JP7392578B2 - High frequency semiconductor device manufacturing method and high frequency semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a high frequency semiconductor device and a high frequency semiconductor device.

High frequency devices used in high frequency applications are broadly classified into active devices and passive devices. Examples of active devices include diodes and transistors (eg, FETs and HEMTs). Passive elements include elements such as resistors, capacitors, and filters, and wiring (transmission lines) that connect the elements.

As schematically shown in FIG. 6, in the previous high-frequency element 20', the active element 20a and the element 20b-1 of the passive element 20b were connected by wiring (transmission line) 20b-2 for each component. . Such a high frequency element 20' uses an active element 20a and a passive element 20b, which are each manufactured separately.

On the other hand, in recent years, semiconductor devices (for example, monolithic microwave integrated circuits (MMIC)) in which active elements and passive elements (including wiring) are fabricated all at once on a semiconductor substrate have been used as high-frequency elements.

Now, with the arrival of 5G, devices need to support a wide range of frequency bands, and many high-frequency components such as filters are becoming necessary. In particular, semiconductor devices used in a high frequency region, ie, semiconductor devices for radio frequency (RF) applications, are required to have higher performance.

High-frequency filters using silicon substrates with an SOI structure have been attracting attention because of their compatibility with CMOS processes and their ability to be mass-produced. From the viewpoint of preventing crosstalk, emphasis has been placed on harmonic characteristics, and various measures have been taken to improve this, such as increasing the resistivity of the substrate and introducing a charge storage layer.

A concrete solution is to first increase the resistivity of the support substrate. As for specific resistivity values, for example, Patent Document 1 describes an electrical resistivity that is typically higher than 500 Ω·cm, preferably higher than 1000 Ω·cm, and still more preferably higher than 3000 Ω·cm. It is said that one must have one.

Furthermore, Patent Document 2 describes a support substrate having an SOI structure, and a new intermediate semiconductor layer (charge trapping layer or trap rich layer) such as Poly-Si between the support substrate and a buried oxide layer (BOX film). A method for manufacturing a high-frequency SOI substrate (TR-SOI substrate) equipped with a TR layer) is described.

The high-frequency characteristics of such a high-frequency substrate were measured by removing the SOI layer of the TR-SOI substrate and forming a Co-Planar Waveguide (CPW) 5 as shown in FIGS. 7 and 8 on the BOX layer using Al electrodes. There is a second harmonic (2HD) characteristic.

The CPW 5 has a structure in which metal electrodes 50a are arranged in parallel with a gap, and a linear central metal electrode 50b is formed in parallel with the metal electrodes 50a in the center of the gap, as shown in the example shown in FIGS. 7 and 8. , and transmits electromagnetic waves by an electric field 50c directed from the central metal electrode 50b toward the left and right metal electrodes 50a in FIG. Refers to element 5 of the structure.

Note that the high-frequency SOI substrate is usually used as an SOI structure, but in order to easily evaluate 2HD characteristics, the active layer of SOI (SOI layer) is removed to expose the BOX layer, and a layer is placed on top of this. A CPW is formed and the 2HD characteristics are evaluated. When an element is actually manufactured as a device, a portion that operates as an active element (such as a transistor) is formed on the SOI layer, but a passive element (such as a filter) is manufactured on a portion from which the SOI layer is removed. In other words, by using an SOI substrate, it becomes possible to form active elements and passive elements on one semiconductor substrate.

Furthermore, harmonics are high-order frequency components that are integral multiples of the original frequency.The original frequency is defined as the fundamental wave, and those with twice the frequency (half the wavelength) are defined as 2HD. ing. In high-frequency circuits, a substrate with low harmonics is required to avoid interference caused by harmonics, and for this purpose, as mentioned above, in TR-SOI, a TR layer is formed on the support substrate, and the support substrate has a high resistivity. The 2HD characteristics have been improved.

Further, Patent Document 3 discloses that traps are distributed within an oxide layer by electron beam irradiation to generate oxide film trap charges, thereby improving the RF device performance of the SOI substrate.

