Inspection wafer and method for manufacturing inspection wafer

Abstract

To provide an inspection wafer and an inspection wafer manufacturing method that make it possible to quantitatively verify the performance evaluation of a cleaning function.SOLUTION: An inspection wafer manufacturing method includes: a heating plate placing step of providing an inspection wafer W having a first surface Wa and a second surface Wb and having dust particles S adhering to at least the first surface Wa, and placing the second surface Wb on a heating plate 40 with the first surface Wa of a wafer W exposed; and a dust adhesion step of spraying liquids L1 and L2 mixed with the dust particles S onto the first surface Wa to make the dust particles S adhere thereto, heating the wafer W with the heating plate 40, and forming a dust particle layer.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] A wafer with multiple devices such as ICs and LSIs formed on its surface and partitioned along planned dividing lines has its back surface ground by a grinding machine to form it to the desired thickness, and then is divided into individual device chips by a cutting machine for use in electrical devices such as mobile phones and personal computers.

[0003] Furthermore, grinding devices and cutting devices are equipped with a cleaning function, and ground or cut wafers are cleaned appropriately (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-003611 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-036275 Summary of the Invention [Problem to be solved by the invention]

[0005] However, until now, there has been no method for appropriately evaluating the cleaning capacity of the cleaning functions installed in grinding machines and cutting machines, and there has been a problem in that it has not been possible to objectively evaluate the extent to which factors such as the flow rate and pressure of the cleaning water, the mixing state of the cleaning water and gas, the rotation speed of the spinner table, the shape of the cleaning nozzle, and the oscillation speed of the cleaning nozzle affect cleaning power, thereby finding conditions that provide high cleaning effectiveness, or comparing the cleaning effectiveness with that of the cleaning functions of other companies' products.

[0006] The present invention has been made in consideration of the above-mentioned facts, and its main technical object is to provide an inspection wafer and a manufacturing method of the inspection wafer that enable quantitative verification of performance evaluation of the cleaning function. [Means for solving the problem]

[0007] In order to solve the above-mentioned main technical problem, according to the present invention, It is used to evaluate the cleaning effect of the cleaning function of the cleaning means disposed in the grinding device, A dust collector having a first surface and a second surface, and dust attached to at least the first surface. The dust is a wafer for inspection, and the dust is grinding chips discharged when a grinding process is carried out by a grinding device that grinds a wafer of the same quality as the dust. A test wafer is provided. Furthermore, according to the present invention, there is provided an inspection wafer that is used to evaluate the cleaning effect of the cleaning function of a cleaning means disposed in a cutting device, the inspection wafer having a first surface and a second surface and having dust attached to at least the first surface, the dust being cutting chips discharged when cutting processing is carried out by a cutting device that cuts a wafer of the same quality as the dust.

[0009] It is preferable that the first surface has a plurality of regions formed thereon, each region having a different amount of accumulated dust.It is also preferable that the first surface has grooves formed thereon.

[0010] In order to solve the above-mentioned main technical problem, according to the present invention, Used to evaluate the cleaning effect of the cleaning function of the cleaning means disposed in the grinding or cutting device. A method for manufacturing an inspection wafer, comprising: a heating plate placing step of exposing a first surface of a wafer to a heating plate and placing the second surface of the wafer on the heating plate; and a dust adhering step of spraying a dust-mixed liquid onto the first surface to cause the dust to adhere, and heating the wafer with the heating plate to form a dust layer. The dust is grinding chips discharged when a grinding process is performed by a grinding device that grinds wafers of the same quality as the dust, or cutting chips discharged when a cutting process is performed by a cutting device that cuts wafers of the same quality as the dust. A method for manufacturing a test wafer is provided.

