JP2007324457A - Support jig used in failure analysis of semiconductor device and failure analysis method using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a support jig capable of obtaining a sufficient pattern resolution, resolution ability, and detection sensitivity for a miniaturized semiconductor device, in a backside analysis of the semiconductor device, and a failure analysis method. <P>SOLUTION: There is provided a support jig of a semiconductor device used in failure analysis for observing luminescence emitted through the observed part of the backside of the semiconductor device, in a state of applying a probe onto the surface of the semiconductor device. The support jig includes a contact coming in contact with a region excluding the observed part of the backside of the semiconductor device and a support, with one end side fixed to the contact and the other end side fixed to a part other than the semiconductor device. The contact is moved relatively to a wafer, so that the center of the contact approximately coincides with the center of the probe in analysis. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a support jig used for failure analysis from the back surface of a semiconductor device, and a failure analysis method using the support jig.

  In failure analysis of semiconductor devices, emission analysis (also called emission analysis) that performs failure analysis by detecting faint light generated from the current leak location, and failure location is identified by detecting heat generation from the current leak location Heat generation analysis, OBIC (Optical Beam Induced Current) analysis and OBIRCH (Optical Beam Induced Resistance CHange) analysis to identify the failure location by converting the change in electromotive current or power supply current generated by laser beam irradiation into an image, etc. This is a general analysis method in that it is easy to identify the failure location. In these analysis methods, failure analysis from the back surface of the semiconductor substrate (hereinafter simply referred to as “back surface analysis”) is indispensable due to the recent increase in the number of semiconductor devices and the flip chip packaging of packages.

  FIG. 6 is a cross-sectional view illustrating an example in which the back surface analysis of the semiconductor device is performed with the wafer on which the semiconductor device is built. This figure schematically shows a case where the above-described light emission analysis is performed in combination with a tester.

Further, in Patent Document 1, a high resolution is obtained by using a solid immersion lens (Solid Immersion Lens, hereinafter referred to as “SIL”) plate 102 made of Si, and a stable analysis is performed on the stage 101. A technique that can mount the target semiconductor device 2 and can move the analysis visual field is disclosed. An example of the analysis apparatus in Patent Document 1 is shown in FIG. 7 as a cross-sectional view.
JP 2004-327773 A

  By the way, in microscopic observation, the resolution d in observation is expressed by d = λ / (2 × n × sin θ), and is determined by the wavelength λ of the light used and the refractive index n of the objective lens (note that θ is the optical axis) The half angle of the light collection angle with respect to. Here, since the light used is often selected depending on the measurement conditions, an objective lens with a high refractive index n (ie, a large numerical aperture NA) is eventually selected to reduce the resolution d. It will respond by doing. However, since an objective lens made of a material having a high refractive index n usually has a short focal length f, the distance between the object to be observed and the objective lens (also referred to as an operating distance or WD) cannot be made too long.

  In Conventional Example 1 shown in FIG. 6, the probe 31 of the probe card 3 is applied to the semiconductor device of the wafer 2, a test pattern signal is applied, and the failure portion is caused to emit light. This light is captured from the back surface of the wafer 2 by the objective lens 4 of the failure analysis apparatus, and failure analysis is performed. In this case, in order to use near infrared light or infrared light that passes through a semiconductor substrate (in most cases, Si) as light to be captured, the thickness of the wafer 2 needs to be reduced from about 100 μm to about 400 μm. . Therefore, when the wafer 2 is fixed only by the wafer chuck 5 and the wafer clamp 6, the strength of the wafer 2 cannot withstand the pressure of the probe 31 and the wafer 2 is damaged. Therefore, in the back surface analysis, the entire wafer 2 is supported by the stage 101 made of quartz glass. However, there is a problem that the working distance must be increased due to the thickness of the stage 101, and an objective lens having a high refractive index n that can obtain a sufficient resolution d cannot be selected. In addition, there is a problem that the light emitted to the quartz glass is absorbed or reflected and the measurement sensitivity is lowered.

  On the other hand, in the case of Patent Document 1, it is necessary to interpose the stage 101 between the SIL plate 102 and the objective lens 4, and there is a problem that the resolution is lowered by the thickness of the stage 101 and the SIL plate 102.

  The present invention has been made to solve the above-described problems, and in a back surface analysis of a semiconductor device, a support jig capable of obtaining sufficient pattern resolution, resolution and detection sensitivity for a miniaturized semiconductor device, It is another object of the present invention to provide a failure analysis method.

