Semiconductor structure

Abstract

An embodiment of the present invention relates to a semiconductor structure. The semiconductor structure includes a metallization structure, a plurality of conductive pads and a dielectric layer. The plurality of conductive pads are above the metallization structure. The dielectric layer is on the metallization structure and covers the conductive pads. The dielectric layer includes a first dielectric film, a second dielectric film and a third dielectric film. The first dielectric film is on the conductive pad. The second dielectric film is on the first dielectric film. The third dielectric film is on the second dielectric film. The refractive index of the first dielectric film is less than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is less than the refractive index of the third dielectric film.

Description

Technical Field

[0001] An embodiment of the present invention relates to a semiconductor structure. Background Art

[0002] Displays made of organic light-emitting diodes (OLEDs) have the advantages of being thin, flexible, power-saving, portable, high brightness, no viewing angle restrictions, and fast response speed, and are an important trend in display development. Generally speaking, the display technology of organic light-emitting diodes consists of organic material layers and glass pads or CMOS pads. When charges pass through, these organic material layers will emit light, and the color of the light emitted may depend on the material of the organic light-emitting layer. Summary of the invention

[0003] An embodiment of the present invention relates to a reflective structure, comprising: a metal substrate having a first surface; and a dielectric layer on the first surface, the dielectric layer comprising: a first dielectric film on the first surface; a second dielectric film on the first dielectric film; and a third dielectric film on the second dielectric film; wherein the refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film.

[0004] An embodiment of the present invention relates to a reflective structure, which includes: a first metal substrate and a second metal substrate, which are above an interconnect structure; a first dielectric film, which has a first thickness on the first metal substrate and a second thickness on the second metal substrate, the first thickness is different from the second thickness; a second dielectric film, which is on the first dielectric film, the second dielectric film has a third thickness above the first metal substrate and a fourth thickness above the second metal substrate, the third thickness is different from the fourth thickness; and a third dielectric film, which is on the second dielectric film, the third dielectric film has a fifth thickness above the first metal substrate and a sixth thickness above the second metal substrate, the fifth thickness is different from the sixth thickness; wherein the refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film.

[0005] An embodiment of the present invention relates to a semiconductor structure, which includes: a metallization structure; a plurality of conductive pads above the metallization structure; and a dielectric layer on the metallization structure and covering the conductive pads, the dielectric layer including: a first dielectric film on the conductive pads; a second dielectric film on the first dielectric film; and a third dielectric film on the second dielectric film; wherein the refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] When read in conjunction with the accompanying drawings, aspects of the present disclosure are better understood from the following embodiments. It should be noted that, in accordance with standard practice in the industry, various structures are not drawn to scale. In fact, for clarity of discussion, the dimensions of various structures may be arbitrarily increased or reduced.

[0007] Figure 1 A cross-sectional view illustrating a reflective structure according to some embodiments of the present disclosure.

[0008] Figure 2 Graphs illustrating reflectivity and refractive index of a second dielectric film according to some embodiments of the present disclosure.

[0009] Figure 3 A cross-sectional view illustrating a reflective structure according to some embodiments of the present disclosure.

[0010] Figure 4 A line graph illustrating total reflectivity and dielectric film count according to some embodiments of the present disclosure.

[0011] Figure 5 A cross-sectional view illustrating a reflective structure according to some embodiments of the present disclosure.

[0012] Fig. 6A , Figure 6B , Figure 6C , Fig.6D , Fig. 6E , Fig. 6Ea , Fig. 6F , Figure 6Fa , Figure 6G , Figure 6H and Fig.6I Cross-sectional views illustrating various operations in fabricating a semiconductor structure in accordance with some embodiments of the present disclosure.

[0013] Fig. 7A A scatter plot illustrating total reflectivity of a reflective structure according to some embodiments of the present disclosure.

[0014] Figure 7B A scatter plot illustrating total reflectivity of a reflective structure according to some embodiments of the present disclosure.

[0015] Figure 7C A scatter plot illustrating total reflectivity of a reflective structure according to some embodiments of the present disclosure. DETAILED DESCRIPTION

[0016] The following disclosure provides many different embodiments or examples of different components for implementing the subject matter provided. Specific examples of elements and arrangements are described below to simplify this disclosure. Of course, this type is only an example and is not intended to be restrictive. For example, in the following description, a first component is formed above or on a second component and may include an embodiment in which the first component and the second component are directly contacted through formation, and may also include an embodiment in which an additional component may be formed between the first component and the second component so that the first component and the second component may not directly contact. In addition, this disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or configurations discussed.

[0017] Additionally, for ease of description, spatially relative terms, such as "below," "beneath," "below," "above," "above," "on," and the like, may be used herein to describe one element or component's relationship to another element or component illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should be interpreted similarly.

