JP2005149944A - Ion injection device and method for fabricating semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ion injection device injecting ions while controlling an affection resulting from channeling for each substrate to be treated by measuring a surface direction for each substrate. <P>SOLUTION: The ion injection device injecting impure ions into a silicon wafer 2 has a platen 1 supporting the wafer 2, a goniometer moving the platen 1, an X-ray irradiation mechanism 3 irradiating X-rays to the wafer 2 supported by the platen 1, and a scintillation counter 6 detecting a reflected X-ray 5 which is an X-ray 4 irradiated from the mechanism 3 and reflected from the wafer 2. The ion injection device further has: an ion source 7 ionizing an impure gas; a mass analyzer 8 extracting the impure ions to be injected into the wafer 2 among ionized impure ions; an acceleration tube 9 accelerating the extracted impure ions; and a lens 10 forming the accelerated impure ions in a desired beam shape. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ion implantation apparatus and a method for manufacturing a semiconductor device, and more particularly, an ion implantation apparatus that performs ion implantation while controlling the influence of channeling for each substrate to be processed by measuring a plane orientation for each substrate to be processed. And a method of manufacturing a semiconductor device.

Hereinafter, a method for ion implantation using a conventional ion implantation apparatus will be described.
First, an impurity gas is ionized in an ion source, and the ionized impurity is extracted by an extraction electrode. The extracted impurity ions are drawn into a mass analyzer using an analysis electromagnet or the like, and the impurity ions to be implanted into the silicon wafer are extracted in the mass analyzer. Incidentally, the mass analyzer, typically an ion source in the example ⁴⁹ BF ₂ ^{+, 11} B ^{+, 10} since B ⁺ multiple types of ions, such as occurs, ions implanted in the wafer of these ions (e.g., ¹¹ B ⁺ ) is separated using the difference in mass. Further, the mass spectrometer has an Al analysis tube bent in a curved shape.

  Next, the extracted impurity ions are accelerated by an acceleration tube. The impurity ions accelerated to a predetermined acceleration voltage are formed into a desired beam shape by the lens. Then, an ion beam with good uniformity in the wafer surface is formed by the scanner unit, and this ion beam flows into the wafer processing chamber and is driven into a wafer which is an object to be processed mounted on a mounting table in the wafer processing chamber.

JP 2002-8580 A (second to third paragraphs)

By the way, when ion implantation is performed on a single crystal such as a silicon wafer, a desired impurity concentration may not be obtained at an appropriate depth if the crystal orientation of the wafer surface is different from the intended orientation. This is widely known to be caused by channeling, and is an inevitable problem when ions are implanted into a single crystal silicon wafer.
However, even if constant channeling occurs during ion implantation, the influence of channeling can be reduced if the phenomenon of channeling can be controlled.

As a method for controlling the above-mentioned channeling, for example, there are the following methods.
When the wafer is manufactured with a predetermined plane orientation, for example, by implanting ions from a direction inclined by 90 ° to 7 ° with respect to the wafer surface, the channeling effect can be kept constant and the influence of channeling can be suppressed. Is possible.

  However, the crystal orientation of the wafer is not manufactured with complete accuracy, and normally, the crystal orientation of the wafer is manufactured so as to be distributed in a range of about ± 1 °. Channeling effects may vary from wafer to wafer due to such variations in crystal orientation of the wafer. In addition, the effect of channeling may vary depending on the wafer placement error caused by the wafer holder in the ion implantation apparatus.

As a method to prevent the desired impurity concentration from being obtained at an appropriate depth due to variations in the effects of channeling as described above, the ion beam direction is controlled by measuring the surface orientation of the wafer using Rutherford backscattering etc. It has been proposed to do so (see Japanese translations of PCT publication No. 2003-511845).
However, in order to use the Rutherford backscattering described above, it is necessary to implant some element into the wafer, so the plane orientation cannot be measured for each product wafer. Therefore, it is impossible to control the direction of the ion beam for each product wafer.

