JP7709859B2 - Liquid treatment apparatus and liquid treatment method - Google Patents

Description

This disclosure relates to a liquid processing device and a liquid processing method.

Patent Document 1 discloses a paddle-type photoresist developing device that supplies developing solution from a nozzle onto a workpiece held by a chuck device, and after a certain time has passed, rotates a spinner that constitutes the chuck device to shake off the developing solution on the workpiece. The developing device is equipped with a nozzle that mixes the developing solution with air and sprays a mist of developing solution, and at least a portion of the developing solution piping leading to the nozzle is located within a circulation path for temperature-controlled water.

JP 2004-274028 A

The technology disclosed herein controls the temperature distribution within the substrate surface when forming a puddle of processing liquid on the substrate and processing the substrate with the liquid.

One aspect of the present disclosure is a liquid processing apparatus that performs liquid processing on a substrate using a processing liquid, the liquid processing apparatus having a substrate holding section that holds and rotates the substrate, and a spray nozzle positioned above the substrate held by the substrate holding section that sprays a liquid that does not promote the liquid processing onto an area within the surface of the substrate including the center of the substrate, the liquid processing being a development processing, the processing liquid being a developer, and the liquid being water, and the temperature of the substrate or the developer on the substrate is controlled by the heat of vaporization of the water sprayed by the spray nozzle .

According to the present disclosure, when forming a puddle of processing liquid on a substrate and processing the substrate with the liquid, it is possible to control the temperature distribution within the substrate surface.

1 is a side cross-sectional view that typically illustrates an outline of the configuration of a developing device according to an embodiment of the present invention. FIG. 2 is an explanatory diagram showing a process sequence of a developing method according to an embodiment of the present invention. 1 is a graph showing temperature changes over time at the center and edge of a wafer on which a puddle of developer has been formed. 1 is a graph showing the temperature change over time at the center and edge of a wafer when a puddle of developer is sprayed onto the wafer. 13 is a graph showing the change over time in temperature at the center and edge of a wafer when a single spray is applied to the wafer before a puddle is formed. 13 is a graph showing the change over time in temperature at the center and edge of a wafer when the wafer is sprayed three times before a puddle is formed. FIG. 13 is an explanatory diagram showing a state in which spraying is performed from above at a position eccentric to the center of the wafer. FIG. 13 is a plan view of a wafer showing a spray area when spraying from above at a position eccentric to the center of the wafer. FIG. 13 is an explanatory diagram showing a state in which spraying is performed obliquely from above the wafer. FIG. 10 is an explanatory diagram showing a state where spraying is performed by a spray nozzle having two spray portions.

For example, in the manufacturing process of semiconductor devices, a liquid process is carried out in which a resist film is formed on the surface of a substrate such as a semiconductor wafer (hereinafter sometimes referred to as a "wafer"), a pattern is exposed to light, and then development is carried out. When developing, a puddle of developer is formed on the substrate, and development is carried out.

In this case, if the temperature of the substrate surface during paddle development is non-uniform, the dimensional uniformity of the line width of the developed pattern deteriorates. That is, for example, during paddle development, there is a difference in temperature fluctuation from the center to the edge of the substrate, which results in variation in the line width of the pattern from the center to the edge of the substrate. This tendency is particularly noticeable with i-line resists, which have high temperature sensitivity during development processing.

In the technology described in Patent Document 1, at least a portion of the developer piping leading to the nozzle that mixes the developer with air and sprays the developer in a mist form is arranged within the temperature-controlled water circulation path, but there is room for improvement in the temperature uniformity on the surface during paddle development.

The technology disclosed herein controls the temperature distribution within the substrate surface when forming a paddle on the substrate and developing the substrate. This allows liquid processing such as development to be controlled for each region, making it possible to improve the uniformity of line width within the substrate surface after development, for example.

The configuration of the developing device according to this embodiment will be described below with reference to the drawings. Note that in this specification, elements having substantially the same functional configuration will be assigned the same reference numerals to avoid redundant description.

