JP7472368B2 - Substrate Processing Equipment - Google Patents

Description

The present invention relates to a substrate processing device that processes non-circular substrates into flat surfaces.

In the field of semiconductor manufacturing, substrate processing devices are known that process semiconductor substrates (hereafter referred to as "substrates") such as silicon wafers into thin, flat surfaces.

Patent Document 1 discloses a grinding device that brings a rotating grinding wheel into contact with the top surface of a rectangular workpiece held on a chuck table, grinding the rectangular workpiece to a specified thickness.

Patent No. 5230982

However, when grinding is performed by contacting a grinding wheel parallel to a rectangular workpiece held on a chuck table, the contact area between the grinding wheel and the rectangular workpiece for each given rotation of the chuck table is not constant, and in areas where the contact area is relatively large, the amount of the rectangular workpiece ground tends to be small, while in areas where the contact area is relatively small, the amount of the rectangular workpiece ground tends to be large. In other words, there is a problem that the thickness of the rectangular workpiece varies depending on the size of the contact area between the grinding wheel and the rectangular workpiece during processing, making it impossible to finish the rectangular workpiece to the desired thickness.

Therefore, a technical problem arises that must be solved in order to flatten a non-circular substrate to the desired thickness, and the present invention aims to solve this problem.

In order to achieve the above object, the substrate processing device according to the present invention is a substrate processing device that uses a grindstone to planarize a non-circular substrate held by suction on a chuck table, the chuck table being formed according to the shape of the substrate and including an adsorption body capable of adsorbing and holding the substrate, and a dense body having the adsorption body embedded in the center, and on the outer periphery of the dense body, a notch is formed that expands and contracts the contact area with the grindstone for each predetermined rotation angle of the chuck table in response to changes in the expected contact area between the substrate and the grindstone when the substrate is processed by the grindstone during self-grinding in which the grindstone grinds the holding surface of the chuck table.

According to this configuration, the dense body is formed so that the amount of grinding by the self-grinding of the grinding wheel, which grinds the holding surface, increases and decreases for each specified rotation angle of the chuck table, so as to offset the variation in thickness of the processed substrate caused by the change in the expected contact area between the substrate and the grinding wheel for each specified rotation angle of the chuck table when the substrate is processed by the grinding wheel. This reduces the variation in thickness of the processed substrate caused by the shape of the substrate.

In the present invention, the dense body is formed so that the amount of self-grinding in which the grinding wheel grinds the holding surface increases and decreases for each specified rotation angle of the chuck table, so that thickness variations caused by local changes in the amount of grinding of non-circular substrates can be offset, thereby reducing thickness variations in the processed substrate due to the shape of the substrate.

1 is a schematic diagram showing a substrate processing apparatus according to an embodiment of the present invention; Schematic diagram showing self-grinding. 11 is a plan view comparing the predicted contact areas between the substrate and the grindstone at two points in the substrate. FIG. FIG.

The embodiment of the present invention will be described with reference to the drawings. Note that in the following, when referring to the number, numerical value, amount, range, etc. of components, unless otherwise specified or when it is clearly limited to a specific number in principle, it is not limited to that specific number, and it may be more or less than the specific number.

In addition, when referring to the shape or positional relationship of components, etc., this includes things that are substantially similar or approximate to that shape, etc., unless otherwise specified or considered in principle to be otherwise.

In addition, drawings may exaggerate characteristic parts to make the features easier to understand, and the dimensional ratios of components may not necessarily be the same as in reality.

Figure 1 is a front view showing the basic configuration of a substrate processing device 1. The substrate processing device 1 performs grinding processing on a wafer. The substrate processing device 1 is equipped with a holding means 2 and a processing means 3.

The holding means 2 includes a chuck table 21 and a chuck spindle 22.

The chuck table 21 has an adsorbent 23 made of a porous material such as alumina on its upper surface, and a dense body 24 in which the adsorbent 23 is embedded approximately in the center. The chuck table 21 has a pipeline (not shown) that runs through the inside and reaches the surface. The pipeline is connected to a vacuum source, a compressed air source, or a water supply source via a rotary joint (not shown). When the vacuum source is activated, the substrate W placed on the adsorbent 23 is adsorbed and held by the adsorbent 23. When the compressed air source or water supply source is activated, the adsorption between the substrate W and the adsorbent 23 is released.

