Pre-wetting method and device for wafer

Abstract

The present application provides a pre-wetting method and device for a wafer. The method comprises: vacuumizing a cavity to bring the vacuum degree in the cavity to a preset value, wherein there is a wafer in the cavity; vaporizing a liquid into vapor; and conveying the vapor to the surface of the wafer, and making the vapor enter pores in the wafer and condense on the surface of the wafer so as to form a liquid adsorption layer. The pre-wetting method and device for a wafer of the present application can remove a gas from pores in the wafer, thereby improving the pre-wetting effect in a vacuum environment; for a structure having a high aspect ratio, while the pre-wetting effect is ensured, the pre-wetting process time can be effectively reduced and the productivity can be increased; moreover, due to good pore-filling performance of vapor molecules, there is no need to perform a pre-wetting process in a high vacuum environment, thereby shortening the vacuumizing treatment time of the cavity, and further increasing the productivity; and in the vacuum environment, due to a small interaction force between molecules, the mean free path of molecules increases, and the vapor molecules can expand the effective contact area and improve the uniformity of the pre-wetting of the wafer.

Description

Wafer pre-wetting method and device TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing, in particular to a wafer pre-wetting method and device. BACKGROUND

[0002] With the continuous emergence of various new advanced packaging technologies, the integration density of electronic devices is becoming higher and higher, and three-dimensional stacked integrated circuits will become the preferred solution to surpass Moore's Law to improve chip performance.

[0003] TSV (Through Silicon Via) is a key technology for realizing interconnection of three-dimensional stacked integrated circuits. It can make vertical conduction between chips and provide shorter electrical connection paths to realize interconnection between chips.

[0004] Copper is widely used in TSV interconnection technology due to its good electrical conductivity and anti-electromigration performance. Electroplated copper has become the main process for TSV filling. Electroplating copper mainly involves three processes: pre-wetting treatment before electroplating, pre-wetting treatment of seed layer in deep hole, removing bubbles inside deep hole, improving wettability of electrolyte in deep hole, improving void or gap defects caused by insufficient electrolyte immersion in the hole during electroplating, and improving the reliability of the chip; then defect-free filling of deep hole by electrochemical plating; finally, cleaning and drying treatment of the electroplated wafer.

[0005] Currently, the pre-wetting treatment before electroplating generally adopts the following steps: first, the wafer is transferred into a pre-wetting cavity, then the cavity is vacuumed, and when the air pressure in the cavity reaches the set process pressure, deionized water is sprayed into the cavity to fill the deep hole with deionized water to achieve the pre-wetting effect.

[0006] The above-mentioned pre-wetting treatment before electroplating currently has the following problems: 1. If the wafer in the cavity needs to reach the process required vacuum degree, a long time of vacuuming is needed to reach a high vacuum degree; 2. Due to the deep hole, a long time of deionized water spraying is needed, which is similar to problem 1, and these will directly affect the production efficiency of the wafer; 3. For deep holes with large aspect ratio, the pre-wetting effect has a process bottleneck. SUMMARY

[0007] In order to solve the above problems, in a first aspect, the present application provides a wafer pre-wetting method, comprising:

[0008] vacuuming the cavity to make the vacuum degree in the cavity reach a preset value, wherein the cavity contains a wafer;

[0009] vaporizing the liquid into vapor;

[0010] The vapor is delivered to the wafer surface, so that the vapor enters the holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer.

[0011] According to a specific implementation of the embodiment of the present application, before the cavity is vacuumized, the method further includes: purging gas into the cavity.

[0012] According to a specific implementation of the embodiment of the present application, the preset value of the vacuum degree in the cavity is 10-100 torr.

[0013] According to a specific implementation of the embodiment of the present application, the holes are through silicon vias.

[0014] According to a specific implementation of the embodiment of the present application, during the process of delivering the vapor to the wafer surface, the wafer rotates at a preset rotation speed.

[0015] In a second aspect, the present application provides a device for wafer pre-wetting, comprising:

[0016] a cavity;

[0017] a vacuum processing device configured to make the vacuum degree in the cavity reach a preset value;

[0018] a wafer holding device arranged in the cavity and configured to hold the wafer;

[0019] a vapor generating device configured to convert liquid into vapor;

[0020] a vapor delivery device configured to deliver the vapor to the wafer surface, so that the vapor enters the holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer.

[0021] According to a specific implementation of the embodiment of the present application, the device further includes: a gas-liquid separation device arranged between the vacuum processing device and the cavity.

[0022] According to a specific implementation of the embodiment of the present application, the device further includes a purging device configured to deliver compressed gas into the cavity and swing according to the arrangement in the cavity.

[0023] According to a specific implementation of the embodiment of the present application, the preset value of the vacuum degree in the cavity is 10-100 torr.

