Gallium nitride device forming method and gallium nitride device

Abstract

The invention relates to the technical field of semiconductor manufacturing, in particular to a gallium nitride device forming method and a gallium nitride device. The invention provides a method for forming a gallium nitride device. The method comprises the following steps: providing a substrate to be etched; the substrate to be etched at least comprises a substrate layer, a first conductive type gallium nitride layer, a quantum well layer and a second conductive type gallium nitride layer which are stacked; performing dry etching on the substrate to be etched; in an etching gas environment, through inductive coupling plasma etching, an etching groove is formed in the to-be-etched substrate, so that the to-be-etched substrate forms a preliminary etching device; wherein chemical corrosion and physical bombardment act together; repairing the damage; and in a repairing gas environment, through inductively coupled plasma etching, enabling the preliminary etching device to form a target etching device. Wherein chemical corrosion plays a leading role. According to the method, the problem that the non-radiative recombination probability is increased due to the fact that the side wall of a product structure is damaged and side wall defects are aggravated when the gallium nitride device is etched by a dry method can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a gallium nitride device forming method and a gallium nitride device. Background Art

[0002] With the development of display technology, LED display technology is ushering in a leapfrog development, among which the new generation of display technology represented by Mirco-LED (micrometer light emitting diode) technology has become a typical representative.

[0003] Growing demand for mobile displays is driving the adoption of miniaturized pixels in next-generation display technologies. This shift has evolved from traditional liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs) to Micro LED technology, which offers significant advantages, including higher resolution, reduced energy consumption, longer lifetime, higher brightness, and faster response time. In particular, gallium nitride (GaN)-based Micro LEDs have become a key technology in display technology and visible light communication (VLC) research. However, as chip size decreases, especially for ultra-small chips that are critical in high-definition displays, declining efficiency poses a major challenge to the commercial viability of Micro LEDs. In the traditional top-down LED manufacturing process, dry etching using inductively coupled plasma (ICP) is mainly used, which causes plasma-related damage to the device sidewalls. As device size decreases, this damage becomes more pronounced due to the increased perimeter-to-area ratio, exacerbating the size effect. Sidewall damage increases the Shockley-Read-Hall (SRH) recombination rate, significantly reduces the internal quantum efficiency and increases the peak current density, which adversely affects display performance. Historically, methods using wet etching and deposition of passivation layers have been used to mitigate these negative effects. In particular, the use of wet etching after dry etching has been shown to significantly reduce non-radiative recombination defects, which is one of the most direct and effective strategies to mitigate etching damage and minimize size-related effects. However, alkaline wet etching lacks uniformity and has limited compatibility with nitride semiconductor processes, which may pose potential risks to other functional layers, resulting in reduced chip yield. In addition, the roughness and increased dangling bond density produced by wet etching on the sidewalls of nitride LEDs reduce chip reliability. Recently, atomic layer etching and neutral beam etching have shown promise due to their low-damage characteristics. Unfortunately, these methods have extremely low etching rates and high costs, limiting their scalability and practical application in future display technologies. Although early strategies focused on mitigating the sidewall damage effects in Micro LED devices, previous studies mainly analyzed this damage from the perspective of final device performance, largely ignoring the underlying mechanisms and physical models. Therefore, in order to effectively advance Micro LED technology towards large-scale commercialization, a deep understanding of the form and impact of sidewall damage is urgently needed. This insight must be combined with the development of compatible industrial strategies to effectively minimize surface defects to fully realize the full potential of Micro LED technology.

[0004] In the preparation process of Mirco-LED devices, the film layer needs to be etched to form the required shape. Dry etching is currently a mainstream processing technology for forming the specified required shape of the film layer of Mirco-LED devices. Especially for devices made of gallium nitride materials. Compared with other processing technologies such as wet etching, dry etching technology has many advantages such as good macroscopic morphology of the side wall of the product structure, high etching rate, high selectivity, and high anisotropy. However, dry etching can also cause damage to the side wall of the product structure, aggravate the side wall defects, increase the probability of non-radiative recombination, and thus lead to a decrease in luminous efficiency. With the development of LED display technology, the size of light-emitting chips is getting smaller and smaller, and this defect will be further amplified.

[0005] Therefore, a solution is needed to solve the problem that dry etching of GaN devices will damage the side walls of the product structure, aggravate the side wall defects, and increase the probability of non-radiative recombination. Summary of the invention

[0006] Therefore, the present invention provides a gallium nitride device forming method and a gallium nitride device to solve the problem that dry etching of gallium nitride devices may damage the sidewalls of the product structure, aggravate the sidewall defects, and increase the probability of non-radiative recombination.

