Electrode and semiconductor pre-cleaning equipment

Abstract

The invention provides an electrode, the electrode is applied to semiconductor pre-cleaning equipment, the electrode is located above a plate electrode, the electrode comprises an electrode main body, and the electrode main body comprises an air inlet and an inner cavity communicated with the air inlet; wherein the inner contour of the longitudinal section of the inner cavity is in an axial symmetry pattern with the central axis as the symmetry axis, the inner cavity comprises a cavity inner wall, and the diameter of the inner cavity is increased in a non-linear mode in the direction from the air inlet to the plate electrode. The invention further comprises a semiconductor pre-cleaning device, and the semiconductor pre-cleaning device comprises the electrode. When the semiconductor pre-cleaning equipment with the electrode is used for pre-cleaning a wafer, the discharge efficiency, the air pressure range and the free radical reaction range can be considered, and the density and energy of high-energy electrons are enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of electrodes for semiconductor pre-cleaning equipment, and in particular to an electrode and semiconductor pre-cleaning equipment. Background Art

[0002] Before the epitaxial deposition step in semiconductor manufacturing, it is often necessary to remove the oxide layer on the surface of the substrate, such as silicon oxide, through a pre-cleaning step. Common pre-cleaning methods include dry and wet pre-cleaning. Dry pre-cleaning is to generate plasma and free radicals by exciting process gas. The free radicals react chemically with the oxide on the surface of the substrate to generate compounds, which are then decomposed and volatilized by heating to achieve the purpose of cleaning. Dry pre-cleaning has the advantages of simple structure, simple process, and high cleaning efficiency. It is currently a widely used pre-cleaning method. Its key structure is the plasma source. The most widely used method is to use the hollow cathode discharge effect to generate plasma and free radicals. There are two types of electrode structures used in the prior art. One is a straight electrode with equal width at the top and bottom, and the other is a conical electrode with a small top and a large bottom. However, the straight electrode has the disadvantages of small gas pressure change and uneven distribution of free radicals. Although the conical electrode overcomes the disadvantages of the straight electrode, it has the problem of metal particle contamination caused by the need to apply a higher breakdown voltage, which will have a certain impact on pre-cleaning. Summary of the invention

[0003] The purpose of the present invention is to provide an electrode and semiconductor pre-cleaning equipment to solve the problems of small gas pressure change, uneven free radical distribution, metal particle contamination, etc. existing in the electrode of the prior art.

[0004] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0005] An electrode is used in semiconductor pre-cleaning equipment, the electrode is located above a flat plate electrode, and the electrode comprises:

[0006] An electrode body, the electrode body comprising an air inlet and an inner cavity communicating with the air inlet;

[0007] The inner contour of the longitudinal section of the inner cavity is an axisymmetric figure with the central axis as the axis of symmetry, and the inner cavity includes an inner wall of the cavity, and the diameter of the inner cavity increases nonlinearly from the air inlet to the flat electrode.

[0008] Optionally, the inner contour of the longitudinal section of the inner cavity is a tower-shaped structure, the longitudinal section of the inner wall of the cavity is stepped, and the stepped inner wall of the cavity includes a vertical wall along the longitudinal direction of the inner cavity and a horizontal wall along the transverse direction of the inner cavity.

[0009] Optionally, the stepped inner wall of the cavity includes at least three steps, and each step includes the vertical wall and the horizontal wall connected to each other.

[0010] Optionally, the heights of the vertical walls of each level of the steps are equal, and the widths of the transverse walls of each level of the steps are equal.

[0011] Optionally, the heights of the vertical walls of each level of the steps are equal, and the widths of the horizontal walls of each level of the steps increase step by step in a direction from the air inlet to the flat electrode.

[0012] Optionally, the widths of the transverse walls of each level of the steps are equal, and the heights of the vertical walls of each level of the steps increase step by step in a direction from the air inlet to the flat electrode.

[0013] Optionally, in a direction from the air inlet to the flat electrode, the width of the horizontal arm and the height of the vertical wall of each level of the steps increase step by step.

[0014] Optionally, a chamfer is provided at the connection between the vertical wall and the horizontal wall.

[0015] Optionally, the inner contour of the longitudinal section of the inner cavity is a bell-shaped structure.

[0016] Optionally, the inner wall of the cavity is a bell-shaped surface, and the center of curvature of each point on the surface points to the central axis of the inner cavity.

[0017] Optionally, the curvature of the curved surface decreases in the direction from the air inlet to the flat electrode.

[0018] Optionally, the inner contour of the cross section of the electrode is at least one of a circle and a regular polygon with an even number of sides.

