TWI487013B - Semiconductor cleaning method and apparatus and controlling method of the same - Google Patents

Description

Semiconductor cleaning method and device and control method thereof

The present invention relates to a cleaning method, and more particularly to a semiconductor cleaning method and apparatus and a control method therefor.

The fabrication of semiconductor devices, such as wafers, utilizes a variety of development techniques, including, in particular, photolithographic processes, which have become standard processes for forming and patterning different layers of materials in a semiconductor process. The operation procedure of the general photolithography process comprises: depositing a photoresist layer on the semiconductor device; exposing the selected portion of the photoresist layer; and dissolving the unnecessary photoresist by the developer to develop the photoresist layer, wherein When a positive photoresist is used, the portion irradiated with light is dissolved in the developer, whereas if a negative photoresist is used, the portion where the light is not irradiated is dissolved in the developer. Thereafter, the semiconductor device is further cleaned to completely remove the developer. After cleaning, the semiconductor device is typically blown dry with a gas such as nitrogen to remove excess liquid and impurities. Next, before the photolithography process is completed, the step of hard baking the photoresist layer is performed to strengthen the structure of the photoresist layer.

Due to the market competition, the quality requirements of semiconductor devices are getting higher and higher. Due to the performance of semiconductors and the fine structure of semiconductors, various semiconductor manufacturers are working to improve the structure of semiconductor devices. However, limited by the limitations of conventional semiconductor processes, particularly the photolithography process mentioned above, process yields are not always satisfactory. For example, after the development step of the semiconductor device, the photoresist layer is usually accompanied by a plurality of defects, which are mostly composed of a collapsed photoresist structure, which not only reduces the quality of the semiconductor device but also affects the process yield. How to solve the above problems is a necessary issue.

The invention relates to a semiconductor cleaning method and device and a control method thereof for effectively maintaining the structure of a photoresist layer in a semiconductor process, thereby reducing the incidence of defects and increasing the process yield.

According to an aspect of the present invention, a semiconductor cleaning method is provided, which comprises the steps of: providing a developer to a pre-exposed photoresist layer of a wafer; and spraying the nozzle at a position above the center of the wafer for a period of time. a liquid to photoresist layer, wherein the cleaning liquid does not react with the photoresist layer and the developer; moving the nozzle along the radial direction of the wafer to at least one position above the wafer; and stopping the nozzle at the at least one position The cleaning liquid is sprayed to the photoresist layer for at least another period of time; and the wafer is cleaned until the developer and the photoresist dissolved in the developer are washed away to expose one of the patterned photoresists of the wafer.

According to another aspect of the present invention, a semiconductor cleaning apparatus is provided that includes a carrier, a developer supply element, a rotary drive component, a cleaning fluid supply component, a motion drive component, and a controller. The carrier is used to carry a wafer, wherein the wafer has a pre-exposed photoresist layer. The developer supply element is used to supply a developer onto the wafer. The rotary drive element rotates the carrier and the wafer on the carrier, thereby uniformly dispersing the developer on the photoresist layer. The cleaning liquid supply member has a nozzle for spraying a cleaning liquid, wherein the cleaning liquid does not react with the photoresist layer and the developing solution. The motion driving element is used to move the nozzle. The controller is configured to control the cleaning liquid supply component and the motion driving component, wherein after the unnecessary photoresist is dissolved in the developer, the controller controls the nozzle to stay at a plurality of positions on the wafer, and the same or different length of time Spray the cleaning solution.

According to still another aspect of the present invention, a method of controlling semiconductor cleaning is provided, comprising the steps of: setting a path for nozzle movement, wherein a nozzle is used to spray cleaning liquid onto a wafer, and the path includes a plurality of positions where the nozzle stays Setting a plurality of lengths of time that the nozzle stays at the positions; and moving the nozzles according to the path and staying at the positions according to the length of time.

