Scribing method of single-shaft scribing machine for releasing stress and reducing edge and corner breakage

Abstract

The invention discloses a scribing method for relieving stress and reducing edge and corner breakage of a single-shaft scribing machine. Relates to the technical field of semiconductor processing. Comprising a slotting and semi-cutting process, and the slotting and semi-cutting process mainly comprises the following steps: step 1, fixing a wafer on a scribing machine loading table tray loaded with a wide knife, and setting the vertical design width of a single chip on the wafer as a, the transverse design length as b, the film thickness as t and the wafer thickness as d; setting the cutting depth of the slotting semi-cutting process as x, and setting the cutting height as t + d-x; 2, the wafer is cut in the horizontal direction, the vertical step diameter distance is a * m, m is the line number of the pipe core included between the two continuously cut tool marks in the group, and m is a positive integer larger than or equal to 1; according to the invention, the cutting difficulty is reduced, and the cost burden caused by purchasing a double-shaft scribing machine for slotting and cutting is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor processing technology, and in particular to a dicing method for releasing stress of a single-axis dicing machine and reducing edge and corner collapse. Background Art

[0002] As the integration of semiconductor chips increases, the process becomes more complicated. The dicing blocks are no longer just for one material (such as Si, GaAs, etc.). Oxides, nitrides, metals, etc. will also be placed in the blocks. At the same time, the chip size, thickness, and dicing block width are also shrinking. The resulting dicing edge and corner chipping anomalies are also increasing, making it difficult to guarantee the dicing yield.

[0003] The dual-axis dicing machine uses two knives to cut during the cutting process, and the stress is released equally. At the same time, wide knives and narrow knives can be used for slotting step-by-step cutting. However, due to the high price of dual-axis dicing machine equipment, most semiconductor chip manufacturers currently use single-axis dicing machines as the main dicing equipment. Although single-axis dicing machines are cheap, they are significantly inferior to dual-axis dicing equipment in dicing stress release, and the dicing quality is therefore not as good as dual-axis dicing equipment, especially on small chips. The dual-axis dicing machine uses a wide knife to cut the grooves, and then another narrow knife cuts through, so that the surface stress is released in time. Even if a single-axis dicing machine performs slotting distribution cutting, it is necessary to use a wide knife to open all the slots for the first time, and then switch to a narrow knife for cutting. However, when a wide knife is used to make grooves on a single-axis dicing machine for the first time, if the normal continuous cutting method is used, it is easy to cause problems such as chip edge collapse, corner collapse, and cracking. Therefore, how to process on a single-axis dicing machine, release dicing stress, and reduce chip collapse is a technical problem that needs to be solved urgently in this case.

[0004] In response to the above problems, the existing patent documents, such as the invention patent of "A method for dicing a semiconductor device chip wafer" applied for and published on December 18, 2018, with application number 201810778531, disclose the following solutions: The area of ​​the required tube core is set to be a micron*a micron, the distance between two adjacent cutters in the X direction is equal to an integer multiple m of the side length of the tube core (including the dicing spacing), and the distance between two adjacent cutters in the Y direction is equal to an integer multiple n of the side length of the tube core, specifically including the following steps: Step S1: First, a knife mark X1 is made along the X direction at the center line of the first row of tube core gaps as the starting line of the first group of X-direction scribing in the X direction, and then the scribing is performed from left to right in sequence with the starting line X1 as the initial starting point along the X direction according to a step distance of a*m microns until the scribing in the X direction is completed; Step W1: Rotate 90° clockwise, then make a cut Y1 along the Y direction at the center line of the first row of tube core gaps as the starting line of the first group of Y-direction cutters in the Y direction, and then scribing from left to right in the Y direction with the starting line Y1 as the initial starting point according to the step distance of a*n microns until the Y direction scribing is completed; Step S2: Rotate 90° counterclockwise to return to the X direction, and make a cut along the X direction at a distance of a micrometer from X1 as the starting line X2 of the second set of X-direction cutters in the X direction, and then scribing from left to right in the X direction with the starting line X2 as the initial starting point according to the step distance of a*m micrometers until the scribing in the X direction is completed; Step W2: Rotate 90° clockwise back to the Y direction, and make a cut along the Y direction at a distance of a micron from Y1 as the starting line Y2 of the second group of Y-direction cutters in the Y direction. Then, scribing is performed from left to right in the Y direction with the starting line Y2 as the initial starting point according to a*n micron step distance until the scribing in the Y direction is completed; Step SM: rotate 90° counterclockwise back to the X direction, and make a cut along the X direction with a distance of (m-1)*a microns from X1 as the starting tangent line Xm of the mth group of X-direction cutters in the X direction, and then scribing from left to right in the X direction with the starting tangent line Xm as the initial starting point according to the step distance of a*m microns until the scribing in the X direction is completed; Step WN: Rotate 90° clockwise back to the Y direction, and make a cut along the Y direction at a distance of (n-1)*a microns from Y1 as the starting tangent line Yn of the nth group of Y-direction cutters in the Y direction. Then, along the Y direction, use the starting tangent line Yn as the initial starting point to scribing from left to right in a*n micron steps until the Y direction scribing is completed; scribing is completed.

