SEMICONDUCTOR DEVICE MANUFACTURING METHOD

To provide a manufacturing method of a semiconductor device including a semiconductor substrate, the manufacturing method of the semiconductor device including a sticking for sticking a protection tape to a first surface of the semiconductor substrate, a first grinding for supporting the protection tape and grinding a second surface of the semiconductor substrate that is a surface on the opposite side of the first surface, a protection tape cutting for supporting the second surface of the semiconductor substrate and flattening the protection tape, and a second grinding for supporting the protection tape and grinding the second surface of the semiconductor substrate. In the second grinding, in order to leave a convex part in an outer circumference of the semiconductor substrate, an inside of the convex part may be ground.

The contents of the following Japanese patent application(s) are incorporated herein by reference:NO. 2021-044168 filed in JP on Mar. 17, 2021NO. PCT/JP2022/003409 filed in WO on Jan. 28, 2022

TECHNICAL FIELD

The present invention relates to a manufacturing method of a semiconductor device.

BACKGROUND

Conventionally, in grinding methods of a semiconductor substrate, a technique of “cutting the entire front surface of a base film of a protection tape adhered to a front surface of a wafer (substrate) with a cutting tool in a range that does not reach an adhesive layer”, and then “retaining the front surface of the wafer to which the protection tape is adhered, with a chuck table of a grinding device via the protection tape” has been known (for example, refer to Patent Document 1). In addition, in processing methods of a semiconductor substrate, a technique of “forming a concave part in a region corresponding to a device region among a back surface of a wafer (substrate), and forming a ring-shaped reinforced part including an outer circumferential excessive region on the outer circumferential side of the concave part” has been known (for example, refer to Patent Document 2).

Patent Document 2: Japanese Patent Application Publication No. 2007-19461

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all combinations of features described in the embodiments are essential to the solution of the invention. It should be noted that, in the present specification and drawings, elements having substantially the same functions and configurations are denoted with the same reference signs, and the overlapping descriptions thereof are omitted. In addition, the elements that are not directly relevant to the present invention are not shown. In one drawing, elements having the same function and configuration are representatively denoted by a reference sign, and the reference signs for the others may be omitted.

As used herein, one side in a direction parallel to a depth direction of a semiconductor substrate is referred to as “upper” and the other side is referred to as “lower”. One surface of two principal surfaces of a substrate, a layer or other member is referred to as an upper surface, and the other surface is referred to as a lower surface. The ‘upper’ and ‘lower’ directions are not limited to a gravity direction or a direction at a time of mounting a semiconductor module.

In the present specification, technical matters may be described using orthogonal coordinate axes of an X axis, a Y axis, and a Z axis. The orthogonal coordinate axes merely specify relative positions of components, and do not limit a specific direction. For example, the Z axis is not limited to indicate the height direction with respect to the ground. It should be noted that a +Z axis direction and a −Z axis direction are directions opposite to each other. When the Z axis direction is described without describing the signs, it means that the direction is parallel to the +Z axis and the −Z axis. As used herein, the orthogonal axes parallel to an upper surface and a lower surface of the semiconductor substrate are defined as the X axis and the Y axis. In addition, the axis perpendicular to the upper surface and the lower surface of the semiconductor substrate is defined as the Z axis. As used herein, the direction of the Z axis may be referred to as the depth direction. In addition, as used herein, a direction parallel to the upper surface and the lower surface of the semiconductor substrate, including the X axis and the Y axis, may be referred to as a horizontal direction.

As used herein, a case where a term such as “same” or “equal” is mentioned may include a case where an error due to a variation in manufacturing or the like is included. The error is, for example, within 10%.

FIG.1illustrates an example of a manufacturing method of a semiconductor device100. The manufacturing method of the semiconductor device100includes a table processing S104, a sticking S101, a first grinding S102, a protection tape cutting S103, and a second grinding S105. In the table processing S104, a table used in the second grinding S105is processed. Hereinafter, each step will be described inFIG.2toFIG.7B. It should be noted that details of the table processing5104will be described later inFIG.6.

