Display device

Abstract

A display device includes a driving backplane and a light-emitting element. The driving backplane includes a substrate, a pixel driving circuit disposed on the substrate, and a pad electrically connected to the pixel driving circuit. The pad has a first metal layer, a first intermetallic layer, and a first diffusion barrier layer, wherein the first metal layer, the first intermetallic layer, and the first diffusion barrier layer are stacked in sequence along a direction away from the substrate. The light-emitting element includes an electrode and a conductive bump electrically connected to the electrode. The conductive bump has a second intermetallic layer, and the first diffusion barrier layer is located between the second intermetallic layer and the first intermetallic layer.

Description

Technical Field

[0001] The invention relates to a display device. Background Art

[0002] The LED display panel includes a driving backplane and a plurality of LED elements transferred to the driving backplane. Inheriting the characteristics of LEDs, the LED display panel has the advantages of power saving, high efficiency, high brightness and fast response time. In addition, compared with the organic light-emitting diode display panel, the LED display panel also has the advantages of easy color adjustment, long light-emitting life and no image burn-in. Therefore, the LED display panel is regarded as the next generation of display technology.

[0003] Generally speaking, a coating is required on the pads of the driving backplane of the LED display panel to facilitate the bonding with the conductive bumps of the light-emitting element in the subsequent process. However, in the process of forming the coating on the pads of the driving backplane by electrochemical principle, a large amount of hazardous waste liquid is generated, and the material cost of the coating (e.g., nickel-gold layer) is high. Summary of the invention

[0004] The object of the present invention is to provide a display device with good performance.

[0005] The display device of the present invention includes a driving backplane and a light-emitting element. The driving backplane includes a substrate, a pixel driving circuit disposed on the substrate, and a pad electrically connected to the pixel driving circuit. The pad has a first metal layer, a first intermetallic layer, and a first diffusion barrier layer, and the first metal layer, the first intermetallic layer, and the first diffusion barrier layer are stacked in sequence along a direction away from the substrate. The light-emitting element includes an electrode and a conductive bump electrically connected to the electrode. The conductive bump has a second intermetallic layer, and the first diffusion barrier layer is located between the second intermetallic layer and the first intermetallic layer.

[0006] In one embodiment of the present invention, the first metal layer includes copper, and the first intermetallic layer includes copper and tin.

[0007] In one embodiment of the present invention, the first metal layer includes copper, and the second intermetallic layer includes copper and tin.

[0008] In one embodiment of the present invention, the first intermetallic layer includes (Cu, Ni)6Sn5, (Cu, Ni)3Sn, (Cu, Ni)3Sn4 or a combination of at least two thereof.

[0009] In one embodiment of the present invention, the second intermetallic layer includes (Cu, Ni)6Sn5, (Cu, Ni)3Sn, (Cu, Ni)3Sn4 or a combination of at least two thereof.

[0010] In one embodiment of the present invention, the first diffusion barrier layer includes tungsten and nickel.

[0011] In one embodiment of the present invention, the first diffusion barrier layer further includes copper, tin, or a combination of copper and tin.

[0012] In one embodiment of the present invention, the weight percentage of tungsten in the first diffusion barrier layer is in a range of 15% to 70%.

[0013] In one embodiment of the present invention, the weight percentage of nickel in the first diffusion barrier layer is greater than 5%.

[0014] In one embodiment of the present invention, the pad further comprises an auxiliary metal layer and an auxiliary protective layer, and the auxiliary metal layer, the auxiliary protective layer, the first metal layer, the first intermetallic layer, the first diffusion barrier layer and the second intermetallic layer are stacked in sequence along a direction away from the substrate.

[0015] The beneficial effect of the present invention is that, during the manufacturing process of the display device of one embodiment of the present invention, a first protective layer can be sputtered on the first metal layer of the pad of the driving backplane. Before the driving backplane is bonded to the light-emitting element, the first protective layer can prevent the first metal layer of the pad from being oxidized, so as to ensure that the pad of the driving backplane can be smoothly bonded to the light-emitting element in the subsequent process. During the bonding process between the driving backplane and the light-emitting element, part of the second metal layer of the conductive bump of the light-emitting element can pass through the first protective layer of the pad and diffuse to the first metal layer of the pad, and react with part of the first metal layer of the pad to generate a first intermetallic; thereby, the light-emitting element can be well bonded to the driving backplane. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1A to Figure 1B FIG. 4 is a cross-sectional schematic diagram of a manufacturing process of a display device according to an embodiment of the present invention.

