A system and method for controlling critical dimensions of wafer edge

Abstract

The present invention relates to a system and method for controlling the critical dimensions of a wafer edge, which belongs to the field of semiconductor manufacturing technology, and solves the problem that the critical dimensions of the wafer edge cannot be effectively controlled in the prior art, resulting in uneven critical dimensions of the wafer edge and inability to obtain the desired wafer contour. The system for controlling the critical dimensions of a wafer edge includes a top plate, an inner electrode, an outer electrode, an electrostatic chuck for placing a wafer, an edge ring for protecting the wafer edge, a first air intake system, and a second air intake system; the first air intake system includes a first air hole that passes through the top plate and the outer electrode, and the first air hole is used to supply air to the edge of the wafer; the second air intake system includes a second air hole that passes through the top plate and the inner electrode, and the second air hole is used to supply air to the center of the wafer. The present invention realizes precise control of the critical dimensions of the end edge of a specific point of the wafer.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a system and method for controlling a critical dimension of a wafer edge. Background Art

[0002] During the semiconductor manufacturing process, designers always expect that the critical dimensions of the wafer obtained through the etching process are good and free of anomalies, that is, the error of the critical dimensions of the entire wafer is ±0.1, as shown in Figure 1(a). However, in production practice, due to errors in the main components and various hardware devices used in the etching reaction chamber, the etching rates of specific parts will be different, resulting in deviations between the critical dimensions of the wafer and the expected critical dimensions. As shown in Figure 1(b), the error of the critical dimensions in most areas of the wafer surface is between -0.3 and ±0.1μm, and the error of the critical dimensions at the edge reaches -0.5μm or even -0.7μm. The absolute value of the error is large and the uniformity is poor. Moreover, the change in the critical dimensions from the center of the wafer to the end edge shows a certain trend (such as decrease or increase), such as Figure 2 As shown, the critical dimensions decrease from the center of the wafer toward the end edge.

[0003] The reasons for the different etching rates are: (1) the gap error between the upper electrode and the electrostatic chuck; (2) the inner electrode pore error; (3) the electrostatic chuck surface temperature error; (4) the edge ring wear; (5) the error in wafer transfer, which leads to the spacing error between the wafer and the edge ring.

[0004] In addition, since the etching reaction chamber is composed of various components, with the increase of usage time, changes in the component surface, the formation of by-products, the wear of the Si edge ring, changes in the size of the inner electrode gas hole, etc., will cause abnormalities (Specification Out) at specific points of the critical dimensions of the end edge.

[0005] The existing Si outer electrode generally only has holes for reading the pressure of the wafer area, and no pore structure, or in order to expand the plasma area of ​​the upper electrode, the upper electrode is made of Si material. There are also holes made on the Si inner electrode, and the required gas flows through the center and edge, but in the end edge area of ​​the wafer, there are some specific points (Point) where no gas flows. In addition, there are also edge holes set on the upper gas inlet plate to allow gas to flow through the end edge area, but the relationship of the 360° overall flow direction cannot control the critical dimensions of specific parts.

[0006] The above measures are unable to effectively control the critical dimensions of the wafer edge, resulting in uneven critical dimensions of the wafer edge and failure to obtain a desired wafer profile. Summary of the invention

[0007] In view of the above analysis, the present invention aims to provide a system and method for controlling the critical dimensions of the chip edge, so as to solve the problem that the prior art cannot effectively control the critical dimensions of the chip edge, resulting in uneven critical dimensions of the chip edge and inability to obtain the desired chip contour.

[0008] On the one hand, the present invention provides a system for controlling the critical dimensions of a wafer edge, comprising a top plate, an inner electrode, an outer electrode, an electrostatic chuck for placing a wafer, an edge ring for protecting the wafer edge, a first air intake system and a second air intake system; the first air intake system comprises a first air hole that passes through the top plate and the outer electrode, and the first air hole is used to supply air to the edge of the wafer; the second air intake system comprises a second air hole that passes through the top plate and the inner electrode, and the second air hole is used to supply air to the center of the wafer.

