TWI527143B - Drying method of chip stacked structure and system thereof - Google Patents

Description

Drying method of wafer stack structure and system thereof

The present invention relates to a drying technique after wafer cleaning, and more particularly to a method and system for drying a three-dimensional, vertically interconnected wafer stack structure.

Press, the microprocessor chip generally includes a logic unit and a plurality of cache memories. If both are configured in a two-dimensional (2-D) pattern, the physical size of the wafer is limited to the number of cache memories. (caused by poor process of large-area wafers), which strictly limits the performance of the microprocessor.

In order to solve the problem of 2-D resources on a wafer, a method of establishing a three-dimensional (3-D) integrated circuit is being actively developed. For example, a typical 3-D IC process includes: Via Formation, Via Filling, Wafer Thinning, and Wafer Bonding. Four major steps. However, the gap between wafer and wafer or wafer and wafer bonding is usually less than 20~30 μm, so how to clean and dry the flux or other impurities in such tiny gaps is urgently needed to overcome the challenge. The technical bottleneck.

Wafer cleaning and drying steps must be performed before and after each semiconductor process to avoid contamination of the wafer during processing. In the semiconductor process, wafer contamination is caused by particle contamination and membrane fouling. The membrane fouling is mainly caused by foreign matter on the wafer, such as acetone, trichloroethylene, isopropanol, methanol, and dimethyl. A residual organic solvent such as benzene or a photoresist developer, an oil film, and a metal film. However, the currently used drying process uses nitrogen to dry the wafer, but the current development trend is to make a delicate three-dimensional pattern on a large-sized wafer, so that the wafer is not completely dried or can not be dried after the cleaning step. Therefore, it has a considerable adverse effect on the subsequent process, which in turn greatly reduces the yield and even causes the wafer to be scrapped.

Therefore, the inventors of the present invention have in fact improved the necessity of the conventional wafer drying technology, and have actively researched and improved the wafer drying method and the drying device with years of experience in creative design and professional manufacturing in related fields. The "drying method of the wafer stack structure" of the present invention was finally developed under the careful consideration of various conditions.

The present invention is directed to the absence of the prior art, and its main object is to provide a method for drying a wafer stack structure and a system thereof, which are capable of effectively drying wafers, particularly in a wafer stack structure for drying three-dimensional, vertical interconnections. A small gap, which can improve the subsequent process yield.

To achieve the above object, the present invention adopts the following technical solution: a method for drying a wafer stack structure, comprising the steps of: firstly, providing a wafer stack structure after deionized water cleaning; and then moving the wafer stack structure into loading a storage tank of an organic solvent; then, the deionized water remaining on the wafer stack structure is replaced with the organic solvent; finally, the wafer stack structure is moved into a vacuum drying chamber and placed in a vacuum environment for a predetermined time .

The invention further provides a drying system for a wafer stack structure, comprising a wafer rinsing device, a wafer cleaning device, an organic solvent storage tank, a high frequency ultrasonic oscillating device and a vacuum drying chamber.

Wherein the wafer rinsing apparatus comprises at least one gas nozzle for performing high pressure jet on a wafer stack structure to remove residual flux on the wafer stack structure; the wafer rinsing apparatus is connected to the wafer rinsing apparatus and Included at least one liquid nozzle for uniformly spraying high temperature deionized water onto the surface of the wafer stack structure; An organic solvent storage tank is connected to the wafer cleaning device for accommodating the deionized water-cleaned wafer stack structure; the high-frequency ultrasonic oscillating device is disposed under the organic solvent storage tank for the organic solvent The storage tank performs an oscillating action to replace the residual deionized water on the wafer stack structure with the organic solvent; the vacuum drying chamber is connected to the organic solvent storage tank for volatilizing the residual organic solvent on the wafer stack structure And bring it out.

