Inclined plane etching method

Abstract

The invention relates to the technical field of semiconductors, in particular to a slope etching method. The inclined plane etching method comprises the following steps: placing a wafer on a turntable of a back cleaning machine table in a manner that the back surface of the wafer faces upwards; controlling the turntable to rotate, and introducing N2 to the lower part of the wafer; wherein the rotating speed of the rotating disc is lower than that of the rotating disc in the back cleaning process condition, and the flow of N2 is lower than that of N2 in the back cleaning process condition; chemical liquid medicine is sprayed towards the back face of the wafer; wherein the spraying duration of the chemical liquid medicine is longer than the washing duration of the chemical liquid medicine in the back cleaning process condition. According to the inclined plane etching method provided by the invention, a special inclined plane etching machine does not need to be additionally introduced, the cost can be saved, the production space cannot be additionally occupied, the interval duration of a back surface cleaning process and a front surface etching process can be shortened, and the efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a bevel etching method. Background Art

[0002] In the semiconductor manufacturing process, bevel etching of the wafer edge is one of the important process steps. Its core purpose is to solve the multiple problems caused by edge defects by directionally removing specific materials at the wafer edge, thereby improving chip yield and reliability.

[0003] The traditional bevel etching process requires a dedicated bevel etching machine to complete. However, the equipment of the dedicated bevel etching machine is expensive and will take up a certain amount of additional production space, resulting in high costs and waste of production space. Summary of the Invention

[0004] The object of the present invention is to provide a bevel etching method to alleviate the technical problems of high cost and waste of production space in the bevel etching process in the related art.

[0005] The bevel etching method provided by the present invention comprises:

[0006] Place the wafer with the back side facing up on the turntable of the backside cleaning machine;

[0007] Controlling the rotation of the turntable to introduce N2 gas below the wafer; wherein the rotation speed of the turntable is lower than the rotation speed of the turntable in the backside cleaning process conditions, and the flow rate of the N2 gas is lower than the flow rate of the N2 gas in the backside cleaning process conditions;

[0008] A chemical liquid is sprayed toward the back side of the wafer; wherein the spraying time of the chemical liquid is longer than the rinsing time of the chemical liquid in the back side cleaning process conditions.

[0009] Preferably, as an implementable embodiment, the rotation speed of the turntable is 380-450 rpm.

[0010] Preferably, as an implementable embodiment, the rotation speed of the turntable is 390-430 rpm.

[0011] Preferably, as an implementable embodiment, the rotation speed of the turntable is 400 rpm.

[0012] Preferably, as an implementable embodiment, the flow rate of N2 is 40 to 70 L / min.

[0013] Preferably, as an implementable embodiment, the flow rate of N2 is 45 to 60 L / min.

[0014] Preferably, as an implementable embodiment, the flow rate of N2 is 50 L / min.

[0015] Preferably, as an implementable embodiment, the spraying time of the chemical liquid is 50 to 120 seconds.

[0016] Preferably, as an implementable method, the spraying time of the chemical liquid is 60 to 70 seconds.

[0017] Preferably, as an implementable embodiment, the bevel etching width of the wafer is 0.5 to 2.5 mm.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The bevel etching method provided by the present invention can be applied to a back-side cleaning machine. By simply adjusting the process conditions, the back-side cleaning machine can be used to achieve bevel etching of the front edge of the wafer while spraying chemical liquid on the back of the wafer. Specifically, the rotation speed of the turntable is set to be lower than the rotation speed of the turntable in the back cleaning process conditions to reduce the centrifugal force of the chemical liquid, so that the chemical liquid has the conditions to penetrate from the back side to the front side from the edge of the wafer; the flow rate of N2 introduced to the bottom of the wafer is set to be lower than the flow rate of N2 introduced to the bottom of the wafer in the back cleaning process conditions to reduce the resistance of the airflow to the chemical liquid, so that the chemical liquid can penetrate from the back side to the front side from the edge of the wafer, wherein N2 is continuously introduced during the process; on this basis, the chemical liquid is sprayed toward the back side of the wafer, and the spraying time of the chemical liquid is set to be longer than the chemical liquid rinsing time in the back cleaning process conditions, so that the chemical liquid sprayed on the back side of the wafer has enough time to penetrate from the edge of the wafer to the front side of the wafer, thereby ensuring the amount of chemical liquid that penetrates to the front side of the wafer, thereby ensuring the effect of the chemical liquid on bevel etching the front edge of the wafer.