[0011] In the dust adhesion step, it is preferable to form the dust layer multiple times, and the dust is preferably of the same quality as the wafer. [Effects of the Invention]

[0012] The inspection wafer of the present invention comprises: It is used to evaluate the cleaning effect of the cleaning function of the cleaning means disposed in the grinding device, A dust collector having a first surface and a second surface, and dust attached to at least the first surface. The dust is a wafer for inspection, and the dust is grinding chips discharged when a grinding process is carried out by a grinding device that grinds a wafer of the same quality as the dust. A test wafer is provided. According to the present invention, there is also provided a test wafer used to evaluate the cleaning effect of the cleaning function of a cleaning means disposed in a cutting device, the test wafer having a first surface and a second surface and dust attached to at least the first surface, the dust being chips discharged when cutting is performed by a cutting device that cuts a wafer of the same quality as the dust.Therefore, by using a test wafer, it becomes possible to easily verify the cleaning effect of the cleaning function. That is, it becomes possible to find the conditions with the highest cleaning effect by changing the flow rate and pressure of the cleaning water, the mixture of the cleaning water and gas, the rotation speed of the spinner table, the shape of the cleaning nozzle, the oscillation speed of the cleaning nozzle, etc., and to make an objective judgment by comparing the cleaning effect with that of the cleaning function of other companies' products.

[0013] Furthermore, the method for manufacturing an inspection wafer of the present invention includes the steps of: Used to evaluate the cleaning effect of the cleaning function of the cleaning means disposed in the grinding or cutting device. A method for manufacturing an inspection wafer, comprising: a heating plate placing step of exposing a first surface of a wafer to a heating plate and placing the second surface of the wafer on the heating plate; and a dust adhering step of spraying a dust-mixed liquid onto the first surface to cause the dust to adhere, and heating the wafer with the heating plate to form a dust layer. The dust is grinding chips discharged when a grinding process is performed by a grinding device that grinds wafers of the same quality as the dust, or cutting chips discharged when a cutting process is performed by a cutting device that cuts wafers of the same quality as the dust. This makes it possible to appropriately manufacture the above-mentioned inspection wafer. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2A is an overall perspective view of a grinding device, and FIG. 2B is an overall perspective view of a cutting device. [Figure 2] FIG. 2 is a perspective view of a wafer for testing and a heating plate. [Figure 3] FIG. 10 is a perspective view showing an embodiment of a dust adhesion step. [Figure 4] 1 is a perspective view of a test wafer having a first surface on which a plurality of regions with different amounts of dust accumulation are formed; [Figure 5] FIG. 10 is a perspective view of three test wafers with different amounts of dust accumulation. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an inspection wafer and a manufacturing method for an inspection wafer configured based on the present invention will be described in detail with reference to the accompanying drawings.

[0016] The test wafer realized by this embodiment is a wafer that reproduces a wafer that requires cleaning due to, for example, grinding dust or cutting dust adhering to its surface. Therefore, in order to adhere the dust necessary for the reproduction to the test wafer, the post-grinding wastewater L1 obtained from the grinding apparatus 1 shown in FIG. 1(a) or the post-cutting wastewater L2 obtained from the cutting apparatus 3 shown in FIG. 1(b) is used. The wafer 20 processed by the grinding apparatus 1 and the cutting apparatus 3 is a silicon (Si) wafer having a front surface 20a on which devices and the like are formed and a back surface 20b on which devices and the like are not formed. The base wafer forming the test wafer is also made of the same silicon (Si) quality.

[0017] 1(a) shows a grinding apparatus 1. The grinding apparatus 1 has a roughly rectangular parallelepiped apparatus housing 10, and on the apparatus housing 10, there are: a grinding means 16 for grinding a workpiece (wafer 20), a chuck table 15 for holding the wafer 20, a first cassette 12a arranged on the front side in the drawing for accommodating the wafer 20 before grinding; a second cassette 12b arranged on the other side in the Y-axis direction in the drawing with respect to the first cassette 12a for accommodating the wafer 20 after grinding; a temporary placement means 13 arranged adjacent to the first cassette 12a in the X-axis direction in the drawing for aligning the center of the wafer 20; The wafer transfer system includes a cleaning means 19 disposed adjacent to the first cassette 12a, a first transport means 11 that transports the wafers 20 stored in the first cassette 12a to the temporary storage means 13 and transports the wafers 20 cleaned by the cleaning means 19 to the second cassette 12b, a second transport means 14 that transports the wafers 20 placed on the temporary storage means 13 and centered onto a chuck table 15 positioned at a carry-in / out position (the front side in the drawing), and a third transport means 18 that transports the wafers 20 after grinding from the chuck table 15 positioned at the carry-in / out position to the cleaning means 19.