[0018] As used herein, terms such as "first," "second," and "third" describe various elements, components, regions, layers, and / or sections, but such elements, components, regions, layers, and / or sections should not be limited by such terms. Such terms can only be used to distinguish one element, component, region, layer, or section from another. Terms such as "first," "second," and "third" do not imply a sequence or order when used herein unless clearly indicated by the context.

[0019] Reflectivity is the ratio of the reflected optical power to the incident optical power at the flat surface of an object. It can be affected by several physical properties of the reflective object, such as the surface material type, surface roughness, thickness, uniformity, flatness, geometric structure, etc. of the object. For example, the higher the uniformity of the surface material, the higher the reflectivity that can be presented.

[0020] like Figure 1 As shown in FIG. 1 , in some embodiments, the reflective structure 1 of the present disclosure includes a metal substrate 10 and a dielectric layer 20. The metal substrate 10 has a first surface 101. The dielectric layer 20 includes a first dielectric film 201, a second dielectric film 202, and a third dielectric film 203.

[0021] The metal substrate 10 may be a conductive pad and may be made of any suitable conductive material, including but not limited to metals (e.g., copper, tantalum, titanium, molybdenum, tungsten, platinum, aluminum, hafnium, ruthenium), alloys, metal silicides (e.g., titanium silicide, cobalt silicide, nickel silicide, tantalum silicide), or metal nitrides (e.g., titanium nitride, tantalum nitride). In some embodiments, the metal substrate is made of aluminum copper. In some embodiments, the metal substrate 10 is formed by chemical vapor deposition (CVD), low pressure chemical vapor deposition, physical vapor deposition (PVD), atomic layer deposition, or spin coating.

[0022] The dielectric layer 20 is placed on the first surface 101 of the metal substrate 10, and thus, the first dielectric film 201, the second dielectric film 202, and the third dielectric film 203 are stacked above the metal substrate 10. The dielectric layer 20 on the metal substrate 10 is configured to reflect light with the metal substrate 10. More precisely, an incident light irradiated on the metal substrate 10 may first sequentially travel through the third dielectric film 203, the second dielectric film 202, and the first dielectric film 201 before being reflected by the first surface 101 of the metal substrate 10, and the reflected light may then return in the opposite direction.

[0023] Since the dielectric layer 20 is not composed of a single film, incident light and reflected light traveling therein may be affected according to Snell's law. That is, when light travels from one medium to another medium (e.g., from the third dielectric film 203 to the second dielectric film 202), the light may be refracted when the refractive index thereof is different. According to Snell's law, when n1 and n2 represent the refractive indexes of the two media, θ1 and θ2 are the incident angle and the refraction angle formed by the light and the vertical line at the boundary. Snell's law confirms that n1 / n2=sinθ1 / sinθ2.

[0024] In some embodiments, the refractive index of the first dielectric film 201 is smaller than the refractive index of the second dielectric film 202, and the refractive index of the second dielectric film 202 is smaller than the refractive index of the third dielectric film 203. In other words, the refractive index of the dielectric film close to the metal substrate 10 is smaller than the refractive index of the dielectric film far from the metal substrate 10. In some embodiments, the refractive index of the dielectric films changes in ascending order from the bottom of the dielectric layer 20 to the top of the dielectric layer 20.

[0025] In the present disclosure, the refractive index rising from the bottom of the dielectric layer to the top of the dielectric layer can increase the total reflectivity of the light of the reflective structure. In some embodiments, the refractive index of the dielectric film of the dielectric layer 20 is in the range of about 1.47 to about 1.8. In some embodiments, the refractive index of the first dielectric film 201 and the third dielectric film 203 are 1.47 and 1.8, respectively, and the refractive index of the second dielectric film 202 is at a point between 1.47 and 1.8, which is different from the first dielectric film 201 and the third dielectric film 203.

[0026] refer to Figure 2 , Figure 2 The relationship between the total reflectivity (Y-axis) of the dielectric layer 20 and the change of the refractive index (X-axis) of the second dielectric film 202 of the dielectric layer 20 is illustrated. When the refractive index of the second dielectric film 202 increases, the total reflectivity of the light shows an increasing trend. In the case of comparing the refractive index of red light (having a wavelength of about 633 nm, marked as square points) in Examples R1 and R2, when the refractive indexes of the first dielectric film 201 and the second dielectric film 202 are the same, as demonstrated in Example R1, the total reflectivity of about 88.6% is lower than the total reflectivity of about 91.7% of R2, where the refractive index of the first dielectric film 201 is lower than the refractive index of the second dielectric film 202. Alternatively, by changing the refractive index of the second dielectric film 202 from the same to greater than the refractive index of the first dielectric film 201, the reflectivity of the red light in the dielectric layer 20 can be increased from 88.6% to 91.7%, where the refractive index of the third dielectric film 203 is unchanged.

