A Laser Processing Method for MEMS Probe Forming

Abstract

The present invention discloses a laser processing method for forming MEMS probes in the field of semiconductors, comprising the following steps: S1. Measure the included angle between cutting path 1 and cutting path 2 on the metal raw material through a microscope, and respectively measure the overcut lengths A and B in the directions of cutting path 1 and cutting path 2; S2. Extend cutting path 1 and cutting path 2 in the drawing software and make them intersect at a point; S3. Judge and compare the values of lengths A and B, and draw a circle with the larger value of lengths A and B as the radius of the circle, so that the circle is tangent to both cutting path 1 and cutting path 2; S4. Keep the arc between the two points where the circle is tangent to cutting path 1 and cutting path 2, and remove the other arc parts of the circle, so that the arc is connected to cutting path 1 and cutting path 2 to form a complete corrected cutting path. The present invention avoids the overcut phenomenon at the corners during laser cutting, improves the processing efficiency and the quality of workpieces, and has a low process cost.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductors, and particularly relates to a laser processing method for forming MEMS probes. Background Art

[0002] Probes are indispensable components in the packaging and testing process of integrated circuit chips. With the application of MEMS (MicroElectromechanical System) technology in the semiconductor field, the size of probes is developing towards the micron level or even the sub-micron level. The size and precision requirements of probes are getting higher and higher, and the corresponding structure has become more and more complex. In order to adapt to these changes, high-precision femtosecond processing equipment is used to manufacture probes.

[0003] Femtosecond laser cutting technology is a high-precision laser processing technology. Due to its extremely short pulse width, high peak efficiency, and extremely wide spectrum coverage, it has many excellent characteristics that traditional processes do not have in microfabrication and material processing. At the same time, femtosecond laser has an extremely high electric field strength, which is sufficient to ionize the processed material, so that the material in the ionized action area is removed in the form of plasma, and basically no heat energy is generated. It can effectively cut metal materials or non-metal materials, so its application in the industrial production field is becoming more and more extensive.

[0004] However, when using femtosecond laser cutting to make probes, it is necessary to cut metal raw materials through laser to process and obtain probes. When laser cutting probes, cutting tracks (cutting trajectories) will be generated on the raw material. Corners composed of two cutting tracks, horizontal and vertical, often appear on the raw material. In the past, when cutting corners, the laser cut along the two cutting tracks, horizontal and vertical, respectively, and needed to be cut twice. Due to the special position of the corner, in traditional cutting technology, to ensure processing accuracy and cutting stability, when the laser reaches the corner area, the cutting speed of the laser will decrease or stop. At this time, the energy output by the laser will accumulate intensively here. Especially at the intersection of the horizontal and vertical cutting tracks, over-cutting of the corner is likely to occur during the cutting process, resulting in the produced workpiece not meeting the quality requirements. Summary of the Invention

[0005] The purpose of the present invention is to provide a laser processing method for forming MEMS probes. A method of arc transition is introduced to address the over-cutting phenomenon of corners existing in the probe forming process, avoiding the over-cutting phenomenon of corners in the MEMS probe needle shape caused by energy aggregation due to irregular laser spots during laser cutting, improving processing efficiency and workpiece quality, and having low process costs.

[0006] The purpose of the present invention is achieved as follows: A laser processing method for forming MEMS probes includes the following steps:

[0007] S1. Measure the angle between cutting path 1 and cutting path 2 on the metal raw material through a microscope, and measure the overcut lengths A and B in the directions of cutting path 1 and cutting path 2 respectively;

[0008] S2. Extend cutting path 1 and cutting path 2 in the drawing software and make them intersect at a point;

[0009] S3. Compare the values of lengths A and B, and use the larger value of lengths A and B as the radius of the circle to draw a circle so that the circle is tangent to both cutting path 1 and cutting path 2;

[0010] S4. Keep the arc between the two points where the circle is tangent to cutting path 1 and cutting path 2, and remove the other arc parts of the circle, so that the arc is connected to cutting path 1 and cutting path 2 to form a complete corrected cutting path.