[0007] The present invention provides a method for forming a gallium nitride device, comprising the following steps: providing a substrate to be etched; the substrate to be etched at least comprises: a substrate layer, a first conductive type gallium nitride layer, a quantum well layer and a second conductive type gallium nitride layer in a stacked arrangement; the first conductive type gallium nitride layer and the second conductive type gallium nitride layer have opposite conductive types; dry etching the substrate to be etched; in an etching gas environment, by inductively coupled plasma etching, an etching groove is formed in the substrate to be etched, so that the substrate to be etched forms a preliminary etching device; the etching groove extends from the second conductive type gallium nitride layer to the substrate layer, penetrates the quantum well layer, and the bottom of the groove goes deep into the first conductive type gallium nitride layer; damage repair; in a repair gas environment, by inductively coupled plasma etching, the preliminary etching device forms a target etching device. Wherein, the etching rate in the process of the damage repair is less than the etching rate in the process of the dry etching of the substrate to be etched.

[0008] In one aspect of the present invention, the damage repair step includes the following steps: forming a second etching mask on the side of the second conductive type gallium nitride layer away from the substrate layer, the second etching mask exposing the etching groove; in an inductively coupled plasma etcher, introducing the repair gas into a process chamber, using the second etching mask as a mask, inductively coupled plasma etching the preliminary etching device; removing the second etching mask to form the target etching device.

[0009] In one aspect of the present invention, in the damage repair step, the repair gas includes Cl2; and the flow rate of the repair gas is 50 sccm to 110 sccm.

[0010] In one aspect of the present invention, in the damage repair step, the process conditions also include: plasma source power is 100W~400W; bias power is 10W~50W; DC bias is 20V~60V; pressure in the process chamber is 1mT~10mT; cooler temperature is -10℃~10℃; the material of the second etching mask includes SiO2, SiN, metal or photoresist.

[0011] In one aspect of the present invention, the step of dry etching the substrate to be etched includes the following steps: forming an initial first etching mask on the side of the second conductive type gallium nitride layer away from the substrate layer; patterning the initial first etching mask to form a first etching mask; the first etching mask exposes part of the surface of the second conductive type gallium nitride layer; in an inductively coupled plasma etcher, introducing the etching gas into a process chamber, using the first etching mask as a mask, and inductively coupling plasma etching the substrate to be etched; removing the first etching mask to form the preliminary etching device.

[0012] In one aspect of the present invention, in the step of dry etching the substrate to be etched, the etching gas includes a main etching gas and an auxiliary etching gas; the main etching gas includes Cl2, and the flow rate of the main etching gas is 20sccm to 80sccm; the auxiliary etching gas includes BCl3, Ar, N2 or He; the flow rate of the auxiliary etching gas is 10sccm to 40sccm;

[0013] In one aspect of the present invention, in the damage repair step, the process conditions also include: plasma source power is 300W~800W; bias power is 100W~200W, and the ion source bias power is less than half of the plasma source power; DC bias is 100V~200V; pressure in the process chamber is 1mT~10mT; cooler temperature is -10℃~10℃; the material of the first etching mask includes SiO2, SiN, metal or photoresist.

[0014] In one aspect of the present invention, the gallium nitride device formation method further includes the following steps: using a purge gas to purge the target etching device to remove residual etching gas and repair gas; the step of purging the target etching device includes several purge cycles; each of the purge cycles includes two purge stages; the two purge stages include: a first stage of continuously introducing the repair gas into the process chamber and a second stage of continuously evacuating the chamber.

[0015] In one aspect of the present invention, the purge cycle is repeated 8 to 12 times; the first stage time is 2s to 4s; and the second stage time is 2s to 4s.

[0016] The present invention also provides a gallium nitride device, which is manufactured using the gallium nitride device forming method provided by the present invention.

[0017] The beneficial effects of the present invention are as follows:

[0018] The gallium nitride device forming method provided by the present invention first etches a substrate to be etched by inductively coupled plasma etching in an etching gas environment to obtain a preliminary etched device; then continues the inductively coupled plasma etching in a repairing gas environment. In the environment without the repairing gas, the degree of inductively coupled plasma etching slows down, and the damaged layer formed in the etching step can be effectively removed to obtain a surface with relatively lower roughness, so that the surface properties of the device after etching and repair are better, and a device surface with a good shape can be obtained, thereby reducing side wall defects and preventing the probability of non-radiative recombination from increasing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the local structure of a gallium nitride device after etching the gallium nitride device using a dry etching method;

