CN108109895B - Needle-shaped test piece, preparation method and analysis method thereof - Google Patents

Abstract

The present invention relates to a needle-shaped test piece, a preparation method thereof and an analysis method thereof. The needle-shaped test piece comprises a substrate, a component layer and a heat dissipation layer. The component layer is arranged on the substrate and includes an area of interest. The heat dissipation layer covers the exposed surfaces of the substrate and the component layer, and the thermal conductivity of the heat dissipation layer is greater than the thermal conductivity of the substrate.

Description

Needle-shaped test piece, its preparation method and its analysis method

technical field

The embodiments of the present invention relate to a test piece, its preparation method and its analysis method, in particular to a needle-shaped test piece, its preparation method and its analysis method.

Background technique

Generally, in order to analyze the material composition of a semiconductor device, an atom probe technology is used to analyze a test piece prepared from the semiconductor device. Atom probe technology is to heat and provide an electric field to a test piece of materials including metals and semiconductors, so that ions are incident from the surface of the test piece to a mass spectrometer, and then the ion species is identified by measuring the time required for ion incidence and the charge. Current methods used to increase the resolution of mass spectrometry have the disadvantages of being time-consuming and increasing costs. Therefore, increasing the resolution of mass spectrometry is still a problem to be solved in this field.

Contents of the invention

According to an embodiment of the present invention, the needle-shaped test piece includes a substrate, a component layer, and a heat dissipation layer. A component layer is disposed on the substrate, including the region of interest. The heat dissipation layer covers the exposed surfaces of the substrate and the component layer, and the thermal conductivity of the heat dissipation layer is greater than that of the substrate.

According to an embodiment of the present invention, the preparation method of the needle-shaped test piece includes the following steps. Part of the semiconductor device is cut to form a needle-shaped test piece, the needle-shaped test piece includes a part of the substrate and a part of the component layer containing the region of interest. A heat dissipation layer is formed on the exposed surface of the needle-shaped test piece, and the thermal conductivity of the heat dissipation layer is greater than that of the substrate.

According to an embodiment of the present invention, the analysis method of the needle-shaped test piece includes the following steps. Provide a needle-shaped test piece, which includes a substrate, a component layer, and a heat dissipation layer, wherein the component layer is disposed on the substrate and includes an area of interest, the heat dissipation layer covers the exposed surfaces of the substrate and the component layer, and the thermal conductivity of the heat dissipation layer greater than the thermal conductivity of the substrate. Atom probe techniques are performed on needle-shaped coupons to analyze the atomic composition in a region of interest.

Description of drawings

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain principles of the invention.

Fig. 1 is the flowchart of the preparation method of the needle test piece according to some embodiments of the present invention;

2A to 2C are schematic flow charts of a method for preparing a needle-shaped test piece according to some embodiments of the present invention;

Fig. 3 is a flow chart of the analysis method of the needle-shaped test piece according to some embodiments of the present invention;

Figure 4 is a schematic diagram of an atom probe technology device according to some embodiments of the invention.

Detailed ways

The following disclosure provides many different embodiments or examples for implementing different features of the provided object. Specific examples of components and arrangements are described below for the purpose of conveying the present invention in a simplified form. Of course, these are examples only and not limiting. For example, in the following description, forming a first feature over or on a second feature may include embodiments where the first feature is formed in direct contact with the second feature, and may also include embodiments where the first feature is in direct contact with the second feature. An additional feature may be formed between two features such that the first feature may not be in direct contact with the second feature. Additionally, the present invention may reuse component symbols and/or letters in various instances. Reuse of reference symbols is for simplicity and clarity and does not imply a relationship between the various embodiments and/or configurations being discussed per se.

In addition, in order to easily describe the relationship between one component or feature and another component or feature shown in the drawings, for example, "under", "below", "lower part", "under" may be used herein. Spatially relative terms for "on", "above", "upper" and similar terms. The spatially relative terms are intended to encompass different orientations of components in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein interpreted accordingly.

Fig. 1 is a flowchart of a method for preparing a needle-shaped test piece according to some embodiments of the present invention. 2A to 2C are schematic flowcharts of a method for preparing a needle-shaped test piece according to some embodiments of the present invention.