[0024] The wafer pre-wetting method and device disclosed in the application can remove the gas in the hole of the wafer, thereby improving the pre-wetting effect in a vacuum environment; for high aspect ratio structures, the pre-wetting process time can be effectively reduced while ensuring the pre-wetting effect, thereby improving the production capacity; at the same time, due to the good hole filling performance of the vapor molecules, the pre-wetting process does not need to be performed in a high vacuum environment, thereby shortening the time of cavity vacuum treatment and further improving the production capacity; in a vacuum environment, due to the small intermolecular interaction force, the average free path of molecules increases, the vapor molecules can expand the effective contact area, and the uniformity of wafer pre-wetting is improved.

[0025] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the structure indicated in the specification and drawings.

[0026] SUMMARY

[0027] The features and performances of the present application are further described by the following examples and drawings.

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0029] Fig. 1 shows a wafer pre-wetting method flowchart according to an embodiment of the present application;

[0030] Fig. 2 shows a structure schematic diagram of a wafer pre-wetting device according to an embodiment of the present application;

[0031] Fig. 3 shows a wafer pre-wetting method flowchart according to an embodiment 1 of the present application; and

[0032] Fig. 4 shows a wafer pre-wetting method flowchart according to an embodiment 2 of the present application.

[0033] Preferred embodiments of the present application

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0035] The present application provides a method and apparatus for wafer pre-wetting. The pre-wetting process according to the embodiments provided herein can be implemented in an electroplating chamber or in a pre-wetting chamber within an apparatus comprising a pre-wetting chamber and an electroplating chamber.

[0036] Referring to FIG. 1, a flow chart of a wafer pre-wetting method according to an embodiment of the present application is shown. As shown in FIG. 1, the wafer pre-wetting method according to the present application comprises: step S1, vacuumizing the chamber to a pre-set value, wherein the chamber contains a wafer; step S2, vaporizing the liquid into vapor; and step S3, delivering the vapor to the wafer surface so that the vapor enters the holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer. It should be understood that the step numbers provided herein do not limit the process sequence in actual process. In actual process, each step can be implemented according to actual needs.

[0037] The main purpose of vacuumizing the chamber is to remove the gas in the chamber and the holes on the wafer so as to avoid the formation of bubbles in the holes on the wafer. To achieve this result, the wafer with holes is placed in the chamber, and the chamber is vacuumized by a vacuum treatment apparatus to a pre-set value, which is generally 10-100 torr in the present embodiment. It should be understood that at this time, the chamber contains the wafer, and the wafer has a hole structure, and the hole is a through silicon via with a high aspect ratio. Exemplarily, the vacuum treatment apparatus in the present embodiment can be, but is not limited to, a vacuum pump or other device capable of removing gas from the holes and the chamber. Further, before vacuumizing the chamber, a purging device is used to purge gas into the chamber to remove the residual pre-wetting liquid that forms the liquid adsorption layer.

[0038] The vapor is delivered to the wafer surface so that the vapor enters the holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer. Specifically, the liquid is first vaporized into vapor by a vapor generation apparatus, and then the vapor is delivered to the wafer surface by a vapor delivery apparatus, so that the vapor enters the holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer.

[0039] Specifically, the liquid can be heated to vaporize the liquid, or a carrier gas can be used to flush the heated liquid to complete the vaporization of the liquid. The vapor is transported by a vapor delivery device into the chamber and delivered to the wafer surface. The probability of collision between the vapor molecules and other gas molecules is small, the kinetic energy loss of the vapor molecules is small, and the free path of movement is increased, thereby ensuring that the vapor molecules are more likely to enter the holes on the wafer. Because the gas in the hole has been removed at this time, the higher temperature vapor molecules are more likely to condense in the hole, and then gradually condense into a liquid adsorption layer on the wafer surface. It should be understood that, in order to ensure that the vapor can be more uniformly distributed in each area of the wafer surface, the wafer can be rotated at a predetermined rotation speed during the delivery of the vapor to the wafer surface.

[0040] It should be understood that the holes on the wafer described in the present application include not only through holes in the actual sense, but also non-through holes; that is, the recessed structure on the wafer is included in the meaning of "hole" in the present application. Therefore, the wafer pre-wetting method of the present application is not only suitable for the pre-wetting process of a deep hole structure wafer with a high aspect ratio, but also suitable for the pre-wetting process of a wafer with a non-high aspect ratio hole structure.