It should be noted that, as an example, the semiconductor device100functions as a power conversion device such as an inverter. The semiconductor device100may include a diode such as an insulated gate bipolar transistor (IGBT), FWD (Free Wheel Diode) and RC (Reverse Conducting)—IGBT provided by combining the two, and a MOS transistor or the like. Also, the semiconductor device100, as an example, functions as a pressure sensor. The semiconductor device100may not be limited to these examples.

FIG.2illustrates an example of the sticking S101. The semiconductor device100includes a semiconductor substrate10. In the present example, the semiconductor substrate10is a substantially circular wafer, as seen from above. In the present specification, processes except for a process for grinding the semiconductor substrate10are omitted. The manufacturing method of the semiconductor device100may include: a process for implanting an impurity to a predetermined region of the semiconductor substrate10; a process for annealing the semiconductor substrate10; and a process for forming an insulating film, electrode or wiring or the like on a front surface of the semiconductor substrate10. By those processes, a semiconductor device such as a transistor is formed on the semiconductor substrate10. The semiconductor substrate10is a substrate formed of a semiconductor material. Although the semiconductor substrate10is a silicon substrate by way of example, the material of the semiconductor substrate10is not limited to silicon. As a diameter D1of the semiconductor substrate10, 200±5 mm or 300±5 mm is frequently used as an example. However, it is not limited to this value.

In the sticking S101, a protection tape20is stuck to a first surface11of the semiconductor substrate10. The first surface11of the semiconductor substrate10may be a surface on which a gate structure such as an IGBT or a MOS transistor is formed. The gate structure is, for example, a structure including at least one of a gate electrode, a gate insulating film, a source region, an emitter region, and a channel region. In the sticking S101, the gate structure may be already formed, or may yet to be formed, on the first surface11. The first surface11of the semiconductor substrate10may be a so-called device surface. By sticking the protection tape20to the first surface11of the semiconductor substrate10, the first surface11of the semiconductor substrate10can be protected.

The protection tape20is a tape for protecting the first surface11of the semiconductor substrate10. Specifically, by sticking the protection tape20, when grinding a second surface12of the semiconductor substrate10in the first grinding S102and the second grinding S105, the first surface11of the semiconductor substrate10can be prevented from directly contacting a table of a grinding device. The protection tape20may be a tape having adhesion. For example, a UV tape or a pressure sensitive tape is generally used for the protection tape20. However, other than these, an organic coating film as represented by a resist, an attachment sheet by an electrostatic force, a support disc to which an adhesive agent is applied, or the like also can be used. The second surface12of the semiconductor substrate10is a surface on the opposite side of the first surface11of the semiconductor substrate10.

After sticking the protection tape20, the protection tape20is preferably cut to flatten the protection tape20. In this case, the second surface12of the semiconductor substrate10is placed on the table to cut the protection tape20. However, as shown inFIG.2, a foreign substance30may adhere to the second surface12of the semiconductor substrate10. The foreign substance30is a foreign substance that is adhered in the manufacturing process of the semiconductor device100. The foreign substance30may be a particle or the like, or may be an organic matter such as a resist or a residue of an oxide film. If the foreign substance30is adhered to the second surface12of the semiconductor substrate10, when flattening the protection tape20in the protection tape cutting S103, a problem that the protection tape20does not become flat will be caused. This problem will be described later inFIG.13toFIG.16C.

FIG.3AandFIG.3Billustrate examples of the first grinding S102.FIG.3Aillustrates the semiconductor device100before grinding, in the first grinding S102.FIG.3Billustrates the semiconductor device100after grinding, in the first grinding S102.