[0019] The present invention also provides a semiconductor pre-cleaning device, comprising:

[0020] the electrode;

[0021] A flat plate electrode, the flat plate electrode is arranged below the electrode;

[0022] A process chamber is arranged below the flat electrode.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] (1) The present invention designs the diameter of the inner cavity of the electrode to increase nonlinearly in the direction from the air inlet to the flat electrode, thereby increasing the range of gas pressure variation, while increasing the range and concentration of generated free radicals and improving the pre-cleaning effect.

[0025] (2) By designing the longitudinal section of the inner cavity into a tower shape, the structure has a gradient change in diameter and can ensure the parallelism of the electrode walls within a certain range along the axial direction, thereby increasing the range of gas pressure change and ensuring good discharge efficiency.

[0026] (3) By designing the longitudinal section of the inner cavity to be bell-shaped, the contour of the inner wall of the cavity is a curve with the center of curvature pointing to the central axis of the inner cavity. This structure not only retains the gradient change of the diameter, but also the movement direction of the electrons changes continuously due to the change of the curvature. The movement direction of the electrons is concentrated toward the center of the curvature, thereby increasing the electron density and energy density in this area, allowing the ignition discharge to occur at a lower voltage. Moreover, as the bell-shaped structure tends to be parallel, it is also beneficial to the enhancement of the electron energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the description. Obviously, the drawings described below are an embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work:

[0028] Figure 1 A schematic structural diagram of a semiconductor pre-cleaning device 100 provided by the present invention;

[0029] Figure 2 A schematic longitudinal section diagram of a first embodiment of an electrode 102 provided by the present invention;

[0030] Figure 3 (a)- Figure 3 (d) is a schematic diagram of the size relationship between the vertical wall 134 and the horizontal wall 132 of the three-step ladder provided by the present invention;

[0031] Figure 4 This is a schematic longitudinal cross-sectional view of a second embodiment of the electrode 102 provided by the present invention. DETAILED DESCRIPTION

[0032] The scheme proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the implementation method of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the accompanying drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no technical substantive significance. Any structural modification, change in proportional relationship or adjustment of size, without affecting the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present invention.

[0033] Semiconductor equipment generally includes a wafer front-end module (EFEM), a load lock chamber (Load Lock), a wafer transfer chamber (TM), and a process chamber (PM) connected in sequence. The wafer front-end module transports the wafer to the load lock chamber for pumping negative pressure, and then, under the action of the robot in the wafer transfer chamber, the wafer is moved to the wafer transfer chamber, and then transferred to the process chamber for corresponding process processing. According to different semiconductor processes, it can be divided into pre-cleaning, epitaxy, etching, ion implantation and other processes, and different processes correspond to different process chambers.

[0034] Figure 1 A schematic diagram of the structure of the semiconductor pre-cleaning device 100 provided by the present invention is shown in FIG. Figure 1As shown, the semiconductor pre-cleaning equipment 100 includes an electrode assembly, a distribution assembly and a process chamber, and an exhaust pump (not shown). The electrode assembly includes an electrode 102 and a flat electrode 104. The electrode 102 is located above the flat electrode 104. There is a certain distance between the electrode 102 and the flat electrode 104. The flat electrode 104 is located directly below the electrode 102 and is provided with a plurality of gas channels 106. When the reaction gas passes through the electrode 102, it is excited to generate plasma and free radicals. The free radicals are not charged and will not be bound by the electric field. They enter the process chamber through the plurality of gas channels 106 of the flat electrode 104 below to react with the oxide on the surface of the wafer, thereby achieving pre-cleaning of the wafer surface. The distribution assembly includes an upper distribution plate 108 and a lower distribution plate 112. The upper distribution plate 108 is fixedly connected to the lower surface of the flat electrode 104 and is located between the flat electrode 104 and the lower distribution plate 112. The upper distribution plate 108 is provided with a plurality of gas channels 110, the size of which can be adjusted to provide a controllable and uniform fluid distribution on the lower distribution plate 112 below. The lower distribution plate 112 is located below the gas channel 110 and is provided with a plurality of gas channels 114, the size of which can be adjusted to provide a controllable and uniform fluid distribution in the process chamber. The process chamber is arranged below the distribution assembly, and includes a pedestal 118, a cavity and a bushing 116. The pedestal 118 is arranged in the cavity and is used to support the wafer. The bushing 116 is arranged on the inner surface of the side wall 120 of the cavity and is arranged around the pedestal 118, and is used to evenly distribute the process gas on the surface of the wafer, and the process gas after the process treatment is discharged from the cavity; wherein, a lifting device 122 is arranged at the bottom of the cavity, and the pedestal 118 is arranged at the top of the lifting device 122. The height of the pedestal 118 is changed by the lifting device 122, so that the pedestal 118 is lowered, and the wafer is supported by the lifting pins 124, and the wafer is separated from the pedestal 118 so that the robot can take the wafer. The side wall 120 of the cavity is provided with an exhaust port 126, which is used to discharge the process gas after the process treatment from the cavity, and the pump is connected to the exhaust port 126 of the cavity through an exhaust pipeline.

