TW201242084A - Chip structure for enhancing light extraction efficiency and process using the same - Google Patents

Abstract

A chip structure for enhancing light extraction efficiency and a process using the same are disclosed. The chip structure includes an epitaxial layer and a substrate. The substrate is disposed on the bottom of the epitaxial layer. Some surfaces of the substrate are formed with a first notch and a second notch. The depth of the first notch is equal to or not equal to that of the second notch so that some surfaces of the substrate are formed with the shape of a stepped structure.

Description

201242084

TW7471PA VI. Description of the Invention: [Technical Field] The present invention relates to a wafer structure and a process thereof, and more particularly to a wafer structure and a process for improving light extraction efficiency. [Prior Art] A Light-Emitting Diode (LED) wafer mainly emits light by converting electric energy into light energy. The main constituent material of the light-emitting diode wafer is a semiconductor in which a positively charged hole ratio is called a P-type semiconductor, and a negatively charged electron ratio is called an N-type semiconductor. A p-type semiconductor is connected to the N-type semiconductor to form a PN junction. When a voltage is applied across the positive and negative terminals of the light-emitting diode chip, the electrons are combined with the holes. When the electrons are combined with the holes, they are emitted in the form of light. Light-emitting diode chips have been widely used in screen backlights, desk lamps, large display panels, traffic signs, vehicle brake lamps, and power supplies due to their long life, low temperature, and high energy efficiency. Indicator lights, etc. Conventional light sources have gradually been replaced by light-emitting diode chips. However, the refractive index of a semiconductor substrate of a light-emitting diode wafer is usually larger than the refractive index of air, so that the incident light rays larger than the total reflection angle cause total reflection at the substrate/air interface, thus causing most of the light to be It is limited to the inside of the substrate and cannot be taken out, resulting in poor light extraction efficiency. SUMMARY OF THE INVENTION The present invention relates to a wafer structure for improving light extraction efficiency and 201242084.

The TW747IPA is manufactured so that incident light is not confined inside the substrate and cannot be removed. According to an aspect of the invention, a wafer structure for improving light extraction efficiency is proposed. The wafer structure includes an epitaxial layer and a substrate. The substrate is disposed at the bottom of the epitaxial layer. A portion of the surface of the substrate has a first score and a second score. The depth of the first score is equal to or not equal to the depth of the second score so that a portion of the surface of the substrate forms a stepped structure. According to an aspect of the invention, a wafer process for improving light extraction efficiency is proposed. This wafer process includes the following steps. Forming an epitaxial layer on a substrate; forming a first indentation and a second indentation on a portion of the surface of the substrate. The depth of the first indentation is equal to or not equal to the depth of the second indentation to make a portion of the substrate The surface forms a first stepped structure; and the base is split to form a section 'this section connects the first stepped structure. In order to better understand the above and other aspects of the present invention, the following detailed description of the preferred embodiments, together with the drawings, will be described in detail as follows: [Embodiment] The wafer structure for improving the light extraction efficiency of this embodiment And its process is to change the topography of the surface of the substrate, for example to form the same or different depths of the score, so that part of the surface of the substrate forms at least one stepped structure. Therefore, the light incident on the inside of the substrate is less likely to cause total reflection at the interface between the stepped structure and the air', and the light originally confined to the inside of the substrate is effectively taken out: = the light extraction efficiency of the light-emitting diode wafer is improved. The following is a detailed description of various embodiments. The embodiments are intended to be illustrative only and to limit the scope of the invention. 4 201242084

