Ash photoresist removing method for aluminum etching

Abstract

An ashing photoresist removing method for aluminum etching comprises the steps that firstly, a wafer after aluminum etching is completed is placed in a process chamber of ashing equipment, the wafer comprises a semiconductor substrate, an aluminum layer and a photoresist layer which are stacked in sequence, and the photoresist layer is used as a mask in the aluminum layer etching process; step 2, introducing ashing gas into the process chamber so as to enable the pressure in the process chamber to reach a preset pressure; step 3, stopping introducing the ashing gas into the process chamber so as to reduce the pressure in the process chamber; wherein the step 2 and the step 3 are executed circularly to form a pressure pulse, so that the residual etching gas on the surface of the wafer is removed. According to the method, the ventilation step and the ventilation stopping step are circularly executed to form the pressure pulse, residual etching gas on the surface of the wafer is removed through the pressure pulse, and aluminum corrosion caused by the etching gas can be avoided.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and more particularly to an ashing and photoresist removal method for aluminum etching. Background Art

[0002] In semiconductor manufacturing processes, aluminum (Al) is commonly used in metal interconnect layers. Aluminum etching typically uses a dry etching process, where a photoresist is formed on the aluminum layer and then the aluminum layer is etched using the photoresist layer as a mask. Among them, the etching gas used for aluminum etching mainly includes chlorine gas (Cl2). After etching is completed, the residual chlorine gas on the wafer surface is prone to react with aluminum, resulting in aluminum corrosion defects, especially at the upper edge position of the wafer surface, which affects the performance of semiconductor devices. Summary of the Invention

[0003] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description section. The Summary of the Invention section of the present invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the protection scope of the claimed technical solution.

[0004] In view of the existing problems, an embodiment of the present invention provides an ashing and photoresist removal method for aluminum etching, the method comprising:

[0005] Step 1: Place the wafer after aluminum etching in the process chamber of an ashing device, the wafer comprising a semiconductor substrate, an aluminum layer, and a photoresist layer stacked in sequence, the photoresist layer being used as a mask during the etching of the aluminum layer;

[0006] Step 2: Introduce an ashing gas into the process chamber to make the pressure in the process chamber reach a preset pressure;

[0007] Step 3: Stop introducing the ashing gas into the process chamber to reduce the pressure in the process chamber;

[0008] Wherein, Step 2 and Step 3 are cyclically executed to form a pressure pulse, thereby removing the residual etching gas on the wafer surface.

[0009] In one embodiment, in Step 2, the pressure in the process chamber is gradually increased, and after the pressure in the process chamber reaches the preset pressure and lasts for a preset time, it is switched to Step 3.

[0010] In one embodiment, the preset time is 10s - 60s.

[0011] In one embodiment, the duration of Step 3 is 1s - 10s.

[0012] In one embodiment, step two includes a first stage and a second stage that are executed sequentially;

[0013] In the first stage, a first ashing gas is introduced into the process chamber to bring the pressure in the process chamber to a first preset pressure;

[0014] In the second stage, a second ashing gas is introduced into the process chamber to bring the pressure in the process chamber to a second preset pressure, which is higher than the first preset pressure.

[0015] In one embodiment, the first ashing gas includes at least water vapor, and the second ashing gas includes oxygen and / or nitrogen.

[0016] In one embodiment, the first preset pressure is 200 mT - 700 mT.

[0017] In one embodiment, the second preset pressure is 2000 mT - 5000 mT.

[0018] According to the ashing and deglueing method for aluminum etching provided by the present invention, the gas supply step and the gas supply stop step are cyclically executed to form a pressure pulse, and the residual etching gas on the wafer surface is removed through the pressure pulse, which can avoid aluminum corrosion caused by the etching gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The following drawings of the present invention are hereby incorporated as part of the present invention for understanding the present invention. The embodiments of the present invention are shown in the drawings and their descriptions are used to explain the principles of the present invention.

