JP3371164B2 - Single wafer processing type ion implanter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-wafer processing type ion implantation apparatus equipped with a transfer means for transferring a wafer to a process chamber via a load lock chamber, and more specifically, a wafer transfer operation procedure is simplified. In addition, the present invention relates to a single-wafer processing type ion implantation apparatus equipped with a transportation means improved so as to prevent metal contamination.

[0002]

2. Description of the Related Art The transfer means of a single-wafer processing type ion implantation apparatus is roughly classified into a type in which a wafer is transferred by its own weight and a robot type. Robot type is the mainstream for the reason. As shown in FIG. 4, the conventional robot-type transfer means 50 is arranged in the process chamber B and the rotating arm 52 exposed to the atmosphere, the shuttle 54 that reciprocates between the load lock chamber A and the process chamber B, and the process chamber B. The platen (sample fixing table) 56 and the wafer table 58 are composed of independent parts.
Is located outside the load lock chamber A and is exposed to the atmosphere. The platen is a single-wafer processing end station.
It is a wafer holding plate or a wafer fixing base for holding the transferred wafer and setting the wafer at the ion implantation position. 5A is a plan view of the platen on which the wafer is horizontally mounted with the mirror surface facing upward, and FIG. 5B is a plan view of the platen.
It is a perspective view which shows the state which was inclined from the state of (a) in preparation for ion implantation. As shown in FIG. 5A, the platen 56 includes a wafer clamp that surrounds and holds the outer edge of the wafer over the entire circumference. In FIG. 4, the rotary arm 52, the shuttle 54, and the wafer stage 58 containing the wafer are provided in two systems so as to alternately operate.

[0003]

However, the conventional single-wafer processing type ion implantation apparatus provided with the robot type transportation means has the following problems. First, the transportation procedure is complicated. That is, in the above example, (1) the rotating arm 52 receives the wafer from the wafer stage 58. (2) Rotate as shown by the arrow in the figure and load lock chamber A
To the shuttle 54, and transfers the wafer to the shuttle 54. (3) The shuttle 54 advances into the process chamber B while holding the wafer horizontally with the mirror surface facing upward, and moves the wafer to the platen 5
Place horizontally on 6. (4) As shown in FIG. 5B, the platen is tilted at a predetermined angle and the mirror surface of the wafer is tilted to prepare for ion implantation.

In this way, the rotating arm 52 and the shuttle 5
4. Since the wafers are transferred between the platens 56, (1) it takes time to transfer the wafers, and as a result, the throughput (the number of wafers processed per hour) is low, and (2) the number of parts of the transfer means is large. The equipment cost increases and the number of adjustment points increases, which makes maintenance cost complicated and the cost increases. (3) Due to the large number of deliveries, the occurrence rate of accidents (wafer damage) during delivery increases accordingly. There was a problem of doing.

Secondly, in the conventional ion implantation apparatus, at the time of ion implantation, undesired metal particles are mixed into the wafer, resulting in metal contamination. When metal contamination occurs, the electrical characteristics of the semiconductor device are degraded, and the product yield of the semiconductor device is reduced. Third, when the wafer was taken in and out of the platen, the wafer collided with the wafer clamp of the platen, and the wafer was sometimes damaged.

In view of the above-mentioned problems, the present invention provides a single-wafer processing in which a single wafer is transferred to a process chamber for ion implantation, and the transfer means has a small number of wafers to be delivered and the metal contamination and wafer damage are small. Type ion implanter.

[0007]

[Means for Solving the Problems] The present inventor, after research,
The cause of metal contamination is that the ion beam causes metal particles in the metal member forming the platen to adhere to the wafer by the sputtering action as shown in FIG. 6, and the cause of the damage of the wafer is It was found that the platen has a structure, and in order to reduce the number of times of delivery, the present invention has been completed by not requiring an intermediate delivery means between the means for receiving a wafer from a wafer table and the platen. It was. Note that FIG. 6B is an enlarged view of the portion b in FIG. 6A.

In order to achieve the above object, the single-wafer processing type ion implantation apparatus according to the present invention is equipped with a transfer means for transferring a wafer from a wafer stage to a process chamber via a load lock chamber based on the above-mentioned findings. In the single-wafer processing type ion implantation apparatus, the wafer stage is provided in the load lock chamber, the wafer is received from the wafer stage provided in the load lock chamber, and the wafer is freely moved between the load lock chamber and the process chamber. To the ion implantation posture, the carrier means is constituted by a carrier also serving as a holding table for holding, and the carrier is a wafer support plate on which a wafer is placed with its mirror surface facing upward,
The wafer support plate is provided with a stopper provided at an edge portion thereof, and a tilting device for freely tilting and returning the wafer support plate so that the stopper is located downward. It is characterized by being formed of a material that is difficult to be sputtered.

