JPH0469529B2 - - Google Patents

Description

[Detailed Description of the Invention] <Field of Application> This invention is applicable to cutting ingots of silicon or the like, which are raw materials for manufacturing semiconductor devices, into sections using a rotating blade, or when slicing semiconductor wafers from ingots. This invention relates to an ingot cutting device.

<Prior art> Silicon and other ingots used in semiconductor devices are made of brittle material, so if one side is held or pressed and cut with a blade, the weight of the cut piece on the cutting side and the cutting blade will be reduced in the final area of cutting. The stress load on the uncut portion increases due to adhesion to the blade, etc., and it is likely that the blade will break off due to a so-called cracking state and chipping before the cutting by the blade is completed.

For example, in the process of pulling and manufacturing silicon single crystals, the structure, physical properties, etc. differ depending on the region at the growth interface, so in order to use the optimal region for the semiconductor to be obtained, sample cutting or section cutting is required. It is necessary to do the following. However, since ingots are expensive, it is obvious that the smaller the cutting loss, the better; however, chips as described above are likely to occur when cutting into sections, and due to these chips, the subsequent wafer slices are cut by the depth of the chip. This would be extremely uneconomical.

In addition, when wafers are obtained by slicing them from ingots, the slice thickness is generally several hundred microns, so in the final region of slicing, the surface tension of the cutting fluid, the weight of the wafer, the effect of the wafer recovery device during recovery, etc. As a result, the above-mentioned chipping is likely to occur, and therefore, the productivity is significantly reduced due to the chipping at the outer periphery where the largest number of semiconductor elements can be obtained from a single wafer.

Therefore, we aim to prevent this problem as much as possible and improve productivity.
The following measures are generally taken to improve yield.

That is, one of them is slice-based attachment.
A waste material made of carbon or the like (hereinafter referred to as the slice base) is attached to a part of the side surface of the ingot in the longitudinal direction by gluing or the like, and cutting is performed from the side facing the slice base, and the slice base is cut at the end. (For example, see Japanese Patent Application Laid-Open No. 61-65749).

According to this method, the problem of loss of ingots and wafers is temporarily resolved, but it requires work such as preparing the slice base in advance, attaching it, and removing it from the wafer after cutting. Therefore, it is necessary to select materials that do not have any negative effects.

Therefore, although the attachment of slice bases has some advantages in preventing loss of ingots and wafers, the presence of slice bases that are ultimately discarded is something that needs improvement in this respect. Ta.

Next, as the second means, in addition to the rotation of the blade, there is also rotation of the ingot, especially regarding wafer slicing (see, for example, Japanese Patent Laid-Open No. 147312/1983). When the ingot is rotated, it is cut from the periphery toward the center, so there is no loss at the outer periphery, where productivity is high, and there is no need for a slicing base, which is an advantage. In terms of device performance, even higher precision and functionality will be required.

That is, when recovering sliced wafers,
When the above-mentioned slicing base is attached, the wafer may be gripped or held by suction with a vacuum chuck at the stage of cutting the base, but in the case of ingot rotation, the wafer must be gripped or suctioned at least immediately before the cutting is completed. If this happens, the wafer may shake or twist due to the suction, etc., resulting in a chip in the center.To solve these problems, for example, synchronization and concentric rotation of the gripping or suction mechanism, and skillful contact with the wafer. It is necessary to measure the concentric rotation with the chuck side (face), especially when there are shape defects such as flatness of the ingot end face or perpendicularity to the axis of rotation, as in the case of the first cutting. In this respect, the accuracy, function, and maintenance of the device as a whole were difficult. In addition, in the case of this ingot rotation, a so-called "belly button" protrusion is likely to occur unless the center of the wafer is chipped, and in this case, post-processing to remove it is complicated. .

<Object of the present invention> The present invention has been provided in view of the above-mentioned conventional problems.In a method in which the ingot base is fixed and only the blade is rotated, the ingot base side as well as the cutting side are A vacuum chuck that adheres to the shape of the suction grip is fixed in advance before the start of cutting, and cutting is started while holding that position, and the holding is released when taking it out after cutting is completed. By doing so, the aim is to eliminate the need for a slicing base, prevent damage to wafers and ingots, and improve economic efficiency and quality.

<Example> Hereinafter, preferred examples of the present invention will be described based on the drawings.

