JP5886522B2 - Wafer production method - Google Patents

Description

  The present invention relates to a wafer production method for producing a wafer on which a chamfering process of an outer peripheral portion and a process of forming a mark indicating a crystal orientation are performed from a cylindrical crystal ingot.

  In a general manufacturing process of semiconductor devices such as IC and LSI, a wafer serving as a base is formed by slicing an ingot, and then the outer peripheral portion of the wafer is chamfered or crystal orientation such as an orientation flat or notch is formed. The process which forms the mark to show is performed. Then, after mirror processing on both surfaces of the wafer and formation of circuits on the wafer surface, individual device chips are formed by dicing. In recent years, production of device chips using small-diameter wafers has been demanded in order to meet the demand for production of a small variety of products.

Japanese Patent Laid-Open No. 5-6881

  However, if each wafer sliced from an ingot is individually chamfered or processed to form a crystal orientation mark such as an orientation flat or notch, the work becomes complicated and the productivity is low. There was a problem. This problem is particularly noticeable for small diameter wafers.

  The present invention has been made to solve such a problem, and a technical problem thereof is to efficiently perform processing for forming a chamfer of the outer peripheral portion of the wafer and a mark indicating a crystal orientation.

The present invention relates to a wafer production method for producing a wafer having a chamfered outer periphery and a process for forming a mark indicating a crystal orientation from a cylindrical crystal ingot. The diameter of the end face is 1.0 inch or less. An ingot forming step of forming a cylindrical crystal ingot that is a circle of the chamfer, and a chamfered groove forming step of forming a chamfered groove on the outer periphery of the crystal ingot at intervals corresponding to the thickness of one wafer after the ingot forming step, and After the ingot forming step and the chamfered groove forming step, a marking step for forming a plane parallel to the outer tangent surface of the crystal ingot on the outer periphery of the crystal ingot as a mark indicating the crystal orientation, a chamfered groove forming step and a marking step After that, a wire saw is cut into the crystal ingot along the chamfering groove, and a slice for slicing the crystal ingot into a wafer is obtained. And a scan step, the surface to be formed in the marking step is formed in a position shallower than the horizontal depth of the chamfered groove.
In this wafer production method, in the chamfering groove forming step, a blade whose tip is sharpened in a V shape is used, the width of the chamfering groove is larger than the cross-sectional diameter of the wire saw, the side surface of the chamfering groove and the outer periphery of the ingot It is preferable to form a chamfered groove so that the angle with respect to the tangential surface is an obtuse angle.

The present invention also includes a device forming process for forming a device on a wafer produced by the above production method, and a laminating process for aligning a plurality of wafers on the basis of the external shape after the device forming process and bonding them in multiple layers. This is a method for forming a laminated device .

  In the present invention, since the chamfering groove forming process and the marking process are performed before the slicing process, the chamfering process and the marking process can be performed in a state before slicing the wafer. Therefore, since it is not necessary to perform chamfering and marking individually on each wafer, the work is not complicated and productivity can be improved.

  In addition, when trying to stack a plurality of conventional large workpieces such as wafers having a diameter of 12 inches, for example, the outline blurring was large and alignment could not be performed on the basis of the outline. If it is a wafer, it is possible to make the outer shape blur within an allowable range. Therefore, it is possible to perform alignment on a plurality of wafers at the same time on the basis of the outer shape, and to improve the productivity of stacking a plurality of wafers. .

  Furthermore, when a mark indicating the crystal orientation, which is a surface formed in the marking process, is formed in a chamfer groove on the outer periphery of the ingot, this mark is formed even on the flat surface of the wafer like a conventional orientation flat or notch. As such, the entire flat surface of the wafer can be used to form the device.

It is a perspective view which shows an example of a crystal ingot. It is sectional drawing which shows an example of the state which forms a chamfering groove | channel in the outer peripheral surface of a crystal ingot. It is a figure which shows an example of the state which forms the mark which shows a crystal orientation on the outer peripheral surface of a crystal ingot. It is sectional drawing which shows the state which slices a crystal ingot into a some wafer. It is a perspective view which shows a some wafer. It is a perspective view which shows the wafer in which the device was formed in the surface. It is a perspective view which shows the state which aligns and laminate | stacks several wafers on the external shape reference | standard. It is a perspective view which shows the state in which the wafer was bonded together in multiple.

(1) Ingot forming step A crystal ingot 1 shown in FIG. 1 is manufactured by growing a crystal by, for example, the Czochralski method, and is formed in a cylindrical shape. The end face 10 of the crystal ingot 1 is formed in a circular shape and has a diameter of 1.0 inch or less. The crystal ingot 1 is not particularly limited, and examples thereof include a silicon ingot, a gallium arsenide ingot, a silicon carbide ingot, and a sapphire ingot.

(2) Chamfering groove forming process After the ingot forming process, the rotating cutting blade 2 is brought into contact with the outer peripheral surface 11 of the crystal ingot 1 as shown in FIG. The cutting blade 2 is a bevel blade whose tip section is sharpened in a V shape.

  The crystal ingot 1 is rotated about the vertical axis, and the cutting blade 2 is rotated about the vertical axis and moved in the radial direction (arrow A direction) of the crystal ingot 1 to approach the crystal ingot 11 for cutting. When cutting is performed by bringing the blade edge of the blade 2 into contact with the outer peripheral surface 11, a chamfer groove 12 having a triangular cross section is formed on the outer peripheral surface 11.

  The chamfered grooves 12 are formed at intervals corresponding to the thickness of one wafer. For example, when a wafer having a thickness of 1 mm is cut out later, the chamfer grooves 12 are sequentially formed at intervals of 1 mm by performing cutting while feeding the cutting blade 2 by 1 mm in the vertical direction.