Figure 1 shows a side cross-sectional view that shows a schematic outline of the configuration of a developing apparatus 1 as a liquid processing apparatus according to this embodiment. The developing apparatus 1 has a spin chuck 11 as a substrate holding unit inside a housing 10. The spin chuck 11 holds a wafer W as a substrate horizontally. The spin chuck 11 is connected to a rotating unit 12 that can be raised and lowered, and the rotating unit 12 is connected to a rotation drive unit 13 constituted by a motor or the like. Therefore, the held wafer W can be rotated by driving the rotation drive unit 13.

A cup 21 is placed outside the spin chuck 11 to prevent the developer, cleaning solution, and their mists from scattering to the surroundings. A drain pipe 23 and an exhaust pipe 24 are provided at the bottom 22 of the cup 21. The drain pipe 23 is connected to a drainage device 25 such as a drainage pump. The exhaust pipe 24 is connected via a valve 26 to an exhaust device 27 such as an exhaust pump. With this configuration, the atmosphere around the wafer W held by the spin chuck 11 is exhausted from the exhaust pipe 24. Therefore, the exhaust pipe 24 and the exhaust device 27 form an exhaust section.

An air blower 14 is provided at the top of the housing 10 of the developing device 1 to supply air at the required temperature and humidity as a downflow into the cup 21.

When forming a puddle of developer on the wafer W, a developer nozzle 31 is used. This developer nozzle 31 is attached to a nozzle support 32, such as an arm, which can be moved up and down by a drive mechanism (not shown) as indicated by the dashed reciprocating arrow A (Z direction) and can also move horizontally as indicated by the dashed reciprocating arrow B (X direction). Developer nozzle 31 is supplied with developer from a developer supply source 34 via a supply pipe 33.

When forming the paddle, if a so-called long nozzle with a discharge port having a length equal to or greater than the diameter of the wafer W is used, a paddle of the developer can be formed on the wafer W by scanning from one end to the other end of the wafer W. In the case of a so-called straight type nozzle that discharges liquid to form a liquid column with a width sufficiently small compared to the diameter of the wafer W, the discharge port is positioned above the center of the wafer W, and the developer is discharged while rotating the wafer W, thereby spreading the developer over the entire surface of the wafer W and forming a paddle of the developer on the wafer W. The paddle of the developer can also be formed by scanning a straight type nozzle over the wafer W in the same way as a long nozzle, or by arranging multiple discharge ports for discharging liquid like a straight type nozzle over the wafer W and supplying the developer from each of the discharge ports.

The spray nozzle 41 has a nozzle body 42. The nozzle body 42 is attached to a nozzle support part (not shown) such as an arm, and the nozzle support part can be raised and lowered by a drive mechanism (not shown) as indicated by the reciprocating arrow C (Z direction) shown by the dashed line in the figure, and can also be moved horizontally as indicated by the reciprocating arrow D (X direction) shown by the dashed line.

The spray nozzle 41 in the embodiment has a spray section 43 and a cleaning liquid supply nozzle 44. The liquid and gas supplied from a supply source 45 of a liquid that does not promote development, such as water, and a supply source 46 of a gas used for spraying (e.g., clean air or an inert gas such as nitrogen gas) are mixed in a mixing section 47 and supplied to the spray section 43, from which a mist of the liquid is sprayed. A cleaning liquid is supplied to the cleaning liquid supply nozzle 44 from a cleaning liquid supply source 48. The cleaning liquid supply nozzle 44 is used when cleaning the developing liquid from the wafer W after development. Note that an inert gas is more preferable as the gas used for spraying so as not to inadvertently affect the liquid processing.

The developing device 1 is controlled by a control device 100, which is a control unit. The control device 100 is, for example, a computer equipped with a CPU, memory, etc., and has a program storage unit (not shown). The program storage unit stores various programs that control the developing process of the wafer W in the developing device 1. The above programs may be recorded on a computer-readable storage medium and installed from the storage medium into the control device 100. It does not matter whether the storage medium H is a temporary storage medium or a non-temporary storage medium.