  The present invention has been made in consideration of the above-described circumstances, and its purpose is to measure the surface orientation for each substrate to be processed, and to perform ion implantation while controlling the influence of channeling for each substrate to be processed. An object of the present invention is to provide an ion implantation apparatus and a semiconductor device manufacturing method.

In order to solve the above problems, an ion implantation apparatus according to the present invention is an ion implantation apparatus for implanting impurity ions into a substrate to be processed.
A mechanism for measuring the surface orientation of the substrate to be processed by X-rays;
A mechanism for performing alignment based on the plane orientation of the substrate to be processed measured by the mechanism;
It comprises.

  According to the ion implantation apparatus, the surface orientation of the substrate to be processed can be measured by X-rays, and the substrate to be processed can be aligned based on the measurement result. For this reason, it is possible to implant the impurity ions while suppressing the deviation of the surface orientation of the substrate to be processed and making the channeling effect substantially constant. In other words, by measuring the surface orientation for each substrate to be processed, it is possible to perform ion implantation while controlling the influence of channeling for each substrate to be processed.

An ion implantation apparatus according to the present invention is an ion implantation apparatus for implanting impurity ions into a substrate to be processed.
A holding table for holding the substrate to be processed;
A goniometer that moves the holding table;
An X-ray irradiation mechanism for irradiating the substrate to be processed held on the holding table with X-rays;
An X-ray detector that detects reflected X-rays reflected by the substrate to be processed by the X-rays irradiated by the X-ray irradiation mechanism;
It comprises.

  According to the ion implantation apparatus, after the substrate to be processed is held on the holding table, the substrate to be processed is irradiated with X-rays by the X-ray irradiation mechanism, and the X-ray reflected by the substrate to be processed is detected by the X-ray detection unit. Thus, the surface orientation of the substrate to be processed is measured, and this is performed while moving the holding table with a goniometer to align the substrate to be processed, and then ion implantation is performed on the substrate to be processed. For this reason, variation in channeling effect between substrates to be processed can be suppressed, and it is possible to implant impurity ions with the channeling effect substantially constant. In other words, by measuring the surface orientation for each substrate to be processed, it is possible to perform ion implantation while controlling the influence of channeling for each substrate to be processed.

In the ion implantation apparatus according to the present invention, the X-ray irradiation mechanism includes an X-ray tube that emits X-rays, and a slit that passes X-rays emitted from the X-ray tube. Also good.
In the ion implantation apparatus according to the present invention, an ion source for ionizing an impurity gas, a mass analyzer for extracting impurity ions to be implanted into the substrate to be processed among impurities ionized by the ion source, and the mass analysis It is preferable to further include an accelerating tube for accelerating the impurity ions extracted by the vessel and a lens for shaping the impurity ions accelerated by the accelerating tube into a desired beam shape.

  In the method for manufacturing a semiconductor device according to the present invention, the surface orientation of the substrate to be processed is measured by X-rays, and after aligning the substrate to be processed based on the measurement result, impurity ions are implanted into the substrate to be processed. Process. By measuring the plane orientation for each substrate to be processed in this way, it becomes possible to perform ion implantation while controlling the influence of channeling for each substrate to be processed.

  In the method of manufacturing a semiconductor device according to the present invention, a substrate to be processed is held on a holding table with a goniometer, the substrate to be processed is irradiated with X-rays, the X-rays are reflected by the substrate to be processed, and the reflected X A line is detected by an X-ray detection unit to measure the surface orientation of the substrate to be processed, and the substrate is aligned by moving the holding table with the goniometer based on the measurement result. A step of implanting impurity ions into the processing substrate.

  According to the method for manufacturing a semiconductor device, after the substrate to be processed is held on the holding table, the surface orientation of the substrate to be processed is measured by X-rays, and the substrate to be processed is aligned based on the measurement result to perform ion implantation. Is going. For this reason, it is possible to implant impurity ions with the channeling effect substantially constant. In other words, by measuring the surface orientation for each substrate to be processed, it is possible to perform ion implantation while controlling the influence of channeling for each substrate to be processed.

