Ultrasonic vibration device, ultrasonic cleaning device, cleaning method, and method for manufacturing a semiconductor device

Abstract

This invention provides a technology capable of removing foreign matter from objects to be cleaned. [Solution] A technology is provided comprising a vibrating element section including a transducer that generates ultrasonic vibrations, a horn section attached to the lower part of the vibrating element section, a mounting section for attaching the vibrating element section and the horn section, and a cooling mechanism for cooling the mounting section.

Description

Technical Field

[0001] The present disclosure relates to an ultrasonic vibration device, an ultrasonic cleaning device, a cleaning method, and a method for manufacturing a semiconductor device.

Background Art

[0002] As a cleaning device shown in Patent Document 1, there may be a proposed technique of irradiating ultrasonic waves from the back side of an object to be cleaned for cleaning.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure aims to provide a technique capable of removing foreign substances on an object to be cleaned.

Means for Solving the Problems

[0005] According to one aspect of the present disclosure, a vibration element part including a vibrator that generates ultrasonic vibration, a horn part attached to the lower part of the vibration element part, a mounting part for mounting the vibration element part and the horn part, and a cooling mechanism for cooling the mounting part are provided.

Effects of the Invention

[0006] According to the present disclosure, it is possible to remove foreign substances on an object to be cleaned.

Brief Description of the Drawings

[0007] [Figure 1] It is a schematic diagram showing an example of an ultrasonic cleaning device which is an embodiment of the present disclosure. [Figure 2] This is a schematic diagram showing an example of an ultrasonic vibration device that is an embodiment of the present disclosure. [Figure 3] This is an example of a detailed view of the lower part of an ultrasonic vibration device, which is an embodiment of the present disclosure. [Figure 4] This is an example of a cooling mechanism for an ultrasonic vibration device, which is an embodiment of the present disclosure. [Figure 5] This figure shows an example of an ultrasonic cleaning apparatus according to the present disclosure. [Figure 6] This figure illustrates an embodiment of the present disclosure that uses ultrasonic irradiation by a transducer. [Modes for carrying out the invention]

[0008] <One aspect of this disclosure> The following description will explain one aspect of this disclosure, primarily with reference to Figures 1 to 6. It should be noted that the drawings used in the following description are schematic, and the dimensional relationships and proportions of the elements shown in the drawings do not necessarily correspond to those of reality. Furthermore, the dimensional relationships and proportions of the elements do not necessarily correspond between multiple drawings.

[0009] The ultrasonic cleaning apparatus (hereinafter referred to as the cleaning apparatus) 10 shown in Figure 1 has the following configuration. Specifically, 1 is a processed object to be cleaned, such as a semiconductor wafer, and 2 is a processed object (for example, a pattern) on which foreign matter is attached to the surface of the object to be cleaned 1. 3 and 4 are the transducer 101 in this embodiment, where 3 is a vibrating element such as a piezoelectric element, and 4 is an electrode. A horn section 102 made of a vibration transmitting material is attached to the lower part of the transducer 101. 5 is an ultrasonic oscillator that supplies high-frequency power to the transducer 101 and is connected by a cable 103 made of a power cable or the like. 6 is a cleaning tank for cleaning, and the cleaning tank 6 is filled with cleaning liquid 7. The lower part of the horn section 102 is immersed in this cleaning liquid 7. By driving the transducer 101 with the ultrasonic oscillator 5, the generated ultrasonic vibrations propagate through the cleaning liquid 7 via the horn section 102, and foreign matter attached to the object to be cleaned 1 (more specifically, the processed object 2) can be removed.

[0010] As shown in Figure 1, the cleaning device 10 has a stage STG on which the object to be cleaned 1 can be placed. However, this is merely an example and is not limited to this configuration.