[0027] In addition, if Figure 2 , it is shown that the total reflectivity of not only red light but also green light (e.g., having a wavelength of about 500 nm, marked as triangular points) and the total reflectivity of blue light (e.g., having a wavelength of about 450 nm, marked as diamond points) increases with the increase of the refractive index of the second dielectric film 202. In other words, in the wavelength range of visible light, if the refractive index of the second dielectric film 202 or an intermediate layer of the dielectric film 202 is between the refractive index ranges of the first dielectric film 201 and the third dielectric film 203, the total reflectivity can be increased.

[0028] Moreover, according to Figure 2, the total reflectivity of light shows a positive correlation with the refractive index of the second dielectric film 202. For example, in the case where the refractive indexes of the first dielectric film 201 and the third dielectric film 203 are 1.47 and 1.8, respectively, when the refractive index of the second dielectric film 202 increases from 1.47 to 1.75 (relative to increasing from 1.47 to 1.5), the increase in the total reflectivity of light is more significant. In some embodiments, if the refractive index of the second dielectric film 202 is higher than the average of the refractive indexes of the first dielectric film 201 and the third dielectric film 203, the total reflectivity of light can be further increased. That is, when the refractive index of the first dielectric film 201 is about 1.47 and the refractive index of the third dielectric film 203 is about 1.8, if the refractive index of the second dielectric film 202 is greater than 1.63, the total reflectivity of light can be further increased.

[0029] By increasing the total reflectivity of light by arranging the order of dielectric films, the requirement on the uniformity of dielectric layer 20 can be relaxed. More precisely, to achieve high reflectivity, forming a dielectric layer on a reflective metal requires a strict planarization process to meet a surface roughness uniformity of <1% (3 sigma). However, this requirement on uniformity can be relaxed because the ascending order of the refractive index of the dielectric films can provide an increase in total reflectivity of, for example, more than 3%, such as Figure 2 As a result, manufacturing reflectors in semiconductor structures will be more flexible.

[0030] refer to Figure 3 In some embodiments, the dielectric layer 20 may include more than three dielectric films. In some embodiments, the second dielectric film 202 may include multiple sub-layers, such as Figure 3 202A, 202B, and 202C shown in FIG. In some embodiments, the sublayers 202A, 202B, and 202C are placed between the first dielectric film 201 and the third dielectric film 203. In such embodiments, the refractive indexes of the sublayers 202A, 202B, and 202C are arranged in order such that the sublayer closer to the third dielectric film 203 has a higher refractive index, i.e., the refractive index of the bottom sublayer (e.g., sublayer 202A) of the second dielectric film 202 is less than the refractive index of the top sublayer (e.g., sublayer 202C) of the second dielectric film 202.

[0031] The number of sub-layers of the second dielectric film 202 is not limited to Figure 3 The sublayers shown in . Figure 4 , Figure 4 The relationship between the total reflectivity and the dielectric film count is shown. When the second dielectric film 202 includes four sub-layers, as previously described in Figure 3, the dielectric layer 20 has a film count of six dielectric films in addition to the first dielectric film 201 and the third dielectric film 203. The total reflectivity of light is still higher than that of a reflector having only one or two dielectric films. In other words, in the case where the dielectric layer 20 has a dielectric film count of 3, even if the film count increases, the total reflectivity substantially saturates its performance. Consider Figure 2 and Figure 4 In the case where the raised refractive index from the first dielectric film 201 to the third dielectric film 203 or the intermediate film thereof further comprises a multi-sublayer structure having a raised refractive index, the total reflectivity of light can be increased in this dielectric film arrangement. In some embodiments, the refractive index of the plurality of sublayers is in the range from about 1.47 to about 1.8.

[0032] In some embodiments, the material of the first dielectric film 201 is the same as the material of the second dielectric film 202. In some embodiments, the material of the first dielectric film 201 is silicon oxide. In some embodiments, although the materials of the first dielectric film 201 and the second dielectric film 202 are the same, the refractive indexes of the first dielectric film 201 and the second dielectric film 202 are different by selecting different precursors or adjusting the ratio of the precursors during the dielectric film formation operation.

[0033] In some embodiments, the material of the first dielectric film 201 is different from the material of the third dielectric film 203. In some embodiments, the material of the third dielectric film 203 is aluminum oxide.

[0034] In some embodiments, each of the materials of the first dielectric film 201 , the second dielectric film 202 , and the third dielectric film 203 has an extinction coefficient (k) substantially equal to zero, so that light traveling therethrough may not be substantially attenuated.

