Method of processing a semiconductor wafer

Abstract

The processing method of the semiconductor wafer comprises the following steps: using UV glue to stick the front and back surfaces of the semiconductor wafer, forming a first mask on the back surface of the semiconductor wafer, and forming a second mask on the front surface of the semiconductor wafer; sticking the back surface of the semiconductor wafer on a machine table to perform mechanical cutting, cutting to the second mask from the first mask; and using laser to trim the cutting surface of the semiconductor wafer. Through the UV glue mask protection and laser trimming process, the edge collapse rate in the wafer cutting process is significantly reduced, and the processing quality and product yield are improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor processing technology, and more particularly to a method for processing semiconductor wafers. Background Technology

[0002] Currently, semiconductor wafer dicing typically employs mechanical processing methods, involving the grinding and cutting of the wafer using a rotating cutting tool. However, wafers are prone to chipping during the dicing process. Existing technologies usually address this issue by adjusting the blade feed rate and spindle dynamic balance, but the effects are not significant, with chipping rates remaining as high as 10%-15%. Wafer chipping not only affects the appearance quality of the chip but can also lead to performance degradation or even render the chip unusable. Therefore, developing a method to effectively reduce wafer chipping is of significant practical importance. Summary of the Invention

[0003] The purpose of this invention is to provide an improved semiconductor wafer processing method that significantly reduces the chipping rate during wafer dicing and improves processing quality and product yield through UV photomask protection and laser finishing processes.

[0004] To achieve the above objectives, the semiconductor wafer processing method of the present invention includes the following steps:

[0005] UV adhesive is used to attach the front and back sides of the semiconductor wafer, forming a first mask on the back side of the semiconductor wafer and a second mask on the front side of the semiconductor wafer;

[0006] The back side of the semiconductor wafer is bonded to a machine for mechanical dicing, cutting from the first mask to the second mask; and

[0007] The semiconductor wafer is trimmed using a laser.

[0008] Compared with existing technologies, this invention uses UV adhesive to bond the front and back sides of the semiconductor wafer and provides protection with a first and second mask. This effectively protects the wafer from edge chipping during mechanical cutting. Furthermore, combined with laser trimming, it further reduces edge chipping during wafer processing, lowering the chipping rate from 10%-15% in existing technologies to below 0.01%. This significantly improves the processing quality and appearance of the wafer. Moreover, the method of this invention is simple to operate, easily automated, and has high industrial application value. This method is applicable to wafer processing of various materials and thicknesses, exhibiting broad applicability.

[0009] Preferably, the thickness of the first mask and the second mask is 5 mm or more.

[0010] Preferably, the mechanical cutting includes: controlling the spindle speed to be 15000-18000 rpm, the feed rate to be 350-450 rpm, and the blade width to be 0.3-0.55 mm.

[0011] Optionally, the mechanical cutting includes controlling the spindle speed to 15,000, the feed rate to 400 rpm, and the blade width to 0.4 mm.

[0012] Preferably, the adjustment includes: controlling the laser power to be 2-2.5kW, the spot diameter to be 0.1-0.5mm, the defocusing amount to be 10-20mm, and the moving speed to be 10-25mm / s.

[0013] Preferably, the conditioning includes using helium, nitrogen or argon as a protective gas, with a gas flow rate of 30-40 L / min. Detailed Implementation

[0014] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific implementation methods of this application are described in detail below with reference to some embodiments. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0015] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0016] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0017] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0018] The semiconductor wafer processing method of the present invention will be further described below with reference to embodiments, but this does not limit the present invention. The method of the present invention aims to provide an improved semiconductor wafer processing method, which significantly reduces the chipping rate during wafer dicing and improves processing quality and product yield through UV adhesive, mask protection and laser finishing processes.

[0019] In one embodiment of the semiconductor wafer processing method of the present invention, the following steps are included:

[0020] UV adhesive is used to attach the front and back sides of the semiconductor wafer, and a first mask is covered on the back side of the semiconductor wafer, and a second mask is covered on the front side of the semiconductor wafer.