In order to make the above-mentioned contents of the present invention more comprehensible, the preferred embodiments are described below, and the detailed description is as follows:

The photolithography process for semiconductor fabrication generally includes the steps of coating a photoresist material, exposing the photoresist material, and developing a pattern of the photoresist material. This embodiment is described by taking the development of the photoresist and the cleaning process as an example, but the present invention is not limited thereto.

Please refer to FIG. 1 , which is a schematic diagram of a semiconductor cleaning apparatus 100 in accordance with a preferred embodiment of the present invention. The semiconductor cleaning apparatus 100 includes a carrier 101, a developer supply member 103, a rotary driving member 105, a cleaning liquid supply member 107, motion driving members 109, 110, and a controller 111. The carrier 101 is used to carry a wafer 200. The carrier 101 is, for example, a disk to provide sufficient suction to hold the wafer 200. The wafer 200 has a photoresist layer 201 that has been selectively exposed in advance to form a specific photoresist pattern that remains on the wafer 200 after the wafer 200 is developed.

The developer supply member 103 is used to supply a developer onto the wafer 200. The developer supply member 103 has a nozzle 112 that is controlled by the action driving member 110 to spray the developer onto the wafer 200 to dissolve the unnecessary photoresist 201A on the photoresist layer 201. The photoresist material is divided into a positive photoresist and a negative photoresist, and the developer can be selected according to the characteristics of the photoresist. For example, when the material of the photoresist layer 201 is a positive photoresist, the developer may be an alkaline solution, or preferably a dilute nonionic alkaline solution.

The rotary drive element 105 is coupled to the carrier 101 for rotating the carrier 101 and the wafer 200 on the carrier 101, thereby uniformly dispersing the developer or other type of solution on the photoresist layer 201. For example, the rotary drive element 105 includes a motor with a rotating shaft coupled to the carrier 101. The cleaning liquid supply element 107 has a nozzle 113 for spraying the cleaning liquid to the wafer 200, wherein the cleaning liquid does not react with the photoresist layer 201 and the developing solution to wash the wafer 200 and retain the photoresist pattern of the wafer 200. . The cleaning liquid is preferably pure water or ultrapure water.

The motion driving element 109 is used to move the nozzle 113 to change the position of the nozzle 113 relative to the wafer 200. Preferably, the motion driving component 109 and the motion driving component 110 of the control nozzle 112 each include a mechanical component such as a motor, a guide rail, a belt, a pulley, a gear set, and the like (not shown). In the present embodiment, the motion driving elements 109, 110 respectively drive the nozzles 113, 112 to move in the radial direction of the wafer 200.

The controller 111 is, for example, a programmable controller electrically connected to the developer supply member 103, the rotary drive member 105, the cleaning liquid supply member 107, and the action driving members 109, 110 to control the state of these components. For example, a specific program written by a computer code can be set in the controller 111 corresponding to the operation mode of the components, such that the moving paths of the nozzles 112, 113, the developer supply amount of the developer supply member 103, and the cleaning liquid supply member can be set. The cleaning liquid supply amount of 107 can be set in the controller 111 in advance before the development step of the wafer 200 is started. In addition, the order in which these components are actuated can also be planned and set in the controller 111 in advance.

Please refer to FIG. 2A, which is a flow chart of a method for controlling semiconductor cleaning according to a preferred embodiment of the present invention. The semiconductor cleaning control method includes steps S101 to S103. In step S101, a path of nozzle movement is first set, wherein the nozzle is used to spray the cleaning liquid onto the wafer, and the path includes a plurality of positions where the nozzle stays. As shown in Fig. 1, the path in which the nozzle 113 moves is preset in the controller 111. Next, as shown in step S102, a plurality of time periods in which the nozzle stays at these positions are set, and the length of time may be set in the controller 111. Then, as shown in step S103, the nozzles are moved in accordance with the path, and stay at the positions according to the length of time.

