MEMS probe forming laser processing method

Abstract

The invention discloses an MEMS probe forming laser processing method in the field of semiconductors, and the method comprises the following steps: S1, measuring an included angle between a cutting channel I and a cutting channel II on a metal raw material through a microscope, and respectively measuring an overcut length A and an overcut length B in the direction of the cutting channel I and the direction of the cutting channel II; s2, the first cutting channel and the second cutting channel are extended and intersect at one point in cartographic software; s3, the value of the length A and the value of the length B are judged and compared, the larger value in the length A and the length B serves as the radius of a circle to draw a circle, and the circle is made to be tangent to the first cutting way and the second cutting way; and S4, an arc between the two points, tangent to the first cutting channel and the second cutting channel, of the circle is reserved, other arc lines of the circle are removed, and the arc is connected with the first cutting channel and the second cutting channel to serve as a complete corrected cutting channel. The corner over-cutting phenomenon during laser cutting is avoided, the machining efficiency and the workpiece quality are improved, and the process cost is low.

Description

Technical Field

[0001] The invention belongs to the field of semiconductors, and in particular relates to a MEMS probe forming laser processing method. Background Art

[0002] Probes are indispensable components in the packaging and testing 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 submicron level. The size and precision requirements of probes are getting higher and higher, and the corresponding structure is becoming more and more complex. In order to adapt to these changes, high-precision femtosecond processing equipment is used to make probes.

[0003] Femtosecond laser cutting technology is a high-precision laser processing technology. Due to its advantages of extremely short pulse width, high peak efficiency and wide spectrum coverage, it has many excellent characteristics in micro-processing and material processing that traditional processes do not have. At the same time, femtosecond laser has an extremely high electric field strength, which is enough 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 field of industrial production is becoming more and more extensive.

[0004] However, when using femtosecond laser cutting to make probes, it is necessary to cut the metal raw materials by laser to process and make the probes; when laser cutting the probes, cutting paths (cutting tracks) will be generated on the raw materials, and corners consisting of two horizontal and vertical cutting paths will often be generated on the raw materials. In the past, when cutting corners, the laser was cut along the horizontal and vertical cutting paths respectively, and it was necessary to cut twice. Due to the special position of the corners, in traditional cutting technology, in order to ensure processing accuracy and cutting stability, when the laser reaches the corner area, the laser cutting speed will be reduced or stopped. At this time, the energy output by the laser will be densely accumulated here, especially the intersection of the horizontal and vertical cutting paths, which is easy to cause over-cutting of the corners during the cutting process, resulting in the output of the 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 MEMS probe forming. In view of the corner overcutting phenomenon existing in the probe forming process, a circular arc transition method is introduced to avoid the corner overcutting phenomenon in the MEMS probe needle shape caused by energy concentration due to the irregular light spot during laser cutting, thereby improving the processing efficiency and workpiece quality, and reducing the process cost.

[0006] The object of the present invention is achieved by: a MEMS probe forming laser processing method, comprising the following steps: S1. Measure the angle between the first cutting path and the second cutting path on the metal raw material through a microscope, and measure the overcut length A and the overcut length B in the direction of the first cutting path and the direction of the second cutting path respectively; S2. In the drawing software, extend cutting path 1 and cutting path 2 and intersect them at one point; S3, judging and comparing the values ​​of length A and length B, taking the larger value of length A and length B as the radius of the circle to draw a circle so that the circle is tangent to both the cutting path 1 and the cutting path 2; S4. The arc between the two points where the circle is tangent to the cutting path 1 and the cutting path 2 is retained, and the other arcs of the circle are removed, so that the arc is connected to the cutting path 1 and the cutting path 2 as a complete corrected cutting path.