In the first grinding S102, the second surface12of the semiconductor substrate10is ground. As shown inFIG.3A, in the first grinding S102, the protection tape20is supported by a table120. In addition, in the first grinding S102, the first surface11of the semiconductor substrate10is supported by the table120. In the present example, the first surface11of the semiconductor substrate10is supported by the table120via the protection tape20. The table120may be a chuck table. The table120has an upper surface121and a lower surface123. In addition, in the first grinding S102, the second surface12of the semiconductor substrate10is ground by a whetstone122. The first grinding S102is, for example, performed using a grinding device such as a back grinder (BG). By grinding the second surface12of the semiconductor substrate10, the foreign substance30can be removed. In the first grinding S102, the second surface12may be ground by inclining the whetstone122forward. Inclining the whetstone122forward refers to inclination of the whetstone122with respect to a circumferential direction of the semiconductor substrate10. In the example ofFIG.3A, the lower surface of the whetstone122is arranged to have an inclination (forward inclination angle) with respect to the Y axis direction. The forward inclination angle will be described later inFIG.17. In addition, inFIG.3A, an average thickness of the semiconductor substrate10is denoted by T1. As used herein, the thickness is a difference between a height of the upper surface and a height of the lower surface in the Z axis direction. InFIG.3A, the average thickness T1of the semiconductor substrate10is a difference between a height of the second surface12and a height of the first surface11. As used herein, the height is a height from a certain reference. In each figure, the reference may be a portion that is provided on the lowest side in the Z axis direction among each component. InFIG.3A, the reference is, for example, the lower surface123of the table120. It should be noted that, although the whetstone122is described smaller than the semiconductor substrate10inFIG.3A, the diameter of the whetstone122may be larger than the diameter of the semiconductor substrate10.

As shown inFIG.3B, after the first grinding S102, the semiconductor substrate10is processed to have a shape in which a center part14becomes convex. It should be noted that, in each figure, concavities and convexities of the semiconductor substrate10and the like are exaggeratedly shown. The center part14is a portion including the center of the semiconductor substrate10in the XY plane. In addition, the semiconductor substrate10may have a valley part18between the center part14and an end part16. The end part16is an end portion of the semiconductor substrate10in the X axis and the Y axis. The valley part18is a predetermined portion including a portion having a smaller thickness than the center part14and the end part16. In the present example, a thickness T2of the semiconductor substrate10in the center part14is the maximum thickness of the semiconductor substrate10. The thickness T2of the semiconductor substrate10in the center part14may be the thickness at the center of the semiconductor substrate10. In addition, in the present example, a thickness T3of the semiconductor substrate10in the valley part18is the minimum thickness of the semiconductor substrate10. The thickness T3of the semiconductor substrate10in the valley part18may be the minimum thickness of the semiconductor substrate10in the valley part18. In addition, inFIG.3B, the average thickness of the semiconductor substrate10is denoted by T4, and is shown with a dotted line.

A grinding depth in the first grinding may be 50 μm or more. The grinding depth in the first grinding may be a difference between the average thickness T1of the semiconductor substrate10inFIG.3Aand the average thickness T4of the semiconductor substrate10inFIG.3B.

FIG.4shows an example of a relationship between the grinding depth in the first grinding S102and a Total Thickness Variation (TTV). The TTV is a difference between the maximum thickness and the minimum thickness in the semiconductor substrate10. That is, in the present example, the TTV is a difference between the thickness T2of the semiconductor substrate10in the center part14and the thickness T3of the semiconductor substrate10in the valley part18inFIG.3B. In addition, as used herein, an in-plane uniformity represents a processing uniformity of the semiconductor substrate10. The in-plane uniformity of the semiconductor substrate10inFIG.3Bis represented by (T2−T3)/T4, as an example.

Referring toFIG.4, the TTV is maintained at 2 to 4 μm by setting the grinding depth in the first grinding S102to 50 μm or more. Accordingly, by setting the grinding depth to 50 μm or more, the TTV after grinding can be maintained approximately constant regardless of the grinding depth. It is considered that the reason why the TTV after grinding can be maintained constant is because the grinding device stably operates by setting the grinding depth to 50 μm or more.

In addition, since the purpose of the first grinding S102is to remove the foreign substance30, the grinding depth in the first grinding S102is preferably not too large. For example, the grinding depth in the first grinding S102is preferably 200 μm or less. To summarize, the grinding depth in the first grinding S102may be 50 μm or more and 200 μm or less.