[0009] Based on further improvement of the above system, the first air hole is arranged in the outer electrode toward the center of the wafer, and the angle formed between the contact surface formed by the top plate and the outer electrode and the first air hole in the outer electrode is less than 60°.

[0010] Based on the further improvement of the above system, the diameter of the first air hole is less than or equal to 1 mm.

[0011] Based on a further improvement of the above system, there are multiple first air holes, and the multiple first air holes are evenly distributed along the circumferential direction.

[0012] Based on the further improvement of the above system, the number of the first air holes is 12.

[0013] Based on further improvement of the above system, the first air intake system also includes a plurality of control valves corresponding to the number of the first air holes, and the plurality of control valves are arranged on the upper surface of the top plate or above the top plate to control the gas flow through the first air holes.

[0014] A further improvement based on the above system further includes a control system, and each control valve is connected to the control system to realize the opening and closing of the control valves respectively.

[0015] Based on the further improvement of the above system, it also includes a pressure monitoring device connected to the control system, and the pressure monitoring device is arranged on the air path of the first air intake system and the second air intake system. The control system controls the compensation of the center or edge of the chip through the data monitored by the pressure monitoring device.

[0016] Based on further improvement of the above system, the first air intake system further includes a first master control valve, and the first master control valve is used to control the opening and closing of the first air intake system.

[0017] Based on further improvement of the above system, the second air intake system further includes a second master control valve, and the second master control valve is used to control the opening and closing of the second air intake system.

[0018] Based on a further improvement of the above system, it also includes a first pipeline system connected in parallel with the first air intake system, and the first pipeline system is used to evacuate the first air intake system.

[0019] Based on a further improvement of the above system, it also includes a second pipeline system connected in parallel with the second air intake system, and the second pipeline system is used to evacuate the second air intake system.

[0020] Based on a further improvement of the above system, there are multiple second air holes, and the multiple second air holes are evenly distributed along the circumference.

[0021] Based on further improvement of the above system, the second air intake system also includes a plurality of control valves corresponding to the number of the second air holes, and the plurality of control valves are arranged on the upper surface of the top plate or above the top plate to control whether the gas passes through the second air holes.

[0022] Based on the further improvement of the above system, each control valve is connected to the control system so as to realize the opening and closing of the control valves respectively.

[0023] In another aspect, the present invention further provides a method for controlling a critical dimension of a wafer edge, comprising:

[0024] Determining the type of compensation gas and the opening position of the control valve controlling the first gas hole according to the position of the point to be compensated on the test wafer and the critical dimension compensation value;

[0025] placing a wafer to be etched on a chuck in a process chamber;

[0026] The control system controls the closing of the first, second, third and fourth master control valves to evacuate the cavity;

[0027] Open the first master control valve, the second master control valve and the control valve,

[0028] According to the data monitored by the pressure monitoring device, the control system controls the compensation gas to enter the process chamber to adjust the key dimensions.

[0029] Based on the further improvement of the above method, the critical dimension compensation value is obtained by the following method:

[0030] coating a photoresist layer on a test wafer;

[0031] forming a test pattern on a test mask;

[0032] transferring the test pattern to a test wafer;

[0033] Calculate the mask CD compensation value required for actual mask manufacturing.

[0034] Based on the further improvement of the above method, each test pattern on the mask is transferred to the test wafer by using photolithography and etching processes.

[0035] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0036] (1) The present invention can improve the uniformity of the edge key dimensions of the actual wafer in the subsequent production cycle by arranging air holes at the edge of the top plate and arranging the air holes in the outer electrode to be biased toward the center of the wafer, thereby improving the yield of the device by 1%-2%.