[0005] For example, in the existing patent literature, there is an invention patent for "A method for dicing ultra-thin wafers" applied for and published on July 27, 2021, with application number 2021103697262, which mainly discloses the following technical solutions: 1) Put a film on the back of the wafer and bake it in a 60°C to 80°C oven for 10 to 30 minutes; 2) Take out the baked wafer and cool it naturally to room temperature, then place the wafer with the film on the ceramic work plate of the dicing machine and turn on the vacuum; 3) Install the dicing knife on the spindle of the dicing machine and complete the knife trimming and height measurement procedures; 4) Use the process parameters of spindle speed 20000~40000r / min, feed speed 20~40mm / s to cut the wafer along the horizontal direction, i.e. CH1 direction, with a step spacing of N*b, where b represents the grain width, N=2, 3, 4...; 5) Use the process parameters of spindle speed 20000~40000r / min, feed speed 40~80mm / s to cut the wafer along the longitudinal direction, i.e., CH2 direction, with a step spacing of N*a, where a represents the grain length, N=2, 3, 4...; 6) Use the process parameters of spindle speed 20000~40000r / min, feed speed 20~40mm / s to cut the wafer CH3 direction, the step spacing is (N-1)*b, where b represents the grain width, N=2, 3, 4...); 7) Use the process parameters of spindle speed 20000~40000r / min, feed speed 40~80mm / s to cut the wafer CH4 direction, and the step spacing is (N-1)*a, where a represents the grain length, N=2, 3, 4...; 8) Repeat steps 4) and 5) until the wafer is diced into the core target size axb.

[0006] The above-mentioned existing patent documents mainly adopt a one-time cutting method. In the cutting direction of the first surface, since the cutting size is still small, the problem of edge and corner chipping on the back side in this direction is difficult to avoid. As the cutting size requirements decrease, this problem will become more serious and cannot be completely solved. Summary of the invention

[0007] In view of the above problems, the present invention provides a dicing method for reducing edge and corner chipping problems during cutting by releasing stress of a single-axis dicing machine.

[0008] The technical solution of the present invention is: A dicing method for releasing stress of a single-axis dicing machine and reducing edge and corner chipping includes a slotting and half-cutting process, which mainly includes the following steps: Step 1: fix the wafer on the dicing machine stage with a wide blade, set the vertical design width of a single chip on the wafer to be a, the horizontal design length to be b, the film thickness to be t, and the wafer thickness to be d; set the cutting depth of the slotting half-cutting process to be x, and the cutting height to be t+dx; Step 2: Cut the wafer in the horizontal direction, with a vertical step distance of a*m, where m is the number of rows of dies between two consecutive cuts of this group, and m is a positive integer ≥1; Step 3, rotating the stage 90 degrees counterclockwise, cutting the wafer in the vertical direction, with a horizontal step distance of b*n, where n is the number of columns of dies included between two consecutive cuts of this group, and n is a positive integer ≥1; Step 4: Rotate the stage 90 degrees clockwise to cut the wafer horizontally, with a vertical step distance of a*m, and use the cutting path with a distance a from the previous group of horizontal starting cutting paths as the starting cutting path of this group; Step 5: Rotate the stage 90 degrees counterclockwise to cut the wafer vertically. The horizontal step distance is b*n. The cutting path with a vertical starting cutting path distance of b in the previous group is used as the starting cutting path of this group. Cutting is completed from top to bottom in sequence. Repeat the above steps 4 and 5 until m groups are cut horizontally and n groups are cut vertically; after all the cutting is completed, the full cutting process is performed.