[0041] The application also provides a wafer pre-wetting device used in cooperation with the method. Referring to FIG. 2, the wafer pre-wetting device 200 comprises a cavity 201, a vacuum treatment device 202, a wafer holding device 203, a vapor generating device 204, and a vapor delivery device 205. The cavity 201 contains a wafer 001, and the wafer 001 has a hole structure. The vacuum treatment device 202 is configured to make the vacuum degree in the cavity 201 reach a preset value. In the embodiment, the preset value of the vacuum degree in the cavity is generally 10-100 torr. In the embodiment, the vacuum treatment device can be, but is not limited to, a vacuum pump or other device capable of removing gas from the hole and the cavity 201. The wafer holding device 203 is arranged in the cavity 201 and is configured to hold the wafer 001 and rotate the wafer 001. In an embodiment, the wafer 001 can be rotated by driving the wafer holding device 203 with a motor. The vapor generating device 204 is configured to convert liquid into vapor. Specifically, the vapor generating device 204 can be a heater. After the vapor generating device 204 vaporizes the liquid, the vapor is delivered to the vicinity of the surface of the wafer 001 in the cavity 201 through a nozzle 2051 of the vapor delivery device 205 arranged in the cavity 201, enters the hole on the wafer, and condenses on the surface of the wafer to form a liquid adsorption layer, i.e., a pre-wetting layer. The application also provides a purging device 206 configured to deliver compressed gas and swing in the cavity 201 to purge the residual pre-wetting liquid in the cavity 201. The pre-wetting liquid is condensed from the vapor. The purging device 206 is configured to swing in the cavity 201 to purge the residual pre-wetting liquid to a liquid discharge port 208. At this time, a first valve 209 arranged near the liquid discharge port 208 is opened to discharge the pre-wetting liquid out of the cavity 201, ensure the dryness and cleanliness of the cavity 201, and prevent the normal progress of the next process. After the liquid is discharged, the first valve 209 is closed. The purging device 206 comprises a compressed gas delivery pipe 2061, a purging nozzle 2062, and a second driver 2063. The compressed gas delivery pipe 2061 is configured to deliver compressed gas to the purging nozzle 2062. The second driver 2063 is configured to drive the purging nozzle 2062 to swing in the cavity 201 to purge the residual pre-wetting liquid in the cavity. Further, the application also provides a gas-liquid separation device 207 arranged between the vacuum treatment device 202 and the cavity 201. The arrangement of the gas-liquid separation device 207 can avoid the water vapor remaining in the cavity 201 after the previous pre-wetting process and purging from entering the vacuum treatment device 202, which affects the service life of the vacuum treatment device 202. The arrangement of the gas-liquid separation device 207 between the vacuum treatment device 202 and the cavity 201 can collect the water vapor in the cavity 201 in the gas-liquid separation device 207 during the vacuumizing process, only let the gas pass through the vacuum treatment device 202, protect the vacuum treatment device 202, prolong the service life of the vacuum treatment device 202, and reduce the cost.Further, a second valve 210 is arranged between the gas-liquid separation device 207 and the cavity 201. When the vacuum processing device 202 is vacuumizing the cavity 201, the second valve 210 is opened; after the vacuumizing is completed, the second valve 210 is closed to prevent the vapor from entering the gas-liquid separation device 207 during the process of delivering the vapor into the cavity 201.

[0042] The wafer pre-wetting method and device provided by the present application can remove the gas in the holes on the wafer, thereby improving the pre-wetting effect in a vacuum environment; for high aspect ratio structures, the pre-wetting process time can be effectively reduced while ensuring the pre-wetting effect, thereby improving the production capacity; at the same time, due to the good hole filling performance of the vapor molecules, the pre-wetting process does not need to be performed in a high vacuum environment, thereby shortening the time of vacuum processing of the cavity and further improving the production capacity; in a vacuum environment, due to the small intermolecular interaction force and the increased mean free path of molecules, the vapor molecules can expand the effective contact area, thereby improving the uniformity of wafer pre-wetting.

[0043] Embodiment 1

[0044] The present embodiment provides a wafer pre-wetting method, which will be described with reference to FIG. 3. FIG. 3 shows a flowchart of the wafer pre-wetting method in the present embodiment 1. As shown in FIG. 3, the method comprises the following steps:

[0045] Step S101: using a purge device to purge gas into the cavity.

[0046] Step S102: vacuumizing the cavity to make the vacuum degree in the cavity reach a preset value, and the cavity contains a wafer.

[0047] For example, the vacuum degree preset value in the present embodiment can be selected as 100 torr. The filling effect of the vapor is better than that of the liquid pre-wetting liquid, so compared with ordinary liquid water, the required vacuum for pre-wetting is also relatively low. For example, ordinary liquid water pre-wetting can be performed only under a vacuum condition of 25 torr, while vapor pre-wetting can meet the process requirements under a condition of 75 torr, thereby reducing the vacuum processing time, improving the process efficiency, and improving the production capacity.

[0048] Step S103: vaporizing the liquid to form vapor.

