JPH0322340A - Ion implanter - Google Patents

Abstract

PURPOSE:To neutralize the accumulated charges of an ion implanted body neither too much nor too less and obtain the neutral state by providing an electron emitting means selected with the electron emission quantity via the charged voltage by the accumulated charges of the ion implanted body. CONSTITUTION:An electron emitting means, e.g. a thermoelectron emitting means 2, is provided to face the shift position where an ion implanted body 1 is moved at the time of ion implantation at the position different from an ion radiation section to the ion implanted body 1. The electron emitting means extracts and radiates electrons to the ion implanted body 1 by the charged voltage of the ion implanted body 1. The electron radiation is controlled by the charged state of the ion implanted body 1 and invariably neutralized neither too much nor too less. The surface can be surely neutralized neither too much nor too less by hardly depending on conditions such as the pattern, device structure, surface material and surface state of the ion implanted body 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an ion implantation device used, for example, to introduce impurities into semiconductors.

[Summary of the invention]

The present invention relates to an ion implantation apparatus, and is provided with an electron emitting means in which the amount of electron emission is selected depending on a charging voltage due to accumulated charges of the ion implanted object, at a position that can face the ion implanted object, and to emit electrons. By irradiating the ion implanted object with electrons from the means, the charge caused by the ion implantation is neutralized, and by adopting such a structure, it is possible to measure the amount of ions implanted into the ion implanted object. To neutralize accumulated charges in an ion-implanted body in just the right amount and to obtain a neutral state without impairing control.

[Conventional technology]

In the manufacturing process of various semiconductor devices, ion implantation is often applied, for example, to introduce impurities into semiconductors. In this case, if there is an insulating layer on the surface of the ion implanted object, or if the support supporting the ion implanted object is electrically floating due to a cooling device or the like, As ions are implanted, charge is accumulated in the ion-implanted object, which becomes electrically charged. On the other hand, as semiconductor integrated circuits become more highly integrated and smaller, thin film transistors, for example, become thinner, or surface 1! ! As the edge layer becomes thinner, and the gate insulating layer of MOS (insulated gate field effect transistor) becomes thinner, the occurrence of defective products increases due to discharge breakdown of the insulating layer or semiconductor layer due to surface charging. . Alternatively, uneven surface potential due to surface charging may cause non-uniformity in the amount of ions implanted. These inconveniences become more noticeable, especially during high-concentration ion implantation because the charge becomes larger.

This charging is basically an unavoidable problem as long as the ion implantation method involves irradiating the object to be ion implanted with a charge beam, and various remedies have been proposed. For example, Japanese Unexamined Patent Publication No. 10451/1983 discloses an electronic shower method. This ion implantation apparatus using one type of electronic shower neutralizes the positive charge caused by the ion beam with the negative charge caused by secondary electrons, and is an extremely effective method for neutralizing charge. However, in this case,
When using a general control method in which the amount of ion implantation is detected and measured using this electrical quantity and controlled, the implanted ions are neutralized by an electron shower, which obstructs accurate detection and makes it difficult to accurately determine the amount of ion implanted. This results in the inconvenience of hindering accurate measurement control.

In order to avoid such interference with the measurement of the ion implantation amount, for example, Japanese Patent Application Laid-Open No. 63-12854
As disclosed in Japanese Patent No. 3, there is an ion implantation apparatus in which an electron flood mechanism is provided at a position different from the ion beam irradiation part.

However, in reality, the amount of ion implantation, eg, the ion implantation pattern or surface pattern into the semiconductor, the device structure, the material of the surface, eg, Sin. , polycrystalline silicon, photoresist, and the like, it is quite difficult to set conditions for the amount of secondary electron irradiation to obtain the optimum neutralization effect by this electron shower or flood.

[Problem to be solved by the invention]

The present invention enables an ion implanter to reliably bring the surface into a neutralized state in just the right amount, without depending on conditions such as the pattern, device structure, surface material, surface condition, etc. of the object to be ion implanted. Make it.

[Means to solve the problem]

For example, as shown in FIG.
Specifically, the ion-implanted body (1)
) at a position different from the ion irradiation part to the ion-implanted body (1), an electron-emitting means, specifically, for example, a thermionic-emitting means (2 ) will be established.

The electron emitting means (2) is configured to extract and irradiate electrons toward the ion implanted object (1) depending on the charging voltage of the ion implanted object (1).

[Effect]

According to the above-mentioned apparatus of the present invention, the thermionic emission means (2) is provided at a position facing the ion-implanted object while the ion-implanted object is moving during ion implantation, and this emits electrons of the ion-implanted object (1). Since thermionic electrons are extracted by the voltage generated by the charging on the surface and irradiated with electrons toward the ion implanted object (1), the electron irradiation is controlled by the charged state of the ion implanted object (1). It will always be neutralized in just the right amount.