Special table 2015-503853 publication JP 2019-129195 Publication JP 2019-41115 Publication

Even with the trap-rich layer described above, the RF characteristics depend on the resistivity of the supporting substrate. However, it is very difficult to increase the resistivity of the support substrate, and as mentioned above, if you try to obtain an electrical resistivity higher than 3000 Ωcm, for example, in the case of P-type boron, it is difficult to increase the resistivity of 3×10 ¹² atoms/cm ³ . It is necessary to have an extremely low dopant concentration, and it has been difficult to further increase the resistivity due to the influence of impurities in the raw materials.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a high-frequency semiconductor device that can manufacture a high-frequency semiconductor device with excellent high-frequency characteristics, and a high-frequency semiconductor device with excellent high-frequency characteristics. shall be.

In order to solve the above problems, in the present invention,
A method for manufacturing a high-frequency semiconductor device used in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate, the method comprising:
preparing the semiconductor substrate containing a dopant;
A method for manufacturing a high frequency semiconductor device is provided, the method comprising the step of inactivating the dopant in the semiconductor substrate by irradiating at least a high frequency element forming portion of the semiconductor substrate with a particle beam.

In the method for manufacturing a high-frequency semiconductor device of the present invention, by irradiating at least the high-frequency element forming portion of the semiconductor substrate with a particle beam, point defects can be introduced into the semiconductor substrate and carriers can be trapped, thereby making it possible to trap carriers in the semiconductor substrate. Inactivates the dopants inside. As a result, in the method for manufacturing a high-frequency semiconductor device of the present invention, at least the high-frequency element forming portion of the semiconductor substrate can be made to have a high resistivity, and the high-frequency characteristics, particularly the harmonic characteristics, of the high-frequency semiconductor device to be manufactured can be improved. . That is, with the method for manufacturing a high frequency semiconductor device of the present invention, a high frequency semiconductor device with excellent high frequency characteristics can be manufactured.

The semiconductor substrate preferably includes a silicon single crystal substrate having a resistivity of 500 Ω·cm or more.
By using such a semiconductor substrate, a semiconductor device having better high frequency characteristics can be manufactured.

Before forming the high frequency element on the semiconductor substrate, at least the high frequency element forming portion of the semiconductor substrate where the high frequency element is formed can be irradiated with the particle beam.
Alternatively, after forming the high frequency element on the semiconductor substrate, the particle beam may be irradiated to at least the high frequency element forming portion of the semiconductor substrate in which the high frequency element is formed.

In the method for manufacturing a high-frequency semiconductor device of the present invention, whether the particle beam irradiation to the high-frequency element formation portion is performed before or after the high-frequency element is formed, the high-frequency characteristics can be similarly improved. Excellent high frequency semiconductor devices can be manufactured.

It is preferable to irradiate an electron beam as the particle beam.
Compared to other particle beams, electron beams are commonly used for lifetime control of power devices, and have many advantages such as high transparency and uniform irradiation in the depth direction of semiconductor substrates.

The semiconductor substrate is an SOI substrate,
silicon single crystal substrate,
embedded insulating layer,
It is preferable to use an SOI substrate comprising: a charge trapping layer as an intermediate layer formed between the silicon single crystal substrate and the buried insulating layer; and an SOI layer disposed on the buried insulating layer.

By using such an SOI substrate as a semiconductor substrate, a high-performance high-frequency semiconductor device can be manufactured due to the high resistivity of the silicon single crystal substrate that is the supporting substrate and the charge trapping effect of the charge trapping layer.

The present invention also provides a high-frequency semiconductor device for use in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate,
The semiconductor substrate contains a dopant,
The present invention provides a high frequency semiconductor device, wherein the dopant in the semiconductor substrate is inactivated in at least a high frequency element formation portion in which the high frequency element is formed in the semiconductor substrate.

In the high-frequency semiconductor device of the present invention, the dopant in the semiconductor substrate of at least the high-frequency element forming portion of the semiconductor device is inactivated, so that the semiconductor substrate can exhibit high resistivity. It can exhibit excellent high frequency characteristics, especially excellent harmonic characteristics.

The semiconductor substrate is an SOI substrate,
silicon single crystal substrate,
embedded insulating layer,
The SOI substrate preferably includes: a charge trapping layer as an intermediate layer formed between the silicon single crystal substrate and the buried insulating layer; and an SOI layer disposed on the buried insulating layer.

By providing such an SOI substrate as a semiconductor substrate, a high frequency semiconductor device can be obtained that exhibits better performance due to the high resistivity of the silicon single crystal substrate that is the supporting substrate and the charge trapping effect of the charge trapping layer. be able to.

