JP2000173530A - Ion implantation device and ion implantation detecting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy to find an inferior wafer by detecting the state of a wafer before ion implantation and after the ion implantation and by judging whether the ion implantation is rightly implemented based on the respective states of the wafer before and after the ion implantation. SOLUTION: A wafer 4a or 4b before ion implantation is carried in a load lock chamber 2a or 2b in an ion implantation device, light is radiated thereto by an optical sensor 7 in its mounted on a wafer receiving mount 9, and the reflected light is measured. Secondly, the wafer 4a, or 4b is put in a process chamber and after completing implantation, the wafer is carried outside via the load lock chamber 2a or 2d. In this case, light is radiated to the wafer 4a, or 4b again by the optical sensor 7. The reflecting light is slightly changed from that before implantation because of the damage to the wafer surface by the beam ion. The signal values before and after the implantation are compared by a comparator and if the difference is a prescribed reference value or less, an error alarm is issued to show non-implantation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ion implantation apparatus and an ion implantation detection method.

[0002]

2. Description of the Related Art As is well known, a semiconductor device manufacturing process includes an ion implantation process. This ion implantation step is a step of forming a p-type region or an n-type region in a semiconductor by implanting impurities into the semiconductor.

[0003] In this ion implantation step, impurity doping for controlling the characteristics of the transistor is performed, so that the influence on the characteristics of the product is extremely large.

Conventionally, abnormalities in threshold voltage characteristics may occur in the process of checking the characteristics of a product. In this case, only one or two of a plurality of wafers in a lot may have different characteristic values. In many cases, such a situation can be presumed to be due only to the non-implantation or the double implantation in the ion implantation process.

[0005] By the way, there are a batch-type ion implantation apparatus and a sheet-type ion implantation apparatus. However, in the case of a batch-type ion implantation apparatus, even if the characteristic becomes abnormal, it can occur only for the number of batches. It is not considered that such a problem occurs. On the other hand, a single-wafer ion implantation apparatus, as the name implies, is processed one by one, which may be the cause of the cause. There was a problem.

FIG. 4 is a sectional view for explaining the operation of the platen in the ion implantation apparatus.

Conventionally, in an ion implantation apparatus, the dose amount is set to 1
The counting is performed for each wafer, and the implantation of the set dose is completed, and it is determined that the wafer 4 has been implanted.

Further, as shown in FIG. 4, the platen 5 holding the wafer 4 is in a horizontal direction during transfer and is in a vertical direction during ion implantation. As shown in FIG. 4, when the platen 5 is in the vertical direction, the beam 6 is irradiated and ion implantation is performed. When the injection is completed, the operation to return to the horizontal direction is performed.

However, during the implantation operation, electrical disturbance occurs due to the discharge of the ion implantation apparatus itself, and the above operation is not normally processed, and the ion implantation apparatus is carried out without being implanted. It is conceivable that the operator determines that the wafer has not been implanted and implants the wafer again by implanting the wafer again.

[0010]

In the above-described situation, it has not been possible to detect the presence or absence of ion implantation into a wafer. Therefore, a defect is found for the first time in an operation check process after the product is completed. And it is impossible to quickly find a defect.

Conventionally, it is difficult to determine at which point a product defect has occurred, which is an obstacle to improving the yield.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to improve the accuracy of finding a single wafer defect by reliably and quickly detecting the presence or absence of ion implantation. It is an object of the present invention to provide an ion implantation apparatus capable of improving the yield.

[0013]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a sensor for detecting the state of a wafer to be ion-implanted, the state of the wafer before the ion-implantation processing and the state after the ion-implantation processing by the sensor. Control to detect whether the ion implantation process has been correctly performed based on the state of the wafer before the ion implantation process and the state of the wafer after the ion implantation process detected by the sensor. And an ion implantation detecting apparatus.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view of an end station section in an embodiment of an ion implantation apparatus according to the present invention.

An end station for performing an implantation operation in the ion implantation apparatus is a process chamber (injection processing chamber).
1 and a load lock chamber 2a and a load lock chamber 2b.

The ion implantation apparatus according to the present embodiment
Processing wafers one by one, wafer type (serial type)
It is an ion implantation apparatus.

As shown in FIG. 1, the wafer 4a is transferred from the outside on the atmosphere side to the process chamber 1 maintained at a high vacuum of about 10 ^-7 Torr, and is subjected to an implantation process.

At this time, if the process chamber 1 is directly connected to the atmosphere side, the state inside the process chamber 1 will be alternately repeated at atmospheric pressure and high vacuum every time a wafer is transferred. Since it occupies a large space volume, it takes an enormous amount of time, and invites ingress of dust, which is not very practical in the production of semiconductor devices.

For this reason, a small-volume load lock chamber maintained at a medium vacuum of about 10 ⁻⁵ Torr is provided, and functions as a buffer chamber between the outside and the process chamber.

In FIG. 1, two load lock chambers 2a and 2b are provided for the purpose of improving the throughput, and one of the load lock chambers is processed while processing the wafer in the other load lock chamber. Prepare wafers in load lock chamber. The wafer leaves the incoming load lock again. That is, in FIG.
While processing the wafer 4a conveyed through a, the wafer 4b is prepared in the other load lock chamber 2b.

In FIG. 1, 3a and 3b are flap valves, 5 is a platen, and 6 is a beam.