[0035] Figure 2 and Figure 4 is a schematic diagram of the electrode 102 of the present invention, as shown Figure 2 , 4As shown, the electrode 102 includes an electrode body, the electrode body includes an air inlet 128 and an inner cavity connected to the air inlet 128, the inner contour of the longitudinal section of the inner cavity is an axisymmetric figure with the central axis M as the symmetry axis, the inner cavity includes a cavity inner wall 130, and the diameter of the inner cavity increases nonlinearly from the air inlet 128 to the flat electrode 104. Wherein, the direction from the air inlet 128 to the flat electrode 104 is the direction from top to bottom along the central axis M, and the diameter is the width of the inner contour of the inner cavity along the transverse direction (i.e., the direction perpendicular to the central axis M). Optionally, the air inlet 128 is arranged above the inner cavity, and the outer contour of the electrode 102 is cylindrical or rectangular.

[0036] Figure 2 FIG. 1 shows a schematic longitudinal section diagram of a first embodiment of an electrode 102 provided by the present invention. Figure 2 As shown, the inner contour of the longitudinal section of the inner cavity is a tower structure, and the longitudinal section of the inner wall 130 of the cavity is stepped. The stepped inner wall 130 of the cavity includes a vertical wall 134 along the longitudinal direction of the inner cavity and a horizontal wall 132 along the transverse direction of the inner cavity. The design of the tower structure ensures that the diameter increases nonlinearly along the central axis M, and the vertical walls 134 opposite to each other in the transverse direction are parallel to each other. The parallel vertical walls 134 make the electrons e move back and forth between the sheaths close to the vertical walls, that is, produce a "pendulum effect", increase the energy of the electrons e, and thus excite the reaction gas to produce plasma. At the same time, the range of change of gas pressure is increased, the uniformity and concentration of the generated free radicals are improved, and the discharge efficiency is improved.

[0037] Preferably, a chamfer 136 is provided at the connection between the vertical wall 134 and the horizontal wall 132 to prevent arc discharge caused by charge accumulation there.

[0038] Preferably, the stepped chamber inner wall 130 includes at least three steps, and each step includes the vertical wall 134 and the horizontal wall 132 connected to each other.

[0039] Take the three-step ladder as an example. Figure 3 (a)- Figure 3 (d) shows a schematic diagram of the size relationship between the vertical wall 134 and the horizontal wall 132 of the three-step ladder provided by the present invention, as shown in FIG. Figure 3 As shown in (a), in the direction from the air inlet 128 to the flat electrode 104, the heights of the vertical walls 134 of the three steps are L1, L2, and L3, respectively. In this embodiment, L1=L2=L3. The widths of the horizontal walls 132 of the three steps are W1, W2, and W3, respectively. In this embodiment, W1=W2=W3.

[0040] like Figure 3As shown in (b), the heights of the vertical walls 134 of the three - stage steps are L1, L2, and L3 respectively. In this embodiment, L1 = L2 = L3. The widths of the horizontal walls 132 of the three - stage steps are W1, W2, and W3 respectively. In this embodiment, they gradually increase in the direction from the air inlet 128 to the flat electrode 104, that is, W1 < W2 < W3. The electrode 102 gradually becomes larger in the width direction, which can further increase the range of air pressure change and improve the uniformity and concentration of the generated free radicals.

[0041] As Figure 3 As shown in (c), the widths of the horizontal walls 132 of the three - stage steps are W1, W2, and W3 respectively. In this embodiment, W1 = W2 = W3. The heights of the vertical walls 134 of the three - stage steps are L1, L2, and L3 respectively, and they gradually increase in the direction from the air inlet 128 to the flat electrode 104, that is, L1 < L2 < L3. The electrode 102 gradually becomes larger in the height direction, which can further improve the energy of the electrons.

[0042] As Figure 3 As shown in (d), in this embodiment, in the direction from the air inlet 128 to the flat electrode 104, the widths of the horizontal walls 132 of the three - stage steps are W1, W2, and W3 respectively, and the heights of the vertical walls 134 are L1, L2, and L3 respectively, and both gradually increase, that is, the width W1 < W2 < W3 and the height L1 < L2 < L3.