As described above, according to the method for manufacturing a high-frequency semiconductor device of the present invention, at least the high-frequency element forming portion of the semiconductor substrate can be made to have a high resistivity, and the high-frequency characteristics, particularly the harmonic characteristics, of the high-frequency semiconductor device to be manufactured can be improved. can do. As a result, with the method for manufacturing a high frequency semiconductor device of the present invention, a high frequency semiconductor device with excellent high frequency characteristics can be manufactured.

Further, in the high-frequency semiconductor device of the present invention, the dopant in the semiconductor substrate is inactivated at least in the high-frequency element forming portion of the semiconductor device, so that the semiconductor substrate can exhibit high resistivity. This allows it to exhibit excellent high frequency characteristics.

1 is a schematic cross-sectional view showing an example of a high frequency semiconductor device that can be manufactured by the method for manufacturing a high frequency semiconductor device of the present invention. 2 is a flow diagram of Example 1. FIG. 3 is a flow diagram of Example 2. FIG. It is a flowchart of a comparative example. 3 is a graph showing the results of second harmonic characteristic evaluation of semiconductor substrates obtained in Example 1 and Comparative Example, respectively. FIG. 1 is a schematic cross-sectional view showing an example of a conventional high-frequency element. FIG. 2 is a schematic plan view of an example of a Co-Planar Waveguide (CPW) used to evaluate second-order harmonic characteristics. 8 is a cross-sectional view taken along line XX of CPW in FIG. 7. FIG.

As described above, there has been a need for a method of manufacturing a high frequency semiconductor device that can manufacture a high frequency semiconductor device with excellent high frequency characteristics, and to develop a high frequency semiconductor device with excellent high frequency characteristics.

As a result of intensive studies on the above-mentioned problems, the present inventors have found that, in addition to dopant control, carriers can be improved by irradiating particle beams onto at least the high-frequency element formation area of the semiconductor substrate and introducing point defects there. The present invention was completed by discovering that it is possible to increase the resistivity of a semiconductor substrate and improve high frequency characteristics by trapping dopants in point defects and inactivating them.

That is, the present invention is a method for manufacturing a high-frequency semiconductor device used in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate, comprising:
preparing the semiconductor substrate containing a dopant;
A method for manufacturing a high-frequency semiconductor device, comprising the step of inactivating the dopant in the semiconductor substrate by irradiating at least a high-frequency element forming portion of the semiconductor substrate with a particle beam.

The present invention also provides a high-frequency semiconductor device for use in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate,
The semiconductor substrate contains a dopant,
The high-frequency semiconductor device is characterized in that the dopant in the semiconductor substrate is inactivated in at least a high-frequency element formation portion in which the high-frequency element is formed in the semiconductor substrate.

Hereinafter, the present invention will be explained in detail with reference to the drawings, but the present invention is not limited thereto.

[Manufacturing method of high frequency semiconductor device]
The present invention is a method for manufacturing a high-frequency semiconductor device used in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate, comprising:
preparing the semiconductor substrate containing a dopant;
A method for manufacturing a high-frequency semiconductor device, comprising the step of inactivating the dopant in the semiconductor substrate by irradiating at least a high-frequency element forming portion of the semiconductor substrate with a particle beam.

According to the method for manufacturing a high frequency semiconductor device of the present invention, for example, a high frequency semiconductor device schematically shown in FIG. 1 can be manufactured.

A high frequency semiconductor device 100 shown in FIG. 1 includes a semiconductor substrate 10 and a high frequency element 20 formed on the semiconductor substrate 10.

High frequency element 20 includes an active element 20a and a passive element 20b. Examples of the active element 20a include elements such as diodes and transistors (eg, FETs and HEMTs). The passive element 20b includes an element 20b-1 such as a resistor, a capacitor, and a filter, and a wiring (transmission line) 20b-2 that electrically couples the element 20b-1 and the active element 20a.

Semiconductor substrate 10 includes a dopant. Further, the semiconductor substrate 10 has a high frequency element forming portion 12 in which a high frequency element 20 is formed. The high frequency element formation section 12 includes an active element formation section 12a in which an active element 20a is formed, and a passive element formation section 12b in which a passive element 20b is formed.