[0017] Figure 2 The figure is a photograph of a partial cross section of a display device according to an embodiment of the present invention taken using an electron microscope.

[0018] Figure 3 The figure is a photograph of a partial cross section of a display device according to an embodiment of the present invention taken using an electron microscope.

[0019] Figure 4 The figure is a photograph of a partial cross section of a display device according to an embodiment of the present invention taken using an electron microscope.

[0020] FIG. 5A to FIG. 5B FIG. 4 is a cross-sectional schematic diagram of a manufacturing process of a display device according to an embodiment of the present invention.

[0021] FIG. 6A to FIG. 6D FIG. 4 is a cross-sectional schematic diagram of a repair process of a display device according to an embodiment of the present invention.

[0022] The reference numerals are as follows:

[0023] 10, 10A, 10B, 10B': display device

[0024] 100, 100A: driver backplane

[0025] 110: Base

[0026] 120: Pixel driving circuit

[0027] 130: First metal layer

[0028] 130a, 130b, 150a, 150b: Part

[0029] 132b: first intermetallic layer

[0030] 140: First protective layer

[0031] 142: first diffusion barrier layer

[0032] 150: auxiliary metal layer

[0033] 152b: fourth intermetallic layer

[0034] 160: auxiliary protective layer

[0035] 162: Second diffusion barrier layer

[0036] 200, 200': Light emitting element

[0037] 210: first type semiconductor layer

[0038] 220: Second type semiconductor layer

[0039] 230: Active layer

[0040] 242, 244: Electrode

[0041] 250: Second metal layer

[0042] 250a: Second intermetallic layer

[0043] 250b: third intermetallic layer

[0044] 252, 254: conductive bumps

[0045] P1, P2: pads

[0046] T:Thickness

[0047] z: direction DETAILED DESCRIPTION

[0048] Reference will now be made in detail to exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals are used in the drawings and the description to refer to the same or like parts.

[0049] It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected to" another element, it may be directly on or connected to another element, or an intermediate element may also exist. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intermediate elements. As used herein, "connection" may refer to physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" may refer to the presence of other elements between two elements.

[0050] As used herein, "about", "approximately", or "substantially" includes the stated value and the average value within an acceptable deviation range of the particular value determined by one of ordinary skill in the art, taking into account the measurement in question and the particular amount of error associated with the measurement (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations of the stated value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, as used herein, "about", "approximately", or "substantially" can select a more acceptable deviation range or standard deviation depending on the optical property, etching property or other property, and can apply to all properties without a single standard deviation.

[0051] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and the present invention, and will not be interpreted as an idealized or overly formal meaning unless explicitly defined as such herein.

[0052] Figure 1A to Figure 1B FIG. 1 is a cross-sectional schematic diagram of a manufacturing process of a display device 10 according to an embodiment of the present invention.

[0053] Please refer to Figure 1A First, a driving backplane 100 is provided. The driving backplane 100 includes a substrate 110. For example, in this embodiment, the substrate 110 may be made of glass, quartz, organic polymer, or other applicable materials.

[0054] The driving backplane 100 further includes a pixel driving circuit 120, which is disposed on the substrate 110. For example, in the present embodiment, the pixel driving circuit 120 may include a data line (not shown), a scan line (not shown), a power line (not shown), a common line (not shown), a first transistor (not shown), a second transistor (not shown) and a capacitor (not shown), wherein a first end of the first transistor is electrically connected to the data line, a control end of the first transistor is electrically connected to the scan line, a second end of the first transistor is electrically connected to a control end of the second transistor, a first end of the second transistor is electrically connected to the power line, and the capacitor is electrically connected to the second end of the first transistor and the first end of the second transistor. However, the present invention is not limited thereto, and in other embodiments, the pixel driving circuit 120 may also be other types of circuits.