  In the method for manufacturing a semiconductor device according to the present invention, when measuring the surface orientation of the substrate to be processed, the surface orientation is measured at a plurality of locations on the substrate to be processed, and the results of the measurement at the plurality of locations are used. It is also possible to align the substrate to be processed. Thereby, it becomes possible to measure the surface orientation with higher accuracy, and the alignment accuracy can be further improved.

  In the method for manufacturing a semiconductor device according to the present invention, the step of implanting impurity ions into the substrate to be processed may be a step of implanting channel dope ions into a silicon substrate. Since channel-doped ion implantation is an important ion implantation process for determining device characteristics, by performing ion implantation while controlling the influence of channeling in this process, variations in device characteristics can be effectively reduced. .

A method of manufacturing a semiconductor device according to the present invention includes a step of forming a gate insulating film on a surface of a semiconductor substrate,
By holding the semiconductor substrate on a holding table with a goniometer, irradiating the semiconductor substrate with X-rays, reflecting the X-rays with the semiconductor substrate, and detecting the reflected X-rays with an X-ray detector, Measuring the surface orientation of the semiconductor substrate, and aligning the semiconductor substrate by moving the holding table with the goniometer based on the measurement results;
Implanting channel-doped impurity ions into the semiconductor substrate through the silicon film and the gate insulating film;
It comprises.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below with reference to the drawings.
(Embodiment 1)
FIG. 1 is a configuration diagram showing an ion implantation apparatus according to Embodiment 1 of the present invention. This ion implantation apparatus has a mechanism for measuring the crystal orientation of a silicon wafer, which is a substrate to be processed, by X-rays, measures the crystal orientation for each silicon wafer, performs alignment of the silicon wafer based on the measurement result, and performs ionization. To be injected.

  The ion implantation apparatus shown in FIG. 1 includes an ion implantation mechanism that implants ions into a silicon wafer 2 that is a substrate to be processed, and a surface orientation measurement mechanism that measures the surface orientation of the silicon wafer 2 using X-rays. The ion implantation mechanism includes an ion source 7, an extraction electrode (not shown), a mass analyzer 8, a beam line unit 13, a processing chamber 12, and a wafer holder (platen) 1 with a goniometer.

  The ion source 7 ionizes the impurity gas. The extraction electrode extracts ionized impurities and draws them into the mass analyzer 8. The mass analyzer 8 extracts impurity ions implanted into the silicon wafer, and has an Al analysis tube (not shown) bent in a curved shape. The beam line unit 13 includes an acceleration tube 9, a lens 10, and a scan electrode 11.

The acceleration tube 9 accelerates impurity ions extracted by the mass analyzer 8. The lens 10 and the scan electrode 11 are for forming impurity ions into a desired beam shape to form an ion beam with good uniformity within the wafer surface.
A processing chamber 12 is connected to the beam line unit 13, and a platen 1 with a goniometer is disposed in the processing chamber 12. The platen 1 holds a silicon wafer and can be moved with high accuracy by a goniometer.

  The plane orientation measuring mechanism includes an X-ray source (X-ray irradiation mechanism) 3 and a scintillation counter 6 that is an X-ray detector. The X-ray source 3 emits X-rays and has an X-ray tube 3a and a slit 3b. The scintillation counter 6 detects reflected X-rays reflected from the surface of the silicon wafer by the X-rays irradiated from the X-ray source.

Next, a method for ion implantation using the ion implantation apparatus will be described.
First, a silicon wafer is held on the platen 1 with a goniometer. The silicon wafer 2 has a predetermined plane orientation, and the plane orientation is manufactured so as to be distributed in a range of about ± 1 °. That is, there is a variation in plane orientation of about ± 1 ° between silicon wafers.

