TW584913B - Method of etching silicon substrate surface to increase light emission efficiency of device - Google Patents

Abstract

A kind of method of etching silicon substrate surface to increase the light emission efficiency of device is disclosed in the present invention. Before forming nanometer particle layer and the conduction layer, chemical etching is first used to remove the surface energy state or surface defect of silicon substrate, so as to reduce the non-radiative electron-hole recombination centers of the silicon substrate surface, and to increase the ratio of radiative electron-hole recombination of metal oxide silicon (MOS) emitting device such that the light emitting efficiency is greatly increased when the MOS structure generates light. In addition, the etching step also can cause nanometer scale surface structure and increase the collision probability between electron-hole pairs and phonons, so as to relatively increase the light emitting efficiency.

Description

584913 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to a metal-Oxide-Silicon Light Emitting Diode (MOSSLED) technology, and particularly to a method using a family name carved stone eve A method for improving the electro-optical efficiency of a metal oxide element on the surface of a substrate. [Previous technology] According to the metal oxide structure (M0S) was proposed by MοΠ, Pfann and Garrett in 1959, it was first used as a voltage control capacitor, 1970 B 0 1 e and Smith put forward the concept of charge coupling, and made charge-coupled device (Charge-Coupled Device, CCJ)), which is currently the key component of CCD cameras and digital cameras. In the 1980s, M 0 S has become a very important structure in integrated circuits (ICs). Complementary metal oxide semiconductors (composite raetal- The oxide-semiconductor (CMOS) system has become the most important element in very large-scale integrated circuits (VLSI) or very large-scale integrated circuits (uLSI). Even in solar cells, Mos is a highly regarded structure. Although the M 0 S structure plays a very important role in the field of electronics, since silicon semiconductors are an indirect bandgap, the electron holes directly require the participation of phonons to generate light. In order to meet the requirements of conservation of momentum, under normal circumstances, the probability of three particles of electrons, holes and phonons colliding together is very small, so the probability of direct recombination of electron holes to produce light is very small, making M0s possible to emit light. The situation is not bullish.

584913

V. Description of the invention (2) Then a kind of oxite luminescent diode using nano particles and nano structure was developed, so that silicon is not limited by the indirect energy gap, and the luminous efficiency of silicon is improved. 7 The basic principle lies in the application of quantum Mechanical tunneling ef feet. From the theoretical calculations of quantum mechanics, it is known that when the thickness of the oxide layer is as thin as a few nanometers (nm), the probability of electrons to tunnel will increase significantly, and this tunneling probability will increase with the forward bias. And the increase; but the oxide layer is not a conductor, so there is still a small voltage across the oxide layer, that is, the metal and the silicon semiconductor have different voltages, which causes the energy band of the silicon semiconductor to bend. If it is an N-type stone, under forward bias (metal is connected to a positive voltage, silicon semiconductor is connected to a negative voltage), near the interface between the oxide layer and the silicon semiconductor, the energy band of the silicon semiconductor is bent downward, so the potential energy of the electron is formed. (Potential well), and a large number of accumulated electrons, at this time there are a large number of holes from the metal end through the tunneling effect to reach the position of the potential well of this electron, so that a large number of electrons and holes can be recombined here (recombination ), And easily collide with phonons to emit photons; if it is P-type silicon, the principle of generating photons by electrical excitation can also be deduced by analogy. However, since the light emitting diode is on the surface of the silicon substrate, the recombination of electrons and holes is still affected by the nonradiative recombination center. The nonradiative recombination center contains impurities , Defects, or surface energy levels, etc., a reduces the proportion of radiative S-combination; these non-radiative recombination centers provide additional recombination paths for electrons and holes, and because of the non-radiative recombination centers, The lifetime of carriers (electrons and holes) will be significantly shortened. So reduce;

584913 V. Description of the invention (3) The sing-radiation recombination center can increase the proportion of radiation recombination, which can further improve the luminous efficiency. In view of this, the present invention is directed to the above-mentioned shortcomings, and proposes an innovative concept of a method for improving the luminous efficiency of a device by etching the surface of a silicon substrate, which is not limited by the indirect energy gap of silicon in order to effectively improve the structure of gold-oxygen silicon. Luminous efficiency. [Summary of the Invention] The main object of the present invention is to provide a method for improving the luminous efficiency of a device by etching the surface of a silicon substrate, which can reduce the compound center of non-radiative electron holes on the surface of the silicon substrate, so that The compound ratio of the radiant electron hole is increased without being limited by the indirect energy gap of silicon, so it can achieve the effect of greatly improving the luminous efficiency of the device. Another object of the present invention is to provide a method for improving the luminous efficiency of a device by etching the surface of a silicon substrate, which can form a nano-scale surface structure on the surface of the silicon substrate. This nano-structure can make electron holes limited to one nanometer. In the area of meters, the probability of an electron hole pair colliding with a phonon is greatly increased, and the luminous efficiency is further enhanced. Another object of the present invention is to provide a method for improving the luminous efficiency of a device by etching the surface of a silicon substrate. The method can use mature processes and equipment on the existing semiconductor manufacturing factory lines to perform semiconductor processes, so the process is simple and the manufacturing cost is low. And can be directly combined with the advantages of the IC industry. In order to achieve the above-mentioned object, the present invention is to etch a silicon substrate with a high-concentration etching solution on the surface of a clean semiconductor silicon substrate to remove the non-radiative compound center on the surface of the silicon substrate and form the same at the same time. Nano

