Crystal bar processing method and wafer
Technical Field
The invention belongs to the technical field of semiconductors, and particularly relates to a processing method of a crystal bar and a wafer.
Background
Monocrystalline silicon, also known as silicon single crystal, is the most basic material in electronic information materials and belongs to the class of semiconductor materials. Single crystal silicon is mainly used for semiconductor integrated circuits, diodes, epitaxial wafer substrates, and solar cells.
In the processing of a single crystal silicon wafer, please refer to fig. 1, the main processing process includes: crystal growth (Growing), Ingot outside diameter Grinding (Ingot Grinding), truncation (Band Saw), Ingot crystal Orientation testing (Ingot X-Ray), crystal Orientation adjustment (Ingot Orientation adjustment), adhesion workpiece plate (Ingot Mounting), Ingot wire cutting (Wiresaw), slice Cleaning (As Sliced Cleaning), chamfering (Edge Grinding), double-sided Grinding (Lapping), Polishing (Polishinging), Cleaning (Cleaning), and the like. In the processing process of the crystal bar, the section crystal orientation of the crystal bar obtained by cutting is unknown, so that the crystal bar cannot be directly cut into pieces, and the crystal orientation of the crystal bar needs to be adjusted after crystal orientation test, so as to ensure that the crystal orientation of the surface of the cut wafer is the target crystal orientation. The wafer formed after cutting needs to be chamfered and ground due to the problem of edge damage, so as to achieve the purposes of removing the damaged layer on the edge of the wafer and achieving the target diameter.
However, in this process, the edge of the ingot is affected by the cutting line and the mortar when being cut into pieces, so that a damaged layer is likely to appear, and the next step of processing is required after chamfering, which results in a problem that the process time is long and secondary damage is likely to occur.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a processing method of a crystal bar and a wafer. The technical problem to be solved by the invention is realized by the following technical scheme:
a method for processing a crystal bar comprises the following steps:
detecting the original crystal orientation of the crystal bar to obtain a detection result;
determining a preset crystal orientation of the crystal bar according to the detection result;
forming a plurality of convex parts which are arranged at intervals and have preset shapes on the surface of the crystal bar with the preset crystal orientation;
and cutting the crystal bar along the depth direction of the groove part between two adjacent convex parts to obtain a plurality of wafers with the preset shape.
In one embodiment of the invention, detecting the original crystal orientation of the crystal bar to obtain a detection result comprises:
detecting the original crystal orientation of the crystal bar;
and obtaining the detection result according to the angle deviation between the original crystal orientation of the crystal bar and the preset crystal orientation, wherein the detection result comprises that the angle deviation is a preset deviation and the angle deviation is greater than the preset deviation.
In one embodiment of the invention, detecting the original crystal orientation of the crystal bar comprises:
and detecting the original crystal orientation of the crystal bar by using an X-ray detection method.
In an embodiment of the present invention, determining the preset crystal orientation of the ingot according to the detection result includes:
and when the detection result is that the angle deviation is a preset deviation, setting the original crystal orientation of the crystal bar as the preset crystal orientation, and when the detection result is that the angle deviation is greater than the preset deviation, adjusting the original crystal orientation of the crystal bar to the preset crystal orientation.
In one embodiment of the present invention, the predetermined shape includes a predetermined size and a predetermined edge profile.
In an embodiment of the present invention, forming a plurality of convex portions with a predetermined shape and arranged at intervals on the surface of the ingot with the predetermined crystal orientation includes:
according to the preset size of the wafer and the preset edge appearance are right the surface of the crystal bar is simultaneously subjected to multi-channel chamfering and outer diameter grinding treatment, so that the surface of the crystal bar is formed to be arranged at intervals and is provided with the preset size and the preset edge appearance the plurality of protruding parts.
In an embodiment of the present invention, before cutting the ingot in a depth direction of the groove portion between two adjacent convex portions to obtain a plurality of wafers having the predetermined shape, the method further includes:
and carrying out truncation processing on the crystal bar with the plurality of convex parts.
In one embodiment of the present invention, cutting the ingot along a depth direction of the groove portion between two adjacent convex portions to obtain a plurality of wafers having the predetermined shape includes:
and with the groove part as a cutting position, cutting the crystal bar along the depth direction of the groove part by using a multi-wire cutting method to obtain the wafer with the preset shape.
In an embodiment of the invention, after cutting the crystal bar along the depth direction of the groove part between two adjacent convex parts to obtain a plurality of wafers, the method further comprises the following steps:
and carrying out double-sided grinding treatment on the wafer.
An embodiment of the present invention further provides a wafer, which is prepared by using the dicing method according to any one of the above embodiments.
