Glass carrier for wafer temporary bonding and wafer temporary bonding method
By using a glass carrier with annular protrusions and grooves during wafer spin coating, the problem of uneven wafer thickness was solved, the thickness difference and mechanical strength of the wafer surface were optimized, and the stability and reliability of subsequent processes were ensured.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHENGDU HAIGUANG MICROELECTRONICS TECH CO LTD
- Filing Date
- 2026-03-18
- Publication Date
- 2026-06-23
AI Technical Summary
In the prior art, the formation of thick adhesive areas due to centrifugal force during the spin coating of bonding adhesive on wafers leads to uneven wafer thickness, affecting the uniformity of subsequent processes, and may cause bonding voids or delamination, reducing mechanical strength.
A glass carrier with an uneven bonding surface is used, and annular protrusions and grooves are set to compensate for the thick adhesive area. The total thickness difference of the wafer surface is optimized by the design of annular protrusions and grooves to control warping, and the local pressure and flow conduction effect are enhanced by the micro-protrusion structure.
It effectively reduces the total thickness difference on the wafer surface, avoids bonding voids or delamination, improves mechanical strength, and ensures the uniformity and reliability of subsequent processes.
Smart Images
Figure CN122270098A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor packaging technology, and more particularly to a glass carrier for temporary wafer bonding and a temporary wafer bonding method. Background Technology
[0002] 2.5D packaging integrates multi-chip three-dimensional interconnects through an interposer, the core of which lies in the application of TSV (Through Silicon Via) technology. Since the depth of a TSV is usually smaller than the thickness of the interposer wafer it is embedded in, to achieve the interconnection, a thinning process must be performed on the back side of the interposer wafer to expose the conductive copper pillars of the TSV.
[0003] In 2.5D packaging, the commonly used TSV exposure processes are BFR (Backside-flat reveal) and BVR (Backside-via reveal). Temporary bonding (TB) is a critical step in the BFR / BVR process, and its quality directly affects the yield of subsequent TSV exposure, chemical mechanical polishing (CMP), and wafer thinning. Temporary bonding mainly includes the following steps: spin-coating bonding adhesive onto the interposer wafer—pre-baking and curing (pre-baking removes solvent, and step-curing allows the polymer adhesive to polymerize)—alignment and pre-bonding (aligning and pre-bonding the interposer wafer with the carrier)—bonding and lamination.
[0004] Existing temporary bonding techniques have the following problems:
[0005] During spin-coating of bonding adhesive, the centrifugal force generated by the high-speed rotation of the wafer forces the adhesive to diffuse outward from the center. When the adhesive reaches the wafer edge, due to abrupt changes in the interfacial tension between the wafer and air (such as changes in contact angle), the adhesive cannot be completely ejected, leading to accumulation at the edge and forming a thick adhesive region. This thick adhesive region causes uneven overall wafer thickness, resulting in excessive TTV (Total Thickness Variation), which affects the uniformity of subsequent wafer thinning and CMP processes. Furthermore, the thick adhesive region is prone to causing bonding voids or delamination, reducing mechanical strength. Summary of the Invention
[0006] In view of this, the present invention provides a glass carrier for temporary bonding of wafers and a temporary bonding method for wafers, which can compensate for the thick adhesive area of the wafer, optimize the total thickness difference of the wafer, and avoid bonding voids or delamination caused by excessive adhesive thickness at the edges.
[0007] In a first aspect, the present invention provides a glass carrier for temporary bonding of wafers, the glass carrier having a bonding surface, the bonding surface being an uneven surface, wherein... On the bonding surface, an annular protrusion is provided at a first distance from the edge of the glass carrier, and an annular groove is provided at a second distance from the edge of the glass carrier, wherein the first distance is smaller than the second distance; The annular groove is directly opposite the thick adhesive area of the wafer; Both the annular protrusion and the annular groove have arc-shaped cross-sections.
[0008] Optionally, the depth of the annular groove is between 0 and 100 μm, and the width is between 1 and 3 mm.
[0009] Optionally, the center height of the annular protrusion is between 0 and 50 μm, and the radius of curvature of the annular protrusion is between 100 and 300 mm.
[0010] Optionally, periodic first micro-protrusions are provided in the annular groove to break the continuous flow of bonding adhesive, thereby inhibiting the formation of thick adhesive regions on the wafer.
[0011] Optionally, the height of the first microprotrusion is between 1 and 5 μm.
[0012] Optionally, a second micro-protrusion is provided on the bonding surface, the second micro-protrusion being directly opposite the dicing area of the wafer, to enhance local pressure and suppress the generation of bubbles in the dicing area of the wafer.