[0007] The present invention is used to process the overcutting phenomenon generated when laser cutting metal raw materials. Basic graphics are drawn in the drawing software according to the needle type and size of the probe, and the laser cutting power, cutting speed and other process parameters are reasonably set according to the thickness of the actual metal material required, and a corresponding cutting tool path is generated; it is judged whether there is overcutting after the laser cutting at the corner according to the cutting trajectory, and if so, the next step is carried out; the angle of the corner and the length of the overcut here are measured, and the two overcut points of the corner are directly connected, and the arc required to be cut is drawn with the longer overcut length as the radius of the circle, and the excess part is not retained, so that the arc is tangent to the edges of the two corners, realizing a smooth transition, and connecting the arc and the two edges into a line; when the laser cutting trajectory reaches the corner, the laser cutting speed and cutting power are set to remain unchanged to complete the cutting at the corner; the laser cutting power and cutting speed of the corner area are continued to run until leaving the corner area, and the cutting of the remaining graphics is continued.

[0008] Compared with the prior art, the beneficial effects of the present invention are: it can avoid the overcutting phenomenon of the corners in the MEMS probe needle caused by energy concentration due to irregular light spot during laser cutting, improve processing efficiency and workpiece quality, and have low process cost.

[0009] As a further improvement of the present invention, before the step S1, a pre-cutting step S01 is also included: drawing a cutting route map in a drawing software. A basic cutting route diagram is drawn in the drawing software according to the needle type and size of the probe, and the laser cutting power and cutting speed and other process parameters are reasonably set according to the actual thickness of the required metal material, and a corresponding cutting tool path is generated.

[0010] As a further improvement of the present invention, the drawing software is CAD, and the cutting route map includes unit cutting trajectory lines of multiple probes.

[0011] As a further improvement of the present invention, after the pre-cutting step S01, a trial cutting step S02 is also included: first, laser trial cutting is performed on the unit cutting trajectory of a probe, and the unit cutting trajectory is observed through a microscope to see whether there is overcutting at the corner formed by cutting track 1 and cutting track 2. If so, step S1 is performed; if not, normal cutting is performed according to the cutting road map. Overcutting refers to transitional cutting at the corner formed by two cutting tracks, which causes the laser to cut off more metal raw materials; first, a probe is trial cut, and then a microscope is used to observe whether there is an overcutting problem, and if there is an overcutting problem, correction is performed.

[0012] As a further improvement of the present invention, the laser cutting speed and cutting power at the arc, cutting track 1 and cutting track 2 are the same.

[0013] As a further improvement of the present invention, after step S4, the raw material to be cut is laser cut according to the corrected cutting path in the drawing software. The raw material is cut using the corrected cutting path.

[0014] As a further improvement of the present invention, the first cutting street and the second cutting street are perpendicular to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the corrected cutting path in the mapping software.

[0016] Figure 2 This is a microscope magnified image of the cut path of the raw material after correction.

[0017] Figure 3 This is a microscope magnified image of the cutting path of the raw material during the trial cutting.

[0018] Among them, 1 is cutting lane one, and 2 is cutting lane two. DETAILED DESCRIPTION

[0019] like Figure 1-2 As shown, a MEMS probe forming laser processing method includes the following steps: Pre-cutting step S01: drawing a cutting route map in a drawing software; drawing a basic cutting route diagram in the drawing software according to the needle type and size of the probe, and reasonably setting the laser cutting power and cutting speed and other process parameters according to the actual thickness of the required metal material, and generating a corresponding cutting tool path; the drawing software is CAD, and the cutting route map includes unit cutting trajectory lines of multiple probes; Trial cutting step S02: firstly laser test cutting a unit cutting track line of a probe, and observe through a microscope whether there is overcut at the corner formed by cutting track 1 and cutting track 2 of the unit cutting track line, if yes, then proceed to step S1; if no, then cut normally according to the cutting road map; overcutting refers to transition cutting at the corner formed by two cutting tracks, causing the laser to cut off more metal raw materials; firstly test cutting a probe, and then observe through a microscope whether there is overcutting problem, and if there is overcutting, make corrections; S1. Measure the angle between the cutting path 1 and the cutting path 2 on the metal raw material through a microscope, and measure the overcut length A and the length B in the direction of the cutting path 1 and the direction of the cutting path 2 respectively; Figure 1 In the middle, A = 4 μm, B = 3 μm; S2, in the drawing software, extend the cutting path 1 and the cutting path 2 and intersect them at one point; S3, judging and comparing the values ​​of length A and length B, taking the larger value of length A and length 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; S4, retain the arc between the two points where the circle is tangent to the cutting path 1 and the cutting path 2, and remove the other arcs of the circle, so that the arc is connected to the cutting path 1 and the cutting path 2 as a complete corrected cutting path.