[0020] In the drawings:

[0021] Figures 1A to 1C A schematic diagram showing aluminum corrosion caused by residual chlorine is shown;

[0022] Figure 2 A schematic flow chart of an ashing and deglueing method for aluminum etching according to a specific embodiment of the present invention is shown;

[0023] Figure 3A and Figure 3B A schematic diagram showing the effect of the ashing and deglueing method for aluminum etching according to an embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] In the following description, numerous specific details are given in order to provide a more thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that the present invention may be practiced without one or more of these details. In other instances, well-known technical features have not been described in order to avoid obscuring the present invention.

[0025] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the dimensions and relative dimensions of layers and regions may be exaggerated for clarity. Like reference numerals throughout the figures denote like elements.

[0026] It should be understood that when an element or layer is referred to as being "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

[0027] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. are used herein for convenience in describing the relationship of one element or feature to another element or feature shown in the figures. It should be understood that, in addition to the orientation shown in the figures, spatial relationship terms are intended to also encompass different orientations of the device in use and operation. For example, if the device in the figures is flipped, then an element or feature described as "under" or "beneath" or "below" another element or feature will be oriented "on" the other element or feature. Thus, the exemplary terms "under" and "beneath" can include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein are to be interpreted accordingly.

[0028] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, identify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the related listed items.

[0029] The etching gas used for aluminum etching mainly includes chlorine gas (Cl2). Chlorine gas is extremely easy to react with water vapor (H2O) in the air to form hydrogen chloride (HCl). HCl continues to react with Al to generate aluminum chloride (AlCl3). AlCl3 reacts with H2O to generate HCl, and such cyclic reactions occur. The chemical reaction equations involved are as follows:

[0030] a) 6HCl + 2Al → 2AlCl3 + 3H2

[0031] b) 2AlCl3 + 3H2O → 6HCl + Al2O3.

[0032] After the aluminum etching is completed, the residual chlorine on the aluminum surface continues to undergo the above chemical reactions with aluminum, making it easy to generate aluminum corrosion defects on the wafer surface, especially at the upper edge position of the wafer, as Figures 1A to 1C shown.

[0033] In view of the existence of the foregoing technical problems, an embodiment of the present invention proposes an ashing and deglueing method for aluminum etching. Next, with reference to Figure 2 a detailed description is given of the ashing and deglueing method for aluminum etching according to an embodiment of the present invention. Figure 2 shows a schematic flow chart of the ashing and deglueing method for aluminum etching according to a specific embodiment of the present invention.

[0034] As Figure 2 shown, first, step one is executed. The wafer after aluminum etching is placed in the process chamber of the ashing equipment. The wafer includes a semiconductor substrate, an aluminum layer, and a photoresist layer stacked in sequence. The photoresist layer is used as a mask during the process of etching the aluminum layer.

[0035] Among them, the materials of the semiconductor substrate include but are not limited to at least one of the following materials: silicon (Si), germanium (Ge), silicon germanium (SiGe), silicon carbide (SiC), silicon germanium carbide (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP), or other III / V compound semiconductors, or silicon on insulator (SOI), silicon-on-insulator stacked silicon (SSOI), silicon germanium-on-insulator stacked silicon (S-SiGeOI), silicon germanium-on-insulator (SiGeOI), and germanium-on-insulator (GeOI). One or more active devices or passive devices can be formed in the semiconductor substrate. An interlayer dielectric layer is formed on the semiconductor substrate, and an aluminum layer is formed on the interlayer dielectric layer and is electrically connected to the metal interconnect structure formed in the interlayer dielectric layer. Among them, the aluminum layer can be a pure aluminum (Al) layer or an aluminum alloy (such as Al-Si, Al-Cu, etc.) layer.

[0036] A photoresist layer is formed on the aluminum layer and is used as a mask layer during the etching process of the aluminum layer. The photoresist layer can be directly formed on the surface of the aluminum layer, or other film layers can also be formed between the photoresist layer and the aluminum layer.