[0021] Figure 2 A schematic diagram of a process for forming a gallium nitride device according to an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of a partial structure of a substrate to be etched during a method for forming a gallium nitride device according to an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of a device state in which an initial first etching mask is formed during a method for forming a gallium nitride device according to an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of a device state in which a first etching mask is formed during a method for forming a gallium nitride device according to an embodiment of the present invention;

[0025] Figure 6It is a schematic diagram of a device state of forming a preliminary etched device during a method for forming a gallium nitride device according to an embodiment of the present invention;

[0026] Figure 7 It is a schematic diagram of a device state of forming a target etching device during a method for forming a gallium nitride device according to an embodiment of the present invention;

[0027] Figure 8 A schematic diagram of a partial structure of a gallium nitride device formed by a method for forming a gallium nitride device according to an embodiment of the present invention;

[0028] Fig. 9 A curve diagram showing the variation of the DC bias voltage with the increase of the process gas flux in the gallium nitride device forming method according to an embodiment of the present invention;

[0029] Fig.10 A curve diagram showing the variation of the DC bias voltage with the increase of the plasma source power in the gallium nitride device forming method according to an embodiment of the present invention;

[0030] Fig.11 A graph showing the increase in photoluminescence intensity (PL) as the plasma source power increases in a method for forming a gallium nitride device according to an embodiment of the present invention;

[0031] Fig.12 A curve diagram showing the variation of the DC bias voltage with the increase of the bias power in the gallium nitride device forming method according to an embodiment of the present invention;

[0032] Fig.13 FIG. 1 is a graph showing the variation of the DC bias voltage with the increase of the chamber pressure in the gallium nitride device forming method according to an embodiment of the present invention.

[0033] Fig.14a An electron microscope image of the local morphology of a gallium nitride device formed by a gallium nitride device forming method according to an embodiment of the present invention before a damage repair step is performed;

[0034] Fig.14b for Fig.14a A magnified view of a local edge of a device;

[0035] Fig.14c This is an electron microscope image of the local morphology of a gallium nitride device formed by a gallium nitride device forming method according to an embodiment of the present invention after a damage repair step is performed.

[0036] Description of reference numerals:

[0037] 100 - substrate layer; 200 - first conductivity type gallium nitride layer; 300 - quantum well layer; 400 - second conductivity type quantum well layer; 500 - initial first etching mask; 510 - first etching mask; 520 - second etching mask; damaged layer 600; A - etching gas; B - repair gas. DETAILED DESCRIPTION

[0038] refer to Figure 1 , a method for dry etching gallium nitride devices. The gallium nitride device after etching, as shown in the figure, includes a stacked arrangement of: a substrate layer 100, a first conductive type gallium nitride layer 200, a quantum well layer 300 and a second conductive type gallium nitride layer 400; the first conductive type gallium nitride layer and the second conductive type gallium nitride layer have opposite conductivity types. The etching groove formed after dry etching extends from the second conductive type gallium nitride layer 400 to the substrate layer 100, penetrates the quantum well layer 300, and the bottom of the groove goes deep into the first conductive type gallium nitride layer 200. As shown in the figure, the gallium nitride device after etching will leave a damaged layer 600 on the surface of the etching groove. The inventor has found that the damaged layer 600 is naturally formed during the etching process due to the corrosion of gallium nitride by dry etching gas; the damaged layer 600 causes damage to the side wall of the device, which aggravates the side wall defects and increases the probability of non-radiative recombination.

[0039] In order to solve the problem that dry etching of gallium nitride devices may damage the side walls of the product structure, aggravate the side wall defects, and increase the probability of non-radiative recombination, the present invention provides a method for forming a gallium nitride device and a gallium nitride device.

[0040] The method for forming a gallium nitride device provided by the present invention comprises the following steps: providing a substrate to be etched; the substrate to be etched at least comprises: a substrate layer, a first conductive type gallium nitride layer, a quantum well layer and a second conductive type gallium nitride layer which are stacked; the first conductive type gallium nitride layer and the second conductive type gallium nitride layer have opposite conductive types; dry etching the substrate to be etched; in an etching gas environment, by inductively coupled plasma etching, forming an etching groove in the substrate to be etched, so that the substrate to be etched forms a preliminary etching device; the etching groove extends from the second conductive type gallium nitride layer to the substrate layer, penetrates the quantum well layer, and the bottom of the groove goes deep into the first conductive type gallium nitride layer; damage repair; in a repair gas environment, by inductively coupled plasma etching, the preliminary etching device forms a target etching device.