(1) A support jig for a semiconductor device according to the present invention is used in failure analysis in which light emitted through an observed portion on the back surface of a semiconductor device is observed with a probe applied to the surface of the semiconductor device. A support jig for a semiconductor device, which is in contact with a region excluding the observed portion on the back surface side of the semiconductor device, one end side being fixed to the contact portion, and the other end side being a place other than the semiconductor device And a fixed support portion, wherein the contact portion moves relative to the wafer so that the center of the contact portion substantially coincides with the center of the probe at the time of analysis.
(2) In the above (1), the lens is a solid immersion lens.
(3) In the above (1) or (2), there is provided a positioning means capable of moving the contact portion in the vertical direction and the horizontal direction.
(4) A failure analysis method for a semiconductor device according to the present invention is a failure analysis method for a semiconductor device in which light emitted through an observed portion on the back surface of the semiconductor device is observed with a probe applied to the surface of the semiconductor device. , Relatively moving the contact portion and the wafer so that the center of the contact portion of the support jig of the semiconductor device used for the observation substantially coincides with the center of the probe at the time of analysis, The contact portion is brought into contact with the back surface of the semiconductor device, and a probe is applied to the semiconductor device.

  In the present invention, in the backside analysis of the semiconductor device, the semiconductor device does not have to be supported from the backside by the stage, so that it is possible to prevent a reduction in resolution and measurement sensitivity due to the thickness of the stage.

  An embodiment of the failure analysis method according to the present invention will be described with an example. FIG. 1 is a cross-sectional view from the side schematically showing an example of the embodiment. FIG. 2 is an enlarged perspective view of the central portion of FIG. In both figures, the same components as those in FIGS. 6 and 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In FIG. 1, the semiconductor device 21 built in the wafer 2 is analyzed for failure from the back surface of the wafer 21 by a failure analysis device (not shown) provided with the objective lens 4.

  A wafer chuck 5 having a vacuum suction function is placed with the back surface of the wafer 2 facing the failure analyzer (upper side in this figure), and the wafer clamp 6 fixes only the outer peripheral edge of the wafer 2. Then, the wafer chuck 5 fixes the wafer 2 installed by vacuum suction, and prevents the displacement of the analysis location after the probe 31 contacts. The wafer chuck 5 can move the wafer 2 parallel to the wafer surface by a chuck driving device (not shown). Further, the wafer chuck 5 can move the wafer 2 along a direction perpendicular to the wafer surface.

  A solid immersion lens unit 7 for increasing the resolution d is provided at the tip of the objective lens 4. A solid immersion lens 71 is attached to the tip of the solid immersion lens unit 7 and is used in close contact with an observation object (wafer 2 in the present embodiment).

  A probe card 3 is disposed below the wafer 2. The probe card 3 is further electrically connected to the tester head 32. The probe 31 of the probe card 3 is applied to the electrode pad of the semiconductor device 21 on the wafer 2, and a test pattern signal necessary for failure analysis is applied to the semiconductor device 21. The test pattern signal is generated by a tester (not shown) and supplied to the probe card 3 via the tester head 32.

  Further, the support jig 1 according to the present invention is in contact with the periphery of the solid immersion lens 71 and the back surface of the wafer 2 which is substantially the back side of the semiconductor device 21 to be analyzed.

  The support jig 1 according to the present invention includes a contact portion 11 and a support portion 12 having one end fixed to the contact portion 11. FIG. 3 is a top view schematically showing the support jig 1. The contact portion 11 is in contact with the position on the back surface side facing the location where the probe 31 is in contact by vacuum suction. Because of this role, the contact portion 11 is accurately kept parallel to the wafer 2. On the other hand, one end of the support portion 12 is fixed to the contact portion 11. Furthermore, in this case, the other end of the support portion 12 is fixed to the positioning means 13. The positioning means 13 can move the contact portion 11 in the vertical direction and the horizontal direction, and can also be fixed at an arbitrary position after the movement. The positioning means 13 is fixed to a manipulator fixing base (not shown) of the failure analysis apparatus. That is, the support portion 12 is fixed to the contact portion 11 and is also fixed to the failure analysis device.

  With this structure, the support jig 1 can support the force applied to the surface of the wafer 2 by the probe 31 from the back surface of the wafer 2. That is, the contact portion 11 can transmit the force applied to the surface of the wafer 2 from the probe 31 from the back surface of the wafer 2 to the support portion 12, while the support portion 12 is transmitted from the contact portion 11. Thus, the force applied to the wafer 2 can be supported. The support jig 1 supports the wafer 2 from the back surface independently of the objective lens 4 and the solid immersion lens unit 7.

