CN111451646A - A processing technology of wafer laser stealth cutting - Google Patents

Abstract

The invention relates to a processing technology for laser stealth cutting of wafers, comprising the following steps: Step 1: put the incoming wafer without film on the laser processing equipment, and put the back side on the processing platform for vacuum adsorption; step 2: pass the laser processing equipment Laser grooving is performed on the front side of the wafer, and after grooving, the front side of the wafer is pasted with BG film, step 3: put it into the grinding equipment for back grinding to thin the wafer to a preset thickness; step 4: Put the wafer into the laser stealth cutting machine, place the front side of the wafer on the processing platform for vacuum adsorption, and then perform alignment processing through the infrared camera in the laser stealth cutting machine; Step 5: After the laser stealth cutting, place the wafer on the back of the wafer. Paste the UV film and stick it on the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. The wafer is removed and the BG film on the front is torn off. The circular film expansion process divides the diced wafer into independent dies. The present invention can improve work efficiency.

Description

A processing technology of wafer laser stealth cutting

technical field

The invention belongs to the technical field of semiconductor packaging, and in particular relates to a processing technology for laser stealth cutting of wafers.

Background technique

With the improvement of the functional structure of the wafer, the front side of the wafer is more and more sensitive to light and dust, so the time that the front side of the wafer is exposed during the wafer processing process is minimized. The current electronic components are cut with diamond grinding wheel blades. During the entire processing process, the front side of the wafer is exposed in the air, and the speed is slow.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the purpose of the present invention is to provide a processing technology for laser stealth cutting of wafers.

To achieve the above object, the present invention adopts the following technical solutions:

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the laser processing equipment, and place the back on the processing platform for vacuum adsorption;

Step 2: Laser grooving is performed on the front side of the wafer by laser processing equipment, and BG film is attached to the front side of the wafer after grooving;

Step 3: After the film is slotted in Step 2, put it into the grinding equipment for back grinding to thin the wafer to the preset thickness;

Step 4: After completing the preset thickness in step 3, put the wafer into the laser stealth cutting machine, place the wafer front side down on the processing platform for vacuum adsorption, and then perform alignment processing by the infrared camera in the laser stealth cutting machine;

Step 5: After the laser stealth cutting, paste the UV film on the back of the wafer and paste it on the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. Remove and tear off the BG film on the front side, and then expand the wafer, and divide the cut wafer into independent dies.

Preferably, in the processing technology of the laser stealth cutting of wafers, the alignment processing in the step 4 refers to the processing corresponding to the grooves on the back side of the wafer and the front side of the wafer.

Preferably, in the processing technology for laser stealth cutting of wafers, in step 1, the groove depth of the wafer is less than or equal to 20um, and the groove width is less than or equal to 160um.

Preferably, in the processing technology for laser stealth cutting of wafers, the preset thickness in step 3 is ≤800um.

Preferably, in the processing technology for laser stealth cutting of wafers, in step 5, the wafer is expanded on a membrane expansion device.

Preferably, in the processing technology for laser stealth cutting of wafers, an ultraviolet nanosecond laser is used for grooving the wafer, wherein, when the frequency of the ultraviolet nanosecond laser is 40KHZ, the power is greater than 13W, the pulse width is 90±30NS, and the frequency is 200KHZ When the power is greater than 4W, the pulse width is 210±30NS.

Preferably, in the processing technology for laser stealth cutting of wafers, the ultraviolet nanosecond laser can perform shaping processing on the wafer, and the shaping processing method is as follows. It is divided into two paths of light, one for trimming and the other for grooving. After trimming, the beam splitter driven by the motor is divided into two paths of light whose width can be changed. For the light spot, the focal length of the two cylindrical lenses must satisfy 1≤plano-convex/plano-concave≤3. When processing the wafer, according to the actual processing width of the product, first trim the edges to draw two safety lines, and the width is the actual processing width of the product. Then use the groove to remove the middle area of the two safety lines.

Preferably, in the processing technology for laser stealth cutting of wafers, in the step 4, the laser stealth cutting machine is an infrared nanosecond laser, wherein the frequency is 50-100KHZ, the power is greater than 4W when the frequency is 100KHZ, and the pulse width is 100± 30NS, combined with the infrared camera to see the front pattern of the wafer through the light transmission on the back of the wafer, and grab the feature points for alignment processing.