[0011] The ultrasonic vibration device 100 shown in Figure 2 corresponds to an example configuration including the drive part of the transducer 101 provided in the ultrasonic cleaning device 10, and has the following configuration. Specifically, 104 is a vibration element section that serves as an ultrasonic generating unit for generating ultrasonic waves. The vibration element section 104 includes a transducer 101 (vibration element 3, electrode 4), a backing plate 107 as an adjustment plate, and a front plate 108. When power is applied to the vibration element 3 from the ultrasonic oscillator 5 via the plate-shaped electrode 4, it expands and contracts, and this expansion and contraction vibration is transmitted to the horn section (vibration transmission material) 102. In Figure 2, the vibration element 3 is sandwiched between electrode plates 4 (3 plates). A discharge resistor 106 for discharging the power charged in the transducer 101 may also be included in the vibration element section 104. 105 is a cover that houses the vibration element section 104, and includes an upper cover 105a and a lower cover 105b. The lower part of the horn section 102 is immersed in the cleaning solution 7, and ultrasonic waves are propagated to the object to be cleaned 1 through this horn section 102. Although not shown in the diagram, due to the transmission characteristics of ultrasonic waves, ultrasonic vibrations pass through the cleaning solution 7, generating ultrasonic vibrations in the object to be cleaned 1, making it possible to remove foreign matter from the object to be cleaned 1.

[0012] As shown in Figure 2, the ultrasonic vibration device 100 as a transducer unit has a cover 105 on which a vibration element section 104 containing a transducer 101 that generates ultrasonic vibrations is provided, and a horn section 102 attached to the lower part of the vibration element section 104, with the diameters of the vibration element section 104 (especially the transducer 101) and the horn section 102 being the same. With this configuration, ultrasonic vibrations can be generated only in the vertical direction, making adjustments easy. Therefore, it is expected that uneven cleaning of the object to be processed 1 will be eliminated.

[0013] Generally, the diameter of the horn section 102 is made the same as, or close to the same as, the size of the vibrating element section 104, in order to match the size of the object to be cleaned 1. Therefore, the horn section 102 is shaped like a trumpet (with the output side widening towards the bottom). However, with such a shape, the ultrasonic waves emitted from the horn section 102 are generated not only in the vertical direction but also in the horizontal direction, causing the intensity to be dispersed.

[0014] Furthermore, as shown in Figure 2, the tip of the horn portion 102 protrudes from the lower end of the cover 105 (lower part 105b of the cover). Specifically, the tip of the horn portion 102 protrudes from the cover 105 (lower part 105b of the cover) so that only the tip of the horn portion 102 is immersed in the liquid to clean the object to be processed 1 (for example, a wafer with a pattern on its surface). This prevents the cover 105 from being immersed in the cleaning liquid 7. This is because if the cover 105 is immersed in the cleaning liquid 7, air bubbles will accumulate, which will negatively affect the propagation of ultrasonic waves.

[0015] For example, the vibrating element 3 may be a PZT element made of lead zirconate titanate (hereinafter referred to as PZT). Furthermore, for example, the vibration transmitting material 102 transmits the vibration of the vibrating element 3, and it is desirable that it be made of a material that has high ultrasonic wave propagation properties, does not generate dust due to deterioration during use, and does not release metallic components.

[0016] As shown in Figure 2, adjustment plates 107, 108, etc., are used to set the connection between the vibrating element 104 and the horn 102 to be an antinode of ultrasound. This configuration maximizes the intensity of the ultrasound (vibration) at the mounting portion 128, which is the boundary where the vibrating element 104 and the horn 102 are attached. Therefore, as shown in Figure 2, a cooling mechanism 120 is provided to cool the vibrating element 104 and the mounting portion 128. The cooling mechanism 120 will be described later.

[0017] FIG. 3 is a diagram showing the attachment details of the flange portion 102a. The flange portion 102a is fixed to the cover 105 (lower cover 105b) via a buffer material 110 (110a, 110b, 110c, 110d) which is a resin member such as a packing or an O-ring. Therefore, the flange portion 102a is configured not to directly contact the cover 105 (lower cover 105b). Since the metal parts are not in contact with each other through the O-ring 110, the loss of vibration energy due to frictional heat energy is reduced at the connection part (fixing part) between the flange portion 102a and the cover 105 (lower cover 105b). Note that the buffer material (O-ring) 110 may be an elastic member used in rubber products such as silicone rubber as long as its coefficient of friction is small enough not to hinder the vibration energy.