The invention has the beneficial effects that:
the processing method of the crystal bar provided by the invention comprises the steps of firstly detecting the original crystal orientation of the crystal bar, adjusting the crystal orientation according to the original crystal orientation, then forming a plurality of protruding parts which are arranged at intervals and have preset shapes on the surface of the crystal bar, and then cutting the crystal bar along the depth direction of the groove part between two adjacent protruding parts to obtain a wafer with a required shape. The processing method of the invention has the advantages that the edge of the prepared convex part has the required shape and outline of the wafer, so the edge of the wafer does not need to be cut after the wafer is formed, a damaged layer caused by cutting can not appear, and the cut wafer can be directly subjected to an outer diameter grinding process, thereby shortening the process flow.
The present invention will be described in further detail with reference to the accompanying drawings and examples.
Drawings
FIG. 1 is a schematic flow chart of a method for processing a crystal bar provided by the prior art;
FIG. 2 is a schematic flow chart illustrating a method for processing a crystal bar according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart illustrating another method for processing a crystal ingot according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an X-ray detection apparatus according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of an ingot according to an embodiment of the present invention before performing a plurality of chamfering and outer diameter grinding processes;
FIG. 6 is a schematic diagram of an ingot according to an embodiment of the present invention after performing a plurality of chamfering and outer diameter grinding processes;
FIG. 7 is a schematic diagram of a process for cutting a seed rod according to an embodiment of the present invention;
fig. 8 is a schematic diagram of another ingot cutting process according to an embodiment of the present invention.
Description of reference numerals:
x-ray emission terminal-001; x-ray receiving terminal-002; crystal bar-003; physical axis-004; actual crystal orientation-005; chamfering and grinding device-006; cutting line-007; workpiece plate-008; resin strip-009.
Detailed Description
The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.
Example one
Referring to fig. 2, fig. 2 is a schematic flow chart illustrating a method for processing a crystal bar according to an embodiment of the invention. The present embodiment provides a method for processing a crystal bar, including steps 1 to 4, where:
step 1, detecting the original crystal orientation of a crystal bar to obtain a detection result;
step 2, determining a preset crystal orientation of the crystal bar according to the detection result;
step 3, forming a plurality of convex parts which are arranged at intervals and have preset shapes on the surface of the crystal bar with the preset crystal orientation;
and 4, cutting the crystal bar along the depth direction of the groove part between two adjacent convex parts to obtain a plurality of wafers with preset shapes.
Specifically, because the crystal bar forms a plurality of wafers after the wire-electrode cutting, and the wafers are susceptible to the influence of the wire-electrode cutting process, damage layers such as cracks are easy to appear on the edges of the wafers, and if the damage layers cannot be removed in time and the surfaces of the wafers are directly ground, the problems of wafer breakage and the like are easy to appear. Therefore, at present, the outer diameter of the crystal bar is generally ground in the processing process so as to reserve a certain grinding amount for removing the edge damage layer after slicing. In the processing mode, damage caused by cutting cannot be avoided, meanwhile, the process flow is long, the processing cost of the wafer is high, and secondary damage caused in the edge grinding process cannot be avoided.
Therefore, after the ingot needing to be processed is obtained, the embodiment of the invention firstly detects the original crystal orientation of the ingot, obtains a detection result according to the detected original crystal orientation, the detection result is used for judging whether an included angle between the crystal orientation of the ingot needing to be processed and a physical axis is within a preset deviation range, then the crystal orientation of the ingot can be adjusted to a preset crystal orientation according to the detection result, the preset crystal orientation is the crystal orientation required when the ingot is finally processed into a wafer, after the preset crystal orientation of the ingot is determined, a plurality of protruding parts which are arranged at intervals and have preset shapes can be formed on the surface of the ingot, namely, in the step, the outer diameter of the ingot can be processed to the required size and the edge shape of the ingot can be processed to the required shape, the preset shape can be the outer diameter, the edge shape and the like corresponding to each protruding part, so that the outer diameter and the shape of the ingot are processed simultaneously in the step, the convex parts processed by the step can correspond to the wafer formed after subsequent cutting, so that the crystal bar can be directly cut along the depth direction of the groove part between two adjacent convex parts, and the wafer with the preset shape is finally obtained.
In summary, in the embodiment of the invention, the crystal orientation of the crystal bar is firstly measured, the crystal orientation of the crystal bar is ensured to be the preset crystal orientation according to the detection result, the convex parts which are arranged at intervals and have the preset shape are formed on the crystal bar, and finally the cutting line is cut in by the groove part, so that the contact with the edge of the crystal bar is avoided, an edge damage layer is not generated, meanwhile, the groove part has a certain guiding effect, the cutting line can rapidly enter the cutting surface, the cutting efficiency is improved, the edge of the cut wafer is round and smooth, chamfering and grinding are not needed, the subsequent processing technology can be directly carried out, and the technological process is reduced.