Compared with the prior art, the present invention has obvious advantages and beneficial effects: the drying method of the wafer stack structure of the present invention, the step of dissolving deionized water through an organic solvent and the step of drying in a vacuum environment, in addition to greatly improving the overall process rate, Since the organic solvent storage tank does not need to be heated, it is also possible to prevent the organic solvent storage tank from exploding because the instantaneous temperature is too high and the instantaneous concentration of the organic solvent vapor is too large.

Other objects and advantages of the present invention will be further understood from the technical features disclosed herein. The above and other objects, features, and advantages of the present invention will be apparent from

W‧‧‧ wafer stack structure

C‧‧‧ wafer

S‧‧‧Substrate

G‧‧‧Small gap

10‧‧‧ Wafer rinsing equipment

11‧‧‧ gas nozzle

20‧‧‧ Wafer Cleaning Equipment

21‧‧‧Liquid dispensing

30‧‧‧Organic solvent storage tank

31‧‧‧Organic solvents

40‧‧‧vacuum drying room

50‧‧‧Ultrasonic device

60‧‧‧water bath

S12~S18‧‧‧ Process steps

1 is a cross-sectional view showing a wafer stack structure of the present invention.

2 is a flow chart showing a method of drying a wafer stack structure according to a first embodiment of the present invention.

Figure 3 is a block diagram of a drying system of a wafer stack structure in accordance with a first embodiment of the present invention.

4 is a schematic view showing the process of the deionized water removal step of the first embodiment of the present invention.

Figure 5 is a schematic view showing the process of the deionized water removal step of the second embodiment of the present invention.

Referring to FIG. 1, the disclosure mainly provides a method for drying a wafer stack structure and a system thereof, which are suitable for drying a three-dimensional (3-D), vertically interconnected wafer stack structure W, the wafer stack The structure W usually has a plurality of micro gaps between the wafer C and the substrate S. The drying method and system of the present disclosure are organic for remaining in the minute gaps G (about 20 to 30 μm ). The solvent also exerts an excellent drying effect.

[First Embodiment]

Please refer to FIG. 2, which is a schematic flow chart of a method for drying a wafer stack structure according to a first embodiment of the present invention. The method of this embodiment includes at least a flux removal step S12, a high temperature deionized water cleaning step S14, a deionized water removal step S16, and a vacuum drying step S18. Hereinafter, the specific contents of each step will be described in detail with reference to the schematic diagram of the drying system of the stacked structure shown in FIG. 3. Those skilled in the art can easily understand the advantages and effects of the present invention by the contents of the disclosure, and do not deviate from the present invention. Various modifications and changes are made in the spirit of the invention to practice or apply the method of the invention.

First, step S12 is performed to carry out a flux remaining in the wafer stack structure W with water or a vapor of a solvent. In this embodiment, the wafer stack structure W is first moved from a carrier device (not shown) to a wafer rinsing device 10 by a robot arm, and then the bonding position of the wafer C and the substrate S is performed by using the gas nozzle 11. The high pressure jet dissolves the flux with steam and carries out a small gap G between the wafer C and the substrate S; it is worth noting that the vapor molecule is a small molecule that can easily pass through the minute gap G to facilitate carry-over Residual flux. However, the above is only one possible implementation manner of the present invention, and the present invention is not limited thereto.

Next, step S14 is performed to uniformly spray high temperature deionized water (hot DI water) onto the above wafer stack structure W. In this embodiment, the wafer stack structure W is moved from the carrier device to a wafer cleaning device 20 by a robot arm, and then the high temperature deionized water is directly sprayed onto the surface of the wafer stack structure W by the liquid nozzle 21 so that It removes particles and removes organic matter and metal contaminants. Similarly, the above is only one possible implementation manner of the present invention, and the present invention is not limited thereto.

Thereafter, step S16 is performed to perform an oscillation process for replacing the deionized water remaining on the wafer stack structure W with an organic solvent. As shown in FIG. 4, specifically, the wafer stack structure W is transported to an organic via a transport trolley (not shown). Above the solvent storage tank 30, and using a power device (not shown) to operate the carrier to descend into the organic solvent storage tank 30, so that the wafer stack structure W is immersed in the organic solvent 31; then the present invention further applies to the organic solvent storage tank 30 Give a shock action.

