JPH04177827A - Ion implantation method and device - Google Patents

Abstract

PURPOSE:To get the condition of ion implantation in accordance with the application the ion implantation area of the substance to be treated by maintaining the temperature of substance to be kept constant at a set temperature. CONSTITUTION:A disk 25 as a wafer holding part is disposed coaxially in an ion implantation chamber 21, and the disk 25 is provided with a temperature sensor 37 for detecting the temperature of the wafer 1 as the substance to be treated. And a controller 36 keeps the temperature being set according to purposes constant through a temperature adjuster 35, a cooling path 31, etc., by inputting the detection temperature of the temperature sensor 37 and feeding it back. Hereby, the temperature of the wafer can be kept constant in ion implantation at a desired value, and the ion implantation phase according to each application can be made, so crystal defects can be controlled appropriately, and in a semiconductor device, the initial electric properties can be gotten.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ion implantation method and apparatus, and in particular to a technique for improving versatility, for example, in a semiconductor manufacturing process. This invention relates to an effective technique that can be used to implant ions of impurity elements.

[Conventional technology]

In a semiconductor manufacturing process, an ion implantation method is used in which ions of an impurity element are implanted into a wafer in order to form an N shadow region or a P shadow region in the wafer. especially,
In the case where an emitter region of a bipolar transistor or a bipolar IC (semiconductor integrated circuit device) is formed, a high impurity concentration is required, so a high current ion implantation device is used.

And when a high current ion implanter is used,
The temperature of the wafer is raised by the power of the ions during ion implantation. However, this temperature increase needs to be suppressed for the following reasons.

(1) The function of the photoresist applied to the wafer as a mask for implanted ions is prevented from deteriorating due to an increase in the temperature of the wafer. For example, an increase in the temperature of the wafer causes deterioration or peeling of the photoresist.

(2) Even in processes where photoresist is not used, it is important to suppress the temperature rise of the wafer during implantation in order to eliminate implantation damage caused by ion implantation during heat treatment after ion implantation.
Common.

Therefore, conventionally, the following measures have been taken to suppress the temperature rise of the wafer during ion implantation.

(1) A so-called mechanical scanning method is employed in the wafer holding section. That is, the disk holding the group of wafers is rotated and simultaneously translated.

(2) The disk is cooled by a cooling device such as a water cooling device or an air cooling device.

Incidentally, conventionally, the temperature of the homogenized evaporator during ion implantation is generally maintained at 80"C to 100C.

An example of the ion implantation technique described is JP-A-55-24936.

[Problem to be solved by the invention]

However, in conventional ion implantation equipment,
The temperature of the wafer during ion implantation is 80°C ~
The inventor of the present invention has revealed that there is a problem in that because the temperature is maintained uniformly at a constant temperature of 100°C, it is not possible to create an ion implantation state suitable for the intended use of the ion implantation region of the wafer. .

An object of the present invention is to provide an ion implantation method and apparatus that can create an ion implantation state in the ion implantation region of a workpiece that is suitable for the intended use.

The above and other objects and novel features of the present invention will become apparent from the description herein and the attached concavities.

[Means to solve the problem]

An overview of typical inventions disclosed in this application is as follows.

That is, in an ion implantation apparatus configured to irradiate and implant ions into a workpiece held in a holding part, a temperature control device is attached to the workpiece holding part,
This temperature control device is characterized in that it is configured to keep the temperature of the object to be processed constant at a set temperature by heating or cooling the object.

[Effect]

According to the above-described means, the temperature of the object to be processed during ion implantation can be set as desired, so that, for example, when implanting impurities into a wafer, it is possible to meet the following applications. become.

(]) Set the control temperature of the sea urchin to a relatively low temperature (for example, 8
By setting the temperature to about 0° C. to 100° C., it is possible to cope with the case where the wafer is coated with photoresist or the case where the implantation layer is formed into a more perfect amorphous layer.

(2) Controlling the wafer temperature at a relatively low temperature (for example, 1
By setting the temperature to 50° C. or higher, the implanted layer can be used as a gentering layer for heavy metal contaminants.

〔Example〕

FIG. 1 is a plan sectional view showing the main parts of an ion implantation device that is an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line II-II in FIG.
3 is a schematic front view showing the entire ion implantation device, FIG. 4 is a schematic plan view,
FIGS. 5(a) and 5(b) are diagrams for explaining the action.