Examples of control include a series of processes from development to cleaning and drying. For example, the movement of the developer nozzle 31 and the spray nozzle 41, the start and stop of spraying from the spray unit 43, the supply and stop of cleaning liquid from the cleaning liquid supply nozzle 44, the rotation and stop of the spin chuck 11, the series of sequences of the development process, and even the operation of the air blower 14, the drainage device 25, the valve 26, and the exhaust device 27 are also controlled.

Next, a developing method using the developing apparatus 1 having the above configuration will be described with reference to Figs. 2(a)-(e). This developing method is an example in which a so-called long nozzle with a discharge port having a length equal to or greater than the diameter of the wafer W is used as the developer nozzle 31. First, the developer nozzle 31 horizontally scans the wafer W from one end to the other while supplying developer onto the wafer W held on the spin chuck 11 (Fig. 2(a)). As a result, a puddle K of developer is formed on the wafer W, and the wafer W is statically developed (Fig. 2(b)). When the puddle K is formed, the developer nozzle 31 retreats to a standby position.

Then, as shown in FIG. 2(c), the spray nozzle 41 moves toward the center of the wafer W and stops at a predetermined position. In this case, the predetermined position is where the spray unit 43 is located above the center of the wafer W.

As shown in FIG. 2(d), water is sprayed from the spray unit 43 onto the paddle K on the wafer W as a liquid that does not promote development. When the water is sprayed, the mist of water evaporates just before it reaches the paddle K, and the temperature of the surface of the paddle K drops due to the latent heat of evaporation (temperature control process). In this case, the spin chuck 11 may or may not rotate. Details of the timing and number of sprays will be described later.

After that, when the in-plane temperature control of the paddle K by spraying from the spray portion 43 of the spray nozzle 41 is completed, the spray nozzle 41 moves, as shown in FIG. 2(e), so that the center of the cleaning liquid supply nozzle 44 moves to the center of the wafer W and stops. After that, while rotating the wafer W, the cleaning liquid supply nozzle 44 supplies cleaning liquid F toward the center of the wafer W, so that the developing liquid that formed the paddle K is shaken off and the surface of the wafer W is cleaned with the cleaning liquid F.

The development process shown in FIG. 2 is an example in which a long nozzle with a discharge port having a length equal to or greater than the diameter of the wafer W is used as the developer nozzle 31. However, when the straight type nozzle described above is used as the developer nozzle 31, only the process of forming the paddle K is different. That is, the developer is supplied toward the center of the wafer W while rotating the wafer W, and the supplied developer is spread over the entire surface of the wafer W by centrifugal force to form the paddle K. The process after the paddle is formed is the same as that shown in FIG. 2(b) to (e). In this case, when discharging using a straight type nozzle as the developer nozzle 31, when discharging the developer by arranging multiple discharge ports on the wafer W, the multiple discharge ports are arranged in the depth direction at a position overlapping with the developer nozzle 31, and they are moved together like the developer nozzle 31.

However, according to the knowledge of the inventors, it has been found that the temperature distribution within the surface of the paddle K has a greater temperature drop in the peripheral area than in the center. To explain this with reference to a diagram, FIG. 3 shows the temperature change in the center and peripheral area of the wafer W after the formation of the paddle K of the developer, where the thick line shows the temperature change in the center and the thin line shows the temperature change in the peripheral area. The reason why the temperature drop in the peripheral area is greater than in the center is thought to be because exhaust is performed from the outside of the peripheral area of the wafer W. If the temperature drop in the peripheral area is greater than in the center, this affects the uniformity of the development process, resulting in non-uniform line widths in the developed pattern.

For example, as shown in FIG. 4, when the above-mentioned liquid is sprayed from the spray portion 43 of the spray nozzle 41 toward the paddle 15 seconds after the paddle is formed (S in the figure), it was confirmed that the rate of decrease in the center of the wafer W is accelerated more than in the case of FIG. 3, and the temperature difference T between the center and the periphery of the wafer W 60 seconds after the paddle is formed is smaller than in FIG. 3. As a result of actual measurement, the temperature difference T between the center and the periphery after 60 seconds in FIG. 3 is about 1.2°C, whereas in the sprayed example of FIG. 4, the temperature difference T between the center and the periphery after 60 seconds is about 0.5°C, less than half.

