JPS6139356A - Ion implanting equipment - Google Patents

Abstract

PURPOSE:To make the amount of ion implanted into a wafer controllable regardless of the surface state of the wafer by providing an ion-current detector ahead of the spot where ion beam is shot into a detached magnet, and controlling the amount of ion implanted into the wafer by means of the detected value of said detector. CONSTITUTION:Ion-types are ported by shooting an ion beam 2 to a detached magnet 3 from an ion source 1, and implantations is made while scanning a beam 4 across a wafer 6 fixed on a rotary disk 5, thus processing is made for implantation of impurities. At this time, a partial ion detector 15 having an opening at the center is set in front of a detached magnet 3, and a partial ion beam 16 in proportion to the implanting ion beam 4 is taken out, thereby, the ion source 1, magnetic field 3 and scanning control system etc. are controlled through an implanting control system 14. Accordingly, it is possible to control ion-implanting amount exactly regardless of the surface states such as the dirt etc. of the wafer 6 by ion beam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an ion implantation apparatus used for implanting impurities in the manufacturing process of semiconductor devices such as LSIs.

[Background of the invention]

In this type of conventional ion implantation equipment, the amount of ions implanted into the wafer is determined by electrically heating the wafer and a disk supporting the wafer, and detecting the amount of ions injected into the wafer by electrical current. By doing so, you are in control.

FIG. 3 shows a schematic diagram of a conventional ion implantation device.

In the figure, for example, when forming the P+ layer, as an impurity,
Use boron. Boron trifluoride (BFs) as a gas
is often used. BFa gas is supplied to the ion source IK, and the ion source I generates plasma using electrons, microwaves, and a superimposed magnetic field to generate ions. Ion source 1
is usually at a high potential of 20 to 200 kV9, and due to the electric field,
The entire ion beam 2 is extracted with a large current. The ion beam incident on the separation magnet 3 is sorted into ion species that fly in a trajectory determined by the voltage at which the ions are accelerated and the strength of the separation magnetic field, based on the mass and charge ratio of the ions.

When BF or gas is used, 11B- (unloaded boroy ion with a mass number of 11) is often used, and corresponds to the implantation beam 4 in the figure. The implantation chamber is equipped with a rotating disk 5 for uniformly implanting ions and keeping the temperature of the wafer low, and a plurality of wafers 6 are mounted around the rotating disk 5. In order to perform uniform implantation, the rotating disk 5 rotates at a constant high speed and scans the implanted ion beam 4 in the lateral direction or scans the ion beam. As an example of scanning the rotating disk 5, the scanning mechanism 7 and the scanning control system 8 are inversely proportional to the radial direction,
This figure shows a case where uniform implantation is performed by performing scanning control in accordance with the increase or decrease of the implanted ion beam 4. Ion source power supply 1
2. The magnetic field power supply 11 and the driving current detection system 9 are installed! D.C.P.
The entire system is controlled by a driving control system 14 that performs centralized control by the U. The system including the ions, the mulline and the rotating disk 5 is kept under high vacuum. The total ion current 10 and implantation current 13 drawn from the ion source 1 are each detected and controlled.

However, recently in such ion implantation equipment, LS
Due to the miniaturization of I and the manufacturing process, the surface of the sea urchin has an insulating layer,
As more and more products come with photoresist, the ions implanted into the wafer 6 accumulate, and the photoresist undergoes degassing phenomenon due to ion beam irradiation. It is difficult to accurately measure the implantation current 13 because the ion beam is neutralized by collision with neutral particles, and the amount of secondary electrons generated due to dirt or the like fluctuates. Due to this,
The uniformity and reproducibility of the implanted amount is impaired, which has a negative impact on the quality of the device. On the other hand, OW Energy E
lectrons U, S, P 3507705J
``Method and device for strengthening the neutralization of positively charged ion beams'', such as Japanese Patent Publication No. 57-87056 J, are equipped with an electron supply device as a means of preventing charge-up on the surface of the sea urchin. However, accurate detection of the amount of ions is difficult to control reproducibly due to fluctuations in secondary electrons caused by dirt around the sea urchins.

[Purpose of the invention]

The object of the present invention is not to detect the ion current around the wafer and the implantation chamber supporting the wafer as in the past, but to detect the amount of ions proportional to the implantation ion current. An object of the present invention is to provide an ion implantation device that can set an implantation ion current and thereby accurately control the amount of ions implanted.

