JP4531465B2 - Blind via depth evaluation method, depth evaluation apparatus, and substrate polishing apparatus - Google Patents

Description

  The present invention relates to a blind via depth evaluation method and depth evaluation apparatus suitable for forming a through electrode on a substrate made of silicon, glass or the like, and a substrate polishing apparatus using the same.

A through electrode may be provided on a substrate for downsizing, enhancement of functions of electronic devices, optical devices, or the like, or for laminating connection between devices. As an example of a method for forming such a through electrode, a non-through hole (blind via) is formed in a substrate (semiconductor wafer), and an insulating layer is deposited on the hole wall surface of the blind via as necessary. There is a method in which a conductive material (conductive layer) is filled in the blind via, and etching or polishing is performed until the conductive layer is exposed from the back side of the substrate, and the conductive layer penetrates to the back side of the substrate (for example, patent (See paragraphs 0020 to 0023 of FIG. 1 and FIG. 2).
JP 2001-351997 A

  In order to penetrate the conductive layer, it is necessary to determine the amount of etching or polishing from the back surface of the substrate in consideration of the depth of the blind via, but there has been no good method for evaluating the depth of the blind via conventionally. It was. For example, a method of evaluating the depth of the blind via by observing the blind via using an optical microscope or the like at the stage where the blind via is formed (before formation of the conductive layer) can be considered. When the hole diameter is small and the depth is deep, there is a problem that accurate measurement is difficult. In addition, if the substrate on which the blind via is formed is transparent like glass, there is a problem that it is extremely difficult to identify the blind via in the measurement using visible light, and the depth cannot be measured.

  The present invention has been made in view of the above circumstances, and provides a depth evaluation method and a depth evaluation apparatus for evaluating the depth of a blind via filled with a conductive material, and a substrate polishing apparatus using the same. The task is to do.

In order to solve the above-mentioned problems, the present invention provides a substrate having a first marking on one surface and the other surface or one surface or the other surface, and a blind via opened in one surface of the substrate. When, an evaluation method for evaluating the depth of the blind via in the object and a second marking which is provided on the bottom of the blind via, wherein the substrate is a silicon substrate, which can transmit the substrate Reflected light generated by irradiating infrared light as detection light in the wavelength region from the other surface side toward the substrate and reflecting the detection light on the substrate side through a microscope disposed toward the substrate Is received by the light receiving means, and the first information obtained through the light receiving means when the microscope is focused on the first marking, and the microscope is focused on the second marking The second information obtained via the light receiving means is an image, and the blind via depth is calculated based on the first information and the second information. Provide a via depth evaluation method.
The present invention also provides a substrate provided with a first marking on one surface and the other surface or one surface or the other surface, a blind via opened to one surface of the substrate, and the blind via. An evaluation method for evaluating the depth of the blind via in an object provided with a second marking provided at the bottom of the substrate, wherein the substrate is a glass substrate, and detection light in a wavelength region that can be transmitted through the substrate The visible light is irradiated from the side of the other surface toward the substrate, and reflected light generated by the detection light being reflected on the substrate side through a microscope disposed toward the substrate is received by the light receiving means. First information obtained via the light receiving means when the microscope is focused on the first marking, and via the light receiving means when the microscope is focused on the second marking. The obtained second information is an image, and the blind via depth is calculated based on the first information and the second information. I will provide a.

The present invention also provides a substrate provided with a first marking on one surface and the other surface or one surface or the other surface, a blind via opened to one surface of the substrate, and the blind via. An evaluation device for evaluating the depth of the blind via in an object provided with a second marking provided on the bottom of the light source, and a light source that emits detection light in a wavelength region that can be transmitted through the substrate; A microscope disposed toward the substrate, light receiving means for receiving reflected light generated by the detection light being reflected on the substrate side, distance adjusting means for adjusting the distance between the substrate and the microscope, and the focus of the microscope First information obtained via the light receiving means when the first marking is aligned with the first marking and second information obtained via the light receiving means when the focus of the microscope is aligned with the second marking Both have a broadcast an image, based on the first information and the second information, and a computer for calculating the depth of the blind via, wherein it substrate a silicon substrate or a glass substrate, wherein When the substrate is a silicon substrate, the light source emits infrared light as the detection light, and when the substrate is a glass substrate, the light source emits visible light as the detection light. Provided is a blind via depth evaluation apparatus characterized by being ejected .
Further, the present invention provides the above-described blind via depth evaluation apparatus, and the side of the substrate opposite to the surface on which the blind via is opened, based on the blind via depth evaluated by the depth evaluation apparatus. And a polishing means for polishing from the back side which is the surface of the substrate.