[0037] Exemplarily, during the etching process of the aluminum layer, first, a photoresist layer is spin-coated on the aluminum layer, and the photoresist layer is exposed through a mask; then, the exposed area or the non-exposed area is removed by an alkaline solution to form a patterned photoresist layer; finally, the aluminum layer is dry-etched using the patterned photoresist layer as a mask.

[0038] Among them, the dry etching process includes but is not limited to the reactive ion etching (RIE) process. The etching gas mainly includes chlorine gas, and in addition, it can also include boron trichloride (BCl3), argon (Ar), etc. During the dry etching process of the aluminum layer, a physical and chemical reaction occurs between chlorine and aluminum. Specifically, under the excitation of a radio frequency electric field, chlorine gas decomposes into highly reactive chlorine radicals and chloride ions. The chlorine radicals react with the aluminum surface to form aluminum chloride (AlCl3), which can be vaporized and removed at the process temperature; at the same time, the plasma generated by the radio frequency electric field is accelerated by the bias voltage to bombard the aluminum surface, destroying the oxide layer on the aluminum surface and promoting the desorption of by-products. The combination of the two realizes highly anisotropic etching.

[0039] After the etching is completed, the photoresist layer needs to be removed through an ashing process. In the ashing process, plasma is generated based on the ashing gas to decompose the hydrocarbons in the photoresist, oxidize or reduce them to gaseous products, and they can be discharged from the process chamber through a vacuum pump.

[0040] Specifically, place the wafer that has completed the aluminum etching process in the process chamber of the ashing equipment. Among them, the wafer that has completed the aluminum etching process can be transferred from the etching equipment to the ashing equipment for photoresist ashing, or the ashing function can be achieved by adjusting process parameters using the etching equipment.

[0041] In a conventional ashing process, the pressure in the process chamber of the ashing equipment always remains at 200mT - 700mT, and it is difficult to effectively remove the residual chlorine gas and other by-products in the etching step. To address this problem, the embodiments of the present invention cyclically and alternately execute Step 2 and Step 3 described below to form a pressure pulse, thereby removing the residual etching gas on the wafer surface.

[0042] Specifically, in Step 2, introduce an ashing gas into the process chamber to make the pressure in the process chamber reach a preset pressure. In Step 3, stop introducing the ashing gas into the process chamber to significantly reduce the pressure in the process chamber. Step 2 and Step 3 are cyclically executed to form a pressure pulse, and the residual chlorine gas and polymer by-products are completely removed from the wafer surface through the pulse impact and vibration effects, avoiding aluminum corrosion. Among them, Step 3 is used to briefly interrupt the air flow to form a pressure difference, and its duration is relatively short. In one example, Step 3 lasts for 1s - 10s.

[0043] Exemplarily, in Step 2, the pressure gradually increases as the reaction gas is introduced. When it reaches the preset pressure and lasts for a preset time, switch from Step 2 to Step 3. Exemplarily, when the pressure reaches the highest point, it lasts for 10s - 60s, briefly interrupt the air flow for 1s - 10s to form an instant low-pressure interval, and then inject high-pressure air flow again. In this way, the high and low pressures are cyclically switched to form a pressure pulse.

[0044] Furthermore, Step 2 may include a first stage and a second stage executed in sequence. In the first stage, introduce a first ashing gas into the process chamber to make the pressure in the process chamber reach a first preset pressure; in the second stage, introduce a second ashing gas into the process chamber to make the pressure in the process chamber reach a second preset pressure, and the second preset pressure is higher than the first preset pressure.

[0045] Among them, the first stage is used to soften the chlorine gas; the second stage is used to remove the softened chlorine gas and other polymer by-products. Exemplarily, the first ashing gas used in the first stage includes at least water vapor, and the second ashing gas includes oxygen and / or nitrogen.

[0046] Exemplarily, the first preset pressure is 200 mT - 700 mT, and the second preset pressure is 2000 mT - 5000 mT. Step three is set after the second stage of step two, so that the pressure in the reaction chamber rapidly decreases from the high pressure of 2000 mT - 5000 mT, thereby forming an instantaneous low-pressure interval. Then, step two is executed again to increase the pressure in the reaction chamber, so as to form a large pressure difference, and the chlorine gas on the wafer surface is removed through the vibration effect.

