JPH0473851A - Device and method for ion implantation - Google Patents

Abstract

PURPOSE:To protect an irradiated target from an abnormal ion beam current by providing a detection system for monitoring ion beam current, and interrupting the irradiation when a fixed value or more of ion beam is emitted to the irradiated target. CONSTITUTION:When an ion beam 11a is emitted to an irradiated target 15 from an ion generating source 11, the ion beam 11a is deflected and driven by a beam deflecting and driving means 12, and the ion beam 11a emitted to the irradiated target 15 is detected by a beam detecting means 13 and outputted to a control means 14 as a beam detection signal Si. In the control means 14, the beam detection signal Si is compared with a preset beam standard signal SL, and when the beam detection signal Si exceeding the beam standard signal SL is detected, drive control is conducted so that the ion beam 11a is not emitted to the irradiated target 15. Thus, the irradiated target 15 can be protected from the abnormal ion beam 11a.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Application Fields Prior Art (Fig. 4) Means for Solving Problems to be Solved by the Invention (Fig. 1) Working Examples (Fig. 2. (Figure 3) Effects of the invention [Summary] The present invention relates to an ion implantation device, particularly a device that protects an irradiated target from abnormal ion beam current caused by charge-up of an ion source or increase in electron current. A monitoring detection system is installed, and if the target is irradiated with an ion beam exceeding a certain level, the irradiation is interrupted and the beam is irradiated again when the ion beam returns to normal. an ion generation source for irradiating an ion beam with an ion beam; a beam deflection drive means for deflecting and driving the ion beam; a beam detection means for detecting the ion beam and outputting a beam detection signal; and a control means for controlling input and output of the beam detection means, the control means controlling the drive of the beam deflection drive means based on a preset beam reference signal and the beam detection signal. Configure.

[Industrial application field]

The present invention relates to an ion implantation device and an ion implantation method, and more specifically, the present invention relates to an ion implantation device and an ion implantation method, and more specifically, to a device and an ion implantation method for protecting an irradiated target from abnormal ion beam flow caused by charge-up of an ion source or increase in electron current. It is about the method.

In recent years, with the increasing integration and density of semiconductor integrated circuit devices (hereinafter referred to as LSI), when forming impurity diffusion layer regions of transistors, impurity ions are directly implanted into the semiconductor substrate using a resist as a mask. There is.

By the way, the influence of abnormal ion beam current is not so much of a problem when ions are implanted through an oxide film, but when ions are implanted through a resist film, this is called mask damage to the resist film. There is a problem that ion implantation with good reliability cannot be performed due to the occurrence of physical cracks and the like.

Therefore, a detection system that monitors the ion beam current is installed, and if the ion beam exceeds a certain level and the target is irradiated, the irradiation is interrupted and the beam irradiation is performed again when the ion beam current returns to normal. A device and method that can do this is desired.

[Prior Art] FIG. 4 is a configuration diagram of an ion implantation apparatus according to a conventional example.

In the figure, an ion implantation device that implants impurity ions using a resist as a mask includes an ion generator 1 that generates an ion beam 11a, an acceleration and momentum analyzer 2A, a beam deflector 2B, and a beam deflection/drive circuit 2C. An ion detector 3 that detects the ion beam 11a and a system that outputs an implantation control signal S13 based on the ion detection current S11? It consists of n devices 4.

The function of this device is, for example, when forming an impurity diffusion layer region of a transistor, first, an ion beam 11a is generated from an ion generator 1, and the beam 11a is subjected to mass spectrometry processing and then passed through an acceleration and momentum analyzer. It is accelerated by 2A. Further, the accelerated ion beam 11a is deflected by a beam deflector 2B via a beam deflection/drive circuit 2C. Thereby, the ion beam 11a is deflected and irradiated onto the semiconductor substrate 5A to be irradiated. At this time,
When the ion beam 11a is scanned for a desired implantation time, impurity ions can be implanted into the semiconductor substrate 5A other than the mask region of the resist.

Further, the implantation time of the ion beam 11a is determined by monitoring the dry input amount of the ion beam 11a using the ion detector 3. For example, the dry input amount of the ion beam 11a is detected by the integrating circuit 4A in the control device 4, and by comparing it with the reference implantation time, the ion beam 11a is turned off via the central processing unit (hereinafter referred to as CPU) 4B. An injection control signal 513 is output to the beam deflection/drive circuit 2C.