Please refer to FIG. 1 and FIG. 2A at the same time. First, step S10 is performed to cut a part of the semiconductor device (not shown) to form acicular test piece 102. Partial component layer 106 . In some embodiments, the semiconductor device is, for example, a wafer, which includes transistors, resistors, diodes, photodiodes, or fuse components. The semiconductor device includes a substrate 104 and a component layer 106 disposed in or on the substrate 104 . The component layer 106 includes a region of interest 110 . Taking a semiconductor device including a fin field effect transistor as an example, the component layer 106 may be components of a fin transistor such as a fin, a channel, a gate, a source and a drain, and a dielectric layer, but the present invention does not take this as an example limit. In some embodiments, the substrate 104 includes, for example, bulk silicon, a doped or undoped silicon substrate, a silicon-on-insulator (SOI) substrate, or a silicon-on-sapphire (SOS) substrate. Of course, in some embodiments, the substrate 104 may also include a suitable elemental semiconductor such as germanium or diamond, a suitable compound semiconductor such as silicon carbide, gallium nitride, gallium arsenide or indium phosphide, or a suitable compound semiconductor such as germanium silicide, indium silicide, Suitable alloy semiconductors such as aluminum gallium arsenide or phosphorous gallium arsenide. In general, the component layer 106 includes a conductor layer and a dielectric layer. The material of the conductor layer includes metal, doped silicon or polysilicon and the like. The material of the dielectric layer includes oxide or nitride, such as silicon oxide, silicon nitride, titanium nitride, tantalum nitride, titanium aluminum carbide, and the like.

In some embodiments, the method of cutting the semiconductor device includes using a focused ion beam (Focused Ion Beam, FIB), an electrochemical method, or any method capable of producing needle-shaped cross-sections. The focused ion beam method is implemented, for example, by partially sputtering a focused ion beam on the surface layer of a semiconductor device. For example, during ion beam ablation, semiconductor devices are selectively etched by injecting a focused ion beam, mainly gallium ions, onto the surface of the semiconductor device. Wherein, the vacuum pressure in the chamber for generating the focused ion beam is maintained at about 7 microtorr to 10 microtorr. In this way, the focused ion beam can strike the surface of the semiconductor device at a very small angle, such as 0° to 5°, to obtain the needle-shaped test piece 102 .

Macroscopically speaking, the shape of the needle-shaped test piece 102 after step S10 is, for example, approximately a cone (as shown in FIG. 2A ). In some embodiments, the apex angle θ of the cone 102 is about 12 degrees to 24 degrees. However, microscopically, the needle-shaped test piece 102 is substantially a cone with an arc-shaped top 102a. In some embodiments, the curved top 102a is, for example, a hemispherical top. In some embodiments, the diameter d of the arc-shaped top 102 a of the needle test strip 102 is about 7 nm to 13 nm. In some embodiments, the diameter d of the region of interest 110 is about 40 nm to 60 nm. In some embodiments, the vertical distance h between the top 102 a of the needle test strip 102 and the region of interest 110 is about 50 nm to 150 nm. In some embodiments, the vertical height of the needle test strip 102 is, for example, about 5 microns to 15 microns. In some embodiments, since the substrate 104 accounts for the largest proportion of the needle strip 102 , the overall properties of the needle strip 102 are still most related to the material of the substrate 104 .

