Focused ion beam systems for large area substrates

Abstract

A method and apparatus for cutting electronic devices are disclosed. In one embodiment, an apparatus for cutting electronic devices on a substrate is described, the apparatus comprising a platform for supporting the substrate having the electronic devices thereon; a focused ion beam column fixed in position above the platform, the focused ion beam column adapted to emit a beam path at an acute angle relative to a plane of a major surface of the substrate; and a microscope positioned adjacent to the focused ion beam column, wherein the platform is constrained to move in an X-Y plane during cutting of the electronic devices.

Description

[0001] background

[0002] field

[0003] Embodiments of the present disclosure generally relate to a focused ion beam system for analyzing electronic devices on a large area substrate, and more particularly to a method and apparatus for analyzing thin film transistors (TFTs) on a large area substrate on which a plurality of TFTs are formed.

[0004] Description of related technologies

[0005] Electronic devices, such as thin film transistors, photovoltaic (PV) devices, or solar cells, and other electronic devices, have been manufactured on large area substrates (e.g., thin, flexible dielectrics) for many years. The substrates may be made of glass, polymers, or other materials suitable for forming electronic devices. There are ongoing efforts to manufacture electronic devices on substrates with surface areas much larger than one square meter (e.g., two square meters or more) to produce larger sizes of final products and / or to reduce the manufacturing cost of each device (e.g., pixel, TFT, photovoltaic or solar cell, etc.).

[0006] It is often necessary to analyze discrete devices, such as thin film TFTs, that have been determined to be defective. For example, the transistor that switches an individual pixel may be defective, causing the pixel to always be in the on state, or always be in the off state.

[0007] Focused ion beam (FIB) system has been used as an analytical technique in the semiconductor industry, materials science, and increasingly in the biological field. In the semiconductor industry, the FIB system uses an ion beam to perform a specific site (site-specific) analysis on a part of a bare chip (die) on a wafer (wafer), such as a "sample". The wafer (with a sample on the wafer) is attached to a movable platform. This platform is usually used to tilt and / or rotate this platform so that the major surface of this platform is at an angle of about 45 degrees relative to a horizontal plane (such as a plane of a manufacturing facility floor). The ions from the FIB system usually cut a two-dimensional rectangular shape in the sample, wherein the region of interest is angled relative to the major surface of the wafer. Then, a scanning electron microscope (SEM) is used to analyze the region of interest.

[0008] However, large-area substrates used for TFT fabrication are highly flexible at room temperature, which presents processing challenges that preclude the use of conventional FIB systems and methods.

[0009] There is a need for a method and apparatus that can utilize FIB technology for large area substrates.

[0010] Overview

[0011] A method and apparatus for cutting electronic devices are disclosed. In one embodiment, an apparatus for cutting electronic devices on a substrate is described, the apparatus comprising a stage for supporting a substrate having electronic devices on the substrate; a focused ion beam column fixed in position above the stage, the focused ion beam column adapted to emit a beam path at an acute angle relative to a plane of a major surface of the substrate, and a microscope positioned adjacent to the focused ion beam column, wherein the stage is constrained to move in an XY plane during cutting of the electronic devices.

[0012] In another embodiment, an apparatus for cutting electronic devices on a substrate is disclosed. The apparatus includes a stage for supporting a substrate having an electronic device on the substrate; a focused ion beam column fixed in position above the stage, the focused ion beam column adapted to emit a beam path and cut a three-dimensional notch in the electronic device; and a microscope positioned adjacent to the focused ion beam column, wherein the stage is constrained to move in an XY plane during cutting of the electronic device.

[0013] In another embodiment, a method for cutting an electronic device on a substrate is disclosed. The method includes positioning the substrate on a platform; emitting a beam path from a focused ion beam column, the focused ion beam column being fixed at an angle of about 45 degrees relative to a major surface of the substrate; and moving the platform in a single lateral plane to create a three-dimensional recess in the electronic device.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to be able to understand the above-mentioned features of the present disclosure in detail, a more detailed description of the present disclosure briefly summarized above can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate exemplary embodiments and are therefore not to be considered as limiting the scope of the present disclosure, which may allow other equivalent embodiments.