[0020] After step S4, the raw material to be cut is laser cut according to the corrected cutting path in the drawing software. The raw material is cut using the corrected cutting path.

[0021] The cutting path 1 and the cutting path 2 are perpendicular to each other.

[0022] The laser cutting speed and cutting power at the arc, cutting path 1 1 and cutting path 2 2 are the same.

[0023] The present invention draws a basic graphic in a CAD drawing software according to the needle type and size of the probe, presets the thickness of the metal raw material required by the MEMS probe to be 40um, sets the laser cutting power to 0.4w and the processing speed to 10mm / s according to the material thickness, and designs a cutting path according to the corresponding needle type; due to the light spot offset, it is judged according to the first cutting trajectory that the laser has overcutting after cutting at the corner, the overcut sizes of the X and Y axes are 3um and 4um respectively, and the shape of the needle body is damaged; directly connect the two overcut points of the corner, use the 4um length of the Y axis overcut as the radius of the circle to draw the arc required for cutting, and do not retain the excess 1um of the X axis, so that the arc is tangent to the edges of the two corners, realizes a smooth transition between the arc and the straight line, and connects the arc and the two straight line edges into a line; when the laser cutting needle body trajectory 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.

[0024] The present invention has the following advantages: there is no need to adjust parameters such as processing speed and cutting power during cutting, the needle body of the probe is not damaged, the operation is simple, easier to implement, the processing efficiency is high, the yield is high (compared with the traditional cutting process, the yield is increased by about 7.6%), the complete needle shape is retained, and the electrical properties of the MEMS probe are not affected.

[0025] Figure 2 Comparison of microscope magnified images of the raw material cutting path after correction Figure 3 A microscope magnified image of the raw material cutting path during the test cutting. Figure 2 , Figure 3 The middle rectangular box is the corner of the cutting line, and it can be seen that the overcutting phenomenon is greatly improved.

[0026] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A MEMS probe forming laser processing method, characterized in that: The steps include: S1. Measure the angle between the first cutting path and the second cutting path on the metal raw material through a microscope, and measure the overcut length A and the overcut length B in the direction of the first cutting path and the direction of the second cutting path respectively; S2. In the drawing software, extend cutting path 1 and cutting path 2 and intersect them at one point; S3, judging and comparing the values ​​of length A and length B, taking the larger value of length A and length B as the radius of the circle to draw a circle so that the circle is tangent to both the cutting path 1 and the cutting path 2; S4. The arc between the two points where the circle is tangent to the cutting path 1 and the cutting path 2 is retained, and the other arcs of the circle are removed, so that the arc is connected to the cutting path 1 and the cutting path 2 as a complete corrected cutting path.

2. A MEMS probe forming laser processing method according to claim 1, characterized in that: Before the step S1, a pre-cutting step S01 is also included: drawing a cutting route map in a drawing software.

3. A MEMS probe forming laser processing method according to claim 2, characterized in that: The drawing software is CAD, and the cutting route map includes unit cutting trajectory lines of multiple probes.

4. A MEMS probe forming laser processing method according to claim 3, characterized in that: After the pre-cutting step S01, a trial cutting step S02 is also included: first, a unit cutting trajectory line of a probe is laser-cut, and the unit cutting trajectory line is observed through a microscope to see whether there is overcut at the corner formed by cutting path 1 and cutting path 2. If so, step S1 is performed; if not, normal cutting is performed according to the cutting path map.

5. A MEMS probe forming laser processing method according to any one of claims 1 to 4, characterized in that: The laser cutting speed and cutting power at the arc are the same as those at the first cutting path and the second cutting path.

6. A MEMS probe forming laser processing method according to any one of claims 1 to 4, characterized in that: After step S4, the raw material to be cut is laser cut according to the corrected cutting path in the drawing software.

7. A MEMS probe forming laser processing method according to any one of claims 1 to 4, characterized in that: The first cutting path and the second cutting path are perpendicular to each other.

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