[Problem to be solved by the invention]

Therefore, the ion detector 3 is used for the purpose of monitoring the implantation time of the ion beam 11a. This means that when the semiconductor substrate 5A is irradiated with an abnormal ion beam caused by charge-up of the ion generator 1 or an increase in electron current, the ion detector 3, the integrating circuit 4A and the CP04B
With the detection function, only the dry input amount of the ion beam 11a is monitored, and the abnormal ion beam current itself cannot be detected.

Therefore, the abnormal ion beam resists It! May damage 5B. The effect of abnormal ion beam current due to this is that when ion implantation is performed through a thermal oxide film, etc., there is less damage due to ion collision, but when ion implantation is performed through a resist film, there is a mask caused by ion collision. Physical cracks called damage may occur.

This means that when forming impurity diffusion layer regions, etc. of fine transistors that accompany the recent high integration and density of LSIs,
This is especially noticeable, and there is a problem that reliable ion implantation cannot be performed.

The present invention was created in view of the problems of the conventional example, and includes a detection system that monitors the ion beam current, and when the ion beam exceeding a certain level is irradiated onto the target, the irradiation is stopped. The object of the present invention is to provide an ion implantation device and an ion implantation method that can interrupt the beam irradiation and restart the beam irradiation when the beam irradiation returns to normal.

[Means to solve the problem]

FIG. 1 is a principle diagram of an ion implantation apparatus according to the present invention.

The device includes an ion generation source 11 that irradiates an ion beam 11a onto an irradiation target 15, a beam deflection drive means 12 that deflects and drives the ion beam 11a, and detects the ion beam 11a and outputs a beam detection signal Si. a beam detecting means 13 for detecting the ions, and the ion generating means a11. It comprises a beam deflection drive means 12 and a control means 14 for controlling the input/output of the beam detection means 13, and the control means 14 receives a preset beam reference signal SL and the beam detection signal S.
The drive control of the beam deflection driving means 12 is performed based on The above object is achieved by determining whether the ion beam 11a is in an abnormal state while being monitored, and performing irradiation control processing for the ion beam 11a based on the determination.

[For production]

According to the device of the invention, ion generation i11 1. Beam deflection driving means 12. Beam detection means 13 and control means 1
4 is provided, and the ion beam 11a is driven and controlled based on a preset beam reference signal SL and a beam detection signal Si.

For example, when the ion beam 11a is irradiated from the ion source 11 to the irradiation target 15, the ion beam 11a is deflected by the beam deflection driving means 12. Also,
The ion beam 11a irradiated onto the irradiation target 15 is detected by the beam detection means 13, and the beam 11a is outputted to the control means 14 as a beam detection signal Si.

Therefore, the control means 14 compares the preset beam reference signal SL and the beam detection signal Si, and for example, if the beam detection signal Si exceeding the beam reference signal SL is detected, the ion beam 11a It becomes possible to perform drive control such that the target 15 to be irradiated is not irradiated with the irradiation target 15.

Thereby, the beam detection means 13 can be used not only for the purpose of monitoring the implantation time of the ion beam 11a of the ion detector 3 according to the conventional example, but also as a detection function for detecting the abnormal ion beam itself. This makes it possible to perform drive control to protect the irradiation target 15 from the abnormal ion beam 11a.

Further, according to the method of the present invention, there is an ion implantation method using the apparatus, in which the ion beam 11a irradiated to the irradiation target 15 is monitored, and the ion beam 11a is determined based on the abnormal state of the ion beam 11a. Irradiation control processing for the ion beam 11a is being performed.

Therefore, the abnormal ion beam caused by the charge-up of the ion source 11 and the increase in electron current is transmitted to the irradiated target 1.
If there is a risk that the ion beam will be continuously irradiated with ion beam 5, it can be determined that the ion beam is abnormal by detecting an ion beam current of a certain level or higher. In such a case, it becomes possible to interrupt the ion beam irradiation and perform the beam irradiation again when the situation returns to normal.

As a result, in the initial stage of abnormal ion beam irradiation, the target 15 to be irradiated is protected from damage caused by ion collisions, and it is possible to prevent physical cracks, etc., which are called mask damage, as in the conventional example.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a configuration diagram illustrating an ion implantation apparatus and a control method thereof according to an embodiment of the present invention.

In the figure, an ion implantation device that implants impurity ions using a resist as a mask includes an ion generator 1. Acceleration and momentum analyzer 2A, beam deflector 2B
, a wafer holder 25C is provided, and its external devices include a beam deflection/drive circuit 22C and an ff1I control device 24.
Equipped with:

That is, 21 is an ion generator that is an example of the ion generator s11, and is composed of an electron gun 21A that generates electrons and a gas introduction port 21B that introduces impurity gas such as phosphorus (P) and boron (B). . The function of the ion generator 21 is to ionize impurity gas and generate a P ion beam or a B ion beam.