[0021] The back side of the semiconductor wafer is bonded to a machine for mechanical dicing, cutting from the first mask to the second mask; and

[0022] The semiconductor wafer is trimmed using a laser.

[0023] This invention uses UV adhesive to bond the front and back sides of a semiconductor wafer and provides protection with a first and second mask. This effectively protects the wafer from edge chipping during mechanical dicing. Furthermore, combined with laser trimming, it further reduces edge chipping during wafer processing, lowering the chipping rate from 10%-15% in existing technologies to below 0.01%. This significantly improves the processing quality and appearance of the wafer. Moreover, the method of this invention is simple to operate, easily automated, and has high industrial application value. This method is applicable to wafer processing of various materials and thicknesses, exhibiting broad applicability.

[0024] In a specific embodiment, UV adhesive is used for bonding and mask fabrication. First, UV adhesive is used to bond the front and back sides of the wafer, and then a mask is fabricated using exposure and development methods to form a protective layer, while preventing chip misalignment caused by separation after processing. Specifically, a first mask is applied to the back side of the semiconductor wafer, and a second mask is applied to the front side of the semiconductor wafer. Preferably, the thickness of the first and second masks is 5 mm or more.

[0025] Optionally, in other embodiments, the UV adhesive formulation can be adjusted to improve its adhesion and flexibility, thereby better absorbing the vibration forces generated during the dicing process. Additionally, the mask thickness can be optimized based on the wafer thickness and material properties to further enhance the protective effect. For example, for thicker wafers, the mask thickness can be appropriately increased. Preferably, high-precision photolithography is employed during the mask exposure and development processes to improve the mask's accuracy and uniformity.

[0026] Specifically, in the machining process, the back side of the wafer is bonded to the machine tool for cutting. Preferably, the spindle speed is controlled at 15000-18000 rpm, the feed rate at 350-450 rpm, and the blade width at 0.3-0.55 mm. The blade first cuts into the first mask, then continues to penetrate deeper into the wafer, and finally into the second mask until it is completely cut off. By penetrating deeper into the cutting position, the UV adhesive-formed mask absorbs and mitigates the vibration force generated during the cutting process, and finally passes through the second mask again before cutting off, thus playing a shock-absorbing role. Measurements show that the edge chipping rate of semiconductors processed using the method of this invention is only 0.1%, while the chipping rate in the prior art is 10%-15%. After cutting, the long strip-shaped cross-section of the semiconductor is sandwiched in the middle by UV adhesive.

[0027] Specifically, selecting suitable tool materials for wafer dicing, such as supercarbide or diamond tools, and optimizing the tool shape and cutting edge design can reduce stress concentration during the cutting process. Ideally, in mechanical cutting, the spindle and feed rates should be dynamically adjusted, and an intelligent control system should be developed to dynamically adjust the spindle speed and feed rate based on the actual wafer processing conditions to further reduce the risk of edge chipping. During cutting, sudden changes in tool direction or pauses on the wafer surface should be avoided to reduce the possibility of edge chipping.

[0028] In a preferred embodiment, the laser power is controlled to be 2-2.5kW, the spot diameter is 0.1-0.5mm, the defocusing amount is 10-20mm, and the moving speed is 10-25mm / s.

[0029] Specifically, after mechanical cutting, a laser is used to trim the cut surface of the semiconductor wafer. Specifically, the laser power is controlled at 2-2.5kW, the spot diameter at 0.1-0.5mm, the defocusing amount at 10-20mm, the moving speed at 10-25mm / s, and the protective gas is helium, nitrogen, or argon at a flow rate of 30-40L / min. Laser trimming softens the wafer's cut surface, repairs chipped edges, reduces the number and size of chipped edges, thereby achieving higher processing quality.