Although FIG. 1 shows a portion of the semiconductor substrate 10 in which the high-frequency element 20 is formed as a high-frequency element formation section 12, in the present invention, a high-frequency element including an active element formation section 12a and a passive element formation section 12b is used. The formation portion may be a portion of the semiconductor substrate on which the high frequency element is to be formed before forming the high frequency element.

In the present invention, the dopant in the semiconductor substrate 10 is inactivated at least in the high frequency element forming portion 12 of the semiconductor substrate 10.

Further, the high frequency semiconductor device that can be manufactured by the high frequency semiconductor device manufacturing method of the present invention is not limited to the high frequency semiconductor device 100 shown in FIG. For example, the high frequency element 20 may be composed of an active element 20a without including a passive element.

Next, a method for manufacturing a high frequency semiconductor device according to the present invention will be explained in detail.

The method for manufacturing a high-frequency semiconductor device of the present invention is characterized by including a step of irradiating at least a high-frequency element forming portion of a semiconductor substrate containing a dopant with a particle beam to inactivate the dopant in the semiconductor substrate.

In this inactivation, point defects are formed in the semiconductor substrate by irradiation with a particle beam, and these act as carrier traps, trapping carriers in the semiconductor substrate and inactivating the dopant. It is thought that this increases the resistivity of the substrate. By reducing the number of carriers (increasing the resistivity) in this way, it is thought that when a high frequency is applied, there are no carriers that follow the high frequency, thereby reducing harmonics. The particle beam irradiated at this time can be an electron beam or a proton beam.

In the method for manufacturing a high-frequency semiconductor device of the present invention, at least a high-frequency element forming portion of the semiconductor substrate is irradiated with a particle beam. That is, the present invention is not limited to irradiating the particle beam only to the high-frequency element forming portion. Although the entire surface of the semiconductor substrate may be irradiated with the particle beam, the effect is particularly noticeable on a portion where a high frequency element such as a filter is formed, or a high frequency element formation portion where a high frequency element is formed. In this way, by irradiating at least the high-frequency element forming portion of the semiconductor substrate with a particle beam, the dopants in the semiconductor substrate can be inactivated and the high-frequency characteristics can be improved.

Before forming a high frequency element on a semiconductor substrate, a particle beam may be irradiated to at least a high frequency element forming portion of the semiconductor substrate in which a high frequency element is formed. Alternatively, after forming the high frequency element on the semiconductor substrate, the particle beam may be irradiated to at least the high frequency element forming portion of the semiconductor substrate in which the high frequency element is formed.

In the method for manufacturing a high-frequency semiconductor device of the present invention, whether the particle beam irradiation to the high-frequency element formation portion is performed before or after the high-frequency element is formed, the high-frequency characteristics can be similarly improved. Excellent high frequency semiconductor devices can be manufactured.

That is, a method for manufacturing a high-frequency semiconductor device according to one aspect of the present invention includes a step of preparing a semiconductor substrate containing a dopant, and a step of irradiating a particle beam to at least a high-frequency element forming portion of the semiconductor substrate that forms a high-frequency element. and a step of forming a high frequency element on the high frequency element forming part irradiated with the particle beam.

Further, a method for manufacturing a high-frequency semiconductor device according to another aspect of the present invention includes the steps of: preparing a semiconductor substrate containing a dopant; forming a high-frequency element on a high-frequency element forming portion of the semiconductor substrate; The method includes a step of inactivating dopants in the semiconductor substrate by irradiating a particle beam to at least a high-frequency element forming portion of the substrate in which a high-frequency element is formed.

It is preferable to irradiate an electron beam as the particle beam. Compared to other particle beams, electron beams are commonly used for lifetime control of power devices, and have many advantages such as high transparency and uniform irradiation in the depth direction of semiconductor substrates.
Furthermore, electron beams have strong transparency and can form defects uniformly over the depth of the substrate, making them very effective.

Further, the electron beam irradiation may be applied to the entire surface of the substrate on which the element is formed. In this case, the electron beam can be irradiated without considering the formation position of the element, which is simpler.

The semiconductor substrate is not particularly limited as long as it contains a dopant. The dopant is not particularly limited as long as it can be contained in the semiconductor substrate. Examples of the dopant include B, Ga, P, Sb, and As.