[0047] As Figure 3A and Figure 3B shown, based on the pulsed ashing and de-glueing process of the embodiments of the present invention, it can effectively avoid the generation of aluminum corrosion defects on the wafer surface. After aluminum etching, the aluminum corrosion on the wafer surface is significantly improved, and the aluminum etching window is significantly increased, improving the product yield and reliability.

[0048] So far, the process steps of the ashing and de-glueing method for aluminum etching according to the embodiments of the present invention have been completed. It can be understood that the ashing and de-glueing method for aluminum etching in this embodiment not only includes the above steps, but may also include other necessary steps before, during, or after the above steps, and they are all included in the scope of the ashing and de-glueing method in this embodiment.

[0049] According to the ashing and de-glueing method for aluminum etching provided by the embodiments of the present invention, the gas supply step and the gas supply stop step are cyclically executed to form a pressure pulse, and the residual etching gas on the wafer surface is removed through the pressure pulse, which can avoid aluminum corrosion caused by the etching gas.

[0050] The embodiments of the present invention also provide a semiconductor device. In the manufacturing process of this semiconductor device, the method in the foregoing embodiments is used for ashing and de-glueing after aluminum etching to avoid aluminum corrosion caused by the residual chlorine gas in aluminum etching.

[0051] The embodiments of the present invention also provide an electronic device, including the foregoing semiconductor device. The electronic device in this embodiment can be any electronic product or device such as a mobile phone, a tablet computer, a notebook computer, a netbook, a game console, a television, a VCD, a DVD, a navigator, a digital photo frame, a camera, a video camera, a recording pen, an MP3, an MP4, a PSP, etc., or can also be any intermediate product including a circuit. The electronic device in the embodiments of the present invention has better performance due to the use of the above semiconductor device.

[0052] The present invention has been described by the above embodiments. However, it should be understood that the above embodiments are only for the purpose of illustration and example, and are not intended to limit the present invention to the scope of the described embodiments. In addition, those skilled in the art can understand that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of protection required by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalent scope.

Claims

1. An ashing and degumming method for aluminum etching, characterized in that, The method includes: Step 1: Place the wafer after aluminum etching in the process chamber of an ashing device. The wafer includes a semiconductor substrate, an aluminum layer, and a photoresist layer stacked in sequence. The photoresist layer is used as a mask during the etching of the aluminum layer. Step 2: Introduce an ashing gas into the process chamber to make the pressure in the process chamber reach a preset pressure. Step 3: Stop introducing the ashing gas into the process chamber to reduce the pressure in the process chamber. Wherein, Step 2 and Step 3 are executed cyclically to form a pressure pulse, thereby removing the residual etching gas on the surface of the wafer.

2. The ashing and stripping method according to claim 1, characterized in that In Step 2, gradually increase the pressure in the process chamber. After the pressure in the process chamber reaches the preset pressure and lasts for a preset time, switch to Step 3.

3. The ashing and degluing method according to claim 2, characterized in that The preset time is 10s - 60s.

4. The ashing and degumming method according to claim 1, characterized in that The duration of Step 3 is 1s - 10s.

5. The ashing and degluing method according to claim 1, characterized in that, Step 2 includes a first stage and a second stage executed in sequence. In the first stage, introduce a first ashing gas into the process chamber to make the pressure in the process chamber reach a first preset pressure. In the second stage, introduce a second ashing gas into the process chamber to make the pressure in the process chamber reach a second preset pressure, and the second preset pressure is higher than the first preset pressure.

6. The ashing and degumming method according to claim 5, wherein The first ashing gas includes at least water vapor, and the second ashing gas includes oxygen and / or nitrogen.

7. The ashing and degluing method according to claim 5, characterized in that, The first preset pressure is 200mT - 700mT.

8. The ashing and degumming method according to claim 5, wherein The second preset pressure is 2000mT - 5000mT.

Images