[0011] The present invention is used to deal with the overcut phenomenon generated during laser cutting of metal raw materials. Draw a basic graph in the drawing software according to the needle type and size of the probe, and reasonably set process parameters such as the cutting power and cutting speed of the laser according to the required actual thickness of the metal material, and generate the corresponding cutting tool path; judge whether there is an overcut phenomenon after laser cutting at the corner according to the cutting trajectory. If so, proceed to the next step; measure the angle of the corner and the overcut length here, directly connect the two overcut points at the corner, draw the required cutting arc with the longer overcut length as the radius of the circle, and do not retain the redundant part, so that the arc is tangent to the sides of the two corners, realizing a smooth transition, and connecting the arc and the two sides into a line; when the laser cutting trajectory reaches the corner, set the laser cutting speed and cutting power to remain unchanged to complete the cutting at the corner; continue to run with the laser cutting power and cutting speed in the corner area until leaving the corner area, and continue to complete the cutting of the remaining graph.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: It can avoid the overcut phenomenon at the corner in the MEMS probe needle type caused by the irregular laser spot during laser cutting, resulting in energy aggregation, improve the processing efficiency and workpiece quality, and has a low process cost.

[0013] As a further improvement of the present invention, before the step S1, there is also a pre-cutting step S01: Draw a cutting route graph in the drawing software. Draw a basic cutting route graph in the drawing software according to the needle type and size of the probe, and reasonably set process parameters such as the cutting power and cutting speed of the laser according to the required actual thickness of the metal material, and generate the corresponding cutting tool path.

[0014] As a further improvement of the present invention, the drawing software is CAD, and the cutting route graph includes the unit cutting trajectory lines of multiple probes.

[0015] As a further improvement of the present invention, after the pre-cutting step S01, a trial cutting step S02 is further included: first, laser trial cut the unit cutting track line of a probe, and observe through a microscope whether there is over-cut at the corner formed by cutting path 1 and cutting path 2. If there is over-cut, proceed to step S1; if not, perform normal cutting according to the cutting route map. Over-cut means that excessive cutting occurs at the corner formed by two cutting paths, resulting in the laser cutting off more metal raw materials; first, perform trial cutting on a probe, and then observe through a microscope whether there is an over-cut problem. If there is over-cut, make corrections.

[0016] As a further improvement of the present invention, the laser cutting speed and cutting power at the arc, cutting path 1, and cutting path 2 are the same.

[0017] As a further improvement of the present invention, after step S4, laser cut the raw material to be cut according to the corrected cutting path in the drawing software. Cut the raw material using the corrected cutting route.

[0018] As a further improvement of the present invention, cutting path 1 and cutting path 2 are perpendicular to each other. Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the corrected cutting path in the drawing software.

[0020] Figure 2 It is a microscope magnification diagram of the cutting path of the raw material after correction.

[0021] Figure 3 It is a microscope magnification diagram of the cutting path of the raw material during trial cutting.

[0022] Among them, 1 is cutting path 1, and 2 is cutting path 2. Detailed Embodiment

[0023] As Figure 1-2 shown, it is a laser processing method for forming a MEMS probe, including the following steps:

[0024] Pre-cutting step S01: Draw a cutting route map in the drawing software; draw a basic cutting route graph in the drawing software according to the needle type and size of the probe, and reasonably set process parameters such as the cutting power and cutting speed of the laser according to the required thickness of the actual metal material, and generate the corresponding cutting tool path; the drawing software is CAD, and the cutting route map includes the unit cutting track lines of multiple probes;

[0025] Trial cutting step S02: First, laser trial cut the unit cutting track line of a probe. Observe through a microscope whether there is overcut at the corner formed by cutting track 1 and cutting track 2. If there is overcut, perform step S1; if not, perform normal cutting according to the cutting route map. Overcut means that excessive cutting occurs at the corner formed by two cutting tracks, resulting in the laser cutting off more metal raw materials. First, perform trial cutting on a probe, and then observe through a microscope whether there is an overcut problem. If there is overcut, make corrections.

[0026] S1. Measure the angle between cutting track 1 and cutting track 2 on the metal raw material through a microscope, and measure the overcut lengths A and B in the directions of cutting track 1 and cutting track 2 respectively. As Figure 1 shown, A = 4 microns and B = 3 microns.

[0027] S2. Extend cutting track 1 and cutting track 2 in the drawing software and intersect them at a point.