[0035] refer to Figure 5 In some embodiments, the conductive oxide layer 40 is placed above the dielectric layer 20, and the conductive pad 30 is placed below the dielectric layer 20. The material and formation method of the conductive pad 30 may refer to those previously described in Figure 1 In some embodiments, the conductive pad 30 is laterally surrounded by the insulating layer 31. In some embodiments, the top surface 310 of the insulating layer 31 is coplanar with the top surface 300 of the conductive pad 30.

[0036] Furthermore, in some embodiments, the dielectric layer 20 includes a protruding portion 21 and a minimal edge portion 22 at one side of the dielectric layer 20. Figure 5 As shown in FIG. 2 , the thickness of the dielectric layer 20 varies in different portions.

[0037] The thickness of the dielectric layer 20 (specifically, the thickness T1 of the protruding portion 21) is associated with the color of the reflected light reflected by the present disclosure. More precisely, the dielectric layer 20 can act as an omni-directional reflector (ODR) to enhance the top surface 300 of the conductive pad 30 to be closer to the light from the light emitting device (e.g., micro OLED, shown later). Fig.6I ) of light. The light emitting device determines the color of the emitted light, and the thickness of the dielectric layer 20 has different effects on the reflectivity of light of different wavelengths, which affects the degree of reflection of light of different colors. In some embodiments, light with a wavelength of about 630nm to about 750nm can be relatively more reflected by the reflective structure having a thickness of the dielectric layer 20 of about 1500 angstroms, thereby improving the reflection efficiency of red light irradiated to the conductive pad 30. In some embodiments, light with a wavelength of about 490nm to about 570nm can be relatively more reflected by the reflective structure having a thickness of the dielectric layer 20 of about 700 angstroms, thereby improving the reflection efficiency of green light irradiated to the conductive pad 30. In some embodiments, light with a wavelength of about 450nm to about 490nm can be relatively more reflected by the reflective structure having a thickness of the dielectric layer 20 of about 50 angstroms, thereby improving the reflection efficiency of blue light irradiated to the conductive pad 30.

[0038] In addition, the thickness T2 of the edge portion 22 is less than the thickness T1 of the protruding portion 21, and in some embodiments, the edge portion 22 is a region not used to reflect visible light. Therefore, in some embodiments, the thickness T2 of the edge portion 22 is less than about 50 angstroms and the edge portion 22 substantially does not reflect visible light.

[0039] Still refer to Figure 5 In some embodiments, the conductive pad 30 is completely covered by the raised portion 21. In some embodiments, not only the conductive pad 30 but also a portion of the insulating layer 31 is covered by the raised portion 21. For example, according to Figure 5 In the cross-sectional view in FIG. 1 , the raised portion 21 may be wider than the conductive pad 30, with a width W at each side of the raised portion 21. Therefore, some oblique incident light may also travel through the raised portion 21 and be reflected. In some embodiments, the area of ​​the raised portion 21 is larger than the area of ​​the conductive pad 30 thereunder. In some embodiments, Figure 5 A portion of a pixel in a light emitting device adjacent to its light receiving side is shown.

[0040] refer to FIG. 6A to FIG. 6H When manufacturing a semiconductor structure having a reflective structure, in some embodiments, a metallization structure 50 may be provided first. Fig. 6A, a metallization structure 50 includes a plurality of individual devices, such as transistors, capacitors, and resistors patterned in a substrate 501 (e.g., a silicon wafer) by a formation operation of the front end of the line (FEOL). A series of stacked layers 502 are placed over the substrate 501 by a formation operation of the back end of the line (BEOL). The stacked layers are fabricated to provide individual devices, such as the transistors, capacitors, and resistors described above, to interconnect with metal wiring on the substrate. Thus, adjacent layers 502 in the metallization structure 50 are connected together by using electrical contacts and vias.

[0041] like Figure 6B , in some embodiments, a plurality of conductive pads 30 are placed above the metallization structure 50. In some embodiments, the plurality of conductive pads 30 are laterally surrounded by an insulating layer 31, and a top surface 310 of the insulating layer 31 is coplanar with a plurality of top surfaces 300 of the conductive pads 30. In some embodiments, the conductive pads 30 may be made of any suitable conductive material, including but not limited to metals, alloys, metal silicides, or metal nitrides. In some embodiments, the conductive pads 30 are made of aluminum copper (AlCu). In some embodiments, the conductive pads 30 are formed by chemical vapor deposition (CVD), low pressure chemical vapor deposition, physical vapor deposition (PVD), atomic layer deposition (ALD), or spin coating.

[0042] Before forming a dielectric layer over the conductive pad 30, in some embodiments, the conductive pad 30 made of aluminum copper may be annealed at about 400 degrees Celsius for about 1 minute. The annealing operation will induce the growth of protrusions or extrusions that form the conductive pad 30 prior to the deposition operation of the dielectric layer. The protrusions or extrusions may be removed by a subsequent chemical mechanical planarization (CMP) operation.

