Method for forming semiconductor structure

Abstract

A method for forming a semiconductor structure includes: providing a substrate; forming a dielectric layer on the substrate; forming an opening in the dielectric layer; forming an anti-reflection coating in the opening, and applying alternating current around the substrate when forming the anti-reflection coating. Since alternating current is applied around the substrate when forming the anti-reflection coating, the alternating current will generate a magnetic field force perpendicular to the surface of the substrate, and since some particles in the anti-reflection coating material have weak charges, when holes or bubble defects are formed in the anti-reflection coating material filled in the opening, the particles with weak charges in the anti-reflection coating material can squeeze the holes or bubble defects under the action of the magnetic field force, so that the holes or bubble defects can be reduced or eliminated, so that the formed anti-reflection coating can well fill the opening.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a method for forming a semiconductor structure. Background Art

[0002] With the continuous development of integrated circuit manufacturing technology, the characteristic size of semiconductor chips continues to shrink; at the same time, as the number of transistors in the chip continues to increase and the functions become more and more powerful, the metal wiring of the chip is becoming thinner and thinner, and the layers are increasing. This makes the resistance-capacitance (RC) delay caused by the wiring resistance and the capacitance of the dielectric layer between the wirings have an increasingly greater impact on the chip speed, even exceeding the gate delay that determines the speed of the transistor itself.

[0003] In order to solve the problem of resistance-capacitance delay (RC delay), the industry has taken the following measures: First, use low-dielectric materials (dielectric constant less than 3.0) that meet IC technology, so that the dielectric constant of the dielectric layer between multiple metal interconnects is lower than that of silicon, thereby reducing parasitic capacitance; second, use copper instead of aluminum as the conductive material for interconnects in semiconductor components to reduce resistance; compared with aluminum, copper has a small resistivity, a high melting point, strong resistance to electromigration, and can carry higher current density. In addition, since copper can be made thinner, the use of copper process can also reduce capacitance and power consumption, while increasing the packaging density of components.

[0004] Since copper is difficult to etch, the etching technology traditionally used to form aluminum metal wiring is not applicable to copper. For this reason, a new wiring method called dual damascene structure has been developed. The so-called dual damascene structure process refers to: first forming interconnected grooves and through holes in the dielectric layer, then depositing copper in the interconnected grooves and through holes by electroplating or chemical copper plating, and then using chemical mechanical polishing (CMP) to grind away the overfilled copper.

[0005] In the manufacturing process of the existing dual damascene structure, there is a problem that the anti-reflective coating cannot fill the through hole or opening well, which affects the morphology of the formed groove. Summary of the invention

[0006] The technical problem to be solved by the present invention is how to enable the anti-reflection coating to fill the through hole or opening well.

[0007] The present invention provides a method for forming a semiconductor structure, comprising:

[0008] providing a substrate;

[0009] forming a dielectric layer on the substrate;

[0010] forming an opening in the dielectric layer;

[0011] An anti-reflection coating is formed in the opening, and an alternating current is applied around the substrate during the formation of the anti-reflection coating.

[0012] Optionally, the anti-reflection coating is formed in a coating chamber, wherein a suction cup for adsorbing the substrate is provided in the coating chamber, the coating chamber is surrounded by a chamber wall, and a coil surrounding the suction cup is provided on a side wall of the chamber wall.

[0013] Optionally, when forming the anti-reflective coating, the substrate is placed on the suction cup, and the suction cup controls the rotation of the substrate. When the substrate rotates, the anti-reflective coating material is sprayed from above the substrate, and at the same time, alternating current is applied to the coil, and the alternating current generates a magnetic field force perpendicular to the surface of the substrate in the coating chamber.

[0014] Optionally, the voltage of the alternating current is 180-380V and the frequency is 0.5-50Hz.

[0015] Optionally, the number of turns of the coil is greater than 100, the diameter of the coil is greater than the diameter of the substrate on the suction cup, and the distribution length of the coil along the side wall is greater than the total thickness of the suction cup and the substrate on the suction cup.

[0016] Optionally, the distribution length of the coil is 80mm-500mm, and the diameter of the coil is 350mm-800mm.

[0017] Optionally, the method further includes the steps of: removing the anti-reflective coating to expose the opening again; and filling the opening with a conductive material to form a conductive connection structure.

[0018] Optionally, the opening is a through hole located in the dielectric layer; after forming an anti-reflective coating in the through hole, etching away a portion of the thickness of the dielectric layer and removing the anti-reflective coating, forming a groove connected to the through hole in the dielectric layer; filling the groove and the through hole with a conductive material to form a dual Damascene structure.