In this embodiment, the oscillating action is ultrasonic shock applied by the ultrasonic device 40 placed at the bottom of the organic solvent storage tank 30, and preferably is a high frequency ultrasonic oscillating (>20 MHz), and the oscillating time is about Between 1 and 30 minutes, the residual W-depleted water on the wafer stack can be completely replaced.

It should be noted that the organic solvent 31 used in the present embodiment must be miscible with water; in a preferred embodiment of the invention, the organic solvent is selected from the group consisting of methanol, ethanol, isopropanol (IPA) or acetone ( Acetone), in which acetone is the best. The principle is that the saturated vapor pressure of acetone is 174 mmHg (20 ° C), the saturated vapor pressure of methanol is 160 mmHg (30 ° C), the saturated vapor pressure of ethanol is 44.3 mmHg (30 ° C), and the saturated vapor pressure of isopropanol is 33mmHg (28 ° C), which is helpful for the subsequent drying step; and according to the experimental results, the acetone can completely remove the deionized water within 5 minutes of shaking.

In addition, in addition to improving the overall process rate, this step does not require heating operation of the organic solvent storage tank 30, so that the organic solvent storage tank 30 can be prevented from being excessively generated due to an excessive temperature of the organic solvent vapor. explosion.

Finally, step S18 is performed to move the wafer stack structure W into a vacuum drying chamber 50 and place it in a vacuum environment for a predetermined time. Specifically, the wafer stack structure W is moved from the carrier device to a vacuum drying chamber 50 by a robot arm, and then left for 1 to 5 minutes to completely evaporate the residual organic solvent to complete the drying process of the embodiment; In the preferred embodiment of the invention, the vacuum environment means that the vacuum drying chamber 50 is evacuated to a vacuum of -80 kPa or more to control the ambient air pressure to be below 160 mmHg, whereby the acetone is only required to be placed at a normal temperature. It can be directly boiled in 2 minutes, which further increases the overall process rate. However, the above is only For a preferred embodiment of the present invention, the present invention is not limited thereto.

[Second embodiment]

Please refer to FIG. 5 , which is a schematic diagram of a process for removing a deionized water according to a second embodiment of the present invention, and please refer to FIG. 2 . The main difference between this embodiment and the previous embodiment is that the deionized water removal step S16 of the present embodiment adopts a water-sense oscillating manner.

Specifically, the organic solvent storage tank 30 is subjected to high-frequency ultrasonic vibration in a water bath environment; in other words, in this embodiment, the organic solvent storage tank 30 is first placed in a water bath 60, and then the ultrasonic bath 40 is used for the water bath. 60 performs high-frequency ultrasonic oscillation, and controls the displacement of the organic solvent 31 and the deionized water on the wafer stack structure W by the degree of oscillation of the water wave. It is further worthy to note that this method can also prevent the organic solvent storage tank 30 from exploding due to an excessive temperature.

Referring to FIG. 3, in order to complete all the steps in the drying method of the above wafer stack structure, the present invention further provides a wafer stack structure drying system including a wafer rinsing apparatus 10, a wafer cleaning apparatus 20, and a The organic solvent storage tank 30, a high frequency ultrasonic oscillating device 40 and a vacuum drying chamber 50.

The wafer rinsing apparatus 10 includes at least one gas nozzle 11 for performing high pressure jet on a wafer stack structure W to remove residual flux on the wafer stack structure W; the wafer cleaning apparatus 20 is connected to the wafer rinsing apparatus. 10 and comprising at least one liquid nozzle 21 for uniformly spraying high-temperature deionized water onto the surface of the wafer stack structure W; the organic solvent storage tank 30 is connected to the wafer cleaning device 20 for accommodating the deionized water after cleaning The high-frequency ultrasonic oscillating device 40 is disposed under the organic solvent storage tank 30 for performing an oscillating action on the organic solvent storage tank 30 to replace the residual deionized water on the wafer stack structure W into the organic The solvent drying chamber 50 is connected to the organic solvent storage tank 30 for volatilizing and carrying out the organic solvent remaining on the wafer stack structure W.