[0020] Therefore, by adopting the bevel etching method provided by the present invention, the original back side cleaning machine can be used to achieve the effect of bevel etching on the front edge of the wafer, thereby, there is no need to introduce an additional dedicated bevel etching machine, which can save more than 40% of the cost and will not occupy additional production space; in addition, since a single machine (back side cleaning machine) can complete the back side cleaning and front side etching of the wafer, compared with the long-distance transfer of the wafer between the back side cleaning machine and the bevel etching machine to realize the back side cleaning and front side etching on the two machines respectively, the distance transfer time can be saved, and the interval time between the two processes (back side cleaning and front side etching) can be shortened by 30%, thereby improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 A schematic flow chart of a bevel etching method provided in an embodiment of the present invention;

[0023] Figure 2 This is a graph showing the thickness of the oxide film after etching in Example 1 of the present invention;

[0024] Figure 3 This is a test diagram of the oxide film thickness after etching in Example 2 of the present invention. DETAILED DESCRIPTION

[0025] In related technologies, single-wafer backside cleaning machines are primarily used for wafer backside cleaning. However, implementing bevel etching on the wafer edge requires the addition of a dedicated bevel etching machine, which not only increases costs but also takes up additional production space. To reduce equipment costs and save space, outsourcing the bevel etching process is often chosen. However, outsourcing testing is complex and expensive, and there's also the issue of being unable to meet customers' diverse tape-out testing needs.

[0026] Based on this, the present invention provides a bevel etching method. By adjusting the process parameters, the back side cleaning machine can achieve the front side etching effect. Thus, the existing back side cleaning machine can be used to perform the bevel etching process on the front edge of the wafer. There is no need to introduce a dedicated bevel etching machine, which will not increase the equipment cost and will not occupy additional production space. Of course, there will be no problems such as complicated procedures, high costs and inability to meet the diverse wafer testing needs of customers brought about by outsourcing the bevel etching process.

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0028] The present invention will be further described in detail below through specific implementation examples in conjunction with the accompanying drawings.

[0029] Figure 1 A schematic flow chart of a bevel etching method provided in one embodiment of the present invention, the method comprising:

[0030] S102, placing the wafer with its back side facing upward on a turntable of a back side cleaning machine;

[0031] S104, controlling the rotation of the turntable to introduce N2 gas to the bottom of the wafer; wherein the rotation speed of the turntable is lower than the rotation speed of the turntable in the backside cleaning process conditions, and the flow rate of N2 gas is lower than the flow rate of N2 gas in the backside cleaning process conditions;

[0032] S106 , spraying a chemical liquid toward the back side of the wafer; wherein the spraying time of the chemical liquid is longer than the rinsing time of the chemical liquid in the back side cleaning process conditions.

[0033] The bevel etching method provided in this embodiment can be applied to a backside cleaning machine. By simply adjusting the process conditions, the backside cleaning machine can be used to achieve bevel etching of the front edge of the wafer while spraying chemical liquid on the back side of the wafer. Specifically, the rotation speed of the turntable is set to be lower than the rotation speed of the turntable in the back cleaning process conditions to reduce the centrifugal force of the chemical liquid, so that the chemical liquid has the conditions to penetrate from the back side to the front side from the edge of the wafer; the flow rate of N2 introduced to the bottom of the wafer is set to be lower than the flow rate of N2 introduced to the bottom of the wafer in the back cleaning process conditions to reduce the resistance of the airflow to the chemical liquid, so that the chemical liquid can penetrate from the back side to the front side from the edge of the wafer, wherein N2 is continuously introduced during the process; on this basis, the chemical liquid is sprayed toward the back side of the wafer, and the spraying time of the chemical liquid is set to be longer than the chemical liquid rinsing time in the back cleaning process conditions, so that the chemical liquid sprayed on the back side of the wafer has enough time to penetrate from the edge of the wafer to the front side of the wafer, thereby ensuring the amount of chemical liquid that penetrates to the front side of the wafer, thereby ensuring the effect of the chemical liquid on bevel etching the front edge of the wafer.