584913 V. Description of the invention (4) Structure, clean the silicon substrate after completion; then, sequentially form a nano particle layer and a conductive layer on the surface of the silicon substrate in order to complete the operation of the gold-oxygen silicon light-emitting device. In the following, detailed descriptions will be made with specific embodiments and accompanying drawings to make it easier to understand the purpose, technical content, features and functions of the present invention. [Embodiment] The present invention uses a technology of etching the surface of a silicon substrate to enable a gold-oxide-silicon structure (MOS) to efficiently generate photons by electrically exciting light to achieve the effect of improving the luminous efficiency of a MOS device. Recombination by electrons and electricity is affected by non-radiative recombination centers such as impurities, surface defects, and surface energy levels, which reduces the proportion of radiative recombination. Participation of 'significantly shortens the lifetime of the carrier containing electrons and holes. The lifetime of the carrier can be expressed by the following formula: 山 山 JL + i 山 ... 丄 Among them 3: the mechanism of radiation recombination, non The effect of defects in radiative recombination 'A is the influence of impurities in non-radiative recombination, ^ the influence of the surface energy level of non-radiative recombination center; it can be known that all non-radiative recombination centers will let the carrier live Period shortened. As far as silicon substrates are concerned, through the experimental measurement of the lifetime, the invention has found that the carrier lifetime of the cz Shixi substrate is within 丨 0 // s, while the lifetime of the FZ Shixi substrate can reach 6〇 // s , Even 1 ms; visible

IH 584913 V. Description of the invention (5) The non-radiative recombination center has a great influence on the additional recombination of electrons and holes. Because the luminescence of the golden silicon 70 luminescence is on the surface of the silicon substrate, the surface energy, and the surface defects have a great impact. 'Experimental measurement of life found that under no surface energy level and surface defects (that is, inside the crystal) The carrier lifetime is 1 ms. However, under the influence of the surface energy level, the lifetime is shortened to 6 p, which has a bad influence on the luminescence of the gold oxide silicon light emitting diode. In view of this, when the metal oxide silicon light emitting device is manufactured by the present invention, the surface of the silicon substrate, such as chemical etching, is first processed to reduce the influence of the surface energy level or the surface defect, so that the light emission of the metal oxide light emitting device can be effectively improved. effectiveness. The first (a) to the first (d) diagrams are cross-sectional views of the structure of each step in the fabrication of a gold-oxide-silicon light-emitting device according to the present invention. As shown in the figure, first, a semiconductor silicon substrate 10 is provided. As shown in the figure, it is cleaned through a standard cleaning process; then, a high-concentration potassium hydroxide (KOH) solution, sodium hydroxide (NaOH) solution, or Tetramethy lammonium hydroxide (Tetramethy lammonium hydroxide) is used. Hydroxide (TMAH) solution and other etching solutions. This clean semiconductor silicon substrate 10 is chemically etched. The etching time is determined by the concentration of the etching solution, usually between 10 and 40 seconds. The depth is not more than 50 nanometers (nm). In this 14-step step, the non-radiative composite center on the surface of the stone evening substrate 10 is removed, and a nanostructure is formed on the surface of the stone evening substrate 10. The size of the meter structure is between 1 nanometer and 300 nanometers. After the chemical etching step is completed, the silicon substrate is washed again with deionized water and blow dried. Then, the conventional conventional silica nanoparticle solution was diluted to reduce the nanoparticle concentration, and the spin coating method was used on the silicon substrate.