In the present invention, the means for the carrier to receive the wafer to be processed from the wafer stage is the same as the conventional one, and the means for moving between the load lock chamber and the process chamber is a drive device such as an electric device on an orbit. The carriage is provided with wheels that are driven by a motor to travel. The tilting device is a combination of commonly used means, and is constituted by means as described in this embodiment, for example. Further, it is desirable to provide a cushion pad made of a soft friction material such as silicon rubber on the support plate so that the wafer does not slip easily. Examples of the material that is difficult to be sputtered by the ion beam include quartz and silicon carbide.

[0010]

In the present invention, the wafer table is provided in the load lock chamber, the transfer means receives the wafer from the wafer table provided in the load lock chamber, and is movable between the load lock chamber and the process chamber. Further, by configuring the wafer as a carrier that also serves as a holder for shifting and holding the wafer to the ion implantation posture, a single carrier that also serves as a holder can perform the operations of the conventional rotating arm, shuttle, and platen.
As a result, the number of wafer deliveries required when processing one wafer with the ion implantation apparatus is significantly reduced. Further, by forming the portion of the carrier that comes into contact with the wafer with a material that is difficult to be sputtered by the ion beam, metal contamination can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in more detail based on embodiments with reference to the accompanying drawings. FIG. 1 is a schematic layout view showing the configuration of an embodiment of a single-wafer processing type ion implantation apparatus according to the present invention, FIG. 2 (a) is a side view of a carrier which also serves as a wafer holder, and FIG. 2 (b) is The lower part of the support plate is omitted in the plan view. The single-wafer processing type ion implantation apparatus (hereinafter simply referred to as an apparatus) 10 of the present embodiment includes a load lock chamber 1
2 and the process chamber 14. Load lock room 1
Reference numeral 2 denotes a vacuum chamber for taking in and taking out wafers without opening the process chamber 14 to the atmosphere, which is constantly maintained at a vacuum by a vacuum suction facility (not shown). The process chamber B is a region where ions are implanted into the wafer. In FIG. 1, a load lock chamber 12 and a process chamber 14
In both cases, the area is schematically shown by a broken line.

In the load lock chamber 12, a wafer table 16 having the same structure as the conventional one is arranged. Wafer table 16
7B is a magazine-type wafer rack that can be vertically moved up and down. As shown in FIG. 7B, a wafer 17 is horizontally held by a shelf portion 17 that horizontally protrudes from a vertical wall of the wafer stage main body. A track 20 is laid between the load lock chamber 12 and the process chamber 14, on which a carrier 18 also serving as a wafer holder (hereinafter, simply referred to as a carrier) travels to run. It can be freely moved between 12 and the process chamber 14. In this embodiment, in order to improve the throughput of wafer processing, the wafer table 16
There are two systems of the carrier 18 and the carrier 18, and the wafers are alternately carried from the load lock chamber A to the process chamber B for processing.

As shown in FIGS. 2A and 2B, the carrier 18 includes a support plate 22, a tilting device 24 for tilting and returning the support plate 22, and a carriage 26 for mounting them. It is configured. The support plate 22 is shown in FIG.
As shown in (b), it is a bifurcated plate member composed of two strip-shaped arms 28, 28 and a base 30, and a wafer W (indicated by an imaginary line) with a mirror surface facing upward has two peripheral edge portions. It is formed so as to be held by book arms 28, 28 and a base 30. Small cylindrical stoppers 32, 32 are provided near both ends of the base portion 30 of the support plate 22 so as to project from the support plate 22, and the size thereof is, for example, 5 mm in height.
mm, diameter 5 mm. Even if the support plate 22 is inclined, the outer edge of the wafer W is supported by the stoppers 32 and 32 at two points, so that the wafer W does not slide down. Further arm 28
The cushion pad 3 made of silicon rubber is used to improve the familiarity with the wafer and to improve the wafer holding property.
4 is in place. The size of the pad 34 is, for example, about 1 mm in diameter. The portion in contact with the wafer W, that is, the support plate 22 and the stopper 32 are made of quartz so as not to be sputtered by the ion beam.

