Wafer processing methods

Abstract

[Problem] To provide a wafer processing method that enables each component wafer to inherit past information and ensures the traceability of each component wafer. [Solution] The wafer processing method includes: a dicing apparatus preparation step; an information registration step, which registers the information to be marked in the control means of the dicing apparatus; a holding step, which holds the front side of the wafer 38 on the chuck stage 4 of the dicing apparatus and exposes the back side 38b side of the wafer 38, the wafer 38 having a front side divided by a plurality of components 42 by a predetermined dicing line 40; a position registration step, which uses the imaging means 8 of the dicing apparatus to photograph the wafer 38 held on the chuck stage 4, and specifies the position of each component 42 to be marked in X and Y coordinates and registers it in the control means; and a marking step, which, based on the X and Y coordinates registered in the position registration step, marks the information registered in the information registration step on the back side of each component 42 with a dicing blade 22.

Description

Technical Field

[0001] This invention relates to a method for processing wafers. Prior Technology

[0002] A wafer with multiple components such as ICs and LSIs formed on the front side by dividing lines is formed to the desired thickness by grinding the back side with a grinding machine, and then divided into individual component chips by a dicing machine. The divided component chips are used in electronic devices such as mobile phones and personal computers.

[0003] At the desired location on the wafer (e.g., the remaining area on the periphery adjacent to the orientation flat), markings include text or ID marks containing barcodes, product numbers, product names, batch numbers, etc., for managing the wafer. The ID marks are identified in each manufacturing step to perform the desired processing on the wafer, and past information is inherited to ensure traceability (e.g., see Patent Document 1). [Known Technical Documents] [Patent Literature]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-330196 Summary of the Invention

[0005] [The problem that the invention aims to solve] However, if a wafer is divided into individual component chips, each component chip will have the problem of not being able to inherit past information and becoming untraceable.

[0006] In view of the above facts, the objective of the present invention is to provide a wafer processing method that enables each component chip to inherit past information and ensures the traceability of each component chip.

[0007] [Technical means to solve the problem] According to the present invention, a wafer processing method is provided to solve the above-mentioned problems. Specifically, a wafer processing method is provided, comprising: a dicing apparatus preparation step, wherein the dicing apparatus includes at least: a chuck stage that holds the wafer and is rotatable; a dicing means rotatably equipped with a dicing blade for cutting the wafer held on the chuck stage; an X-axis feed means that performs processing feed of the chuck stage and the dicing means relative to each other in the X-axis direction; a Y-axis feed means that performs indexing feed of the chuck stage and the dicing means relative to each other in the Y-axis direction orthogonal to the X-axis direction; a Z-axis feed means that performs cutting feed of the chuck stage and the dicing means relative to each other in the Z-axis direction orthogonal to both the X-axis and Y-axis directions; an imaging means that captures images of the wafer held on the chuck stage; and a display means that displays the images captured by the imaging means. The image; and control means; an information registration step, which registers the information to be marked in the control means; a holding step, which holds the front side of the wafer on the chuck stage and exposes the back side of the wafer, the wafer having a front side divided by multiple elements by predetermined dicing lines; a position registration step, which uses the camera means to photograph the wafer held on the chuck stage, specifies the position of each element to be marked in X and Y coordinates and registers it in the control means; and a marking step, which, based on the X and Y coordinates registered in the position registration step, actuates the X-axis feed means and the Y-axis feed means to position the dicing blade at the desired position, and actuates the Z-axis feed means to mark the information registered in the information registration step on the back side of each element with the dicing blade.

[0008] Preferably, the marking step is performed before the wafer is diced into individual component wafers. It is desirable to perform a front-side protective member placement step, in which a protective member is placed on the front side of the wafer, before the holding step.

[0009] Preferably, the method includes: a wafer support step in which a dicing film is adhered to the back side of the wafer and the wafer is supported by a frame having an opening for accommodating the wafer and through the dicing film; and a dicing step in which the protective member is peeled off from the front side of the wafer to divide the wafer into individual component chips.

[0010] Preferably, the marking step is performed after the wafer has been diced into individual component wafers. Preferably, before the holding step, a holding member placement step is included, wherein a holding member for maintaining the wafer shape is placed on the front side of the wafer that has been diced into individual component wafers.