[0019] Optionally, after forming the anti-reflective coating in the through hole, the method further includes: forming a patterned photoresist layer on the dielectric layer, the patterned photoresist layer having a second opening exposing the through hole and a portion of the dielectric layer around the through hole; using the patterned photoresist layer as a mask, etching away a portion of the thickness of the dielectric layer and removing the anti-reflective coating along the second opening, and forming a groove in the dielectric layer connected to the through hole.

[0020] Optionally, the substrate further comprises a connection metal pad, and the dual Damascus structure is connected to the connection metal pad.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0022] The method for forming a semiconductor structure of the present invention comprises: providing a substrate; forming a dielectric layer on the substrate; forming an opening in the dielectric layer; forming an anti-reflection coating in the opening, and applying alternating current around the substrate when forming the anti-reflection coating. Since alternating current is applied around the substrate when forming the anti-reflection coating, the alternating current will generate a magnetic field force perpendicular to the surface of the substrate. Since some particles in the anti-reflection coating material have weak charges, when holes or bubble defects are formed in the anti-reflection coating material filled in the opening, the particles with weak charges in the anti-reflection coating material can squeeze the holes or bubble defects under the action of the magnetic field force, so that the holes or bubble defects can be reduced or disappeared, so that the formed anti-reflection coating can fill the opening well. When a groove connected to the opening (or through hole) is subsequently formed by etching away a portion of the thickness of the dielectric layer or when the anti-reflection coating is directly etched away to expose the opening again, the anti-reflection coating filled in the opening will not affect the etching process, so that the formed groove or the re-exposed opening has a good sidewall morphology. And because alternating current is applied, the direction of the current changes at intervals, so that the direction of the generated magnetic field force will also change accordingly, so that the particles with weak charges in the anti-reflective coating material can squeeze the holes or bubble defects from above and below in turn under the action of the magnetic field force, so that the holes or bubble defects can be reduced or eliminated faster or better. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1-11 It is a structural schematic diagram of the formation process of the semiconductor structure according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] As mentioned in the background art, during the manufacturing process of the existing dual damascene structure, there is a problem that the anti-reflective coating cannot fill the through hole or opening well, thus affecting the morphology of the formed groove.

[0025] Research has found that the existing method for making a dual damascene structure includes a via first method (Via First), which includes the steps of: providing a substrate; forming a dielectric layer on the substrate; forming a via (or opening) in the dielectric layer; filling the via with an anti-reflective coating; forming a patterned photoresist layer on the dielectric layer, the patterned photoresist layer having an opening that exposes the via and a portion of the dielectric layer around the via; using the patterned photoresist layer as a mask, etching away a portion of the thickness of the dielectric layer and removing the anti-reflective coating, forming a groove in the dielectric layer that is connected to the via; filling the groove and the via with metal to form a dual damascene structure.

[0026] Further research found that due to the high aspect ratio of the existing through-holes, when the anti-reflective coating for filling the through-holes is formed by a spin coating process, defects such as holes or bubbles are easily formed in the anti-reflective coating formed in the through-holes, so that the through-holes cannot be filled well. When the dielectric layer is subsequently etched to form a channel, the anti-reflective coating with defects such as air gaps or bubbles will affect the uniformity of etching, thereby affecting the morphology of the formed channel. Poor morphology of the groove will affect the electrical properties of the dual damascene structure formed in the groove and the through-hole.

[0027] To this end, the present invention provides a method for forming a semiconductor structure of the present invention, comprising: providing a substrate; forming a dielectric layer on the substrate; forming an opening in the dielectric layer; forming an anti-reflective coating in the opening, and applying alternating current around the substrate when forming the anti-reflective coating. Since alternating current is applied around the substrate when forming the anti-reflective coating, the alternating current will generate a magnetic field force perpendicular to the surface of the substrate. Since some particles in the anti-reflective coating material have weak charges, when holes or bubble defects are formed in the anti-reflective coating material filled in the opening, the particles with weak charges in the anti-reflective coating material can squeeze the holes or bubble defects under the action of the magnetic field force, so that the holes or bubble defects can be reduced or disappeared, so that the formed anti-reflective coating can fill the opening well. When a groove connected to the opening (or through hole) is subsequently formed by etching away a portion of the thickness of the dielectric layer or when the anti-reflective coating is directly etched away to expose the opening again, the anti-reflective coating filled in the opening will not affect the etching process, so that the formed groove or the re-exposed opening has a good sidewall morphology. And because alternating current is applied, the direction of the current changes at intervals, so that the direction of the generated magnetic field force will also change accordingly, so that the particles with weak charges in the anti-reflective coating material can squeeze the holes or bubble defects from above and below in turn under the action of the magnetic field force, so that the holes or bubble defects can be reduced or eliminated faster or better.

