Method for improving warping of small-size multi-line cutting silicon wafer
By controlling the steel wire speed and wire usage in the NTC slicer, the warping problem of small-sized silicon wafers was solved and the flattening effect of the silicon wafer morphology was achieved.
Patent Information
- Application Number
- CN202511213036.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-28
- Publication Date
- 2025-10-21
AI Technical Summary
In existing technologies, when NTC slicing machines cut small-sized silicon wafers, the wire speed and wire quantity cannot be precisely controlled, resulting in uncontrollable silicon wafer warping and poor morphology.
By controlling the wire speed and reducing the amount of wire used, the wire entry and exit speeds are stabilized. The amount of wire used at different positions is adjusted to reduce the thickness difference between the entry and exit positions of the silicon wafer, thus ensuring a flat silicon wafer morphology.
The warpage control of small-sized silicon wafers in NTC slicers is achieved, the flatness of the silicon wafers is improved, and the warpage phenomenon is reduced.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of multi-wire cutting, and in particular relates to a method for improving the warping of a small-size multi-wire cut silicon wafer. Background Art
[0002] With the rapid development of industries such as semiconductors, photovoltaics, and precision manufacturing, the demand for high-precision and high-efficiency cutting processes is increasing. Diamond wire slicing technology has gradually become the mainstream cutting process due to its advantages such as high cutting accuracy, low material loss, and environmental protection.
[0003] Diamond wire slicing is mainly completed by a slicer, which is mainly composed of a processing chamber, a wire chamber, a mortar tank and other electrical control parts; a main roller that can rotate at high speed is installed in the processing chamber, and multiple circles of steel wire are wrapped around the main roller to form a diamond wire net. The crystal ingot is fixed above the wire net with a clamp. During the processing, the clamp carries the crystal ingot down and contacts with the high-speed rotating wire net to gradually slice it; for slicing, NTC slicers are mainly used. Two wire wheels for new and old wires and multiple small wire wheels are installed in the wire chamber of the NTC slicer. During the cutting process, the steel wire reciprocates between the new and old wires; when the steel wire runs at high speed, the diamond wire net contacts and grinds the crystal ingot, and when the processing table drives the clamped crystal ingot to feed downward, the crystal ingot can be cut.
[0004] At present, in addition to the size of the warp value, downstream users pay more attention to the relative flatness of the silicon wafer microstructure in terms of parameter requirements for small-sized silicon wafer rough slices. In the existing technology, the NTC slicer machine processing program sets the steel wire speed as the instantaneous speed, but after the processing is completed, the parameter extraction steel wire speed is the average speed during the processing. The two cannot be compared, and the warping of the silicon wafer during the processing is uncontrollable, resulting in poor silicon wafer morphology. Summary of the Invention
[0005] In view of this, the present invention provides a method for improving the warpage of small-size multi-wire saw silicon wafers.
[0006] The technical solution adopted by the present invention to solve its technical problem is: A method for improving the warpage of small-sized multi-wire-cut silicon wafers. When an NTC slicer is used to cut silicon wafers, the speed of the steel wire is controlled and the amount of steel wire used is reduced. This allows the steel wire to enter and exit the blade at a stable speed, reduces the difference in thickness between the wafer entry and exit positions and the thickness in the middle of the wafer, and results in a relatively flat wafer topography.
[0007] Preferably, during the cutting process, the steel wire speed remains unchanged, and the steel wire consumption refers to the wire consumption at the steel wire entry position, the steel wire cutting position, and the steel wire exit position. The wire consumption at the steel wire entry position and the steel wire exit position are lower than the wire consumption at the steel wire cutting position.
[0008] Preferably, the steel line speed is 1150m / min~1250m / min.
[0009] Preferably, the wire usage at the steel wire entry position and the steel wire exit position is specifically as follows: the wire usage at the steel wire entry position refers to the wire feed amount and wire retreat amount at the steel wire entry position, the wire usage at the steel wire cutting position refers to the wire feed amount and wire retreat amount at the steel wire cutting position, the wire usage at the steel wire exit position refers to the wire feed amount and wire retreat amount at the steel wire exit position, the wire feed amount at the steel wire entry position, cutting position and exit position are all less than the wire retreat amount at the steel wire entry position, cutting position and exit position, the wire feed amount and wire retreat amount at the steel wire entry position gradually increase, the wire feed amount and wire retreat amount at the steel wire cutting position remain stable, and the wire feed amount and wire retreat amount at the steel wire exit position gradually decrease.
[0010] Preferably, the wire feeding rate at the steel wire entry position is 407m / min-607m / min, the wire feeding rate at the steel wire cutting position is 607m / min, and the wire feeding rate at the steel wire exit position is 607m / min-450m / min.
[0011] The wire withdrawal amount at the steel wire entry position is 388m / min-578m / min, the wire withdrawal amount at the steel wire cutting position is 578m / min, and the wire withdrawal amount at the steel wire exit position is 578m / min-428m / min.