[0055] The driving backplane 100 further includes pads P1 and P2 electrically connected to the pixel driving circuit 120. For example, in the present embodiment, the pads P1 and P2 include a first pad P1 and a second pad P2 that are structurally separated from each other, wherein the first pad P1 is electrically connected to the second end (not shown) of the second transistor of the pixel driving circuit 120, and the second pad P2 is electrically connected to the common line (not shown) of the pixel driving circuit 120, but the present invention is not limited thereto.

[0056] Each pad P1, P2 has a first metal layer 130 and a first protective layer 140 covering the first metal layer 130. The first protective layer 140 can protect the first metal layer 130, so that the first metal layer 130 is not easily oxidized. In this embodiment, the thickness T of the first protective layer 140 can fall within the range of 5nm to 50nm, but the present invention is not limited thereto.

[0057] In the present embodiment, the first metal layer 130 may be selectively a copper layer, and the first protective layer 140 may be diffused with copper at a high temperature (e.g., 150° C. to 300° C.). The first protective layer 140 may be an inorganic layer or an organic layer. Further, the first protective layer 140 may be a metal, an alloy, a ceramic, a metal oxide, or a nitride. For example, the first protective layer 140 may be chromium (Cr), a copper alloy, molybdenum (Mo), a molybdenum alloy, silicon oxide (SiOx), nitride oxide (SiNx), tantalum (Ta), a tantalum alloy, aluminum oxide (AlOx), indium tin oxide (ITO), indium zinc oxide (IZO), aluminum zinc oxide (AZO), titanium nitride (TiNx), tungsten (W), tungsten alloy, silicon (Si), sapphire, acrylic polymer (acrylics), or other applicable materials. In the following description, the first protective layer 140 is exemplified by tungsten nickel (WNi), but the present invention is not limited thereto.

[0058] Please refer to Figure 1A, then, a light emitting element 200 is provided. In the present embodiment, the light emitting element 200 is, for example, a micro light emitting diode (μLED). The light emitting element 200 includes electrodes 242, 244 and conductive bumps 252, 254 electrically connected to the electrodes 242, 244. In detail, in the present embodiment, the light emitting element 200 also includes a first-type semiconductor layer 210, a second-type semiconductor layer 220 and an active layer 230, the active layer 230 is disposed between the first-type semiconductor layer 210 and the second-type semiconductor layer 220, the electrodes 242, 244 include a first electrode 242 and a second electrode 244, the first electrode 242 and the second electrode 244 are electrically connected to the first-type semiconductor layer 210 and the second-type semiconductor layer 220, respectively, and the conductive bumps 252, 254 include a first conductive bump 252 and a second conductive bump 254, the first conductive bump 252 and the second conductive bump 254 are electrically connected to the first electrode 242 and the second electrode 244, respectively. Each of the conductive bumps 252 and 254 includes a second metal layer 250. For example, in this embodiment, the second metal layer 250 includes tin (Sn), but the invention is not limited thereto.

[0059] Please refer to Figure 1A and Figure 1B Then, the light emitting element 200 is transferred to the driving backplane 100, and the light emitting element 200 is electrically connected to the driving backplane 100. Specifically, in the present embodiment, a heating process can be performed to eutectic bond the conductive bumps 252 and 254 of the light emitting element 200 with the pads P1 and P2 of the driving backplane 100. During the eutectic bonding process, a portion of the second metal layer 250 of the conductive bumps 252 and 254 will pass through the first protective layer 140 and diffuse toward the first metal layer 130, so that a portion 130b of the first metal layer 130 of the pads P1 and P2 reacts with a portion of the second metal layer 250 diffused therein to form a first intermetallic layer 132b; at the same time, a portion of the first metal layer 130 of the pads P1 and P2 will pass through the first protective layer 140 and diffuse toward the second metal layer 250, so that at least a portion of the second metal layer 250 reacts with a portion of the first metal layer 130 diffused therein to form a second intermetallic layer 250a.