FIG.5AandFIG.5Billustrate examples of the protection tape cutting S103.FIG.5Aillustrates the protection tape20in the middle of flattening, in the protection tape cutting S103.FIG.5Billustrates the protection tape20after flattening, in the protection tape cutting S103. The protection tape20has a first surface21and a second surface22. The second surface22is a surface overlapping with (or a surface that contacts) the first surface11of the semiconductor substrate10. The first surface21is the surface on the opposite side of the second surface22.

In the protection tape cutting S103, the protection tape20is flattened. In the present example, the first surface21of the protection tape20is flattened, in the protection tape cutting S103. In the protection tape cutting S103, the second surface12of the semiconductor substrate10is supported by a table130. In addition, as shown inFIG.5A, in the protection tape cutting S103, the second surface22of the protection tape20is supported by the table130. In the present example, the second surface22of the protection tape20is supported by the table130via the semiconductor substrate10. In addition, in the protection tape cutting S103, the first surface21of the protection tape20is flattened with a flattening tool132. The flattening tool132is, for example, a tool having a blade cutting edge. In the protection tape cutting S103, a front surface of the protection tape20may be cut by bringing the blade cutting edge of the flattening tool132into contact with the protection tape20.

In the present example, the manufacturing method of the semiconductor device100includes the first grinding S102. Accordingly, the foreign substance30adhered to the second surface12of the semiconductor substrate10can be removed, and as shown inFIG.5B, a total thickness T5of the semiconductor substrate10and the protection tape20can be made constant. InFIG.5A, the total thickness T5of the semiconductor substrate10and the protection tape20is a difference between a height of the first surface21of the protection tape20and a height of the second surface12of the semiconductor substrate10. As a result, the in-plane uniformity of the semiconductor substrate10can be improved as compared to a case in which the first grinding S102is not included.

FIG.6illustrates an example of the table processing S104. In the table processing S104, a table140used in the second grinding S105is processed. The table140supports the first surface11of the semiconductor substrate10, in the second grinding S105. The table140has an upper surface141and a lower surface143. In the table processing S104, the table140used in the second grinding S105is processed based on an expected shape of the second surface12of the semiconductor substrate10after the first grinding S102. The expected shape of the second surface12of the semiconductor substrate10after the first grinding S102may be a shape that is assumed in advance. That is, it may be a shape of the second surface12of the semiconductor substrate10after performing the first grinding S102in the past. As an example, the table140is processed based on the TTV of the semiconductor substrate10that is expected after the first grinding S102. In addition, the shape of the second surface12may be predicted from the diameter of the whetstone122and the forward inclination angle of the whetstone122.

As an example, two portions in the XY plane of the semiconductor substrate10are regarded as a first substrate portion and a second substrate portion. In addition, in the table140used in the second grinding S105, a portion where the first substrate portion is placed, is regarded as a first table portion, and a portion where the second substrate portion is placed, is regarded as a second table portion. If the first substrate portion of the semiconductor substrate10is predicted to be thicker than the second substrate portion, a height of the upper surface141of the first table portion may be made higher than the height of the upper surface141of the second table portion. InFIG.6, a portion where the center part14of the semiconductor substrate10inFIG.3Bis placed, is regarded as a first table portion152. In addition, inFIG.6, a portion where the valley part18of the semiconductor substrate10inFIG.3Bis placed, is regarded as a second table portion154. The height of the upper surface141of the first table portion152may be made higher than the height of the upper surface141of the second table portion154. It should be noted that, the height of the upper surface141of the table140is the height from the lower surface143(reference) of the table140.