Thereafter, the plane orientation of the silicon wafer 2 is measured by the following method.
The surface of the silicon wafer 2 is irradiated with X-rays from the X-ray source 3. At this time, the incident X-ray 4 from the X-ray tube 3 a passes through the slit 3 b and is reflected on the surface of the silicon wafer 2, and enters the scintillation counter 6, which is an X-ray detector, as reflected X-ray 5. Here, since the reflection angle θ is known in advance according to Bragg's law, the scintillation counter 6 is disposed at a position corresponding to the reflection angle. That is, when the silicon wafer 2 has a predetermined plane orientation (surface orientation with no error), the reflected X-ray 5 enters the scintillation counter 6 as planned, and the silicon wafer 2 is ion-implanted at the same position. Thus, the scintillation counter 6 is arranged at a position where the channeling effect can be controlled to be constant. Therefore, when the silicon wafer 2 has a desired plane orientation, this is confirmed by the reflected X-rays 5 and the silicon wafer 2 proceeds to the ion implantation process as it is.

  However, if there is a variation in the surface orientation of the silicon wafer 2, the platen 1 on which the silicon wafer 2 is placed is moved by a goniometer within a variation of ± 1 °, and the reflected X-ray 5 is synthesized at that time. Detect with counter 6. Then, when the reflected X-ray 5 as detected by the scintillation counter 6 is detected, the movement of the platen 1 is stopped. Thus, the silicon wafer 2 is aligned again at a position where the channeling effect can be controlled to be constant.

Next, the impurity gas is ionized in the ion source 7 and the ionized impurity is extracted by the extraction electrode. The extracted impurity ions are drawn into the mass analyzer 8 using an analysis electromagnet or the like, and the impurity ions to be implanted into the silicon wafer 2 are extracted in the mass analyzer 8. The mass analyzer 8 normally generates a plurality of types of ions such as ⁴⁹ BF ₂ ⁺ , ¹¹ B ⁺ , and ¹⁰ B ^{+ in} the ion source. ¹¹ B ⁺ ) is separated using the difference in mass.

  Next, the extracted impurity ions are accelerated by the acceleration tube 9. The impurity ions accelerated to a predetermined acceleration voltage are formed into a desired beam shape by the lens 10. Then, an ion beam having a good uniformity in the wafer surface is formed by the scan electrode 11, and this ion beam flows into the processing chamber 12, and is applied to the silicon wafer 2 that is an object to be processed placed on the platen 1 in the processing chamber. It is driven in.

  In the first embodiment, the surface orientation of the silicon wafer 2 is measured at one point on the silicon wafer by X-rays. However, the surface orientation can be measured at a plurality of points on the silicon wafer. It is. In this case, an average value of the plurality of measurement results is taken, and the silicon wafer is aligned again based on the average value. Thereby, the in-plane dispersion | variation by the effect of channeling can be suppressed.

  According to the first embodiment, after the silicon wafer 2 is held on the platen 1, the surface orientation of the silicon wafer 2 is measured by X-rays, and the silicon wafer 2 is aligned again based on the measurement result, and ion implantation is performed. Is going. Therefore, variation in channeling effect between wafers can be suppressed, and impurity ions can be implanted with the channeling effect substantially constant. That is, by measuring the plane orientation for each silicon wafer, it becomes possible to perform ion implantation while controlling the influence of channeling for each silicon wafer. Therefore, variations in device characteristics between wafers due to ion implantation can be reduced.

  Further, in this embodiment, since the plane orientation of the silicon wafer 2 is measured and aligned again, variation in channeling effect due to the installation error of the silicon wafer 2 by the platen 1 can be suppressed.

(Embodiment 2)
2A to 2D are cross-sectional views illustrating a method for manufacturing a semiconductor device according to a second embodiment of the present invention. This method of manufacturing a semiconductor device includes a step of ion implantation using the ion implantation apparatus according to the first embodiment.

  First, as shown in FIG. 2A, a LOCOS element isolation film 15 is formed on a silicon substrate (silicon wafer) 2, and a thickness of 15 nm is formed on the silicon substrate between the LOCOS element isolation films 15 by thermal oxidation. A gate oxide film 16 is formed to the extent.

Next, the silicon substrate 2 is placed and held on the platen 1 with a goniometer of the ion implantation apparatus shown in FIG.
Next, the plane orientation of the silicon substrate 2 is measured by the following method, and the silicon substrate 2 is aligned by moving the platen 1 with a goniometer based on the measurement result.