[0060] In the present embodiment, during the eutectic bonding process, the first protective layer 140 has the function of preventing continuous rapid diffusion. Due to the barrier function of the first protective layer 140, a portion 130a of the first metal layer 130 of the pads P1 and P2 close to the substrate 110 will not react with other substances and retain the original characteristics of the first metal layer 130. In addition, during the eutectic bonding process, since part of the second metal layer 250 and part of the first metal layer 130 will each pass through the first protective layer 140 and diffuse toward each other, a trace amount of the first metal in the first metal layer 130 and a trace amount of the second metal in the second metal layer 250 will also diffuse and remain in the first protective layer 140, so that the first protective layer 140 is transformed into a first diffusion barrier layer 142 having trace amounts of the first metal and the second metal. At this point, the display device 10 of the present embodiment is completed.

[0061] Please refer to Figure 1B The display device 10 includes a driving backplane 100 and a light-emitting element 200. The driving backplane 100 includes a substrate 110, a pixel driving circuit 120 disposed on the substrate 110, and pads P1 and P2 electrically connected to the pixel driving circuit 120. The pads P1 and P2 have a first metal layer 130, a first intermetallic layer 132b, and a first diffusion barrier layer 142, wherein the first metal layer 130, the first intermetallic layer 132b, and the first diffusion barrier layer 142 are stacked in sequence along a direction z away from the substrate 110. The light-emitting element 200 includes electrodes 242, 244 and conductive bumps 252, 254, wherein the conductive bumps 252, 254 have a second intermetallic layer 250a, and the first diffusion barrier layer 142 is located between the second intermetallic layer 250a and the first intermetallic layer 132b. In this embodiment, upper and lower sides of the first intermetallic layer 132 b contact the first diffusion barrier layer 142 and the first metal layer 130 respectively, and upper and lower sides of the first diffusion barrier layer 142 contact the second intermetallic layer 250 a and the first intermetallic layer 132 b respectively.

[0062] For example, in this embodiment, the first metal layer 130 includes copper, the first intermetallic layer 132b includes copper and tin, the first diffusion barrier layer 142 includes tungsten and nickel, and the second intermetallic layer 250a includes copper and tin. In this embodiment, the first diffusion barrier layer 142 also includes copper, tin, or a combination of copper and tin.

[0063] In this embodiment, the first intermetallic layer 132b includes (Cu ， Ni)6Sn5、(Cu ， Ni)3Sn、(Cu ， Ni)3Sn4, or a combination of at least two of the above, wherein 0.05≤x≤0.7, 0.05≤y≤0.7, and 0.1≤z≤0.9. More specifically, in this embodiment, the first intermetallic layer 132b includes Cu6Sn5, (Cu1-x Ni x )6Sn5、Cu3Sn、(Cu 1-y Ni y )3Sn、(Cu 1-z Ni z )3Sn4, or a combination of at least two of the above. In this embodiment, the first diffusion barrier layer 142 includes, for example, tungsten nickel (WNi), but the present invention is not limited thereto. In this embodiment, the second intermetallic layer 250a includes (Cu ， Ni)6Sn5、(Cu ， Ni)3Sn、(Cu ， Ni)3Sn4, or a combination of at least two of the above. More specifically, in this embodiment, the second intermetallic layer 250a includes Cu6Sn5, (Cu 1-x Ni x )6Sn5、Cu3Sn、(Cu 1-y Ni y )3Sn、(Cu 1-z Ni z )3Sn4, or a combination of at least two of the above, wherein 0.05≤x≤0.7, 0.05≤y≤0.7, and 0.1≤z≤0.9.

[0064] In this embodiment, the weight percentage of tungsten in the first diffusion barrier layer 142 may be in the range of 15% to 70%; the weight percentage of nickel in the first diffusion barrier layer 142 may be greater than 5%; but the invention is not limited thereto.