[0018] As shown in FIG. 3, there is a horn nut 111 as a pressing portion for holding the flange portion 102a from below, and the lower cover 105b provided to cover the flange portion 102a from above and the pressing portion 111 are configured to fix the flange portion 102a via the buffer material 110. Specifically, grooves for O-rings are formed above and below the flange portion 102a, and a horn in which the O-rings 110a and 110b are assembled to the cover 105 (lower cover 105b) is pressed against, and the O-rings 110c and 110d are assembled by screwing the pressing portion 111 into the lower cover 105b. With such a configuration, the horn portion 102 is prevented from falling. And when the flange portion 102a is fixed by the lower cover 105b and the pressing portion 111, it is configured such that the length from the end of the horn portion 102 to the flange portion 102a is set. With such a configuration, the flange portion 102a can be made into a compact shape.

[0019] Furthermore, in the case of screwing, it is necessary to pass a screw hole for inserting a screw to the outside, and it is necessary to enlarge the flange portion 102a. However, if the flange portion 102a is large, the edge of the flange vibrates greatly due to the lever principle, resulting in a large heat loss.

[0020] Furthermore, by using an elastic member 110 such as an O-ring as a buffer, the lower part of the cover 105b and the pressing part 111 become point contacts rather than surface contacts, thus increasing the pressure on the sealing surface, making leaks less likely and improving airtightness. Generally, cleaning fluid 7 uses flammable chemicals, so there is a risk of ignition if the cleaning fluid 7 enters the cover 105. However, with this configuration, in the ultrasonic vibration device 100 of this embodiment, even if the lower part of the cover 105b is immersed in the cleaning fluid 7 due to a malfunction, there is no risk of the cleaning fluid 7 entering the vibration element part 104 inside the cover 105.

[0021] As shown in Figure 2, adjustment plates 107, 108, etc. are used to set the connection between the vibrating element 104 and the horn 102 so that it becomes an antinode of the ultrasound. The position where the flange portion 102a of the horn 102 is fixed to the cover 105 becomes a node of the ultrasound, and the tip of the horn 102 is set so that it becomes an antinode of the ultrasound.

[0022] Specifically, the device is configured such that the intensity of the ultrasonic waves (vibrations) is smallest at the position where the flange portion 102a and the cover 105 are fixed, and the end of the horn portion 102 is positioned where the intensity of the ultrasonic waves (vibrations) propagated from the vibrating element portion 104 is greatest.

[0023] In other words, at the point where two different materials are joined, they vibrate against each other, generating frictional heat. This causes the vibrational energy from the ultrasound to be consumed as thermal energy. To reduce this thermal energy loss due to frictional heat, the system is configured to minimize the vibrational energy from the ultrasound. In this embodiment, a resin component (O-ring) is used, but any component with a low surface friction coefficient that can be fixed in place will suffice.

[0024] On the other hand, since ultrasonic waves must be propagated from the tip of the horn section 102 to the object to be cleaned 1, the tip of the horn section 102 is configured to have the highest vibration energy due to the ultrasonic waves. The vibration energy at the tip of the horn section 102 at this time can be increased by reducing the thermal energy loss at the position where the flange section 102a and the cover 105 are fixed. In other words, if these thermal energy losses are large, even if ultrasonic waves can be propagated to the object to be cleaned 1, the object to be cleaned 1 may not be cleaned due to insufficient vibration energy. On the other hand, the mounting section 128, which serves as a connection point to which the vibration element section 104 and the horn section 102 are connected, tends to have large thermal energy losses due to frictional heat, resulting in low vibration energy.

[0025] According to this embodiment, as described above, if the diameter of the vibration element section 104 (especially the transducer 101) and the diameter of the horn section 102 are the same, vibration occurs only in the vertical direction (even if lateral vibration occurs, it is so small that it does not need to be considered), thus enabling adjustment of vibration energy by position. Furthermore, with this configuration, the irradiation of ultrasonic waves from the transducer 101 can be made uniform.

[0026] In the case of cleaning at low frequencies, repeated force acts on the vibrating surface, causing gradual wear (erosion). As this erosion progresses, holes (pinholes) form in the vibrating surface (the tip of the horn section 102), allowing the cleaning fluid 7 to enter the transducer unit and cause malfunction. To counteract this erosion, as shown in Figure 3, the tip of the horn section 102 (especially the part immersed in the cleaning fluid 7) is subjected to surface treatment (coating) 121 such as chrome plating or DLC coating to increase durability. Specifically, the coating 121 is applied up to the flange section 102a.