[0028] S3. Judge and compare the values of lengths A and B, and draw a circle with the larger value of lengths A and B as the radius, so that the circle is tangent to both cutting track 1 and cutting track 2.

[0029] S4. Keep the arc between the two points where the circle is tangent to cutting track 1 and cutting track 2, and remove the other arc parts of the circle, so that the arc is connected to cutting track 1 and cutting track 2 to form a complete corrected cutting track.

[0030] After the above step S4, perform laser cutting on the raw material to be cut according to the corrected cutting track in the drawing software. Cut the raw material using the corrected cutting route.

[0031] Cutting track 1 and cutting track 2 are perpendicular to each other.

[0032] The laser cutting speed and cutting power at the arc and at cutting track 1 and cutting track 2 are the same.

[0033] The present invention draws a basic pattern in CAD drawing software according to the needle type and size of the probe. The thickness of the metal raw material required for the MEMS probe is preset to be 40 μm. According to this material thickness, the laser cutting power is set to 0.4 W, the processing speed is set to 10 mm / s, and the cutting tool path is designed according to the corresponding needle type. Due to the spot offset, it is judged from the first cutting trajectory that there is an over-cut phenomenon after the laser cuts at the corner. The over-cut sizes of the X and Y axes are 3 μm and 4 μm respectively, and the shape of the needle body is damaged. Directly connect the two points of the over-cut at the corner, draw an arc to be cut with the 4-μm length of the over-cut on the Y axis as the radius of the circle, and do not retain the extra 1 μm on the X axis, so that the arc is tangent to the sides of the two corners, realizing the smooth transition between the arc and the straight line. Connect the arc and the two straight sides to form a line. When the laser cutting trajectory of the needle body reaches the corner, set the laser cutting speed and cutting power to remain unchanged and complete the cutting here. Continue to run with the laser cutting power and cutting speed in the corner area until leaving the corner area, and continue to complete the cutting of the remaining MEMS probe needle body.

[0034] The present invention has the following advantages: When cutting, there is no need to adjust parameters such as processing speed and cutting power, the needle body part of the probe is not damaged, the operation is simple, it is easier to implement, the processing efficiency is high, and the yield is high (compared with the traditional cutting process, the yield is increased by about 7.6%). The complete needle type is retained, and the electrical performance of the MEMS probe is not affected.

[0035] Figure 2 Microscopic magnification comparison of the corrected raw material cutting path Figure 3 Microscopic magnification of the raw material cutting path during trial cutting, Figure 2 、 Figure 3 The rectangular frame in is the corner of the cutting line, and it can be seen that the over-cut phenomenon is greatly improved.

[0036] The present invention is not limited to the above embodiments. Based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and deformations to some technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A laser processing method for forming a MEMS probe, characterized in that It includes the following steps: Pre-cutting step S01: Draw a cutting route map in a drafting software; the drafting software is CAD, and the cutting route map includes the unit cutting track lines of multiple probes; Trial cutting step S02: First, laser-trial cut the unit cutting track line of a probe, and observe through a microscope whether there is over-cut at the corner composed of cutting lane 1 and cutting lane 2. If there is, proceed to step S1; if not, perform normal cutting according to the cutting route map; S1. Measure the angle between cutting lane 1 and cutting lane 2 on the metal raw material through a microscope, and respectively measure the over-cut lengths A and B in the direction of cutting lane 1 and the direction of cutting lane 2; S2. Extend cutting lane 1 and cutting lane 2 in the drafting software and make them intersect at a point; S3. Judge and compare the values of lengths A and B, and draw a circle with the larger value of lengths A and B as the radius of the circle, so that the circle is tangent to both cutting lane 1 and cutting lane 2; S4. Keep the arc between the two points where the circle is tangent to cutting lane 1 and cutting lane 2, and remove the other arc parts of the circle, so that the arc is connected to cutting lane 1 and cutting lane 2 to form a complete corrected cutting lane; After the step S4, perform laser cutting on the raw material to be cut according to the corrected cutting lane in the drafting software; the laser cutting speed and cutting power at the arc and at cutting lane 1 and cutting lane 2 are the same; cutting lane 1 and cutting lane 2 are perpendicular to each other; the thickness of the metal raw material required for this MEMS probe is set to 40um, and the laser cutting power is set to 0.4w and the processing speed is set to 10mm / s according to this material thickness.

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