  The surface of the silicon substrate 2 is irradiated with X-rays from the X-ray source 3. At this time, the incident X-ray 4 from the X-ray tube 3 a passes through the slit 3 b and is reflected on the surface of the silicon substrate 2, and enters the scintillation counter 6 which is an X-ray detector as the reflected X-ray 5. Here, since the reflection angle θ is known in advance according to Bragg's law, the scintillation counter 6 is disposed at a position corresponding to the reflection angle.

  Here, when the surface orientation of the silicon substrate 2 varies, the platen 1 on which the silicon substrate 2 is placed is moved by a goniometer, and the reflected X-ray 5 is detected by the scintillation counter 6 at that time. Then, when the reflected X-ray 5 as detected by the scintillation counter 6 is detected, the movement of the platen 1 is stopped. Thus, the silicon wafer 2 is aligned again at a position where the channeling effect can be controlled to be constant.

After that, as shown in FIG. 2B, channel dope ion implantation is performed on the silicon substrate 2 by the following method.
In the ion source 7 shown in FIG. 1, the impurity gas is ionized, and the ionized impurity is extracted by the extraction electrode. The extracted impurity ions are drawn into the mass analyzer 8 using an analysis electromagnet or the like, and the impurity ions implanted into the silicon substrate 2 are extracted in the mass analyzer 8.

Next, the extracted impurity ions are accelerated by the acceleration tube 9. The impurity ions accelerated to a predetermined acceleration voltage are formed into a desired beam shape by the lens 10. Then, an ion beam having a good uniformity in the wafer surface is formed by the scan electrode 11, and this ion beam flows into the processing chamber 12 and is driven into the silicon substrate 2 placed on the platen 1 in the processing chamber. As the ion implantation conditions at this time, for example, an acceleration energy of 120 KeV and a dose of 3.5 × 10 ¹² cm ⁻² are used. In this way, the channel dope layer 18 is formed on the silicon substrate 2.

Thereafter, as shown in FIG. 2C, a polysilicon film 18 is deposited on the gate oxide film 16 and the LOCOS element isolation film 15 by a chemical vapor deposition (CVD) method.
Next, as shown in FIG. 2D, the polysilicon film 18 is patterned to form a gate electrode on the silicon substrate 2 via the gate oxide film 16. The polysilicon film 18 is patterned by, for example, applying a photoresist film (not shown) on the polysilicon film 18, exposing and developing the photoresist film to form a resist pattern, and using the resist pattern as a mask. This is performed by etching the polysilicon film 18.

  Next, impurity ions 20 are formed in the silicon substrate 2 by implanting impurity ions into the silicon substrate 2 using the gate electrode as a mask. Next, an interlayer insulating film 21 made of a silicon oxide film or the like is formed on the entire surface including the gate electrode by a CVD method. Next, a contact hole is formed in the interlayer insulating film 21, and an Al alloy film is formed in the contact hole and on the interlayer insulating film 21 by sputtering. Next, by patterning this Al alloy film, an Al alloy wiring 22 is formed in the contact hole and on the interlayer insulating film 21, and the Al alloy wiring 22 is electrically connected to the impurity layer 20.