[0034] Therefore, by adopting the bevel etching method provided in this embodiment, the original back side cleaning machine can be used to achieve the effect of bevel etching on the front edge of the wafer, thereby, there is no need to introduce an additional dedicated bevel etching machine, which can save more than 40% of the cost and will not occupy additional production space; in addition, since a single machine (back side cleaning machine) can complete the back side cleaning and front side etching of the wafer, compared with the long distance transfer of the wafer between the back side cleaning machine and the bevel etching machine to realize the back side cleaning and front side etching on the two machines respectively, the distance transfer time can be saved, and the interval time between the two processes (back side cleaning and front side etching) can be shortened by 30%, thereby improving efficiency.

[0035] In addition, compared with outsourcing the bevel etching process, the process is simpler, the cost is lower, and it can meet customers' diverse wafer testing needs.

[0036] Specifically, the rotation speed of the turntable can be set to 380-450 rpm. At this rotation speed, the chemical solution can smoothly penetrate from the edge of the wafer from the back side to the front side, thereby smoothly performing the bevel etching process on the wafer. It should be noted that the turntable speed of the back cleaning machine is generally set to 600 rpm when performing back cleaning on the wafer. In this embodiment, when using the back cleaning machine for bevel etching, the turntable speed is significantly reduced.

[0037] Preferably, the rotation speed of the turntable can be set to 390-430 rpm. At this rotation speed, the wafers carried by the turntable can obtain a better edge etching width range and etching uniformity.

[0038] Furthermore, the rotation speed of the turntable can be set to 400 rpm. At this rotation speed, the turntable is conducive to achieving the best balance between the edge etching width range and etching uniformity of the wafer it carries.

[0039] Specifically, the flow rate of N2 introduced under the wafer can be set to 40-70 L / min. Under this condition, the chemical solution can smoothly penetrate from the edge of the wafer from the back to the front, thereby enabling the wafer to be smoothly bevel-etched. It should be noted that when the back cleaning machine is performing back-side cleaning on the wafer, the flow rate of N2 introduced under the wafer is generally set at 200 L / min. In this embodiment, when using the back cleaning machine for bevel etching, the N2 flow rate under the wafer is significantly reduced.

[0040] Preferably, the N2 flow rate introduced to the bottom of the wafer can be set to 45-60 L / min. Under this condition, the wafer can obtain a better edge etching width range and etching uniformity.

[0041] Furthermore, the N2 flow rate under the wafer can be set to 50L / min. Under this condition, it is beneficial to achieve the best balance between the edge etching width range and etching uniformity of the wafer.

[0042] Specifically, the chemical liquid spraying time can be set to 50 to 120 seconds. Under this condition, the wafer can achieve a good etching width range. It should be noted that when the backside cleaning machine performs backside cleaning on the wafer, the chemical liquid rinsing time is generally set to 30 seconds. In this embodiment, when the backside cleaning machine is used for bevel etching, the chemical liquid spraying time is significantly extended.

[0043] Furthermore, the chemical liquid spraying time can be set to 60-70 seconds. Under this condition, the wafer can obtain a better edge etching width range and etching uniformity. Preferably, the chemical liquid spraying time is set to 60 seconds, which is conducive to achieving the best balance between the edge etching width range and etching uniformity of the wafer.

[0044] The wafer bevel etch width can be set within a range of 0.5 to 2.5 mm. Specifically, the wafer edge etch width can be adjusted by regulating process parameters.

[0045] By using the bevel etching method provided in this embodiment, the etching uniformity of the wafer can be controlled within 90%, and the process controllability is good.

[0046] In order to further illustrate the technical solution of the present invention, the bevel etching method provided by the present invention is described in more detail below in conjunction with specific embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0047] Example 1

[0048] Place the wafer with the back side facing up on the turntable of the backside cleaning machine;

[0049] The turntable is controlled to rotate and N2 is introduced under the wafer; the turntable speed is 410 rpm and the N2 flow rate is 60 L / min;

[0050] The chemical liquid is sprayed toward the back side of the wafer; wherein the spraying time of the chemical liquid is 90 seconds.