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. When describing the embodiments of the present invention in detail, for the sake of convenience, the schematic diagrams will not be partially enlarged according to the general proportion, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0029] refer to Figure 1 , providing a substrate 201 ; forming a dielectric layer 202 on the substrate 201 .

[0030] In one embodiment, the base 200 includes a semiconductor substrate and an underlying dielectric layer located on the semiconductor substrate, wherein semiconductor devices such as transistors are formed in the semiconductor substrate, and metal connection pads are formed in the underlying dielectric layer, and the metal connection pads can be electrically connected to the semiconductor devices in the semiconductor substrate.

[0031] The material of the semiconductor substrate may be silicon (Si), germanium (Ge), or silicon germanium (GeSi), silicon carbide (SiC); it may also be silicon on insulator (SOI), germanium on insulator (GOI); or it may also be other materials, such as III-V group compounds such as gallium arsenide. In this embodiment, the material of the semiconductor substrate 201 is silicon. The semiconductor substrate is doped with certain impurity ions as needed, and the impurity ions may be N-type impurity ions or P-type impurity ions.

[0032] In other embodiments of the present invention, the base may be directly a semiconductor substrate, and a dielectric layer is formed on the surface of the semiconductor substrate.

[0033] The dielectric layer 202 is formed on the substrate 201 by a deposition process, and the thickness of the dielectric layer 202 may be 2000 to 3000 angstroms. The material of the dielectric layer 202 may be silicon oxide, silicon nitride, silicon oxynitride, fluorine-doped silicon glass (FSG), low dielectric constant (K≤3.5) material, other suitable materials and / or combinations thereof. In one embodiment, the low dielectric constant material may be SiCOH.

[0034] refer to Figure 2 or Figure 3 , an opening 203 is formed in the dielectric layer 202 .

[0035] The opening 203 is an opening with a high aspect ratio (aspect ratio greater than 2:1). In one embodiment, the dielectric layer 202 is etched using an anisotropic dry etching process (which may be a plasma etching process) to form the opening 203 in the dielectric layer 202, and the opening 203 is located above the metal connection pad.

[0036] In one embodiment, please refer to Figure 2 The opening 203 is a through hole formed in the dielectric layer 202, the number of the through holes is 1 or more (greater than or equal to 2), and the through hole is subsequently used as a part of the dual damascene opening. The through hole can penetrate the thickness of the dielectric layer 202, or the depth of the through hole is less than the thickness of the dielectric layer 202, and metal can be subsequently filled in the dual damascene opening to form a dual damascene structure.

[0037] In another embodiment, please refer to Figure 3The opening 203 is located in a groove in the dielectric layer 202 , and a conductive material is subsequently filled in the groove to form a conductive connection structure (such as a plug).

[0038] refer to Figure 4 or Figure 5 , Figure 4 exist Figure 2 Based on Figure 5 exist Figure 3 Based on the opening 203 (reference Figure 2 or Figure 3 ) is formed in the anti-reflection coating 205, and when forming the anti-reflection coating 205, an alternating current is applied around the substrate 201.

[0039] The purpose of forming the anti-reflective coating 205 is: on the one hand, when other material layers (such as a photoresist layer or a mask layer) need to be formed on the dielectric layer 202 later, the other material layers can have a flat surface; on the other hand, when a photoresist layer is subsequently formed on the dielectric layer 202, when the photoresist layer is exposed, the reflection of light can be reduced, the dimensional accuracy of the pattern formed in the photoresist layer can be improved, and a good side wall morphology can be maintained.

[0040] In one embodiment, the material of the anti-reflective coating 205 may be a bottom anti-reflective coating (BARC).

[0041] In one embodiment, reference Figure 6 The anti-reflective coating 205 is formed in a coating chamber 31, wherein the coating chamber 31 has a suction cup 304 for adsorbing the substrate 201, and the coating chamber 31 is surrounded by a chamber wall 301, and a coil 302 surrounding the suction cup 304 is arranged on the side wall of the chamber wall 301, and an alternating current is applied to the coil 302.