[0041] The gallium nitride device provided by the present invention is manufactured using the gallium nitride device forming method provided by the present invention.

[0042] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In the description of the present invention, it should be noted that the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0043] Example 1

[0044] refer to Figure 2 ,as well as Figure 3-Figure 8 This embodiment provides a method for forming a gallium nitride device, comprising the following steps:

[0045] A substrate to be etched is provided; the substrate to be etched comprises at least: a substrate layer 100, a first conductive type gallium nitride layer 200, a quantum well layer 300 and a second conductive type gallium nitride layer 400 which are stacked.

[0046] The first conductive type gallium nitride layer 200 and the second conductive type gallium nitride layer 400 have opposite conductive types; for example, in different embodiments, when the first conductive type gallium nitride layer 200 is a P-type doped semiconductor layer, the second conductive type gallium nitride layer 400 is an N-type doped semiconductor layer; conversely, when the first conductive type gallium nitride layer 200 is an N-type doped semiconductor layer, the second conductive type gallium nitride layer 400 is a P-type doped semiconductor layer. In this embodiment, the first conductive type gallium nitride layer 200 is an N-type doped semiconductor layer, and the second conductive type gallium nitride layer 400 is a P-type doped semiconductor layer.

[0047] The substrate to be etched is dry-etched; in an etching gas A environment, an etching groove is formed in the substrate to be etched by inductively coupled plasma etching, so that the substrate to be etched forms a preliminary etching device; the etching groove extends from the second conductive type gallium nitride layer 400 to the substrate layer 100, passes through the quantum well layer 300, and the bottom of the groove goes deep into the first conductive type gallium nitride layer 200.

[0048] Damage repair: In the repair gas B environment, the preliminary etching device is formed into a target etching device through inductively coupled plasma etching.

[0049] The etching rate during the damage repair process is lower than the etching rate during the dry etching of the substrate to be etched.

[0050] The gallium nitride device formation method provided in this embodiment first etches the substrate to be etched by inductively coupled plasma etching in an etching gas A environment to obtain a preliminary etched device, and then continues inductively coupled plasma etching in a repair gas B environment. The degree of inductively coupled plasma etching is slowed down, and the damaged layer formed in the etching step can be effectively removed to obtain a surface with relatively lower roughness, so that the surface properties of the device after etching and repair are better, and a device surface with a good shape can be obtained, thereby reducing side wall defects and preventing the probability of non-radiative recombination from increasing.

[0051] For further reference, Figure 7 In this embodiment, the damage repair step includes the following steps:

[0052] forming a second etching mask 520 on a side of the second conductive type gallium nitride layer 400 away from the substrate layer, wherein the second etching mask 520 exposes the etching groove;

[0053] In the inductively coupled plasma etcher, the repair gas B is introduced into the process chamber, and the preliminary etching device is etched by inductively coupled plasma using the second etching mask 520 as a mask.

[0054] Afterwards, refer to Figure 8 , remove the second etching mask 520 to form the target etching device.

[0055] In this way, the second conductive type gallium nitride layer 400 is covered by the second etching mask 520 to expose the etching groove, so that the inductively coupled plasma etching process continued in the repair gas B environment only occurs on the etching groove, and the damaged layer 600 (position reference 1) on the side wall and bottom of the etching groove is accurately etched. Figure 1 ), the damaged layer 600 can be effectively etched away, and the residual etching gas A can be prevented from further corroding the second conductive type gallium nitride layer 400 in the subsequent process, thereby avoiding further deepening of the damaged layer 600.

[0056] Furthermore, in this embodiment, in the damage repair step,

[0057] The repair gas includes Cl2;

[0058] The flow rate of the repair gas B is 50 sccm to 110 sccm.

[0059] In the repairing stage, in order to slow down the corrosion of the second conductive type gallium nitride layer 400, the inductively coupled plasma etching process is dominated by gas chemical corrosion, so the gas environment in the process only contains Cl2.

[0060] refer to Fig. 9 , Fig. 9This is a curve showing the change of DC bias as the process gas flux (i.e., the flux of repair gas B) increases. As can be seen from the curve, the DC bias value is low between 40sccm and 120sccm. The lower the DC bias, the smaller the damage. Taking into account the error range and the redundancy of the operation process, the flux of repair gas B in the repair process is selected to be 50sccm to 110sccm. If the flow rate of repair gas B is lower than 50sccm, the gas may not be dissociated and the process cannot be carried out; and the plasma energy may be too low to effectively remove the etched damaged layer. If the flow rate of repair gas B is higher than 110sccm, the plasma energy may be too high, causing new damage. Therefore, when the gas flux is selected within the range of 50sccm to 110sccm, a balance can be achieved between effectively removing damage and avoiding adding new damage.