InFIG.4, it was described that the TTV after grinding can be maintained constant by setting the grinding depth in the first grinding S102to 50 μm or more. Accordingly, if the grinding depth in the first grinding S102is determined, the expected shape of the second surface12of the semiconductor substrate10after the first grinding S102can be determined. Therefore, a processing shape of the table140can be determined in advance based on the expected shape of the second surface12of the semiconductor substrate10after the first grinding S102. Therefore, the table processing S104can be performed in advance prior to the sticking S101. In addition, when grinding a plurality of the semiconductor substrates10in order using the table140, the table processing S104may be performed just once before grinding the plurality of semiconductor substrates10. That is, the sticking S101, the first grinding S102, the protection tape cutting S103, and the second grinding S105may be performed for each semiconductor substrate10, and the table processing S104may be commonly performed for the plurality of semiconductor substrates10.

The table140is, as an example, formed of a ceramic or metal material, and it may be a porous chuck table. The processing of the table140may be a general metal processing, or may be a grinding processing that is performed by bringing a whetstone into contact with a table. In the case of the grinding processing, a desired table shape can be obtained by adjusting the forward inclination angle of the whetstone. The whetstone used at this time may be the same as that used for the processing of a semiconductor substrate, or may be a different whetstone. The forward inclination angle will be described later usingFIG.17.

FIG.7AandFIG.7Billustrate examples of the second grinding S105.FIG.7Aillustrates the semiconductor device100before grinding, in the second grinding S105.FIG.7Billustrates the semiconductor device100after grinding, in the second grinding S105.

In the second grinding S105, the second surface12of the semiconductor substrate10is ground. In the second grinding S105, the protection tape20is supported by the table140. In addition, as shown inFIG.7A, in the second grinding S105, the first surface11of the semiconductor substrate10is supported by the table140. In the present example, the first surface11of the semiconductor substrate10is supported by the table140via the protection tape20. The table140may be a chuck table. In the table processing S104, the table140is processed based on the expected shape of the second surface12of the semiconductor substrate10after the first grinding S102, and thus the thickness of the semiconductor substrate10can be uniformized even if the thickness of the semiconductor substrate10is varied. In addition, in the second grinding S105, the second surface12of the semiconductor substrate10is ground with a whetstone142. The second grinding S105is, for example, performed using a grinding device such as a back grinder (BG). In the second grinding S105, the second surface12may be ground by inclining the whetstone142forward as in the case of the first grinding S102.

As shown inFIG.7B, after the second grinding S105, the semiconductor substrate10is processed to have a constant thickness T6. After the first grinding S102, the semiconductor substrate10is processed such that the center part14have a convex shape. However, in the present example, the table140used in the second grinding S105is processed based on the shape of the second surface12of the semiconductor substrate10after the first grinding S102, and thus the semiconductor substrate10can be flattened. Accordingly, the in-plane uniformity of the semiconductor substrate10can be improved.

In the present example, regarding the table140, in a portion144overlapping with the first surface11of the semiconductor substrate10, the height of the upper surface141monotonously decreases from a center part146of the portion144to an end part148of the region. That is, a height H1of the upper surface141of the table140in the center part146of the portion144may be the maximum among the height of the upper surface141of the table140in the portion144. InFIG.7AandFIG.7B, a boundary between the portion144and other portions of the table140is shown with a dotted line. The center part146of the portion144is a portion including the center of the portion144in the XY plane. The end part148is an end portion of the portion144in the X axis or the Y axis. It should be noted that, in the present example, the portion144is in contact with the first surface11of the semiconductor substrate10via the protection tape20. By allowing the table140to have such shape, the center part14of the semiconductor substrate10can be arranged relatively higher as compared to other portions. Accordingly, the center part14of the semiconductor substrate10can be largely ground as compared to other portions, and the in-plane uniformity of the semiconductor substrate10can be improved.

In the present example, in the second grinding S105, a convex part52is formed in the outer circumference of the semiconductor substrate10. That is, in the second grinding S105, in order to leave the convex part52in the outer circumference of the semiconductor substrate10, an inside of the convex part52is ground. By leaving the convex part52in the outer circumference, a ring-shaped reinforced structure can be left in the semiconductor substrate10. Accordingly, a warpage of the semiconductor substrate10can be suppressed after the second grinding S105. In addition, in processes after the second grinding S105, handling of the semiconductor substrate10is facilitated. To form the convex part52, an outer diameter D2of the whetstone142is preferably equal to or less than a radius of the semiconductor substrate10(half the diameter D1of the semiconductor substrate10).