Reference numerals 22A to 22C respectively indicate an acceleration and momentum analyzer and a beam deflection/drive circuit of the beam deflection/drive means 12. - The acceleration and momentum analyzer 22A uses the ion beam 2 from the ion generator 21.
1a. The beam deflector 22B consists of a horizontal deflector 201 and a vertical deflector 202, and directs the ion beam 21a to the semiconductor substrate vi25, which is the target 15 to be irradiated.
In A, scanning is performed in the horizontal/vertical direction. The beam deflection/drive circuit 22C includes a bias voltage generator (hereinafter referred to as BE circuit) 203 that generates a bias voltage that biases the ion beam 21a to one side, and an ion beam 2]a.
A first beam sweeping AC power supply (hereinafter referred to as ACH circuit) 204 that scans the ion beam 21a in the horizontal direction, and a second beam sweeping AC power supply (hereinafter referred to as ACH circuit) that scans the ion beam 21a in the vertical direction.
(referred to as CV@road) 205. Also, the beam deflection/drive circuit 22C controls the beam deflector 22B based on the drive control signal S2 from the control device 24.

An ion detector 23 is an embodiment of the beam detection means 13, and is provided at one end of a wafer holder 24C on which a semiconductor substrate 25A, which is the object 15 to be irradiated, is mounted. The ion detector 23 detects the ion beam 21a irradiated onto the irradiation target 15 and outputs it to the control device 24 as an ion detection signal Sl.

24 is a control device which is an example of the control means 14;
Ion current amplifier 24A that amplifies the ion detection signal S1
, a current/positive conversion circuit 24B that converts the amplified ion detection current into an ion detection voltage, a voltage comparator 24C that compares the detection voltage with a reference voltage, which is an example of the beam reference signal SEL, and the reference voltage. A level input circuit 24D that inputs a level value related to voltage, a voltage generation circuit 24E that generates a reference voltage based on the level value, and an "abnormality" alarm when an ion detection voltage exceeding the reference voltage is detected. Abnormality alarm circuit 24F and ion generator 21. It consists of a CPO 24G that controls input and output of an acceleration and momentum analyzer 22A, a beam deflection/drive circuit 22C, and the like.

Note that 25A is a semiconductor substrate that is an example of the irradiation target 15, and is covered with a resist mask 25B formed based on design data, on which impurity diffusion layer regions of transistors and the like are formed.

In this way, according to an apparatus according to an embodiment of the invention,
Ion generator 21. A beam deflection/drive circuit 22C, an ion detector 23, a control device 24, etc. are provided, and the ion beam 21a is driven and controlled based on a preset base LjA voltage and an ion detection voltage.

That is, when the ion beam 21a is irradiated from the ion generator 21 to the semiconductor substrate 25A, the ion beam 21
a is deflected and driven by the beam deflection/drive circuit 22C. In addition, the ion beam 2 irradiated onto the semiconductor substrate 25A
1a is detected by the ion detector 23, and the beam 21
a is output to the control device 24 as an ion detection signal $1.

For this reason, the control device 24 compares the preset base 1 voltage and the ion detection voltage, and for example, the base 1 voltage set in advance is compared with the ion detection voltage. 1! When an ion detection voltage exceeding the voltage is detected, it becomes possible to drive and control the ion beam 21a so as not to irradiate the semiconductor substrate 25A.

Thereby, the conventional ion detector 23 can be used not only for the purpose of monitoring the implantation time of the ion beam 11a but also as a detection function for detecting the abnormal ion beam itself. With this, the abnormal ion beam 21a
It becomes possible to perform drive control to protect the semiconductor substrate 25A from damage.

Next, the ion implantation method according to the present invention will be explained while supplementing the operation of the apparatus.

FIG. 3 is a flowchart of an ion implantation method according to an embodiment of the present invention.

In the figure, first, in step P1, a semiconductor substrate 25A is set on a wafer holder 25C. At this time, the semiconductor substrate 25A on which the resist film 25B is formed is placed on the wafer holder 2.
5C, and the vacuum volume 820 is maintained in a vacuum state. Further, the ion beam 21a is transmitted to the ion detector 23 in advance.
is being incident on.