In this embodiment, the ion implantation apparatus according to the present invention is configured as a high current ion implantation apparatus, and is configured to implant ions as impurities into a plurality of wafers by hatching. This ion implantation device 10 includes an ion source that generates necessary ions, an ion generation system 12 that extracts an ion beam 11 from the ion source, and a separation of necessary ions from among the ions generated by the ion generation system. Mass spectrometry system 1 for
3, and X for scanning the ion beam 11 in the X-axis direction.
An axial scanning electromagnet 14 and an angle correction electromagnet 1 for correcting the angle of the ion beam lla scanned in the X-axis direction.
5, a trap 16 for trapping neutral particles,
It includes a slit 17 for passing the angle-corrected ion beam llb and an end station 18, and each part is appropriately equipped with a vacuum pump such as a Talio pump or an oil diffusion pump.

A pair of chambers 20 for forming an ion implantation chamber 21 are arranged adjacent to each other in the end station 18 . That is, each chamber 20 is formed into a substantially disk-shaped hollow body, and the ion implantation chamber 21 is configured by the hollow portion. A window 22 is provided in the chamber 20 at one location on the outer periphery of the end wall facing the slit 17, and the ion beam is incident through this window 22. Window 22 in chamber 20
A rotary shaft 2 is installed on the end wall opposite to the end wall where the
3 are inserted concentrically and rotatably supported, and the rotating shaft 23 is connected to a rotational drive device 24 such as a servo motor.
It is designed to be rotationally driven by. chamber 20
A disk 25 serving as a wafer holding portion is concentrically disposed in the ion implantation chamber 21, and the disk 25 is connected to the insertion end of the rotating shaft 23 so as to rotate integrally therewith. A wafer holder 2 is attached to the end surface of the disk 25 on the window 22 side.
6 are arranged at equal intervals in the circumferential direction on a concentric circle, and each urchin/S holder 26 is detachably attached while the wafer 1 as the object to be processed is brought into contact with the end surface of the disk 25. is configured to hold. That is, the wafer 1 is taken in and taken out of the ion implantation chamber 2I through a loading/unloading port (not shown) that is opened in the chunk\20 and configured to be sealed, and is attached to and removed from each holder 26 and exchanged. It has become so.

A temperature control device 30 is incorporated in the disk 25 as a wafer holding section. That is, disk 2
A cold/heat path 31 that substantially constitutes a part of the temperature control device 30 is opened in the body of the patient 5 in a circular ring shape, and this cold/heat path 31 effectively cools and heats the group of wafers held on the disk 23. as close as possible, and
Largely formed. A supply path 33 and a discharge path 34 for supplying and discharging a heat exchange medium 32 made of water, oil, etc. are fluidly connected to this cold/heat path 31 through a disk 25 and a rotating shaft 23, respectively. The passage 33 and the discharge passage 34 are each connected to a temperature regulator 35. The temperature regulator 35 is automatically controlled by a controller 36 consisting of a computer or the like.

On the other hand, temperature sensors 37 for detecting the temperature of wafers as objects to be processed are arranged on the disk 25 so as to detect the temperature of a group of wafers as evenly as possible. 37 is connected to input the detection results to the controller 36. By feeding back the temperature detected by the temperature sensor 37, the controller 36 maintains a constant temperature set according to the application through the temperature regulator 35, the cooling path 31, etc.

Next, the effect will be explained.

The ion beam 11 generated and extracted by the ion generation system 12 is separated into only desired ion species by the mass spectrometry system 13. The specific type of ion beam 11 is scanned in the X-axis direction by an X-axis scanning electromagnet 14, and its angle is corrected by a correction electromagnet 15. The corrected ion beam llb enters one of the ion implantation chambers 21 in the end station 18 through the window 22, and is irradiated onto the wafer 1 while being scanned in the X-axis direction. The disk 25 on which this wafer l is irradiated with the ion beam is rotationally driven through the rotation shaft 23 by the rotary drive device 24, so that the ion beam is uniformly irradiated onto the entire surface of each wafer 1 and all wafers 1. It turns out.

During this ion implantation, in the ion implantation chamber 21 to which the ion beam is not applied, the ion implanted wafer is replaced with a wafer to be ion implanted into the disk 25. This parallel processing increases the operating efficiency of the ion implantation device. That is, the ion implantation work is performed alternately for the pair of ion implantation chambers 21 and 21.