In the present example, the average thickness of the semiconductor substrate10excluding the convex part52is denoted by T6. In addition, in the present example, the thickness of the semiconductor substrate10in the convex part52is denoted by T7. T7may be the maximum thickness of the semiconductor substrate10in the convex part52. The grinding depth in the second grinding S105may be a difference between T7and T6. The grinding depth in the second grinding S105may be 450 μm or more. That is, the grinding depth in the first grinding S102may be smaller than the grinding depth in the second grinding S105. Accordingly, in the second grinding S105, the semiconductor substrate10can be made thin.

FIG.8AandFIG.8Billustrate comparative examples of the second grinding S105.FIG.8Aillustrates the semiconductor device100before grinding, in the second grinding S105.FIG.8Billustrates the semiconductor device100after grinding, in the second grinding S105. InFIG.8AandFIG.8B, the shape of the table140is changed fromFIG.7AandFIG.7B. The shape of the table140inFIG.8AandFIG.8Bis flat, unlike inFIG.7AandFIG.7B.

InFIG.8B, after the second grinding S105, the thickness T6of the semiconductor substrate10is not uniform. This is because the shape of the semiconductor substrate10formed after the first grinding S102is remained in the second grinding S105. By processing the table140used in the second grinding S105, the shape of the semiconductor substrate10formed after the first grinding S102can be flattened.

FIG.9AandFIG.9Billustrate other examples of the first grinding S102.FIG.9Aillustrates the semiconductor device100before grinding, in the first grinding S102.FIG.9Billustrates the semiconductor device100after grinding, in the first grinding S102. InFIG.9AandFIG.9B, the shape of the table120is changed fromFIG.3AandFIG.3B.

In the present example, the table120used in the first grinding S102is processed such that the shape of the second surface12of the semiconductor substrate10after the first grinding S102is flattened. That is, the shape of the table120in the present example may be the same as the shape of the table140inFIG.6. Specifically, regarding the table120, in a portion124overlapping with the first surface11of the semiconductor substrate10, a height of the upper surface121monotonously decreases from a center part126of the portion124to an end part128of the portion124. The height of the upper surface121of the table120is the height of the table120from the lower surface123(reference). That is, a height H2of the upper surface121of the table120in the center part126of the portion124may be the maximum among the height of the upper surface121of the table120in the portion124. The center part126of the portion124is a predetermined portion including the center of the portion124in the X axis or the Y axis. The end part128is an end portion of the portion124in the X axis or the Y axis. By allowing the table120to have such shape, the center part14of the semiconductor substrate10can be made higher as compared to other portions. Accordingly, in the first grinding S102, the center part14of the semiconductor substrate10can be largely ground as compared to other portions, and the in-plane uniformity of the semiconductor substrate10can be improved.

FIG.10AandFIG.10Billustrate other examples of the second grinding S105.FIG.10Aillustrates the semiconductor device100before grinding, in the second grinding S105.FIG.10Billustrates the semiconductor device100after grinding, in the second grinding S105. InFIG.10AandFIG.10B, the shape of the table140is changed fromFIG.7AandFIG.7B.

In the present example, regarding the table140, in the portion144overlapping with the first surface11of the semiconductor substrate10, a valley part150is provided between the center part146of the portion144and the end part148of the portion144. The valley part150is a predetermined portion including a portion where the height of the upper surface141is lower than the center part146and the end part148. A height H3of the upper surface141of the table140in the valley part150may be lower than the height H1of the upper surface141of the table140in the center part146. The height H3of the upper surface141of the table140in the valley part150may be lower than a height H4of the upper surface141of the table140in the end part148. If the semiconductor substrate10has the valley part18between the center part14and the end part16as inFIG.3B, the in-plane uniformity of the semiconductor substrate10can be further improved by allowing the table140to have such shape.

