A pre-evacuation chamber with wafer cleaning function and wafer cleaning method

Abstract

The application discloses a pre-evacuation chamber with wafer cleaning function and a wafer cleaning method, and belongs to the technical field of semiconductors, and solves the problems of low yield and process conversion alignment error caused by the existence of particulate matter on the back surface of a wafer in the prior art. The pre-evacuation chamber comprises a chamber, a nozzle, a support and a vacuum chuck. The support is arranged at the center of the chamber, the vacuum chuck is fixed at the top end of the support, and the nozzle is arranged in the radial direction of a circle with the vacuum chuck as the center. The vacuum chuck is used for fixing and rotating the wafer, and the nozzle is arranged below the wafer. The application is suitable for cleaning the back surface of the wafer.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor technology, and specifically relates to a pre-vacuum chamber with wafer cleaning function and a wafer cleaning method. Background Technology

[0002] Wafer cleaning is generally divided into two main categories: front-side cleaning and back-side cleaning. If there are particulate matter on the back side of the wafer, the tiny foreign matter can cause back-side helium leakage errors in the etching process chamber during processing. Small particles on the back side of the wafer can cause equipment errors and plasma deformation in the eight major semiconductor manufacturing processes, leading to various problems such as process drift (CD, low yield, particle) and alignment errors.

[0003] Existing wafer backside cleaning processes utilize water in wet cleaning equipment to clean the backside of the wafer, thereby removing the particles on the back. Integrated circuit manufacturing processes involve multiple wet cleaning steps, requiring cleaning before each etching process, significantly increasing integrated circuit manufacturing time. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a pre-vacuum chamber with wafer cleaning function and a wafer cleaning method to solve the problems of low yield and wafer transfer alignment errors caused by particulate matter on the back side of the wafer in the prior art.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] A pre-vacuum chamber with wafer cleaning function includes a chamber, a nozzle, a support, and a vacuum chuck.

[0007] The support is located at the center of the chamber, the vacuum chuck is fixed at the top of the support, and the nozzle is located in the radial direction of a circle with the vacuum chuck as the center; the vacuum chuck is used to fix the wafer and drive the wafer to rotate, and the nozzle is located below the wafer.

[0008] In one possible design, a filter is installed on the air intake line of the nozzle.

[0009] In one possible design, an N2 inlet and an exhaust port are located at the bottom of the chamber, and a diffuser is installed on the N2 inlet.

[0010] In one possible design, the nozzle is provided with micropores that can uniformly blow gas toward the back of the wafer.

[0011] In one possible design, the number of micropores is 1 to 10,000, and the micropore size is 0.001 mm to 50 mm.

[0012] In one possible design, the nozzle is one of the following tube shapes: round, triangular, square, pentagonal, or hexagonal.

[0013] In one possible design, a nozzle support is provided below the nozzle.

[0014] A wafer cleaning method includes the following steps:

[0015] The wafer is transferred to the pre-vacuum chamber and fixed in place using a vacuum chuck.

[0016] In atmospheric conditions, the vacuum chuck rotates the wafer, and as the evacuation begins, the nozzle blows gas to clean the back side of the wafer.

[0017] After the pressure in the pre-evacuation chamber is evacuated to 300mT, the blowing of gas is stopped, and the falling fine foreign matter is discharged from the pumping line.

[0018] In one possible design, the wafer rotation speed is 10 to 1000 rpm.

[0019] In one possible design, the flow rate of the gas blown by the nozzle is 1 to 50 Torr.

[0020] Compared with the prior art, the present invention can achieve at least one of the following technical effects:

[0021] 1) In the pre-vacuum chamber of this invention, the wafer is fixed with a vacuum chuck. While rotating, gas (e.g., N2) is blown onto the wafer surface to remove foreign matter, solving problems such as errors caused by fine particles or process drift due to plasma deformation (CD, low yield, particle). It also improves back-side leakage of equipment caused by fine particles on the back side (reducing downtime losses and improving productivity).

[0022] 2) The present invention sets up a back-side cleaning device in the pre-vacuum chamber, so that the back-side cleaning of the wafer in the pre-etching process (wet etching) can be skipped, avoiding the need for wafer cleaning before each etching process in the integrated circuit manufacturing process, which greatly saves the manufacturing time and processes of integrated circuits.