[0027] The cooling mechanism 120 will be described using Figure 4. The cooling mechanism 120 includes a refrigerant injection mechanism 125. The lower part of Figure 4 shows a conceptual plan view of the refrigerant injection mechanism 125 as seen from above. The refrigerant injection mechanism 125 is configured to spray refrigerant 250 from a supply hole 125a, which acts as an injection part, onto the mounting part 128. The cooling mechanism 120 also has an introduction pipe (introduction part) 125b for introducing refrigerant 250 into the cover 105, and a supply pipe (supply part) 125c that surrounds the mounting part 128. The supply part 125c has a plurality of injection parts 125a, and these injection parts 125a are open toward the mounting part 128. The injection parts 125a are provided at equal intervals in the flow direction of the supply part 125c. The supply hole 125a, introduction part 125b, and supply part 125c may be collectively referred to as the refrigerant injection mechanism 125. With this configuration, a large amount of refrigerant 250 can be supplied to the mounting portion 128 between the vibrating element 104 and the horn portion 102, and since the injection portions 125a are evenly arranged to surround the mounting portion 128, the mounting portion 128 can be cooled uniformly by the refrigerant 250.

[0028] The cooling mechanism 120 has an exhaust section 127 which serves as an exhaust port for exhausting the refrigerant 250 from inside the cover 105. As described above, the supply section 125c is positioned to blow directly onto the mounting section 128 between the vibrating element section 104 and the horn section 102, and the exhaust section 127 is positioned at the upper end of the vibrating element section 104. In other words, the vibrating element section 104 is positioned between the exhaust section 127 and the supply section 125c. This allows the vibrating element section 104 to be efficiently cooled by the refrigerant 250. Specifically, the vibrating element 3 can be efficiently cooled by the refrigerant 250 flowing into the exhaust section 127. In short, the ultrasonic vibration device 100 includes a vibrating element section 104 containing a transducer 101 that generates ultrasonic vibrations, a horn section 102 attached to the lower part of the vibrating element section 104, a mounting section 128 for attaching the vibrating element section 104 and the horn section 102, and a cooling mechanism 120 for cooling the mounting section 128. Furthermore, the ultrasonic cleaning apparatus 10 includes an ultrasonic vibrator 100, an ultrasonic oscillator for driving the transducer 101, and a cleaning tank 6 in which the object to be cleaned 1 is placed and which is filled with cleaning liquid 7.

[0029] (Examples) The horn-type ultrasonic transducer in this embodiment will be explained using Figure 5. As shown in Figure 5, there is only one transducer 101. In Figure 5, the ultrasonic waves emitted from the transducer 101 are transmitted to the object to be cleaned 1 by ultrasonic irradiation from the surface side of the object to be cleaned 1, thereby directly vibrating the object to be cleaned 1 (workpiece 2).

[0030] In this embodiment, an example of the ultrasonic vibration device 100 is one in which the diameter of the transducer 101 is, for example, 30 mm and the diameter of the horn section 102 is, for example, 30 mm. When the output from the high-frequency generator 5 is, for example, 100 W, the ultrasonic intensity is, for example, 14.2 W / cm2. Furthermore, because the ultrasonic intensity is higher than that of the comparative example, it can have cleaning power on the object to be cleaned 1.

[0031] Here, if the object to be cleaned 1 is a semiconductor wafer, as shown in Figure 5, the transducer 101 is positioned on the surface side of the object to be cleaned 1, and ultrasonic waves are irradiated from the top (surface side) of the object to be cleaned 1, which allows for efficient cleaning of the workpiece 2 on the surface of the object to be cleaned 1. Specifically, the workpiece 2 can be vibrated with strong force, and deposits adhering to deep grooves (trenches) formed in the workpiece 2 can be removed. In other words, the cleaning method using the ultrasonic cleaning device 10 is a cleaning method that vibrates the object to be cleaned 1 by transmitting ultrasonic waves emitted from the transducer 101 through the object to be cleaned 1 through ultrasonic irradiation from the surface side of the object to be cleaned 1. Furthermore, the method for manufacturing a semiconductor device includes the steps of preparing the ultrasonic cleaning device 10, performing fine processing on the surface of the semiconductor wafer 1, and vibrating the semiconductor wafer 1, which is the object to be cleaned, by transmitting ultrasonic waves emitted from the transducer 101 through the semiconductor wafer through ultrasonic irradiation from the surface side of the semiconductor wafer 1.