It is preferable to use a semiconductor substrate that includes a silicon single crystal substrate with a resistivity of 500 Ω·cm or more.
By using a silicon single crystal substrate exhibiting such resistivity, a high frequency semiconductor device having better high frequency characteristics can be manufactured.

An example of a semiconductor substrate including a silicon single crystal substrate is an SOI substrate.

The SOI substrate can include, for example, a silicon single crystal substrate as a supporting substrate, a buried insulating layer disposed on the silicon single crystal substrate, and an SOI layer disposed on the buried insulating layer.

It is preferable to use an SOI substrate that further includes a charge trapping layer as an intermediate layer formed between a silicon single crystal substrate serving as a supporting substrate and a buried insulating layer.

By using such an SOI substrate as a semiconductor substrate, a high-frequency semiconductor device can be obtained that exhibits better performance due to the high resistivity of the silicon single crystal substrate that is the supporting substrate and the charge trapping effect of the charge trapping layer. be able to.

By using the high-frequency semiconductor manufacturing method of the present invention, it is not only possible to fabricate a semiconductor device with better harmonic characteristics than before by using a high-resistivity support substrate, but also by using a substrate with relatively low resistivity. Even if there is a high resistivity, it is possible to achieve high resistivity. Furthermore, if there are variations in high-frequency characteristics within the plane of the support substrate (in the case of silicon substrates, a difference in resistivity occurs between the center and the outer periphery of the support substrate due to the shape of the solid-liquid interface during crystal growth). ), it is also possible to reduce in-plane variations by irradiation with a particle beam, such as an electron beam.

The high frequency element can include, for example, a passive element. With active devices, it is possible to "operate" the device in response to a signal to achieve a predetermined performance, but with passive devices such as filters, it is only possible to create predetermined characteristics at the beginning. Therefore, it is necessary to build in the desired performance as much as possible from the initial stage. Therefore, when the high frequency element includes a passive element and the high frequency element formation section includes the passive element formation section, the effect in the passive element formation section is more significant.

However, the effects of the present invention can be obtained even when the high frequency element includes both a passive element and an active element, or even when the high frequency element is composed of an active element.

Active devices include, for example, devices such as diodes and transistors (eg, FETs and HEMTs). Examples of passive elements include elements such as resistors, capacitors, and filters, and wiring (transmission lines) that electrically connects each element.

[High frequency semiconductor device]
The present invention also provides a high-frequency semiconductor device for use in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate,
The semiconductor substrate contains a dopant,
The high-frequency semiconductor device is characterized in that the dopant in the semiconductor substrate is inactivated in at least a high-frequency element formation portion in which the high-frequency element is formed in the semiconductor substrate.

In the high-frequency semiconductor device of the present invention, the dopant in the semiconductor substrate at least in the high-frequency element forming portion of the semiconductor device is inactivated, so that the semiconductor substrate can exhibit high resistivity, which makes it excellent. It can exhibit excellent high frequency characteristics, especially excellent harmonic characteristics.

The high frequency semiconductor device of the present invention can be manufactured, for example, by the method for manufacturing a high frequency semiconductor device of the present invention described above.

An example of the high frequency semiconductor device of the present invention is the high frequency semiconductor device 100 described above with reference to FIG.

As the semiconductor substrate and the high frequency element, those described above can be used.

In particular, the semiconductor substrate is an SOI substrate, which includes a silicon single crystal substrate, a buried insulating layer, a charge trapping layer as an intermediate layer formed between the silicon single crystal substrate and the buried insulating layer, and a charge trapping layer disposed on the buried insulating layer. It is preferable that the SOI substrate is provided with an SOI layer.

By providing such an SOI substrate as a semiconductor substrate, a high frequency semiconductor device can be obtained that exhibits better performance due to the high resistivity of the silicon single crystal substrate that is the supporting substrate and the charge trapping effect of the charge trapping layer. be able to.

Hereinafter, the present invention will be specifically explained using Examples and Comparative Examples, but the present invention is not limited thereto.

(Example 1)
In Example 1, a semiconductor substrate 10 was prepared according to the flowchart shown in FIG. 2, and an evaluation sample 100A was manufactured using this semiconductor substrate 10.