In this way, it was confirmed that the temperature of the center of the paddle K can be lowered by spraying the liquid in a cone shape from above the center of the surface of the paddle K after the paddle K is formed. In the above example, the total spray amount was 2.5 ml. More specifically, FIG. 4 shows an example of 25 sprays using a spray nozzle 41 that sprays 0.1 ml per time. The spray height (height from the surface of the paddle K to the spray nozzle of the spray section 43) was 150 mm. Considering the function of lowering the temperature of the paddle K on the surface of the wafer W by the heat of vaporization, it is preferable that the sprayed liquid mist is completely vaporized just before the surface of the paddle K, and therefore the spray amount, spray height, and even the particle size of the sprayed mist are preferably determined from this point of view.

From this viewpoint, it is considered preferable that the amount of spray is 0.1 ml to 0.5 ml per spray, the spray height is 12 mm to 150 mm, and the particle size of the mist is, for example, 0.1 μm to 5.0 μm. Even if the spray height is, for example, 12 mm, which is a position relatively close to the substrate, it is preferable that the sprayed liquid is sufficiently diffused radially and vaporized before reaching the wafer W or the paddle K.
Furthermore, in this embodiment, the liquid sprayed from the spray portion 43 of the spray nozzle 41 is a liquid that does not promote development, so even if some mist of the liquid adheres to the surface of the paddle K, it will not significantly affect the development process.

Further investigations have shown that spraying during the development process, after the formation of the puddle K, is more sensitive to temperature. Therefore, spraying during the first half of the process is more suitable for controlling the temperature of the puddle K.

Also, a liquid obtained by diluting the developer may be sprayed as the liquid sprayed from the spray portion 43 of the spray nozzle 41. In this way, even if the mist produced by spraying adheres to the paddle K, there is almost no change in the concentration of the developer, and therefore it is possible to further suppress the influence on the development process.
In the technology described in the special document 1, the temperature of the discharged air is adjusted by heating, but the inventors' knowledge shows that even if air at 18°C to 28°C is sprayed onto the developing paddle, it has almost no effect on the wafer W as long as the developing paddle is present, and temperature control is not possible. In this respect, the technology disclosed herein sprays mist that is easily vaporized even after the paddle is formed, so that the temperature of the spray area can be quickly lowered and the development process can be controlled by temperature. Moreover, in the technology disclosed herein, the temperature is adjusted in this way while the development process is proceeding with a paddle of the developer. Of course, there is no need to adjust the temperature of the mist of the liquid to be sprayed.

In the above example, the puddle K of developer is formed on the surface of the wafer W, and then the developer is sprayed onto the puddle. However, the present invention is not limited to this, and the liquid may be sprayed directly onto the wafer W before the puddle K is formed. In addition, the number of times the developer is sprayed may not be just once, but multiple times.

Figure 5 shows the temperature change at the center and edge of a wafer W that does not have a paddle K formed when it is sprayed once at the 10 second mark, with the thick line indicating the center and the thin line indicating the temperature change at the edge. In this case, the temperature at the edge is higher than the temperature at the center. This is because the paddle K is not formed, so the temperature of the wafer W remains constant at about the ambient temperature inside the device (usually 23°C). In this state, for example, if spraying is performed from a spray height of 75 mm, there will be areas on the edge of the wafer W where the mist does not reach, and the edge temperature, which is larger in area, will be about 23°C when the data is averaged.

