being supplied to the semiconductor substrate 13.

The plasma flood gun 12 which compensates for the shortage of electrons supplied from the installed electrode 22 includes an arc chamber 14
Ar gas 18 is supplied into the chamber from a gas inlet 17, a voltage is applied between the filament 14a and the arc chamber 14 to cause plasma discharge, and electrons generated thereby are used for neutralization. In the present invention, the plasma flood gun 12 has an extraction electrode 15 for extracting electrons from the inside of the arc chamber 14,
Also, a scan magnet 16 is provided for scanning the electrons similarly to the ion beam. By providing the extraction electrode 15, the amount of electrons extracted from the inside of the arc chamber 14 can be controlled. Further, since the scan magnet 16 is provided, the neutralizing electrons can be supplied in the same direction and at the same speed as the ion beam 9.

Next, the ion implantation method of the present invention will be described. The ion beam 9 is first ionized by arc discharge by introducing gas into the arc chamber of the ion source unit 4. The ions extracted to the outside of the arc chamber by the arc voltage are extracted again at the extraction portion voltage, and a voltage is applied to the accelerating portion 5 so that the implantation depth is required.
After that, only the impurity ions necessary for implantation are selected by the mass spectrometric section 6. The selected ion beam 9 is horizontally scanned by the scanning unit 7 at a constant speed, and is angle-corrected by the angle collector unit 8 in parallel with the semiconductor substrate, and is introduced into the implantation chamber 10. On the other hand, the semiconductor substrate 13 is the injection chamber 1
A plurality of rotating disks 10a are set on the rotating disk 10a of 0, and the rotating disks 10a are rotated at high speed so that the semiconductor substrate 13 is at the injection position
When the number reaches 1, the ion implantation process is performed. During the implantation, the rotating disk 10a rotates at a high speed, so that the set semiconductor substrates 13 are all uniformly implanted. or,
The implanted impurity ions 9a are counted as an implantation amount by an ammeter provided in the dose CPU section. At the time of ion implantation, in the plasma flood gun 12, first, Ar gas 18 is supplied into the arc chamber 14 from the gas inlet 17, and a voltage is applied between the filament 14 a and the arc chamber 14 to cause plasma discharge. Accordingly, a large amount of low energy electrons can be generated. In the present invention,
Electrons generated by plasma discharge are extracted from the arc chamber by the extraction electrode 15, and the scan magnet 16 scans the electrons in the same direction and at the same speed as the ion beam 9. The scanned electrons electrically neutralize the impurity ions of the ion beam 9 or the impurity ions charged in the semiconductor substrate 13. As a result, the charge of the semiconductor substrate can be neutralized efficiently and uniformly by scanning in the same direction and at the same speed as the flow of charged particles. Therefore, it is possible to prevent the gate breakdown voltage from being lowered due to the charge-up phenomenon and to perform stable ion implantation processing even on a large-diameter wafer.

Next, the function and effect of the present invention will be described.

(1) Since the electron generating means is provided with a scan magnet for scanning electrons in the direction of the semiconductor substrate, scanning is performed in the same direction and at the same speed as the ion beam to efficiently neutralize the charge on the semiconductor substrate. And can be performed uniformly. Therefore, it is possible to prevent the gate breakdown voltage from being lowered due to the charge-up phenomenon and to perform stable ion implantation processing even on a large-diameter wafer.

(2) The electron generating means generates Ar electrons by supplying Ar gas into the arc chamber and applying a voltage between the filament and the arc chamber to generate plasma discharge. Can generate energetic electrons. Therefore, since the supply of neutralizing electrons can be stabilized, the ions can be efficiently and uniformly neutralized by using the scan magnet.