Please refer to FIG. 2B, which is a flow chart of a semiconductor cleaning method in accordance with a preferred embodiment of the present invention. The semiconductor cleaning method includes steps S201 to S208, and the respective steps will be described in detail later. During development, the nozzles stay at multiple locations above the wafer, and the length of time that each location can remain the same or different. Hereinafter, the description will be made by taking the nozzles at three positions above the wafer as an example, but the present invention is not limited thereto.

In step S201, a developer is supplied onto the wafer, wherein the wafer has a pre-exposed photoresist layer. Generally, in order to form a photoresist layer having a specific pattern, an opaque or translucent mask having a predetermined pattern may be overlaid on the coated photoresist layer, followed by exposure. Since the photoresist material has a photosensitive property, the photoresist portion not covered by the mask absorbs the light energy to change its reaction with the developer. Taking a positive resist as an example, after the positive photoresist is exposed for a period of time, the irradiated portion can be dissolved in the developing solution, and the unilluminated portion is not dissolved by the developing solution, so after the developing step, The photoresist pattern of the reticle with a predetermined pattern can be retained.

As shown in FIG. 1, before the nozzle 112 is sprayed with the developer, it is preferable to move the nozzle 112 to a position above the center of the wafer 200 to drip the developer directly to the center of the wafer 200.

Next, as shown in step S202, the wafer is rotated to uniformly spread the developer on the photoresist layer to dissolve the unnecessary photoresist. As shown in FIG. 1, when the rotary driving element 105 rotates the carrier 101 and the wafer 200, the centrifugal force generated by the rotation causes a pulling force to the developer, and the developer flows from the center of the wafer 200 to the wafer 200. edge. Under the action of the rotation of the carrier 101, the developer is dispersed on the photoresist layer 201 to uniformly dissolve the unnecessary photoresist, such as the exposed photoresist portion. After supplying sufficient developer, the motion drive component 110 then moves the nozzle 112 positioned above the center of the wafer 200 back to its original position, such as beyond the edge of the wafer 200. Thereafter, after the unnecessary photoresist is completely dissolved in the developer, the cleaning step of the wafer 200 can be performed.

As shown in step S203, the nozzle is left in the first position for a first time to spray the cleaning liquid onto the photoresist layer of the wafer, wherein the first position corresponds to a position above the center of the wafer. Please refer to FIG. 3A, which is a schematic diagram of a movable nozzle resting on different positions on the wafer. Preferably, the nozzle 113 of the cleaning liquid supply member 107 starts from a first position P1 at a position above the center of the wafer 200. The nozzle 113 stays in the first position P1 for a certain period of time, wherein the length of the first period of time can be preset in the controller 111, for example, 20 seconds.

During the first period of time, the stationary nozzle 113 sprays the cleaning liquid onto the wafer 200. At the same time, the rotary driving element 105 continuously rotates the carrier 101 and the wafer 200 thereon, and the generated centrifugal force acts on the cleaning liquid to draw the cleaning liquid in the direction of the edge of the wafer 200. When the cleaning liquid flows on the wafer 200, the developing solution and the dissolved photoresist are mixed with the cleaning liquid, and are gradually taken away by the centrifugal force. After the end of the first period of time, the cleaning method jumps to the next step S204.

In step S204, the nozzle is moved along the radial direction of the wafer to a second position above the wafer. As shown in FIG. 3A, the nozzle 113 can move on the wafer 200 at a constant speed or at a non-equal speed. Preferably, the nozzle 113 moves at a constant speed. While the nozzle 113 is moving to the second position P2, the nozzle 113 can continue or suspend the spraying of the cleaning liquid, which can be set in the controller 111 in advance according to actual needs. In the present embodiment, the moving nozzle 113 continuously sprays the cleaning liquid onto the wafer 200. When the second position P2 is reached, the nozzle 113 stays at the second position P2, and the cleaning method jumps to the next step S205.