The height H1of the upper surface141of the table140in the center part146of the portion144may be the highest among the height of the upper surface141of the table140in the portion144. By having such configuration, the center part14of the semiconductor substrate10can be arranged relatively higher as compared to other portions. Accordingly, the center part14of the semiconductor substrate10can be largely ground as compared to other portions, and the in-plane uniformity of the semiconductor substrate10can be improved.

The maximum value of the difference in heights of the upper surface141of the table140may be 0.005% or less of the diameter D1of the semiconductor substrate10. In the present example, the maximum value of the difference in the heights of the table140may be a difference between the height H1of the upper surface141of the table140in the center part146and the height H3of the upper surface141of the table140in the valley part150. That is, if the diameter D1of the semiconductor substrate10is 300 mm, the maximum value of the difference in the heights of the upper surface141of the table140may be 15 μm or less. In addition, the maximum value of the difference in the heights of the upper surface141of the table140may be 0.004% or less of the diameter D1of the semiconductor substrate10. If the diameter D1of the semiconductor substrate10is 200 mm, the maximum value of the difference in the heights of the upper surface141of the table140may be 8 μm or less. The point that the TTV is maintained at 2 to 4 μm by setting the grinding depth in the first grinding S102to 50 μm or more, is described above. However, practically, since there is a variation in machine accuracy, a difference of about double may be caused depending on the processing device performing the first grinding. In addition, even if the maximum value of the difference in the heights of the upper surface141of the table140has such range, the forward inclination angle of the whetstone142may be constant.

FIG.11illustrates another example of the manufacturing method of the semiconductor device100. InFIG.11, the manufacturing method of the semiconductor device100includes a table processing S205, a sticking S201, a first grinding S202, a protection tape cutting S203, an estimating S204, and a second grinding S206. The manufacturing method of the semiconductor device100inFIG.11is different from the manufacturing method of the semiconductor device100inFIG.1on the point that the estimating S204is provided after the protection tape cutting S203. That is, the table processing S205, the sticking S201, the first grinding S202, the protection tape cutting S203, and the second grinding S206inFIG.11may be the same as the table processing S104, the sticking S101, the first grinding S102, the protection tape cutting S103, and the second grinding S105inFIG.1, respectively.

FIG.12illustrates an example of the estimating S204. In the estimating S204, deterioration of the flattening tool132in the protection tape cutting S203is estimated. In the present example, since the manufacturing method of the semiconductor device100includes the first grinding S202, grinding dust in the first grinding S202may adhere to the protection tape20. If the protection tape cutting S203is performed while the grinding dust is adhered to the protection tape20, the flattening tool132is assumed to be deteriorated. In the present example, since the estimating S204is provided, deterioration of the flattening tool132can be estimated, and a replacement cycle and a maintenance cycle of the flattening tool132can be automatically determined. Accordingly, a defect in the protection tape cutting S203can be suppressed.

In the estimating S204, appearance information on the front surface of the protection tape20after the protection tape cutting S203is acquired, and deterioration of the flattening tool132in the protection tape cutting S203is estimated. In the present example, a device160acquires the appearance information on the first surface21of the protection tape20after the protection tape cutting S203.

The appearance information is, as an example, a reflectivity of the protection tape20. In the estimating S204, deterioration of the flattening tool132may be estimated by measuring a change in the reflectivity of the first surface21of the protection tape20after the protection tape cutting S203. From the study by the inventor of the present application, it was found that due to deterioration of the flattening tool132, the reflectivity of a visible light tends to monotonously decrease in the first surface21of the protection tape20after the protection tape cutting S203. Thus, a certain threshold may be set for the reflectivity, and the estimating S204may be a step for performing comparison between the reflectivity and the threshold.

In addition, the appearance information is, as an example, image information of the protection tape20. In this case, the device160may include a camera. The device160may perform an image analysis on the first surface21of the protection tape20. The device160may analyze an image contrast in the image analysis of the first surface21of the protection tape20. The device160may perform the image analysis and detect the density of grinding marks. That is, in the estimating S204, the density of the grinding marks on the first surface21of the protection tape20after the protection tape cutting S203may be measured, and deterioration of the flattening tool132may be estimated. From the study of the inventor of the present application, it was found that the density of the grinding marks tends to monotonously increase due to deterioration of the flattening tool132. Thus, a certain threshold may be set for the density of the grinding marks, and the estimating S204may be a step for performing comparison between the density of the grinding marks and the threshold.