Before step 4, the method for processing an ingot provided in this embodiment may further include: the ingot with a plurality of convex parts is subjected to a cutting process.
Specifically, in the actual production process, the length of the ingot obtained through the crystal growth process is large, so that the ingot is generally required to be subjected to the cutting process before the slicing process is performed, at present, the ingot is generally subjected to the cutting process after the outer diameter grinding process, the above process is only rough size processing, and the subsequent step is to perform the segmentation cutting into the wafer according to the physical axial direction. Referring to fig. 3, in this embodiment, the crystal orientation of the ingot is measured before the ingot is cut, so that a problem of a large amount of loss of the cut ingot due to crystal orientation deviation is avoided.
Example two
In this embodiment, a detailed description is given to the processing method of the ingot provided by the present invention on the basis of the above embodiments, wherein step 1 in the first embodiment may specifically include:
step 1.1, detecting the original crystal orientation of a crystal bar;
specifically, after the ingot to be processed is obtained, the original crystal orientation of the ingot can be detected, for example, the original crystal orientation of the ingot can be detected by an X-ray detection method.
Further, referring to fig. 4, for example, the X-ray detection apparatus provided in fig. 4 may be used to detect the crystal orientation deflection angle of the ingot, wherein 001 is an X-ray transmission terminal, 002 is an X-ray reception terminal, 003 is the detected ingot, 004 is a physical axis, 005 is an actual crystal orientation, and during detection, crystal orientation measurement is performed by X-ray, so that the deflection angle between the crystal orientation of the ingot and the physical axis can be determined, and generally, the crystal orientation and the physical axis have a deviation of 0 to 0.5 °, and the deviation needs to be corrected.
Step 1.2, obtaining a detection result according to the angle deviation between the original crystal orientation and the preset crystal orientation of the crystal bar, wherein the detection result comprises that the angle deviation is the preset deviation and the angle deviation is larger than the preset deviation.
Specifically, after the original crystal orientation of the crystal bar is obtained, an angle deviation between the original crystal orientation of the crystal bar and a preset crystal orientation can be obtained, and a detection result can be obtained according to the angle deviation, wherein the detection result comprises that the angle deviation is the preset deviation and the angle deviation is greater than the preset deviation, the preset deviation is a deviation within an error range, and when the angle deviation is greater than the preset deviation, the angle between the crystal orientation of the crystal bar and the physical axis exceeds the error range, and the angle needs to be adjusted.
In a specific embodiment, the step 2 in the first embodiment may specifically include:
and when the detection result is that the angle deviation is greater than the preset deviation, adjusting the original crystal orientation of the crystal bar to the preset crystal orientation.
That is, when the detected angle deviation is the preset deviation, it indicates that the angle deviation is within the error range, and the original crystal orientation of the crystal bar can be directly used as the preset crystal orientation without adjusting the crystal orientation of the crystal bar, so as to perform the subsequent processing procedure; and when the detected angle deviation is greater than the preset deviation, it indicates that the angle deviation between the original crystal orientation of the crystal bar and the preset crystal orientation is large, and the crystal orientation of the crystal bar needs to be adjusted to a proper angle, that is, the original crystal orientation of the crystal bar is adjusted to the preset crystal orientation, so that the cutting surface of the subsequent crystal bar is perpendicular to the physical crystal orientation.
In a specific embodiment, the preset shape in the step 2 in the first embodiment includes a preset size and a preset edge profile, where the preset size is an outer diameter of the protruding portion, and the preset edge profile is a profile at an edge of the protruding portion, then the step 2 in the first embodiment may specifically include:
and simultaneously carrying out a plurality of chamfering and outer diameter grinding treatments on the surface of the crystal bar according to the preset size and the preset edge shape of the wafer so as to form a plurality of protruding parts which are arranged at intervals and have the preset size and the preset edge shape on the surface of the crystal bar.
Specifically, after the preset size and the preset edge morphology of the wafer obtained after cutting are determined, the crystal orientation of the crystal bar can be adjusted to be the preset crystal orientation, the crystal bar is subjected to multiple chamfering and outer diameter grinding treatments simultaneously, after the multiple chamfering and outer diameter grinding treatments are performed, protruding parts arranged at intervals can be formed on the surface of the crystal bar, each protruding part is formed by simultaneously performing chamfering and outer diameter grinding, and therefore each protruding part has the preset size and the preset edge morphology, and after each protruding part is cut into pieces, the wafer meeting the size and shape requirements can be directly obtained.
