JPH08138614A - Ion implantation device - Google Patents

Abstract

PURPOSE: To detect whether a wafer is rightly held in a prescribed holding region prescribed on a wafer holding face to prevent beforehand production of defectives in ion implantation processing. CONSTITUTION: An ion implantation device is provided with a wafer holding board 30 provided with an ion detection sensor and an alarm device which receives a signal from the ion detection sensor and issues an alarm. Four ion detection sensors 34A-D are arranged at the same interval on an arrangement limit line (L) provided along the outer edge of a prescribed holding region (S) in the wafer holding face 32 of the wafer holding board. Respective lead wires of the ion detection sensors are connected to the alarm device through penetration holes 36A-D penetrating through the wafer holding board. When one part of an outer edge is in the outside of the arrangement limit line, namely, a wafer receives ion irradiation in a position deviation state, the wafer (W) cannot obstruct all the ion beam so that corresponding ion detection sensors detect incidence of the ion beam. The ion detection sensors send a signal of detecting position deviation of the wafer to the alarm device so that the alarm device issues an alarm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion implantation apparatus, and more particularly, when performing ion implantation on a wafer, in order to prevent defective portions of the ion implantation from occurring in the wafer,
The present invention relates to an ion implantation apparatus capable of confirming whether a wafer is held so as to overlap a predetermined holding area.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, an ion implanter is often used to implant impurity ions into a substrate. As shown in FIG. 3, the ion implanter of the conventional ion implanter takes out the wafers W one by one from the cassette C1 and delivers the wafers W to the wafer holding board 14.
And the wafer W slid down from the take-out device 12
Wafer holding plate 14 for holding the wafer W on the wafer holding surface, a delivery device 16 for receiving the ion-implanted wafer W from the wafer holding plate 14 and delivering it to the cassette C2, and the wafer holding plate 14 in the arrow direction. A rotation mechanism (not shown) for rotating the wafer holding chamber 14 and a chamber 18 for housing the wafer holding plate 14 are provided.

As shown in FIG. 4, the wafer holding plate 14 is
A wafer holding surface 20 for holding a wafer is provided on one surface, which is formed of a rectangular member, and the wafer is held on the surface by a conventional mechanism such as a chuck. The wafer holding plate 14 is rotated by a rotating mechanism (not shown) to remove the take-out device 12.
When receiving a wafer that slides obliquely downward from the wafer holding surface 20, the wafer holding surface 20 is slid down, and during ion implantation, the wafer holding surface 2 extends in a direction orthogonal to the ion irradiation direction.
0 is raised and the ion-implanted wafer is sent out.
The wafer holding surface 20 is moved along the delivery direction.

As shown in FIGS. 5 (a) and 5 (b),
The wafer holding surface 20 defines a predetermined holding area S (a hatched area) in which the wafer is to be placed so as to overlap the area. As shown in FIG. 5A, when the wafer is held so as to overlap the predetermined holding area S, good ion implantation can be uniformly performed over the entire surface of the wafer. On the other hand, as shown in FIG. 5B, if a part of the wafer W '(a region hatched by a horizontal line) is out of the predetermined holding area S, the part W'is not ion-implanted.
Alternatively, the defective portion has an insufficient ion implantation amount.

As shown in FIG. 4, the wafer holding surface 20 is provided with a plurality of protruding stoppers 22 along the outer edge of the predetermined holding area S and along the tangent line of the outer edge. The stoppers 22 are arranged on the vertices of the isosceles triangle and on the isosceles side with the falling direction of the wafer as the center line, and correctly hold the wafer that slides obliquely downward from the take-out device 12 in the predetermined holding area S.
And is positioned so as to overlap the predetermined holding area S. In general, the wafer is positioned so that its orientation flat (commonly known as an orientation flat) is located below.