In the second embodiment, the same effect as in the first embodiment can be obtained.
That is, after holding the silicon substrate 2 on the platen 1, the plane orientation of the silicon substrate 2 is measured by X-rays, and the silicon substrate 2 is realigned based on the measurement result to perform channel dope ion implantation. For this reason, it is possible to implant impurity ions with the channeling effect substantially constant. That is, by measuring the plane orientation for each silicon substrate, it becomes possible to perform channel dope ion implantation while controlling the influence of channeling for each silicon substrate. Therefore, variations in transistor characteristics between silicon substrates due to channel-doped ion implantation can be reduced. Further, since the plane orientation of the silicon substrate 2 is measured and the alignment is performed again, variation in channeling effect due to the installation error of the silicon substrate 2 by the platen 1 can be suppressed.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the second embodiment, a typical example in which the present invention is applied when channel-doped ion implantation is performed on a silicon substrate is described. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention is also applicable when ion implantation is performed in various regions other than the dope.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows the ion implantation apparatus by Embodiment 1 of this invention. 9A to 9D are cross-sectional views illustrating a method for manufacturing a semiconductor device according to a second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Wafer holder with goniometer, 2 ... Silicon wafer (silicon substrate), 3 ... X-ray source (X-ray irradiation mechanism), 3a ... X-ray tube, 3b ... Slit, 4 ... Incident X-ray, 5 ... Reflected X-ray , 6 ... scintillation counter, 7 ... ion source, 8 ... mass analyzer, 9 ... accelerator tube, 10 ... lens, 11 ... scan electrode, 12 ... processing chamber, 13 ... beam line section, 15 ... LOCOS element separation film , 16 ... Gate oxide film, 17 ... Channel doped layer, 18 ... Polysilicon film, 19 ... Impurity layer in source and drain regions, 20 ... Interlayer insulating film, 21 ... Al alloy wiring

Claims (9)

In an ion implantation apparatus for implanting impurity ions into a substrate to be processed,
A mechanism for measuring the surface orientation of the substrate to be processed by X-rays;
A mechanism for performing alignment based on the plane orientation of the substrate to be processed measured by the mechanism;
An ion implantation apparatus comprising: In an ion implantation apparatus for implanting impurity ions into a substrate to be processed,
A holding table for holding the substrate to be processed;
A goniometer that moves the holding table;
An X-ray irradiation mechanism for irradiating the substrate to be processed held on the holding table with X-rays;
An X-ray detector that detects reflected X-rays reflected by the substrate to be processed by the X-rays irradiated by the X-ray irradiation mechanism;
An ion implantation apparatus comprising: The ion implantation apparatus according to claim 2, wherein the X-ray irradiation mechanism includes an X-ray tube that emits X-rays and a slit through which the X-rays emitted from the X-ray tube pass. An ion source for ionizing an impurity gas, a mass analyzer for extracting impurity ions to be implanted into the substrate to be processed among impurities ionized by the ion source, and an acceleration tube for accelerating the impurity ions extracted by the mass analyzer 4. The ion implantation apparatus according to claim 1, further comprising a lens that shapes the impurity ions accelerated by the acceleration tube into a desired beam shape. 5. A method for manufacturing a semiconductor device, comprising: measuring a plane orientation of a substrate to be processed by X-rays, aligning the substrate to be processed based on a result of the measurement, and then implanting impurity ions into the substrate to be processed. By holding the substrate to be processed on a holding table with a goniometer, irradiating the substrate to be processed with X-rays, reflecting the X-rays with the substrate to be processed, and detecting the reflected X-rays with an X-ray detector Measuring the surface orientation of the substrate to be processed, and injecting impurity ions into the substrate to be processed after aligning the substrate to be processed by moving the holding table with the goniometer based on the measurement result. A method for manufacturing a semiconductor device. 7. When measuring the surface orientation of the substrate to be processed, the surface orientation is measured at a plurality of locations on the substrate to be processed, and the substrate to be processed is aligned based on the measurement results at the plurality of locations. The manufacturing method of the semiconductor device of description. The method for manufacturing a semiconductor device according to claim 5, wherein the step of implanting impurity ions into the substrate to be processed is a step of implanting channel dope ions into a silicon substrate. Forming a gate insulating film on the surface of the semiconductor substrate;
By holding the semiconductor substrate on a holding table with a goniometer, irradiating the semiconductor substrate with X-rays, reflecting the X-rays with the semiconductor substrate, and detecting the reflected X-rays with an X-ray detector, Measuring the surface orientation of the semiconductor substrate, and aligning the semiconductor substrate by moving the holding table with the goniometer based on the measurement results;
Implanting channel-doped impurity ions into the semiconductor substrate through the silicon film and the gate insulating film;
A method for manufacturing a semiconductor device comprising:

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