[0011] [Invention Benefits] The wafer processing method of the present invention includes the following steps, thus enabling each component wafer to inherit past information and ensuring the traceability of each component wafer: a dicing apparatus preparation step, which prepares a dicing apparatus, the dicing apparatus comprising at least: a chuck stage that holds the wafer and is rotatable; a dicing means rotatably equipped with a dicing blade for cutting the wafer held on the chuck stage; an X-axis feed means that performs processing feed of the chuck stage and the dicing means relative to each other in the X-axis direction; a Y-axis feed means that performs indexing feed of the chuck stage and the dicing means relative to each other in the Y-axis direction orthogonal to the X-axis direction; a Z-axis feed means that performs cutting feed of the chuck stage and the dicing means relative to each other in the Z-axis direction orthogonal to the X-axis and the Y-axis directions; an imaging means that captures images of the wafer held on the chuck stage; and a display. The device includes: a means for displaying an image captured by the camera; a control means; an information registration step for registering the information to be marked in the control means; a holding step for holding the front side of the wafer on the chuck stage and exposing the back side of the wafer, the wafer having a front side divided by multiple elements with predetermined dicing lines; a position registration step for capturing an image of the wafer held on the chuck stage with the camera, specifying the position of each element to be marked in X and Y coordinates and registering it in the control means; and a marking step for actuating the X-axis feed means and the Y-axis feed means based on the X and Y coordinates registered in the position registration step, positioning the dicing blade in the desired position, and actuating the Z-axis feed means to mark the information registered in the information registration step on the back side of each element with the dicing blade. Simple Explanation of the Diagram

[0012] Figure 1 is a perspective view of the cutting device. Figure 2 is a perspective view showing the status of the front protective component installation process. Figure 3(a) is a perspective view showing the state in which the wafer has been positioned above the chuck stage, and Figure 3(b) is a perspective view showing the state in which the wafer is held by the chuck stage. Figure 4 is a three-dimensional view showing the status of the location registration process in progress. Figure 5(a) is a perspective view showing the state of the marking process in progress, and Figure 5(b) is a partial top view of the back side of the marked wafer. Figure 6 is a perspective view showing the state of the wafer support process underway. Figure 7 is a three-dimensional view showing the state of the segmentation process in progress. Figure 8 is a three-dimensional view of a wafer that has been divided into component chips. Implementation

[0013] Hereinafter, a preferred embodiment of the wafer processing method of the present invention will be described with reference to the accompanying drawings.

[0014] (Preparation steps for the cutting device) In the illustrated embodiment, the first step is to prepare the necessary cutting device. For example, the cutting device 2 shown in Figure 1 can be prepared in this step.

[0015] The dicing apparatus 2 includes at least: a chuck stage 4 that holds and rotates the wafer; a dicing blade 6 rotatably equipped with a dicing blade for cutting the wafer held in the chuck stage 4; an X-axis feed means (not shown) that feeds the chuck stage 4 and the dicing blade 6 relative to each other in the X-axis direction; a Y-axis feed means (not shown) that indexes the chuck stage 4 and the dicing blade 6 relative to each other in the Y-axis direction, which is orthogonal to the X-axis direction; a Z-axis feed means (not shown) that cuts the chuck stage 4 and the dicing blade 6 relative to each other in the Z-axis direction, which is orthogonal to both the X-axis and Y-axis directions; an imaging means 8 that captures images of the wafer held in the chuck stage 4; a display means 10 that displays the images captured by the imaging means 8; and a control means 12. Furthermore, the X, Y, and Z axes are the directions indicated by arrows X, Y, and Z in Figure 1, respectively. The XY plane defined by the X-axis and Y-axis directions is substantially horizontal, and the Z-axis direction is vertical.

[0016] The chuck stage 4 is configured to move freely in the X-axis direction and rotate freely about the Z-axis. A porous, circular suction chuck 14, connected to a suction means (not shown), is disposed at the upper end of the chuck stage 4. The chuck stage 4 attracts and holds the wafer placed on the upper surface of the suction chuck 14 by generating an attractive force on the upper surface of the suction chuck 14 using the suction means. Furthermore, a plurality of clamps 16 are arranged at circumferential intervals around the periphery of the chuck stage 4.

[0017] Referring to Figures 1 and 5, the cutting means 6 includes: a spindle housing 18 (see Figure 5) configured to be movable in both the Y-axis and Z-axis directions; a spindle 20 rotatably supported by the spindle housing 18; an annular cutting blade 22 fixed to the front end of the spindle 20; and a motor (not shown) that rotates the spindle 20.

[0018] The X-axis feed means includes: a ball screw connected to the chuck table 4 and extending in the X-axis direction; and a motor that rotates the ball screw. Moreover, the X-axis feed means converts the rotational motion of the motor into linear motion via the ball screw and transmits it to the chuck table 4, thereby feeding the chuck table 4 in the X-axis direction relative to the cutting means 6.