[0006]

However, originally, the wafer should be held in the predetermined holding area S as shown in FIG. 5 (a). However, in the above-mentioned conventional ion implantation apparatus, the wafer can be held for various reasons. The guide and positioning functions of the stopper 22 of the holding plate 14 are not as good as expected, and the wafer deviates from the predetermined holding area S and is held on the wafer holding surface 20 in a position shift state as shown in FIG. 5B. Was often done. Therefore, it is difficult to perform uniform ion implantation over the entire surface of the wafer, and for example, there is a problem that a portion where the amount of ion implantation is insufficient or a portion where ions are not implanted occurs, resulting in a reduction in product yield.

Therefore, an object of the present invention is to detect whether or not a wafer is correctly held in a predetermined holding area defined on the wafer holding surface, and to prevent the occurrence of defective products in the ion implantation process. It is to provide a device.

[0008]

In order to achieve the above object, an ion implantation apparatus according to the present invention is provided with a wafer holding plate in which a predetermined holding area is defined on a wafer holding surface, so that it overlaps with the predetermined holding area. Ion implantation equipment that accepts wafers and holds them in place while performing ion implantation, holds a prescribed amount of misalignment allowable distance that is defined as the wafer misalignment distance that can be tolerated to maintain in-plane uniformity during ion implantation. It is characterized in that the wafer placement limit line is drawn inward from the outer edge of the area and along the outer edge into a predetermined holding area, and a plurality of ion detection sensors are provided on the placement limit line.

The term “positional deviation allowable distance” as used in the present invention means a wafer positional deviation distance which is allowable for maintaining the in-plane uniformity during ion implantation, and is determined by experiments using an actual machine at different distances depending on the ion implantation apparatus. be able to. In addition, the placement limit line drawn inward from the outer edge of the predetermined holding area by the allowable displacement distance is such that a part of the outer edge of the wafer exceeds the placement limit line, that is, the misalignment tolerance is allowed from the outer edge of the predetermined holding area. A portion of the wafer that is located inside the predetermined holding area at a distance greater than or equal to the distance, and is a line drawn so that a portion of the wafer opposite to a part of the outer edge thereof deviates from the predetermined holding area. The ion detection sensor used in the present invention is a known ion detection sensor. Further, the detection signal of the ion detection sensor may be input to an alarm device to issue an alarm, and further input to a stop device to stop the ion implantation device.

[0010]

According to the present invention, the ion detection sensor is provided on the arrangement limit line which is located inside the outer edge of the predetermined holding area defined on the wafer holding surface by the positional deviation allowable distance.
If the wafer is located outside the placement limit line over the entire circumference of the outer edge of the wafer, the wafer blocks all the ion beams reaching the ion detection sensor, and the ion detection sensor cannot detect the ion beam. Therefore, when the ion detection sensor does not detect the ion beam, it can be confirmed that the wafer is located within the predetermined holding area. On the other hand, if a part of the wafer is out of alignment with the predetermined holding area and is misaligned, the wafer cannot block the entire ion beam reaching the ion detection sensor, so the ion detection sensor does not block the ion beam. The ion beam that has not been detected is detected. Therefore, when the ion detection sensor detects the ion beam, it can be determined that a part of the wafer is out of position from the predetermined holding area. By the same action principle, it is possible to detect a crack in the wafer that occurs when the wafer is transferred from the cassette to the wafer holding plate by the device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings. FIG. 1A and FIG.
1B is a plan view of a wafer holding plate of the ion implantation apparatus according to the present invention and a cross-sectional view taken along line XX ′ in FIG. 1A. The ion implantation apparatus of the present embodiment includes a wafer holding plate 30 having an ion detection sensor instead of the wafer holding plate shown in FIG. 4 and an alarm device (not shown) that receives a signal from the ion detection sensor and issues an alarm. I have it.

As shown in FIGS. 1 (a) and 1 (b),
On the wafer holding surface 32 of the wafer holding plate 30 provided in the ion implantation apparatus of the present embodiment, on the arrangement limit line L provided inside the outer edge of the predetermined holding area S by the positional deviation allowable distance and along the outer edge thereof. Four ion detection sensors 34A at equal intervals
~ D are provided. As an ion detection sensor, for example, 0
A Model 000 ion detection sensor manufactured by 0 can be used. Through holes 36 through which lead wires (not shown) of the ion detection sensors 34A to 34D penetrate the wafer holding plate 30.
It is connected to the alarm device through A to D. In the present embodiment, which is an ion implanter for a 4-inch wafer, the placement limit line L is 20 from the outer edge along the outer edge of the predetermined holding area of the wafer.
It's just inside the mm.