[0018] The grinding means 16 is mounted on the inner surface of a support wall 10a erected at the rear end of the housing 10 so as to be movable up and down. The grinding means 16 has a grinding wheel with a circularly arranged grinding stone 162, and the grinding wheel is rotated by an electric motor or the like. The grinding means 16 is moved back and forth in the Z-axis direction (up and down) indicated by the arrow Z in the figure by a grinding feed mechanism 17. A grinding water supply means (not shown) is connected to the grinding means 16. After being used in the grinding process, the pure water supplied from the grinding water supply means is guided to a drain port 10b formed on the top surface of the housing 10 together with grinding chips D1 generated by the grinding process, discharged through a drain drain 10c formed on the side of the housing 10, and stored in a drain tank 100 as wastewater L1 containing the grinding chips D1.

[0019] In contrast to the above-described FIG. 1(a), FIG. 1(b) shows a cutting device 3 used to obtain cutting chips D2 generated by cutting work.

[0020] As shown in FIG. 1(b), the cutting device 3 has an approximately rectangular parallelepiped device housing 30, and is configured to include a chuck table 35 that holds the wafer 20, which is the workpiece, and cutting means 37 that has a cutting blade that cuts the wafer 20 held on the chuck table 35. The cutting device 3 includes a cassette 31 (shown by a two-dot chain line) for accommodating a plurality of wafers 20, a temporary storage table 32 for carrying out and temporarily storing the wafers 20 accommodated in the cassette 31, a carry-in / out means 33 for carrying out the wafers 20 to the temporary storage table 32, a transport means 34 for rotating and transporting the wafers 20 carried out to the temporary storage table 32 onto a chuck table 35, a cleaning means 39 for cleaning the wafers 20 cut by the cutting means 37, a cleaning and transport means 38 for transporting the cut wafers 20 from the chuck table 35 to the cleaning means 39, an imaging means 36 for imaging the wafers 20 on the chuck table 35, and a control means (not shown). When the wafers 20 are carried out of the cassette 31 by the carry-in / out means 33, the height of the cassette 31 is appropriately adjusted by an elevating means (not shown).

[0021] The apparatus housing 30 is provided with an X-axis feed means (not shown) for moving the chuck table 35 in the X-axis direction indicated by the arrow X, which is the cutting feed direction, a Y-axis feed means (not shown) for moving the cutting means 37 in the Y-axis direction indicated by the arrow Y, which is perpendicular to the X-axis direction, and a Z-axis feed means (not shown) for moving the cutting means 37 in the Z-axis direction indicated by the arrow Z, which is perpendicular to the X-axis and Y-axis directions. The cutting means 37 is also provided with a cutting water supply nozzle 372 for supplying pure water, that is, cutting water, to the cutting site when cutting the wafer 20 held by suction on the chuck table 35.

[0022] The cutting water supplied from the cutting supply nozzle 372 is supplied to the cutting position when cutting is performed, and then collected together with cutting chips D2 generated by the cutting process by a collection path (not shown) arranged in the cutting device 3, and discharged from the drainage drain 30a to the drainage tank 110, where it is stored as drainage water L2 mixed with the cutting chips D2.

[0023] In this embodiment, the wastewater L1 obtained by the grinding apparatus 1 or the wastewater L2 obtained by the cutting apparatus 3 is used to manufacture a wafer for inspection as described below.