[0013] Optionally, the cross-sectional shape of the second micro-protrusion is arc-shaped, the center height is between 1 and 10 μm, and the radius of curvature of the second micro-protrusion is between 50 and 200 μm.
[0014] Optionally, the bonding surface is provided with a plurality of radially distributed third micro-protrusions to guide the bonding adhesive.
[0015] Optionally, the height of the third micro-protrusion is less than 3 μm, and it is teardrop-shaped or cylindrical.
[0016] Optionally, the coefficient of thermal expansion of the glass carrier is between 3 and 5 ppm / ℃, and the thickness is between 600 and 850 μm.
[0017] In a second aspect, the present invention provides a method for temporary bonding of wafers, the method comprising: Spin-coating bonding adhesive onto the bonding surface of the wafer and then baking it; The baked wafer and the glass carrier are aligned. The glass carrier is the one provided in the first aspect, and the glass carrier has been spin-coated with a release layer. The wafer and the glass substrate are temporarily bonded by heating and pressurizing in a sealed vacuum chamber.
[0018] The present invention provides a glass carrier and a method for temporary wafer bonding. The bonding surface has an annular groove directly opposite the thick adhesive area of the wafer. This groove compensates for the thick adhesive area, actively counteracting the tendency for adhesive accumulation at the wafer edges, optimizing the total thickness variation (TTV) of the wafer surface, and controlling wafer warpage. An annular protrusion is located near the edge of the glass carrier, which reduces the thickness of the outermost bonding adhesive, optimizing the problem of voids or delamination at the bonding edge and improving mechanical strength. Furthermore, the annular protrusion allows the adhesive to flow more effectively into the annular groove. Attached Figure Description
[0019] Figure 1 This is a top view of a glass carrier used for temporary wafer bonding in one embodiment of the present invention. Figure 2 This is a partially magnified side view of a glass carrier used for temporary wafer bonding in one embodiment of the present invention. Figure 3 This is a schematic flowchart of a temporary wafer bonding method in one embodiment of the present invention.
[0020] Explanation of reference numerals in the attached figures 10: Glass substrate 100: Bonding surface 101: Annular protrusion 102: Annular groove 104: Second micro-protrusion 105: Third micro-protrusion Detailed Implementation To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts of this disclosure.
[0021] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.
[0022] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0023] This invention provides a glass carrier 10 for temporary wafer bonding, with reference to... Figure 1 and Figure 2 , Figure 1 This is an overall view of the glass carrier 10 from top view. Figure 2 This is a magnified view of a partial detail in a cross-sectional view of the glass carrier 10. The glass carrier 10 has a bonding surface 100, which is an uneven surface. An annular protrusion 101 is provided on the bonding surface 100 at a first distance from the edge of the glass carrier 10, and an annular groove 102 is provided at a second distance from the edge of the glass carrier 10. The first distance is smaller than the second distance, that is, the annular protrusion 101 is closer to the edge than the annular groove 102. The annular groove 102 is directly opposite the thick adhesive area of the wafer; Both the annular protrusion 101 and the annular groove 102 have arc-shaped cross-sections.
[0024] It should be noted that the first distance between the annular protrusion 101 and the edge of the glass carrier 10 refers to the distance between the center height of the annular protrusion 101 and the edge of the glass carrier 10. The annular protrusion 101 surrounds the bonding surface 100 of the glass carrier. The second distance between the annular groove 102 and the edge of the glass carrier 10 refers to the distance between the center position of the annular groove 102 and the edge of the glass carrier 10. The annular groove 102 surrounds the bonding surface 100 of the glass carrier. The cross-section of the annular protrusion 101 and the annular groove 102 refers to a plane perpendicular to the bonding surface 100 of the glass carrier.
[0025] As an optional implementation, the coefficient of thermal expansion (CTE) of the glass substrate 10 is between 3 and 5 ppm / ℃, and the thickness is between 600 and 850 μm. The diameter of the glass substrate 10 can be, for example, 300 mm.
[0026] The center height of the annular protrusion 101 is between 0 and 50 μm, the first distance between it and the edge of the glass carrier is between 1 and 3 mm, and the radius of curvature of the annular protrusion 101 is between 100 and 300 mm. The center height of the annular protrusion 101 is on the order of micrometers, the width is on the order of millimeters, and the corresponding radius of curvature is on the order of millimeters. The cross-section of the annular protrusion 101 can be understood as a very small arc on a millimeter-scale great circle. The annular protrusion 101 may or may not be in direct contact with the edge of the annular groove 102. It is understood that when the edges of the annular protrusion 101 and the annular groove 102 are not in contact, the edges of the annular protrusion 101 and the annular groove 102 are connected through a flat surface portion of the glass carrier (the surface of the glass carrier, apart from the designed annular protrusion and annular groove, is flat).