[0043] like FIG. 6C to FIG. 6E , after the CMP operation is performed on the conductive pad 30, a dielectric layer 20 is placed on the conductive pad 30. In some embodiments, the operating temperature of forming the dielectric layer 20 is lower than the annealing operation of the conductive pad 30. In some embodiments, the dielectric layer 20 is formed by plasma enhanced physical vapor deposition (PECVD) at about 250 degrees Celsius. The lower temperature for forming the dielectric layer 20 can maintain a lower surface roughness of the conductive pad 30, that is, if the temperature for forming the dielectric layer 20 is not as high as the temperature in the previous annealing operation, the growth of protrusions or extrusions can be avoided.

[0044] In some embodiments, the surface roughness of the conductive pad 30 made of aluminum copper can be reduced from less than about 350 angstroms to less than about 250 angstroms by annealing the conductive pad 30 at about 400 degrees Celsius for about 1 minute. In some embodiments, the surface roughness of the conductive pad 30 made of aluminum copper can be further reduced from less than about 250 angstroms to less than about 100 angstroms by reducing the PECVD temperature for forming the dielectric layer 20 from about 400 degrees Celsius to about 250 degrees Celsius.

[0045] In some embodiments, the dielectric layer 20 is formed by multiple deposition operations depending on the dielectric film count and the color distribution requirements in the pixel unit. FIG. 6C to FIG. 6E In order to form a reflective structure with different thicknesses for reflecting light of different colors, in some embodiments, a dielectric film is formed over the first conductive pad 30A, the second conductive pad 30B, and the third conductive pad 30C, which can be divided into three different regions 61, 62, and 63 by three mask operations. In some embodiments, the three different regions 61, 62, and 63 may be three pixels configured to reflect different wavelengths, and the three different regions 61, 62, and 63 may be adjacent to or not adjacent to each other in the pixel array.

[0046] In some embodiments, Figure 6C , the region 61 above the conductive pad 30A is for reflecting red light and the total thickness of the dielectric layer 20 therein is about 1500 angstroms. The thicknesses of the first dielectric film 201, the second dielectric film 202, and the third dielectric film 203 may be, for example, about 725 angstroms, 725 angstroms, and 50 angstroms, respectively. Different dielectric films with raised refractive indices may be formed by selecting different precursors or adjusting the ratio of precursors during the first mask operation.

[0047] In some embodiments, Fig.6D , the region 62 above the second conductive pad 30B is for reflecting green light and the total thickness of the dielectric layer 20 therein is about 700 angstroms. The thicknesses of the first dielectric film 201, the second dielectric film 202, and the third dielectric film 203 may be, for example, about 330 angstroms, 330 angstroms, and 40 angstroms, respectively. Different dielectric films with raised refractive indices may be formed by selecting different precursors or adjusting the ratio of precursors during the second mask operation.

[0048] In some embodiments, Fig. 6E , the region 63 above the third conductive pad 30C is used to reflect green light and the total thickness of the dielectric layer 20 therein is about 50 angstroms. The thicknesses of the first dielectric film 201, the second dielectric film 202, and the third dielectric film 203 may be, for example, about 20 angstroms, 20 angstroms, and 10 angstroms, respectively. Different dielectric films with raised refractive indices may be formed by selecting different precursors or adjusting the ratio of precursors during the third mask operation.

[0049] Therefore, in regions 61, 62, and 63, the thickness of the dielectric layer 20 is about 1500 angstroms, 700 angstroms, and 50 angstroms, respectively, and each region further includes a first dielectric film 201, a second dielectric film 202, and a third dielectric film 203 having refractive indices of, for example, 1.47, 1.7, and 1.8, respectively, the refractive index increasing from the bottom film to the top film of the dielectric layer 20. More precisely, as Fig. 6Ea In the display (from Fig. 6E ), a first conductive pad 30A and a second conductive pad 30B are placed above the metallization structure 50. The first dielectric film 201 has a first thickness T61 on the first conductive pad 30A and a second thickness T62 on the second conductive pad 30B, and the first thickness is different from the second thickness T62. The second dielectric film 202 has a third thickness T63 above the first conductive pad 30A and a fourth thickness T64 above the second conductive pad 30B, and the third thickness T63 is different from the fourth thickness T64. The third dielectric film 203 has a fifth thickness T65 above the first conductive pad 30A and a sixth thickness T66 above the second conductive pad 30B, and the fifth thickness T65 is different from the sixth thickness T66.