According to the evaluation method and the evaluation apparatus of the present invention, when evaluating the depth of the blind via opened from one surface (front surface) of the substrate, the detection light is irradiated from the other surface (back surface) side of the substrate. The position of the bottom of the blind via can be detected by receiving the reflected light generated by reflecting the detection light on the second marking at the bottom of the blind via with the light receiving means. As the second marking, a conductive layer or an insulating layer formed in the blind via can be used.
Further, the first marking is provided on one surface and the other surface or one surface or the other surface of the substrate, and the reflected light generated by reflecting the detection light to the first marking is received by the light receiving means. It is possible to detect the position of one surface and the other surface or one surface or the other surface.
In this manner, based on the first information obtained when the microscope is focused on the first marking and the second information obtained when the microscope is focused on the second marking, It is possible to calculate and evaluate the depth of the blind via.
In order to observe the bottom of the blind via, when the detection light of the wavelength range that can be transmitted through the substrate is irradiated from the other side (back surface) of the substrate, accurate measurement is difficult as the blind via becomes finer without marking. become. However, in the present invention, since the first and second markings are made of a material having optical characteristics with respect to the detection light different from the material of the substrate, the first marking and the second marking can be easily distinguished from the substrate and can be accurately measured.
According to the polishing apparatus of the present invention, the amount of polishing from the back surface of the substrate can be determined in consideration of the depth of the blind via, and a through electrode in which the conductive layer of the blind via penetrates the substrate can be reliably obtained. be able to.

The present invention will be described below with reference to the drawings based on the best mode.
FIG. 1 is a diagram for explaining an example of the blind via depth evaluation method of the present invention, and FIG. 2 is a schematic configuration diagram showing an example of the blind via depth evaluation apparatus of the present invention.
FIG. 3 is a drawing for explaining an example of a method of manufacturing a device having a through electrode in the order of steps.

In FIG. 3A, reference numeral 21 denotes a substrate. As a material of the substrate 21, for example, silicon or glass can be used.
An element 22 is formed on one surface 21a of the substrate 21 (hereinafter, the surface indicated by reference numeral 21a may be referred to as a substrate surface). In addition, a plurality of blind vias 23 are formed in the substrate 21 in the vertical direction from the substrate surface 21a. The blind via 23 can be formed by dry etching, for example.

Next, as shown in FIG. 3B, each blind via 23 is filled with a conductive material 24 made of metal, alloy, or the like. The layer of the conductive material 24 reaches from the bottom 23b of the blind via 23 to the opening 23a. Note that an insulating layer, a barrier metal layer (not shown), or the like may be formed on the hole wall of the blind via 23 as necessary.
A metal wiring layer 25 is formed on the surface 21a of the substrate 21 by pattern wiring or the like. The conductive material 24 and the element 22 are electrically connected via the metal wiring layer 25.
Further, although not essential, the marking 26 may be formed on the back surface 21b which is the other surface of the substrate 21. The marking 26 may be formed of a conductive material in the same manner as the metal wiring layer, or may be formed by application of a paint or the like.
As for the position of the first marking provided on one surface 21a or the other surface 21b of the substrate 21, it is preferable that the positional relationship with respect to the blind via 23 is fixed. In this case, it is easy to find the marking position when the stage 15 and the like are automatically controlled.

Next, as shown in FIG. 3C, the front end of the conductive material 24 is exposed to the back surface 21 b of the substrate 21 by performing physical polishing or chemical etching from the back surface 21 b side of the substrate 21.
Thereby, as shown in FIG. 3D, a device 28 having a through electrode 27 that can take out the wiring from the element 22 to the back surface 21 b of the substrate 21 can be manufactured. Note that an insulating layer, wiring, metal bumps, or the like can be provided on the back surface 21b of the substrate 21 as necessary.

As shown in FIGS. 1A to 1C and FIG. 3B, the evaluation target 20 in the blind via depth evaluation method of this embodiment has a conductive material 24 inside the blind via 23. It is a substrate 21 filled.
1A to 1C, the object 20 is turned over so that the substrate surface 21a faces the lower side of the drawing.