[0019] The Y-axis feed means includes: a ball screw connected to the spindle housing 18 of the cutting means 6 and extending in the Y-axis direction; and a motor that rotates the ball screw. The Y-axis feed means converts the rotational motion of the motor into linear motion via the ball screw and transmits it to the spindle housing 18, indexing and feeding the cutting means 6 in the Y-axis direction relative to the chuck table 4.

[0020] The Z-axis feed means includes: a ball screw connected to the spindle housing 18 and extending in the Z-axis direction; and a motor that rotates the ball screw. In the Z-axis feed means, the rotational motion of the motor is converted into linear motion by the ball screw and transmitted to the spindle housing 18, so that the cutting means 6 is fed in the Z-axis direction relative to the chuck table 4.

[0021] The imaging means 8 is positioned above the track of the chuck stage 4. The imaging means 8 includes: a general photographic element (CCD) that photographs the wafer using visible light; an infrared irradiation means that irradiates the wafer with infrared light; an optical system that captures the infrared light irradiated by the infrared irradiation means; and a photographic element (infrared CCD) that outputs an electronic signal corresponding to the infrared light captured by the optical system (all not shown). The image captured by the imaging means 8 is sent to the display means 10 and the control means 12.

[0022] The control means 12 is composed of a computer, which has: a central processing unit (CPU) that performs calculations according to a control program; a read-only memory (ROM) that stores the control program, etc.; and a random access memory (RAM) that stores the calculation results, etc. and can be read and written.

[0023] The dicing apparatus 2 further includes: a cassette stage 26 that can be raised and lowered, which holds and accommodates cassettes 24 containing multiple wafers; a transfer means 30 that pulls out the wafers before processing from the cassettes 24 and transfers them to a temporary stage 28, and transfers the processed wafers already positioned on the temporary stage 28 into the cassettes 24; a first transfer means 32 that transfers the wafers before processing that have been transferred from the cassettes 24 to the temporary stage 28 to the chuck stage 4; a cleaning means 34 that cleans the processed wafers; and a second transfer means 36 that transfers the processed wafers from the chuck stage 4 to the cleaning means 34.

[0024] (Information Login Steps) After the dicing apparatus preparation step is performed, an information registration step is performed to register the information to be marked in the control means 12. The information to be marked is used to identify each of the multiple components formed on the wafer.

[0025] (Steps for installing front protective components) In the illustrated embodiment, after the information registration step, a front protective component installation step is performed to install a protective component on the front side of the wafer.

[0026] Figure 2 shows a wafer 38 that can be processed by the wafer processing method of this embodiment. The wafer 38 is in the shape of a circular plate and can be formed, for example, from a suitable semiconductor material such as silicon. The front side 38a of the wafer 38 is divided into multiple rectangular regions by grid-like dividing lines 40, and IC, LSI, and other components 42 are formed in each of the multiple rectangular regions. Furthermore, a notch 44 indicating the crystal orientation is formed at the periphery of the wafer 38.

[0027] In the front protective member placement step, as shown in Figure 2, a circular protective member 46 is placed on the front side 38a of the wafer 38. The circular protective member 46 has a diameter almost identical to that of the wafer 38. The protective member 46 may have an adhesive layer; in this case, this step can be performed by attaching the protective member 46 to the front side 38a of the wafer 38. Furthermore, if a thermosetting sheet, such as a polyolefin sheet, is used as the protective member 46, an adhesive layer is not required.

[0028] (Keep the steps) After the front protective component installation step is performed, a holding step is performed, which holds the front 38a side of the wafer 38 on the chuck stage 4 and exposes the back 38b side of the wafer 38, the wafer 38 having a front 38a with a plurality of elements 42 divided by a predetermined dividing line 40.

[0029] As shown in Figure 3, in the holding step, firstly, the wafer 38 is placed on the upper surface of the chuck stage 4 with the front side 38a facing down. Next, the attraction means connected to the adsorption chuck 14 is activated to generate an attraction force on the upper surface of the adsorption chuck 14, thereby attracting and holding the wafer 38 with the upper surface of the adsorption chuck 14.

[0030] (Location login steps) After the holding step is performed, a position registration step is performed, which involves using a camera 8 to photograph the wafer 38 held on the chuck stage 4, specifying the position of each element 42 to be marked using X and Y coordinates, and registering it with the control means 12.