(3) Since the extraction electrode for extracting the electrons from the electron generating means is provided, the amount of electrons extracted from the electron generating means can be controlled. Therefore, when used in combination with the scan magnet, electrons can be scanned in the same direction and at the same speed as the flow of the ion beam to efficiently and uniformly neutralize the charge on the semiconductor substrate. As a result, it is possible to prevent the gate breakdown voltage from being lowered due to the charge-up phenomenon, and to perform stable ion implantation processing even on a wafer having a large diameter.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, in the above-described embodiment, an example of using the ion implantation technique for forming the source region and the drain region of the MOS transistor has been described, but it may be used for forming the channel stopper or well of the complementary MOS (CMOS) transistor. Of course. Further, in the above-described embodiment, the plasma flood gun is used to generate the neutralizing electrons. However, as shown in FIG. 3, the electron gun 25 and the target block 26 are provided in the chamber 24, and the electron is generated in the chamber 24. Secondary electrons 28 are generated by irradiating the target block 26 with the electron beam 27 from the gun 25, and the secondary electrons 28 are generated.
The same effect as in the above-described embodiment can be obtained by using the extraction electrode 15 to extract and scanning with the scan magnet 16.

The present invention is particularly effective when used in a high-current ion implantation apparatus, and can be easily applied even if further fine processing is required using a semiconductor substrate having a large diameter in the future. Is.

[0021]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, the impurity ions are made to collide with the semiconductor substrate by an ion beam to form a desired conductivity type region on the semiconductor substrate, and an electron for electrically neutralizing the impurity ions. The electron generating means of the ion implantation apparatus having an electron generating means for generating a magnetic field is provided with a scan magnet for scanning electrons in the direction of the semiconductor substrate, so that the same direction and same speed as the ion beam are obtained. By scanning with, the charge of the semiconductor substrate can be neutralized efficiently and uniformly. Therefore, it is possible to prevent the gate breakdown voltage from being lowered due to the charge-up phenomenon and to perform stable ion implantation processing even on a large-diameter wafer.

[0023]

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an ion implantation apparatus which is an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between electrons and an ion beam supplied from a plasma flood gun of an ion implantation apparatus which is an embodiment of the present invention.

FIG. 3 is a diagram showing an outline of an electron generating means of an ion implantation apparatus which is another embodiment of the present invention.

FIG. 4A is a schematic view of an electroflad gun which is a conventional electron generating means, and FIG. 4B is a schematic view of a plasma flood gun.

[Explanation of symbols]

1 ... Ion implanter, 2 ... High-voltage power supply, 3 ... Gas box, 4 ... Ion source section, 5 ... Accelerator section, 6 ... Mass spectrometric section, 7 ... Scan section, 8 ... Angle Collector part, 9 ... Ion beam, 9a ... Impurity ion, 1
0 ... Injection chamber, 10a ... Rotating disk, 11 ... Injection position, 12 ... Plasma flad gun, 13 ... Semiconductor substrate, 14 ... Arc chamber, 14a ... Filament, 15 ... Extraction electrode, 16 ... … Scan magnet,
17 ... Gas inlet, 18 ... Ar gas, 19 ... Electron flow, 19a ... Electron, 20 ... Clamp ring, 21 ...
... Dose CPU, 22 ... Ground electrode, 23 ... Electron generating means, 24 ... Chamber, 25 ... Electron gun, 26 ... Target block, 27 ... Electron beam, 28 ... Secondary electron, 29 ... Electrofurado gun, 30 ... Reflector, 31 ... Filament, 32 ... Thermoelectrons, 33
...... Semiconductor substrate, 34 …… Ion beam, 35 …… Target block, 36 …… Secondary electron, 37 …… Faraday, 38 …… Plasma fluff gun, 39 …… Arc chamber, 40 …… Filament, 41 …… Gas inlet, 4
2 ... Arc ammeter, 43 ... Faraday, 44 ... Semiconductor substrate, 45 ... Ion beam, 46 ... Electron

Claims (3)

[Claims] 1. Impurity ion supplying means for forming a desired conductivity type region on the semiconductor substrate by bombarding the semiconductor substrate with impurity ions by an ion beam, and electrically neutralizing the impurity ions. And an electron generating unit for generating electrons, wherein the electron generating unit includes a scan magnet for scanning the electrons toward the semiconductor substrate. Semiconductor substrate processing apparatus. 2. The electron generating means supplies Ar gas into the arc chamber and applies a voltage between the filament and the arc chamber to cause plasma discharge,
The ion implanter according to claim 1, which is a plasma flood gun for generating electrons. 3. The electron generating means is provided with an extraction electrode for extracting electrons generated in the arc chamber to the outside of the arc chamber.
Alternatively, the ion implantation apparatus according to item 2.