[0043] Of course, only three - stage steps are taken as an example for illustration here. The number of steps of the tower - shaped structure of the present invention is not limited to three, and the widths of the horizontal walls 132 and the heights of the vertical walls 134 follow corresponding changes.

[0044] Figure 4 It is a longitudinal sectional view of the second embodiment of the electrode 102 provided by the present invention. As Figure 4As shown, different from the first embodiment, the inner contour of the longitudinal section of the inner cavity is a bell-shaped structure, the inner wall 130 of the cavity is a central curved surface, and the center of curvature of each point on the curved surface points to the central axis M of the inner cavity. From the air inlet 128 to the flat electrode 104, the curvature of the curved surface decreases, and the curved surfaces opposite to the bell-shaped structure tend to be parallel on the side away from the air inlet 128. By designing the longitudinal section of the inner cavity to be bell-shaped, and the contour of the inner wall of the cavity is a curve with the center of curvature pointing to the central axis of the inner cavity, the structure not only retains the nonlinear increase of the diameter, but also the movement direction of the electrons e due to the change of curvature constantly changes, and the movement direction of the electrons e is concentrated in the direction of the center of curvature, thereby increasing the electron density and energy density in this area, so that the ignition discharge can occur at a lower voltage, and as the curved surfaces of the bell-shaped structure tend to be parallel, the energy of the electrons e is further enhanced.

[0045] The inner contour of the cross section of the electrode 102 is at least one of a circle and a regular polygon with an even number of sides.

[0046] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or device including the elements. In addition, the term "connection" herein means that A and B are directly connected, or that A and B are indirectly connected, such as A and B are connected through C, or even through more components such as C and D, and A and B can be connected in one piece, or in separate pieces, or removable, or fixed. The term "optional" herein means that the technical feature can be combined or not combined with any feature in the text.

[0047] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. An electrode, applied to semiconductor pre-cleaning equipment, the electrode is located above a flat plate electrode, characterized in that: The electrode comprises: An electrode body, the electrode body comprising an air inlet and an inner cavity communicating with the air inlet; The inner contour of the longitudinal section of the inner cavity is an axisymmetric figure with the central axis as the axis of symmetry, and the inner cavity includes an inner wall of the cavity, and the diameter of the inner cavity increases nonlinearly from the air inlet to the flat electrode.

2. The electrode according to claim 1, characterized in that The inner contour of the longitudinal section of the inner cavity is a tower-shaped structure, the longitudinal section of the inner wall of the cavity is stepped, and the stepped inner wall of the cavity includes a vertical wall along the longitudinal direction of the inner cavity and a horizontal wall along the transverse direction of the inner cavity.

3. The electrode according to claim 2, characterized in that The stepped cavity inner wall includes at least three steps, and each step includes the vertical wall and the horizontal wall connected to each other.

4. The electrode according to claim 3, characterized in that The heights of the vertical walls of the steps at each level are equal, and the widths of the transverse walls of the steps at each level are equal.

5. The electrode according to claim 3, characterized in that The heights of the vertical walls of each level of the steps are all equal, and the widths of the transverse walls of each level of the steps increase step by step in a direction from the air inlet to the flat electrode.

6. The electrode according to claim 3, characterized in that The widths of the transverse walls of each level of the steps are equal, and the heights of the vertical walls of each level of the steps increase step by step in the direction from the air inlet to the flat electrode.

7. The electrode according to claim 3, characterized in that In the direction from the air inlet to the flat electrode, the width of the transverse wall and the height of the vertical wall of each level of the steps increase step by step.

8. The electrode according to claim 3, characterized in that A chamfer is provided at the connection between the vertical wall and the transverse wall.

9. The electrode according to claim 1, characterized in that The inner contour of the longitudinal section of the inner cavity is a bell-shaped structure.

10. The electrode according to claim 9, characterized in that The inner wall of the cavity is a bell-shaped curved surface, and the center of curvature of each point on the curved surface points to the central axis of the inner cavity.

11. The electrode according to claim 9, characterized in that In a direction from the air inlet to the flat electrode, the curvature of the curved surface becomes smaller.

12. The electrode according to claim 1, characterized in that The inner contour of the cross section of the electrode is at least one of a circle and a regular polygon with an even number of sides.

13. A semiconductor pre-cleaning device comprising: The electrode according to any one of claims 1 to 12; A flat plate electrode, the flat plate electrode is arranged below the electrode; A process chamber is arranged below the flat electrode.

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