Please refer to FIG. 1 and FIG. 2B at the same time. Next, step S20 is performed to form a heat dissipation layer 120 on the exposed surface of the needle-shaped test piece 102 . The thermal conductivity of the heat dissipation layer 120 is greater than that of the substrate 104 . The heat dissipation layer 120 is, for example, coated on the entire exposed surface of the needle test piece 102 , that is, coated on the side surface of the substrate 104 and the top surface of the side surface of the component layer 106 . In some embodiments, the substrate 104 is, for example, a silicon substrate, and its thermal conductivity is, for example, 4 Watt·m ⁻¹ ·Kelvin ⁻¹ . In some embodiments, the thermal conductivity of the heat dissipation layer 120 is about 10 Watt·m ⁻¹ ·Kelvin ⁻¹ to 2300 Watt·m ⁻¹ ·Kelvin ⁻¹ . For example, the material of the heat dissipation layer 120 is metal, including copper, gold, aluminum or silver. In some embodiments, the material of the heat dissipation layer 120 should avoid mass interference with the needle-shaped test piece 102 to be analyzed, and the difference between the volatile electric field and the surface substance of the needle-shaped test piece 102 should not be too large. In some embodiments, the ratio of the thickness of the heat dissipation layer 120 to the thickness of the region of interest 110 is about 1:1 to 1:3. In some embodiments, the thickness of the heat dissipation layer 120 at the side of the needle-shaped test piece 102 is, for example, 20 nm to 40 nm. In some embodiments, the thickness of the heat dissipation layer 120 located on the top of the needle-shaped test piece 102 is, for example, 30 nm to 60 nm. For example, the heat dissipation layer 120 has good adhesion to the main material of the needle test piece 102 (such as silicon). In some embodiments, the heat dissipation layer 120 is made of a single conductive material, but the invention is not limited thereto. In some embodiments, the heat dissipation layer 120 is, for example, conformally formed on the exposed surface of the needle test strip 102 . In some embodiments, the method for forming the heat dissipation layer 120 is, for example, a deposition process or a coating process, etc., wherein the deposition process includes a physical vapor deposition process, a chemical vapor deposition process, or a chemical deposition process, etc., and the coating process includes a spin coating process, etc. .

In some embodiments, the deposition process is used to form the heat dissipation layer 120 as an example. For example, the needle-shaped test piece 102 is placed in the ion beam sputtering machine 200 to deposit the heat dissipation layer 120 . In detail, the ion beam sputtering machine 200 includes, for example, a first ion gun 202 , a second ion gun 204 , a target 206 and a stage 208 . Wherein, the first ion gun 202 and the second ion gun 204 are arranged opposite to each other, the first ion gun 202 can also be called an upper ion gun, and the second ion gun 204 can also be called a lower ion gun. The target 206 is a material for forming the heat dissipation layer 120 , such as a metal target such as copper, gold, aluminum or silver, which is disposed between the first ion gun 202 and the second ion gun 204 . The platform 208 is used to carry the needle-shaped test piece 102 and fix the needle-shaped test piece 102 thereon, and the platform 208 itself can be rotated and tilted. In the embodiment shown in FIG. 2B , it is taken as an example to show that the stage 208 carries a needle-shaped test piece 102 , but the present invention is not limited thereto. In some embodiments (not shown), the stage 208 includes, for example, a base and at least one sub-stage disposed on the base, wherein the sub-stage (coupon) accommodates the needle-shaped test strip 102 . That is to say, the number of acicular test pieces 102 that can be carried by the carrier 208 is determined by the number of sub-carriers. In some embodiments (not shown), the sub-stage may include grooves such that a portion of the needle-shaped test strip 102 is seated in the grooves to secure it.

In some embodiments, firstly, the needle test strip 102 is fixed on the stage 208 . Next, the atoms 206 a or clusters of the target 206 are deposited forward on the needle-shaped test piece 102 in such a way that the needle-shaped test piece 102 faces the target 206 . Among them, the needle-shaped test piece 102 is rotated by the rotation of the stage 208 . In some embodiments, the rotation angle of the stage 208 is, for example, 20 rpm to 40 rpm. Then, on the position of multiple inclined angles of the stage 208 , in the manner that the atoms 206 a or clusters of the target 206 are inclined to the needle-shaped test piece 102 , the needle-shaped test piece 102 is respectively subjected to oblique-angle deposition. Wherein, the needle-shaped test piece 102 can be moved by moving the position of the stage 208 . In some embodiments, based on the horizontal axis HA, the inclination angle α of the stage 208 is, for example, -40 degrees to +40 degrees or -80 degrees to +80 degrees. In detail, when a bias voltage is applied to the first ion gun 202 and the second ion gun 204, the first ion gun 202 and the second ion gun 204 will accelerate the ions to hit the target 206, so that the atoms 206a or clusters that are knocked out Clusters are deposited on the needle test strip 102 . In some embodiments, the current intensity of the ion beam 205 striking the target 206 is, for example, 30 mA to 90 mA. In some embodiments, since the needle-shaped test piece 102 will rotate and tilt along with the stage 208, the heat dissipation layer 120 can be uniformly formed on the needle-shaped test piece 102 to completely cover the exposed surface of the needle-shaped test piece 102. surface. Although in this embodiment, the machine for deposition is an ion beam sputtering machine for illustration, the present invention is not limited thereto. In other embodiments, other machines capable of performing a deposition process or a coating process may also be used.