[0012] Preferably, the steel wire entry position is -2 mm - (1% to 1.5% of the crystal rod diameter) mm, the steel wire cutting position is (1% to 1.5% of the crystal rod diameter) mm - (75% to 85% of the crystal rod diameter) mm, and the steel wire exit position is (75% to 85% of the crystal rod diameter) mm - (crystal rod diameter + 10) mm.
[0013] Preferably, the size of the silicon wafer is 4 inches, 5 inches or 6 inches.
[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for improving warpage of small-size multi-wire cut silicon wafers. When an NTC slicer is used to cut silicon wafers, the steel wire speed is controlled and the amount of steel wire used is reduced, so that the steel wire entry speed and the steel wire exit speed are stable, the contact area between the steel wire and the silicon wafer gradually increases and then gradually decreases, and the difference between the thickness at the entry position and the exit position of the silicon wafer and the thickness at the middle position of the silicon wafer is reduced. The silicon wafer is less likely to warp at the exit position and the entry position, and the silicon wafer has a relatively flat morphology. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 This is a graph of steel line speed in Example 1 and Comparative Example 1.
[0016] Figure 2 This is a diagram of the steel wire usage in Example 1 and Comparative Example 1.
[0017] Figure 3 This is a silicon wafer morphology image of Example 1.
[0018] Figure 4 This is a silicon wafer morphology image of comparative example 1.
[0019] In the figure: the original process refers to the process of comparative example 1, and the improved process refers to the process of embodiment 1. DETAILED DESCRIPTION
[0020] The technical solutions and technical effects of the embodiments of the present invention are further elaborated below in conjunction with the accompanying drawings of the present invention.
[0021] A method for improving the warpage of small-sized multi-wire-cut silicon wafers. When an NTC slicer is used to cut silicon wafers, the speed of the steel wire is controlled and the amount of steel wire used is reduced. This allows the steel wire to enter and exit the blade at a stable speed, reduces the difference in thickness between the wafer entry and exit positions and the thickness in the middle of the wafer, and results in a relatively flat wafer topography.
[0022] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for improving warpage of small-size multi-wire cut silicon wafers. When an NTC slicer is used to cut silicon wafers, the steel wire speed is controlled and the amount of steel wire used is reduced, so that the steel wire entry speed and the steel wire exit speed are stable, the contact area between the steel wire and the silicon wafer gradually increases and then gradually decreases, and the difference between the thickness of the silicon wafer at the entry position and the silicon wafer exit position and the thickness at the middle position of the silicon wafer is reduced, the silicon wafer exit position and the entry position are less likely to warp, and the silicon wafer morphology is relatively flat.
[0023] Furthermore, during the cutting process, the steel wire speed remains unchanged, and the steel wire consumption refers to the wire consumption at the steel wire entry position, the steel wire cutting position, and the steel wire exit position. The wire consumption at the steel wire entry position and the steel wire exit position are lower than the wire consumption at the steel wire cutting position.
[0024] Furthermore, the steel line speed is 1150m / min~1250m / min.
[0025] In existing technology, due to the advantages of NTC diamond wire cutting machines, such as high output and high cutting efficiency, the instantaneous speed of the steel wire must be increased to a high and stable running state. According to the current cutting level, 1200m / min is the optimal speed for small-sized silicon wafers. However, if the steel wire speed is too fast, it is easy to cause line marks on the surface of the silicon wafer with strong cutting ability. The NTC machine program sets the steel wire speed as the instantaneous speed of the steel wire. After the machine runs, it outputs the average speed of the steel wire. It is impossible to control the steel wire speed in real time. Therefore, the instantaneous speed of the steel wire is fixed, and the reciprocating motion cycle is changed by adjusting the advance and retreat lines. This not only simplifies the subsequent process optimization work, but also makes the cutting morphology of the silicon wafer relatively flat.
[0026] Furthermore, the wire usage at the steel wire entry position and the steel wire exit position is specifically as follows: The wire usage at the wire entry position refers to the wire feed and wire withdrawal amount at the wire entry position, the wire usage at the wire cutting position refers to the wire feed and wire withdrawal amount at the wire cutting position, and the wire usage at the wire exit position refers to the wire feed and wire withdrawal amount at the wire exit position; The wire feeding amount at the steel wire entry position, cutting position and knife exit position is less than the wire retreat amount at the steel wire entry position, cutting position and knife exit position. The wire feeding amount and wire retreat amount at the steel wire entry position gradually increase, the wire feeding amount and wire retreat amount at the steel wire cutting position remain stable, and the wire feeding amount and wire retreat amount at the steel wire exit position gradually decrease.
[0027] Furthermore, the wire feeding rate at the steel wire entry position is 407m / min-607m / min, the wire feeding rate at the steel wire cutting position is 607m / min, and the wire feeding rate at the steel wire exit position is 607m / min-450m / min.
[0028] The wire withdrawal amount at the steel wire entry position is 388m / min-578m / min, the wire withdrawal amount at the steel wire cutting position is 578m / min, and the wire withdrawal amount at the steel wire exit position is 578m / min-428m / min.
[0029] Furthermore, the steel wire entry position is -2mm-(crystal rod diameter 1%~1.5%) mm, the steel wire cutting position is (crystal rod diameter 1%~1.5%) mm-(crystal rod diameter 75%~85%) mm, and the steel wire exit position is (crystal rod diameter 75%~85%) mm-(crystal rod diameter + 10) mm.