[0030] In a preferred embodiment, a 5mm thick UV adhesive is used to adhere the front and back sides of the wafer. A mask with a thickness of 5mm is created through exposure and development processes. The back side of the wafer is then bonded to the machine, with the spindle speed set to 15000 rpm, the feed rate to 400 rpm, and the blade width to 0.4mm. The blade first cuts into the first mask, then into the wafer, and finally into the second mask until a complete cut is achieved. Measurements show that the semiconductor edge chipping rate is only 0.1%. Next, a laser with a power of 2kW, a spot diameter of 0.3mm, a defocusing amount of 10mm, a movement speed of 10mm / s, and helium as the protective gas with a flow rate of 30L / min is used. After laser trimming, the wafer edge chipping size is reduced to below 2 micrometers, with a chipping rate of only 0.01%.

[0031] In another preferred embodiment, a 6mm thick UV adhesive is used to adhere to both sides of the wafer. A mask with a thickness of 6mm is created through exposure and development processes. The back side of the wafer is attached to the machine, with the spindle speed set to 18000 rpm, the feed rate to 350 rpm, and the blade width to 0.3mm. The blade first cuts into the first mask, then into the wafer, and finally into the bottom mask until completely cut. Measurements show that the semiconductor edge chipping rate is only 0.08%. Next, a laser with a power of 2.5kW, a spot diameter of 0.5mm, a defocusing amount of 20mm, a movement speed of 20mm / s, and nitrogen as the protective gas at a flow rate of 35L / min is used. After laser trimming, the wafer chipping size is reduced to below 1.5 micrometers, with a chipping rate of only 0.008%.

[0032] In another preferred embodiment, a 7mm thick UV adhesive is used to adhere to both sides of the wafer. A mask with a thickness of 7mm is then created through exposure and development processes. The back side of the wafer is attached to the machine, with the spindle speed set to 16000 rpm, the feed rate to 450 rpm, and the blade width to 0.55mm. The blade first cuts into the first mask, then into the wafer, and finally into the bottom mask until completely cut. Measurements show that the semiconductor edge chipping rate is only 0.05%. Next, a laser with a power of 2.5kW, a spot diameter of 0.5mm, a defocusing amount of 10mm, a movement speed of 25mm / s, and argon as the protective gas at a flow rate of 40L / min is used. After laser trimming, the wafer edge chipping size is reduced to below 1.5 micrometers, with a chipping rate of only 0.005%.

[0033] In summary, this invention uses UV adhesive to bond the front and back sides of a semiconductor wafer and provides protection with a first and second mask. This effectively protects the wafer from edge chipping during mechanical dicing. Furthermore, combined with laser trimming, it further reduces edge chipping during wafer processing, lowering the chipping rate from 10%-15% in existing technologies to below 0.01%. This significantly improves the processing quality and appearance of the wafer. Moreover, the method of this invention is simple to operate, easily automated, and has high industrial application value. This method is applicable to wafer processing of various materials and thicknesses, exhibiting broad applicability.

[0034] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A method for processing semiconductor wafers, characterized in that, Includes the following steps: UV adhesive is used to attach the front and back sides of the semiconductor wafer, forming a first mask on the back side of the semiconductor wafer and a second mask on the front side of the semiconductor wafer; The back side of the semiconductor wafer is bonded to the machine for mechanical cutting, from the first mask to the second mask; as well as The semiconductor wafer is trimmed using a laser.

2. The semiconductor wafer processing method as described in claim 1, characterized in that, The thickness of the first mask and the second mask is 5 mm or more.

3. The semiconductor wafer processing method as described in claim 1, characterized in that, The mechanical cutting includes controlling the spindle speed to 15000-18000 rpm, the feed rate to 350-450 rpm, and the blade width to 0.3-0.55 mm.

4. The semiconductor wafer processing method as described in claim 1, characterized in that, The mechanical cutting includes controlling the spindle speed to 15,000, the feed rate to 400 rpm, and the tool width to 0.4 mm.

5. The semiconductor wafer processing method as described in claim 1, characterized in that, The adjustment includes: controlling the laser power to be 2-2.5kW, the spot diameter to be 0.1-0.5mm, the defocusing amount to be 10-20mm, and the moving speed to be 10-25mm / s.

6. The semiconductor wafer processing method as described in claim 1, characterized in that: The conditioning process includes using helium, nitrogen, or argon as a protective gas with a flow rate of 30-40 L / min.