[0009] Specifically, the full cutting process includes: Step A, remove the wafer with the surface cut, fix the wafer on the dicing machine stage with the narrow blade loaded, set the cutting depth of the full cutting process to y, and the corresponding cutting height to t+dy, where y is in the reference range of (d+1 / 5t)~(d+1 / 2t); Step B: Cut the wafer in the horizontal direction, with a vertical step distance of a, and cut the current horizontal direction in sequence from the starting cutting line from top to bottom or from bottom to top along the Y direction according to the step distance a; Step C: Rotate the stage plate 90 degrees to cut the wafer in the vertical direction, with a horizontal step distance of b. Cut the current vertical direction in sequence from the starting cutting line from top to bottom or from bottom to top along the X direction at a step distance of b. At this point, all cutting is completed and the wafer and film can be removed for washing and drying.

[0010] Specifically, m is a positive integer not less than 1.

[0011] Specifically, n is a positive integer not less than 1.

[0012] Specifically, m and n are not 1 at the same time.

[0013] Specifically, the value of m is 3, and the value of n is 2.

[0014] Specifically, a wide blade is first used to perform a slotting half-cutting process on a single-axis dicing machine, and then a narrow blade is switched to perform a full-cutting process.

[0015] Specifically, the width of the blade used in the slotting half-cutting process is greater than the width of the blade used in the full-cutting process.

[0016] Specifically, the wide blade has a width of 30-50 μm, and the narrow blade has a width of 15-25 μm.

[0017] Specifically, in step 1, the cutting height is t+dx, where x is d / 3~d / 2.

[0018] The present invention combines a wide knife with a narrow knife, and first uses the wide knife to combine small-sized tube cores into large-sized units for slotting and cutting. On the one hand, the cutting method of combining into large tube core units can effectively release surface stress and prevent problems such as edge and corner collapse of the entire surface. At the same time, it can solve the problems of edge and corner collapse on the back side caused by the one-time cutting in the first cutting direction. At this time, the loss and load of the narrow knife are also reduced, and the impact is small. The abnormal impact such as damage on the back side is also reduced, which reduces the cutting difficulty and reduces the cost burden of purchasing a dual-axis dicing machine for slotting and cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of a and b. Figure 2 It is a structural diagram of step 2; Figure 3 It is a structural diagram of step three; Figure 4 It is a structural diagram of step four; Figure 5 It is a schematic diagram of the structure of step five; Figure 6 This is a schematic diagram of the structure after cutting is completed; Figure 7 This is the front effect picture after cutting in this case; Figure 8 This is a physical picture of a single tube core after cutting in this case; Fig. 9 This is the side view scanned under the electron microscope after cutting in this case; Fig.10 This is a film image with chipped edges and corners after cutting using the background technology method. DETAILED DESCRIPTION

[0020] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "vertical", "horizontal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0022] Reference below Figure 1-9 Describe the present invention, the red line in the figure indicates the cutting position of the current step; The single-axis dicing machine is used to release stress and reduce chipping and corner chipping, including a slotting half-cutting process and a full-cutting process.

[0023] In the first stage of the implementation case, a wide knife was used to make half cuts in 5 directions, and in the second stage, a narrow knife was used to make full cuts.

[0024] Chip vertical ( Figure 1 The design width of the Y vertical direction is a=0.7mm, and the horizontal ( Figure 1 The design length of the X horizontal direction is b=0.7mm, the film thickness is t=0.07mm, and the wafer thickness is d=0.3mm; the cutting depth of the slotting half-cutting process is set to x=0.11mm, and the cutting height is t+dx=0.26mm. The specific expected slotting and cutting steps are as follows Figure 2~Figure 6 As shown, there are two angles of 0° and 90° in the five cutting directions. The 0° cutting direction corresponds to step 3a, which is 2.1mm, and the 90° cutting direction corresponds to step 2b, which is 1.4mm. The angle sequence corresponding to the dicing in the five cutting directions in the figure is 0°→90°→0°→90°→0°. At this time, it should be noted that during the alignment and calibration process after the subsequent workpiece is installed, the order of machine alignment always follows the order of CH1~CH5. Therefore, the two 0° and 90° directions in CH1~CH5 need to be aligned at one time, otherwise switching back and forth will make it impossible to determine the previous group of cutting positions in the current direction. Therefore, in this case, CH1~CH3 are set to 0°, and CH4 and CH5 are set to 90°.