[0030] For example, for a 6-inch crystal rod, the steel wire entry position is -2mm-12mm, the steel wire cutting position is 12mm-120mm, and the steel wire exit position is 120mm-160mm.
[0031] For a 5-inch crystal rod, the steel wire entry position is -2mm-18mm, the steel wire cutting position is 18mm-102mm, and the steel wire exit position is 102mm-137mm.
[0032] For a 4-inch crystal rod, the steel wire entry position is -2mm-16mm, the steel wire cutting position is 16mm-80mm, and the steel wire exit position is 80mm-110mm.
[0033] Furthermore, the size of the silicon wafer is 4 inches, 5 inches or 6 inches.
[0034] The present invention is described through the following examples and comparative examples.
[0035] Example 1: Use NTC slicer to cut 6-inch ingot, cut with slurry, the cutting fluid flow rate is 120N / MIN and the parameters remain unchanged. The steel wire speed during cutting is as follows: Figure 1 As shown, the amount of steel wire used is as follows Figure 2 As shown, after cutting, the morphology of the silicon wafer is as follows Figure 3 shown.
[0036] Comparative Example 1: Use NTC slicer to cut 6-inch ingot, cut with slurry, the cutting fluid flow rate is 120N / MIN and the parameters remain unchanged. The steel wire speed during cutting is as follows: Figure 1 As shown, the amount of steel wire used is as follows Figure 2 As shown, after cutting, the morphology of the silicon wafer is as follows Figure 4 shown.
[0037] Depend on Figure 3 、 Figure 4 It can be seen that by controlling the steel wire speed to be stable and reducing the amount of steel wire used, the warping of the silicon wafer at the entry and exit positions of the knife is improved, and the morphology of the silicon wafer cut by the present invention is flatter than that of the silicon wafer cut by the comparative example.
[0038] The above disclosure is only a preferred embodiment of the present invention, and it is certainly not intended to limit the scope of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.
Claims
1. A method for improving the warpage of small-size multi-wire sawing silicon wafers, characterized in that: When the NTC slicer cuts silicon wafers, by controlling the steel wire speed and reducing the amount of steel wire used, the steel wire entry speed and exit speed are stable, the difference in thickness between the silicon wafer entry position and the silicon wafer exit position and the thickness in the middle of the silicon wafer is reduced, and the silicon wafer morphology is relatively flat.
2. The method for improving warpage of small-size multi-wire sawing silicon wafers according to claim 1, wherein: During the cutting process, the steel wire speed remains unchanged, and the steel wire consumption refers to the wire consumption at the steel wire entry position, the steel wire cutting position, and the steel wire exit position. The wire consumption at the steel wire entry position and the steel wire exit position is lower than the wire consumption at the steel wire cutting position.
3. The method for improving warpage of small-size multi-wire sawing silicon wafers according to claim 2, wherein: The steel wire speed is 1150m / min~1250m / min.
4. The method for improving warpage of a small-size multi-wire saw silicon wafer according to claim 2 or 3, wherein: The wire usage at the steel wire entry position and the steel wire exit position is specifically as follows: the wire usage at the steel wire entry position refers to the wire entry amount and wire withdrawal amount at the steel wire entry position, the wire usage at the steel wire cutting position refers to the wire entry amount and wire withdrawal amount at the steel wire cutting position, the wire usage at the steel wire exit position refers to the wire entry amount and wire withdrawal amount at the steel wire exit position, the wire entry amount at the steel wire entry position, the cutting position and the steel wire exit position are all less than the wire withdrawal amount at the steel wire entry position, the cutting position and the steel wire exit position, the wire entry amount and wire withdrawal amount at the steel wire entry position gradually increase, the wire entry amount and wire withdrawal amount at the steel wire cutting position remain stable, and the wire entry amount and wire withdrawal amount at the steel wire exit position gradually decrease.
5. The method for improving warpage of small-size multi-wire sawing silicon wafers according to claim 4, wherein: The wire feeding rate of the steel wire entry position is 407m / min-607m / min, the wire feeding rate of the steel wire cutting position is 607m / min, and the wire feeding rate of the steel wire exit position is 607m / min-450m / min; The wire withdrawal amount at the steel wire entry position is 388m / min-578m / min, the wire withdrawal amount at the steel wire cutting position is 578m / min, and the wire withdrawal amount at the steel wire exit position is 578m / min-428m / min.
6. The method for improving warpage of a small-size multi-wire sawing silicon wafer according to any one of claims 2 to 5, wherein: The steel wire entry position is -2mm-(crystal rod diameter 1%~1.5%) mm, the steel wire cutting position is (crystal rod diameter 1%~1.5%) mm-(crystal rod diameter 75%~85%) mm, and the steel wire exit position is (crystal rod diameter 75%~85%) mm-(crystal rod diameter + 10) mm.
7. The method for improving warpage of small-size multi-wire sawing silicon wafers according to claim 1, wherein: The size of the silicon wafer is 4 inches, 5 inches or 6 inches.