Support substrates 1 of boron-doped high resistivity silicon single crystal substrates (5000, 8000, 12500 Ω cm) with a diameter of 200 mm prepared by the FZ method were prepared, and a polysilicon layer was formed on these support substrates 1 at 1050°C. After that, the surface was polished to form a charge trapping layer (polysilicon layer) 3 having a thickness of 1.8 μm. In this way, a first composite body 10A including the support substrate 1 and the charge trapping layer 3 disposed on the support substrate 1 was prepared.

Next, a second composite 10B in which a 400 nm thermal oxide film (silicon oxide film) 4 as a buried insulating layer (BOX layer) is formed on the surface of another silicon single crystal substrate (a substrate to be an SOI layer) 2. prepared.

Next, a second composite 10B containing the embedded insulating layer 4 is added to the first composite 10A containing the supporting substrate 1 on which the charge trapping layer 3 is formed, and the charge capturing layer 3 and the embedded insulating layer 4 are They were attached so that they were in contact with each other. As a result, a support substrate (silicon single crystal substrate) 1, a buried insulating layer (silicon oxide film) 4, and a charge trapping layer as an intermediate layer (trap-rich layer) formed between the support substrate 1 and the buried insulating layer 4 are formed. A semiconductor substrate 10 was obtained, which is an SOI substrate including a (polysilicon layer) 3 and a substrate 2 serving as an SOI layer disposed on a buried insulating layer 4.

Thereafter, the substrate 2 serving as the SOI layer of the second composite 10B was removed, and a 400 nm embedded insulating layer 4 was transferred to the first composite 10A. As a result, a substrate 10C was manufactured in which a charge trapping layer 3 as an intermediate layer (trap rich layer) and a buried insulating layer 4 as an insulating film were formed on a high resistivity support substrate 1.

On this substrate 10C, an element was fabricated in which a CPW (line length: 2200 μm) 5 having the structure shown in FIGS. 7 and 8 was formed using aluminum electrodes. Thereafter, the entire surface of the substrate 10C was irradiated with an electron beam (acceleration energy: 2 MeV, dose: 1×10 ¹⁴ to 1×10 ¹⁶ /cm ² ) to produce an evaluation sample 100A of Example 1.

The second harmonic characteristics (2HD characteristics) (frequency: 1 GHz, input power: 15 dBm) of the produced evaluation sample 100A were measured.

(Example 2)
In Example 2, a semiconductor substrate 10 was prepared according to the flowchart shown in FIG. 3, and an evaluation sample 100B was manufactured using this semiconductor substrate 10.

Support substrates 1 of boron-doped high resistivity silicon single crystal substrates (5000, 8000, 12500 Ω cm) with a diameter of 200 mm prepared by the FZ method were prepared, and a polysilicon layer was formed on these support substrates 1 at 1050°C. After that, the surface was polished to form a charge trapping layer (polysilicon layer) 3 having a thickness of 1.8 μm. In this way, a first composite body 10A including the support substrate 1 and the charge trapping layer 3 disposed on the support substrate 1 was prepared.

Next, a second composite 10B in which a 400 nm thermal oxide film (silicon oxide film) 4 as a buried insulating layer (BOX layer) is formed on the surface of another silicon single crystal substrate (a substrate to be an SOI layer) 2. prepared.

Next, a second composite 10B containing the embedded insulating layer 4 is added to the first composite 10A containing the supporting substrate 1 on which the charge trapping layer 3 is formed, and the charge capturing layer 3 and the embedded insulating layer 4 are They were attached so that they were in contact with each other. As a result, a support substrate (silicon single crystal substrate) 1, a buried insulating layer (silicon oxide film) 4, and a charge trapping layer as an intermediate layer (trap-rich layer) formed between the support substrate 1 and the buried insulating layer 4 are formed. A semiconductor substrate 10 was obtained, which is an SOI substrate including a (polysilicon layer) 3 and a substrate 2 serving as an SOI layer disposed on a buried insulating layer 4.

Thereafter, the substrate 2 serving as the SOI layer of the second composite 10B was removed, and a 400 nm embedded insulating layer 4 was transferred to the first composite 10A. As a result, a substrate 10C was manufactured in which a charge trapping layer 3 as an intermediate layer (trap rich layer) and a buried insulating layer 4 as an insulating film were formed on a high resistivity support substrate 1.

The entire surface of the substrate 10C was irradiated with an electron beam (acceleration energy: 2 MeV, dose: 1×10 ¹⁴ to 1×10 ¹⁶ /cm ² ).