[0023] 3) The nozzles provided below the wafer in this invention have a microporous structure, through which gas can be uniformly blown onto the back side of the wafer to effectively remove foreign matter.

[0024] 4) The nozzle of the present invention is equipped with a filter in the air inlet pipe, which can prevent the introduction of foreign substances.

[0025] Other features and advantages of the invention will be set forth in the following description, and in part will be obvious from the description or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings. Attached Figure Description

[0026] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0027] Figure 1 This is a schematic diagram of a pre-vacuum chamber structure;

[0028] Figure 2 This is a schematic diagram of the pre-vacuum chamber structure in Example 1;

[0029] Figure 3 This is a schematic diagram showing the distribution of micropores on a nozzle;

[0030] Figure 4 This is a schematic diagram showing the distribution of micropores on another type of nozzle;

[0031] Figure 5 This is a schematic diagram showing the distribution of micropores on another type of nozzle;

[0032] Figure 6 This is a schematic diagram showing the distribution of micropores on another type of nozzle.

[0033] Figure label:

[0034] 1-Wafer; 2-Hanging ring; 3-N2 inlet; 4-Ejection port; 5-Diffuser; 6-Vacuum chuck; 7-Nozzle; 8-Filter; 9-Micropore; 10-Foreign material; 11-Support; 12-Cavity. Detailed Implementation

[0035] Embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0036] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0037] In the context of this disclosure, when a layer / element is referred to as being "above" another layer / element, the layer / element may be directly above the other layer / element, or there may be an intermediate layer / element between them. Additionally, if a layer / element is "above" another layer / element in one orientation, then when the orientation is reversed, the layer / element may be "below" the other layer / element.

[0038] In the wafer processing steps, the transfer of wafers from one processing chamber to another requires the coordinated operation of an Atmosphere Transfer Module (ATM), a loadlock, and a Vacuum Transfer Module (VTM). The loadlock connects to the Atmosphere Transfer Module at one end and the Vacuum Transfer Module at the other. During wafer manufacturing, processing chambers are mostly used to process wafers under vacuum or near-vacuum conditions. The loadlock serves as a buffer to adjust the pressure on the wafer being processed. After the wafer is transferred from the Atmosphere Transfer Module to the loadlock, the loadlock adjusts the atmospheric pressure experienced by the wafer to within the pressure range maintained by the loadlock. Then, the loadlock transfers the wafer to the loadlock, which in turn transfers it to the processing chamber for further processing. After processing is complete, the reverse process described above is used to transfer the wafer from the processing chamber to the atmospheric transport module, ready for the next processing step.

[0039] Figure 1 This is a schematic diagram of a pre-vacuum chamber structure, including a chamber, an N2 inlet 3, an evacuation port 4, and a lifting ring 2. A diffuser 5 is installed at the N2 inlet 3. The lifting ring 2 is used to place the wafer 1, and the evacuation port 4 is used to adjust the pressure inside the pre-vacuum chamber. After the wafer 1 is transferred into the pre-vacuum chamber in atmospheric transport mode, it is evacuated, and then the wafer 1 is transported to the vacuum transport module.

[0040] In the above-mentioned pre-vacuum chamber structure, the N2 inlet 3 is located at the bottom of the chamber and is a certain distance away from the back side of the wafer. After entering the pre-vacuum chamber through the N2 inlet, the nitrogen diffuses in the pre-vacuum chamber. Due to the influence of the number and location of the N2 inlets, the cleaning effect of N2 on the back side of the wafer is uneven during the process, and foreign matter is not completely removed. At the same time, the fine foreign matter that falls off during the cleaning process cannot be discharged from the exhaust line in time and will mix into the sprayed nitrogen, causing pollution of the cleaning nitrogen.