[0027] The annular protrusion 101 reduces the thickness of the outermost bonding adhesive, avoiding bonding voids or delamination caused by excessively thick adhesive at the edges, thus improving mechanical strength. Additionally, the annular protrusion 101 reduces the risk of air bubbles caused by moisture absorption from the thick outer adhesive, providing physical support for safe wafer production under subsequent humid, hot, and pressure environments. The annular protrusion 101 also facilitates better flow of the adhesive into the annular groove 102.
[0028] The depth of the annular groove 102 can be between 0 and 100 μm, and the width between 1 and 3 mm. The second distance between the groove and the edge of the glass carrier 10 depends on the distribution of the thick adhesive area on the wafer. It is understood that the depth of the annular groove 102 refers to the depth at the center, and the width refers to the distance between the two edges. In practical designs, the thick adhesive area on the wafer is a region that can be determined through extensive testing; this thick adhesive area is located on the outer edge of the wafer. Knowing the location of the thick adhesive area, the annular groove 102 can be set at the corresponding position on the bonding surface 100 of the glass carrier to compensate for the thick adhesive area, actively counteract the tendency of adhesive accumulation at the edges, optimize the total thickness variation (TTV) on the wafer surface, and control wafer warpage. Experimental data shows that the TTV is typically greater than 5 μm before optimization, and can be reduced to less than 5 μm after optimization. In one embodiment, for example, the second distance between the annular groove 102 and the edge of the glass carrier can be between 2 and 10 mm.
[0029] The aforementioned glass carrier has an annular groove on its bonding surface that directly faces the thick adhesive area of the wafer. This groove compensates for the thick adhesive area, actively counteracting the tendency for adhesive to accumulate at the wafer edges, optimizing the total thickness variation (TTV) on the wafer surface, and controlling wafer warpage. An annular protrusion is located near the edge of the glass carrier, which reduces the thickness of the outermost bonding adhesive, optimizing issues such as voids or delamination at the bonding edges and improving mechanical strength. Furthermore, the annular protrusion allows the adhesive to flow more effectively into the annular groove.
[0030] Furthermore, in one embodiment, periodic first micro-protrusions (not shown in the figure) are provided within the annular groove 102 to disrupt the continuous flow of bonding adhesive, thereby suppressing the formation of thick adhesive regions on the wafer. The height of the first micro-protrusions is generally between 1 and 5 μm.
[0031] Furthermore, the applicant discovered that for large-size interposer wafers, the wide dicing channels result in significant differences in wafer surface structure, leading to insufficient bonding adhesive filling and air bubbles in the dicing channel area after temporary bonding. To address this issue, in one embodiment, reference is made to... Figure 1 A second micro-bump 104 is provided on the bonding surface 100. The second micro-bump 104 is directly opposite the dicing area of the wafer to enhance local pressure, suppress the generation of bubbles in the dicing area of the wafer and balance stress.
[0032] The second micro-protrusion 104 has an arc-shaped cross-section, with a center height between 1 and 10 μm and a radius of curvature between 50 and 200 μm. The center height and width of the second micro-protrusion 104 are both on the micrometer scale, hence the radius of curvature is also on the micrometer scale. The cross-section of the second micro-protrusion 104 can be understood as a large portion of an arc on a micrometer-scale circle. Of course, the structure of the second micro-protrusion is not limited to this; for example, the cross-sectional shape of the second micro-protrusion 104 can also be triangular or other shapes.
[0033] Figure 2 This is a magnified side view of the annular protrusion 101, the annular groove 102, and the second micro-protrusion 104. Figure 2 As shown, a portion of the bonding surface 100 of the glass carrier (right side of the above figure) is flat. This flat surface can be referred to as the flat area of the bonding surface. The center height of the annular protrusion 101, the depth of the annular groove 102, and the center height of the second micro-protrusion 104 are all based on the flat area of the bonding surface 100 of the glass carrier. For example, in Figure 2 In the design, the center height of the annular protrusion 101 is 0.050 mm (i.e., 50 μm), the depth of the annular groove 102 is 0.100 mm (i.e., 100 μm), and the center height of the second micro-protrusion 104 is 0.010 mm (i.e., 10 μm). The edges of the annular protrusion 101 and the annular groove 102 are directly connected.
[0034] Furthermore, in one embodiment, reference is made to... Figure 1 Multiple radially distributed third micro-protrusions 105 are provided on the bonding surface 100 to guide the bonding adhesive. The height of the third micro-protrusions 105 is less than 3 μm, and they can be teardrop-shaped or cylindrical, but are not limited to these shapes.