On this substrate 10C, an element was fabricated in which a CPW (line length: 2200 μm) 5 having the structure shown in FIGS. 7 and 8 was formed using aluminum electrodes. In this way, evaluation sample 100B of Example 2 was produced.

That is, in Example 2, an evaluation sample was prepared in the same manner as in Example 1 except that electron beam irradiation was performed before forming the CPW5.

The second harmonic characteristics (2HD characteristics) (frequency: 1 GHz, input power: 15 dBm) of the produced evaluation sample 100B were measured.

(Comparative example 1)
In Comparative Example 1, a semiconductor substrate 10 was prepared according to the flowchart shown in FIG. 4, and an evaluation sample 100C was manufactured using this semiconductor substrate 10.

Support substrates 1 of boron-doped high resistivity silicon single crystal substrates (5000, 8000, 12500 Ω cm) with a diameter of 200 mm prepared by the FZ method were prepared, and a polysilicon layer was formed on these support substrates 1 at 1050°C. After that, the surface was polished to form a charge trapping layer (polysilicon layer) 3 having a thickness of 1.8 μm. In this way, a first composite body 10A including the support substrate 1 and the charge trapping layer 3 disposed on the support substrate 1 was prepared.

Next, a second composite 10B in which a 400 nm thermal oxide film (silicon oxide film) 4 as a buried insulating layer (BOX layer) is formed on the surface of another silicon single crystal substrate (a substrate to be an SOI layer) 2. prepared.

Next, a second composite 10B containing the embedded insulating layer 4 is added to the first composite 10A containing the supporting substrate 1 on which the charge trapping layer 3 is formed, and the charge capturing layer 3 and the embedded insulating layer 4 are They were attached so that they were in contact with each other. As a result, a support substrate (silicon single crystal substrate) 1, a buried insulating layer (silicon oxide film) 4, and a charge trapping layer as an intermediate layer (trap-rich layer) formed between the support substrate 1 and the buried insulating layer 4 are formed. A semiconductor substrate 10 was obtained, which is an SOI substrate including a (polysilicon layer) 3 and a substrate 2 serving as an SOI layer disposed on a buried insulating layer 4.

Thereafter, the substrate 2 serving as the SOI layer of the second composite 10B was removed, and a 400 nm embedded insulating layer 4 was transferred to the first composite 10A. As a result, a substrate 10C was manufactured in which a charge trapping layer 3 as an intermediate layer (trap rich layer) and a buried insulating layer 4 as an insulating film were formed on a high resistivity support substrate 1.

On this substrate 10C, an element was fabricated in which a CPW (line length: 2200 μm) 5 having the structure shown in FIGS. 7 and 8 was formed using aluminum electrodes. In this way, evaluation sample 100C of Comparative Example 1 was produced.

That is, in Comparative Example 1, evaluation sample 100C was produced in the same manner as in Example 1 except that electron beam irradiation was not performed.

Thereafter, the second harmonic characteristics (2HD characteristics) (frequency: 1 GHz, input power: 15 dBm) of the produced evaluation sample 100C were measured.

[result]
FIG. 5 shows the 2HD characteristic evaluation results of the evaluation sample 100A produced in Example 1 and the evaluation sample 100C produced in Comparative Example 1. In FIG. 5, "No EB" is the result of the evaluation sample 100C of Comparative Example 1, and the plot where the EB irradiation amount is 1×10 ¹⁴ to 1×10 ¹⁶ /cm ² is the result for evaluation of Example 1. These are the results for sample 100A. Moreover, in FIG. 5, the results are shown for each resistivity of the supporting substrate used.

From the results of Comparative Example 1 shown in FIG. 5, it can be seen that the 2HD characteristics depend on the resistivity of the supporting substrate and are larger than when EB irradiation is performed.

On the other hand, from the results shown in FIG. 5, the 2HD characteristics depend on the resistivity of the support substrate 1 and the amount of electron beam irradiation, but even if the support substrate has the same resistivity, the comparative example It can be seen that the 2HD characteristics were significantly improved compared to 1.

This result shows that by forming a high-frequency element on the SOI layer of an SOI substrate and then irradiating the surface of the SOI layer with an electron beam, the high-frequency characteristics of the formed high-frequency element can be improved.