[0061] Furthermore, in this embodiment, in the damage repair step, the process conditions also include:

[0062] The plasma source power is 100W~400W.

[0063] refer to Fig.10 , Fig.10 The curve of DC bias voltage as the plasma source power increases is shown in Figure 2. It is generally believed that under the premise that other conditions remain unchanged, the lower the source power, the lower the bombardment of the plasma on the material of the device to be etched. However, this method takes the collision between ions into consideration and obtains the minimum DC bias voltage window through experimental design, such as Fig.10 As shown in the figure, by observing the overall curve, the DC bias is the lowest when the source power is 400W, so the window is around 400W; the reason for choosing the interval of <400W is that the greater the source power, the greater the energy of the ions themselves. Under the premise that the DC bias difference is not too large, the greater the ion energy, the greater the damage to the material. Therefore, in the selection of this parameter, we added Fig.11 The photoluminescence (PL) test further narrows the window of source power through PL test. It is generally believed that the smallest DC bias voltage will cause the least etching damage to the material. However, the source power determines the energy carried by the ions after the process gas is dissociated. Even if the DC bias voltage is at the lowest value, a larger source power will still cause etching damage. Finally, the sample is tested for photoluminescence (PL) after etching. Fig.11 As shown in the figure, the balance point between low DC bias and low source power was found, and a more ideal plasma source power was obtained.

[0064] The bias power is 10W to 50W. The DC bias is 20V to 60V. During the plasma etching process, a negative DC voltage is formed on the electrode (wafer) surface due to the mobility difference between electrons and ions. Specifically, the mass of electrons is much smaller than the mass of ions. Therefore, under the action of the RF electric field, electrons can quickly move to the electrode surface and accumulate, causing the electrode surface to be negatively charged, and eventually forming a negative DC bias between the electrode and the plasma, which is referred to as the DC bias in this article.

[0065] refer to Fig.12 , Fig.12 The curve graph shows the change of DC bias voltage with the increase of bias power. The DC bias voltage is proportional to the bias power. Theoretically, the lower the bias power, the lower the required bias power. It can be seen from the curve that the DC bias voltage is proportional to the bias power, so it is hoped that the bias power is as low as possible. Therefore, choosing a bias power range of 10W to 50W can strike a balance between ensuring the operation of process equipment and avoiding adverse effects on equipment caused by excessive voltage.

[0066] The pressure in the process chamber is 1mT~10mT.

[0067] refer to Fig.13 , Fig.13 is a curve diagram showing the change of DC bias voltage with increasing chamber pressure. Fig.13 As shown, within a certain gas flux range, the lower the pressure, the lower the DC bias, so the pressure is selected to be 1mT to 10mT, and a lower DC bias can be selected, thereby causing less damage to the gallium nitride of the second conductive type gallium nitride layer 400. If it is lower than 1mT, the pressure is too low and may cause the process gas to fail to dissociate and the equipment to fail to work; if it is higher than 10mT, the pressure is too high and affects the uniformity. Therefore, the pressure is selected to be within the range of 1mT to 10mT, which can strike a balance between ensuring the dissociation of the process gas and ensuring uniformity.

[0068] The cooler temperature is -10℃~10℃.

[0069] The material of the second etching mask includes SiO2, SiN, metal or photoresist.

[0070] Furthermore, in this embodiment, the step of dry etching the substrate to be etched includes the following steps:

[0071] refer to Figure 4 , forming an initial first etching mask 500 on a side of the second conductive type gallium nitride layer 400 away from the substrate layer 100;

[0072] refer to Figure 5, patterning the initial first etching mask 500 to form a first etching mask 510; the first etching mask 510 exposes a portion of the surface of the second conductive type gallium nitride layer 400;

[0073] refer to Figure 6 In the inductively coupled plasma etcher, in the etching gas A environment, the first etching mask 510 is used as a mask, and the substrate to be etched is etched by inductively coupled plasma; in this process, an etching groove is formed, and a damaged layer 600 is naturally formed on the surface of the etching groove;

[0074] Figure 6 Not shown, the first etching mask 510 is removed to form the preliminary etching device.

[0075] Furthermore, in this embodiment, in the step of dry etching the substrate to be etched,

[0076] The etching gas includes a main etching gas and an auxiliary etching gas;

[0077] The main etching gas includes Cl 2。

[0078] The flow rate of the main etching gas is 20 sccm to 80 sccm.