In step S205, the nozzle is left in the second position for a second period of time to spray the cleaning liquid onto the photoresist layer of the wafer. This step is the same as step S203, but the length of the second period of time does not have to be the same as the first period of time, wherein the length of the second period of time can also be preset in the controller 111. In the present embodiment, the nozzles 113 preferably stay at the same position for the same time, i.e., the nozzle 113 stays at the second position P2 for about 20 seconds. After the end of the second period of time, the cleaning method jumps to the next step S206.

In step S206, the nozzle is moved along the radial direction of the wafer to a third position above the wafer. Thereafter, as shown in step S207, the nozzle is left in the third position for a third period of time to spray the cleaning liquid onto the photoresist layer. The length of the third period is the same as the first and second periods, which is about 20 seconds. In this embodiment, although the second position P2 is between the first position P1 and the third position P3, the nozzle 113 is moved along the path from the first position P1 to the third position P3, but the present invention does not Limited to this, the nozzle 113 can also move along a path other than P1-P3. The interval between the first position P1, the second position P2, and the third position P3 may be preset in the controller 111. Preferably, the interval between the first position P1 and the second position P2 is equal to the interval between the second position P2 and the third position P3, but is not limited thereto.

As shown in step S208, the wafer is cleaned until the developer and the photoresist dissolved in the developer are washed to expose one of the patterned photoresists of the wafer. The path from the first position P1 to the third position P3 may be repeated multiple times to completely clean the wafer 200. For example, as indicated by an arrow A1 in FIG. 3A, the nozzle 113 originally staying at the third position P3 is again moved back to the first position P1 to repeat the paths P1-P3. After the nozzle 113 is repositioned at the first position P1, the above steps S203 to S207 are repeated. The number of repetitions of the paths P1-P3 can be preset in the controller 111 according to the demand for the wafer 200. In other words, the movement trajectory of the nozzle 113 can be programmed by computer code and preset in the controller 111, so that the motion driving element 109 drives the nozzle 113 to move according to the set program. When the paths P1 - P3 in which the nozzles 113 move are repeated, the time at which the nozzles 113 stay at the respective positions can be reduced. For example, when the paths P1-P3 are repeated 2 or 3 times, the time of staying at the first position P1, the second position P2, and the third position P3 may each be 5 seconds.

Since the wafer 200 is continuously rotated when the cleaning liquid is sprayed onto the wafer 200 by the nozzle 113, the centrifugal force generated continuously flows out of the cleaning liquid, so that the developing solution and the dissolved photoresist are carried by the cleaning liquid. Walk instead of remaining on wafer 200. In addition, since the nozzle 113 is sprayed at different positions (such as the positions P1, P2, P3) during the cleaning process, the cleaning liquid is not sprayed on a specific position of the wafer 200 (such as the central position of the wafer 200). Therefore, the impact on the photoresist layer 201 of the wafer 200 is reduced. Furthermore, the efficiency with which the nozzle 113 sprays the cleaning liquid and its moving speed can be controlled by the controller 111. For the above reasons, when the wafer 200 is cleaned, the structural peeling of the patterned photoresist can be avoided to completely protect the patterned photoresist and greatly increase the process yield of the wafer 200.

Generally, the time required for the development step of the photolithography process includes the time for supplying the developer, the time during which the photoresist layer 201 reacts with the developer, and the time for cleaning the wafer 200. In addition, it is necessary to consider that part of the photoresist layer 201 is required to be cleaned for a long time to completely remove impurities. Since the nozzle 113 sprays the cleaning liquid to a plurality of positions of the wafer 200, the time required for the development step is greatly reduced, and the development process is accelerated.

After cleaning the wafer 200, the nozzle 113 is typically moved back to its original position, such as the first position P1 corresponding to the center of the wafer 200, although the invention is not limited thereto. The nozzle 113 can also be moved to other locations, such as a fourth position P4 located outside the edge of the wafer 200 (see Figure 3A).