[0035] It should also be noted that the glass carrier provided in this embodiment of the invention is used to temporarily bond the wafer. The wafer used can be an interposer wafer in a 2.5D package, which has pre-formed through-silicon vias (TSVs); or it can be a 3D stacked wafer, which has pre-formed hybrid bonds (HBs) or through-silicon vias (TSVs). The interposer wafer or the 3D stacked wafer is temporarily bonded to the glass carrier provided in this embodiment of the invention, and then the TSV exposure process is performed.
[0036] The processing method for the glass carrier provided in the embodiments of the present invention may include the following steps: Select a flat glass substrate with appropriate thickness and coefficient of thermal expansion, and determine the reference conditions of the glass substrate as input for laser processing of microstructures; Laser etching technology is used to achieve curved surface contours, ensuring curvature error <±5%; Polish the surface to an average roughness Ra≤10nm to avoid obstructing the flow of the colloid. The actual curvature of different regions was measured using a white light interferometer and compared with the design value for correction.
[0037] On the other hand, one embodiment of the present invention also provides a wafer temporary bonding method, such as... Figure 3 As shown, the method includes the following steps: S301. Spin-coat bonding adhesive onto the bonding surface of the wafer and bake it. S302. Align the baked wafer and the glass carrier. The glass carrier is the same as the glass carrier in the previous embodiments, and the glass carrier has been spin-coated with a release layer. S303. Heat and pressurize in a sealed vacuum chamber to complete the temporary bonding of the wafer and the glass substrate.
[0038] The aforementioned temporary wafer bonding method is performed in a bonding machine. Segmented speed control and colloid heating enhance fluidity, alleviate edge buildup, and promote the removal of excess colloid from the edges. Specifically, segmented speed control involves first increasing the speed to the main rotation to homogenize the colloid, then thinning the thick colloid by edge washing, and finally periodically accelerating and decelerating to remove excess colloid. After segmented curing, low temperature removes the solvent, medium temperature initiates the initial reaction, and high temperature promotes cross-linking. Following alignment, bonding is performed, with high pressure and temperature further enhancing fluidity and resulting in a smooth bond.
[0039] The wafer temporary bonding method provided in this invention can optimize the total thickness variation (TTV) on the wafer surface, control wafer warpage, and reduce the thickness of the outermost bonding adhesive, avoiding bonding voids or delamination caused by excessively thick edge adhesive, thereby improving mechanical strength.
[0040] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.
[0041] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A glass carrier for temporary bonding of wafers, characterized in that, The glass carrier has a bonding surface, which is an uneven surface. On the bonding surface, an annular protrusion is provided at a first distance from the edge of the glass carrier, and an annular groove is provided at a second distance from the edge of the glass carrier, wherein the first distance is smaller than the second distance; The annular groove is directly opposite the thick adhesive area of the wafer; Both the annular protrusion and the annular groove have arc-shaped cross-sections.
2. The glass carrier according to claim 1, characterized in that, The depth of the annular groove is between 0 and 100 μm, and the width is between 1 and 3 mm.
3. The glass carrier according to claim 1, characterized in that, The center height of the annular protrusion is between 0 and 50 μm, and the radius of curvature of the annular protrusion is between 100 and 300 mm.
4. The glass carrier according to claim 1, characterized in that, The annular groove is provided with periodic first micro-protrusions to break the continuous flow of bonding adhesive, thereby inhibiting the formation of thick adhesive areas on the wafer.
5. The glass carrier according to claim 4, characterized in that, The height of the first micro-protrusion is between 1 and 5 μm.
6. The glass carrier according to claim 1, characterized in that, A second micro-protrusion is provided on the bonding surface, which is directly opposite the dicing area of the wafer to enhance local pressure and suppress the generation of bubbles in the dicing area of the wafer.
7. The glass carrier according to claim 6, characterized in that, The cross-sectional shape of the second micro-protrusion is arc-shaped, with a center height between 1 and 10 μm and a radius of curvature between 50 and 200 μm.
8. The glass carrier according to claim 1, characterized in that, The bonding surface is provided with a plurality of radially distributed third micro-protrusions to guide the bonding adhesive.
9. The glass carrier according to claim 8, characterized in that, The height of the third micro-protrusion is less than 3μm, and it is teardrop-shaped or cylindrical.
10. The glass carrier according to claim 1, characterized in that, The coefficient of thermal expansion of the glass substrate is between 3 and 5 ppm / ℃, and the thickness is between 600 and 850 μm.
11. A method for temporary bonding of wafers, characterized in that, The method includes: Spin-coating bonding adhesive onto the bonding surface of the wafer and then baking it; The baked wafer and glass carrier are aligned, wherein the glass carrier is the glass carrier as described in any one of claims 1 to 10, and the glass carrier has been spin-coated with a release layer; The wafer and the glass substrate are temporarily bonded by heating and pressurizing in a sealed vacuum chamber.