Although not shown in FIG. 5, the 2HD characteristic evaluation results of the evaluation sample 100B produced in Example 2 were similar to the results of the evaluation sample 100A of Example 1. In other words, even in Example 2, the 2HD characteristics depended on the resistivity of the support substrate 1 and the amount of electron beam irradiation, but even with the support substrates having the same resistivity, the 2HD characteristics were lower than those in Comparative Example 1 by electron beam irradiation. We were able to greatly improve the characteristics.

From this result, it can be seen that even if the surface of the SOI layer is irradiated with an electron beam before forming the high-frequency device on the SOI layer of the SOI substrate, the high-frequency characteristics of the high-frequency device to be formed can be improved.

In Example 2, electron beam irradiation was performed before forming the CPW, but if heat treatment is not performed to recover defects formed by electron beam irradiation, for example, electron beam irradiation may be used for bonding in the SOI substrate manufacturing process. Similar effects can be obtained even if the process is performed after the heat treatment process or before the SOI layer removal process.

Note that the present invention is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any embodiment that has substantially the same configuration as the technical idea stated in the claims of the present invention and has similar effects is the present invention. covered within the technical scope of.

1...Silicon single crystal substrate (supporting substrate), 2...Substrate to become SOI layer (silicon single crystal layer), 3...Charge trapping layer (polysilicon (Poly-Si) layer), 4...Buried insulating layer (BOX layer; 5... CPW (Al electrode), 10... Semiconductor substrate, 10A... First composite body, 10B... Second composite body, 10C... Substrate, 12... High frequency element forming part, 12a... Active element forming part, 12b...Passive element formation part, 20, 20'...High frequency element, 20a...Active element, 20b...Passive element, 20b-1...Element, 20b-2...Wiring, 50a...Metal electrode, 50b...Central metal electrode, 50c... Electric field, 50d...Magnetic field, 100...High frequency semiconductor device, 100A, 100B and 100C...Evaluation sample.

Claims (8)

A method for manufacturing a high-frequency semiconductor device used in a high-frequency region, comprising a semiconductor substrate and a high-frequency element formed on the semiconductor substrate, the method comprising:
preparing the semiconductor substrate containing a dopant;
A method for manufacturing a high-frequency semiconductor device, comprising the step of inactivating the dopant in the semiconductor substrate by irradiating at least a high-frequency element forming portion of the semiconductor substrate with a particle beam. 2. The method of manufacturing a high frequency semiconductor device according to claim 1, wherein the semiconductor substrate includes a silicon single crystal substrate having a resistivity of 500 Ω·cm or more. 3. Before forming the high-frequency element on the semiconductor substrate, at least the high-frequency element forming portion of the semiconductor substrate where the high-frequency element is formed is irradiated with the particle beam. A method for manufacturing a high frequency semiconductor device according to. According to claim 1 or 2, after forming the high frequency element on the semiconductor substrate, the particle beam is irradiated to at least the high frequency element forming portion of the semiconductor substrate in which the high frequency element is formed. A method of manufacturing the high frequency semiconductor device described above. 5. The method for manufacturing a high-frequency semiconductor device according to claim 4, wherein an electron beam is irradiated as the particle beam. The semiconductor substrate is an SOI substrate,
silicon single crystal substrate,
embedded insulating layer,
A claim characterized in that an SOI substrate is used, comprising: a charge trapping layer as an intermediate layer formed between the silicon single crystal substrate and the buried insulating layer; and an SOI layer disposed on the buried insulating layer. A method for manufacturing a high frequency semiconductor device according to any one of claims 1 to 5. A high frequency semiconductor device used in a high frequency region, comprising a semiconductor substrate and a high frequency element formed on the semiconductor substrate,
The semiconductor substrate contains a dopant,
A high-frequency semiconductor device, wherein the dopant in the semiconductor substrate is inactivated at least in a high-frequency element formation portion in which the high-frequency element is formed. The semiconductor substrate is an SOI substrate,
silicon single crystal substrate,
embedded insulating layer,
Claim characterized in that the SOI substrate comprises: a charge trapping layer as an intermediate layer formed between the silicon single crystal substrate and the buried insulating layer; and an SOI layer disposed on the buried insulating layer. 7. The high frequency semiconductor device according to 7.

Images