[0037] (2) The present invention controls the angle formed between the contact surface formed by the top plate and the outer electrode and the first air hole in the outer electrode, so that the supplementary gas can be accurately blown to the specific point where the critical dimension of the chip is uneven, thereby achieving precise control of the critical dimension of the end edge of the specific point of the chip.

[0038] (3) The present invention provides a pressure monitoring device, which allows the control system to control compensation, pressure fluctuations in the pipeline, or abnormal alarms for the system, thereby improving the accuracy of adjusting the critical dimensions and the safety of using the system for controlling the critical dimensions of the chip edge.

[0039] (4) By setting the same number of control valves as the pores and setting a control system, the pores can be opened and closed separately.

[0040] (5) By providing a first pipeline system and a second pipeline system for evacuating the air intake system, and by connecting the first pipeline system in parallel with the first air intake system and the second pipeline system in parallel with the second air intake system, it is possible to evacuate the air intake system without causing damage or influence to the pressure monitoring device and the control system due to the evacuation.

[0041] (6) By adopting the method for controlling the critical dimension of the edge of a wafer of the present invention, the compensated CD value is obtained in the central area and the edge area on the actual wafer, and a better CD uniformity is obtained, so that the CD uniformity on the wafer is improved and enhanced.

[0042] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can be obvious from the description or understood by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0044] FIG1(a) is a diagram showing a good critical dimension of a full-shot wafer when the critical dimension of the full-shot wafer is measured after etching;

[0045] FIG1(b) is a diagram showing the Specification Out of the critical dimensions at 9 o'clock when the critical dimensions of the full shot wafer are measured after etching;

[0046] Figure 2 This is a graph showing the changing trend of key dimensions from the center of the wafer to the end edge;

[0047] Figure 3 A schematic diagram of the internal structure of the system according to an embodiment of the present invention;

[0048] Figure 4 Schematic diagram of the gas circuit system of the system according to an embodiment of the present invention.

[0049] Reference numerals:

[0050] 1-top plate; 2-inner electrode; 3-outer electrode; 4-electrostatic chuck; 5-edge ring; 6-wafer; 7-first air hole; 8-second air hole; 9-first master control valve; 10-second master control valve; 11-control valve; 12-control system; 13-pressure monitoring device; 14-third master control valve; 15-fourth master control valve; 16-limiting ring; 17-cavity. DETAILED DESCRIPTION

[0051] Hereinafter, embodiments of the present disclosure will 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 present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0052] Various structural schematic diagrams according to embodiments of the present disclosure are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may further design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0053] In the context of the present disclosure, when a layer / element is referred to as being "on" another layer / element, the layer / element may be directly on the other layer / element or an intervening layer / element may exist therebetween. In addition, if a layer / element is "on" another layer / element in one orientation, the layer / element may be "below" the other layer / element when the orientation is reversed.

[0054] Embodiment 1

[0055] A specific embodiment of the present invention discloses a system for controlling critical dimensions of a wafer edge, such as Figure 3 The system comprises a top plate 1, an inner electrode 2, an outer electrode 3, an electrostatic chuck 4 for placing a wafer, an edge ring 5 for protecting the edge of the wafer, a first gas inlet system and a second gas inlet system.

[0056] The first air intake system is used to supply gas to the edge of the wafer 6. In a possible implementation, the first air intake system includes a first master control valve 9 and a first air hole 7. The first air hole 7 passes through the top plate 1 and the outer electrode 3, and the first air hole 7 is vertically arranged in the top plate and is arranged in the outer electrode 3 toward the center of the wafer. The gas flows to the edge of the wafer through the first air hole, thereby providing compensation gas for the edge of the wafer. Commonly used compensation gases include O2 and C4F8.