With the above structure, as shown in FIG. 2A, the wafer W is located outside the placement limit line L where the ion detection sensors 34A to 34D are placed over the entire circumference of the outer edge thereof. When the wafer W receives the ion irradiation, the wafer W blocks the ion beam, and thus the ion detection sensors 34A to 34D are used.
Does not detect the incidence of an ion beam. On the other hand, FIG. 2 (b)
As shown in FIG. 5, a part of the outer edge of the wafer W is located outside the placement limit line L, that is, a part of the wafer W is located outside the predetermined holding area S, and uniform ion implantation is performed on the wafer. When ion irradiation is performed in a state where the entire surface of W cannot be applied, the wafer W cannot block all of the ion beam, so that the corresponding ion detection sensors 34A and 34B detect the incidence of the ion beam. Then
The ion detection sensors 34A and 34B send a signal indicating that an ion beam has been detected to an alarm device, and the alarm device issues an alarm. Further, the alarm device can issue an emergency stop signal to the ion implantation part as needed to check and repair the defect of the ion implantation part.

[0014]

According to the present invention, in an ion implantation apparatus in which a wafer is received so as to overlap with a predetermined holding area and ion implantation is performed while holding the wafer, the position shift allowable distance is from the outer edge of the predetermined holding area. The wafer is held in a predetermined position when the ion detection sensor detects the ion beam by entering the inside and drawing the placement limit line along the outer edge into the predetermined holding area, and providing multiple ion detection sensors on the placement limit line. It is detected that the wafer is not held in the area, that is, the wafer is held in a state where uniform ion implantation cannot be performed over the entire surface of the wafer. By using the ion implantation apparatus according to the present invention, it is possible to prevent the situation where the in-plane uniformity of ion implantation cannot be maintained due to the displacement of the wafer. Further, it is possible to detect the cracking of the wafer, which often occurs when the wafer is received from the cassette to the wafer holding plate. Therefore, the ion implantation apparatus according to the present invention can improve the yield of the ion implantation process.

[Brief description of drawings]

1A and 1B are a plan view of a wafer holding plate of an ion implantation apparatus according to the present invention and FIG. 1A, respectively.
FIG. 9 is a sectional view taken along line XX ′ in FIG.

FIG. 2A and FIG. 2B are diagrams for explaining the operation of the ion detection sensor.

FIG. 3 is a schematic cross-sectional view showing a configuration of an ion implantation part of the ion implantation device.

FIG. 4 is a plan view of a wafer holding plate provided in a conventional ion implantation apparatus.

5 (a) and 5 (b) are views for explaining the arrangement of wafers held on a wafer holding plate, respectively.

[Explanation of symbols]

12 take-out device 14 wafer holding plate 16 delivery device 18 chamber 20 wafer holding surface 22 stopper 30 wafer holding plate provided in the ion implantation apparatus according to the present invention 32 wafer holding surface 34 ion detection sensor 36 through holes C1, C2 cassette S predetermined Holding area L Placement limit line W Wafer

Claims (1)

[Claims] 1. An ion implantation apparatus, comprising a wafer holding plate having a predetermined holding area defined on a wafer holding surface, receiving a wafer so as to overlap the predetermined holding area, and performing ion implantation while holding the wafer. When the ion implantation is performed, the wafer's placement limit line is held inward from the outer edge of the predetermined holding area and the wafer's placement limit line is held for a predetermined distance by the allowable misalignment distance defined as the wafer's misalignment distance that is allowable to maintain in-plane uniformity. An ion implantation apparatus, wherein a line is drawn in the area and a plurality of ion detection sensors are provided on the line of the arrangement limit.