(3) Marking Step After the ingot forming step, a mark indicating the crystal orientation is formed on the outer peripheral surface 11 of the crystal ingot 1. For example, as shown in FIG. 3, when the planar mark 13 is formed as a mark indicating the crystal orientation, the grinding wheel 3 formed in a cylindrical shape is rotated around a horizontal axis extending in the left-right direction in FIG. The mark 13, which is a plane parallel to the tangential surface of the outer peripheral surface 11, is formed by bringing the crystal ingot 1 close to the radial direction (arrow B direction) and bringing it into contact with the outer peripheral surface 11. The mark 13 is desirably formed shallower than the horizontal depth of the chamfered groove 12. That is, the mark 13 is desirably formed in the chamfered groove 12 of the outer peripheral surface 11 of the crystal ingot 1. By forming the mark 13 in this way, the wafer end face 10 cut out in a subsequent slicing step is formed. Since the mark 13 does not erode a flat surface that is not chamfered, all the flat surfaces can be used for device formation in a subsequent device formation process.

  In addition, as long as a chamfering groove formation process and a marking process are after an ingot formation process, whichever may be performed first.

(4) Slicing step After the chamfering groove forming step and the marking step, as shown in FIG. 4, the wire saw 4 is cut into the crystal ingot 1 in the horizontal direction (arrow C direction) along the chamfering groove 12. As shown in FIG. 5, the crystal ingot 1 is sliced into a plurality of wafers W. As shown in FIG. 4, when the chamfering grooves 12 are formed so that the groove width Y of the chamfering grooves 12 is larger than the diameter X of the cross section of the wire saw 4, as shown in FIG. A chamfered portion 120 is formed on the outer peripheral portion of the wafer W. The chamfer groove 12 also serves as a guide for the wire saw 4. In particular, by forming the chamfered groove 12 so that the groove width Y of the chamfered groove 12 is larger than the diameter X of the cross section of the wire saw 4 as shown in FIG. Will improve.

  In this manner, a plurality of wafers W on which the chamfered portion 120 is formed on the outer peripheral portion and the marks 13 that are marks indicating the crystal orientation are formed are produced from the cylindrical crystal ingot 1. In the chamfering groove forming step, a bevel blade formed in a V shape is used, and therefore, as shown in FIG. Becomes obtuse. Therefore, the strength of each individual wafer W cut out is high.

  The wafer W is not particularly limited, and examples thereof include a semiconductor wafer such as a silicon wafer, gallium arsenide, and silicon carbide, and a sapphire inorganic material substrate, depending on the type of crystal ingot.

(5) Device Formation Step After the slicing step, the surface W1 of each wafer W is mirror-finished to form a plurality of devices D as shown in FIG. The device D is formed by a technique such as photolithography, for example. The plurality of devices D are formed in an area partitioned by the street S.

(6) Lamination process After the device formation process, as shown in FIG. 7, the laminated body 5 shown in FIG. 8 can be formed by laminating a plurality of wafers W and bonding them in multiple layers. In the stacking, the vertical positions of the device D and the street S can be aligned by aligning the wafers W on the basis of the external shape. For example, if the mark 13 is positioned on a straight line in the vertical direction, the vertical positions of the device D and the street S automatically match. Since the wafer W is a small-diameter wafer having a diameter of 1.0 inch or less, the blurring of the outer shape at the time of stacking can be within an allowable range, and the alignment can be performed collectively on the basis of the outer shape. The productivity of stacking can be improved. Note that the types of devices D formed on each wafer may be different as long as they have the same size.

  As described above, according to the above procedure, the chamfering groove forming process and the marking process are performed before the slicing process, so that the chamfering process and the marking process can be performed in a state before slicing into the wafer W. Therefore, since it is not necessary to perform chamfering and marking individually for each wafer W, the work is not complicated and productivity can be improved.

1: Crystal ingot 10: End face 11: Peripheral surface 12: Chamfer groove 120: Chamfer 13: Mark 2: Cutting blade 3: Grinding wheel 4: Wire saw 5: Laminate W: Wafer W1: Surface D: Device S: Street

Claims (3)

From a cylindrical crystal ingot, a wafer production method for producing a wafer subjected to chamfering of an outer peripheral portion and processing to form a mark indicating a crystal orientation,
An ingot forming step of forming a cylindrical crystal ingot whose end face is a circle having a diameter of 1.0 inch or less;
After the ingot forming step, a chamfer groove forming step of forming a chamfer groove on the outer periphery of the crystal ingot at intervals corresponding to the thickness of one wafer,
After the ingot forming step and the chamfered groove forming step, a marking step for forming a plane parallel to a tangential surface of the outer periphery of the crystal ingot as a mark indicating a crystal orientation on the outer periphery of the crystal ingot;
After the chamfering groove forming step and the marking step, a slicing step of slicing the crystal ingot into a wafer by cutting a wire saw into the crystal ingot along the chamfering groove;
The surface formed in the marking step is formed at a position shallower than the horizontal depth of the chamfer groove.
Wafer production method. In the chamfering groove forming step, a blade having a V-shaped sharp tip is used, and the width of the chamfering groove is larger than the cross-sectional diameter of the wire saw, and the side surface of the chamfering groove and the outer periphery of the ingot are Forming the chamfer groove so that the angle with the tangential surface becomes an obtuse angle;
The wafer production method according to claim 1. A device forming step of forming a device on the wafer produced by the production method according to claim 1 or 2,
After the device forming step, a plurality of the wafers are aligned with each other on the basis of the outer shape, and a laminating step for laminating the wafers,
A method for forming a laminated device comprising:

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