[0051] Figure 2 This is a test diagram of the thickness of an oxide (such as silicon oxide) film with a thickness of 1000A after bevel etching using the above process conditions, where the edge area Z is the bevel etching part. Figure 2 It can be seen that by adopting the parameter combination of Example 1, the backside clean machine can etch the front crystal edge when spraying chemical liquid on the back of the wafer, basically etching away 0.5-2.5 mm (etching width) of the front crystal edge, and the average etching thickness value (Avg) of the bevel etching part is 568.13A, and the bevel etching uniformity (1Sig) is 88.807%, which meets the bevel etching requirements.

[0052] Example 2

[0053] Place the wafer with the back side facing up on the turntable of the backside cleaning machine;

[0054] The turntable is controlled to rotate and N2 is introduced under the wafer; the turntable speed is 400 rpm and the N2 flow rate is 50 L / min;

[0055] A chemical liquid is sprayed toward the back side of the wafer; wherein the spraying time of the chemical liquid is 60 seconds.

[0056] Figure 3This is a schematic diagram of the thickness test of an oxide (such as silicon oxide) film with a thickness of 1000Å after bevel etching under the above process conditions, wherein the edge area Z is the bevel etching part. Figure 3 It is known that the parameter combination of Example 1 enables the backside clean machine to etch the front edge of the wafer when spraying chemical solution on the back side of the wafer. It can basically etch away 0.5-2mm (etching width) of the front edge. The average etching thickness value (Avg) of the bevel etched portion is 605.825Å, and the bevel etching uniformity (1Sig) is 81.886%. Although the etching range is smaller than that of Example 1, the stability is enhanced, and the oxide film layer can be etched more thoroughly and uniformly. Therefore, the parameter setting of this example is preferred.

[0057] An embodiment of the present invention also provides a back-side cleaning machine, which includes a turntable, an air intake assembly, a liquid spray assembly and a controller. The controller includes at least one processor and at least one memory. The memory stores a computer program. When the computer program is executed by the processor, the bevel etching method in any of the above embodiments is implemented.

[0058] The back surface cleaning machine provided in this embodiment can implement the above-mentioned bevel etching method, and therefore has all the advantages of the above-mentioned bevel etching method, which will not be described in detail here.

[0059] For example, the controller can be a host computer or a slave computer. The controller can control the turntable to rotate at a set speed. The controller can control the opening of a valve on an air inlet assembly to introduce a corresponding gas (such as N2) into the process chamber. The controller can also control the opening and closing of the valve on the air inlet assembly to control the gas flow rate. The controller can control the liquid spray assembly to spray a chemical solution into the process chamber to achieve chemical solution etching of the wafer.

[0060] Finally, it should be noted that in this document, terms such as "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0061] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to the embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A bevel etching method, characterized in that: include: Place the wafer with the back side facing up on the turntable of the backside cleaning machine; Controlling the rotation of the turntable to introduce N2 gas below the wafer; wherein the rotation speed of the turntable is lower than the rotation speed of the turntable in the backside cleaning process conditions, and the flow rate of the N2 gas is lower than the flow rate of the N2 gas in the backside cleaning process conditions; A chemical liquid is sprayed toward the back side of the wafer; wherein the spraying time of the chemical liquid is longer than the rinsing time of the chemical liquid in the back side cleaning process conditions.

2. The bevel etching method according to claim 1, wherein: The rotating speed of the turntable is 380-450 rpm.

3. The bevel etching method according to claim 2, wherein: The rotating speed of the turntable is 390-430 rpm.

4. The bevel etching method according to claim 3, wherein: The rotating speed of the turntable is 400 rpm.

5. The bevel etching method according to claim 1, wherein: The flow rate of N2 is 40-70 L / min.

6. The bevel etching method according to claim 5, wherein: The flow rate of N2 is 45-60 L / min.

7. The bevel etching method according to claim 6, wherein: The flow rate of N2 is 50 L / min.

8. The bevel etching method according to claim 1, wherein: The spraying time of the chemical liquid is 50 to 120 seconds.

9. The bevel etching method according to claim 8, wherein: The spraying time of the chemical liquid is 60 to 70 seconds.

10. The bevel etching method according to any one of claims 1 to 9, characterized in that: The bevel etching width of the wafer is 0.5 to 2.5 mm.

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