[0065] Table 1 shows Figure 1A When the first metal layer 130 of the pads P1 and P2 includes copper and the thickness of the copper is 600 nm, Figure 1A The composition and thickness T of the first protective layer 140 of the pads P1 and P2 are Figure 1B The relationship between the bonding result of the light emitting element 200 and the driving backplane 100 is shown in Table 1. Please refer to Table 1. From the experimental results in Table 1, it can be seen that when the thickness T of the first protective layer 140 (i.e., tungsten nickelide) is 500nm and 300nm, the bonding between the light emitting element 200 and the driving backplane 100 is poor; when the thickness T of the first protective layer 140 (i.e., tungsten nickelide) is 40nm and 20nm, the bonding between the light emitting element 200 and the driving backplane 100 is good. It can be seen that in one embodiment, the thickness T of the first protective layer 140 (i.e., tungsten nickelide) is preferably less than or equal to 40nm.

[0066]

[0067] [Table 1]

[0068] Please refer to Figure 1AAnd the third row from the right side of Table 1, in one embodiment, the composition of the first protective layer 140 of the pads P1 and P2 includes nickel tungsten, the weight percentage of tungsten in the nickel tungsten is 60%, the weight percentage of nickel in the nickel tungsten is 40%, and the thickness T of the nickel tungsten is 20nm. Figure 2 FIG. 1 is a photograph of a partial cross section of a display device according to an embodiment of the present invention taken using an electron microscope. Figure 2 The photograph is a partial cross-sectional view of the display device 10 formed using the pads P1 and P2 including the first protection layer 140 described in this paragraph.

[0069] Please refer to Figure 1A , Figure 1B and Figure 2 In one embodiment, the first protective layer 140 of the pads P1 and P2 includes nickel tungsten, the weight percentage of tungsten in the nickel tungsten is 60%, the weight percentage of nickel in the nickel tungsten is 40%, and the thickness T of the first protective layer 140 (ie, nickel tungsten) is 20nm; Figure 2 It can be found that the pads P1 and P2 including the first protective layer 140 described in this paragraph, after eutectic bonding, the amount of the first intermetallic layer 132b (dark shaded area) and the second intermetallic layer 250a (dark shaded area) generated is relatively small. In other words, the first protective layer 140 (i.e., nickel tungsten) with a weight percentage of 60% tungsten and a weight percentage of 40% nickel can make the light-emitting element 200 bonded to the driving backplane 100, but the bonding between the two is not ideal.

[0070] Please refer to Figure 1A And the second row from the right side of Table 1, in one embodiment, the composition of the first protective layer 140 of the pads P1 and P2 includes nickel tungsten, the weight percentage of tungsten in the nickel tungsten is 50%, the weight percentage of nickel in the nickel tungsten is 50%, and the thickness T of the first protective layer 140 (i.e., nickel tungsten) is 20nm. Figure 3 This is a photograph of a partial cross section of a display device according to an embodiment of the present invention taken using an electron microscope. Figure 1A , Figure 1B and Figure 3 , in detail, Figure 3 The photograph is a partial cross-sectional view of the display device 10 formed using the pads P1 and P2 including the first protection layer 140 described in this paragraph.

[0071] Please refer to Figure 1A , Figure 1B and Figure 3 In one embodiment, the first protective layer 140 of the pads P1 and P2 includes nickel tungsten, the weight percentage of tungsten in the nickel tungsten is 50%, the weight percentage of nickel in the nickel tungsten is 50%, and the thickness T of the first protective layer 140 (ie, nickel tungsten) is 20nm; Figure 3It can be found that the pads P1 and P2 including the first protective layer 140 described in this paragraph can generate a continuous and complete first intermetallic layer 132b and a second intermetallic layer 250a (dark shaded area) after eutectic bonding. In other words, the first protective layer 140 (i.e., nickel tungsten) with a weight percentage of 50% tungsten and a weight percentage of 50% nickel can make the light-emitting element 200 and the driving backplane 100 bonded, and the bonding condition of the two is ideal.

[0072] Please refer to Figure 1A And the first row from the right side of Table 1, in one embodiment, the composition of the first protective layer 140 of the pads P1 and P2 includes nickel tungsten, the weight percentage of tungsten in the nickel tungsten is 40%, the weight percentage of nickel in the nickel tungsten is 60%, and the thickness T of the first protective layer 140 (i.e., nickel tungsten) is 20nm. Figure 4 This is a photograph of a partial cross section of a display device according to an embodiment of the present invention taken using an electron microscope. Figure 1A , Figure 1B and Figure 4 , in detail, Figure 4 The photograph is a partial cross-sectional view of the display device 10 formed using the pads P1 and P2 including the first protection layer 140 described in this paragraph.