The tilting device 24 includes a front support leg 36 for supporting the stopper side of the support plate 22, that is, the base 30, a rear support leg 38, 38 for supporting each arm 28, 28 of the support plate 22, and an actuator. And 40. The front support leg 36 is composed of a small-diameter leg 42 and a large-diameter leg 44 below it, and the small-diameter leg 42 is telescopically moved into and out of the large-diameter leg 44 by the operation of the actuator 40. It is flexible. The front support leg 36 is rotatably supported at its upper end via a shaft 46.
And is fixed to the carriage 26 at the lower end. The actuator 40 is a known device such as a fluid pressure drive device such as a hydraulic cylinder or a pneumatic cylinder, or an electric motor, and is connected to the small diameter leg 42 and connected to the small diameter leg 42.
Is driven to move in and out of the large-diameter leg 44. The rear support legs 38 are rotatably connected at their upper ends via shafts 48 to the vicinity of the tips of the arms 28 of the support plate 22, and are fixed on the carriage 26 at their lower ends. The tilting device 24 is not limited to this.
Alternatively, the rotary drive of the electric motor may be converted into a telescopic movement of the support leg by a combination of a pinion and a rack.

With the above configuration, FIGS. 3 (a) and 3 (b)
As shown in FIG. 4, when the front support leg 36 is contracted, the base portion 30 of the support plate 22 descends with respect to the tip of the arm 28, and the support plate 22 can be tilted at a desired angle. vice versa,
As shown in FIG. 2A, when the front support leg 36 is extended, the base portion 30 rises and the support plate 22 becomes horizontal.

The carriage 26 is shown in FIGS. 2 (a) and 2 (b).
As shown in FIG. 5, the vehicle body 50, four wheels 52 provided on the front, rear, left, and right sides of the vehicle body 50 to run on the track 20 while supporting the vehicle body 50, and a drive device 54 for driving the vehicle wheels 52. ing. The drive device 54 is a commonly used device such as an electric motor. The carrier 18 is provided with a known automatic operation device (not shown), which allows the tilting device 24 to operate.
Also, the carriage 26 is automatically operated by remote control.

Next, the operation of the apparatus 10 will be described with reference to FIGS. The carrier 18 receives the wafer from the wafer stage 16 in the load-lock chamber 12 by the same means as the conventional one while the support plate 22 is horizontal, holds the wafer, and travels on the track 20 to enter the process chamber 14. To do. Carrier 1
8 receives the wafer from the wafer stage 16 as shown in FIG.
This is shown in FIGS. 8 and 9. 7, 8 and 9,
(A) is a schematic diagram seen from the side surface of the wafer, and (b) is a schematic diagram seen from the front side of the wafer table.

The carrier 18 is, as shown in FIG.
The wafer table 16 is approached, and the arm 28 of the carrier 18 is inserted under the wafer W of the wafer table 16 as shown in FIG. 7B. Next, as shown in FIG. 8B, the wafer stage 16 descends about 1/3 of the distance between the wafers W,
The wafer W is placed horizontally on the arm 28 of the carrier 18.
Then, the carrier 18 with the wafer W placed thereon is shown in FIG.
As shown in (a), it is separated from the wafer stage 16. Next, when the carrier 18 is completely separated from the wafer stage 16 as shown in FIG. 9A, the wafer stage 16 once rises upward by about 1/3 of the distance between the wafers W and the original state. After returning to the position, the wafer W is then lowered downward by the distance between the wafers W, and the next wafer W is positioned at the height position of the carrier 18, as shown in FIG. 9B.

While moving on the track 20 while receiving and holding the wafer, the carrier 18 is moved as shown in FIG.
The front support leg 36 is contracted, the support plate 22 is inclined at an angle α with respect to the horizontal, and the wafer W is held obliquely. The wafer W is held by the stopper 32 and does not slip off. In this example, α is about 30 °.
Next, when the carrier 18 reaches the ion implantation position in the process chamber 14, it stops there. Then, the carrier 18
Causes the front support leg 36 to further contract to tilt the support plate 22 to the channeling suppression angle (about 83 ° at β in the figure). As a result, the wafer W completes the preparation for the ion implantation process. In the present apparatus 10, the wafer stage 16 and the carrier 1
There are 2 systems of 8 and 8 and they are operated alternately.
By performing the above operation in reverse, the wafer W subjected to the ion implantation process is returned to a desired position, for example, the wafer stage 16. Further, the carrier 18 can be made to stand by at a proper position in order to determine the ion implantation rotation angle.