The adsorption body 23 is formed in a shape corresponding to the substrate W when viewed from above. In addition, the dense body 24 is formed in a substantially circular shape with a portion of the outer periphery cut out when viewed from above, but the shape of the dense body 24 is not limited to this. The detailed shape of the dense body 24 will be described later.

The chuck spindle 22 is configured to rotate the chuck table 21 around the rotation axis 2a. The drive source for the chuck spindle 22 may be, for example, a servo motor.

The holding means 2 further includes a rotation angle detection unit 25. The rotation angle detection unit 25 detects the rotation angle of the chuck table 21 and sends a detection signal to the control device 4 described below each time the chuck table 21 rotates a predetermined angle. For example, when the chuck spindle 22 is rotated by a servo motor, the rotation angle detection unit 25 can detect the rotation angle of the chuck table 21 by reading the rotation angle of the servo motor, since the rotation angle of the chuck table 21 corresponds to the rotation angle of the servo motor.

The processing means 3 includes a grinding wheel 31, a grinding wheel spindle 32, and an in-feed mechanism 33.

The grinding wheel 31 is, for example, a cup-shaped grinding wheel, and is attached to the lower end of the grinding wheel spindle 32.

The grindstone spindle 32 is rotatable around the rotation axis 3a, and the grindstone 31 and the grindstone spindle 32 are configured to rotate together.

The in-feed mechanism 33 raises and lowers the grinding wheel spindle 32 in the vertical direction. The in-feed mechanism 33 is of a known configuration, and is composed of, for example, multiple linear guides that guide the movement direction of the grinding wheel spindle 32, and a ball screw slider mechanism that raises and lowers the grinding wheel spindle 32. The in-feed mechanism 33 is interposed between the grinding wheel spindle 32 and the column 34.

The operation of the substrate processing apparatus 1 is controlled by the control device 4. The control device 4 controls each of the components that make up the substrate processing apparatus 1. The control device 4 is composed of, for example, a CPU, a memory, etc. The functions of the control device 4 may be realized by controlling it using software, or may be realized by operating it using hardware.

Next, the self-grinding of the substrate processing device 1 will be explained with reference to FIG. 2. FIG. 2 is a schematic diagram showing the self-grinding process.

As shown in FIG. 2, self-grinding refers to a process in which the grindstone 31 is brought close to the chuck table 21 by the in-feed mechanism 33, and the grindstone 31 grinds the holding surface 21a of the chuck table 21. Self-grinding is performed as necessary to maintain the holding surface 21a of the chuck table 21 in a desired shape, and is generally performed when the chuck table 21 is replaced, etc.

In the substrate processing device 1, the amount of grinding during self-grinding is locally increased or decreased within the holding surface 21a. This is because when the processing surface of the grindstone 31 is brought into parallel contact with the non-circular processed surface of the substrate W to perform flat processing of the substrate W, the amount of processing (grinding amount) of the substrate W is not stable within the surface.

The reasons for this will be explained below with reference to Figures 3 and 4. Figure 3 is a plan view comparing the expected contact areas between the substrate W and the grindstone 31 at two points within the substrate W. Figure 4 is a plan view showing the chuck table 21. Note that the following will be explained using as an example a substrate W that is square in plan view, but the shape of the substrate W is not limited to this.

As shown in FIG. 3, when comparing the predicted contact area S1 between the grinding wheel 31 and the substrate W (rotation angle of the chuck table 21 = Θ) where the processing surface of the grinding wheel 31 is set to pass through the corners of the substrate W and the rotation center O of the chuck table 21, with the predicted contact area S2 between the grinding wheel 31 and the substrate W (rotation angle of the chuck table 21 = Θ - 45 degrees) where the processing surface of the grinding wheel 31 is set to pass through the center of the side of the substrate W and the rotation center O, it can be seen that the predicted contact area S1 is approximately twice as large as the predicted contact area S2.