[0049] In the present embodiment, the liquid vaporization is performed by heating the liquid to a preset temperature. For example, when the pre-wetting liquid is deionized water, the preset temperature is 100°C.

[0050] Step S104: delivering the vapor to the wafer surface, so that the vapor enters the holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer.

[0051] It is worth noting that in this step, the wafer can be rotated at a preset speed or left stationary while the vapor delivery equipment moves relative to the wafer.

[0052] The wafer pre-wetting method described in this application employs a vacuum treatment followed by vapor pre-wetting. High-temperature vapor in a vacuum environment significantly enhances the pre-wetting effect on pore structures. For high aspect ratio structures, it effectively reduces pre-wetting process time and increases throughput while ensuring pre-wetting effectiveness. Furthermore, due to the excellent pore-filling properties of vapor molecules, pre-wetting in a high-vacuum environment is unnecessary, shortening the cavity vacuum treatment time and further increasing throughput. In a vacuum environment, the intermolecular forces are weak, increasing the mean free path of molecules, allowing high-temperature vapor to expand the effective contact area and improve the uniformity of wafer pre-wetting.

[0053] Example 2

[0054] This embodiment provides a wafer pre-wetting method. Please refer to Figure 4, which shows a flowchart of the wafer pre-wetting method in Embodiment 2 of this application. As shown in Figure 4, the method includes:

[0055] Step S201: Use a purging device to purge gas into the cavity.

[0056] Step S202: Vaporize the liquid into steam.

[0057] In this embodiment, the liquid vaporization method involves injecting a carrier gas into the high-temperature liquid to vaporize it. Examples of carrier gases include air, nitrogen, helium, and argon.

[0058] Step S203: The vapor is delivered to the wafer surface, allowing it to enter the holes on the wafer and condense on the wafer surface to form a liquid adsorption layer.

[0059] It is worth noting that in this step, the wafer can be rotated at a preset speed or left stationary while the vapor delivery equipment moves relative to the wafer.

[0060] Step S204: Evacuate the cavity to achieve a preset vacuum level.

[0061] For example, the preset vacuum level in this embodiment can be selected as 100 torr. Furthermore, after completing this step, preferably, the wafer is left to stand for a period of time, for example, 20-60 seconds. Vacuum treatment creates a vacuum environment in the cavity, at which point a negative pressure environment is first formed on the surface of the liquid adsorption layer; then, during the 20-60 seconds the wafer is left to stand in the vacuum environment, under the action of the pressure difference, the air at the bottom of the hole breaks through the liquid adsorption layer in the form of bubbles, while condensed liquid enters the bottom of the hole to complete sufficient pre-wetting.

[0062] By the wafer pre-wetting method of the embodiments of the present application, a method of pre-wetting by steam and then vacuum treatment is adopted. By using the pressure difference between the vacuum environment and the gas in the hole, the high aspect ratio structure product is fully pre-wetted, preventing defects such as gaps or cavities in the electroplating process, and improving the uniformity of wafer pre-wetting.

[0063] Although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A wafer pre-wetting method, characterized by, The method comprises the following steps: vacuumizing the cavity to reach a preset vacuum degree, wherein the cavity contains a wafer; vaporizing a liquid into a vapor; delivering the vapor to the wafer surface, so that the vapor enters into holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer.

2. The wafer pre-wetting method of claim 1, wherein, before vacuumizing the cavity, the method further comprises: blowing a gas into the cavity.

3. The wafer pre-wetting method of claim 1, wherein, The preset vacuum degree in the cavity is 10-100 torr.

4. The wafer pre-wetting method of claim 1, wherein, The holes are through silicon vias.

5. The wafer pre-wetting method of claim 1, wherein During the process of delivering the vapor to the wafer surface, the wafer rotates at a preset rotating speed.

6. An apparatus for wafer pre-wetting, comprising: The method comprises the following steps: a cavity; a vacuum processing device configured to reach a preset vacuum degree in the cavity; a wafer holding device arranged in the cavity and configured to hold a wafer; a vapor generating device configured to convert a liquid into a vapor; a vapor delivering device configured to deliver the vapor to the wafer surface, so that the vapor enters into holes on the wafer and condenses on the wafer surface to form a liquid adsorption layer.

7. The apparatus for wafer pre-wetting of claim 6, wherein, The method further comprises: a gas-liquid separation device arranged between the vacuum processing device and the cavity.

8. The apparatus for wafer pre-wetting of claim 6, wherein, The method further comprises a blowing device configured to deliver a compressed gas into the cavity and swing in the cavity according to a preset mode.

9. The apparatus for wafer pre-wetting of claim 6, wherein, The preset vacuum degree in the cavity is 10-100 torr.

Images