  The contact portion 11 is formed by deforming an elongated tubular member into an arbitrary shape and closing both ends, and the shape depends on the shape of the semiconductor device 21 to be analyzed. A desirable shape of the contact portion 11 is a similar shape of the semiconductor device 21, and most desirably, the same size as the semiconductor device 21. An example of the shape of the contact portion 11 is shown in FIG. 4A shows a case where the shape of the analysis target device is a square, and FIG. 4B shows a case where the shape of the analysis target device is a rectangle. In FIG. 4A and FIG. 2B, the shape of the contact portion 11 is similar to that of the semiconductor device 21, and the contact portion 11 is disposed so as to surround the semiconductor device 21. Further, the analysis is performed by the objective lens 4 and the solid immersion lens 71 of the failure analysis device through the vacant center portion. Or it is good also as circular shape like FIG. 4 (3). In this case, it can be used universally regardless of the shape of the semiconductor device 21 to be analyzed.

  Furthermore, it is most desirable that the position where the contact portion 11 is brought into contact with the back surface of the wafer 2 is directly above the location where the probe 31 contacts. However, since the position may interfere with the analysis with the eyepiece 4 or the solid immersion lens 71, it is desirable that the contact portion 11 is brought into contact slightly outside the location where the probe 31 hits. That is, even if it is not directly above (or directly below) the location where the probe 31 hits, even if the contact position is changed outside the location where the probe 31 hits within the range where the wafer 2 is not damaged, it is still within the scope of the present invention. Play. By selecting an appropriate shape and contact position of the contact portion 11 according to the shape and dimensions of various semiconductor devices, sufficient strength against the pressure of the probe 31 can be obtained.

  At least the contact portion 11 has a hollow inside, and a suction hole is formed in a surface that contacts the wafer 2. The contact portion 11 is arranged on the back surface of the wafer 2 so that the suction holes are closed by the wafer 2 when contacting the wafer 2. Then, by exhausting the air in the contact portion 11 to the outside of the contact portion 11, the contact portion 11 vacuum-sucks the back surface of the portion of the wafer 2 where the probe 31 hits.

  The material of the support jig 1, particularly the portion other than the positioning means 13, may be anything as long as it has sufficient strength to receive the pressure from the probe 31 without contaminating the wafer 2. Specific examples include stainless steel, aluminum alloy, ceramics, and the like.

  As long as the contact portion 11 can be moved in the horizontal direction and the vertical direction, the positioning means 13 may have any structure. It is more preferable if it can be fixed at any position, and even more preferable if it can be finely moved in the vertical direction. Specifically, a three-axis manipulator with a vacuum chuck, which is often used in failure analysis apparatuses, is most desirable. The manual three-axis manipulator shown in FIG. 3 can be moved and fixed by the three knobs 13a, 13b, and 13c, and can be fixed to the manipulator base of the failure analysis apparatus by vacuum suction or the like. Moreover, if the support part 12 is arm shape, it will be easily attached to the said manipulator, and replacement | exchange of the contact part 11 currently fixed to the support part 12 will also become easy. The three-axis manipulator may be manually operated or electrically operated.

Next, the measurement procedure of the embodiment of the failure analysis method described above will be described. The procedure is in the following order (1) to (8).
(1) First, the positioning means 13 of the support jig 1 positions the contact portion 11 in the horizontal direction and further fixes it. At this time, the contact portion 11 is arranged so that the center of the contact portion 11 and the center of the probe 31 substantially coincide with each other when viewed from the upper surface of the contact portion 11 (see FIG. 5A). If the center of the probe 31 and the center of the contact portion 11 are fixed while being largely deviated (see FIG. 5B), the pressure from the probe 31 on the wafer 2 becomes non-uniform and the wafer 2 may be damaged. Becomes higher.

That is, “substantially” in the above “substantially match” indicates a range in which the pressure from the probe 31 on the wafer 2 does not become non-uniform, and as a result, the wafer 2 is not damaged.
(2) Next, the back surface of the wafer 2 is set on the wafer chuck 5 with the failure analysis device side (upper side in FIG. 1), and the wafer 2 is fixed by vacuuming with the wafer clamp 6.
(3) Then, the semiconductor device 21 to be analyzed (hereinafter referred to as a sample) is positioned so as to face the probe 31.
(4) Then, the contact portion 11 is brought closer to the wafer 2 little by little by the positioning means 13 so as to be brought into contact with the back surface of the wafer accurately so that no excessive pressure is applied. Then, the contact portion 11 is vacuum-sucked on the back surface of the wafer.
(5) After (4) above, the probe 31 of the probe card 3 is brought into contact with the electrode pad of the sample.
(6) When the solid immersion lens 71 is used, the solid immersion lens 71 is brought into close contact with the analysis location. At this time, in order to improve the adhesion of the solid immersion lens 71, an adhesion liquid may be applied to a position where the wafer 2 is to be adhered.
(7) After contact with the solid immersion lens 71, a test pattern is applied to the sample via the probe card 3 and the failure analysis is performed in the same manner as in the procedure of the conventional failure analysis method.
(8) When the sample is to be changed to another semiconductor device 21 in the same wafer 2, the probe card 3 is lowered and removed from the sample, and then the vacuum suction of the contact portion 11 of the support jig 1 is stopped. The contact portion 11 is released from the close contact with the back surface of the wafer 2 and released. Further, the wafer 2 is moved in the horizontal direction by the wafer chuck 5 to move the next sample onto the probe card 3.