By means of the above scheme, the present invention has at least the following advantages:

1. The present invention can reduce the contamination of the front surface of the wafer by external light and dust. The wafer is from a complete thick sheet to a single thinned standard die, and the front surface of the wafer is exposed to the air for the least time.

2. Improve production efficiency. Traditional wafer processing uses diamond grinding wheel blades to cut, and the slow speed is only 50mm/s, while the laser processing speed can reach 300mm/s, which is 6 times that of traditional processing.

3. The traditional diamond grinding wheel blade is a consumable item. The annual cost of purchasing a diamond grinding wheel blade is about 400,000 yuan, while the laser processing equipment has no consumables.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, and to implement according to the content of the description, the preferred embodiments of the present invention are described in detail below.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

It is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top" , "bottom", "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship, only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, construction and operation in a particular orientation, and therefore should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first" or "second" may expressly or implicitly include one or more of that feature. In the description of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

Example

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the laser processing equipment, and place the back on the processing platform for vacuum adsorption;

Step 2: Laser grooving is performed on the front side of the wafer by laser processing equipment, and BG film is attached to the front side of the wafer after grooving.

Step 3: After the film is slotted in Step 2, put it into the grinding equipment for back grinding to thin the wafer to the preset thickness;

Step 4: After completing the preset thickness in step 3, put the wafer into the laser stealth cutting machine, place the wafer front side down on the processing platform for vacuum adsorption, and then perform alignment processing by the infrared camera in the laser stealth cutting machine;

Step 5: After the laser stealth cutting, paste the UV film on the back of the wafer and paste it on the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. Remove and tear off the BG film on the front side, and then expand the wafer, and divide the cut wafer into independent dies.

In the present invention, the alignment process in step 4 refers to the process in which the back surface of the wafer corresponds to the grooves on the front surface of the wafer. Among them, the laser stealth cutting machine is an infrared nanosecond laser, and the frequency of the infrared nanosecond laser is 50-100KHZ. When the frequency is 100KHZ, the power is greater than 4W, and the pulse width is 100±30NS. Combined with the infrared camera, the back of the wafer can see the front of the wafer. Graphics, grab feature points for alignment processing.

Example 1

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the UV nanosecond laser processing platform, and place the back on the processing platform for vacuum adsorption;

Step 2: Draw two safety lines with a frequency of 200KHZ by an ultraviolet nanosecond laser, and then perform laser groove processing on the front side of the wafer with a frequency of 40KHZ. The groove depth of the wafer is 20um, and the groove width is 160um , At the same time, the optical path of the equipment is shaped. The laser emitted by the ultraviolet nanosecond laser is first divided into two and becomes two paths of light, one for trimming and the other for grooving. Two-way light with variable width, the groove is shaped into an elliptical spot by two plano-convex and plano-convex cylindrical lenses. The focal length of the two cylindrical lenses must satisfy 1≤plano-convex/plano-concave≤3. When processing wafers According to the actual processing width of the product, first trim the edges and draw two safety lines, the width of which is the actual processing width of the product, and then remove the middle area of the two safety lines with grooving.

Step 3: After the film is slotted in Step 2, put it into the grinding equipment for back grinding, so that the wafer is thinned to a preset thickness, up to 800um;

Step 4: After completing the preset thickness in step 3, put the wafer on the infrared nanosecond laser processing platform, place the wafer on the processing platform with the front side facing down, vacuum adsorption, and then pass the infrared camera in the infrared nanosecond laser processing platform perform alignment processing;

Step 5: After the infrared nanosecond laser is cut at 100KHZ, the UV film is attached to the back of the wafer and attached to the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. Next, the wafer is removed and the BG film on the front side is torn off, and then the wafer is expanded by a film expansion device, and the cut wafer is divided into independent dies.