[Summary of the invention]

In the vicinity of the wafer and the implantation chamber that supports the wafer, it is difficult to accurately and reproducibly detect the ion current due to secondary causes such as contamination of the ion beam. Of course, in consideration of the fact that the formation of an insulating layer on the surface of the sea urchin is a serious cause of ion current detection errors, the present invention installs an ion current detection device in front of the separation magnet or the implantation chamber to indirectly detect the implanted ions. By detecting the current, the amount of implanted ions can be controlled regardless of the surface condition of the wafer.

[Embodiments of the invention]

FIG. 1 is a configuration diagram showing an embodiment of an ion implantation apparatus according to the present invention. In this figure, the same reference numerals as in FIG. 3 indicate the same materials. In FIG. 1, a partial ion detector 15 having an opening in the center is installed in front of a branch magnetic field 3 to detect a portion of the total ion beam 2 extracted from the ion source 1. For example, as the center beam, 9 of the total ion beam 2
The 0chi passes through and the 10chi is received by the partial ion detector 15.

Since the required implant ion beam 4 is proportional to the total ion beam 2, the implant ion beam 4 and the partial ion beam 16 are proportional. By detecting and controlling the partial ion beam 16, it is possible to control the amount of implanted ions. The structure of the partial ion detector 15 may be one having an opening in the center, or two bar-shaped slits on the upper and lower sides or on the left and right sides. Furthermore, change the position, rotate the two rod-shaped slits, change the furniture,
It is also possible to variably set the amount of detected ions.

FIG. 2 shows a mass spectrum of boron trifluoride (BFs) gas. The number on the upper left of the letter indicating the element indicates the mass number; in the case of boron, the mass numbers are lO and 11, and IIB is often used as the ion beam used for implantation. The total ion beam 2 is the sum of each peak appearing in this mass spectrum. Since the abundance ratio of isotopes is constant, implantation can be controlled more accurately by detecting an isotope different from that of the ion beam used for implantation.

It is also possible to accurately control the amount of implanted ions by detecting not the entire ion beam 2 but the separated ion beam 4' (or isotope ion amount - 4''). Ion beam 4'
A separated ion detector 19 is installed at the position of the isotope ion beam 4'', and a separated ion detection system 21 detects the separated ion current 20 or the isotope ion beam current 20', thereby controlling the implantation current 13. The orbit of the separated ion is
Since it is determined by the theory of mass spectrometry based on the ion accelerating voltage and separation magnetic field strength, it is necessary to install a separated ion detector at that position, and a variable-position arrangement is desirable.

A driving control system 14 controls uniform driving and other aspects.

In this way, it is possible to prevent fluctuations in the amount of implanted ions due to changes in the amount of secondary electrons generated due to the surface condition of the wafer, neutralization of the ion beam due to degassing, and dirt, etc., resulting in reproducible implantation. In addition, it is not necessary to accurately control the amount of electrons in the electron shower device that prevents wafer charge-up, and the vacuum evacuation system around the wafer can be simplified.

〔Effect of the invention〕

As is clear from the above explanation, according to the ion implantation apparatus according to the present invention, it is possible to accurately control the amount of ion implantation.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the ion implantation device according to the present invention, FIG. 2 is an explanatory diagram for explaining the operation of the ion implantation device according to the present invention, and FIG. FIG. 2 is a configuration diagram showing an example of a driving device. 1... Ion source, 2... Total ion beam, 3...
Separation magnetic field, 4...Implementation ion beam, 4'...Isotope ion beam, 4''...Separation ion beam, 5
... Rotating disk, 6... Wafer, 7... Disc scanning drive mechanism, 8... Disc scanning control system, 9... Implanting current detection system, 10... Total ion current , 11... magnetic field power supply,
12... Ion source power supply, 13... Implanting ion beam, 14... Implanting control system, 15... Partial ion detector, 16... Partial ion current, 17... Isotope ion Detector, 18... Separation slit, 19... Separated ion detector, 20... Separated ion current, 21... Separated ion detection system.

Claims (1)

[Claims] 1. In an ion implantation apparatus comprising an ion source, a separating magnet, and an implanting chamber equipped with a wafer, a portion of the ion beam is detected in front of the ion beam entering the separating magnet;
An ion implantation apparatus characterized in that the amount of ions implanted into a wafer is controlled based on this detected value. 2. In an ion implantation device consisting of an ion source, a separation magnet, and an implantation chamber equipped with a wafer, among the ion beams that pass through a separation power and are separated according to mass and charge ratio, the ion beam that differs from the implantation ion beam An ion implantation device characterized by controlling the amount of ions implanted into a wafer by detecting an ion beam. 3. An ion implantation apparatus according to claim 2, wherein the amount of ions implanted into the wafer is controlled by detecting the ion beam of isotopes of the implanted ion beam.