Semiconductor device inspection device and inspection method

Abstract

To provide an inspection equipment and an inspection method for semiconductor devices capable of detecting the location of defective parts with high accuracy.SOLUTION: An inspection equipment for a semiconductor device, comprises: a light source 6 that forms irradiation traces on a sample 30 by irradiating light onto the sample 30; a voltage application unit 7 that makes the irradiation traces emit light by applying voltage to the sample 30 and makes defective parts of the inspection target emit light by applying voltage to the inspection target; a first moving unit 7 that moves the inspection target; a light detection unit 9 that detects light emission from the irradiation traces; and a second moving unit 10 that moves the light detection unit 9.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an inspection device and an inspection method for a semiconductor device. [Background technology]

[0002] Conventionally, failure analysis of semiconductor devices is performed, for example, in the following manner: First, a voltage is applied to cause a defective portion on a semiconductor substrate to emit light, and the light-emitting point is detected by observing the substrate from the back side with an emission microscope. Next, the substrate is etched from the front side with a focused ion beam to roughly mark the light-emitting point.

[0003] The semiconductor device is then observed again from the back side with an emission microscope to confirm the positional relationship between the light emitting point and the marking. Based on this positional relationship, etching is performed with a focused ion beam, and a marking is placed at a position closer to the light emitting point. Based on this marking, the defective portion is cut out, and the cross section is observed.

[0004] In such a conventional method, the observation by the emission microscope and the etching by the focused ion beam are performed in separate devices, which makes it easy for the position of the light emitting point and the marking to be misaligned, making it difficult to isolate the defective portion with high accuracy.

[0005] Regarding this, for example, Patent Document 1 proposes the following inspection method for semiconductor devices such as power devices that have a characteristic pattern on the periphery: First, an electron beam and a laser beam are irradiated onto the front and back surfaces of a sample, and the amount of deviation between these optical axes and the above-mentioned pattern is confirmed by a monitor.

[0006] Next, based on this deviation, the deviation between the optical axis of the laser beam and the optical axis of the electron beam is corrected. Specifically, the deflection of the electron beam is corrected by a deflector to align the optical axis of the electron beam with the optical axis of the laser beam. Then, defective locations are detected, and the amount of shift of the detected defective locations from the optical axis of the laser beam is calculated. After that, the electron beam is scanned according to this amount of shift, and the vicinity of the defective locations is marked. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2014-143348 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the method described in Patent Document 1, the misalignment between the optical axis of the electron beam and the optical axis of the laser beam is corrected by deflecting the electron beam. However, there are cases where the optical axis of the laser beam and the optical axis of the electron beam are misaligned to such a degree that the misalignment cannot be corrected by deflecting the electron beam alone, and in such cases, it is difficult to detect the position of the defective portion with high accuracy.

[0009] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide an inspection apparatus and an inspection method for a semiconductor device that are capable of detecting the position of a defect with high accuracy. [Means for solving the problem]

[0010] In order to achieve the above object, the invention of claim 1 provides an inspection device for semiconductor devices, the inspection device comprising: a light source (6) for irradiating a sample (30) with light to form an irradiation mark on the sample; a voltage application unit (7) for applying a voltage to the sample to cause the irradiation mark to emit light and for applying a voltage to an inspection target (20) to cause a defective portion of the inspection target to emit light; a first movement unit (7) for moving the inspection target; a light detection unit (9) for detecting the light emitted from the irradiation mark; and a second movement unit (10) for moving the light detection unit. The second moving unit moves the light detection unit so that the optical axis of the light detection unit is aligned with the emitted irradiation mark, and the first moving unit moves the inspection object so that the emitted defective part is aligned with the optical axis of the light detection unit. do.

[0011] According to this, by moving the light detection unit to align the optical axis of the light detection unit with the irradiation mark on the sample, and by moving the inspection object to align the emitting part with the optical axis of the light detection unit, it is possible to align the defective part with the optical axis of the light source with high accuracy, and therefore the position of the defective part can be detected with high accuracy.

[0012] Also, claims 4 The invention described in is a method for inspecting a semiconductor device, comprising: forming an irradiation mark on a sample (30) by irradiating the sample with light; causing the irradiation mark to emit light by applying a voltage to the sample; aligning the optical axis of a light detection unit (9) with the emitted part by moving the light detection unit; causing a defective part to emit light by applying a voltage to an inspection object (20); and aligning the emitted part with the optical axis of the light detection unit by moving the inspection object.