[0079] The auxiliary etching gas includes BCl3, Ar, N2 or He.

[0080] The flow rate of the auxiliary etching gas is 10 sccm to 40 sccm.

[0081] The material of the first etching mask 510 includes SiO 2 , SiN, metal or photoresist.

[0082] During dry etching, the main purpose is to form etching grooves of target size and structure, which mainly require speed and precision. Therefore, etching gas A selects the main etching gas and auxiliary etching gas for etching. If the flow rate of the corresponding gas is too low, it will affect the plasma density, thereby affecting the etching rate of the damaged layer. It may take a longer repair time to achieve the same effect, which will extend the process time. If the flow rate is too high, it may exceed the range of the equipment flow meter and the equipment will not work. The selection of the main etching gas and the auxiliary etching gas and the corresponding parameter range can ensure a balance between a shorter process time and meeting the equipment working conditions.

[0083] Furthermore, in this embodiment, in the damage repair step, the process conditions also include:

[0084] The plasma source power is 300W to 800W;

[0085] The bias power is 100W to 200W, and the ion source bias power is less than half of the plasma source power;

[0086] DC bias voltage is 100V~200V;

[0087] The pressure in the process chamber is 1mT to 10mT;

[0088] The cooler temperature is -10℃~10℃;

[0089] The material of the first etching mask includes SiO2, SiN, metal or photoresist.

[0090] Furthermore, in this embodiment, the method for forming a gallium nitride device further includes the following steps:

[0091] Using a purge gas to purge the target etching device to remove residual etching gas A and repair gas B;

[0092] By removing the etching gas A and repair gas B involved in the target device surface through purging gas, it is possible to prevent the gas from further corroding gallium nitride in the subsequent process, avoid further damage, and ensure that the device surface shape of the target etched device is in good condition.

[0093] The step of purging the target etching device includes a plurality of purging cycles; each of the purging cycles includes two purging stages;

[0094] The two purge stages include: a first stage of continuously introducing the repair gas into the process chamber and a second stage of continuously evacuating the chamber. Relatively good device morphology effects can be achieved through multiple purge cycles and the first and second stages in each purge cycle.

[0095] Furthermore, in this embodiment, the purge cycle is repeated 8 to 12 times; the first stage time is 2s to 4s; and the second stage time is 2s to 4s. If the cycle is repeated too few times, the purge may not be thorough, resulting in the process gas or byproducts remaining on the device surface not being completely removed, so that the device continues to be corroded after the process is completed; if the cycle is repeated too many times, although it will not affect the device, it will cause waste of production capacity. Therefore, the purge cycle is repeated 8 to 12 times, which can strike a balance between ensuring that the device surface is cleaned and avoiding waste of production capacity.

[0096] To further explain the gallium nitride device forming method of the present invention, a specific implementation process is provided as follows:

[0097] The device used in this process is an inductively coupled plasma etcher. The device has independent control functions for source RF power and bias RF power; process gas flow is controlled by a mass flow meter; the pressure chamber is controlled by a molecular pump and a mechanical pump; the sample is controlled by a back helium system and a chiller; and the DC bias voltage can be read through the software interface.

[0098] like Figure 3 As shown, a substrate to be etched is provided. In this process, the substrate to be etched is a gallium nitride epitaxial wafer, including a substrate layer 100, a first conductive type gallium nitride layer 200, a quantum well layer 300, and a second conductive type gallium nitride layer 400. The first conductive type gallium nitride layer 200 is an N-type doped semiconductor layer; the second conductive type gallium nitride layer 400 is a P-type doped semiconductor layer.

[0099] like Figure 4 As shown, an initial first etching mask 500 is formed on the surface of the gallium nitride epitaxial wafer, and the material of the initial first etching mask 500 is SiO2.

[0100] like Figure 5 As shown, the initial first etching mask 500 is patterned, and the patterning adopts photolithography and etching technology to expose the GaN epitaxial material that needs to be etched to form an etching groove. After this step is completed, a first etching mask 510 with an etching barrier pattern is formed on the surface of the epitaxial material.

[0101] like Figure 6 As shown, the dry etching step is the main etching step in the gallium nitride formation method, and its purpose is to etch the substrate to be etched to a target depth, form an etching groove, and define the etching morphology.

[0102] The main etching gas used in the main etching step is Cl2 with a flow rate of 50 sccm, and the auxiliary etching gas is BCl3 with a flow rate of 20 sccm. In this step, chemical corrosion and physical bombardment work together.