[0041] To better address the technical problem of low yield caused by particulate matter on the back side of wafers, and to further improve the cleaning effect and more thoroughly remove foreign matter, this invention discloses a pre-vacuum chamber with wafer cleaning function, such as... Figure 2 As shown, it includes a chamber, a support, a vacuum chuck 6 fixed on the support, and a nozzle 7. The vacuum chuck 6 is used to fix the wafer 1 and drive the wafer 1 to rotate; the nozzle 7 is located below the wafer 1 and is used to clean the back of the wafer 1.

[0042] The vacuum chuck of the present invention is mounted on a support located at the center of the chamber, and the wafer 1 is supported and fixed by the vacuum chuck 6. Compared with the lifting ring described above, the vacuum chuck has better adaptability and can be used for fixing and processing wafers of various sizes.

[0043] When wafer processing is required, a robotic arm places the wafer above a vacuum chuck. Considering that if the wafer is placed off-center on the vacuum chuck, it will cause unevenness and inconsistency in the cleaning process, thus affecting the cleaning effect, this invention sets a pressure sensor on the top of the vacuum chuck, and the pressure sensors are arranged in pairs symmetrically along the diameter of the vacuum chuck.

[0044] When the robotic arm places the wafer on the vacuum suction cup, if all the pressure sensors detect the same pressure, it indicates that the wafer is not biased; if one or more pressure sensors detect different pressures, it indicates that the wafer is biased and its position needs to be adjusted.

[0045] Considering that the wafer may be biased in any direction on the vacuum chuck, the pressure sensor of this invention is at least one pair, and can be two, four, eight, etc., with multiple pairs of pressure sensors evenly arranged along the circumference of the vacuum chuck. Multiple pairs of pressure sensors can be set on the vacuum chuck to ensure that even slight bias of the wafer in any direction can be detected, thereby allowing for timely adjustment of the wafer's position. The number of pressure sensors can also be flexibly adjusted as needed.

[0046] Since the pressure sensor is located on the top of the vacuum chuck, to prevent it from protruding from the upper surface of the chuck and scratching the wafer surface, the pressure sensor is embedded in the vacuum chuck, with its top flush with the upper surface of the chuck. It is understood that the pressure sensor can also be located on the bottom surface of the vacuum chuck, i.e., the back surface.

[0047] Preferably, an image monitor can also be set in the vacuum chamber to monitor the wafer placement in real time and adjust the wafer position as needed. This also helps to prevent the center of wafer 1 from not being accurately aligned with the vacuum chuck 6 during the transfer process, which would cause uneven cleaning of wafer 1; and to prevent wafer 1 from becoming skewed after cleaning the back of wafer 1, which would cause the robotic arm to grab it incorrectly during the next transport.

[0048] In the pre-vacuum chamber of this invention, wafer 1 is fixed by a vacuum chuck 6. While rotating, gas, such as N2, is blown onto the back of wafer 1 through nozzle 7 to remove foreign matter 10. This solves problems caused by errors due to fine particles or process drift due to plasma deformation (CD, low yield, particle size), and improves back-side He leakage caused by fine particles on the back (reducing downtime and improving productivity). The back-side cleaning of wafer 1 before etching (wet cleaning) can be skipped.

[0049] In one possible embodiment, the vacuum suction cup 6 is located at the center of the chamber, and the nozzle 7 is located in the radial direction of a circle centered on the vacuum suction cup 6.

[0050] To ensure uniform pressure and flow rate of the cleaning gas ejected from the nozzle and guarantee cleaning effectiveness, the plane of the nozzle is lower than the bottom surface of the vacuum chuck. This means that after the wafer is placed on the top surface of the vacuum chuck, the nozzle is directly below the back surface of the wafer. The distance between the nozzle and the back surface of the wafer can be 1–10 cm, for example, 1 cm, 2 cm, 5 cm, or 8 cm. This allows the gas ejected from the nozzle 7 to clean the entire back surface of the wafer 1 when the vacuum chuck 6 rotates the wafer 1.

[0051] Nozzle 7 can be fixed to the side wall of the pre-vacuum chamber by a mechanical structure, or it can be fixed to the bottom surface of the pre-vacuum chamber by a mechanical structure, such as... Figure 2 As shown, nozzle 7 is fixed to the bottom surface of the pre-vacuum chamber through a pipeline, and filter 8 is installed on the air inlet pipeline. Clean gas passes through the filter through the pipeline and is then ejected from nozzle 7.