TW7471PA FIRST EMBODIMENT Referring to Figures 1A and 1B, a cross-sectional view of a wafer structure for enhancing light extraction efficiency in accordance with an embodiment is shown. The wafer structure i includes a slave day layer 120 and a substrate 130. The substrate 130 is disposed at the bottom of the epitaxial layer 120. A portion of the surface of the substrate 130 has a first score 131 and a second score 132. The depth H1 of the first score 131 may be equal to the depth H2 of the second score 132 such that a portion of the surface of the substrate 130 forms a first stepped structure 110. In another embodiment, the depth H1 of the first score 131 may not be equal to the depth H2 of the second score 132. Therefore, the depth of the score is equal or not. Referring to Figure 1A, the substrate 130 has an upper surface i3a, a lower surface 130b, and a side surface 130c. The epitaxial layer 12 is located on the upper surface 13A. The first step structure lio is connected between the upper surface 13〇a and the side surface 13〇c, and the bottom surface of the first notch 131 is spaced apart from the upper surface 13〇a by a distance substantially equal to the bottom surface of the second notch 132. The distance from the surface 13〇a, ie H1 = H2. Therefore, the partial upper surface 13〇a and the partial side surface 130c of the substrate 13 are formed with a step structure resistant to total reflection so that the light L incident on the inside of the substrate 13 is not easily at the interface of the first step structure 11 and the air. The phenomenon of total reflection occurs. Further, referring to the figure, unlike FIG. 1A, the first stepped structure lio is connected between the lower surface 13〇b between the side faces 13〇c and the bottom surface of the first notch 131 is spaced apart from the lower surface 13〇b. The distance is substantially equal to the distance of the bottom surface of the second score 132 from the lower surface 13〇b, ie Ηι== belly. Thus, a portion of the lower surface of the substrate 130 is a bird and a portion of the side (10). A step structure of primary anti-reflection is formed to make light incident on the inside of the substrate 13 5 5 201242084

l The phenomenon that the entire reverse line L of the W/4/lhW 110 and the interface of the air is not easy to be emitted by the first step structure. The second embodiment shows that the lift light extraction effect according to an embodiment is that a part of the surface of the wafer structure 102# substrate 13 is except for the first score (3) and the second score 132. The surface also has a second score 135 and a fourth score 136. The depth H3 of the third score 135 is equal to or not equal to the depth H4 of the fourth score 136 such that another portion of the surface of the substrate (10) forms a second stepped structure 112. In an embodiment, the second stepped structure 11 is connected between the upper surface 13a and the side surface i3〇c as shown in FIG. 1A, and the second stepped structure 112 is connected between the lower surface 130b and the side surface 130c. The bottom surface of the third score 135 is spaced from the lower surface 130b by a distance substantially equal to the distance of the bottom surface of the fourth score 136 from the lower surface 130b, that is, H3 = H4. Therefore, the partial upper surface 130a, the partial lower surface i30b, and the partial side surface 13〇c of the substrate 13A are formed with a plurality of anti-total reflection step structures, so that the light L incident on the inside of the substrate 1 is not easy for the first and second steps. Structure 11 全, 112 and air interface C is totally reflected. THIRD EMBODIMENT Referring to Figures 3A and 3B, there are shown cross-sectional views of a wafer structure for enhancing light extraction efficiency in accordance with an embodiment. The wafer structure 2 includes an epitaxial layer 220 and a substrate 230. The substrate 230 is disposed on the epitaxial layer 220 201242084