sun Page 10 584913 V. Description of the invention (6) A nano particle layer 12 is formed on the surface as shown in the first (b) diagram; after the nano particle layer 12 is formed, the silicon substrate 10 is dried and removed. Organic solvents. Then, as shown in the first (c) diagram, a thin oxide layer 1 4 ′ is vapor-deposited on the surface of the nano-particle layer 丨 2, and then the surface of the alumina layer 丨 4 is again plated by the evaporation method. Applying silver or silver paint 'see the first (d) figure to form a conductive layer 16, and so far, the fabrication of the gold-oxide-silicon light-emitting element is completed. The material of the silicon substrate used above can also be selected from the group consisting of germanium, silicon germanium, silicon carbide, and other indirect energy gap materials; on the other hand, in the step of etching the silicon substrate 10 In addition to chemical etching, gaseous etching or ion etching can also be used. In the present invention, when a metal oxide silicon light-emitting device is manufactured, a silicon substrate is etched first with a KOH solution, and the etching solution will start from a surface defect first. Therefore, the etching solution can be used to remove the surface energy level or the surface defect. In a suitable time, the good crystal area of the silicon substrate is not yet etched; and the etching time depends on the concentration of the etching solution, but it is better to be able to remove the surface energy level or surface defects without seriously etching the good crystal area of the silicon substrate. So far, the spirit of the present invention has been described. The following principles are verified and demonstrated by several experimental examples, and those skilled in the art can also obtain sufficient knowledge by referring to the description of these examples and implement them. The chemical etching of a + conductor silicon substrate is carried out by using a 45% solution of hydroxide in hydrogen concentration, and the etching time is 30 seconds. At this time, the structures before and after the axis engraving are compared. It is shown that // is a microphotograph of the atomic force of the silicon substrate before and after etching. Before the etching, the surface of the silicon substrate is very flat. As shown in the second picture, 584913 Five silicon, description of the invention (7) ___ The surface height difference of the silicon substrate is only a few angstroms. (^ Some parts of the surface of the substrate have been etched. After the k-face is etched, the depth is about 100 A, as shown in the third figure. The two parts are collapsing and present a very flat surface. This is because of benignization. The two are not etched. The j-frame structure is the most fragile & the place begins: two = from the Shixi substrate grid defect or the surface is subject to foreign Atomic shadow ;, · = where the weak point is) 'the etched part of the surface of the silicon substrate' ;; θ (, where there are many surface energy levels, many surface energy levels or surface defects, because: a Reason 1 makes non-radiative compounding: rupture removal 'according to compounding Increasing the proportion, so that the luminous effect is restored; :: ... Therefore, the radiation type :: money can be removed in addition to removable surface energy & nanometer-level surface structure, this ^ ^, can also be limited to-柰In the meter area, because the electric mpf electrons and holes are easily added by phonons, the particles and holes are already together. The collision of the three particles of the soson is now expected to be: electrons, holes and phonons. Collision, so the probability of a collision between the hole and the phonon is enhanced. For the sake of improvement, it also makes the luminous efficiency relatively. Please refer to the fourth figure, the direct-knowing effect on the luminous efficiency. = The liquid crystal engraving time can help the luminous efficiency pole II = Seeing that the flat part of the etching time surface is also harmed. 'The Shi Xi substrate table is shown in the fifth figure. The relationship between the intensity and current of the pot, The light that can be achieved, the blue line is the relationship diagram of the luminous efficiency versus the electric steam = the intensity of the electric current versus the wide machine. The invention is significantly enhanced. V. Description of the invention (8) The light intensity makes the efficiency increase under the current. , The output light can reach more than i times, the fifth picture is displayed at 1 〇 〇in long sub-efficiency has exceeded 10 μ; WW, and at 20 m A, the corresponding part of the external denier, most of the light is not b. This light intensity is calculated only from the edge of the silver paint The light that has not been collected is covered by silver paint, that is, it is 10 to 3 in other directions. In the sixth diagram, the members and / or devices are therefore the true external quantum rate = the spectrum in this diagram It shows that the luminous light t / of this metal oxide light emitting device is not a light squat of impurities, but an electron hole radiation type gastric complex octahedral energy level of a broken substrate. It is confirmed that the above-mentioned chemical money has not increased. Know 1 This metal oxide silicon light-emitting element measurement 'is found the current 载: load: (electron, hole) life time < Actually, due to non-radiative renunciation 哉: the sub-life time is shortened' ⑹ seventh picture: There is a radiation compound; the lifetime is not affected by the current, 1Ϊ: heterodyne] = indicates that the radiation compound plays a very important angle. The radiation compound has been greatly reduced under chemical etching, so the gold Table, the luminous efficiency of the light-emitting element is greatly improved. In addition, "metal oxide silicon" therefore, the present invention can indeed reduce the non-radiation hole composite 1 core on the surface of the silicon substrate, so that the radiation electron electron compound ratio of the metal oxide silicon light emitting device is south, without being affected by silicon. The indirect energy gap is limited, and the second is the effect of greatly improving the luminous efficiency of the device. And because the fabrication process of this metal oxide 2 2 $ MOS structure is close to that of the traditional MOS structure, and it is on the silicon wafer, it can be completely straightened with the current integrated circuit, making the silicon wafer not only There are applications in electronic products, including 584913. V. Description of the invention (9) As a high-efficiency light-emitting element, the monolithic integration of electronic chips and light-emitting elements can further expand the application range of silicon wafers and materials. In addition, the MOS structure and manufacturing process of the alumina element of the present invention are quite simple and the production cost is low. X can be directly combined with 1C industry, so it has considerable practicability. The above-mentioned embodiments are only for explaining the technical ideas and characteristics of the present invention, and the purpose is to enable those skilled in the art to tolerate and implement them. When it is not possible to limit it too much ⑽ ^ Revealed by the spirit of 1 is the change or modification of the "Jushi 3 Temple, still numb ,; ¾ 盍 is within the scope of the patent of the present invention. 1 5 shall / 1¾ [Illustration of drawing number] 10 Semiconductor silicon substrate 1 2 Nai Rice particle layer 14 Alumina layer 1 6 Metal layer end of chapter