[0073] Please refer to Figure 1A , Figure 1B and Figure 4 In one embodiment, the first protective layer 140 of the pads P1 and P2 includes tungsten nickel, the weight percentage of tungsten in the tungsten nickel is 40%, the weight percentage of nickel in the tungsten nickel is 60%, and the thickness T of the first protective layer 140 (i.e., tungsten nickel) is 20 nm; Figure 4 It can be found that the pads P1 and P2 including the first protective layer 140 described in this paragraph can generate sufficient first intermetallic layer 132b and second intermetallic layer 250a after eutectic bonding. In other words, the first protective layer 140 (i.e., nickel tungsten) with a weight percentage of 40% tungsten and a weight percentage of 60% nickel can make the light emitting element 200 and the driving backplane 100 bonded, and the bonding condition of the two is still ideal.

[0074] comprehensive Figure 2 , Figure 3 and Figure 4 The experimental results show that Figure 1A The weight percentage of tungsten in the first protective layer 140 (ie, tungsten nickel) of the pads P1 and P2 is preferably 5% to 60%, and the weight percentage of nickel in the first protective layer 140 of the pads P1 and P2 is preferably greater than 40%, but the present invention is not limited thereto.

[0075] Table 2 shows Figure 1AWhen the first metal layer 130 of the pads P1 and P2 includes copper and the thickness of the copper is 600 nm, and the first protective layer 140 of the pads P1 and P2 includes tungsten nickel and the thickness of the tungsten nickel is 20 nm, the process parameters of various heating processes are Figure 1B The relationship between the bonding result of the light emitting element 200 and the driving backplane 100.

[0076] Please refer to Table 2. When the heating temperature of the heating process is 230°C and the heating time is 30 seconds, the bonding result of the light emitting element 200 and the driving backplane 100 is good. Under the process parameters of the degraded heating process (i.e., the heating time of the heating process is extended to 60 seconds), the bonding result of the light emitting element 200 and the driving backplane 100 is also good. It can be seen that even under the process conditions of the degraded heating process, the light emitting element 200 can still be well bonded to the driving backplane 100.

[0077]

[0078] [Table 2]

[0079] Table 3 shows Figure 1A The oxygen content of the first metal layer 130 of the various pads P1 and P2 after being heated at 160° C. / 4 hr on a hot plate.

[0080]

[0081] [Table 3]

[0082] From the experimental results in Table 3, it can be seen that after the pads P1 and P2 of the driving backplane 100 are heated for a long time at high temperature, the first metal layer 130 of the pads P1 and P2 is not easily oxidized. Therefore, it can be seen that even if the multiple pads P1 and P2 of the driving backplane 100 and the multiple light-emitting elements 200 are bonded to each other after multiple heating processes, the pads P1 and P2 that remain on the driving backplane 100 and have not been bonded are also heated in the above-mentioned multiple heating processes, but the first protective layer 140 of the pads P1 and P2 that have not been bonded still has the function of protecting its first metal layer 130 from oxidation.

[0083] It must be noted that the following embodiments use the component numbers and some contents of the previous embodiments, wherein the same number is used to represent the same or similar components, and the description of the same technical contents is omitted. The description of the omitted parts can refer to the previous embodiments, and the following embodiments will not be repeated.

[0084] FIG. 5A to FIG. 5B FIG. 1 is a cross-sectional diagram of a manufacturing process of a display device 10A according to an embodiment of the present invention.

[0085] FIG. 5A to FIG. 5B Display device 10A and manufacturing process thereof Figure 1A to Figure 1B The display device 10 and the manufacturing process thereof are similar, and the difference between the two is that the pads P1 and P2 are different.