The wafers with multiple dies are tested for yield. During the test, the rotational speed of the wafer is 700 rpm to 2000 rpm, and the lengths of the first, second and third periods are each 5 seconds, and the distance between the first and second positions P1 and P2 is 5 mm. The distance between the third position P2 and P3 is 10 mm, and the number of repetitions of the paths P1-P3 is 1 to 5 times, and the total cleaning time of the wafer is less than 60 seconds. Please refer to FIG. 3B, which is a schematic diagram of fixing the nozzle 113 at a position above the center of the wafer (first position P1) during the cleaning process as a comparison pattern. After the cleaning of the wafer as the test, the defect generated on the wafer is further calculated, and the defect includes the collapsed photoresist layer portion and the damaged crystal lattice, and the number of defects is recorded in Tables 1 and 2, wherein Table 1 records the test results of the wafer at different speeds, and Table 2 records the test results at a fixed speed (1000 rpm) and different repetition times. In Table 1 and Table 2, DD represents the number of destroyed crystal lattices obtained after cleaning the wafer according to the cleaning method of the present embodiment, and DC represents the number of collapsed portions of the photoresist layer, and DC-Base and DD-Base are Experimental data of the control group.

Please refer to Figures 4 and 5 for a schematic diagram of the curves plotted in Tables 1 and 2. From the test results of Tables 1 and 4, it can be observed that the number of defects measured at 2000 rpm is much larger than the number of defects 4.8 at 1500 rpm, so that the rotational speed of the wafer is preferably less than 2000 rpm. It is also worth noting that the test results with movable nozzles are superior to the nozzle-fixed tests. Taking the test at a rotational speed of 1000 rpm as an example, the number of defects obtained by testing with a movable nozzle was 16.8, and that of the fixed nozzle (control group) was 37.5.

In addition, as shown in Table 2 and Figure 5, in the tests of different repetition times, the number of defects obtained by the test with the movable nozzle was smaller than the number of defects of the fixed nozzle. From the test results recorded above, it is clear that the semiconductor cleaning method and apparatus of the preferred embodiment of the present invention can produce a high quality wafer product.

The semiconductor cleaning method and apparatus of the preferred embodiment of the present invention can be applied to chemical mechanical polishing/planarization (CMP) or other semiconductor processes in addition to the above-described photolithography process.

Compared with the conventionally used process apparatus and method, the semiconductor cleaning method and apparatus and the control method thereof according to the preferred embodiment of the present invention dynamically control the position of the nozzle to spray the cleaning liquid, so that the movement trajectory of the nozzle is more flexible. In addition, since the nozzle can spray the cleaning liquid to different parts of the wafer during the cleaning process, the cleaning liquid is prevented from being concentrated at a specific position of the photoresist layer, thereby dispersing the impact force of the cleaning liquid and shortening the time for cleaning the wafer. It also reduces the chance of destroying the structure of the photoresist layer. And during the spraying of the cleaning liquid on the nozzle, the wafer is continuously rotated to generate centrifugal force to pull the cleaning liquid, and it is easier to rinse the developing solution and the dissolved photoresist to increase the efficiency of cleaning the wafer. Based on the above test results, the semiconductor cleaning method and apparatus and the control method thereof according to the preferred embodiment of the present invention can indeed reduce the number of wafer defects and effectively improve the process yield of the semiconductor process.

In conclusion, the present invention has been disclosed in the above preferred embodiments, and is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100‧‧‧Semiconductor cleaning device

101‧‧‧ Carrier

103‧‧‧Development supply unit

105‧‧‧Rotary drive components

107‧‧‧cleaning fluid supply element

109, 110‧‧‧ action drive components

111‧‧‧ Controller

112, 113‧‧‧ nozzle

200‧‧‧ wafer

201‧‧‧Photoresist layer

201A‧‧‧Unwanted photoresist

P1, P2, P3, P4‧‧‧ first, second, third and fourth positions

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of a semiconductor cleaning apparatus in accordance with a preferred embodiment of the present invention.