By the way, when a wafer is irradiated with an ion beam, the temperature of the wafer tends to rise due to the power of the ion beam, and if left untreated, the temperature state of the wafer becomes unstable.

However, in this embodiment, since the temperature control device 30 is incorporated into the disk 25, the temperature of the wafer can be controlled to be maintained at a desired constant temperature.

By setting a desired constant temperature according to various uses, it becomes possible to create appropriate ion implantation conditions according to various uses.

Hereinafter, an ion implantation method that is an embodiment of the present invention will be explained by explaining temperature control corresponding to a plurality of types of uses.

For example, in the following cases, the wafer temperature to be kept constant is set to a relatively low temperature of about 80°C to 100°C.

(1) When the wafer is coated with photoresist.

In this case, the photoresist applied as a mask on the surface of the wafer will deteriorate in quality and peel off due to the high temperature of the wafer, so it is necessary to prevent this deterioration in the functionality of the photoresist. Moreover, the wafer temperature is suppressed to a relatively low temperature.

(2) When it is necessary to make the ion-implanted layer a more completely amorphous layer.

When ions are implanted into a wafer at a relatively low wafer temperature, fewer crystal defects occur during ion implantation, and the crystal defects that occur are easily eliminated by annealing treatment after ion implantation. A more completely amorphous layer is obtained in the ion implantation layer.

Here, the operation of the ion implantation apparatus for maintaining the wafer temperature at a low temperature will be briefly explained.

A preselected control target temperature (for example, 80° C.) is set in the controller 36 of the temperature control device 30.

When the temperature of the Ueno X1 group held on the disk 25 rises due to the ion implantation operation described above, the temperature rise is detected by the temperature sensor 37 inside the disk 25. The temperature detected by this temperature sensor 37 is sequentially transmitted to the controller 36.

The controller 36 calculates the difference between the current ueno\ temperature sequentially transmitted from the temperature sensor 37 and the preset control target temperature, and instructs the temperature regulator 35 to perform an operation to eliminate this difference.

Based on the command from the controller 36, the temperature regulator 35
A heat exchange medium 32 such as oil is cooled, and the cooled medium 32 is supplied to the cold/heat path 31 through the supply path 33.

When the cooled medium 32 is supplied to the cooling path 31, the temperature of the disk 25 decreases, so the temperature of the Ueno\1 group held on the disk 25 decreases. The decreased wafer temperature is detected by the temperature sensor 37.

Thereafter, by repeating the above operations, the wafer temperature is maintained constant at the target temperature preset in the controller 36.

Now, in the following case, the wafer temperature to be kept constant is set to a relatively high temperature of 150''C or higher, for example.

(1) The ion-implanted layer is free from heavy metal contaminants.
When used as an interpreting layer.

When ions are implanted into a wafer at a high wafer temperature of 150° C. or higher, the wafer is placed in a situation where it is annealed, so the number of crystal defects generated during ion implantation itself is small. However, it is difficult to eliminate crystal defects that have occurred by annealing. The remaining crystal defects can then be used as a gettering layer.

Incidentally, the following areas can be considered as areas that can be used as such a gettering layer.

■　Backside area of wafer.

■ Inactive layer inside the wafer.

Since the non-active layer does not directly form an element structure, the presence of crystal defects does not pose much of a problem.

■ In a transistor structure, the emitter region after the base region is formed.

Crystal defects inside the emitter region do not directly serve as carrier lifetime killers. That is, there is no increase in leakage current or deterioration of noise characteristics. Conversely, this means that there is a gettering effect on the heavy metal substances present in the base region.

Because the gettering effect allows the crystal defects after annealing to be controlled to the desired amount, the active layer (for example, Heath) with no crystal defects can be formed.
In other words, it is possible to easily ensure the expected state in the element formation layer, especially in the active layer of minority carriers (the area on page 9 where the Hess electrons flow).

Figures 5a) and 5(b) show that in the emitter formation process of an acoustic transistor, when phosphorus (P) is implanted to form an emitter region inside the base region implanted with boron (B), These are graphs showing a comparison between the case (al) when the temperature is set at 80°C and the case (b) when it is set at 150°C. In Fig. 5, the vertical axis is the number of occurrences, and the horizontal axis is the number of occurrences. The noise voltage (V) and L indicate the standard reference line, respectively.