[0042] The coating chamber 31 is a part of the coating device. Before the anti-reflection coating is formed in the opening 203 in the dielectric layer 202 of the substrate 201, the substrate 201 formed with the dielectric layer 202 is first placed on the suction cup 304 in the coating chamber 31. The suction cup 304 fixes the substrate 201 by vacuum adsorption. The suction cup 304 also controls the rotation of the substrate 201. When the substrate 201 rotates, the (liquid) anti-reflection coating material is sprayed from the top of the substrate 201. At the same time, an alternating current is applied to the coil 302. The alternating current generates a magnetic field force perpendicular to the surface of the substrate 201 in the coating chamber until the surface of the substrate 201 is formed at the opening 203 (reference Figure 2 or Figure 3) is formed in the substrate 201 (or the suction cup 304). When the anti-reflection coating 205 is formed, an alternating current is applied around the substrate 201 (or the suction cup 304), and the alternating current (in the coating chamber) generates a magnetic field force perpendicular to the surface of the substrate 201. Since some particles in the anti-reflection coating material have a weak charge, when holes or bubble defects are formed in the anti-reflection coating material filled in the opening, the particles with a weak charge in the anti-reflection coating material can squeeze the holes or bubble defects under the action of the magnetic field force 303, so that the holes or bubble defects can be reduced or disappeared, so that the formed anti-reflection coating 205 can fill the opening 203 well. When a portion of the dielectric layer is subsequently etched away to form a groove connected to the opening (or through hole) or when the anti-reflection coating is directly etched away to expose the opening again, the anti-reflection coating filled in the opening will not affect the etching process, so that the formed groove or the re-exposed opening has a good sidewall morphology. Furthermore, since alternating current is applied, the direction of the current changes at intervals, so that the direction of the generated magnetic field force 303 also changes accordingly, so that the particles with weak charges in the anti-reflective coating material can squeeze the holes or bubble defects from above and below in turn under the action of the magnetic field force 303, so that the holes or bubble defects can be reduced or eliminated faster or better. Specifically, when the direction of the alternating current in the coil 302 is Figure 6 As shown by the arrow in the middle, the corresponding magnetic field force 303 is downward, and when the direction of the alternating current in the coil 302 is Figure 7 As shown by the arrow in the middle, the corresponding magnetic field force 303 is upward. It should be noted that Figure 4 and Figure 5 The magnetic field forces 303 in two different directions are illustrated. Figure 4 It shows that the magnetic field force 303 generated is perpendicular to the surface of the substrate 201 and downward. Figure 5 It is illustrated that the generated magnetic field force 303 is perpendicular to the surface of the substrate 201 and is directed upward.

[0043] In one embodiment, the voltage of the coil alternating current is 180-380V, which may be 180V, 200V, 250V, 280V, 300V, 350V, or 380V, and the frequency is 0.5-50Hz, which may be 0.5Hz, 1Hz, 2Hz, 5Hz, 10Hz, 20Hz, 30Hz, 40Hz, or 50Hz, so that when the anti-reflective coating 205 is formed, the speed and efficiency of reducing or eliminating the holes or bubble defects in the anti-reflective coating material filled in the opening 203 are further improved. In a specific embodiment, the voltage of the coil alternating current is 180-380V, and the frequency is 0.5Hz-2HZ, so the current changes direction every two seconds, and the magnetic field force 303 generated also changes direction every 2 seconds-0.5 seconds (for example, the magnetic field force 303 changes from a direction perpendicular to the surface of the substrate 201 downward to a direction perpendicular to the surface of the substrate 201 upward, or from a direction perpendicular to the surface of the substrate 201 upward to a direction perpendicular to the surface of the substrate 201 downward), so that the time period of the current direction change is not too fast or too slow, so that the particles with weak charges in the anti-reflective coating material can squeeze the holes or bubble defects from the top and bottom in turn under the action of the magnetic field force 303, so that the speed and efficiency of reducing or disappearing the holes or bubble defects in the anti-reflective coating material can be more effectively improved. In one embodiment, the number of turns of the coil is greater than 100, and the diameter D of the coil (refer to Figure 7 ) is larger than the diameter of the substrate 201 on the suction cup, and the distribution length L of the coil 302 along the side wall of the chamber wall 301 (reference Figure 7 ) is greater than the total thickness of the suction cup and the substrate on the suction cup, so that when the anti-reflection coating 205 is formed, the anti-reflection coating material filled in the opening 203 is reduced or disappeared faster or more effectively. In a specific embodiment, the material of the coil 302 can be a copper wire or an aluminum wire, and the coil 302 can be set on the inner wall surface, the outer wall surface or the chamber wall of the chamber wall 301. In other embodiments, the coil 302 can also be set at other suitable positions, as long as the coil is set to surround the substrate 201 when the anti-reflection coating is formed on the substrate 201.