At the bottom of the TW7471PA, a portion of the surface of the substrate 230 has a first score 231 and a second score 232. The depth H1 of the first score 231 is not equal to the depth H2 of the second score 232, that is, H1 is off H2, so that A portion of the surface of the substrate 230 forms a first stepped structure 210. Referring to Figure 3A, the substrate 230 has an upper surface 230a, a lower surface 230b, and a side surface 230c. The epitaxial layer 220 is located on the upper surface 230a. The first stepped structure 210 is connected between the upper surface 230a and the side surface 230c' and the bottom surface of the first score 231 is spaced apart from the upper surface 230a by a distance substantially equal to the distance of the bottom surface of the second score 232 from the upper surface 230a, ie H1 turns off H2. Therefore, the partial upper surface 230a and the partial side surface 230c of the substrate 230 form a continuous step structure resistant to total reflection, so that the light L incident on the inside of the substrate 230 is not easily totally reflected at the interface A of the first step structure 210 and the air. phenomenon. In one embodiment, the lower surface 230b of the substrate 230 of Figure 3A is, for example, a roughened surface. The roughened surface prevents a phenomenon in which a part of the light L incident on the inside of the substrate 230 is totally reflected twice or more so that the light L can also be scattered outward through the roughened lower surface 230b, thereby improving the light extraction efficiency. In addition, please refer to FIG. 3B 'different from FIG. 3A , the first step structure 210 is connected between the lower surface and the side surface 230 c ′ and the bottom surface of the first scribe 231 is spaced apart from the lower surface 230 b by a distance not equal to the second The bottom surface of the score 232 is spaced from the lower surface 230b by a distance 'ie H1 妾 H2. Therefore, the partial lower surface 230b of the substrate 230 and the partial side surface 230c form a continuous step structure resistant to total reflection, so that the light L incident on the inside of the substrate 230 is not easily totally reflected at the interface A of the first step structure 210 and the air. phenomenon. 201242084 1 w /^/ ιγα In one embodiment, the upper surface 230a of the substrate 230 of Figure 3B is, for example, a roughened surface. The roughened surface prevents the partial light L incident on the inside of the substrate 230 from being totally reflected twice or more, so that the light L can also be scattered outward through the roughened upper surface 230a, thereby improving the light extraction efficiency. Fourth Embodiment Referring to Figure 4, there is shown a cross-sectional view of a wafer structure for enhancing light extraction efficiency in accordance with an embodiment. Different from the third embodiment described above, a portion of the surface of the substrate 230 of the wafer structure 202 has a third score 235 and a fourth portion in addition to the first score 231 and the second score 232. Scoring 236. The depth H3 of the third score 235 is not equal to the depth H4 of the fourth score 236 such that another portion of the surface of the substrate 230 forms a second stepped structure 212. In one embodiment, the first stepped structure 210 is coupled between the upper surface 230a and the side surface 230c, as shown in FIG. 3A, and the second stepped structure 212 is coupled between the lower surface 230b and the side surface 230c, and the third score is The bottom surface of 235 is spaced apart from the lower surface 230b by a distance not equal to the distance of the bottom surface of the fourth score 236 from the lower surface 230b, that is, H3 is referred to as H4. Therefore, the partial upper surface 230a, the partial lower surface 230b, and the partial side surface 230c of the substrate 230 form a plurality of continuous step structures resistant to total reflection, so that the light L incident on the inside of the substrate 230 is not easy for the first and second step structures 210, The phenomenon of total reflection occurs at the interface between 212 and air. The wafer process will be described by taking the wafer structure of Fig. 1A as an example to form a portion of the upper surface 130a of the substrate 130 to form a first stepped structure 110. Similarly, the first stepped structure 110 of FIG. 1B can also use the following steps of 201242084 & to make a portion of the lower surface ostrich of the substrate 30 form a first stepped structure 110. Of course, the first indentation 131 and the second indentation 132 having different depths in the third and third crucibles can also use the following steps to form an I1 white ladder structure on a part of the upper surface leg or a part of the lower surface of the substrate 130. 110 'The only difference is that the position of the score is different. Please refer to FIG. 5 to FIG. 5C for a schematic cross-sectional view showing a wafer process for improving light extraction efficiency according to an embodiment. The wafer process includes the following steps: ν (1) ~ (3). Step (1) forms an epitaxial layer (10) on a substrate 130. The step (2) forms a first score ΐ3ι and a second second score 132 on a portion of the surface of the substrate 130. The depth Η of the first score ΐ3ι is equal to or not equal to the depth Η of the second score 132 so that a part of the surface of the base 13〇 forms a first stepped structure 11〇. The bottom is 13 〇 to form a section and a section structure. Please refer to the 2β, when the completion of the rotation (2), "= a third score 135 and - the fourth score 136 on the other surface of the substrate (10), the depth 第三3 of the third score 135 is equal to or not equal to the fourth The depth of the score 136 is such that the surface of the other portion of the substrate 13 is formed into a second stepped structure 112. The above-mentioned section 13〇d is the partial side surface 130c of the substrate 13〇. The partial upper surface _ and the partial side surface 130c of the 130 form a step structure resistant to total reflection so that the light L incident on the inside of the substrate 130 is less likely to be totally reflected at the interface A of the first step structure 11 空气 and the air. In one embodiment, the substrate 130 is a sapphire substrate or a carbonized stone substrate. The material of the substrate 130 is not (5), and the refractive index is also different. The substrate 9 201242084 1 W/4/im 130 has a large refractive index, that is, total reflection. The angle is small, so that when the light is incident on the inside of the substrate 130 at the same angle, if the incident angle is larger than the total reflection angle, the phenomenon of total reflection inside the substrate 130 will become easier. For example, when the refractive index of the air is the same as that of the substrate 130 Refractive index When the ratio is 0·5, the total reflection angle is about 30. Referring to FIG. 5A, the epitaxial layer 120 is, for example, Vapor Phase Epitaxy (VPE) or Liquid Phase Epitaxy (Liquid Phase Epitaxy; LPE) or Metal Organic Vapor Epitaxy (M0VPE) is formed on the substrate 130. High-brightness illumination is generally performed by quaternary (AlGalnP aluminum phosphide) and gallium nitride (GaN) epitaxial layers. Luminescent material of the diode. The quaternary (AlGalnP) epitaxial layer can be used on a handheld electronic device (such as a mobile phone), which can generate red, orange or yellow light, and a gallium nitride (GaN) epitaxial layer can be produced. Blue light and green light can be used for white light illumination. Next, referring to FIG. 5B, the first notch 131 and the second notch 132 are formed on a part of the surface of the substrate 130 by, for example, wet chemical etching or laser etching. The third score and the fourth score are also formed in the same manner. The depths of the first score 131 and the second score 132 may be equal or unequal. In an embodiment, when the etching time is different, the first The depth of the score 131 and the second score 132 are not equal. In addition, in FIG. 3A When the first notch 231 and the second notch 232 of different depths are adjacent to each other, a continuous stepped structure may be formed on a part of the surface of the substrate 230 (for example, the upper surface 230a). Also in FIG. 4, when etching When the times are different, the depths of the third score 235 and the fourth score 236 are not equal. In addition, when the third score 235 and the fourth score 236 of different depths are adjacent to each other, a continuous step may be formed. 201242084