[0086] Please refer to Figure 5A In this embodiment, the pads P1 and P2 further include an auxiliary metal layer 150 and an auxiliary protective layer 160. Before the light emitting element 200 is bonded, the auxiliary metal layer 150, the auxiliary protective layer 160, the first metal layer 130 and the first protective layer 140 are stacked in sequence along a direction z away from the substrate 110. In this embodiment, the applicable materials of the auxiliary metal layer 150 and the auxiliary protective layer 160 can refer to the applicable materials of the aforementioned first metal layer 130 and the first protective layer 140, respectively, and will not be repeated here.

[0087] Please refer to Figure 5A and Figure 5B In the present embodiment, during the bonding process of the light-emitting element 200, a portion of the second metal layer 250 of the conductive bumps 252 and 254 will pass through the first protective layer 140 and diffuse toward the first metal layer 130, so that a portion 130b of the first metal layer 130 of the pads P1 and P2 reacts with a portion of the second metal layer 250 diffused therein to generate a first intermetallic layer 132b; at the same time, a portion of the first metal layer 130 of the pads P1 and P2 will pass through the first protective layer 140 and diffuse toward the second metal layer 250, so that at least a portion of the second metal layer 250 reacts with a portion of the first metal layer 130 diffused therein to generate a second intermetallic layer 250a. In this embodiment, since the auxiliary metal layer 150 and the auxiliary protective layer 160 are disposed below the first metal layer 130 and the first protective layer 140, the second metal layer 250 may not diffuse into the auxiliary metal layer 150 and the auxiliary protective layer 160 during the eutectic bonding process, and the auxiliary metal layer 150 and the auxiliary protective layer 160 may still retain their original properties. Figure 5B In the present embodiment, after the light emitting element 200 is bonded, the auxiliary metal layer 150 , the auxiliary protection layer 160 , the first metal layer 130 , the first intermetallic layer 132 b , the first diffusion barrier layer 142 and the second intermetallic layer 250 a are stacked in sequence along a direction z away from the substrate 110 .

[0088] Please refer to Figure 5B In this embodiment, the pads P1 and P2 can not only be well bonded with the light emitting element 200, but also, if the light emitting element 200 bonded with the pads P1 and P2 is found to be abnormal, after the abnormal light emitting element 200 is removed from the pads P1 and P2, the part of the pads P1 and P2 remaining on the substrate 110 can also be bonded with the repair light emitting element 200' (shown in FIG. Figure 6C and Fig.6D ) are well joined, the following fit FIG. 6A to FIG. 6D Let me illustrate this with an example.

[0089] FIG. 6A to FIG. 6D FIG. 1 is a cross-sectional schematic diagram of a repair process of a display device 10B according to an embodiment of the present invention.

[0090] Please refer to Fig. 6A , Fig. 6A The display device 10B and Figure 5B The display device 10A is similar to the display device 10A, and the difference between the two is: Figure 5B The light emitting element 200 is normal, but Fig. 6A The light emitting element 200 is abnormal and needs to be removed.

[0091] Please refer to Fig. 6A and Figure 6B When the abnormal light-emitting element 200 is removed from the substrate 110, in addition to the first semiconductor layer 210, the second semiconductor layer 220, the active layer 230 and the electrodes 242 and 244 of the light-emitting element 200 being removed, the second intermetallic layer 250a, the first diffusion barrier layer 142 and the first intermetallic layer 132b are also removed, leaving the first metal layer 130, the auxiliary protection layer 160 and the auxiliary metal layer 150 of the pads P1 and P2.

[0092] Please refer to Figure 6C and Fig.6D Next, the repaired light emitting element 200 ′ is transferred to the driving backplane 100A, and the electrodes 242 , 244 of the light emitting element 200 ′ are electrically connected to the remaining pads P1 , P2 .

[0093] Specifically, in this embodiment, a heating process may be performed to eutectic bond the conductive bumps 252 and 254 of the repaired light emitting element 200' with the remaining pads P1 and P2. During the eutectic bonding process, a portion of the second metal layer 250 of the conductive bumps 252 and 254 and the first metal layer 130 of the remaining pads P1 and P2 will react to form a third intermetallic layer 250b, and a portion of the second metal layer 250 of the conductive bumps 252 and 254 will pass through the auxiliary protection layer 160 and diffuse toward the auxiliary metal layer 150, so that a portion 150b of the auxiliary metal layer 150 reacts with a portion of the second metal layer 250 diffused therein to form a fourth intermetallic layer 152b.