Please refer to FIG. 2C , and then, a needle-shaped test piece 100 is obtained. In some embodiments, the acicular test strip 100 includes local semiconductor devices, such as nanoscale fin transistors and the like. The needle test strip 100 includes a substrate 104 , a component layer 106 and a heat dissipation layer 120 . The component layer 106 is disposed on the substrate 104 and includes a region of interest 110 . The heat dissipation layer 120 covers the exposed surfaces of the substrate 104 and the component layer 106 , and the thermal conductivity of the heat dissipation layer 120 is greater than that of the substrate 104 .

In some embodiments, when there are defects such as depressions or cavities on the surface of the needle-shaped test piece 102, it can also be filled by the aforementioned ion beam sputtering machine 200, so that the needle-shaped test piece 100 has a substantially smooth surface. surface. Wherein, the above-mentioned depression or void may be caused by a delay process for removing semiconductor material or conductor material, so a process such as gap filling usually needs to be performed on this place. In addition, in the above-mentioned embodiments, the ion beam sputtering machine 200 is used to form a film layer on the surface of the needle-shaped test piece 102 as the heat dissipation layer 120 or the hole filling material, but in other embodiments (not shown ), if the target is not placed in the ion beam sputtering machine 200, then the ion beam sputtering machine 200 can be used to clean the surface of the test piece 102, that is to say, through the ion beam from the first ion gun 202 and the second Ions from the two ion guns 204 collide with the surface of the test piece 102 for cleaning purposes.

Fig. 3 is a flow chart of the analysis method of the needle test strip according to some embodiments of the present invention. Figure 4 is a schematic diagram of an atom probe technology device according to some embodiments of the invention. Referring to FIG. 3 , firstly, step S310 is performed to provide a needle-like test piece 100 having the aforementioned structure. In detail, the needle test strip 100 is from a part of the semiconductor device, which includes the region of interest 110 . The needle test strip 100 is used as a test strip for subsequent testing or characterization of the region of interest 110 of the semiconductor device.

Please refer to FIG. 3 , and then proceed to step S320 , performing atom probe technology on the needle-shaped test piece 100 to analyze the atomic composition in the region of interest 110 . In some embodiments, atom probe technology can provide atomic-scale stereo images and chemical material composition of the region of interest 110 . As shown in FIG. 4 , the atom probe technology device 400 includes, for example, a laser source 410 , a position sensitive detector 420 and a processing unit 430 . Firstly, the top of the needle test strip 100 is irradiated with the laser pulse 410 generated by the laser source 410 . As the top of the acicular test strip 100 is irradiated by the laser pulse 422, the atoms 412 in the acicular test strip 100 are removed (such as exfoliated) layer by layer. Then, according to the electric field generated between the position-sensitive detector 420 and the needle test strip 100 , the removed atoms 412 are projected onto the position-sensitive detector 420 . Therefore, the time between the moment when the laser is pulsed and the moment when the removed atoms 412 reach the inductive detector 420 can be used to determine the time of flight (time of flight) of the atoms 412 (ie ions) to confirm the quality. Charge ratio (ie m/q). The x,y coordinates of the detected atoms 412 on the inductive detector 420 can then be used to reconstruct the original position of the atom corresponding to the top of the needle strip 100 . Wherein, the processing unit 430 can collect the position data by the inductive detector 420 and reconstruct the stereoscopic image of the top of the needle-shaped test strip 100 according to the atomic species.

In some embodiments, the outer layer of the needle-shaped test piece is configured with a heat dissipation layer, and the thermal conductivity of the heat dissipation layer is greater than that of the main body of the needle-shaped test piece. Due to the good thermal conductivity of the heat dissipation layer, it is possible to avoid heat accumulation on the surface of the needle-shaped test piece during the atom probe technique, thereby preventing the generation of background noise and greatly improving the resolution of the mass spectrometer. In addition, in some embodiments, the heat dissipation layer is only composed of a single material, thus avoiding the material of the heat dissipation layer from interfering with mass spectrum resolution or increasing the additional burden of mass spectrum resolution. Furthermore, in some embodiments, the preparation method of the needle-shaped test strip is applicable to all stacks of semiconductor layers and conductor layers, and thus can be widely used in preparing test strips of various semiconductor devices. In addition, in some embodiments, the method for preparing the needle-shaped test piece has simple steps and can be achieved by using existing machines, so the method for preparing the needle-shaped test piece has the advantages of high yield and low cost.