[0057] According to the different positions of the points on the wafer where the compensation gas needs to be provided, the angle of the first air hole to the center of the wafer is different, that is, the angle α formed between the contact surface formed by the top plate and the external electrode and the first air hole in the external electrode is different. Therefore, in another possible embodiment, the system for controlling the critical dimension of the edge of the wafer includes a plurality of upper air inlet plates with different values ​​of α, and the air inlet plates with different angles are replaced according to the different positions of the points where the compensation gas needs to be provided. Generally speaking, the value of α is less than 60°.

[0058] The number of first air holes is usually multiple. In order to achieve compensation for the entire edge of the wafer, the multiple first air holes are evenly distributed along the circumferential direction. In a preferred embodiment of the present invention, in order to balance wafer uniformity, adjustment effect, manufacturing cost and practicality, the number of first air holes is selected to be 12, and the diameter is controlled to be less than or equal to 1 mm.

[0059] In most cases, not the entire edge of the chip needs to be compensated, but only certain specific points. Therefore, in one possible implementation, a number of control valves 11 equal to the number of first air holes are provided, and each control valve 11 is connected to a first air hole. Each air hole can be opened or closed individually to adjust the ventilation volume of different parts of the chip edge, thereby indirectly adjusting the chip edge etching effect, or compensating for specific parts.

[0060] The control valve may be a pneumatic valve, or other valve body that can conveniently control the opening and closing of the first air hole.

[0061] The control valve should be located in a position that does not increase the total volume of the system. For example, the control valve can be located on the upper surface of the top plate or above the top plate.

[0062] In addition to supplying gas to the edge of the wafer, the system for controlling the critical dimension of the edge of the wafer of the present invention also includes a second gas intake system for supplying gas to the center of the wafer. The second gas intake system includes a second master control valve 10 and a second gas hole 8, the second gas hole passes through the top plate and the inner electrode, and the second gas hole is vertically arranged in the top plate and in the outer electrode, and the gas flows to the center of the wafer through the second gas hole, thereby providing gas to the center of the wafer.

[0063] The number of the second air holes is usually multiple. In order to achieve uniform etching of the wafer, the multiple second air holes are also evenly distributed along the circumferential direction. In a preferred embodiment of the present invention, in order to balance the uniformity of the wafer, the adjustment effect, the manufacturing cost and the practicality, the number of the second air holes is selected to be 12, and the diameter is less than 1 mm.

[0064] In a possible implementation, a control valve equal to the number of the second air holes is also provided, and the control valve is used to control whether the gas passes through the second air holes, thereby realizing the separate control of the plurality of second air holes. The control valve may be a pneumatic valve, or may be other valve bodies that can conveniently control the opening and closing of the second air holes. The control valve may be provided on the upper surface of the top plate, or may be provided above the top plate.

[0065] In order to facilitate the control of the first air intake system and the second air intake system, the system of the present invention also includes a control system 12, and each control valve 11 is connected to the control system 12 so as to realize the opening and closing of the control valves respectively to control the distribution of gas or the amount of gas entering the reaction chamber, thereby indirectly controlling the plasma distribution and the etching effect of the chip edge, as well as the critical dimension (CD).

[0066] In another possible embodiment, the system for controlling the critical dimensions of the chip edge also includes a pressure monitoring device 13. By providing the pressure monitoring device, the control system can control compensation, pressure fluctuations in the pipeline, or issue abnormal alarms to the system, thereby improving the accuracy of adjusting the critical dimensions and the safety of using the system for controlling the critical dimensions of the chip edge.

[0067] The pressure monitoring device is connected to the control system 12. In addition, the first master control valve 9 and the second master control valve 10 are also connected to the pressure monitoring device 13, and the pressure monitoring device is located between the first and second master control valves and the control system.

[0068] The semiconductor manufacturing process needs to be carried out in a vacuum environment, so the chamber 17 needs to be evacuated before the process is carried out. If no additional pipeline is provided, the pressure monitoring device 13 and the control system 12 will also be evacuated. Therefore, this embodiment also includes a pipeline system for evacuating the air intake system. Figure 4 As shown, the pipeline system includes a first pipeline system and a second pipeline system, the first pipeline system corresponds to the first air intake system and is connected in parallel with the first air intake system; the second pipeline system corresponds to the second air intake system and is connected in parallel with the second air intake system. The first pipeline system is provided with a third master control valve 14, and the second pipeline system is provided with a fourth master control valve 15.