[0013] According to this, by moving the light detection unit to align the optical axis of the light detection unit with the irradiation mark on the sample, and by moving the inspection object to align the emitting part with the optical axis of the light detection unit, it is possible to align the defective part with the optical axis of the light source with high accuracy, and therefore the position of the defective part can be detected with high accuracy.

[0014] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a configuration of an inspection device according to a first embodiment. [Diagram 2] FIG. 1 is a cross-sectional view of a semiconductor device. [Diagram 3] FIG. [Figure 4] FIG. 13 is a diagram showing how irradiation marks are formed on a sample. [Diagram 5]13 is a diagram showing how the optical axis of the light detection unit is aligned with the irradiation mark. FIG. [Figure 6] 1 is a diagram showing a state in which light from a defective portion of a semiconductor device is incident on a light detection unit; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0017] (First embodiment) A first embodiment will be described. An inspection device 1 shown in Fig. 1 is an inspection device for a semiconductor device in which a power device or the like is formed, and is used for defect analysis of the semiconductor device. As shown in Fig. 1, the inspection device 1 includes a chamber 2. The internal space of the chamber 2 is divided into two by a partition wall 3. The two spaces formed inside the chamber 2 are referred to as a first chamber 4 and a second chamber 5, respectively.

[0018] The first chamber 4 is a vacuum chamber, and the pressure in the second chamber 5 is, for example, approximately atmospheric pressure. That is, the first chamber 4 is reduced in pressure by evacuation compared to the second chamber 5. The first chamber 4 is equipped with a light source 6 and a stage 7.

[0019] The light source 6 irradiates the sample 30 described below with light to form an irradiation mark on the sample 30. The light source 6 includes an ion source that generates a Ga ion beam, an aperture, a focusing lens, an objective lens, and the like, and is configured to irradiate the sample 30 with a focused ion beam in a spot.

[0020] The stage 7 holds the sample 30 and the semiconductor device to be inspected. Note that Fig. 1 shows a state in which the sample 30 is placed on the stage 7.

[0021] The stage 7 has a function of applying a voltage to the held sample 30 and the inspection target. By applying a voltage to the sample 30, the stage 7 causes the irradiation marks formed by the irradiation of light from the light source 6 to emit light. In addition, the stage 7 applies a voltage to the inspection target to cause defective parts of the inspection target to emit light. The stage 7 corresponds to a voltage application unit.

[0022] The stage 7 also has a function of moving the inspection object held by it. Specifically, the direction perpendicular to the optical axis of the light source 6 is defined as the x direction, and the direction perpendicular to both the optical axis of the light source 6 and the x direction is defined as the y direction, and the stage 7 moves the inspection object held by it in the x direction and y direction. The stage 7 corresponds to a first moving unit.

[0023] The stage 7 is configured so that, when a voltage is applied, light generated from the sample 30 and the object to be inspected is transmitted to the second chamber 5. An opening is formed in the partition wall 3, and a vacuum window 8 is fitted into this opening. The light generated from the sample 30 and the object to be inspected is transmitted through the vacuum window 8 and enters the second chamber 5.

[0024] The second chamber 5 is provided with a light detection unit 9. The light detection unit 9 detects light emission from irradiation marks formed on the sample 30 and light emission from defective parts of the inspection target. The light detection unit 9 is composed of, for example, an emission microscope.

[0025] The second chamber 5 is provided with a moving unit 10 that moves the light detection unit 9. The moving unit 10 is configured to slightly move the light detection unit 9 in the x direction and the y direction. The moving unit 10 corresponds to a second moving unit.

[0026] The inspection device 1 includes a control unit 11. The control unit 11 controls the light source 6, the stage 7, the light detection unit 9, the moving unit 10, etc. The control unit 11 includes a CPU, memories such as ROM and RAM, I / O, etc., and executes predetermined processing according to a program stored in the built-in memory.

[0027] A description will be given of an object to be inspected by the inspection device 1. Here, a case will be described in which a power device such as a vertical MOS transistor having a trench electrode is inspected as the object to be inspected, and deformation of the trench electrode or the like is detected.

[0028] As shown in FIG. 2, the semiconductor device 20 to be inspected includes a substrate 21 made of Si or the like, a surface electrode 22 formed on the surface of the substrate 21, and a back electrode 23 formed on the back surface of the substrate 21.