[0050] like Fig. 6F In some embodiments, the dielectric layer 20 includes a plurality of recesses 64 above the plurality of spaces 32 between each two adjacent conductive pads 30. In some embodiments, the recesses 64 may be formed by an etching operation. The recesses 64 may isolate the regions 61, 62, and 63 mentioned in the previous operation as previously described. Figure 5 The raised portion 21 and the edge portion 22 mentioned in FIG. In some embodiments, the thickness of the dielectric layer 20 at the bottom of the groove 64 is less than about 50 angstroms and thus may not substantially reflect visible light.

[0051] In some embodiments, the method for forming the dielectric film is not limited to PECVD, for example, the first dielectric film 201 and the second dielectric film 202 may be formed by CVD or PECVD, and the third dielectric film 203 is formed by ALD. Specifically, in some embodiments, the material of the first dielectric film 201 and the second dielectric film 202 is silicon oxide instead of aluminum oxide used in the third dielectric film 203. Therefore, in some embodiments, the density of the first dielectric film 201 or the second dielectric film 202 is less than the density of the third dielectric film 203.

[0052] like Figure 6Fa In the display, according to the FIG. 6A to FIG. 6F In the top view of the semiconductor structure formed by the operation shown in FIG. 1 , the raised portions 21R, 21G and 21B of the dielectric layer can reflect red light, green light and blue light respectively, and the raised portions 21R, 21G and 21B can be clearly distinguished by the edge portion 22 .

[0053] like Figure 6G , in some embodiments, multiple electrical connections 70 may be formed through each of the raised portions 21 of the dielectric layer 20 in multiple contact forming operations. Figure 6H , a conductive oxide layer 40 is formed over the dielectric layer 20. More precisely, each of the raised portions 21 may be covered by the conductive oxide layer 40, and an electrical connection 70 may connect the conductive oxide layer 40 with the conductive pad 30. In some embodiments, the conductive oxide layer 40 is an indium tin oxide (ITO) layer.

[0054] The reflective structures described herein can be integrated with a light emitting device, such as a micro OLED 42. The dielectric layer 20 is surrounded by an insulating layer 41 that is subsequently deposited to fill the gaps between adjacent dielectric layers 20. The micro OLED 42 can be placed above the insulating layer 41 and the reflective structure. In some embodiments, the conductive oxide layer 40 is in contact with the electrodes of the micro OLED 42. In some embodiments, as Fig.6I , light L from a micro OLED 42 enters the dielectric layer 20 of the reflective structure. More precisely, the light L may penetrate the dielectric layer 20 and be reflected by the conductive pad 30. As previously described, the thickness of the dielectric layer 20 is related to the wavelength reflected by the dielectric layer 20. In some embodiments, red light R, green light G, and blue light B may be reflected by the dielectric layer 20 having different thicknesses. In some embodiments, the source of the light L may be a light emitting layer placed higher than the reflective structure. For the purpose of clear demonstration, the difference between the thickness of each of the dielectric layers 20 is not drawn to scale. The thickness difference between each of the dielectric layers 20 may be microscopically tiny and thus the conductive oxide layer 40 on each of the discrete dielectric layers 20 may be in contact with the electrodes of the micro OLED 42.

[0055] refer to Fig. 7A , Fig. 7A The relationship between the total reflectivity of the dielectric layer and different incident wavelengths is shown. The total reflectivity of the reflective structure is compared under two conditions: one is that three dielectric films with a rising refractive index are formed in the order from the conductive pad 30 to the conductive oxide layer 40; the other is that three dielectric films with a falling refractive index are formed in the order from the conductive pad 30 to the conductive oxide layer 40. Line 81A refers to the total reflectivity of dielectric films with refractive indices of about 1.47, 1.7, and 1.8 stacked from bottom to top, while the total reflectivity of dielectric films with refractive indices of about 1.8, 1.7, and 1.47 stacked from bottom to top is referred to as line 81B. In the wavelength of visible light (about 380nm to 750nm), the total reflectivity of the reflective structure with a rising refractive index is higher than the total reflectivity of the reflective structure with a falling refractive index.

[0056] refer to Figure 7B , Figure 7B The relationship between the total reflectivity of the dielectric layer and different incident wavelengths is shown. The total reflectivity of the reflective structure is compared under two conditions: one is to form four dielectric films with a rising refractive index in the order from the conductive pad 30 to the conductive oxide layer 40; the other is to form four dielectric films with a falling refractive index in the order from the conductive pad 30 to the conductive oxide layer 40. Line 82A refers to the total reflectivity of dielectric films with refractive indices of about 1.5, 1.6, 1.7 and 1.8 stacked from bottom to top, while the total reflectivity of dielectric films with refractive indices of about 1.8, 1.7, 1.6 and 1.5 stacked from bottom to top is referred to as line 82B. In the wavelength of visible light, the total reflectivity of the reflective structure with more than three rising refractive indices is also higher than the total reflectivity of the reflective structure with a falling refractive index.