[0016] Figure 1A is a schematic cross-sectional view of one embodiment of a focused ion beam system.

[0017] Figure 1B yes Figure 1A Another schematic cross-sectional view of a focused ion beam system.

[0018] 2A-2B depict electronic devices cut by conventional methods.

[0019] Figure 3A-3C are various views of an electronic device cut through by the methods and apparatus as disclosed herein.

[0020] Figure 4 is a schematic cross-sectional view of the metering system.

[0021] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.

[0022] Specific instructions

[0023] The present disclosure generally relates to a focused ion beam (FIB) system for analyzing electronic devices on large area substrates. As used herein, the large area substrate includes a major surface having a surface area greater than one square meter, such as two square meters or greater. Exemplarily, the FIB system as described herein is disclosed as being used to analyze thin film transistors (TFTs) on large area substrates. However, the FIB system and method as described herein can be used to analyze other electronic devices on large area substrates.

[0024] Figure 1A is a schematic cross-sectional view of one embodiment of a focused ion beam (FIB) system 100 . Figure 1B yes Figure 1A Another schematic cross-sectional view of a FIB system 100 . Figure 1A The FIB system 100 shown in FIG. 1 is performing a sawing process 105A in which a large area substrate 110 is sawed (the large area substrate 110 having transistors 115 thereon). Figure 1B The FIB system 100 shown in FIG. 1 is executing an analysis mode 105B in which a cut transistor 115 is analyzed.

[0025] The large area substrate 110 is positioned on a stage 120. The stage 120 has a major surface 125 that supports the large area substrate 110 in an orientation where the plane of the major surface 125 is parallel to the Y direction.

[0026] The platform 120 is movable at least in a lateral direction (in the X direction and / or the Y direction). The platform 120 supports the large area substrate 110 so that the major surface 130 of the large area substrate 110 is parallel to the major surface 125 of the platform 120. Therefore, the plane 135 of the major surface 130 of the large area substrate 110 is parallel to the Y direction.

[0027] The FIB system 100 also includes a focused ion beam (FIB) column 140 that emits an ion beam. The FIB column 140 is supported so that a beam path 145 of the FIB column 140 is oriented at an angle α relative to a plane 135 of the major surface 130 of the large area substrate 110. The angle α of the beam path 145 relative to the plane 135 of the major surface 130 of the large area substrate 110 is an acute angle, such as about 40 degrees to about 50 degrees. In one example, the angle α is about 45 degrees relative to the plane 135 of the major surface 130 of the large area substrate 110.

[0028] The beam path 145 of the FIB column 140 is configured to cut a three-dimensional space 150 in the transistor 115 and / or the large area substrate 110. The three-dimensional space 150 is formed by moving the stage 120 laterally (in the X and Y directions) relative to the FIB column 140, the stage 120 having the large area substrate 110. The three-dimensional space 150 is cut in one plane (the XY plane).

[0029] The FIB system 100 also includes a microscope 155. Figure 1B As shown in FIG. 1 , a microscope 155 is used to analyze the three-dimensional space 150 of the transistor 115. The microscope 155 may be a scanning electron microscope having an observation path 160. The observation path 160 is oriented at an angle normal to the plane 135 of the major surface 130 of the large area substrate 110.

[0030] In executing Figure 1A After the cutting process 105A shown and described in FIG. 1 , the platform 120 is moved in the Y direction so that the three-dimensional space 150 of the transistor 115 is located under the microscope 155, as shown in FIG. Figure 1B . In the analysis process 105B, the platform 120 can be moved laterally so that the observation path 160 of the microscope 155 scans the three-dimensional space 150. In the three-dimensional space 150, the cross-section of the transistor 115 is visible to the microscope 155. For example, the source and drain regions, and the active layer, and the cross-section of the large area substrate 110 are visible to the microscope 155. During the cutting process 105A, the movement of the platform 120 can be limited to movement in the XY plane.