In some embodiments, a needle coupon includes a substrate, a component layer, and a heat dissipation layer. The component layer is disposed on the substrate, including the region of interest. The heat dissipation layer covers the exposed surfaces of the substrate and the component layer, and the thermal conductivity of the heat dissipation layer is greater than that of the substrate.

In some embodiments, a method for preparing a needle test strip includes the following steps. Part of the semiconductor device is cut to form a needle-shaped test piece, the needle-shaped test piece includes a part of the substrate and a part of the component layer containing the region of interest. A heat dissipation layer is formed on the exposed surface of the needle-shaped test piece, and the thermal conductivity of the heat dissipation layer is greater than that of the substrate.

In some embodiments, a method for analyzing needle test strips includes the following steps. Provide a needle-shaped test piece, which includes a substrate, a component layer, and a heat dissipation layer, wherein the component layer is disposed on the substrate and includes an area of interest, the heat dissipation layer covers the exposed surfaces of the substrate and the component layer, and the thermal conductivity of the heat dissipation layer greater than the thermal conductivity of the substrate. Atom probe techniques are performed on needle-shaped coupons to analyze the atomic composition in a region of interest.

The features of several embodiments are outlined above, so that those skilled in the art can better understand aspects of the present invention. Those skilled in the art should understand that they can easily use the present invention as a basis for designing or modifying other processes and structures to achieve the same purpose and/or achieve the same advantages of the embodiments described herein. Those skilled in the art should also understand that this equivalent configuration does not depart from the spirit and scope of the present invention, and those skilled in the art can make various modifications herein without departing from the spirit and scope of the present invention. Alter, replace, and change.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some changes and modifications without departing from the spirit and scope of the present invention. within the scope of the present invention.

Claims (10)

1. a needle-shaped test piece, is characterized in that, comprises: Substrate; a component layer, disposed on the substrate, including a region of interest; and A heat dissipation layer completely covers the surface of the substrate and the component layer including the region of interest, and the thermal conductivity of the heat dissipation layer is greater than the thermal conductivity of the substrate. 2 . The needle-shaped test piece according to claim 1 , wherein the heat dissipation layer has a thermal conductivity of 10 watt·m ⁻¹ ·Kelvin ⁻¹ to 2300 watt·m ⁻¹ ·Kelvin ⁻¹ . 3. The needle test piece according to claim 1, wherein the heat dissipation layer comprises copper, gold, aluminum or silver. 4. The needle-shaped test piece according to claim 1, wherein the diameter of the arc-shaped top of the needle-shaped test piece is 7 nm to 13 nm. 5. The acicular test piece according to claim 1, wherein the apex angle of the acicular test piece is 12° to 24°. 6 . The needle-shaped test piece according to claim 1 , wherein the vertical distance between the top of the needle-shaped test piece and the region of interest is 50 nm to 150 nm. 7. A preparation method of needle-shaped test piece, characterized in that, comprising: cutting a portion of the semiconductor device to form a needle-shaped test strip including a portion of the substrate and a portion of the component layer containing the region of interest; and A heat dissipation layer is formed on the exposed surface of the needle-shaped test piece, and the thermal conductivity of the heat dissipation layer is greater than that of the substrate. 8 . The method for preparing the needle-shaped test piece according to claim 7 , wherein the method of cutting a part of the semiconductor device includes using a focused ion beam method or an electrochemical method. 9 . The method for preparing the needle-shaped test piece according to claim 7 , wherein the method of forming the heat dissipation layer comprises a deposition process or a coating process. 10. An analytical method for a needle-shaped test piece, characterized in that it comprises: A needle-shaped test piece is provided, which includes a substrate, a component layer, and a heat dissipation layer, wherein the component layer is configured on the substrate and includes a region of interest, and the heat dissipation layer completely covers the substrate and includes the sensor layer. the surface of the component layer in the region of interest, and the thermal conductivity of the heat dissipation layer is greater than the thermal conductivity of the substrate; and The atom probe technique is performed on the needle strip to analyze the atomic composition in the region of interest.