Embodiment 2

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the UV nanosecond laser processing platform, and place the back on the processing platform for vacuum adsorption;

Step 2: Draw two safety lines with a frequency of 200KHZ by an ultraviolet nanosecond laser, and then groove with a frequency of 40KHZ, and perform laser groove processing on the front side of the wafer. The groove depth of the wafer is 10um. The width is 100um, and BG film is attached to the front of the wafer after slotting;

Step 3: After the film is slotted in step 2, put it into the grinding equipment for back grinding, so that the wafer is thinned to a preset thickness, up to 500um;

Step 4: After completing the preset thickness in step 3, put the wafer on the infrared nanosecond laser processing platform, place the wafer on the processing platform with the front side facing down, vacuum adsorption, and then pass the infrared camera in the infrared nanosecond laser processing platform perform alignment processing;

Step 5: After the infrared nanosecond laser is cut at 80KHZ and the frequency is 90KHZ, the UV film is attached to the back of the wafer and attached to the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. Then, the wafer is removed and the BG film on the front side is torn off, and then the wafer is expanded by a film expansion device, and the cut wafer is divided into independent dies.

Embodiment 3

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the UV nanosecond laser processing platform, and place the back on the processing platform for vacuum adsorption;

Step 2: Draw two safety lines with a frequency of 200KHZ by an ultraviolet nanosecond laser, and then perform laser groove processing on the front side of the wafer with a frequency of 40KHZ. The groove depth of the wafer is 15um, and the groove width is 140um , after grooving, paste the BG film on the front of the wafer;

Step 3: After the film is slotted in step 2, put it into the grinding equipment for back grinding, so that the wafer is thinned to a preset thickness, up to 600um;

Step 4: After completing the preset thickness in step 3, put the wafer on the infrared nanosecond laser processing platform, place the wafer on the processing platform with the front side facing down, vacuum adsorption, and then pass the infrared camera in the infrared nanosecond laser processing platform perform alignment processing;

Step 5: Infrared nanosecond laser at 90KHZ, after cutting, paste UV film on the back of the wafer and paste it on the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. , then remove the wafer and tear off the BG film on the front side, and then use the film expansion equipment to perform film expansion processing on the wafer, and divide the cut wafer into independent dies.

Embodiment 4

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the UV nanosecond laser processing platform, and place the back on the processing platform for vacuum adsorption;

Step 2: Draw two safety lines with a frequency of 200KHZ by an ultraviolet nanosecond laser, and then perform laser groove processing on the front side of the wafer with a frequency of 40KHZ. The groove depth of the wafer is 9um, and the groove width is 90um , after grooving, paste the BG film on the front of the wafer;

Step 3: After the film is slotted in step 2, put it into the grinding equipment for back grinding, so that the wafer is thinned to the preset thickness, up to 400um;

Step 4: After completing the preset thickness in step 3, put the wafer on the infrared nanosecond laser processing platform, place the wafer on the processing platform with the front side facing down, vacuum adsorption, and then pass the infrared camera in the infrared nanosecond laser processing platform perform alignment processing;

Step 5: Infrared nanosecond laser at 70KHZ, after cutting, paste UV film on the back of the wafer and paste it on the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. , then remove the wafer and tear off the BG film on the front side, and then use the film expansion equipment to perform film expansion processing on the wafer, and divide the cut wafer into independent dies.

Embodiment 5

A processing technology of wafer laser stealth cutting, comprising the following steps:

Step 1: Put the future wafer without film on the UV nanosecond laser processing platform, and place the back on the processing platform for vacuum adsorption;

Step 2: Draw two safety lines with a frequency of 200KHZ by an ultraviolet nanosecond laser, and then perform laser groove processing on the front side of the wafer with a frequency of 40KHZ. The groove depth of the wafer is 5um, and the groove width is 50um , after grooving, paste the BG film on the front of the wafer;

Step 3: After the film is slotted in step 2, put it into the grinding equipment for back grinding, so that the wafer is thinned to the preset thickness, up to 200um;

Step 4: After completing the preset thickness in step 3, put the wafer on the infrared nanosecond laser processing platform, place the wafer on the processing platform with the front side facing down, vacuum adsorption, and then pass the infrared camera in the infrared nanosecond laser processing platform perform alignment processing;

Step 5: Infrared nanosecond laser at 50KHZ, after cutting, paste UV film on the back of the wafer and paste it on the steel ring. At this time, the front of the wafer is attached to the BG film, and the back of the wafer is attached to the UV film with the steel ring. , then remove the wafer and tear off the BG film on the front side, and then use the film expansion equipment to perform film expansion processing on the wafer, and divide the cut wafer into independent dies.