[0024] Before carrying out the method for manufacturing a test wafer according to this embodiment, a wafer W serving as a base for the test wafer, as shown in FIG. 2, and a heating plate 40 are prepared. The wafer W is a circular plate-like object made of silicon (Si), the same material as the wafer 20 processed in the grinding apparatus 1 or cutting apparatus 3 described above. No devices are formed on the wafer W, and the front and back surfaces, which form flat surfaces, are referred to as a first surface Wa and a second surface Wb. The heating plate 40 has a flat surface 42, is configured to be rotatable by a rotary drive means (not shown), and is equipped with heating means such as an electric heater (not shown) inside, so that the surface 42 can be maintained at a constant temperature range (e.g., 80°C to 100°C).

[0025] In the inspection wafer manufacturing method of this embodiment, first, the wafer W is placed on the heating plate 40 with the first side Wa exposed and the second side Wb facing downward (heating plate placing step). At this time, an appropriate adhesive means is interposed between the second side Wb of the wafer W and the surface 42 of the heating plate 40 to ensure close contact. Once the wafer W is placed on the heating plate 40, the heating means of the heating plate 40 is activated to heat the surface 42 to the above temperature range, and a liquid supply means 44 (only a portion of which is shown) shown in FIG. 3 is positioned above the heating plate 40.

[0026] The liquid supply means 44 includes a swing arm 45 that can swing in the direction indicated by arrow R1 and a spray nozzle 46 formed at the tip of the swing arm 45. An ultrasonic vibration applying device (not shown) capable of applying a predetermined ultrasonic vibration V is provided on the swing arm 45 or the spray nozzle 46. A storage tank (not shown) is connected to the liquid supply means 44, and the storage tank stores wastewater L1 containing grinding chips D1 drained from the grinding device 1 or wastewater L2 containing cutting chips D2 drained from the cutting device 3. The wastewater L1 or wastewater L2 is pressurized and supplied by a pressure pump (not shown). It is preferable to provide agitation means for agitating the wastewater L1 or wastewater L2 so that the grinding chips D1 and cutting chips D2 contained in the wastewater L1 or wastewater L2 supplied to the liquid supply means 44 are uniformly distributed.

[0027] As described above, once the liquid supply means 44 is positioned above the heating plate 40, the pressure pump is operated, and as shown in Figure 3, the swing arm 45 is swung in the direction indicated by arrow R1 and the heating plate 40 is rotated in the direction indicated by arrow R2, while spraying the wastewater L1 or L2 from the spray port 47 of the spray nozzle 46 of the liquid supply means 44 onto the first surface Wa of the wafer W. At this time, since the ultrasonic applying device is operating, ultrasonic vibration V is applied to the wastewater L1 or L2 and it is sprayed onto the first surface Wa of the wafer W. Since the wafer W is heated to 80°C to 100°C by the heating plate 40, the moisture contained in the wastewater L1 or wastewater L2 supplied to the first surface Wa quickly evaporates, and as shown in the lower left of FIG. 3, the grinding debris D1 or cutting debris D2 contained in the wastewater L1 or wastewater L2 adheres to the first surface Wa of the wafer W as dust, forming a dust layer S on the first surface Wa of the wafer W (dust adhesion process). In the above-described embodiment, the wastewater L1 and wastewater L2 are exemplified as the liquid containing the grinding debris D1 and cutting debris D2 supplied to the liquid supply means 44, but the present invention is not limited thereto. For example, the grinding debris D1 and cutting debris D2 remaining as dust after removing the moisture from the wastewater L1 or wastewater L2 may be mixed with a liquid such as alcohol, stored in a storage tank, and supplied to the liquid supply means 44.

[0028] The wafer W manufactured by carrying out the heating plate placing step and the dust adhesion step and spraying the wastewater L1 becomes an inspection wafer W that replicates a wafer having grinding debris D1 attached to its surface and requiring cleaning, while the wafer W sprayed with the wastewater L2 becomes an inspection wafer W that replicates a wafer having cutting debris D2 attached to its surface and requiring cleaning. Furthermore, the dust constituting the dust layer S attached to the first surface Wa of this inspection wafer W is grinding debris D1 or cutting debris D2 obtained by grinding or cutting a silicon (Si) wafer 20, and is therefore of the same quality as the silicon inspection wafer W. Therefore, the inspection wafer W is closer to an actual wafer 20 that has been subjected to grinding or cutting processing, and by using such an inspection wafer W, it becomes possible to properly verify the cleaning effect of the cleaning function. In other words, it is possible to find conditions for high cleaning effectiveness by changing the flow rate and pressure of the cleaning water, the way it is mixed with gas, the rotation speed of the spinner table, the shape of the cleaning nozzle, the oscillation speed of the cleaning nozzle, etc., and to make an objective judgment by comparing the cleaning effectiveness with the cleaning functions of other companies' products.