In other words, the electron irradiation to the ion implanted object is carried out by the surface structure of the ion implanted object (1). Electron irradiation is performed by extracting and drawing electrons by the voltage itself due to the charged state, without depending on the surface state or material. If this is maintained in a neutralized state, the electron beam will not be extracted and the electron beam irradiation will continue. Since the neutralization is prevented from occurring, a good neutralization state can always be obtained, that is, just the right amount.

Moreover, the electron irradiation position for this neutralization is set at a different position from the ion beam irradiation position, which is done during ion implantation work, so the ion beam is not neutralized, so the implanted ions The amount of ion implantation can be reliably measured by electrical detection without being hindered by the irradiated electrons.

〔Example〕

An example of an ion implantation apparatus according to the present invention will be explained in detail with reference to the drawings. In the figure (3) is the ion-implanted object (1
) is arranged in the ion implantation chamber where ion implantation work is performed, and (4) is a disc-shaped support for supporting the ion implanted object (1), for example a semiconductor wafer, and a rotary drive motor (not shown). The rotating shaft (5) rotates as shown by arrow a, and the entire reciprocating direction is perpendicular to the axial direction of the rotating shaft (5) as shown by arrow b in the figure. made to migrate.

A plurality of objects to be ion-implanted (1), for example, semiconductor wafers, are placed on this disk-shaped support (1), and an ion beam (6) is implanted from an ion generator (not shown). is irradiated through the ion implantation window (7) of the ion implantation chamber (3) to a predetermined position on the support (4) in the ion implantation chamber (3).

The ion beam (6) irradiates each ion implanted object (
Regarding 1), ion implantation is repeatedly performed on one ion-implanted object (1) with respect to high-speed rotation of its rotation axis (5) and slower rotation of the reciprocating movement, and the wafer position is changed with respect to the reciprocating movement of arrow b. The entire area can be irradiated with ion implantation. In this case, although not shown,
The amount of ion irradiation is measured as a well-known quantity of electricity by a detection and measurement device that detects it, and the amount of ion implantation is controlled. At the same time as this ion implantation operation, the ion implanted object (
A thermionic emission means (2) is provided at a position opposite to 1).

This thermionic emission means (2) includes, for example, a plurality of filaments (8) coated with a cathode material arranged in parallel in a direction perpendicular to the transition direction of the above-mentioned arrow b, as shown in FIG. The voltage applied to this filament, which is connected or independently arranged so that electron irradiation can be applied to all positions according to the rotation and movement of the ion-implanted object (1), is as follows. Electrons can be extracted by a minute positive potential due to charging of the ion-implanted body (1) facing the ion-implanted body (1), but when the surface charge of the ion-implanted body (1) is neutralized, electrons are not emitted. hold. In addition, this thermionic emission means (2)
For example, a grill-shaped control electrode (9) as shown in FIG. ) Thermionic electrons may be extracted based on the potential difference with the surface charge of the ion-implanted body (1) to irradiate the ion-implanted body (1) with electrons. (10) indicates a filament power supply.

[Effects of the Invention] According to the above-described apparatus of the present invention, the thermionic emission means (2) is provided at a position facing the ion implanted object during the movement of the ion implanted object during ion implantation, and this Since thermionic electrons are extracted by the voltage generated by charging on the surface of the body (1) and irradiated with electrons toward the ion implanted body (1), the electron irradiation is caused by the { It is controlled in the jF electrical state and is always neutralized in just the right amount.

In other words, electron irradiation to the object to be ion-implanted is performed by extracting and drawing electrons by the voltage itself depending on the charged state, without depending on the surface structure, surface condition, material, etc. of the object to be ion-implanted (1). If this is maintained in a neutralized state, the electron beam will not be extracted and the electron beam irradiation will not be performed, so a good neutralized state can always be obtained, that is, with just the right amount and not enough. .

Moreover, the electron irradiation position for this neutralization is set at a different position from the ion beam irradiation position, which is done during ion implantation work, so the ion beam is not neutralized, so the implanted ions The amount of ion implantation can be reliably measured by electrical detection without being hindered by the irradiated electrons.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of the ion implantation device according to the present invention, FIG. 2 is a diagram showing the filament arrangement pattern of the thermionic emission means, and FIG. 3 is a front view of an example of the control electrode. shows. (1) is the ion implanted object, (6) is the ion beam, (2
) is a thermionic emission means.

Claims (1)

[Claims] An electron emitting means is provided at a position that can face the object to be ion-implanted, and the electron-emitting means extracts and irradiates electrons toward the object to be ion-implanted using a charging voltage of the object to be ion-implanted. An ion implantation device made like this.