[0029] The semiconductor device 20 also includes a trench electrode 24 formed on a surface layer of the substrate 21, and an insulating film 25 formed on the upper part of the trench electrode 24. The semiconductor device 20 is configured such that a channel is formed by applying a voltage to the trench electrode 24, and a current flows between the front electrode 22 and the back electrode 23. Note that the semiconductor device 20 may be formed in a state in which a plurality of semiconductor devices 20 are formed on a semiconductor wafer, or may be divided into chip units.

[0030] A sample used for aligning the optical axis of the light detection unit 9 with the optical axis of the light source 6 will be described. As shown in Fig. 3, the sample 30 includes a substrate 31 made of Si or the like, a surface electrode 32 formed on the surface of the substrate 31, and a back electrode 33 formed on the back surface of the substrate 31.

[0031] The substrate 31, the front electrode 32, and the back electrode 33 have the same configuration as the substrate 21, the front electrode 22, and the back electrode 23 of the semiconductor device 20. However, in the sample 30, in order to form an irradiation mark on the substrate 31 by irradiation with light from the light source 6 and to allow light emitted from the irradiation mark to be incident on the light detection unit 9, the front electrode 32 and the back electrode 33 are removed except for a part, and the front and back surfaces of the substrate 31 are exposed. For example, the inner peripheral parts of the front electrode 32 and the back electrode 33 are removed and the outer peripheral parts are left untouched, and a voltage is applied to this outer peripheral part from the stage 7.

[0032] The method of inspecting the semiconductor device 20 by the inspection device 1 will be described with reference to Figures 4 to 6. Note that in Figures 4 to 6, the stage 7 and the control unit 11 are omitted from illustration.

[0033] First, as shown in Fig. 4, the sample 30 is placed on the stage 7. Then, the control unit 11 controls the light source 6 to irradiate the sample 30 with a focused ion beam as shown by the arrow A1, thereby forming an irradiation mark on the sample 30. The diameter of the irradiation mark is set to, for example, less than 0.1 µm. In many cases, at this point, the optical axis of the light detection unit 9 shown by the arrow A2 is misaligned with the optical axis of the light source 6.

[0034] 5, the control unit 11 controls the stage 7 to apply a voltage to the sample 30, thereby causing the irradiation mark formed on the sample 30 to emit light, and the emitted light is detected by the light detection unit 9. Then, the control unit 11 controls the movement unit 10 to move the light detection unit 9 as shown by the arrow A3, thereby aligning the optical axis of the light detection unit 9 with the part that emitted light. Specifically, the control unit 11 causes the movement unit 10 to slightly move the light detection unit 9 so that the part that emitted light is detected at the center of the angle of view of the light detection unit 9, thereby reducing the deviation between the part that emitted light and the optical axis of the light detection unit 9 to about ±0.1 μm.

[0035] 6, the semiconductor device 20 is placed on the stage 7. The control unit 11 controls the stage 7 to apply a voltage to the semiconductor device 20, thereby causing a defective portion of the semiconductor device 20 to emit light. In order to detect the emitted light, a part of the back electrode 23 is removed, and a part of the back surface of the substrate 21 is exposed.

[0036] Thereafter, the control unit 11 controls the stage 7 to move the semiconductor device 20, thereby aligning the light-emitting portion with the optical axis of the photodetection unit 9. Specifically, the control unit 11 causes the stage 7 to slightly move the semiconductor device 20 so that the light-emitting portion is detected at the center of the angle of view of the photodetection unit 9, thereby reducing the deviation between the light-emitting portion and the optical axis of the photodetection unit 9 to about ±0.1 μm.

[0037] By aligning the light-emitting portion of the semiconductor device 20 with the optical axis of the light detection unit 9 in this manner, the defective portion of the semiconductor device 20 is aligned with the optical axis of the light source 6. Then, a portion of the semiconductor device 20 that corresponds to the optical axis of the light source 6 is cut out, and a cross section of the cut out portion is observed by an observation device (not shown) provided inside or outside the inspection device 1. Note that since the light detection unit 9 moves slightly due to thermal vibration, expansion, etc., the optical axis of the light detection unit 9 using the sample 30 is adjusted every time an inspection is performed.

[0038] As described above, in this embodiment, the light detection unit 9 is moved to align the optical axis of the light detection unit 9 with the irradiation mark on the sample 30, and the semiconductor device 20 is moved to align the light-emitting part with the optical axis of the light detection unit 9. This makes it possible to align the defective part with the optical axis of the light source 6 with high precision, and to detect the position of the defective part with high precision. This makes it possible to precisely cut out and observe the defective part.