[0032] However, if the object to be cleaned 1 is a semiconductor wafer, the diameter of the semiconductor wafer is approximately 150 mm to 300 mm, and because the diameter of the transducer 101 is small, it is not possible to remove all of the deposits adhering to the semiconductor wafer in a single cleaning. Therefore, it is necessary to clean it multiple times while changing the location. Although it does not need to be specifically described, the ultrasonic vibration device 100 can be moved up, down, left, and right by a transport mechanism not shown in the figure. Accordingly, as shown in Figure 6 later, although the number of measurement points may increase and it may take time, it is possible to clean even processed objects 2 that have evolved in recent years without any omissions.

[0033] Furthermore, if the object to be cleaned 1 is a semiconductor wafer, the transducer 101 will be moved and cleaned repeatedly. An example of the ultrasonic irradiation range in this case is shown in Figure 6. Figure 6 shows the irradiation range after 41 repetitions of movement and cleaning. It is shown as the irradiation area S0 of the transducer 101 in one cycle. In this way, by repeating the movement of the transducer 101 and ultrasonic cleaning multiple times, the surface of the object to be cleaned 1 can be cleaned evenly.

[0034] In the future, to reduce damage to processed products such as semiconductor wafers caused by ultrasonic irradiation, it will be necessary to use higher frequencies that minimize cavitation in the cleaning solution caused by ultrasound. The technology disclosed in this disclosure is in line with this trend. Here, cavitation is caused by the expansion and compression of the cleaning solution by ultrasound, and its force depends on the frequency and intensity of the ultrasound.

[0035] As described above, this embodiment provides at least one of the following effects (a) to (f).

[0036] (a) According to this embodiment, since the diameter of the vibrating element portion 104 (transducer 101) and the diameter of the horn portion 102 are the same, ultrasonic waves with only longitudinal vibrations can be generated. Therefore, the length of the flange portion 102a and the tip of the horn portion 102 can be adjusted so that the tip of the horn portion 102 has the maximum vibration energy. This makes it possible to clean the object to be cleaned 1 placed in the cleaning liquid 7 uniformly without uneven cleaning.

[0037] (b) According to this embodiment, since the horn portion 102 protrudes more than the cover 105, even if the tip of the horn portion 102 is immersed in the cleaning solution 7, the cover 105 is not immersed in the cleaning solution 7. Therefore, the object to be cleaned 1 placed in the cleaning solution 7 can be cleaned without the accumulation of air bubbles caused by the cover 105.

[0038] (c) According to this embodiment, an adjustment plate is provided so that the joint between the vibrating element 104 and the horn 102 has the minimum vibration energy, and the length of the flange 102a and the tip of the horn 102 can be adjusted so that the joint between the flange 102a and the cover 105 has the minimum vibration energy. This reduces energy loss due to frictional heat generated by vibration.

[0039] (d) According to this embodiment, a cooling mechanism 120 is provided that focuses on cooling the boundary (mounting portion) 128 between the vibrating element 104 and the horn portion 102. This makes it possible to suppress frictional heat generated by vibration. In particular, since the boundary 128 between the vibrating element 104 and the horn portion 102 is the part where energy is generated due to frictional heat, the structure is such that a coolant can be blown onto it from the surroundings, and the boundary 128 can be cooled evenly and uniformly. Thus, energy loss due to frictional heat can be suppressed.

[0040] (e) According to this embodiment, grooves are machined above and below the flange portion 102a, and a cushioning member is placed in these grooves, thereby preventing metal-to-metal contact at the connection between the flange portion 102a and the cover 105. This reduces energy loss due to frictional heat generated by vibration.

[0041] (f) According to this embodiment, since ultrasonic waves are irradiated by a single transducer 101 having the same diameter as the vibrating element portion 104 (transducer 101) and the horn portion 102, the object to be cleaned 1 placed in the cleaning solution 7 can be cleaned without unevenness. Furthermore, according to this embodiment, even if the object to be cleaned 1 is a semiconductor wafer having a pattern on its surface, it can be cleaned without unevenness.

[0042] Although the above has been described in detail based on this embodiment, it goes without saying that the embodiment and examples are not limited to those described above and can be modified in various ways. For example, this embodiment can be applied to applications that utilize the characteristics of ultrasonic wave propagation in air, regardless of whether the application is in a liquid, by utilizing the effects expected from high-frequency ultrasound. In the above case as well, the same effects as those of the above embodiment and examples can be obtained.