584913 Brief description of the drawings The first (a) to the first (d) diagrams are cross-sectional views of the structure of each step in the fabrication of the metal-oxide-silicon light-emitting device. The second figure is an atomic force micrograph of the surface of the silicon substrate of the present invention before chemical etching. The third picture shows the atomic force micrograph of the silicon substrate surface after chemical etching according to the invention. The fourth picture shows the effect of the etching time of the potassium hydroxide solution used on the invention on the luminous intensity.

The fifth graph is a graph of luminous intensity and luminous efficiency versus current that can be achieved through the present invention, where the red line is a graph of luminous intensity versus current and the blue line is a graph of luminous efficiency versus current. The sixth figure is a light emission spectrum of the metal oxide light emitting device of the present invention. The seventh figure is a relationship diagram of the carrier lifetime and current of the metal oxide light emitting device of the present invention.

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Claims (1)

584913 VI. Application Patent Scope 1 · A method for improving the luminous efficiency of a device by etching the surface of a silicon substrate, including the following steps: providing a clean semiconductor silicon substrate; etching the silicon substrate with an appropriate concentration of etching solution to remove the silicon substrate Or reducing the non-radiative compound center on the surface of the silicon substrate and forming a nanostructure on the surface of the silicon substrate; forming a nanoparticle layer on the surface of the silicon substrate; and forming a conductive layer on the surface of the nanoparticle layer Floor. 2. The method according to item 1 of the scope of patent application, wherein the clean semiconductor silicon substrate is cleaned by a cleaning step. 3. The method according to item 1 of the scope of patent application, wherein the etching solution is selected from the group consisting of a bell hydroxide solution, a sodium hydroxide solution, and a tetramethylammonium hydroxide (TMAH) solution. 4. The method according to item 1 of the scope of patent application, wherein in the step of etching the silicon substrate, the etching time for etching the silicon substrate is between 10 and 40 seconds. 5. The method according to item 1 or 4 of the scope of patent application, wherein the time for etching the silicon substrate is determined according to the concentration of the etching solution. 6. The method according to item 1 of the scope of patent application, wherein in the step of chemically etching the silicon substrate, the etching depth is not more than 50 nm. 7. The method according to item 1 of the scope of patent application, wherein the size of the nano structure formed on the surface of the silicon substrate is between 1 nanometer and 300 nanometers. Page 16 584913 VI. Scope of Patent Application 8 • The method described in item 1 of the scope of patent application, wherein the nanoparticle layer is formed by a spin coating method. 9. The method as described in item 1 of the scope of patent application, wherein the nanoparticle layer is composed of nanoparticle of crushed nanoparticle. 1 0. The method according to item 1 of the scope of patent application, wherein in the step of etching the silicon substrate, the etching method used is selected from the group consisting of chemical etching, gas etching and ion etching. 1 1 · The method as described in item 1 of the scope of patent application, wherein the non-radiative composite center system includes impurities, surface defects and surface energy levels. 1 2 The method according to item 1 of the scope of patent application, wherein in the step of cleaning the silicon substrate, cleaning is performed with deionized water. 1 3. The method according to item 1 of the scope of patent application, wherein after the step of forming the nanoparticle layer, the method further comprises a step of drying and removing an organic solvent. 14 · The method according to item 1 of the scope of patent application, wherein the conductive layer is formed by a vapor deposition method. 15 · The method according to item 1 of the scope of patent application, wherein the conductive layer is made of silver or silver paint. 16 · The method according to item 1 of the scope of patent application, wherein the material of the silicon substrate can be selected from the group consisting of silicon, germanium, silicon germanium, silicon carbide, and other indirect bandgap materials. Page 17