[0103] The plasma source power used in the main etching step is 500W, and the bias power is 180W. Generally, the bias power is set to be less than half of the source power.

[0104] The DC bias voltage during the main etching step is 130V.

[0105] The chamber pressure during the main etching step process is 3mT.

[0106] The cooler temperature during the main etching step process is 0°C.

[0107] The first etch mask 510 is then removed.

[0108] like Figure 7As shown, the etching repair step aims to remove the damaged layer 600 generated in the main etching step. This step will also cause etching damage, but the damage is much smaller than that in the main etching step.

[0109] Before the etching step, after the etching repair step is completed and before the sample is transferred out of the vacuum chamber, the sample surface is purged to remove the residual process gas between the devices and prevent the gallium nitride material from continuing to corrode after it is transferred out of the device.

[0110] The repair gas used in the etching repair step is Cl2, with a flow rate of 50sccm to 110sccm, and no auxiliary etching gas. Since physical bombardment is more likely to cause damage, this step is dominated by chemical corrosion. Since etching damage is mostly caused by physical bombardment, chemical corrosion can reduce etching damage and obtain devices with better morphology.

[0111] The plasma source power used in the etching repair step is 100W-400W, and the bias power is 10W-50W.

[0112] During the etching repair process, the DC bias voltage is controlled at 20V to 60V.

[0113] The chamber pressure during the etching repair process is 1mT to 10mT.

[0114] The cooler temperature during the etching repair process is -10°C to 10°C.

[0115] Finally, a purge process is performed to purge the target etched device after the damage repair step using a purge gas. The purge process is performed for 10 cycles, each cycle consisting of two stages: the first stage is to continuously introduce nitrogen for 3 seconds, and the second stage is to continuously evacuate the vacuum for 3 seconds.

[0116] To demonstrate the actual effect of this embodiment, refer to Figure 14a-Figure 14c .Depend on Fig.14a and Fig.14b It can be seen that before the etching repair step, the edge of the device side / device trench side layer structure is unclear and rough, which is caused by etching damage. Fig.14c It can be seen that after the etching repair step, the device side / device groove side structure has a clear edge, small roughness, and good morphology. It can be seen that after the method of Example 1 is formed, a device surface with a good shape can be obtained, thereby reducing the defects of the side wall and preventing the probability of non-radiative recombination from increasing.

[0117] Specifically, high-resolution transmission electron microscopy (TEM) was used to study the MESA array before and after repair to investigate the effect of sidewall etch damage on the brightness of the chip's "good area" and to verify the effect of the repair technology on the chip's sidewalls. Fig.14a , Fig.14b As shown in the figure, the edge of the MESA prepared using conventional ICP technology was imaged by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) to show significant changes within about 50nm of the sidewall etching area. The multiple quantum wells (MQWs) of the LED epilayer were blurred by high-energy ion etching, the originally clear and steep well-barrier interface disappeared, and the element distribution of this functional layer became random. An amorphous layer of about 2nm thick appeared at the edge of the sidewall, indicating that the etching damage not only destroyed the single crystal integrity of the sidewall surface, but also affected the lattice and element distribution depth of the light-emitting layer. This local sidewall morphological change weakened the carrier confinement ability of the MQW, thereby reducing the radiative recombination rate. It is worth noting that the electron blocking layer (EBL) located above the quantum well also showed similar morphological damage to the MQWs, indicating that the integrity was damaged within a depth of 50nm at the sidewall edge. This is the main reason for the sharp drop in the sidewall brightness profile observed in the unrepaired chip. More importantly, the damage to the EBL enhances the electron mobility in this area and dominates the large amount of carrier leakage. The damaged EBL forms a low-resistance "parallel circuit" at the edge of the original diode configuration, attracting carriers away from radiative recombination occurring in the good region. These carriers are directed to the sidewall regions with high defect density, resulting in leakage current and non-radiative recombination. The reduced carrier blocking capability of the EBL and the lateral carrier concentration gradient of the chip work together to attract carriers that would otherwise undergo radiative recombination in the good region. This process explains the significant reduction in brightness of the good region observed in chip brightness imaging.

[0118] Example 2

[0119] This embodiment provides a gallium nitride device, which is manufactured using the gallium nitride device forming method provided in the above-mentioned embodiment 1.

[0120] The gallium nitride device provided in this embodiment is formed by the gallium nitride device forming method of embodiment 1. First, in an etching gas environment, the substrate to be etched is etched by inductively coupled plasma etching to obtain a preliminary etched device; then, in a repair gas environment, the inductively coupled plasma etching is continued. In the repair gas environment, the degree of inductively coupled plasma etching is slowed down, and the damaged layer formed in the etching step can be effectively removed, and a surface with relatively lower roughness can be obtained, so that the surface properties of the device after etching and repair are better, and a device surface with a good shape can be obtained, thereby reducing the defects of the sidewalls and preventing the probability of non-radiative recombination from increasing.