Although FIGS. 1 to 3 show the case of a horizontal cutting machine (slicing machine) in which the ingot W is placed horizontally, there is no particular difference in carrying out the present invention in a so-called vertical cutting machine. In the figure, 1 is a table slidably provided on the top surface of the device main body B, and a spacer 2
An ingot W, which is an object to be cut, is placed through the ingot. 3 is a clamper that firmly presses (fixes) the main body side of the ingot W, that is, the side (substrate) that is cut out during cutting. Known means such as a method of gripping the part can be used. 4 is an inner peripheral blade type blade (hereinafter referred to as a blade) in which diamond particles or the like are bound to the inner peripheral side of a donut-shaped thin disk to serve as a cutting blade;
The WS is a wafer that is sequentially cut out to a desired thickness from an ingot base W by sliding the table 1 with respect to the blade 4. The figure shows a state where an inclined end face is formed at the beginning of cutting. 5 is table 1 facing the above wafer WS.
This is a chuck device that suctions and grips the wafer by means of a vacuum chuck 6 disposed above and provided at the tip thereof, and the vacuum chuck 6 is connected via a vacuum hose 7 to a vacuum pump (not shown). However, Bakyumu Chuck 6 is
As shown in FIG. 2 from the suction surface side, it is composed of a large number of chucks 6a (six in the figure) whose suction surfaces have a small diameter of, for example, about 20 mm. , are arranged concentrically so as to evenly scatter and attract the entire surface of the wafer according to the diameter of the ingot (wafer) to be attracted and held.

FIG. 3 shows a specific example of the construction of one of the many vacuum chucks mentioned above.

In the figure, a vacuum rod 61 passing through the chuck device base 51 has a vacuum hose 7 connected to its rear end and a pad support ball 62 connected to its front end (tip). A vacuum housing 63 is attached to the support ball 62 so as to sandwich the support ball between mounting nuts 64, facing the wafer WS to be cut out, and a lip 65 made of a soft material is further attached to the housing. There is. The vacuum housing 63 has a ventilation hole 63a, which together with the lip 65 forms a suction pad that applies negative pressure to the area surrounded by the lip 65 to suction the wafer. Therefore, if the wafer contact surface of the vacuum housing is soft, the pad can be made without the lip. In addition, this suction pad is attached to the support ball 62.
It is provided so that it can be tilted, that is, swingable. Reference numeral 52 denotes a spring that always presses and advances the vacuum rod 61 toward the ingot (wafer) within the base 51, thereby alleviating the contact impact when the chuck 6 is slid and positioned toward the ingot at the beginning of setting. Reference numeral 53 denotes a locking device for fixing the vacuum rod 61 at a predetermined position so that it cannot move forward or backward, and is preferably one that can be operated by a required automatic mechanism, such as a piston rod of an air cylinder.

When using the above-described configuration as a wafer slicing machine as shown in FIG. 1, the ingot W is first placed on the table 1 and fixed immovably by the clamper 3. In the case of wafer slicing, the end face of the ingot W is usually formed flat in advance, so after the above-mentioned fixation, the chuck device 5 is slid toward the ingot, and the vacuum chuck 6 is
is fixed in a position where it is in contact with the end face of the ingot,
The vacuum chuck 6 is adsorbed by the vacuum pump. This "adsorption" means that the lip 65 of the vacuum chuck 6 or the vacuum housing 6
The elasticity of the 3rd layer etc. acts to prevent even the slightest movement toward the chuck side or the ingot base side, that is, to balance the suction pressure with the elastic force of the lip. For example, the above object can be achieved if the lip 65 is made of a very flexible thin rubber material and the vacuum housing 63 is made of a soft resin material or the like with a flat contact surface.

After the abutting and fixing, the locking device 53 is operated to lock the vacuum rod 61 immovably.

After completing this locking operation, the blade 4 is rotated to cut the ingot W into a wafer WS of a required thickness.

However, in the final area of ingot cutting (see Figure 3), since the thickness of the blade 4 is different between the inner circumferential cutting edge, which is the cutting edge, and the other main body part, the blade main body part, the wafer WS, and the ingot base part are different in thickness. A slight gap A is created between the cut surface on the W side. Cutting water and air are present in this gap A, and since the blade 4 rotates at a high speed, stress is generated on the wafer WS side, which has low rigidity, due to surface tension, negative pressure, etc.