[0094] In this embodiment, during the eutectic bonding process, the auxiliary protective layer 160 has the function of preventing continuous rapid diffusion. Due to the barrier effect of the auxiliary protective layer 160, a portion 150a of the auxiliary metal layer 150 of the pads P1 and P2 close to the substrate 110 will not react with other substances and retain the original characteristics of the auxiliary metal layer 150. In addition, during the eutectic bonding process, since part of the second metal layer 250 will pass through the auxiliary protective layer 160 and diffuse toward the auxiliary metal layer 150, a trace amount of the second metal in the second metal layer 250 will also diffuse and remain in the auxiliary protective layer 160, so that the protective layer 160 is transformed into a second diffusion barrier layer 162 with a trace amount of the second metal. At this point, the repaired display device 10B' is completed. In the repaired display device 10B', the auxiliary metal layer 150, the fourth intermetallic layer 152b, the second diffusion barrier layer 162 and the third intermetallic layer 250b are stacked in sequence along the direction z away from the substrate 110.

[0095] In summary, in the manufacturing process of the display device of one embodiment of the present invention, a first protective layer can be sputtered on the first metal layer of the pad of the driving backplane. Before the driving backplane is bonded to the light-emitting element, the first protective layer can prevent the first metal layer of the pad from being oxidized to ensure that the pad of the driving backplane can be smoothly bonded to the light-emitting element in the subsequent process. In the process of bonding the driving backplane to the light-emitting element, part of the second metal layer of the conductive bump of the light-emitting element can pass through the first protective layer of the pad and diffuse to the first metal layer of the pad, and react with part of the first metal layer of the pad to generate a first intermetallic; thereby, the light-emitting element can be well bonded to the driving backplane.

[0096] It is worth noting that compared with the metal or its compound plated on the first metal layer of the pad through the electrochemical principle, forming the first protective layer on the first metal layer of the pad through the sputtering process is less likely to generate hazardous waste liquid and has low material cost.

Claims

1. A display device, comprising: A drive backplane, comprising: a base; a pixel driving circuit, disposed on the substrate; and a pad electrically connected to the pixel driving circuit, wherein the pad has a first metal layer, a first intermetallic layer and a first diffusion barrier layer, and the first metal layer, the first intermetallic layer and the first diffusion barrier layer are stacked in sequence along a direction away from the substrate; and A light emitting element, comprising: an electrode; and a conductive bump electrically connected to the electrode, wherein the conductive bump has a second intermetallic layer, and the first diffusion barrier layer is located between the second intermetallic layer and the first intermetallic layer; The first diffusion barrier layer includes tungsten and nickel, and the weight percentage of tungsten in the first diffusion barrier layer falls within a range of 15% to 70%. 2 . The display device as claimed in claim 1 , wherein the first metal layer comprises copper, and the first intermetallic layer comprises copper and tin. 3 . The display device as claimed in claim 1 , wherein the first metal layer comprises copper, and the second intermetallic layer comprises copper and tin.

4. The display device as claimed in claim 1, wherein the first intermetallic layer comprises (Cu, Ni)6Sn5, (Cu, Ni)3Sn, (Cu, Ni)3Sn4 or a combination of at least two thereof.

5. The display device as claimed in claim 1, wherein the second intermetallic layer comprises (Cu, Ni)6Sn5, (Cu, Ni)3Sn, (Cu, Ni)3Sn4 or a combination of at least two thereof. The display device as claimed in claim 1 , wherein the first diffusion barrier layer further comprises copper, tin, or a combination of copper and tin. 7 . The display device as claimed in claim 1 , wherein a weight percentage of nickel in the first diffusion barrier layer is greater than 5%.

8. The display device as described in claim 1, wherein the pad further comprises an auxiliary metal layer and an auxiliary protective layer, and the auxiliary metal layer, the auxiliary protective layer, the first metal layer, the first intermetallic layer, the first diffusion barrier layer and the second intermetallic layer are stacked in sequence along the direction away from the substrate.

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