[0057] refer to Figure 7C , Figure 7C The relationship between the total reflectivity of the dielectric layer and different incident wavelengths is shown. The total reflectivity of the reflective structure is compared under three conditions: one is to form three dielectric films with ascending refractive indices in the order from the conductive pad 30 to the conductive oxide layer 40; another is to form three dielectric films with descending refractive indices in the order from the conductive pad 30 to the conductive oxide layer 40; and yet another is to form three dielectric films in a random refractive index arrangement other than ascending or descending order. Line 83A refers to the reflectivity of dielectric films with refractive indices of about 1.47, 1.7, and 1.8 stacked from bottom to top, while the reflectivity of dielectric films with refractive indices of about 1.8, 1.7, and 1.47 stacked from bottom to top is referred to as line 83B, and the reflectivity of dielectric films with refractive indices of about 1.7, 1.8, and 1.47 stacked from bottom to top is referred to as line 83C. In the wavelength of visible light, the total reflectivity of the reflective structure with a raised refractive index is not only higher than the total reflectivity of the reflective structure with a lowered refractive index, but also higher than the total reflectivity of the reflective structure with a random refractive index.

[0058] In the present disclosure, a reflective structure includes a dielectric layer on a metal substrate, wherein at least three dielectric films having refractive indices arranged in ascending order are stacked. Thus, the overall reflectivity of the reflective structure can be increased, and the uniformity requirements of the dielectric layer are relaxed.

[0059] In one exemplary aspect, a reflective structure is provided. The reflective structure includes: a metal substrate and a dielectric layer. The metal substrate has a first surface. The dielectric layer is placed on the first surface and has a first dielectric film, a second dielectric film, and a third dielectric film. The first dielectric film is placed on the first surface. The second dielectric film is placed on the first dielectric film. The third dielectric film is placed on the second dielectric film. The refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film.

[0060] In another exemplary aspect, a reflective structure is provided. The reflective structure includes: an interconnect structure, a first metal substrate, a second metal substrate, a first dielectric film, a second dielectric film, and a third dielectric film. The first metal substrate and the second metal substrate are above the interconnect structure. The first dielectric film has a first thickness on the first metal substrate and a second thickness on the second metal substrate. The first thickness is different from the second thickness. The second dielectric film is on the first dielectric film. The second dielectric film has a third thickness on the first metal substrate and a fourth thickness on the second metal substrate. The third thickness is different from the fourth thickness. The third dielectric film is on the second dielectric film. The third dielectric film has a fifth thickness on the first metal substrate and a sixth thickness on the second metal substrate. The fifth thickness is different from the sixth thickness. The refractive index of the first dielectric film is less than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is less than the refractive index of the third dielectric film.

[0061] In yet another exemplary aspect, a semiconductor structure is provided. The semiconductor structure includes a metallization structure, a plurality of conductive pads, and a dielectric layer. The plurality of conductive pads are above the metallization structure. The dielectric layer is on the metallization structure and covers the conductive pads. The dielectric layer includes a first dielectric film, a second dielectric film, and a third dielectric film. The first dielectric film is on the conductive pads. The second dielectric film is on the first dielectric film. The third dielectric film is on the second dielectric film. The refractive index of the first dielectric film is less than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is less than the refractive index of the third dielectric film.

[0062] The foregoing summarizes the structures of several embodiments so that those skilled in the art can better understand the aspects of the present disclosure. Those skilled in the art will appreciate that they can easily use the present disclosure as a basis for designing or modifying other manufacturing processes and structures for carrying out the same purposes and / or achieving the same advantages of the embodiments described herein. Those skilled in the art will also recognize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and modifications may be made herein without departing from the spirit and scope of the present disclosure.