  Here, a blind via depth evaluation apparatus according to this embodiment will be described with reference to FIG. The depth evaluation apparatus 10 shown in FIG. 2 includes a light source 11 that emits detection light L in a wavelength range that can be transmitted through the substrate 21, a microscope 12 that is disposed toward the substrate 21, and the detection light L on the substrate 21 side. A camera 13 as a light receiving means for receiving reflected light generated by reflection, a monitor 14 for displaying an image captured by the camera 13, a stage 15 on which a substrate 21 is placed, a stage 15 and a microscope 12 Based on the control means 16 (controller) for controlling the position, orientation, etc., information on the image picked up by the camera 13 and information on the positions of the stage 15 and the microscope 12 transmitted from the control means 16 are received. A computer 18 (computer) for calculating the depth of the blind via 23 is provided.

As the light source 11, for example, a halogen lamp or a laser light source can be used. As the light source 11, a light source that can generate detection light L in a wavelength region that can be transmitted through the substrate 21 is used. Although the wavelength range of the detection light L depends on the material of the substrate 21, it can be selected from, for example, infrared light, visible light, and ultraviolet light.
For example, when the substrate 21 is made of glass, visible light having a wavelength of about 400 nm or more and about 800 nm or less can be used as the detection light L.
Further, when the substrate 21 is made of silicon, the detection light L can be infrared light having a wavelength of about 1.1 μm or more and about 1.5 μm or less.

Although it does not specifically limit as the microscope 12, Here, the thing incorporating the objective lens 12a, the imaging lens 12b, and the half mirror 12c is used as an example.
The detection light L emitted from the light source 11 enters the half mirror 12c, changes its direction by 90 °, and is irradiated onto the substrate 21 from the back surface 21b side of the substrate 21 through the objective lens 12a. Reflected light generated by the detection light L being reflected on the substrate 21 side passes through the objective lens 12a and the half mirror 12c, is collected by the imaging lens 12b, and is captured in the camera 13 (for example, a CCD camera). An image is formed on an element (not shown), and as a result, an image signal is output by the imaging element.

The microscope 12 and the stage 15 are each provided with driving means (not shown) such as a motor. The relative movement directions of the microscope 12 and the stage 15 are preferably the Z direction (up and down direction in FIG. 2) where the microscope 12 and the stage 15 face each other, and the X direction along the surface of the stage 15 (left and right direction in FIG. 2). ) And the Y direction (in FIG. 2, the direction perpendicular to the paper surface). However, by adjusting the marking position, the present invention can be implemented even if the movement in the direction along the surface of the stage 15 is only in one direction. Furthermore, if the relative orientation (angle) between the microscope 12 and the stage 15 can be adjusted, the optical axis of the microscope 12 can be adjusted to be perpendicular to the back surface 21 b of the substrate 21. .
The control means 16 can adjust the distance between the microscope 12 and the substrate 21 by controlling the driving means for the microscope 12 and the stage 15. That is, in the present embodiment, the interval adjusting unit 17 that adjusts the interval between the microscope 12 and the substrate 21 includes the stage 15 and the control unit 16.

Next, the blind via depth evaluation method of this embodiment will be described.
First, as shown in FIG. 2, the object 20 is placed face down on the stage 15 so that the other surface 21 b of the substrate 21 faces the microscope 12. Such operation of the object 20 can also be automatically performed using a robot or the like (not shown).
When the focus of the microscope 12 is adjusted to each marking formed on the substrate 21, for example, the stage 15 is controlled to perform alignment in the X direction and the Y direction so that the marking position is on the optical axis of the microscope 12. .

  As shown in FIG. 1A, the microscope 12 is focused on one surface 21 a of the substrate 21. The relative position of the microscope 12 and the stage 15 at that time (for example, the distance A between the microscope 12 and the stage 15) is transmitted from the control means 16 to the computer 18 as the first information. When focusing on one surface 21a of the substrate 21, for example, the metal wiring layer 25 formed on the substrate surface 21a may be used as a marking (first marking) and focused on this. The metal wiring layer 25 to be used for marking is not limited to the wiring connecting the element 22 and the conductive material 24 in the blind via 23, but other parts of other metal wiring layers, dummy wiring, or the like may be used. it can. In addition, as the first marking provided on one or the other surface 21a, 21b of the substrate 21, as long as it is opaque to the detection light L (that sufficiently reflects the detection light), even if it is not a conductive layer, It is also possible to use a printed layer (if any) on the substrate surface 21a.