[0052] The nozzle 7 can be a tube in the shape of a circle, triangle, square, pentagon, or hexagon. The nozzle 7 is provided with micropores that can uniformly blow gas onto the back side of the wafer 1. The number of micropores 9 can be 1 to 10,000, such as 500, 1,000, 2,000, or 5,000, etc., and the size of the micropores 9 is 0.001 mm to 50 mm, such as 0.1 mm, 1 mm, or 10 mm, etc. The number and size of the micropores can be determined according to the wafer area. For example, ... Figures 3-6 As shown, the micro-orifices 9 can be configured as 6 in one row, 12 in two rows, 24 in three rows, or 32 in four rows. The jet width formed by multiple rows of micro-orifices 9 (i.e., Figures 3-6 The length of the rectangle is greater than or equal to the radius of the wafer, and the number of rows of microvias that are open can be adjusted according to the size of the wafer.

[0053] Nozzle 7 is made of materials such as stainless steel, ceramic, or nickel, which are used in diffusers in semiconductor devices.

[0054] A filter 8 is installed on the air inlet pipe of nozzle 7 to filter impurities in the gas and prevent the introduction of new foreign substances due to the blowing of gas.

[0055] The pre-vacuum chamber of this invention is provided with an N2 inlet 3 and an air extraction port 4, wherein the air extraction port and the nozzle are located on the same side and the air extraction port is located below the nozzle. In this way, the fine foreign matter that falls off during the cleaning process can be discharged from the air extraction line in time, avoiding the fine foreign matter that falls off during the cleaning process from mixing into the cleaning gas again and causing pollution to the cleaning gas.

[0056] In order to improve the uniform distribution of nitrogen gas entering from N2 inlet 3 in the pre-vacuum chamber, the present invention provides a diffuser 5 at N2 inlet 3 and an exhaust port 4 for adjusting the pressure in the pre-vacuum chamber.

[0057] The present invention also provides a wafer cleaning method, comprising the following steps:

[0058] Transfer wafer 1 to the pre-vacuum chamber and fix wafer 1 in place using a vacuum chuck.

[0059] In atmospheric conditions, the vacuum chuck rotates the wafer 1, and as the evacuation begins, the nozzle 7 blows gas to clean the back side of the wafer 1.

[0060] After the pressure in the pre-evacuation chamber is evacuated to 300mT, the blowing of gas is stopped, and the falling fine foreign matter is discharged from the pumping line.

[0061] Preferably, the rotational speed of wafer 1 is 10 to 1000 rpm, such as 20 rpm, 100 rpm, 200 rpm, 300 rpm, 400 rpm, 600 rpm, 800 rpm, etc., and the flow rate of gas blown by nozzle 7 is 1 to 50 Torr, such as 18 Torr, 20 Torr, 30 Torr, 40 Torr, 45 Torr, etc.

[0062] Compared to existing technologies, in the pre-vacuum chamber of this invention, the wafer is fixed by a vacuum chuck and, while rotating, a gas (e.g., N2) is blown onto the wafer surface to remove foreign matter, solving problems such as errors caused by fine particles or process drift due to plasma deformation (CD, low yield, particle). It also improves back-side leakage caused by fine particles on the back side of the equipment (reducing downtime losses and improving productivity).

[0063] This invention incorporates a back-side cleaning device within a pre-vacuum chamber, allowing the back-side cleaning of the wafer to be skipped before the etching process (wet etching). This avoids the need for wafer cleaning before each etching process in integrated circuit manufacturing, significantly saving manufacturing time and steps.

[0064] The nozzle positioned beneath the wafer in this invention has a microporous structure, allowing gas to be uniformly blown onto the back side of the wafer through the micropores, effectively removing foreign matter. A filter is installed in the air inlet pipe of the nozzle to prevent the introduction of foreign matter.

[0065] Example 1

[0066] A pre-vacuum chamber with wafer cleaning function, such as Figure 2 As shown, it includes a chamber 12, a support 11, a vacuum chuck 6 fixed on the support 11, and a nozzle 7. The nozzle 7 is located below the wafer 1 and is used to clean the back side of the wafer 1.