Next, in step P2, the semiconductor substrate 2SA is irradiated with the ion beam 21a. At this time, when the substrate 25A is centered, the beam deflection process is then started. In the deflection process, the preset reference voltage, ion implantation time, etc. are recognized by the CPU 24G, and a drive control signal S2 is output to the beam deflection/drive circuit 22C. This allows beam deflection! 22B operates, and the ion beam 21a from the ion generator 21 is irradiated and deflected onto the semiconductor substrate 25A.

Next, in step P3, the ion detector 23 is monitored and the ion beam 21a is monitored.

Here, for example, when an ion detection voltage exceeding a preset reference voltage is detected, the CPU 24C;
An abnormal state of the ion beam 21a is determined.

Further, in step P4, irradiation control processing of the ion beam 11a is performed based on the discrimination processing.

At this time, the CPU 24G outputs a drive control signal S2 for interrupting irradiation of the ion beam 21a to the beam deflection/drive circuit 22C. This drive control signal S2 is BE
A bias voltage is generated in the circuit 203, thereby forcibly changing and fixing the direction of the ion beam 21a from the semiconductor substrate 25A to the ion detector 23 via the beam deflector 201.

Note that in step P5, it is determined whether the normal ion beam is restored. At this time, if the ion beam returns to normal (Y
ES), the process moves to step P6, and the ion beam irradiation process is continued for a preset ion implantation time.

Furthermore, if the normal ion beam is not restored (No), the process moves to step P3 to continue the monitoring process, and depending on the case, an abnormality alarm is generated after a predetermined period of time has elapsed.

As a result, the resist film 25B is
Impurity ions can be implanted with good reproducibility into the semiconductor substrate 25A in areas other than the region where the ions are formed.

In this manner, according to the ion implantation method according to the embodiment of the present invention, while monitoring the ion beam 21a irradiated onto the semiconductor substrate 25A, the ion beam is 21a is performing irradiation control processing.

Therefore, an abnormal ion beam caused by charge-up of the ion generator 21 or increase in electron current is transmitted to the semiconductor substrate 2.
If there is a risk that the ion beam will be continuously irradiated with 5A, it can be determined that there is an "abnormality" by detecting a constant ion beam current. In such a case, it is possible to interrupt the irradiation of the ion beam 21a and perform the beam irradiation again when the ion beam 21a returns to normal.

This protects the resist film 25B formed on the semiconductor substrate 25A from damage caused by ion collisions in the initial stage of abnormal ion beam irradiation, and prevents physical cracks, etc., which are called mask damage, as in the conventional example. becomes possible.

〔Effect of the invention〕

As described above, the apparatus of the present invention is provided with an ion source, a beam deflection drive means, a beam detection means, and a control means, and operates an ion beam based on a preset beam reference signal and a beam detection signal. The drive can be controlled.

Therefore, when a beam detection signal exceeding a preset beam reference signal is detected by the control means, irradiation of the ion beam to the irradiation target can be interrupted.

Further, according to the method of the present invention, while monitoring the ion beam, irradiation control processing for the ion beam is performed based on processing for determining an abnormal state of the ion beam.

Therefore, if there is a risk that the target is irradiated with an abnormal ion beam continuously, it can be determined that the object is being irradiated with an abnormal ion beam. It becomes possible to protect the irradiated object.

This allows for the production of highly reliable ion implantation equipment, and
It greatly contributes to improving the production yield of highly integrated and ultra-fine semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram of an ion implantation device according to the present invention, FIG. 2 is a configuration diagram of an ion implantation device according to an embodiment of the present invention, and FIG. 3 is a diagram of an ion implantation method according to an embodiment of the present invention. FIG. 4 is a configuration diagram of a conventional ion implantation apparatus. (Explanation of symbols) 11... Ion generation source, 12... Beam deflection/driving means, 13... Beam detection means, I4... Control means, 11a... Ion beam, Sl... Beam Detection signal, SL...beam reference signal.

Claims (2)

[Claims] (1) An ion source (11) that irradiates an ion beam (11a) onto an irradiation target (15);
11a); beam detection means (13) for detecting the ion beam (11a) and outputting a beam detection signal (Si); and the ion generation source (11). A control means (14) for controlling input and output of a beam deflection driving means (12) and a beam detection means (13), the control means (14) controlling a preset beam reference signal (SL) and the beam. An ion implantation apparatus characterized in that drive control of a beam deflection drive means (12) is performed based on a detection signal (Si). (2) An ion implantation method using the ion implantation apparatus according to claim 1, wherein the ion beam (11a) irradiated to the target (15) is monitored while
An ion implantation method characterized in that an abnormal state determination process (11a) is performed, and an ion beam (11a) irradiation control process is performed based on the determination process.