When the grinding wheel 31 is brought into uniform contact with the entire surface of the substrate W, as the predicted contact area between the substrate W and the grinding wheel 31 increases, the amount of substrate W ground decreases, and the substrate W becomes thicker after processing. Therefore, when comparing the predicted contact areas S1 and S2 shown in Figure 3, it is predicted that the substrate W will become locally thicker after processing when the predicted contact area S1 is used.

Therefore, as shown in FIG. 4, the dense body 24 is formed in a generally circular disk shape with a portion of the outer periphery cut out, and is configured so that the contact area with the grinding wheel 31 changes appropriately along the rotation direction of the chuck table 21.

Specifically, a notch 26 is provided on the outer periphery of the dense body 24 so that the contact area between the chuck table 21 and the grindstone 31 is inversely proportional to the expected contact area between the substrate W and the grindstone 31 when the substrate W is flattened by the grindstone 31.

In other words, if the predicted contact area between the substrate W and grindstone 31 within a specified rotation angle of the chuck table 21 is larger than the reference predicted contact area (reference area) between the substrate W and grindstone 31, the area of the cutout 26 is set so that the contact area between the chuck table 21 and grindstone 31 within this rotation angle is reduced. Note that the interval of the rotation angle of the chuck table 21 for calculating the predicted contact area can be changed as desired.

In addition, if the expected contact area between the substrate W and the grinding wheel 31 at a given rotation angle of the chuck table 21 is smaller than the reference area, the area of the cutout portion 26 is set so that the contact area between the chuck table 21 and the grinding wheel 31 within this rotation angle is increased.

In this way, the contact area between the chuck table 21 and the grinding wheel 31 is expanded or contracted inversely proportional to the expected contact area between the substrate W and the grinding wheel 31 based on the reference area.

Figure 4 shows the shape of the dense body 24 when the expected contact area S2 shown in Figure 3 is set as the reference area. That is, as the chuck table 21 rotates from (Θ-45 degrees) to Θ, the expected contact area between the substrate W and grinding wheel 31 increases, and the area of the cutout portion 26 also gradually increases. As a result, the contact area between the chuck table 21 and grinding wheel 31 during self-grinding gradually decreases in inverse proportion to the increase in the expected contact area between the substrate W and grinding wheel 31.

In this way, in the substrate processing apparatus 1 according to this embodiment, the dense body 24 is formed so that the amount of grinding by the self-grinding of the grinding wheel 31 grinding the holding surface 21a increases or decreases for each predetermined rotation angle of the chuck table 21, so as to offset the variation in thickness of the substrate W caused by the change in the expected contact area where the substrate W comes into contact with the grinding wheel 31 for each predetermined rotation angle of the chuck table 21 when the substrate W is processed by the grinding wheel 31. This reduces the variation in thickness of the substrate W after processing caused by the shape of the substrate W.

Furthermore, the present invention can be modified in various ways other than those described above without departing from the spirit of the present invention, and it goes without saying that the present invention extends to such modifications. Furthermore, the above-mentioned embodiments and modifications may be combined with each other.

1 ... Substrate processing device 2 ... Holding means 21 ... Chuck table 22 ... Chuck spindle 23 ... Adsorption body 24 ... Dense body 25 ... Rotation angle detection unit 26 ... Notch portion 3 ... Processing means 31 ... Grindstone 32 ... Grindstone spindle 33 ... In-feed mechanism 34 ... Column 4 ... Control device (control means)
O: Center of rotation (of the chuck table) W: Substrate

Claims (1)

A substrate processing apparatus that uses a grindstone to flatten a non-circular substrate that is held by suction on a chuck table,
The chuck table is
an adsorption body formed in accordance with the shape of the substrate and capable of adsorbing and holding the substrate;
A dense body having the adsorbent embedded in the center;
Equipped with
A substrate processing apparatus characterized in that a notch is formed on the outer periphery of the dense body during self-grinding in which the grinding wheel grinds the holding surface of the chuck table, such that the contact area with the grinding wheel expands and contracts for each specified rotation angle of the chuck table in response to changes in the predicted contact area between the substrate and the grinding wheel when the substrate is processed by the grinding wheel for each specified rotation angle of the chuck table.