[0029] Furthermore, grooves may be formed on the first surface Wa of the wafer W on which the dust adhesion step is performed. These grooves are provided, for example, on an inspection wafer W used to verify the cleaning effect of the cleaning means 19 of the cutting device 3. When manufacturing an inspection wafer W for verifying the cleaning effect of the cleaning means 19 of the cutting device 3, it is important that cutting grooves are formed on the actual wafer 20, and that cutting debris that gets into the cutting grooves is removed by the cleaning means 19. When verifying whether cutting debris that gets into such cutting grooves can be removed by the cleaning means 19, it is preferable to form grooves in a shape similar to the cutting grooves formed on the wafer 20.

[0030] As described above, when determining conditions for achieving a high cleaning effect or when comparing the cleaning effect with that of other companies' cleaning functions, it is preferable to prepare test wafers W with different amounts of dust accumulation. Test wafers W that meet such requirements will be described below.

[0031] FIG. 4 shows an inspection wafer W0 according to another embodiment of the present invention, which differs from the above-described embodiment. The inspection wafer W0 shown in FIG. 4 is based on a wafer made of silicon (Si), as in the above-described embodiment, and its surface (first surface) has multiple regions, for example, a first region Wa1, a second region Wa2, and a third region Wa3, which are divided into three equal parts with a central angle of 120 degrees. To obtain the inspection wafer W0 shown in FIG. 4, the first region Wa1 and the second region Wa2 are masked, and the above-described dust adhesion process is performed only on the third region Wa3. Next, only the first region Wa1 is masked, and the above-described dust adhesion process is performed on the second region Wa2 and the third region Wa3. Finally, the masks are all removed, and the above-described dust adhesion process is performed on the entire surface of the wafer W0. As a result, one dust layer S1 formed by one dust adhesion process is formed in the first region Wa1, two dust layers S2 formed by two dust adhesion processes are formed in the second region Wa2, and three dust layers S3 formed by three dust adhesion processes are formed in the third region Wa3. That is, the inspection wafer W0 shown in Fig. 4 has three regions with different amounts of dust accumulation, and by using one inspection wafer W0 to evaluate the cleaning function, the evaluation of the cleaning function can be performed in more detail.

[0032] Furthermore, with reference to FIG. 5, a case where two or more test wafers having different amounts of accumulated dust formed according to the present invention are prepared will be described.

[0033] 5 shows a test wafer set WS including a first test wafer W1, a second test wafer W2, and a third test wafer W3. The base wafers constituting each of the first test wafer W1, the second test wafer W2, and the third test wafer W3 are the same as the silicon wafer W described with reference to FIG. 2. The first test wafer W1 is obtained by performing the heating plate mounting step and the dust adhesion step once on the first surface Wa of the wafer W, thereby forming one dust layer S1. The second test wafer W2 is obtained by performing the heating plate mounting step and the dust adhesion step twice on the first surface Wa, thereby forming two dust layers S2. Furthermore, the third test wafer W3 was subjected to the heating plate mounting step and the above-mentioned dust adhesion step was performed three times on the first surface Wa, forming three dust layers S3. By preparing these as a set of test wafers and cleaning them using a predetermined cleaning means, it becomes possible to find conditions with high cleaning effectiveness by changing the flow rate and pressure of the cleaning water, the mixed form with gas, the rotation speed of the spinner table, the shape of the cleaning nozzle, and the oscillation speed of the cleaning nozzle, and to make an objective judgment by comparing the cleaning effect with the cleaning function of other companies' products. In addition, by using three test wafers with different amounts of dust accumulation and actually cleaning them by applying the cleaning function sequentially, and observing how the dust layer falls off, it becomes possible to evaluate the cleaning function in more detail.