As shown in FIG. 5, from Example G, when the wafer temperature was controlled to 150"C, there were no cases where the noise voltage was higher than the reference line. .

Note that the specific control operations for the wafer temperature are similar to those in the previous case where the temperature was low, so a description thereof will be omitted.

According to the embodiment described above, the following effects can be obtained.

(1) By keeping the temperature of Ueno constant at the desired temperature during ion implantation, it is possible to form an ion implanted layer suitable for each application (because it is possible to
It is possible to appropriately control crystal defects and obtain desired electrical characteristics in semiconductor devices.

(2) By setting the wafer control temperature low, a completely amorphous layer can be formed in the ion-implanted layer.

(3) By setting the wafer control temperature high, the ion-implanted layer can be used as a Ge-Stalink layer of heavy metal material, so crystal defects can be controlled.

The invention made by the present inventor has been specifically explained based on Example G above, but it should be noted that the present invention is not limited to the above example and can be modified in various ways without departing from the gist thereof. Not even.

For example, the temperature control device may be configured as shown in FIGS. 6 and 7.

In FIG. 6, a recess 27 is sunk into the disc 25A, and a pad 27 made of gluecon rubber or the like is placed at the bottom of the recess 27, and the Ueno\1 comes into contact with the disc 25A through the pad 27. At the same time, it is arranged to face a temperature sensor 37.

In FIG. 7, a cold/heat pipe 31A serving as a cold/heat path is laid on the back surface of the disk 25.

Furthermore, the wafer holding section is not limited to a disk type structure, but may also be configured to have a carcell type structure, a way roller type structure, or the like.

The above explanation mainly describes the case where the invention made by the present inventor is applied to a large current ion implantation device, which is the field of application that formed the background of the invention, but is not limited thereto, such as a medium current ion implantation device, etc. It can be applied to all ion implantation techniques.

〔Effect of the invention〕

A brief explanation of the effects obtained by the representative inventions disclosed in this application is as follows.

By keeping the temperature of the wafer constant at a desired temperature during ion implantation, it is possible to form an ion implanted layer suitable for each application, so crystal defects can be appropriately controlled, making it possible to The desired electrical characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a plan sectional view showing the main parts of an ion implantation device according to an embodiment of the present invention, FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, and FIG. FIG. 4 is a schematic front view showing the whole, FIG. 4 is a schematic plan view of the opening, and FIGS. 5(a) and 5(b) are diagrams for explaining the operation. FIG. 6 is an enlarged partial sectional view showing a modification of the temperature control device;
It is. FIG. 7 is an enlarged partial sectional view showing another modification. ■...Wafer (workpiece), 10...Ion implantation device, 11, lla, llb...Ion beam, 1
2... Ion generation system, 13... Mass spectrometry system, 14.
... X-axis scanning electromagnet, 15... Angle correction electromagnet,
16...Trap, 17...Slit, 18...
End staining, 20...chamber, 21...
Ion implantation chamber, 22...window, 23...rotating shaft,
24... Rotation drive device, 25. 25A... Disk, 26... Wafer holder, 27... Recess, 28...
・Pad, 30...Temperature control device, 31...Cold heat path,
32... Heat exchange medium, 33... Supply path, 34... Discharge path, 35... Temperature regulator, 36... Controller 1. 37... Temperature sensor. Agent Patent Attorney Tatsu Kajihara Yakai 5 Figure Noyce' Densu L (V) Figure 6 Figure 7

Claims (3)

[Claims] 1. In the ion implantation method in which ions are irradiated and implanted into the workpiece, depending on the purpose of the ion implantation part of the workpiece,
An ion implantation method characterized in that the temperature of a workpiece is adjusted and maintained at a predetermined temperature. 2. In an ion implantation device configured to irradiate and implant ions into a workpiece held in a holding part, the workpiece holding part is provided with a temperature control device,
An ion implantation apparatus characterized in that the temperature control device is configured to keep the temperature of the workpiece constant at a set temperature by heating or cooling the workpiece. 3. The temperature control device includes means for heating or cooling the object holding section, a temperature sensor detecting the temperature of the object holding section, and driving the heating or cooling means based on detection by the temperature sensor. 3. The ion implantation apparatus according to claim 2, further comprising: a controller for controlling the temperature to a target temperature.