It should be noted that, although the estimating S204is performed after the protection tape cutting S203in the present example, the estimating S204may be performed in the middle of the protection tape cutting S203. By performing the estimating S204in the middle of the protection tape cutting S203, deterioration of the flattening tool132in the middle of flattening can be estimated.

FIG.13illustrates a comparative example of the manufacturing method of the semiconductor device100. The manufacturing method of the semiconductor device100inFIG.13includes a sticking S301, a protection tape cutting S302, and a substrate grinding S303. Hereinafter, each step will be described inFIG.14toFIG.16C.

FIG.14illustrates an example of the sticking S301. The sticking S301inFIG.14may be the same as the sticking S201inFIG.2. Also in the present example, the foreign substance30is adhered to the second surface12of the semiconductor substrate10.

FIG.15AandFIG.15Billustrate examples of the protection tape cutting S302.FIG.15Aillustrates the protection tape20in the middle of flattening, in the protection tape cutting S302.FIG.15Billustrates the protection tape20after flattening, in the protection tape cutting S302. As in the case of the protection tape cutting S103inFIG.5AandFIG.5B, the protection tape20is flattened in the protection tape cutting S302.

In the present example, the foreign substance30remains adhered to the second surface12of the semiconductor substrate10. Accordingly, the semiconductor substrate10is supported by the table130while a portion overlapping with the foreign substance30being raised. If the protection tape20is flattened in this state, as shown inFIG.15B, a thickness T8of the protection tape20does not become constant. The thickness T8of the protection tape20is a difference between the height of the first surface21of the protection tape20and the height of the second surface22of the protection tape20. The protection tape20is processed such that it becomes concave near the portion where the foreign substance30is adhered.

FIG.16A,FIG.16B, andFIG.16Cillustrate examples of the substrate grinding S303.FIG.16Aillustrates the semiconductor device100before attachment to the table140, in the substrate grinding S303.FIG.16Billustrates the semiconductor device100after attachment to the table140, in the substrate grinding S303.FIG.16Cillustrates the semiconductor device100after grinding, in the substrate grinding S303.

InFIG.16A, before attachment to the table140, a space170exists between the table140and the protection tape20. InFIG.16B, after attachment to the table140, since the protection tape20is attached to the space170, the semiconductor substrate10is also retained such that the portion overlapping with the foreign substance30becomes concave. If the semiconductor substrate10is ground in this state, as shown inFIG.16C, the thickness T6of the semiconductor substrate10excluding the convex part52does not become constant.

The manufacturing method of the semiconductor device100inFIG.1includes the first grinding S102. Accordingly, the foreign substance30adhered to the second surface12of the semiconductor substrate10can be removed. The in-plane uniformity of the semiconductor substrate10can be improved as compared to the manufacturing method of the semiconductor device100inFIG.13.

FIG.17illustrates a forward inclination angle θ1. InFIG.17, the first grinding S102in a YZ plane is shown. The lower surface of the whetstone122is arranged to have the forward inclination angle θ1with respect to the Y axis direction. In addition, also in the second grinding S105, the lower surface of the whetstone142is arranged to have a forward inclination angle with respect to the Y axis direction. The forward inclination angle of the whetstone142in the second grinding S105is denoted by θ2(not shown).

The forward inclination angle θ2of the whetstone142in the second grinding S105may be smaller than the forward inclination angle θ1of the whetstone122in the first grinding S102. In addition, the forward inclination angle θ2of the whetstone142in the second grinding S105may be the same as the forward inclination angle θ1of the whetstone122in the first grinding S102. The forward inclination angle θ2of the whetstone142in the second grinding S105may be larger than the forward inclination angle θ1of the whetstone122in the first grinding S102.