As shown in FIG. 1B, the microscope 12 is focused on the bottom 23b of the blind via 23, and the relative position between the microscope 12 and the stage 15 (for example, the distance B between the microscope 12 and the stage 15) is set. The second information is transmitted from the control means 16 to the computer 18. When focusing on the bottom 23b of the blind via 23, as the second marking, for example, an insulating layer formed on the bottom of the conductive material 24 filled in the blind via 23 or the hole wall of the blind via 23, A barrier metal layer (not shown) or the like may be used to focus on the position of the second marking.
Further, a layer made of a material suitable as the second marking may be formed only on the bottom 23b of the blind via 23. In this case, as shown in FIG. 3C, when penetrating the blind via 23 in the polishing process, the second marking portion can be removed.

  In the computer 18, the relative position (first information) between the microscope 12 and the stage 15 in FIG. 1A and the relative position (second information) between the microscope 12 and the stage 15 in FIG. Based on this, the blind via depth is calculated. If the refractive index of the substrate 21 is equal to the refractive index of the external atmosphere (air, etc.) (referred to as the refractive index at the wavelength of the detection light), the difference in the distance between the microscope 12 and the stage 15 in the two states ( That is, B−A) corresponds to the depth d of the blind via 23, but actually it is necessary to correct based on the refractive index n of the material of the substrate 21.

When the marking 26 is also provided on the other surface 21b of the substrate 21, the microscope 12 is focused on the marking 26 on the other surface 21b of the substrate 21, and the microscope 12 and the stage 15 at that time are relative to each other. The target position (for example, the distance C between the microscope 12 and the stage 15) can be transmitted from the control means 16 to the computer 18.
At this time, if the thickness of the substrate 21 is t and the depth of the blind via 23 is d, the relationship shown in Expression (1) is established, so that the depth d of the blind via 23 can also be calculated.

(BA) / (CA) = d / t (Formula 1)

The polishing apparatus of the present invention polishes the back surface 21b of the substrate 21 as shown in FIG. 3C in order to expose the tip of the conductive material 24 inside the blind via 23 to the back surface 21b of the substrate 21 as described above. Sometimes, the polishing amount of the substrate 21 is determined in consideration of the thickness t of the substrate 21 and the depth d of the blind via 23. In order for the conductive material 24 in the blind via 23 to penetrate, it is preferable to polish slightly more than the difference (t−d) obtained by subtracting the depth d of the blind via 23 from the thickness t of the substrate 21.
When the substrate 21 has a plurality of blind vias 23, in order for the conductive material 24 in all the blind vias 23 to penetrate, the depth d of the plurality of blind vias 23 is measured, and the depth of the shallowest blind via 23 is measured. It is preferable to determine the polishing amount of the substrate 21 based on the thickness. Thereby, even when there is variation in the depth of the blind via 23, the operation of manufacturing a device through which the conductive material 24 in all the blind vias 23 penetrates is facilitated.

As described above, according to the depth evaluation method of this embodiment, the position of the bottom of the conductive material filled in the blind via and the one surface and the other surface of the substrate or one surface or the other surface. The depth of the blind via can be numerically evaluated based on the position of Thereby, the polishing amount for penetrating the blind via can be determined more reliably.
Since the position of the bottom of the conductive material filled in the blind via is measured, it is easier to focus the optical microscope than in observing the bottom of the blind via filled with nothing.
Further, since the bottom of the blind via is observed from the back side of the substrate, highly accurate measurement is possible even with a blind via having a fine diameter and a deep depth.
The depth evaluation method of this embodiment is automated by providing a robot or the like for placing the object on the stage in an appropriate direction and setting the drive of the stage, microscope, etc. to be automatically controlled. In this case, the labor required for the evaluation and polishing operations can be greatly reduced.

<Example 1>
A plurality of blind vias having a depth of about 300 μm and a diameter of about 80 μm were formed from one surface of a glass substrate (diameter: 4 inches (about 10 cm), thickness: about 525 μm) by dry etching. A He—Ne laser with a wavelength of 633 nm was used as the light source, and the depth of the blind via was evaluated using the evaluation apparatus shown in FIG.
Thus, after evaluating the depth of the blind via by the non-destructive evaluation method of the present invention, the substrate was cut to expose the blind via along the depth direction, and the depth of the blind via was measured. . When the obtained actual measurement value was compared with the evaluation value according to the present invention, it was found that the depth of the blind via can be evaluated with practical accuracy by the present invention.