FIG. 2 shows the load lock chamber 2a shown in FIG.
FIG. 4 is a schematic diagram showing the internal structure of the first and second embodiments.

As shown in FIG. 2, the load lock chamber 2
Each of a and 2b is provided with a wafer pedestal 9 for receiving the wafer 4a or 4b from the transfer arm 8, and a sensor 7 is provided on the upper surfaces of the load lock chambers 2a and 2b. In the present embodiment, an optical sensor is used as the sensor 7.

Next, the operation of this embodiment will be described.

FIG. 3 is a flowchart for explaining the operation of the embodiment shown in FIG.

The wafer 4a or 4b before the ion implantation is carried into the load lock chamber 2a or 2b, and when it is placed on the wafer pedestal 9, light is applied to the wafer by the optical sensor 7, and the reflected light is measured. Store the value (F-
1).

Next, the wafer 4a or 4b enters the process chamber 1 and is subjected to an implantation process. At this time, the wafer surface is hit by beam ions and is damaged (F-2).

After the completion of the implantation process, the wafer 4a or 4b
Is transported to the outside again through the load lock chamber 2a or 2b, but when entering the load lock chamber 2a or 2b, the optical sensor 7 is again applied to the wafer 4a or 4b. Due to the damage on the wafer surface, the reflected light slightly changes from before the injection. Read the signal value (F
-3), as shown in step (F-4), the signal value before injection and the signal value after injection are compared by a comparator, and if the difference is equal to or more than a predetermined reference value, injection is completed (F- 5)
Continue processing. If the value is less than the predetermined reference value, an error is warned as non-injection (F-6), and the conveyance is stopped.

Next, another embodiment of the ion implantation apparatus according to the present invention will be described.

In this embodiment, a temperature sensor is provided instead of the optical sensor 7 shown in FIG. 2, and the state of the wafer before and after ion implantation is detected by the temperature sensor.

The wafer receives the beam current at the time of ion implantation and rises in temperature by receiving power. The degree of the temperature rise changes according to the magnitude of the beam current and the acceleration voltage.

For this reason, the wafer is held by the platen 5 and ion-implanted.
Is provided with a cooling mechanism such as pure water, florinate or gas, and the wafer is cooled from the back surface. Even if such cooling is performed, when the beam power is large, the temperature of the wafer rises to about 100 ° C.

When the wafer is transferred from the process chamber 1 to the load lock chamber 2a or 2b, the transfer is performed in a vacuum and the transfer time is only several seconds. Very few.

Therefore, in the present embodiment, the sensors installed in the load lock chambers 2a and 2b are temperature sensors, and the temperature before injection is compared with the temperature after injection to confirm whether or not injection has been completed. .

[0036]

As described above, according to the present invention,
Since the information of the ion implantation processing is directly obtained for the wafer itself, the accuracy of finding one defect is improved, and the effect of preventing one defect can be expected.

Further, according to the present invention, the presence or absence of ion implantation can be reliably and promptly detected, and the yield of semiconductor devices can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an end station section in an embodiment of an ion implantation apparatus according to the present invention.

FIG. 2 is a schematic diagram showing an internal structure of the load lock chamber shown in FIG.

FIG. 3 is a flowchart illustrating an operation of the exemplary embodiment shown in FIG. 2;

FIG. 4 is a cross-sectional view illustrating an operation of a platen in the ion implantation apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Process chamber 2a, 2b Load lock chamber 3a, 3b Flap valve 4, 4a, 4b Wafer 5 Platen 6 Beam 7 Sensor 8 Transfer arm 9 Wafer support

Claims (10)

[Claims] 1. A sensor for detecting a state of a wafer to be subjected to ion implantation, a state of a wafer before ion implantation and a state of a wafer after ion implantation are detected by the sensor, and the ion implantation detected by the sensor. An ion implantation detection apparatus comprising: a control unit that determines whether or not the ion implantation processing has been correctly performed based on a state of the wafer before the processing and a state of the wafer after the ion implantation processing. 2. The ion implantation process according to claim 1, wherein the difference between a state of the wafer before the ion implantation process detected by the sensor and a state of the wafer after the ion implantation process is equal to or larger than a predetermined reference value. The ion implantation detection apparatus according to claim 1, wherein it is determined that the ion implantation has been correctly performed. 3. The ion implantation detection apparatus according to claim 1, wherein the sensor is an optical sensor that detects light reflected by the wafer. 4. The ion implantation detecting apparatus according to claim 1, wherein the sensor is a temperature sensor for detecting a temperature of the wafer. 5. An ion implantation apparatus comprising the ion implantation detection apparatus according to claim 1. Description: 6. The ion implantation apparatus according to claim 5, wherein the ion implantation is performed in a single wafer mode. 7. A state of a wafer to be ion-implanted is detected before and after the ion implantation processing, and the ion implantation processing is performed based on a state of the wafer before the ion implantation processing and a state of the wafer after the ion implantation processing. An ion implantation detection method, comprising: determining whether or not the ion implantation has been correctly performed. 8. When the difference between the state of the wafer before the ion implantation processing and the state of the wafer after the ion implantation processing is equal to or larger than a predetermined reference value, it is determined that the ion implantation processing has been correctly performed. The ion implantation detection method according to claim 7, wherein: 9. The method according to claim 7, wherein the state of the wafer is light reflected by the wafer. 10. The ion implantation detection method according to claim 7, wherein the state of the wafer is a temperature of the wafer.