[0031] 2A-2B depict an electronic device 200 cut by a conventional method. The conventional method tilts and / or rotates an underlying substrate (not shown) with the electronic device 200 on the substrate relative to a horizontal plane on a platform (not shown). The electronic device 200 is also rotated and / or tilted relative to a fixed FIB column (not shown). The FIB column cuts the electronic device 200 to produce a two-dimensional recess 205. During this cutting, the beam path (not shown) of the FIB column is angled up to about 90 degrees relative to the major surface of the electronic device 200.

[0032] The two-dimensional recess 205 is more clearly seen in the cross-sectional view of FIG. 2B . The two-dimensional recess 205 includes a wall 210 on each side of an angled surface 215. The angled surface 215 is a plane that is usually observed by a microscope (not shown). The surface roughness (average surface roughness (average surface roughness, Ra)) of the wall 210 has a higher surface roughness because the wall 210 is not parallel to the FIB scanning direction, but is defined by the position where the scan starts and the scan ends. The angled surface 215 roughness Ra can be about 5 nanometers to about 10 nanometers or more. The wall 210 is at a 90-degree angle relative to the main surface of the electronic device 200, and due to the steep (steep) viewing angle, these walls 210 can be observed by a microscope with reduced resolution or image quality. Therefore, the angled surface 215 is the only plane that can be observed with full microscope resolution and lower surface roughness.

[0033] Figure 3A-3C are various views of an electronic device 200 cut by the methods and apparatus as disclosed herein. Figure 1A An apparatus for cutting an electronic device 200 is shown in FIG.

[0034] According to the embodiments described herein, the method of cutting the electronic device 200 generates a three-dimensional notch 300. The three-dimensional notch 300 and Figure 1A and Figure 1B 3D recess 300 is the same as the three-dimensional space 150 shown in . The three-dimensional recess 300 includes a plurality of angled surfaces, such as a first angled surface 305 and a second angled surface 310. The first angled surface 305 and the second angled surface 310 are planes observed by a microscope (not shown). The first angled surface 305 and the second angled surface 310 may be adjacent to each other. In addition, the three-dimensional recess 300 includes a single wall 315.

[0035] Each of the first angled surface 305 and the second angled surface 310 includes an angle 320. The angle 320 of both the first angled surface 305 and the second angled surface 310 can be the same. The angle 320 can be about 45 degrees. The single wall 315 can be at an angle of about 90 degrees relative to the major surface of the electronic device 200 and cannot be observed through a microscope. The roughness (Ra) of the first angled surface 305 and the second angled surface 310 can be about 2 nanometers to about 0.1 nanometers or less.

[0036] Figure 4 4 is a schematic cross-sectional view of a metering system 400. The metering system 400 includes a vacuum chamber 405 having a Figure 1A and Figure 1B The platform 120 described in the foregoing. The platform 120 supports the large area substrate 110, which has an electronic device (not shown) thereon. The vacuum chamber 405 is fluidly coupled to a vacuum pump 410, which maintains a negative pressure in the vacuum chamber 405.

[0037] The FIB column 140 and the microscope 155 are at least partially positioned in a vacuum chamber 405 above the platform 120. The metrology system 400 also includes an auxiliary electron detector 415. The auxiliary electron detector 415 is used for imaging during the cutting of electronic devices using the FIB column 140.

[0038] The methods and apparatus described herein can cut electronic devices without tilting and / or rotating the electronic device and the underlying substrate. The methods and apparatus described herein also produce multiple surfaces that can be observed by a microscope. The three-dimensional recess 300 as disclosed herein allows the cross-section of a portion of the source and drain regions, and the active layer, and the underlying substrate to be observed in three dimensions.

[0039] Further numbered implementations are as follows.