Conventionally, the wafer WS would wobble due to this surface tension, etc., and stress concentration would occur in the remaining part of the cut, resulting in wafer chipping, but in the present invention, the cut side (wafer) follows the shape of the ingot from the beginning of cutting. are integrally fixed by the chuck device 5, so that the negative pressure due to the gap A,
All stress due to surface tension etc. is transmitted to the ingot base W and the chuck device 5 side. In other words, the wafer WS, which is integrally and fixedly held by the chuck device 5, does not wobble at any position during the cutting process, so stress greater than the wafer rigidity is not concentrated on the remaining part of the cutting. Therefore, the wafer can be completely cut without chipping. After the cutting is completed, the chuck device is moved to release the adsorption and lock, and the wafer is recovered by conventionally known means.

According to the above, the suction pad for the wafer is provided so that it can swing, but even if the suction end surface of the ingot is tilted as shown in the illustration, this swing will absorb it and ensure that the ingot is suctioned and fixed. On the other hand, there is a concern that the wafer may wobble during cutting due to this oscillation, but it can be fixed by tightening the mounting nut 64, or as described above, it can be fixed evenly on the suction end surface by using multiple chucks. Since the wafer can be fixed as a whole by being scattered in the area, the wafer does not wobble, and since the wafer is attracted to a small area, no adverse effects such as stress on the attraction surface occur.

Next, although the former embodiment is a wafer slicing machine, the configuration of the first embodiment can also be implemented in an apparatus for cutting ingots as shown in FIG.

As mentioned above, the ingot is subjected to sample cutting, section cutting, etc. before wafer slicing. The ingot at the time of this cutting has a substantially conical shape with a tapered shape, especially at one end, as shown in the figure. Therefore, if the degree of swing of the vacuum chuck 6 and the suction pad portion are adjusted to correspond to the sloped portion of the ingot, the end portion can be gripped and fixed by suction.

<Effect> As explained in detail above, according to the present invention,
When cutting an ingot into sections or slicing it into wafers, a vacuum chuck that sucks the cut side of the ingot in addition to the base part of the ingot according to the shape of the suction grip is used to fix the ingot immovably before starting cutting and maintain that state. Therefore, the cutting stress caused by the cutting progress of the blade is transmitted and dispersed to the immovable ingot base side and the cutting side fixing means, and therefore, the cutting stress is transmitted and dispersed in the final area of cutting. There is no chance of chipping from the cut remaining portion before the cutting is completed, which improves the yield. Furthermore, as described above, according to the present invention, it is possible to prevent the occurrence of chipping, so the slicing base, which was used only for preventing chipping, can be made unnecessary. In addition to reducing costs, the processes from attachment to removal after cutting and disposal are no longer necessary, and workability and productivity can be improved, resulting in significant effects on economy and quality. Furthermore, according to the present invention, the object can be achieved by adding a suction gripping device to the conventional structure, and the reliability of the device can be improved.

[Brief explanation of the drawing]

The figures show a preferred embodiment of the present invention, and FIG. 1 is a schematic diagram of the main parts of a slicing machine according to the first embodiment, FIG. 2 is a schematic front view of the vacuum chuck surface, and FIG. The figure is an enlarged explanatory view of an example of the construction of a vacuum chuck device, and FIG. 4 is a schematic diagram of the main parts of the slicing machine of FIG. 1 applied to an ingot categorization and cutting machine. 1... Ingot mounting table, 3... Clamper, 4... Inner peripheral blade, 5,100... Vacuum chuck device, W... Ingot, WS
...Wafer.

Claims (1)

[Scope of Claims] 1. In an ingot cutting device that rotates a blade to cut an ingot whose proximal end is fixed, a plurality of ingots are arranged so as to be movable forward and backward facing the end face of the fixed ingot on the cutting surface side. a vacuum rod; a suction pad tiltably disposed at the tip of the vacuum rod via a spherical bearing; a reduced pressure suction means for generating suction force on each suction pad via the vacuum rod and the suction pad; An ingot cutting device comprising: locking means for fixing each vacuum rod so that it cannot move forward or backward, and each vacuum rod is fixed in a state where the suction pad is attracted to the end face of the ingot when cutting the ingot.