[0069] When the air intake system is evacuated, the first, second, third and fourth master control valves are all closed; after the evacuation is completed and when the key dimensions need to be adjusted, the third and fourth master control valves are closed and the first and second master control valves are opened.

[0070] In order to relatively fix the positions of the inner electrode and the outer electrode, so that the air holes on the top plate are aligned with the air holes on the inner electrode and the outer electrode, in another preferred embodiment of the present invention, a limit ring 16 is provided below the top plate and on the outer side of the outer electrode to limit the relative movement of the inner electrode and the outer electrode, thereby ensuring that the air holes on the top plate are aligned with the air holes on the inner electrode and the outer electrode to form an effective air path.

[0071] Embodiment 2

[0072] Another specific embodiment of the present invention discloses a method for compensating a wafer using the system for controlling a critical dimension of a wafer edge of the first embodiment. The method will be described in detail below.

[0073] After obtaining the position of the point to be compensated on the test wafer and the critical dimension compensation value, the type of compensation gas and the opening position of the control valve controlling the first gas hole are determined. Generally speaking, the compensation gas is O2 and C4F8.

[0074] Next, the wafer to be etched is placed on a chuck in the process chamber. After that, the chamber is evacuated. Specifically, the first, second, third and fourth master control valves need to be closed through the control system.

[0075] After the vacuum degree reaches the process requirement, open the first master control valve, the second master control valve and the control valve of the part to be compensated determined in the above steps, and control the compensation gas to enter the process chamber through the control system according to the data monitored by the pressure monitoring device to adjust the key dimensions.

[0076] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0077] (1) The present invention can improve the uniformity of the edge key dimensions of the actual wafer in the subsequent production cycle by arranging air holes on the edge of the top plate and arranging the air holes in the outer electrode toward the center of the wafer, thereby greatly improving the production efficiency and product yield.

[0078] (2) The present invention controls the angle formed between the contact surface formed by the top plate and the outer electrode and the first air hole in the outer electrode, so that the supplementary gas can be accurately blown to the specific point where the critical dimension of the chip is uneven, thereby achieving precise control of the critical dimension of the end edge of the specific point of the chip.

[0079] (3) The present invention provides a pressure monitoring device, which allows the control system to control compensation, pressure fluctuations in the pipeline, or abnormal alarms for the system, thereby improving the accuracy of adjusting the critical dimensions and the safety of using the system for controlling the critical dimensions of the chip edge.

[0080] (4) By setting the same number of control valves as the pores and setting a control system, the pores can be opened and closed separately.

[0081] (5) By providing a first pipeline and a second pipeline for evacuating the cavity, and by connecting the first pipeline in parallel with the first air intake system and the second pipeline in parallel with the second air intake system, it is possible to evacuate the cavity without causing damage or influence to the pressure monitoring device and the control system due to the evacuation.

[0082] (6) By adopting the method for controlling the critical dimension of the edge of a wafer of the present invention, the compensated CD value is obtained in the central area and the edge area on the actual wafer, and a better CD uniformity is obtained, so that the CD uniformity on the wafer is improved and enhanced.

[0083] In the above description, the technical details of the patterning and etching of each layer are not described in detail. However, those skilled in the art should understand that various technical means can be used to form layers, regions, etc. of desired shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not completely the same as the methods described above. In addition, although the various embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage.