In one embodiment, please refer to fig. 5 and 6, wherein 003 in fig. 5 and 6 is a boule, 006 is a chamfering and grinding device, fig. 5 is a state before grinding, and fig. 6 is a state after grinding, the chamfering and grinding device is used for forming a plurality of protruding portions which are arranged at intervals and have a preset size and a preset edge profile on the surface of the boule, so that a grinding wheel which can simultaneously perform chamfering and outer diameter grinding is arranged on the chamfering and grinding device, and a plurality of protruding structures are arranged at intervals on the grinding wheel, and the chamfering and grinding device can be adjusted according to the preset size and the preset edge profile of the boule. After the crystal orientation is adjusted and simultaneously subjected to chamfering and outer diameter grinding, the ground crystal bar has the edge appearance of a wafer, and the crystal orientation of the ground crystal bar can be kept consistent with the actually required crystal orientation. The surface of the crystal bar after chamfering and outer diameter grinding has the appearance as shown in fig. 7, wherein the convex part is the edge required by the wafer, and the concave part is the cut-in direction of the subsequent multi-line cutting process, and the formula (1) is calculated according to the thickness of the wafer:
Tickness=wire pitch-wire diameter-Sic size*3 (1)
for example, according to the current general process requirements of 300mm silicon wafers, the thickness (TiCkness) of the cut wafer is 900 μm, the wire diameter is 140 μm, and the SiC model #1500 (D508.4 μm), the distance between two adjacent groove parts after the crystal bar is processed by chamfering and outer diameter grinding is 1065 μm, and the width of each groove part is 165 μm.
It should be noted that the embodiment of forming the plurality of convex portions on the ingot at intervals by the chamfering and grinding apparatus shown in fig. 5 and 6 is merely exemplary and not intended as a specific limitation of the present invention with respect to the form of the chamfering and grinding apparatus.
In a specific embodiment, after a plurality of convex parts which are arranged at intervals and have preset sizes and preset edge shapes are formed on the surface of the crystal bar, the crystal bar can be cut off, so that the problem that a large amount of loss of the cut crystal bar is caused by crystal direction deviation can be solved.
In a specific embodiment, the step 4 in the first embodiment may specifically include:
and cutting the crystal bar along the depth direction of the groove part by using the groove part as a cutting position by using a multi-wire cutting method to obtain the wafer with a preset shape.
Specifically, referring to fig. 8, in which 007 is a cutting line, 008 is a workpiece plate, 009 is a resin strip, before cutting, a crystal bar to be cut is firstly adhered to the workpiece plate, then the cutting line takes the groove portion as a cutting position, and the crystal bar is cut along the depth direction of the groove portion by using a multi-line cutting method, so that a wafer with a preset size and a preset edge profile can be directly obtained, in this embodiment, because the groove portion is taken as the cutting position, contact between the cutting line and the edge of the convex portion is avoided, and thus an edge damage layer is not generated, and because the groove portion has a certain guiding effect, the cutting line can rapidly enter the cutting surface by taking the groove portion as the cutting position, cutting efficiency is improved, and the edge of the wafer obtained after cutting does not need to be chamfered and ground because the edge has the required profile, the wafer appearance can not be damaged for the second time, and then the surface grinding process can be directly carried out, thereby saving the process steps.
In one embodiment, the ingot may be cut and then subjected to a double-side lapping process to ensure that the thickness of each wafer is as desired.
In the embodiment of the invention, after the original crystal orientation of the crystal bar is adjusted to be the preset crystal orientation, by simultaneously carrying out a plurality of chamfering and outer diameter grinding treatments on the surface of the crystal bar, so as to form a plurality of convex parts which are arranged at intervals and have preset sizes and preset edge shapes on the surface of the crystal bar, and the concave part is used as a cutting position for line cutting, and finally the wafer with the preset size and the preset edge appearance is obtained, the mode can ensure that the crystal orientation of the crystal bar meets the actual crystal orientation requirement, meanwhile, the cutting line can be prevented from directly contacting with the edge of the wafer, the edge damage is avoided, and multiple chamfering and outer diameter grinding treatments are simultaneously carried out on the surface of the crystal bar, so that the process steps of carrying out chamfering treatment again in the follow-up process can be reduced, the secondary damage caused by chamfering treatment is avoided, the process steps can be saved, and the processing efficiency of the crystal bar is improved.
EXAMPLE III
In this embodiment, on the basis of the above embodiment, a wafer processed by the ingot processing method provided in the above embodiment is further provided, and the processing method specifically includes:
step 1, detecting the original crystal orientation of a crystal bar to obtain a detection result;
step 2, determining a preset crystal orientation of the crystal bar according to the detection result;
step 3, forming a plurality of convex parts which are arranged at intervals and have preset shapes on the surface of the crystal bar with the preset crystal orientation;
and 4, cutting the crystal bar along the depth direction of the groove part between two adjacent convex parts to obtain a plurality of wafers with preset shapes.
The implementation principle and technical effect of the processing method for the crystal bar provided by the embodiment of the invention are similar to those of the processing method in the embodiment, and are not described again here.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.