US-12617032-B2 - Systems and methods for controlling wafer breakage during ingot slicing operations

US12617032B2US 12617032 B2US12617032 B2US 12617032B2US-12617032-B2

Abstract

A system for slicing wafers from a monocrystalline semiconductor ingot includes a wire saw, a bond beam, the monocrystalline semiconductor ingot, and two sacrificial disks. The wire saw includes a wire web and wire guides operable to drive the wire web during a slicing operation. The bond beam is connected to the wire saw. The wire saw is operable to move the bond beam in a movement direction towards the wire web during the slicing operation to slice the wafers from the ingot. The ingot includes longitudinal end faces and a circumferential edge extending between the longitudinal end faces. The ingot is attached to the bond beam along the circumferential edge. One sacrificial disk is positioned adjacent each of the longitudinal end faces of the ingot to inhibit uncontrolled breakage of the wafers during the slicing operation.

Inventors

Jung-Chiang Liao
Yi-Chun Chou
Liang-Chin Chen
Chin-Yu Chang
Ming-Tao Chia
Peter D. Albrecht

Assignees

GLOBALWAFERS CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20230721

Claims (20)

1 . A system for slicing wafers from a monocrystalline semiconductor ingot, the system comprising: the monocrystalline semiconductor ingot; a wire saw including a wire web and wire guides operable to drive the wire web during a slicing operation; a bond beam connected to the wire saw, the wire saw operable to move the bond beam towards the wire web during the slicing operation to slice the wafers from the ingot; the monocrystalline semiconductor ingot comprising longitudinal end faces and a circumferential edge extending between the longitudinal end faces, the ingot attached to the bond beam along the circumferential edge; and two sacrificial disks, wherein one sacrificial disk is positioned adjacent each of the longitudinal end faces of the ingot to inhibit uncontrolled breakage of the wafers during the slicing operation, wherein the ingot has an outer ingot diameter and the sacrificial disks each have an outer disk diameter that is smaller than the outer ingot diameter, wherein an outer circumferential edge of each sacrificial disk is attached to the bond beam such that each sacrificial disk is axially offset from a longitudinal axis of the adjacent longitudinal end face.
2 . The system of claim 1 , wherein the sacrificial disks are made of semiconductor material.
3 . The system of claim 1 , wherein each sacrificial disk is adhered to the adjacent longitudinal end face with an adhesive.
4 . The system of claim 1 , wherein each sacrificial disk is adhered to the bond beam with an adhesive.
5 . The system of claim 1 , wherein the monocrystalline semiconductor ingot is a monocrystalline silicon ingot.
6 . The system of claim 5 , wherein the monocrystalline silicon ingot has a (110) crystal plane positioned perpendicular to a movement direction of the ingot towards the wire web.
7 . The system of claim 6 , wherein the wafers sliced from the monocrystalline silicon ingot are (100) monocrystalline silicon wafers.
8 . The system of claim 7 , wherein the sacrificial disks are made of monocrystalline silicon.
9 . The system of claim 8 , wherein at least one of the sacrificial disks has a (110) crystal plane positioned at an oblique angle to the movement direction.
10 . The system of claim 9 , wherein the at least one of the sacrificial disks has the (110) crystal plane positioned at an angle of between 30° to 60° to the movement direction.
11 . The system of claim 9 , wherein the at least one of the sacrificial disks has the (110) crystal plane positioned at an angle of 45° to the movement direction.
12 . The system of claim 8 , wherein each of the sacrificial disks has a (110) crystal plane positioned at an oblique angle to the movement direction.
13 . The system of claim 12 , wherein each of the sacrificial disks has the (110) crystal plane positioned at an angle of between 30° to 60° to the movement direction.
14 . The system of claim 12 , wherein each of the sacrificial disks has the (110) crystal plane positioned at an angle of 45° to the movement direction.
15 . The system of claim 1 , wherein the sacrificial disks each have a thickness of greater than 500 μm.
16 . The system of claim 15 , wherein the sacrificial disks each have the thickness of greater than 800 μm.
17 . The system of claim 1 , wherein the sacrificial disks each have a thickness of between 500 μm to 2000 μm.
18 . The system of claim 1 , wherein the sacrificial disks each have a thickness of between 800 μm to 1600 μm.
19 . The system of claim 1 , wherein each of the sacrificial disks has a different outer disk diameter.
20 . The system of claim 1 , wherein each of the sacrificial disks has an outer disk diameter of between 150 mm and 250 mm and the ingot has an outer ingot diameter of between 300 mm and 450 mm.