[0084] The embodiments of the present disclosure are described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of the present disclosure. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, a person skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A system for controlling critical dimensions of a wafer edge, characterized in that: It includes a top plate, an inner electrode, an outer electrode, an electrostatic chuck for placing a wafer, an edge ring for protecting the edge of the wafer, a first air intake system and a second air intake system; A recess is provided at the upper portion of one end of the edge ring close to the edge of the wafer, and the side surface of the recess is inclined away from the edge of the wafer. The edge of the wafer extends into the recess and a gap is left between the side surface of the recess. The first air intake system comprises: first air holes penetrating the top plate and the outer electrode, a plurality of control valves corresponding to the number of the first air holes, and a first master control valve; the first air holes are used to provide compensation gas for the edge of the wafer, the first master control valve is used to control the opening and closing of the first air intake system, and each of the control valves is connected to one of the first air holes; The second air intake system comprises a second air hole and a second master control valve penetrating the top plate and the inner electrode, the second air hole is used to supply air to the center of the wafer, and the second master control valve is used to control the opening and closing of the second air intake system; The first air hole is arranged in the outer electrode toward the center of the wafer, and an angle α formed between a contact surface formed by the top plate and the outer electrode and the first air hole in the outer electrode is less than 60°; The system for controlling the critical dimension of the edge of a wafer includes a plurality of upper gas inlet plates having different values ​​of α; Also includes a control system, and a pressure monitoring device connected to the control system; The pressure monitoring device is located between the first master control valve, the second master control valve and the control system; It also includes a first pipeline system connected in parallel with the first air intake system, the first pipeline system is used to evacuate the first air intake system; the first pipeline system is provided with a third master control valve; Also comprising a second pipeline system connected in parallel with the second air intake system, the second pipeline system being used to evacuate the second air intake system; The second pipeline system is provided with a fourth master control valve; The first pipeline system and the second pipeline system are used to prevent the pressure monitoring device and the control system from being evacuated when the cavity is evacuated; The diameter of the first pore is less than or equal to 1 mm; There are multiple first air holes, and the multiple first air holes are evenly distributed along the circumferential direction; The number of the first pores is 12.

2. The system according to claim 1, characterized in that The plurality of control valves are arranged on the upper surface of the top plate or above the top plate, and are used to control the gas flow through the first air holes.

3. The system according to claim 2, characterized in that Each control valve is connected to the control system so as to realize the opening and closing of the control valves respectively.

4. The system according to claim 3, characterized in that The pressure monitoring device is arranged on the gas paths of the first air intake system and the second air intake system, and the control system controls the compensation for the center or edge of the wafer through the data monitored by the pressure monitoring device.

5. The system according to claim 1, characterized in that There are multiple second air holes, and the multiple second air holes are evenly distributed along the circumference.

6. The system according to claim 5, characterized in that The second air intake system further includes a plurality of control valves corresponding to the number of the second air holes. The plurality of control valves are disposed on the upper surface of the top plate or above the top plate and are used to control whether the gas passes through the second air holes.

7. The system according to claim 6, characterized in that Each control valve is connected to the control system so as to realize the opening and closing of the control valves respectively.

8. A method for controlling a critical dimension of a wafer edge, characterized in that: A system according to any one of claims 1 to 7, comprising: Determining the type of compensation gas and the opening position of the control valve controlling the first gas hole according to the position of the point to be compensated on the test wafer and the critical dimension compensation value; placing a wafer to be etched on a chuck in a process chamber; The control system controls the closing of the first, second, third and fourth master control valves to evacuate the cavity; Open the first master control valve, the second master control valve and the control valve, According to the data monitored by the pressure monitoring device, the control system controls the compensation gas to enter the process chamber to adjust the key dimensions.

9. The method according to claim 8, characterized in that The critical dimension compensation value is obtained by the following method: coating a photoresist layer on a test wafer; forming a test pattern on a test mask; transferring the test pattern to a test wafer; Calculate the mask CD compensation value required for actual mask manufacturing.

10. The method according to claim 9, characterized in that Each test pattern on the mask is transferred to the test wafer using photolithography and etching processes.

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