[0039] In addition, since no irradiation marks are formed by the focused ion beam on the semiconductor device 20 to be inspected, it is possible to suppress changes in characteristics due to the formation of irradiation marks. Furthermore, even if the semiconductor device 20 does not have a characteristic pattern, it is possible to detect defective parts.

[0040] (Other embodiments) The present invention is not limited to the above-described embodiment, and can be modified as appropriate within the scope of the claims. In addition, in the above-described embodiment, it goes without saying that the elements constituting the embodiment are not necessarily essential, except when they are specifically stated as essential or when they are clearly considered essential in principle. In addition, in the above-described embodiment, when the numbers, values, amounts, ranges, etc. of the components of the embodiment are mentioned, they are not limited to the specific numbers, except when they are specifically stated as essential or when they are clearly limited to a specific number in principle.

[0041] A scanning transmission electron microscope may be placed in the first chamber 4, and defective areas may be observed using this electron microscope.

[0042] The light detection unit 9 may be configured with a laser microscope. In a captured image of the semiconductor device 20, defective parts such as deformed trenches scatter light and appear black, so a color pattern corresponding to the type of defect may be created in advance, and the type of defect may be estimated by comparing the captured image with this color pattern. [Explanation of symbols]

[0043] 6 light source 7 Stage 9. Light detection section 10. Moving Part 20 Semiconductor Devices 30 Samples

Claims

1. An inspection apparatus for a semiconductor device, A light source (6) for irradiating a sample (30) with light to form an irradiation mark on the sample; a voltage application unit (7) that applies a voltage to the sample to cause the irradiation mark to emit light, and applies a voltage to an inspection object (20) to cause a defective portion of the inspection object to emit light; A first moving unit (7) that moves the inspection object; A light detection unit (9) for detecting light emitted from the irradiation mark; A second moving unit (10) that moves the light detection unit, The second moving unit moves the light detection unit so as to align an optical axis of the light detection unit with the emitted irradiation mark, The first moving unit moves the inspection object so as to align the emitted defective portion with the optical axis of the light detection unit.

2. A control unit (11) for controlling the light source, the voltage application unit, the first movement unit, and the second movement unit, The control unit is forming an irradiation mark on the sample by irradiating the sample with light by controlling the light source; The voltage application unit is controlled to apply a voltage to the sample, thereby causing the irradiation mark to emit light; By controlling the second moving unit to move the light detection unit, the optical axis of the light detection unit is aligned with the light-emitting portion; controlling the voltage application unit to apply a voltage to the inspection object to cause a defective portion to emit light; 2. The semiconductor device inspection apparatus according to claim 1, wherein the first moving unit is controlled to move the inspection object, thereby aligning the light-emitting portion with the optical axis of the light detection unit.

3. An inspection apparatus for a semiconductor device, A light source (6) for irradiating a sample (30) with light to form an irradiation mark on the sample; a voltage application unit (7) that applies a voltage to the sample to cause the irradiation mark to emit light, and applies a voltage to an inspection object (20) to cause a defective portion of the inspection object to emit light; A first moving unit (7) that moves the inspection object; A light detection unit (9) for detecting light emitted from the irradiation mark; A second moving unit (10) that moves the light detection unit; a control unit (11) that controls the light source, the voltage application unit, the first movement unit, and the second movement unit, The control unit is forming an irradiation mark on the sample by irradiating the sample with light by controlling the light source; The voltage application unit is controlled to apply a voltage to the sample, thereby causing the irradiation mark to emit light; By controlling the second moving unit to move the light detection unit, the optical axis of the light detection unit is aligned with the light-emitting portion; controlling the voltage application unit to apply a voltage to the inspection object to cause a defective portion to emit light; An inspection apparatus for semiconductor devices, which controls the first moving unit to move the inspection object, thereby aligning the light-emitting portion with the optical axis of the light detection unit.

4. A method for inspecting a semiconductor device, comprising the steps of: forming an irradiation mark on a sample (30) by irradiating the sample with light; applying a voltage to the sample to cause the irradiation mark to emit light; moving the light detection unit (9) so that the optical axis of the light detection unit is aligned with the part that emits light; Applying a voltage to the inspection object (20) to cause a defective portion to emit light; and moving the inspection object to align the emitted light portion with the optical axis of the light detection unit.

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