[0031] In the location registration step, firstly, the chuck stage 4 is moved by the X-axis feed means to position the wafer 38 below the imaging means 8. Next, the imaging means 8 captures an image of the wafer 38 held on the chuck stage 4. Then, based on the image of the wafer 38 captured by the imaging means 8, the dicing predetermined line 40 is aligned with the X-axis direction.

[0032] At this time, although the back side 38b of the wafer 38 faces upward and the front side 38a with the pre-defined dividing line 40 is facing downward, as mentioned above, the imaging means 8 includes an infrared illumination means, an optical system capable of capturing infrared light, and an imaging element (infrared CCD) that outputs electronic signals corresponding to infrared light. Therefore, it can penetrate the back side 38b of the wafer 38 and capture the pre-defined dividing line 40 of the front side 38a.

[0033] Next, the position of each element 42 to be marked is specified using X and Y coordinates. For example, as shown in FIG4, the position of element 42 can be specified by detecting the X and Y coordinates of the intersection points of the center lines L of the dividing predetermined lines 40. Specifically, the position of element 42a to be marked can be specified by detecting the coordinates of the four intersection points around element 42a: (X3, Y3), (X3, Y4), (X4, Y3), and (X4, Y4). This process is repeated to specify the position of all elements 42 using X and Y coordinates.

[0034] Furthermore, during the location registration step, the X and Y coordinates of the characteristic pattern (key pattern) on the detection element 42 can be used instead of the intersection coordinates around the detection element 42 to determine the location of the element 42. In addition, the origin of the X and Y coordinates can be arbitrarily set. For example, the origin of the X and Y coordinates can be set at the notch 44.

[0035] (Marking steps) After the location registration step, a marking step is performed. The marking step is based on the X and Y coordinates registered in the location registration step. The X-axis feed means and the Y-axis feed means are activated to position the cutting blade 22 at the desired position. The Z-axis feed means is activated to mark the information registered in the information registration step on the back of each component 42 with the cutting blade 22.

[0036] In the marking step, firstly, the chuck stage 4 is moved by the X-axis feed means to position the wafer 38 below the dicing means 6. Next, based on the X and Y coordinates registered in the position registration step, the X-axis feed means and the Y-axis feed means are activated to position the dicing blade 22 above the element 42 to be marked.

[0037] Next, the spindle housing 18 is lowered by the Z-axis feed mechanism, causing the cutting edge of the high-speed rotating cutting blade 22 to cut into the back side 38b of the wafer 38 to a point before reaching the front side 38a, and cutting water is supplied to the portion where the cutting edge of the cutting blade 22 cuts in. Then, as shown in FIG5, while the X, Y, and Z-axis feed mechanisms are operated appropriately, the cutting edge of the cutting blade 22 is repeatedly cut into the back side 38b of the wafer 38, and a mark 48 that can be formed in the form of a barcode is formed on the back side of the component 42.

[0038] If a mark 48 has already been formed on one element 42, the mark 48 is repeated while the chuck stage 4 is moved only by the amount of the X-axis interval of the predetermined dividing line 40 in the X-axis direction. Furthermore, after all elements 42 in a row have been marked with marks 48, the chuck stage 4 is moved only by the amount of the Y-axis interval of the predetermined dividing line 40 in the Y-axis direction, and marks 48 are formed on the next row of elements 42. This process is repeated until all elements 42 on the wafer 38 are marked with marks 48.

[0039] (Wafer support steps) In the illustrated embodiment, after the marking step, as shown in Figure 6, a wafer support step is performed. This wafer support step involves attaching a dicing film 50 to the back surface 38b of the wafer 38, and supporting the wafer 38 through a frame 52 having an opening 52a to accommodate the wafer 38 and through the dicing film 50. Furthermore, the wafer support step is performed after the wafer 38 is removed from the chuck table 4 by releasing its attractive force.

[0040] (Segmentation steps) After the wafer support step, a dicing step is performed, in which the protective member 46 is peeled off from the front side 38a of the wafer 38 to divide the wafer 38 into individual component wafers.

[0041] In the dicing step, firstly, as shown in FIG. 6, the protective member 46 is peeled off from the front side 38a of the wafer 38. Next, with the front side 38a of the wafer 38 facing upward, the wafer 38 is held by the upper surface of the chuck stage 4. Furthermore, the frame 52 is fixed by the clamp 16 of the chuck stage 4. Next, the wafer 38 is photographed by the imaging means 8. Based on the image of the wafer 38 photographed by the imaging means 8, the dicing predetermined line 40 is aligned with the X-axis direction, and the area corresponding to the dicing predetermined line 40 aligned with the X-axis direction is positioned below the dicing blade 22.