[0067] The vacuum chuck 6 is positioned at the center of the chamber 12, and the nozzle 7 is positioned along the radius of a circle centered on the vacuum chuck 6. The nozzle 7 is a square tube, and its upper surface (the side closest to the wafer) has micro-holes 9 that can uniformly blow gas onto the back side of the wafer 1. The micro-holes 9 are 2mm in size and are arranged in 4 rows of 32 holes. The nozzle 7 is made of stainless steel.

[0068] A filter 8 is installed on the air inlet pipe of nozzle 7 to filter impurities in the gas and prevent the introduction of new foreign substances due to the blowing of gas.

[0069] Example 2

[0070] A wafer cleaning method, employing the pre-vacuum chamber with wafer cleaning function as described in Example 1, includes the following steps:

[0071] Transfer wafer 1 to the pre-vacuum chamber and fix wafer 1 in place using a vacuum chuck.

[0072] Under atmospheric conditions, the vacuum chuck rotates wafer 1. At the same time as the evacuation begins, nozzle 7 blows N2 to clean the back side of wafer 1. The rotation speed of wafer 1 is 300 rpm, and the flow rate of N2 blown by nozzle 7 is 20 Torr.

[0073] After the pressure in the pre-evacuation chamber is evacuated to 300mT, the blowing of gas is stopped, and the falling fine foreign matter is discharged from the pumping line.

[0074] The above description does not provide detailed explanations of the technical aspects of each layer's patterning, etching, etc. However, those skilled in the art should understand that various technical means can be used to form layers and regions of the desired shape. Furthermore, to form the same structure, those skilled in the art can also design methods that are not entirely identical to those described above. Additionally, although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A wafer cleaning method, characterized in that, The following pre-vacuum chamber with wafer cleaning function is used. The pre-vacuum chamber includes a chamber, a nozzle, a support, and a vacuum chuck. The support is located at the center of the chamber, the vacuum chuck is fixed to the top of the support, and the nozzle is located in the radial direction of a circle with the vacuum chuck as the center; the vacuum chuck is used to fix the wafer and drive the wafer to rotate, and the nozzle is located below the wafer; The bottom of the chamber is provided with an air extraction port, which is located on the same side as the nozzle and below the nozzle. The nozzle is equipped with micro-holes that can uniformly blow gas onto the back side of the wafer. The jet width formed by multiple rows of micro-holes is greater than or equal to the radius of the wafer, and the number of rows of micro-holes that are open can be adjusted according to the size of the wafer. The distance between the nozzle and the back of the wafer is 1. 10cm; The wafer cleaning method includes the following steps: The wafer is transferred to the pre-vacuum chamber and fixed in place using a vacuum chuck. In atmospheric conditions, the vacuum chuck rotates the wafer, and as the evacuation begins, the nozzle blows gas to clean the back side of the wafer. After the pressure in the pre-evacuation chamber is evacuated to 300mT, the blowing of gas is stopped, and the falling fine foreign matter is discharged from the pumping line.

2. The wafer cleaning method according to claim 1, characterized in that, A filter is installed on the air inlet pipe of the nozzle.

3. The wafer cleaning method according to claim 1, characterized in that, The bottom of the chamber is provided with an N2 inlet, and a diffuser is provided on the N2 inlet.

4. The wafer cleaning method according to claim 1, characterized in that, The nozzle is equipped with micropores that can uniformly blow gas onto the back side of the wafer.

5. The wafer cleaning method according to claim 1, characterized in that, The number of micropores is 1 to 10,000, and the size of the micropores is 0.001 mm to 50 mm.

6. The wafer cleaning method according to claim 1, characterized in that, The nozzle is one of the following tube shapes: circular, triangular, square, pentagonal, or hexagonal.

7. The wafer cleaning method according to any one of claims 1-6, characterized in that, A nozzle support is provided below the nozzle.

8. The wafer cleaning method according to claim 1, characterized in that, The wafer rotation speed is 10~1000 rpm.

9. The wafer cleaning method according to claim 1, characterized in that, The flow rate of the gas blown by the nozzle is 1~50 Torr.

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