TW7471PA ladder, "is part of the surface of the substrate 230 (for example, the lower surface 23〇b). Next, referring to FIGS. 5B and 5C, the lower surface i30b of the base 130 is cut, for example, by the tip end of the cutter I40 to form a respective cut surface 137, and then the base 13〇 is split along the dividing lines u, L2 to form a predetermined The section of the direction is 13〇d. Since the thickness of the base 13 is smaller than the thickness of the recesses of the first score 131 and the second score 132, the cross section will be connected to the bottom surface of the corresponding score to form the split shown in FIG. 5C. Wafer: 100 〇 口 口 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片 晶片Part of the surface of the substrate forms a stepped junction. Therefore, the light incident on the inside of the substrate is not easy to be reversed (four) at the step structure/air=face, thereby effectively limiting the original light to the inside of the bottom to improve the light emission. The light extraction efficiency of the polar body wafer. In addition, the upper surface or the lower surface of the substrate may be a roughened surface to prevent the partial light of the illuminating portion from being totally reflected twice or more, so that the first line may also be outward through the roughened upper surface or the lower surface. Scattering' further enhances light extraction efficiency. As described above, the present invention has been disclosed in the above preferred embodiments, and the present invention is not limited thereto. Those skilled in the art to which the present invention pertains are more versatile and refinement in the spirit and scope of the present invention. Therefore, the scope of the protection scope of the present invention is defined. Postpartum Appendices 201242084 1 w /η / ir/\ [Simplified Schematic Description] Figs. 1A and 1B are schematic cross-sectional views showing a wafer structure for improving light extraction efficiency according to an embodiment. Fig. 2 is a cross-sectional view showing the structure of a wafer for improving light extraction efficiency according to an embodiment. 3A and 3B are schematic cross-sectional views showing a wafer structure for improving light extraction efficiency according to an embodiment. Fig. 4 is a cross-sectional view showing the structure of a wafer for improving light extraction efficiency according to an embodiment. 5A to 5C are schematic cross-sectional views showing a wafer process for improving light extraction efficiency according to an embodiment. [Main component symbol description] 100, 102, 200, 202: wafer structure 110, 210: first step structure 112, 212: second step structure 120, 220: epitaxial layer 130, 230: substrate 131, 231: first Scoring 132, 232: second score 130a, 230a: upper surface 130b, 230b: lower surface 130c, 230c: side 130d: section 135, 235: third score 136, 236: fourth score 137, 138 :cut surface