2A is a flow chart of a method of controlling semiconductor cleaning in accordance with a preferred embodiment of the present invention.

2B is a flow chart of a semiconductor cleaning method in accordance with a preferred embodiment of the present invention.

Figure 3A is a schematic illustration of the movable nozzle resting on different locations on the wafer.

Fig. 3B is a schematic view showing the nozzle being fixed at a position above the center of the wafer (first position P1) during the cleaning process.

Figures 4 and 5 are schematic views of the curves plotted for the data in Tables 1 and 2, respectively.

Claims (12)

A semiconductor cleaning method comprising the steps of: providing a developing solution to a pre-exposed photoresist layer on a wafer by a first action driving element fixedly disposed outside the wafer; One of the nozzles at a position above the center of the circle sprays a cleaning liquid to the photoresist layer for a period of time, wherein the cleaning liquid does not react with the photoresist layer; and is fixedly disposed outside the wafer And a second motion driving component opposite to the first motion driving component, wherein the nozzle moves horizontally relative to the second motion driving component to at least one of the wafers along a radial direction of the wafer Positioning the nozzle in the at least one lower position for at least another period of time to spray the cleaning liquid to the photoresist layer; and cleaning the wafer until the developer and the photoresist dissolved in the developer are washed away So far, the photoresist is patterned to expose one of the wafers. The semiconductor cleaning method of claim 1, wherein the central upper position of the wafer is a first position, and the nozzle is continued for the first time for the first time, the nozzle is further Staying in a second position for a second period of time and staying in a third position for a third period of time. The semiconductor cleaning method of claim 2, wherein the second position is between the first position and the third position. The semiconductor cleaning method of claim 2, wherein the first period of time, the second period of time, and the third period of time are each about 20 seconds. The semiconductor cleaning method of claim 2, further comprising the steps of: moving the nozzle from the third position back to the first position; and causing the nozzle to spray the first time from the first position Wash the cleaning solution to the photoresist layer. The semiconductor cleaning method of claim 5, wherein the path of the nozzle moving along the first position to the third position is repeated 2 to 5 times. A semiconductor cleaning device comprising: a carrier for carrying a wafer, wherein the wafer has a pre-exposed photoresist layer; a developer supply element having a first nozzle for providing a development Liquid is applied to the wafer; a first action driving component is fixedly disposed outside the wafer for moving the first nozzle horizontally relative to the first motion driving component along a radial direction of the wafer; a rotary driving element for rotating the carrier and the wafer on the carrier, thereby uniformly dispersing the developer on the photoresist layer; a cleaning liquid supply component having a second nozzle for Spraying a cleaning liquid, wherein the cleaning liquid does not react with the photoresist layer; a second action driving component is fixedly disposed outside the wafer and opposite to the first motion driving component Having the second nozzle move horizontally relative to the second motion driving element along a radial direction of the wafer; and a controller for controlling the cleaning liquid supply element and the second action a driving element, wherein after the unnecessary photoresist is dissolved in the developing solution, the controller controls the second nozzle to stay at a plurality of positions on the wafer, and sprays the cleaning liquid for the same or different length of time . The semiconductor cleaning device of claim 7, wherein the controller is a programmable controller. The semiconductor cleaning device of claim 7, wherein the controller is preset with a first position of the second nozzle, a second position and a third position, the first position Above the center of the wafer, the second location is between the first position and the third position. The semiconductor cleaning device of claim 9, wherein the second nozzle is in the first position, the second position, and the third position, each of which is about 20 seconds. The semiconductor cleaning device of claim 9, wherein the controller controls the second nozzle staying at the third position to move back to the first position, and controls the second nozzle to spray the cleaning liquid to On the photoresist layer. The semiconductor cleaning device of claim 11, wherein the path of the second nozzle moving along the first position to the third position is repeated 2 to 5 times.