[0025] The main cutting procedures and main operation details of the slotting and half-cutting alignment in this case are as follows: Step I, the main setting parameters of the first stage and the second stage of program 1&2 are shown in Table 1 below: Table 1 Step II: before the operation, replace the dicing machine table with the relevant program settings of "Program 1 Condition (Slotting Half Cutting)" with a wide-blade Kulicke&Soffa S164-E5H0-000 dicing knife (blade width 40-45μm) and complete the knife repair and sharpening work. At this time, the preparation work before the operation is completed; Step III, fix the wafer (the wafer is pre-attached to the film) on the dicing machine stage with the wide blade loaded; Step IV, the stage rotates 0°, and the cut path of wafer CH1 is aligned, and the alignment of CH1 is completed; Step V, the stage does not rotate, the lens moves down one row to perform CH2 alignment, and CH2 alignment is completed; Step VI: the stage does not rotate, the lens moves down one row to perform CH3 alignment, and CH3 alignment is completed; Step VII, the stage rotates 90° to align the cutting path of wafer CH4; alignment of CH4 is completed; Step VIII: the stage does not rotate, and the lens moves downward one line to perform CH5 alignment. CH5 alignment is completed, and all alignment operations are now completed.

[0026] The above is an explanation of the main parameter setting ideas for the implementation of the case program and the details of the first stage slot alignment calibration. The following is a summary of the main cutting steps of the slotting half-cutting process: Step 1: Fix the wafer (pre-attached to the film) on the dicing machine stage with the wide blade loaded, and set the single chip on the wafer vertically ( Figure 1 The design width is a in the Y vertical direction, and the horizontal ( Figure 1 The design length of the horizontal direction (in the middle) is b, the film thickness is t, and the wafer thickness is d; the cutting depth of the slotting half-cutting process is set to x, and the cutting height is t+dx, where x is d / 3~d / 2; Step 2: Cut the wafer in the horizontal direction, with a vertical step distance of a*m, where m is the number of rows of dies between two consecutive cuts of this group, and m is a positive integer ≥ 1. Cut the current horizontal direction in sequence from the top to the bottom along the Y direction at a step distance of a*m from the starting cutting path of this group; Figure 2 As shown, m is 3; Step 3: Rotate the stage 90 degrees counterclockwise to cut the wafer in the vertical direction. The horizontal step distance is b*n, where n is the number of columns of dies between two consecutive cuts of this group. n is a positive integer ≥ 1. Cut the current vertical direction from the top to the bottom along the x direction at a step distance of b*n. Figure 3 As shown, n is 2; Step 4: Rotate the stage 90 degrees clockwise to cut the wafer horizontally. The vertical step distance is a*m. The cutting path with a starting cutting path distance a in the previous group is used as the starting cutting path of this group. Cut the current horizontal direction in sequence from top to bottom at a step distance a*m. Figure 4 As shown, m is 3; Step 5: Rotate the stage 90 degrees counterclockwise to cut the wafer vertically. The horizontal step distance is b*n. The cutting path with a starting cutting path distance b in the previous group of vertical cutting paths is used as the starting cutting path of this group. Cut the current vertical path in sequence from top to bottom at a step distance of b*n. Repeat the above steps 4 and 5 until m groups are cut horizontally and n groups are cut vertically; after all the cutting is completed, the full cutting process is performed.

[0027] Before the full-cutting process, the dicing machine configured with the relevant program settings of "Program 2 Condition (Full Cutting)" is replaced with a narrow-blade DISCO ZH05-SD3500-N1-110BA dicing knife (blade width of about 20μm) and the knife repair and sharpening work is completed. The cut wafer is routinely aligned. The main cutting steps of the machine for the full-cutting process are summarized as follows: Step A, remove the wafer (attached to the film) with the cut surface, fix the wafer (attached to the film) on the stage of the dicing machine loaded with a narrow knife, set the cutting depth of the full cutting process to y, and the corresponding cutting height to t+dy, where y is in the reference range of (d+1 / 5t)~(d+1 / 2t); Step B: Cut the wafer in the horizontal direction, with a vertical step distance of a, and cut the current horizontal direction in sequence from the starting cutting line from top to bottom or from bottom to top along the Y direction according to the step distance a; Step C: Rotate the stage plate 90 degrees to cut the wafer in the vertical direction, with a horizontal step distance of b. Cut the current vertical direction in sequence from the starting cutting line from top to bottom or from bottom to top along the X direction at a step distance of b. At this point, all cutting is completed and the wafer and film can be removed for washing and drying.

[0028] In this case, m is a positive integer not less than 1, n is a positive integer not less than 1, and m and n are not 1 at the same time.

[0029] The value of m is 3, and the value of n is 2.

[0030] On a single-axis dicing machine, a wide blade is first used for the slotting half-cutting process, and then a narrow blade is switched to perform the full-cutting process.

[0031] The width of the blade used in the slotting half-cutting process is greater than that of the blade used in the full-cutting process. In this case, the width of the wide blade is generally in the range of 30~50μm, and the width of the narrow blade is 15~25μm.