[0040] According to embodiment 1, there is provided an apparatus for cutting an electronic device on a substrate, the apparatus comprising: a platform for supporting the substrate having the electronic device on the substrate; a focused ion beam column fixed in a position above the platform, the focused ion beam column being adapted to emit a beam path at an acute angle relative to a plane of a major surface of the substrate; and a microscope positioned adjacent to the focused ion beam column, wherein the platform is movable in an XY plane during cutting of the electronic device.

[0041] According to embodiment 2, the apparatus according to embodiment 1 is provided, wherein the beam path cuts a three-dimensional notch in the electronic device.

[0042] According to embodiment 3, there is provided a device according to embodiment 2, wherein the three-dimensional recess comprises a plurality of angled surfaces observable through the microscope.

[0043] According to embodiment 4, the apparatus according to embodiment 3 is provided, wherein each of the plurality of angled surfaces is approximately 45 degrees relative to the plane of the major surface of the substrate.

[0044] According to embodiment 5, there is provided a device according to any one of embodiments 2 to 4, wherein the three-dimensional recess comprises a single wall that is not observable through the microscope.

[0045] According to embodiment 6, the apparatus according to embodiment 5 is provided, wherein the single wall is angled at approximately 90 degrees relative to the plane of the major surface of the substrate.

[0046] According to embodiment 7, there is provided an apparatus according to any one of embodiments 1 to 6, wherein the microscope has a viewing path oriented at approximately 90 degrees relative to the plane of the major surface of the substrate.

[0047] According to embodiment 8, there is provided an apparatus for cutting an electronic device on a substrate, the apparatus comprising: a platform for supporting the substrate having the electronic device on the substrate; a focused ion beam column fixed in a position above the platform, the focused ion beam column being suitable for emitting a beam path and cutting a three-dimensional recess in the electronic device; and a microscope positioned adjacent to the focused ion beam column, wherein the platform is constrained to move in an XY plane during cutting of the electronic device.

[0048] According to embodiment 9, there is provided an apparatus according to embodiment 8, wherein the microscope has a viewing path oriented at approximately 90 degrees relative to the plane of the major surface of the substrate.

[0049] According to embodiment 10, there is provided an apparatus according to any one of embodiments 8 to 9, wherein the beam path is fixed at an acute angle relative to the plane of the major surface of the substrate.

[0050] According to embodiment 11, there is provided a device according to any one of embodiments 8 to 10, wherein the three-dimensional recess comprises a plurality of angled surfaces that can be viewed through the microscope.

[0051] According to embodiment 12, the apparatus according to embodiment 11 is provided, wherein each of the plurality of angled surfaces is approximately 45 degrees relative to the plane of the major surface of the substrate.

[0052] According to embodiment 13, there is provided a device according to any one of embodiments 8 to 12, wherein the three-dimensional recess comprises a single wall that is not observable through the microscope.

[0053] According to embodiment 14, the apparatus according to embodiment 13 is provided, wherein the single wall is angled at approximately 90 degrees relative to the plane of the major surface of the substrate.

[0054] According to embodiment 15, the apparatus according to any one of embodiments 8 to 14 is provided, wherein the electronic device is a transistor.

[0055] In accordance with embodiment 16, a method for cutting an electronic device on a substrate is provided, the method comprising: positioning the substrate on a platform; emitting a beam path from a focused ion beam column, the focused ion beam column being fixed at an angle of approximately 45 degrees relative to a major surface of the substrate; and moving the platform in a single lateral plane to produce a three-dimensional recess in the electronic device.

[0056] According to embodiment 17, the method according to embodiment 16 is provided, further comprising: moving the platform in the single lateral plane adjacent to a microscope.

[0057] According to embodiment 18, the method according to embodiment 17 is provided, further comprising using the microscope to observe multiple angled surfaces in the three-dimensional recess.

[0058] According to embodiment 19, the method according to embodiment 18 is provided, wherein each of the plurality of angled surfaces is at an angle of approximately 45 degrees relative to the plane of the major surface of the substrate.

[0059] According to embodiment 20, a method according to any one of embodiments 17 to 19 is provided, wherein the microscope has a viewing path at an angle of approximately 90 degrees relative to the plane of the major surface of the substrate.