[0034] Although the above-mentioned test wafer set WS includes three test wafers with different amounts of dust accumulation, it is not necessarily limited to being composed of three test wafers, and may be a set including two test wafers with different amounts of dust accumulation, or a set including four or more test wafers with different amounts of dust accumulation. Also, a plurality of test wafers with different amounts of dust accumulation may be prepared, and a required test wafer may be selected and used from the set of test wafers depending on the cleaning performance of the cleaning function to be evaluated.

[0035] In the above-described embodiment, the inspection wafer is formed from a silicon wafer, but the present invention is not limited to forming the inspection wafer from silicon. The inspection wafer of the present invention is preferably formed from a wafer made of the same material as the wafer processed by the grinding device 1 and the cutting device 3. For example, if the wafer processed by the grinding device 1 and the cutting device 3 is a silicon carbide (SiC) wafer or a sapphire wafer, the inspection wafer may also be manufactured from a silicon carbide (SiC) wafer or a sapphire wafer depending on the material of the workpiece. [Explanation of symbols]

[0036] 1: Grinding device 10: Device housing 10a: Support wall 10b: Drain port 10c: Wastewater drain 11: First transport means 12a: First cassette 12b: Second cassette 13:Temporary storage means 14: Second transport means 15: Chuck table 16: Grinding means 162: Grinding wheel 17: Grinding feed mechanism 18:Third transportation means 19: Cleaning method 3:Cutting device 30: Device housing 31: Cassette 32: Temporary table 33: Carrying in / out means 34: Means of transport 35: Chuck table 36: Imaging means 37: Cutting means 38: Cleaning and transport means 39: Cleaning method 20: Wafer 40: Heating plate 42: Surface 44:Liquid supply means 45: Swing arm 46: Injection nozzle 47: Nozzle 100, 110: Drainage tank D1: Grinding chips D2: Cutting waste L1, L2: Drainage W, W0: wafer for inspection W1: First test wafer W2: Second test wafer W3: Third test wafer Wa: First side Wb: Second Side Wa1: First area Wa2:Second area Wa3: Third area WS: Set of wafers for inspection S: Dust layer S1: One dust layer S2: Two dust layers S3: Three dust layers

Claims

1. Used to evaluate the cleaning effect of the cleaning function of a cleaning means disposed in a grinding machine, An inspection wafer having a first surface and a second surface, with dust attached to at least the first surface, The dust is a test wafer that is grinding chips discharged when a grinding process is carried out by a grinding device that grinds wafers of the same quality as the dust.

2. Used to evaluate the cleaning effect of the cleaning function of the cleaning means disposed in the cutting device, An inspection wafer having a first surface and a second surface, with dust attached to at least the first surface, The dust is a test wafer that is chips discharged when cutting is performed by a cutting device that cuts a wafer of the same quality as the dust.

3. An inspection wafer as described in claim 1 or 2, wherein a plurality of areas having different amounts of dust accumulation are formed on the first surface.

4. An inspection wafer as described in any one of claims 1 to 3, wherein a groove is formed on the first surface.

5. A method for manufacturing an inspection wafer used to evaluate the cleaning effect of a cleaning function of a cleaning means disposed in a grinding device or a cutting device, comprising: a heating plate placing step of placing the second surface of the wafer on a heating plate with the first surface exposed; a dust adhering step of spraying a liquid containing dust onto the first surface to cause the dust to adhere to the first surface, and then heating the wafer with the heating plate to form a dust layer; wherein the dust is grinding chips discharged when a grinding process is performed using a grinding device that grinds wafers of the same quality as the dust, or cutting chips discharged when a cutting process is performed using a cutting device that cuts wafers of the same quality as the dust.

6. A method for manufacturing an inspection wafer as described in Claim 5, wherein the formation of the dust layer is carried out multiple times in the dust adhesion process.

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