With the above structure, when processing one wafer, the wafer is not delivered during the transfer, and the transfer means of the present apparatus 10 has a simpler structure than the conventional transfer means. The number of parts has also decreased significantly. The support plate 22 does not cover the periphery of the wafer as in the conventional wafer fixing base, but is configured to simply mount the wafer with the mirror surface facing upward, and all the contacting portions of the wafer are made of non-metal. Therefore, damage such as chipping and chipping of the wafer is small, and metal contamination at the time of ion implantation is suppressed.

[0021]

According to the present invention, in the single-wafer processing type ion implantation apparatus, the wafer stage is provided in the load lock chamber, and the transfer means receives the wafer from the wafer stage provided in the load lock chamber and the load lock chamber. The wafer is moved from the wafer table to the process chamber when the ion implantation process is performed on the wafer by configuring the carrier that also moves and holds the wafer to the ion implantation posture and holds and holds the wafer. There is no need to hand over the wafer during transportation.
Therefore, the time required for wafer delivery is reduced, and the throughput of wafer ion implantation processing is improved. Further, as compared with the conventional device, the structure is simple and the number of parts is greatly reduced, so that the facility cost and the maintenance and inspection cost are reduced, and the parts adjustment is easy. Further, the damage occurrence rate of the wafer, which has occurred during the delivery of the wafer, is reduced by that much. Further, by forming the portion of the carrier that comes into contact with the wafer with a material that is difficult to be sputtered by the ion beam, it is possible to prevent metal contamination. Further, the wafer support plate of the carrier has a planar structure to prevent the wafer from being damaged when the wafer is delivered.

[Brief description of drawings]

FIG. 1 is a schematic layout diagram showing a configuration of an embodiment of a single-wafer processing type ion implantation apparatus according to the present invention.

FIG. 2A is a side view of a carrier that also serves as a wafer holder, and FIG. 2B is a plan view thereof, in which a lower portion of a support plate is omitted.

3A and 3B are explanatory views showing the inclination of the support plate during wafer transfer and the inclination of the support plate during the ion implantation process, respectively.

FIG. 4 is a schematic layout diagram showing an example of a conveying unit of a conventional single-wafer processing type ion implantation apparatus.

5A and 5B are a plan view and a perspective view of a conventional wafer fixing base, respectively.

6 (a) is a schematic diagram for explaining the principle of occurrence of metal contamination, and FIG. 6 (b) is an enlarged view of portion b of FIG. 6 (a).

FIG. 7A is a schematic view of a state in which a carrier approaches a wafer in a wafer table, viewed from the side of the wafer, and FIG.
FIG. 7B is a schematic view of the same state viewed from the front side of the wafer table.

FIG. 8A is a schematic view of a state in which a carrier is separated from a wafer table viewed from the side surface of the wafer, and FIG. 8B is a schematic view viewed from the front surface of the wafer table.

9A is a schematic view of a state where the carrier on which the wafer is placed is separated from the wafer table, as viewed from the side surface of the wafer, and FIG.
FIG. 6B is a schematic view of the wafer stage lowered by one stage from the front side of the wafer stage.

[Explanation of symbols]

10 One Example of Single Wafer Processing Ion Implanter According to the Present Invention 12 Load Lock Chamber 14 Process Chamber 16 Wafer Stage 17 Wafer Stage Shelf 18 Wafer Holding / Carrier 20 Track 22 Support Plate 24 Tilt Device 26 Carriage 28 Belt-shaped arm 30 Base 32 Stopper 34 Cushion pad 36 Front support leg 38 Rear support leg 40 Actuator 42 Small diameter leg 44 Large diameter leg 46, 48 Shaft 50 Vehicle body 52 Wheel 54 Drive device

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Claims (2)

(57) [Claims] 1. A single-wafer processing type ion implantation apparatus comprising a transfer means for transferring a wafer from a wafer stage to a process chamber via a load lock chamber, wherein the wafer stage is provided in the load lock chamber and provided in the load lock chamber. The transfer means is configured by a transfer body that also serves as a holding table that receives the wafer from the wafer table and freely moves between the load lock chamber and the process chamber, and shifts and holds the wafer to the ion implantation posture. The carrier has a wafer support plate on which a wafer is placed with its mirror surface facing upward, a stopper provided at an edge of the wafer support plate, and the wafer support plate is freely tilted so that the stopper is on the lower side, and A single-wafer processing type Io characterized by having a tilting device for returning, and a carrier portion that comes into contact with the wafer is formed of a material which is difficult to be sputtered by an ion beam. Injection device. 2. The single-wafer processing type ion implantation apparatus according to claim 1, wherein a portion of the carrier that comes into contact with the wafer is made of quartz or silicon carbide.