<Example 2>
A plurality of blind vias having a depth of about 300 μm and a diameter of about 80 μm were formed by dry etching from one surface of a substrate made of silicon (diameter: 4 inches (about 10 cm), thickness: about 525 μm). A halogen lamp having a wavelength of 1.3 μm was used as the light source, and the depth of the blind via was evaluated using the evaluation apparatus shown in FIG.
Thus, after evaluating the depth of the blind via by the non-destructive evaluation method of the present invention, the substrate was cut to expose the blind via along the depth direction, and the depth of the blind via was measured. . When the obtained actual measurement value was compared with the evaluation value according to the present invention, it was found that the depth of the blind via can be evaluated with practical accuracy by the present invention.

  The present invention can be used for manufacturing a semiconductor device or an electronic device having a through electrode.

It is drawing explaining an example of the depth evaluation method of the blind via of this invention. It is a schematic block diagram which shows an example of the depth evaluation apparatus of the blind via of this invention. It is process drawing which shows an example of the manufacturing method of the board | substrate with a penetration electrode using the grinding | polishing method of the board | substrate of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Blind-via depth evaluation apparatus, 11 ... Light source, 12 ... Microscope, 13 ... Light-receiving means, 17 ... Space | interval adjustment means, 18 ... Computer, 20 ... Object, 21 ... Substrate, 21a ... One side of substrate ( Substrate surface), 21b ... the other side of the substrate (back side), 23 ... blind via, 23b ... bottom of the blind via, 24 ... conductive material (second marking), 25 ... metal wiring layer (first marking) , 26 ... marking, d ... depth of blind via, L ... detection light.

Claims (4)

A board provided with a first marking on one side and the other side or one side or the other side, a blind via opened on one side of the substrate, and provided at the bottom of the blind via An evaluation method for evaluating the depth of the blind via in an object comprising a second marking,
Wherein the substrate is a silicon substrate, the infrared light is irradiated toward the substrate from the side of the other surface of the substrate as the detection light transmissible wavelength range,
The reflected light generated by the detection light being reflected on the substrate side through the microscope disposed toward the substrate is received by the light receiving means,
First information obtained via the light receiving means when the microscope is focused on the first marking, and obtained via the light receiving means when the microscope is focused on the second marking A blind via depth evaluation method, wherein the second information is an image, and the depth of the blind via is calculated based on the first information and the second information. A board provided with a first marking on one side and the other side or one side or the other side, a blind via opened on one side of the substrate, and provided at the bottom of the blind via An evaluation method for evaluating the depth of the blind via in an object comprising a second marking,
Wherein the substrate is a glass substrate, the visible light is irradiated toward the substrate from the side of the other surface of the substrate as the detection light transmissible wavelength range,
The reflected light generated by the detection light being reflected on the substrate side through the microscope disposed toward the substrate is received by the light receiving means,
First information obtained via the light receiving means when the microscope is focused on the first marking, and obtained via the light receiving means when the microscope is focused on the second marking A blind via depth evaluation method, wherein the second information is an image, and the depth of the blind via is calculated based on the first information and the second information. A board provided with a first marking on one side and the other side or one side or the other side, a blind via opened on one side of the substrate, and provided at the bottom of the blind via An evaluation device for evaluating the depth of the blind via in an object provided with a second marking,
A light source that emits detection light in a wavelength range that can be transmitted through the substrate;
A microscope disposed toward the substrate;
A light receiving means for receiving reflected light generated by the detection light being reflected on the substrate side;
An interval adjusting means for adjusting an interval between the substrate and the microscope;
First information obtained via the light receiving means when the microscope is focused on the first marking, and obtained via the light receiving means when the microscope is focused on the second marking The second information is an image, and a computer for calculating the depth of the blind via based on the first information and the second information;
Equipped with a,
The substrate is a silicon substrate or a glass substrate;
When the substrate is a silicon substrate, the light source emits infrared light as the detection light,
When the substrate is a glass substrate, the light source emits visible light as the detection light . The blind via depth evaluation apparatus according to claim 3 ,
Polishing means for polishing the substrate from the back surface side opposite to the surface on which the blind via is opened based on the depth of the blind via evaluated by the depth evaluation device. A substrate polishing apparatus.

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