[0032] The dicing machine used in this case is a single-axis dicing machine that can set more than two cutting directions, such as the DISCODAD300 series / single-axis DAD3000 series, etc., which is equipped with multiple directions for cross-block dicing. Compared with the conventional dicing method with two directions (90° and 0°) and adjacent cutting orders, the present invention can variably increase the chip size, release stress and reduce chip chipping. At the same time, different blades can be switched twice to perform slotted step-by-step dicing, release stress, avoid front and back chipping, and reduce the cost burden brought by purchasing high-end dicing machines such as dual-axis. Figure 8 , 9 As shown, the top view and the side view of a single tube die after cutting have smooth edges.

[0033] Regarding the contents disclosed in this case, there are a few points that need to be explained: (1) The drawings of the embodiments disclosed in this case only involve the structures involved in the embodiments disclosed in this case. Other structures can refer to the general design; (2) In the absence of conflict, the embodiments and features of the embodiments disclosed in this case may be combined with each other to obtain new embodiments; The above are only specific implementation methods disclosed in this case, but the protection scope of the present disclosure is not limited thereto. The protection scope disclosed in this case should be based on the protection scope of the claims.

Claims

1. A dicing method for releasing stress and reducing edge and corner collapse of a single-axis dicing machine, characterized in that: The method comprises a slotting and half-cutting process, wherein the slotting and half-cutting process mainly comprises the following steps: Step 1: fix the wafer on the dicing machine stage with a wide blade, set the vertical design width of a single chip on the wafer to be a, the horizontal design length to be b, the film thickness to be t, and the wafer thickness to be d; set the cutting depth of the slotting half-cutting process to be x, and the cutting height to be t+dx; Step 2: Cut the wafer in the horizontal direction, with a vertical step distance of a*m, where m is the number of rows of dies between two consecutive cuts of this group, and m is a positive integer ≥1; Step 3, rotating the stage 90 degrees counterclockwise, cutting the wafer in the vertical direction, with a horizontal step distance of b*n, where n is the number of columns of dies included between two consecutive cuts of this group, and n is a positive integer ≥1; Step 4: Rotate the stage 90 degrees clockwise to cut the wafer horizontally, with a vertical step distance of a*m, and use the cutting path with a distance a from the previous group of horizontal starting cutting paths as the starting cutting path of this group; Step 5: Rotate the stage 90 degrees counterclockwise to cut the wafer vertically. The horizontal step distance is b*n. The cutting path with a vertical starting cutting path distance of b in the previous group is used as the starting cutting path of this group. Cutting is completed from top to bottom in sequence. Repeat the above steps 4 and 5 until m groups are cut horizontally and n groups are cut vertically; after all the cutting is completed, the full cutting process is performed.

2. The dicing method for releasing stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: The full cutting process includes: Step A, remove the wafer with the surface cut, fix the wafer on the dicing machine stage with the narrow blade loaded, set the cutting depth of the full cutting process to y, and the corresponding cutting height to t+dy, where y is in the reference range of (d+1 / 5t)~(d+1 / 2t); Step B: Cut the wafer in the horizontal direction, with a vertical step distance of a, and cut the current horizontal direction in sequence from the starting cutting line from top to bottom or from bottom to top along the Y direction according to the step distance a; Step C: Rotate the stage plate 90 degrees to cut the wafer in the vertical direction, with a horizontal step distance of b. Cut the current vertical direction in sequence from the starting cutting line from top to bottom or from bottom to top along the X direction at a step distance of b. At this point, all cutting is completed and the wafer and film can be removed for washing and drying.

3. The dicing method for releasing stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: The m is a positive integer not less than 1.

4. The dicing method for relieving stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: The n is a positive integer not less than 1.

5. The dicing method for relieving stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: The m and n are not 1 at the same time.

6. The dicing method for uniaxial dicing machine for releasing stress and reducing edge and corner chipping according to claim 1, characterized in that: The value of m is 3, and the value of n is 2.

7. The dicing method for relieving stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: On a single-axis dicing machine, a wide blade is first used for the slotting half-cutting process, and then a narrow blade is switched to perform the full-cutting process.

8. The dicing method for relieving stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 7, characterized in that: The wide knife has a width of 30-50 μm, and the narrow knife has a width of 15-25 μm.

9. The dicing method for relieving stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: The half-cutting process uses a wider blade than the full-cutting process.

10. The dicing method for relieving stress and reducing edge and corner chipping of a single-axis dicing machine according to claim 1, characterized in that: In step 1, the cutting height is t+dx, where x is d / 3~d / 2.

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