In contrast, FIG. 6 shows the temperature change at the center and edge of the wafer W after 10 seconds when spraying was performed three times. The thick line in the figure shows the temperature change at the center, and the thin line shows the temperature change at the edge. In this way, by spraying the wafer W multiple times, the temperature of both the center and edge can be lowered more than in the case of spraying once as shown in FIG. 5. However, since the spray is performed from above the center of the wafer W, the mist tends to collect and form a liquid pool in the center, making it difficult to promote volatilization, and the result was that the temperature drop was not large considering the number of sprays. In addition, since there is no processing liquid such as a developing liquid on the wafer W, pure water is used as the liquid and sprayed, so even if the pure water mist adheres to the wafer surface, it does not affect the subsequent liquid processing such as development.

In the above example, the spray section 43 of the spray nozzle 41 was positioned above the center of the wafer W to spray, but this is not limiting and spraying may be performed from above a position eccentric to the center of the wafer W, as shown in FIG. 7. As mentioned above, after the formation of the puddle K, the temperature drop at the peripheral edge of the wafer W is greater. In such a case, the area sprayed from the spray section 43 should be sprayed onto an area including the center P of the wafer W, as shown in FIG. 8.

Even in such a case, it is not necessary to rotate the wafer W by driving the spin chuck 11, and it is possible to lower the temperature of a specific area of the paddle K. For example, when the resist on the wafer W is an i-line resist, it is known that the lower the temperature, the more the development process will progress. Therefore, the temperature of a specific area can be lowered to promote the development process. Using this, the following temperature control becomes possible. For example, when forming a paddle K of developer, if the supply starts from one end of the wafer W, the development process will progress more at that end than at the other end where the supply ends. To correct this, it is possible to spray the other end and lower the temperature from the one end, thereby promoting the development process at one end and allowing it to catch up with the development process at the other end.

From this perspective, as shown in FIG. 9, when spraying the wafer W held by the spin chuck 11, the spray portion 43 of the spray nozzle 50 may be tilted obliquely from the vertical direction of the center of the wafer W. In such a case, the spin chuck 11 may or may not be rotated. In other words, the rotation may be selected appropriately according to the area where the temperature is to be lowered.

The spray nozzle 41 described above has one spray part, but it is not limited to this and may have multiple spray parts, for example two spray parts 43a and 43b, like the spray nozzle 50 shown in Figure 10.

That is, the spray nozzle 50 shown in FIG. 10 has a spray section 43a that sprays the center of the wafer W and a spray section 43b that sprays the peripheral portion of the wafer W. By using a spray nozzle having such a configuration, the spray sections 43a, 43b can be controlled by the control device 100 so that, for example, the center of the surface of the wafer W is sprayed for a longer period of time than the peripheral portion. This makes it possible to spray the center of the wafer W for a longer period of time, thereby decreasing the temperature more than the peripheral portion.

Furthermore, it is possible to spray only the center and stop spraying the peripheral area or spray less than the center. This allows for more precise temperature control of each area of the wafer W by spraying.

In the above example, the flow rate of the spray from the spray part of the spray nozzle is not specifically explained, but since the development process is in progress after the formation of the puddle K, it is advisable to spray at a flow rate that does not expose the surface of the wafer W. If the surface becomes exposed, the development process of the exposed portion will stop.

The amount of exhaust while spraying from the spray nozzles 41, 50 is smaller than the amount of exhaust when cleaning the wafer W after liquid processing. This is because there is no need to pay special attention to the temperature within the surface of the wafer W after liquid processing, while a large amount of mist of cleaning liquid is generated during cleaning, which must be exhausted quickly. Also, not disturbing the spray flow during spraying allows for optimal temperature control.

The spray nozzle 41 described above is configured with the spray section 43 and the cleaning liquid supply nozzle 44 integrated together, but it may be configured separately from the cleaning liquid supply nozzle, as in the case of the spray nozzle 50.

The above example is particularly effective for developing temperature-sensitive i-line resist, but of course it is not limited to this, and the present disclosure is also effective for developing resist exposed to energy rays such as g-line, KrF excimer laser, and ArF excimer laser.