In the above-mentioned Embodiments 2 to 5, the wafer needs to be shaped. The laser emitted by the ultraviolet nanosecond laser is first divided into two and becomes two paths of light, one for trimming, and one for grooving, repairing The beam splitter driven by the motor is then divided into two beams of variable width, and the groove is shaped into an elliptical spot by two cylindrical lenses, plano-concave and plano-convex. The focal length of the two cylindrical lenses must satisfy 1≤flat. Convex/plano-concave≤3. When processing wafers, according to the actual processing width of the product, first trim the edges and draw two safety lines, the width is the actual processing width of the product, and then use the groove to remove the middle area of the two safety lines. Then, the front side of the wafer is pasted with BG film;

The vacuum adsorption device for wafer adsorption mentioned in the present invention is a technology known to those skilled in the art, and will not be repeated here.

The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. It should be pointed out that for those skilled in the art, some improvements can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (8)

1. A processing technology for laser invisible cutting of a wafer is characterized by comprising the following steps:

step 1: placing the incoming wafer on laser processing equipment without film sticking, and placing the back of the incoming wafer on a processing platform for vacuum adsorption;

step 2: performing laser grooving treatment on the front surface of the wafer through laser processing equipment, and attaching a BG film to the front surface of the wafer after grooving;

and step 3: after the groove is opened and the film is pasted in the step 2, the film is placed into grinding equipment for back grinding, and the wafer is thinned to a preset thickness;

and 4, step 4: after the preset thickness is finished in the step 3, putting the wafer into a laser invisible cutting machine, putting the front side of the wafer downwards on a processing platform for vacuum adsorption, and then carrying out alignment processing through an infrared camera in the laser invisible cutting machine;

and 5: after laser invisible cutting, a UV film is pasted on the back of the wafer and is pasted on the steel ring, the BG film is pasted on the front of the wafer, the back of the wafer is pasted on the UV film with the steel ring, then the wafer is taken down and the BG film on the front is torn off, then the wafer is subjected to film expansion treatment, and the wafer after cutting is divided into independent crystal grains.

2. The process for processing the laser invisible cutting of the wafer as claimed in claim 1, wherein: the alignment processing in the step 4 refers to processing of the back surface of the wafer and the front surface of the wafer corresponding to the groove.

3. The process for processing the laser invisible cutting of the wafer as claimed in claim 1, wherein: in the step 1, the slotting depth of the wafer is less than or equal to 20um, and the slotting width is less than or equal to 160 um.

4. The process for processing the laser invisible cutting of the wafer as claimed in claim 1, wherein: the thickness preset in the step 3 is less than or equal to 800 um.

5. The process for processing the laser invisible cutting of the wafer as claimed in claim 1, wherein: and in the step 5, the wafer is subjected to film expansion on film expansion equipment.

6. The process for processing the laser invisible cutting of the wafer as claimed in claim 1, wherein: the wafer slotting adopts an ultraviolet nanosecond laser, wherein the power of the ultraviolet nanosecond laser is larger than 13W when the frequency is 40KHZ, the pulse width is 90 +/-30 NS, the power of the ultraviolet nanosecond laser is larger than 4W when the frequency is 200KHZ, and the pulse width is 210 +/-30 NS.

7. The process for processing the laser invisible cutting of the wafer as claimed in claim 6, wherein: the ultraviolet nanosecond laser can be used for shaping a wafer, the shaping method is as follows, laser emitted by the ultraviolet nanosecond laser is divided into two paths of light, one path of light is used for trimming, the other path of light is used for grooving, the trimming is divided into two paths of light with changeable width through a spectroscope driven by a motor, the grooving is shaped into an elliptical light spot through two plano-concave and plano-convex cylindrical lenses, the focal length of the two cylindrical lenses is required to meet that plano-convex/plano-concave is not more than 1 and not more than 3, two safety lines are firstly trimmed and drawn out according to the actual processing width of a product when the wafer is processed, the width is the actual processing width of the product, and then the middle area of the two safety lines is completely removed through the grooving.

8. The process for processing the laser invisible cutting of the wafer as claimed in claim 1, wherein: and 4, the laser invisible cutting machine in the step 4 is an infrared nanosecond laser, wherein the frequency is 50-100KHZ, the power is greater than 4W when the frequency is 100KHZ, the pulse width is 100 +/-30 NS, the front side graph of the wafer is seen through the light transmission of the back side of the wafer by combining an infrared camera, and the characteristic points are grabbed for alignment processing.