[0043] Furthermore, as an application example of this embodiment, a cooler to suppress heat generation of the transducer 101 may be installed inside the cover 105. In this case as well, the same effects as those of the above embodiment and example can be obtained.

[0044] Furthermore, although the above-described embodiments described an ultrasonic cleaning apparatus for cleaning microfabricated products such as semiconductor wafers, this disclosure is not limited to semiconductor manufacturing equipment and can also be applied to ultrasonic cleaning apparatuses for cleaning glass substrates such as liquid crystal display (LCD) devices. In the above cases as well, the same effects as those of the above embodiments and examples can be obtained. [Explanation of Symbols]

[0045] 100: Ultrasonic vibration device 101: Oscillator 102: Horn section (vibration transmission section) 104: Vibration element section (ultrasonic generating section) 105: Cover 120: Cooling mechanism 128: Mounting part.

Claims

1. A vibrating element section including a transducer that generates ultrasonic vibrations, A horn portion is attached to the lower part of the vibration element portion, The mounting portion for attaching the vibration element portion and the horn portion, An ultrasonic vibration device having a cooling mechanism for cooling the mounting portion.

2. The ultrasonic vibration device according to claim 1, wherein the cooling mechanism is configured to spray a refrigerant onto the mounting portion.

3. Furthermore, the vibration element portion has a cover that is provided inside, The cooling mechanism includes an introduction section for introducing a refrigerant into the cover, A supply unit is provided so as to surround the aforementioned mounting portion, The ultrasonic vibration device according to claim 1, comprising:

4. The supply unit has a plurality of injection units, The ultrasonic vibration device according to claim 3, wherein the injection portion is open toward the mounting portion.

5. The ultrasonic vibration device according to claim 4, wherein the injection units are provided at equal intervals in the flow path direction of the supply unit.

6. Furthermore, it has an exhaust section for exhausting the refrigerant from inside the cover, The ultrasonic vibration device according to claim 3, wherein the vibration element is positioned between the exhaust unit and the supply unit.

7. The ultrasonic vibration device according to claim 1, wherein the mounting portion to which the vibration element portion and the horn portion are connected is configured such that the intensity of the ultrasonic waves propagated from the vibration element portion is reduced.

8. The ultrasonic vibration device according to claim 1, configured such that the end of the horn portion is located at the position where the strength of the ultrasonic waves propagated from the vibrating element portion is greatest.

9. Furthermore, the vibration element portion has a cover that is provided inside, The ultrasonic vibration device according to claim 1, wherein the tip of the horn portion protrudes from the lower end of the cover.

10. Furthermore, it has a flange portion that is fixed to the cover via a cushioning material, The ultrasonic vibration device according to claim 9, wherein the flange portion is configured not to directly contact the cover.

11. The ultrasonic vibration device according to claim 10, wherein the position where the flange portion and the cover are fixed is configured such that the strength of the ultrasonic waves propagated from the vibration element portion is minimized.

12. The ultrasonic vibration device according to claim 1, An ultrasonic oscillator for driving the transducer, A cleaning tank in which the object to be cleaned is placed and filled with cleaning solution, An ultrasonic cleaning device equipped with the following features.

13. The ultrasonic cleaning apparatus according to claim 12, wherein the horn portion is configured to be immersed in the cleaning solution.

14. The ultrasonic cleaning apparatus according to claim 12, wherein the object to be cleaned is a semiconductor wafer.

15. A cleaning method using the ultrasonic cleaning apparatus described in claim 12, A cleaning method that causes the object to be cleaned to vibrate by irradiating the object with ultrasonic waves from the surface side of the object to be cleaned, thereby transmitting ultrasonic waves emitted from the transducer through the object to be cleaned.

16. A step of preparing the ultrasonic cleaning apparatus according to claim 14, A step of performing fine processing on the surface of the semiconductor wafer, The process of vibrating the semiconductor wafer by transmitting ultrasonic waves emitted from the transducer through the semiconductor wafer by irradiating the semiconductor wafer with ultrasonic waves from the surface side of the semiconductor wafer, A method for manufacturing a semiconductor device having [a certain feature].

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