The embodiments disclosed herein should be considered in all respects as illustrative and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

REFERENCE SIGNS LIST 1 Developing device 10 Housing 11 Spin chuck 12 Rotating section 13 Rotation drive section 14 Air blower 21 Cup 22 Bottom section 23 Drain pipe 24 Exhaust pipe 25 Drain device 26 Valve 27 Exhaust device 31 Developing solution nozzle 32 Nozzle support section 41, 50 Spray nozzle 42 Nozzle body 43, 43a, 43b Spray section 44 Cleaning solution supply nozzle 100 Control device F Cleaning solution K Paddle W Wafer

Claims (11)

A liquid processing apparatus for performing liquid processing on a substrate using a processing liquid,
a substrate holder that holds and rotates the substrate;
a spray nozzle positioned above the substrate held by the substrate holder and spraying a liquid that does not promote the liquid treatment onto an area within a surface of the substrate including a center of the substrate ;
the liquid treatment is a development treatment, the treatment liquid is a developer, and the liquid is water;
A liquid processing apparatus that controls a temperature of the substrate or the developing solution on the substrate by heat of vaporization of the water sprayed by the spray nozzle . A control unit for controlling the spray nozzle,
The liquid treatment apparatus according to claim 1 , wherein the control unit is configured to spray the liquid from the spray nozzle at least during a first half of a development treatment time using the developer after a puddle of the developer is formed on the surface of the substrate. A liquid processing apparatus that forms a puddle of a developer, which is a processing liquid, on a substrate to develop the substrate, comprising:
a substrate holder that holds and rotates the substrate;
a spray nozzle positioned above the substrate held by the substrate holder and configured to spray a diluted liquid of the developer onto an area within a surface of the substrate including a center of the substrate;
A control unit for controlling the spray nozzle;
having
A liquid processing apparatus that controls a temperature of the substrate or the developing solution on the substrate by heat of vaporization of the liquid sprayed by the spray nozzle . A liquid processing device according to claim 2 or 3, wherein the control unit is configured so that the spray nozzle sprays multiple times during the development process using the developer. A control unit for controlling the spray nozzle,
The liquid processing apparatus according to claim 1 , wherein the control unit is configured such that the spray nozzle sprays the liquid onto an area within a surface of the substrate, including a center of the substrate, before the processing liquid is supplied onto the substrate. the spray nozzle has a spray portion that sprays the central portion of the substrate and another spray portion that sprays the peripheral portion of the substrate,
6. The liquid treatment apparatus according to claim 2, wherein the control unit is configured to spray the liquid on a central portion of the surface of the substrate for a longer period of time than on a peripheral portion of the surface of the substrate. the spray nozzle has a spray portion that sprays the central portion of the substrate and another spray portion that sprays the peripheral portion of the substrate,
The liquid treatment device according to any one of claims 2 to 5, wherein the control unit is configured to spray the liquid toward a central portion of the surface of the substrate while not spraying the liquid toward a peripheral portion of the surface of the substrate. The liquid processing device according to any one of claims 2 to 7, in which, when sprayed toward a puddle of the processing liquid formed on the substrate on which liquid processing is in progress on the surface of the substrate, the spray is performed at a flow rate such that the surface of the substrate is not exposed by the spray. an exhaust unit configured to exhaust an atmosphere around the substrate held by the substrate holder;
The liquid processing apparatus according to any one of claims 2 to 8, wherein the control unit is configured to control the exhaust unit so that an exhaust volume while the liquid is being sprayed from the spray nozzle is smaller than an exhaust volume while the substrate is being cleaned after the liquid processing of the substrate is completed. A liquid processing apparatus according to any one of claims 1 to 9, in which when spraying from the spray nozzle onto the substrate held by the substrate holder, the spray is tilted obliquely from the vertical direction of the center of the substrate. A liquid processing method for performing liquid processing on a substrate, comprising the steps of:
A liquid is sprayed onto an area within a surface of the substrate, including a center of the substrate, from above a substrate holder that holds and rotates the substrate;
A liquid processing method, comprising controlling a temperature of the substrate or the processing liquid on the substrate by heat of vaporization of the sprayed liquid.