  The above steps (1) to (8) may be repeated until there is no semiconductor device 21 requiring failure analysis in the wafer 2.

  According to the present invention, since the wafer 2 does not have to be supported by the conventional quartz glass stage 101, a single semiconductor device (for example, a state of chips separated from the wafer) or a plurality of semiconductor devices Regardless of the situation in which the wafer is gathered (for example, the state of the wafer before being separated), it is possible to prevent the resolution and measurement sensitivity from being lowered due to the thickness of the stage. Further, the movement within the same wafer 2 is easy, and the efficiency of analysis can be improved.

  When the solid immersion lens 71 is used as in the present embodiment, the back surface of the semiconductor device 21 of the wafer 2 is supported by the support jig 1 even if the solid immersion lens 71 is brought into close contact with the back surface of the analysis location. Therefore, the solid immersion lens 71 can be mounted without damaging the wafer 2. For this reason, the solid immersion lens 71 can be used in the light emission analysis, heat generation analysis, OBIC or OBIRCH analysis from the back surface of the wafer 2 which was not possible conventionally. This enables backside analysis with high resolution, high resolution, and high sensitivity, and enables device analysis using recent miniaturization processes and multilayer wiring processes.

  In the present embodiment, the signal application to the semiconductor device 21 has been described with the probe card 3 and the probe 31, but may be performed with a manipulator and a probe attached to the manipulator.

  In the present embodiment, the contact portion 11 is brought into contact with the wafer 2 by vacuum suction, but the present invention is not limited to this. What is necessary is just to select suitably from the contact means generally used in manufacture of a semiconductor device. Specifically, an electrostatic chuck can be applied. Or you may make it contact the wafer 2 by adjusting the position of the perpendicular direction of the contact part 11, without providing these contact means. For example, even if the contact portion 11 is fixed to a height at which the contact portion 11 can be pressed against the wafer 2 using the positioning means 13, the effect of the present invention can be sufficiently achieved.

  In the present embodiment, the objective lens 4 and the solid immersion lens 71 are described in combination. However, the present invention is not limited to this. Even if an immersion lens typified by an oil lens is used or observation is performed using only the objective lens 4, the effects of the present invention can be obtained. In accordance with the purpose of analysis and the required observation magnification or required resolution d, an optical system generally used in the manufacture of semiconductor devices may be selected as appropriate.

It is sectional drawing which showed typically the failure analysis method which concerns on this invention. It is the perspective view which expanded the center part of FIG. It is the top view which showed typically the support jig which concerns on this invention. It is the top view which showed typically the shape of the contact part of the support jig which concerns on this invention. It is the top view which showed typically the positioning method of the support jig which concerns on this invention. It is sectional drawing which showed typically the example which is analyzing the back surface of the wafer in which the semiconductor device was built (conventional example 1). It is sectional drawing which showed the example of the technique disclosed by patent document 1 typically (conventional example 2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support jig 11 Contact part 12 Support part 13 Positioning means 2 Wafer 21 Semiconductor device 3 Probe card 31 Probe 32 Tester head 4 Objective lens 5 Wafer chuck 6 Wafer clamp 7 Solid immersion lens unit 71 Solid immersion lens (SIL)
101 Quartz glass stage 102 SIL plate 103 Chuck

Claims (4)

A semiconductor device support jig used in failure analysis for observing light emission emitted through a portion to be observed on the back surface of a semiconductor device with a probe applied to the surface of the semiconductor device,
A contact portion in contact with a region excluding the observed portion on the back side of the semiconductor device;
One end side is fixed to the contact portion, and the other end side includes a support portion fixed to a place other than the semiconductor device,
A support jig for a semiconductor device, wherein the contact portion moves relative to the wafer so that the center of the contact portion substantially coincides with the center of the probe at the time of analysis.   The semiconductor device support jig according to claim 1, wherein the lens is a solid immersion lens.   The support jig according to claim 1, further comprising a positioning unit capable of moving the contact portion in a vertical direction and a horizontal direction. In a failure analysis method for a semiconductor device that observes light emitted through an observed portion on the back surface of the semiconductor device with a probe applied to the surface of the semiconductor device,
Relatively moving the contact portion and the wafer so that the center of the contact portion of the support jig of the semiconductor device used for the observation substantially coincides with the center of the probe at the time of analysis;
Next, a failure analysis method for a semiconductor device, wherein the contact portion is brought into contact with the back surface of the semiconductor device, and a probe is applied to the semiconductor device.

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