[0042] Next, as shown in Figure 7, the cutting edge of the high-speed rotating cutting blade 22 cuts into the front side 38a until it reaches the back side 38b. While supplying cutting water to the part where the cutting edge of the cutting blade 22 cuts in, the chuck table 4 (omitted in Figure 7) is fed in the X-axis direction relative to the cutting means 6, thereby forming a dividing groove 54 along the predetermined dividing line 40.

[0043] Then, relative to the chuck stage 4, while feeding the cutting blade 22 in the Y-axis direction only at intervals along the Y-axis of the predetermined dividing lines 40, the dividing grooves 54 are repeatedly formed, and the dividing grooves 54 are formed along all the predetermined dividing lines 40 that are already aligned with the X-axis direction. Furthermore, after rotating the chuck stage 4 90 degrees, the dividing grooves 54 are repeatedly formed while feeding in an indexing manner, and the dividing grooves 54 are formed along all the predetermined dividing lines 40 that are orthogonal to the previously formed dividing lines 40. This process is repeated, as shown in FIG. 8, to divide the wafer 38 into individual component wafers.

[0044] As described above, in the illustrated embodiment, because a mark 48 is formed on each element 42 by cutting, each element chip can inherit past information and ensure the traceability of each element chip.

[0045] Furthermore, although the illustrated embodiment illustrates an example of performing a marking step before dividing the wafer 38 into individual component wafers, the marking step can also be performed after dividing the wafer 38 into individual component wafers.

[0046] In cases where a marking step is performed after dicing, it is preferable to perform a wafer support step and a dicing step, followed by a step of placing a maintaining member (e.g., a circular adhesive film similar to the protective member 46) on the front side 38a of the wafer 38 that has been diced into individual component chips. After peeling the wafer 38 from the cutting adhesive film 50, a holding step, a position registration step, and a marking step are performed.

[0047] 2: Cutting device 4: Chuck platform 6: Cutting methods 8: Camera techniques 10: Display methods 12: Control methods 22: Cutting blade 38: Wafer 38a: Front side of the wafer 38b: Back side of the wafer 40: Pre-defined dividing line 42: Components 46: Protective components 48: Mark 50: Cutting the adhesive film 52: Framework 52a: Opening of the frame

Claims

1. A wafer processing method, comprising: a dicing apparatus preparation step, wherein the dicing apparatus includes at least: a chuck stage for holding and rotating the wafer; a dicing means rotatably equipped with a dicing blade for cutting the wafer held on the chuck stage; an X-axis feed means for feeding the chuck stage and the dicing means relative to each other in an X-axis direction; a Y-axis feed means for indexing the chuck stage and the dicing means relative to each other in a Y-axis direction orthogonal to the X-axis direction; a Z-axis feed means for cutting the chuck stage and the dicing means relative to each other in a Z-axis direction orthogonal to both the X-axis and Y-axis directions; an imaging means for capturing images of the wafer held on the chuck stage; a display means for displaying images captured by the imaging means; and a control means; and an information registration step, wherein information to be marked is registered in the control means. The process includes a holding step, which holds the front side of the wafer on the chuck stage and exposes the back side of the wafer, the wafer having a front side divided by multiple components with predetermined dicing lines; a position registration step, which uses the camera to photograph the wafer held on the chuck stage, identifies the position of each component to be marked using X and Y coordinates, and registers it with the control means; and a marking step, which, based on the X and Y coordinates registered in the position registration step, actuates the X-axis feed means and the Y-axis feed means to position the dicing blade at the desired position, and actuates the Z-axis feed means to mark the information registered in the information registration step on the back side of each component with the dicing blade.

2. The wafer processing method as described in Request 1, wherein, This marking step is performed before the wafer is diced into individual component wafers.

3. The wafer processing method as described in Request 1, wherein, Prior to the holding step, a front protective member placement step is performed on the front side of the wafer.

4. The wafer processing method as described in Request 3, wherein, The wafer includes: a wafer support step in which a dicing film is adhered to the back side of the wafer and the wafer is supported by a frame having an opening for accommodating the wafer and through the dicing film; and a dicing step in which the protective member is peeled off from the front side of the wafer to divide the wafer into individual component wafers.

5. The wafer processing method as described in Request 1, wherein, This marking step is performed after the wafer is diced into individual component wafers.

6. The wafer processing method as described in Request 5, wherein, Prior to the holding step, there is a holding member placement step, which involves placing a holding member on the front side of the wafer, which has been divided into individual element wafers, to maintain the shape of the wafer.

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