[0063] Explanation of symbols

[0064] 10:Metal base

[0065] 20: Dielectric layer

[0066] 21: Raised part

[0067] 21B: Raised part

[0068] 21G: Raised part

[0069] 21R: Raised part

[0070] 22: Edge

[0071] 30: Conductive pad

[0072] 30A: First conductive pad

[0073] 30B: Second conductive pad

[0074] 30C: The third conductive pad

[0075] 31: Insulation layer

[0076] 32: Interval

[0077] 40: Conductive oxide layer

[0078] 41: Insulation layer

[0079] 42: Micro OLED

[0080] 50:Metalized structure

[0081] 61: Area

[0082] 62: Area

[0083] 63: Area

[0084] 64: Groove

[0085] 70: Electrical connection

[0086] 81A: Line

[0087] 81B: Line

[0088] 82A: Line

[0089] 82B: Line

[0090] 83A: Line

[0091] 83B: Line

[0092] 83C: Line

[0093] 101: First surface

[0094] 201: first dielectric film

[0095] 202: Second dielectric film

[0096] 202A: Sublayer

[0097] 202B: Sublayer

[0098] 202C: Sublayer

[0099] 203: third dielectric film

[0100] 300: Top surface

[0101] 310: Top surface

[0102] 501: substrate

[0103] 502: stacked layer

[0104] B: Blue light

[0105] G: Green light

[0106] L: Light

[0107] R: Red light

[0108] T1: Thickness

[0109] T2: Thickness

[0110] T61: First thickness

[0111] T62: Second thickness

[0112] T63: The third thickness

[0113] T64: Fourth thickness

[0114] T65: Fifth thickness

[0115] T66: Sixth thickness

[0116] W: Width

Claims

1. A reflective structure, comprising: a metal substrate having a first surface; a dielectric layer on the first surface, the dielectric layer comprising: a first dielectric film on the first surface; a second dielectric film on the first dielectric film; and a third dielectric film on the second dielectric film; an electrical connection that penetrates the dielectric layer and contacts the conductive pad; and a conductive oxide layer over the dielectric layer and in contact with the electrical connection; The refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film. 2 . The reflective structure according to claim 1 , wherein a material of the first dielectric film is the same as a material of the second dielectric film. 3 . The reflective structure according to claim 1 , wherein a material of the first dielectric film is different from a material of the third dielectric film. The reflective structure according to claim 1 , wherein an area of ​​the first dielectric film is larger than an area of ​​the metal substrate. The reflective structure of claim 1 , wherein the metal substrate is laterally surrounded by an insulating layer. The reflective structure according to claim 5 , wherein a portion of the insulating layer is covered by the first dielectric film. 7 . The reflective structure of claim 5 , wherein a top surface of the insulating layer is coplanar with a top surface of the metal substrate.

8. A reflective structure comprising: a first metal substrate and a second metal substrate over the interconnect structure; a first dielectric film having a first thickness on the first metal substrate and a second thickness on the second metal substrate, the first thickness being greater than the second thickness; a second dielectric film on the first dielectric film, the second dielectric film having a third thickness above the first metal substrate and a fourth thickness above the second metal substrate, the third thickness being greater than the fourth thickness; and a third dielectric film on the second dielectric film, the third dielectric film having a fifth thickness above the first metal substrate and a sixth thickness above the second metal substrate, the fifth thickness being greater than the sixth thickness; The refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film. 9 . The reflective structure of claim 8 , wherein the second dielectric film further comprises a plurality of sub-layers between the first dielectric film and the third dielectric film. 10 . The reflective structure according to claim 8 , wherein a material of the first dielectric film is silicon oxide and a material of the third dielectric film is aluminum oxide.

11. The reflective structure of claim 9, wherein the plurality of refractive indices of the plurality of sub-layers are in a range from 1.47 to 1.

8. 12 . The reflective structure of claim 9 , wherein a refractive index of a bottom portion of the sub-layer is smaller than a refractive index of a top portion of the sub-layer. 13 . The reflective structure according to claim 8 , wherein a density of the second dielectric film is smaller than a density of the third dielectric film. The reflective structure of claim 8 , wherein the surface roughness of the first metal substrate is less than 100 angstroms.

15. The reflective structure of claim 8, further comprising a groove isolating the stack of the first dielectric film and the second dielectric film into two raised portions. 16 . The reflective structure according to claim 15 , wherein a thickness of the first dielectric film at the bottom of the groove is less than 50 angstroms and is not covered by the second dielectric film.

17. A semiconductor structure comprising: Metallized structure; a plurality of conductive pads over the metallization structure; a dielectric layer on the metallization structure and covering the conductive pad, the dielectric layer comprising: a first dielectric film on the conductive pad; a second dielectric film on the first dielectric film; and a third dielectric film on the second dielectric film; a conductive oxide layer over the dielectric layer; and an electrical connection connecting the conductive oxide layer and the conductive pad; The refractive index of the first dielectric film is smaller than the refractive index of the second dielectric film, and the refractive index of the second dielectric film is smaller than the refractive index of the third dielectric film. 18 . The semiconductor structure of claim 17 , wherein the dielectric layer further comprises a groove above a space between two adjacent conductive pads.

19. The semiconductor structure of claim 17, wherein the dielectric layer further comprises a plurality of raised portions, and each of the raised portions has a thickness that is different from a thickness of an adjacent raised portion.

20. The semiconductor structure of claim 17, wherein the second dielectric film comprises a plurality of sub-layers, a refractive index of a bottom portion of the sub-layer being smaller than a refractive index of a top portion of the sub-layer.

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