[0121] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for forming a gallium nitride device, characterized in that: The following steps are involved: A substrate to be etched is provided; the substrate to be etched comprises at least a stacked arrangement of: a substrate layer, a first conductive type gallium nitride layer, a quantum well layer, and a second conductive type gallium nitride layer; the first conductive type gallium nitride layer and the second conductive type gallium nitride layer have opposite conductive types; Dry etching the substrate to be etched; in an etching gas environment, by inductively coupled plasma etching, forming an etching groove in the substrate to be etched, so that the substrate to be etched forms a preliminary etching device; the etching groove extends from the second conductive type gallium nitride layer to the substrate layer, penetrates the quantum well layer, and the bottom of the groove goes deep into the first conductive type gallium nitride layer; wherein chemical corrosion and physical bombardment act together; Damage repair; in a repair gas environment, the preliminary etched device is formed into a target etched device by inductively coupled plasma etching; wherein chemical corrosion plays a leading role.

2. The method for forming a gallium nitride device according to claim 1, characterized in that: The damage repair step includes the following steps: forming a second etching mask on a side of the second conductive type gallium nitride layer away from the substrate layer, wherein the second etching mask exposes the etching groove; In an inductively coupled plasma etcher, the repair gas is introduced into a process chamber, and the preliminary etching device is etched by inductively coupled plasma using the second etching mask as a mask; The second etching mask is removed to form the target etching device.

3. The method for forming a gallium nitride device according to claim 2, characterized in that: In the damage repair step, the repair gas includes Cl2; The flow rate of the repair gas is 50 sccm to 110 sccm.

4. The method for forming a gallium nitride device according to claim 2, characterized in that: In the damage repair step, the process conditions also include: The plasma source power is 100W~400W; Bias power is 10W~50W; DC bias voltage is 20V~60V; The pressure in the process chamber is 1mT to 10mT; The cooler temperature is -10℃~10℃; The material of the second etching mask includes SiO2, SiN, metal or photoresist.

5. The method for forming a gallium nitride device according to claim 1, characterized in that: The step of dry etching the substrate to be etched comprises the following steps: forming an initial first etching mask on a side of the second conductive type gallium nitride layer away from the substrate layer; Patterning the initial first etching mask to form a first etching mask; the first etching mask exposes a portion of the surface of the second conductive type gallium nitride layer; In an inductively coupled plasma etcher, the etching gas is introduced into a process chamber, and the substrate to be etched is etched by inductively coupled plasma using the first etching mask as a mask; The first etching mask is removed to form the preliminary etching device.

6. The method for forming a gallium nitride device according to claim 5, characterized in that: In the step of dry etching the substrate to be etched, the etching gas includes a main etching gas and an auxiliary etching gas; The main etching gas includes Cl2; The flow rate of the main etching gas is 20 sccm to 80 sccm; The auxiliary etching gas includes BCl3, Ar, N2 or He; The flow rate of the auxiliary etching gas is 10 sccm to 40 sccm; The material of the first etching mask includes SiO2, SiN, metal or photoresist.

7. The method for forming a gallium nitride device according to claim 6, characterized in that: In the damage repair step, the process conditions also include: The plasma source power is 300W to 800W; The bias power is 100W to 200W, and the bias power of the plasma source is less than half of the power of the plasma source; DC bias voltage is 100V~200V; The pressure in the process chamber is 1mT to 10mT; The cooler temperature is -10℃~10℃; The material of the first etching mask includes SiO2, SiN, metal or photoresist.

8. The method for forming a gallium nitride device according to claim 1, characterized in that: The following steps are also included: Using a purge gas to purge the target etching device to remove residual etching gas and repair gas; The step 44 of purging the target etching device includes a plurality of purging cycles; Each of the purge cycles comprises two purge stages; The two purge stages include: a first stage of continuously introducing the repair gas into the process chamber and a second stage of continuously evacuating the chamber.

9. The method for forming a gallium nitride device according to claim 8, characterized in that: The purge cycle is repeated 8 to 12 times; The first stage lasts for 2s to 4s; The second stage time is 2s to 4s.

10. A gallium nitride device, characterized in that: The gallium nitride device is manufactured using the gallium nitride device forming method according to any one of claims 1 to 9.

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