[0044] In one embodiment, the distribution length L of the coil 302 is 180 mm-500 mm, and the diameter D of the coil 302 is 350 mm-800 mm. It should be noted that in some embodiments, when the anti-reflection coating is formed in the opening, the anti-reflection coating 205 formed can also be formed on the surface of the dielectric layer 202 .

[0045] In one embodiment, reference Figure 8 , Figure 8 exist Figure 6After forming the anti-reflective coating 205 in the opening (or through hole), the method further comprises: forming a patterned photoresist layer 207 on the dielectric layer 202, wherein the patterned photoresist layer 207 has a second opening 208 exposing the through hole and a portion of the dielectric layer around the through hole; Fig. 9 and Fig.10 Using the patterned photoresist layer 207 as a mask, a portion of the dielectric layer is etched away along the second opening 208 and the anti-reflective coating 205 is removed, so as to form a groove 209 in the dielectric layer 202 that is connected to the through hole 203 .

[0046] refer to Fig.11 , a conductive material is filled in the trenches and through holes to form a dual damascene structure 210 .

[0047] The conductive material is metal, and the metal includes copper.

[0048] In other embodiments, after forming an anti-reflective coating in the opening, the steps further include: removing the anti-reflective coating to re-expose the opening; and filling the opening with a conductive material to form a conductive connection structure.

[0049] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A method for forming a semiconductor structure, characterized in that: include: providing a substrate; forming a dielectric layer on the substrate; forming an opening in the dielectric layer; forming an anti-reflection coating in the opening, and applying an alternating current around the substrate when forming the anti-reflection coating; The anti-reflection coating is removed to expose the opening again; and a conductive material is filled in the opening to form a conductive connection structure.

2. The method for forming a semiconductor structure according to claim 1, wherein: The anti-reflection coating is formed in a coating chamber, wherein a suction cup for adsorbing a substrate is provided in the coating chamber, and a chamber wall is provided around the coating chamber, and a coil surrounding the suction cup is arranged on the side wall of the chamber wall.

3. The method for forming a semiconductor structure according to claim 2, wherein: When forming the anti-reflective coating, the substrate is placed on the suction cup, and the suction cup controls the rotation of the substrate. When the substrate rotates, the anti-reflective coating material is sprayed from above the substrate, and alternating current is applied to the coil at the same time, and the alternating current generates a magnetic field force perpendicular to the surface of the substrate in the coating chamber.

4. The method for forming a semiconductor structure according to claim 3, wherein: The voltage of the alternating current is 180-380V, and the frequency is 0.5-50Hz.

5. The method for forming a semiconductor structure according to claim 3 or 4, characterized in that: The number of turns of the coil is greater than 100, the diameter of the coil is greater than the diameter of the substrate on the suction cup, and the distribution length of the coil along the side wall is greater than the total thickness of the suction cup and the substrate on the suction cup.

6. The method for forming a semiconductor structure according to claim 5, wherein: The distribution length of the coil is 80mm-500mm, and the diameter of the coil is 350mm-800mm.

7. The method for forming a semiconductor structure according to claim 1, wherein: The opening is a through hole located in the dielectric layer; after forming an anti-reflection coating in the through hole, etching to remove a portion of the dielectric layer and the anti-reflection coating, forming a groove connected to the through hole in the dielectric layer; filling the groove and the through hole with a conductive material to form a dual damascene structure.

8. The method for forming a semiconductor structure according to claim 7, wherein: After the anti-reflective coating is formed in the through hole, the method further includes: forming a patterned photoresist layer on the dielectric layer, wherein the patterned photoresist layer has a second opening exposing the through hole and a portion of the dielectric layer around the through hole; using the patterned photoresist layer as a mask, etching away a portion of the dielectric layer and the anti-reflective coating along the second opening, and forming a groove in the dielectric layer that is connected to the through hole.

9. The method for forming a semiconductor structure according to claim 7, wherein: The substrate also has a connection metal pad, and the dual damascene structure is connected to the connection metal pad.

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