[0060] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments may be devised without departing from the basic scope of the present disclosure, the scope of which is to be determined by the claims that follow.

Claims

1. An apparatus for cutting electronic devices on a substrate, the apparatus comprising: a platform for supporting the substrate having the electronic device thereon; a focused ion beam column fixed in position above the platform, the focused ion beam column adapted to emit a beam path at an acute angle relative to a plane of a major surface of the substrate; and a microscope positioned adjacent to the focused ion beam column, wherein The beam path cuts a three-dimensional recess in the electronic device, the three-dimensional recess comprising a plurality of angled surfaces observable through the microscope, the platform being movable in an XY plane during cutting of the electronic device, and the electronic device being cut without tilting or rotating the electronic device and the underlying substrate.

2. The apparatus of claim 1, wherein each of the plurality of angled surfaces is 45 degrees relative to the plane of the major surface of the substrate.

3. The apparatus of claim 1, wherein the three-dimensional recess comprises a single wall that is not observable through the microscope.

4. The apparatus of claim 3, wherein the single wall is angled 90 degrees relative to the plane of the major surface of the substrate.

5. The apparatus of any one of claims 1 to 4, wherein the microscope has a viewing path oriented at 90 degrees relative to the plane of the major surface of the substrate.

6. An apparatus for cutting electronic devices on a substrate, the apparatus comprising: a platform for supporting the substrate having the electronic device thereon; a focused ion beam column fixed in position above the platform, the focused ion beam column adapted to emit a beam path and cut a three-dimensional recess in the electronic device; and a microscope positioned adjacent to the focused ion beam column, wherein the stage is constrained to move in an XY plane during cutting of the electronic device, wherein The three-dimensional recess includes a plurality of angled surfaces that are viewable through the microscope and cuts the electronic device without tilting or rotating the electronic device and the underlying substrate.

7. The apparatus of claim 6, wherein the microscope has a viewing path oriented at 90 degrees relative to the plane of the major surface of the substrate.

8. Apparatus as claimed in any one of claims 6 to 7, wherein the beam path is fixed at an acute angle relative to the plane of the major surface of the substrate.

9. The apparatus of claim 6, wherein each of the plurality of angled surfaces is 45 degrees relative to a plane of the major surface of the substrate.

10. The apparatus of claim 6, wherein the three-dimensional recess comprises a single wall that is not observable through the microscope, wherein the single wall is angled at 90 degrees relative to the plane of the major surface of the substrate.

11. The apparatus of claim 7, wherein the three-dimensional recess comprises a single wall that is not observable through the microscope, wherein the single wall is at a 90 degree angle relative to the plane of the major surface of the substrate.

12. The apparatus of any one of claims 6 to 7, wherein the electronic device is a transistor.

13. A method for cutting an electronic device on a substrate, the method comprising: supporting the substrate on a platform, the substrate having the electronic device on the substrate; securing a focused ion beam column in position above the platform; emitting a beam path through the focused ion beam column at an acute angle relative to a plane of a major surface of the substrate; During cutting of the electronic device, moving the platform in an XY plane to create a three-dimensional recess in the electronic device; and The three-dimensional recess and the microscope are positioned relative to each other for viewing the recess, wherein The three-dimensional recess includes a plurality of angled surfaces that are viewable through the microscope and cuts the electronic device without tilting or rotating the electronic device and the underlying substrate.

14. The method of claim 13, wherein the roughness (Ra) of the plurality of angled surfaces is 2 nanometers or less.

15. The method of claim 13, wherein each of the plurality of angled surfaces is at a 45 degree angle relative to the plane of the major surface of the substrate.

16. The method of claim 13, wherein the three-dimensional recess comprises a single wall that is not observable through the microscope, wherein the single wall is at a 90 degree angle relative to the plane of the major surface of the substrate.

17. The method of any one of claims 13 to 16, wherein the microscope has a viewing path at a 90 degree angle relative to the plane of the major surface of the substrate.

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