S 12 201242084

TW7471PA 140 : Tool A, B, C: Interface HI, H2, H3, H4: Depth L: Light U, L2: Split line 13 5

Claims (1)

201242084 TW7471PA 1 1 VII. Patent Application Range: 1. A wafer structure for extracting light extraction efficiency, the wafer structure comprising: a crystal layer; and a substrate 'disposed on the bottom of the layer' a first-scratch and a second-notch having a depth equal to or equal to a depth of the second score such that a portion of the surface of the substrate forms a first stepped structure. 2. The wafer structure of claim 2, wherein the substrate has an upper surface, a lower surface, and a side surface, the crystal layer is located on the upper surface / the first step structure is connected to the lower surface And the distance from the bottom surface of the first score of the first score to the lower surface is equal to or not equal to the distance of the bottom surface of the second score from the lower surface. 3. The wafer structure of claim 2, wherein the substrate has an upper surface, a lower surface, and a side surface, wherein the crystal layer is located on the upper surface, and the first step structure is coupled to the upper surface The side surface, and the bottom surface of the first score is spaced from the upper surface by a distance equal to or not equal to the distance of the bottom surface of the second score from the upper surface. 4. The wafer structure of claim 1, wherein another portion of the surface of the substrate further has a third score and a fourth score. The depth of the third score is equal to or not equal to the fourth The depth of the score is such that a surface of another portion of the substrate forms a second stepped structure. The wafer structure of claim 4, wherein the substrate has an upper surface, a lower surface, and a side surface, the epitaxial layer is located on the upper surface, the first step structure is coupled to the upper surface and the Between the sides of 201242084 TW7471PA, and the bottom surface of the first-scratch is at a distance equal to or not equal to the distance of the bottom surface of the first score from the upper surface, the second step structure is connected to the lower surface and The distance between the sides of the third indentation and the bottom surface of the third indentation is equal to or not equal to the distance of the bottom surface of the fourth indentation from the lower surface. 6. The wafer structure of claim 1, wherein the substrate is a sapphire substrate or a carbonized stone substrate. 7. The wafer structure of claim 1, wherein the epitaxial layer comprises a gallium nitride (GaN) layer. 8. A wafer process for improving light extraction efficiency, the wafer process comprising: forming an epitaxial layer on a substrate; marking and - second scoring on a portion of the surface of the substrate (4) a depth of a score equal to or not equal to a deep production of the second indentation such that a portion of the surface of the substrate forms a first stepped structure; and a structure is configured to split the bottom of the substrate to form a section, the section connecting the first step = · as claimed The wafer process described in item 8 and the method of the second indentation include wet chemical-etching 1 such as applying for a patent, item 8 _^^: into; f three-notch and - fourth-scratch in the The depth of the other/third notch of the substrate is equal to or not equal to the surface of the fourth indentation such that the other portion of the surface is formed - the second stepped structure is read, as described in claim 10 Wafer process, where 15 § 201242084 ' TW7471PA forms the third score and the fourth score includes wet chemical etching or laser etching.