Description

FIELD This disclosure relates generally to wire saw processes used to slice monocrystalline semiconductor ingots into wafers and, more specifically, to systems and methods for controlling breakage of wafers sliced from an ingot during a wire saw process. BACKGROUND Single crystal silicon, which is the starting material for most processes for the fabrication of many electronic components such as semiconductor devices and solar cells, is commonly prepared by batch Czochralski (CZ) or Continuous Czochralski (CCZ) methods. In these methods, a polycrystalline source material, such as polycrystalline silicon (“polysilicon”), in the form of solid feedstock material is charged to a quartz crucible and melted, a single seed crystal is brought into contact with the molten silicon or melt, and a single crystal (or monocrystalline) silicon ingot is grown by slow extraction. Monocrystalline silicon wafers may be sliced from a monocrystalline silicon ingot using a wire saw machine. The ingot is connected to a structure of the wire saw by a bond beam and an ingot holder. The ingot is bonded along its circumferential edge with adhesive to the bond beam. The bond beam is in turn bonded with adhesive to the ingot holder. The ingot holder is connected by any suitable fastening system to the wire saw structure. The ingot is suspended from or “hangs” from the bond beam and the ingot holder in the wire saw, such that the longitudinal end faces of the ingot extend perpendicular to the bond beam. During a slicing operation, the circumferential edge of the ingot is contacted by a web of moving or translating wires in the wire saw that slice the ingot into silicon wafers. Silicon wafers sliced from proximate the longitudinal end faces of the ingot may be inadvertently damaged or experience uncontrolled wafer breakage during the wire saw operation. Wafer breakage during the wire saw operation reduces the number of wafers produced from the ingot, creates manufacturing inefficiencies, increases costs, and decreases wafer yield. Accordingly, there exists a need for practical, cost-effective systems and methods that facilitate reducing or eliminating wafer damage or breakage during a wire saw operation. This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, these statements are to be read in this light, and not as admissions of prior art. SUMMARY One aspect is a system for slicing wafers from a monocrystalline semiconductor ingot. The system includes a wire saw that includes a wire web and wire guides operable to drive the wire web during a slicing operation. The system also includes a bond beam connected to the wire saw. The wire saw is operable to move the bond beam in a movement direction towards the wire web during the slicing operation to slice the wafers from the ingot. The system also includes the monocrystalline semiconductor ingot. The ingot includes longitudinal end faces and a circumferential edge extending between the longitudinal end faces. The ingot is attached to the bond beam along the circumferential edge. The system also includes two sacrificial disks. One sacrificial disk is positioned adjacent each of the longitudinal end faces of the ingot to inhibit uncontrolled breakage of the wafers during the slicing operation. Another aspect is a method of slicing wafers from a monocrystalline semiconductor ingot. The method includes attaching a circumferential edge of the ingot to a bond beam and positioning sacrificial disks adjacent longitudinal end faces of the ingot. One sacrificial disk is positioned adjacent each of the longitudinal end faces. The method also includes connecting the bond beam to a wire saw that includes a wire web and performing a slicing operation on the ingot by operating the wire saw to drive the wire web and move the bond beam and the ingot in a movement direction towards the wire web to slice the wafers from the ingot. The sacrificial disks operate to inhibit uncontrolled breakage of the wafers during the slicing operation. Various refinements exist of the features noted in relation to the above-mentioned aspects. Further features may also be incorporated in the above-mentioned aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to any of the illustrated embodiments may be incorporated into any of the above-described aspects, alone or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of a wafer slicing system including an ingot and a wire saw; FIG. 2 is a front elevation of the ingot attached to the wire saw; FIG. 3 is a perspective of the ingot; FIG. 4 is