In the preferred embodiment of the present invention, the drying system further includes a water bath 60. The organic solvent storage tank 30 is partially housed in the water bath 60, and the high frequency ultrasonic oscillating device 40 is fixed to the bottom of the water bath 60.

In summary, the present invention has at least the following advantages over conventional drying methods and apparatus:

1. The drying method of the wafer stack structure of the present invention can effectively dry the wafer, and is particularly suitable for the organic solvent remaining in the minute gap between the wafer and the substrate, thereby ensuring the quality of the integrated circuit components on the wafer.

2. The drying method of the wafer stack structure of the present invention, the step of dissolving the deionized water by the organic solvent and the step of drying in the vacuum environment, in addition to greatly improving the overall process rate, since the organic solvent storage tank is not required to be heated, It is also possible to prevent the organic solvent storage tank from exploding due to an excessive instantaneous temperature of the organic solvent vapor due to an excessively high temperature.

3. The drying method of the wafer stack structure of the present invention can surely reduce defects on the wafer, thereby increasing the time interval for cleaning and maintenance of the processing machine, thereby increasing the throughput of the processing machine.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Therefore, the equivalents of the present invention and the equivalents of the drawings are all included in the present invention. Within the scope of protection, it is given to Chen Ming.

10‧‧‧ Wafer rinsing equipment

11‧‧‧ gas nozzle

20‧‧‧ Wafer Cleaning Equipment

21‧‧‧Liquid dispensing

30‧‧‧Organic solvent storage tank

40‧‧‧Ultrasonic device

50‧‧‧vacuum drying room

Claims (7)

A method for drying a wafer stack structure, comprising the steps of: high-pressure jetting a wafer stack structure using a gas nozzle, carrying out flux remaining on the wafer stack structure with water or solvent vapor; cleaning with deionized water The wafer stack structure; the wafer stack structure is moved into a storage tank loaded with an organic solvent; and the storage tank loaded with the organic solvent is subjected to an oscillating action by using a high frequency ultrasonic oscillating device having a frequency greater than 20 MHz to stack the wafer The structurally residual deionized water is replaced with the organic solvent; and the wafer stack structure is moved into a vacuum drying chamber and placed in a vacuum environment for a predetermined period of time. The method of drying a wafer stack structure according to claim 1, wherein the wafer stack structure has a minute gap between a wafer and a substrate, and the vapor or water vapor remains in the flux removing step. The flux in the minute gap dissolves and is carried out. The method of drying a wafer stack structure according to claim 1, wherein the organic solvent is methanol, ethanol, isopropanol or acetone. The method of drying a wafer stack structure according to claim 1, wherein the time of the oscillating process is between 1 and 30 minutes. The method of drying a wafer stack structure according to claim 1, wherein the predetermined time is between 1 and 5 minutes. A wafer stacking structure drying system comprising: a wafer rinsing apparatus comprising at least one gas nozzle for performing high pressure jet on a wafer stack structure to remove residual flux on the wafer stack structure; a cleaning device coupled to the wafer processing apparatus and including at least one liquid nozzle for uniformly spraying deionized water onto the surface of the wafer stack structure; An organic solvent storage tank is connected to the wafer cleaning device for accommodating the wafer stack structure after the deionized water cleaning; a high frequency ultrasonic oscillating device with a frequency greater than 20 MHz is disposed in the organic solvent storage tank a buffering action for the organic solvent storage tank to replace the residual deionized water on the wafer stack structure with the organic solvent; and a vacuum drying chamber connected to the organic solvent storage tank The organic solvent remaining on the wafer stack structure is volatilized and taken out. The drying system of the wafer stack structure of claim 6, further comprising a water bath, wherein the organic solvent storage tank is partially housed in the water bath, and the high frequency ultrasonic oscillating device is connected to the water bath.