Shutter device used for exposure in lithography machine, and method for use thereof

A shutter device for use in exposure by a photolithography machine and a method of using the shutter device are disclosed. The device includes a shutter blade (1); a rotating motor (2) for driving the shutter blade (1) to rotate; a controller in electric connection with the rotating motor (2); and a supporter (3) for supporting the rotating motor (2). The shutter blade (1) includes a rotation center (11) and, disposed in correspondence with the rotation center (11), at least one open portion (12) and at least one shielding portion (13). The rotation center (11) is coupled to the rotating motor (2) which drives the shutter blade (1) to rotate so that the shutter device opening and closure are accomplished to enable and disable exposure. The shielding portion (13) includes a hollow portion (131) which significantly reduces the mass of the shutter blade (1), thereby facilitating the control over the rotation of the shutter blade (1). Under the control of the controller, the opening and closing of the shutter is accomplished during rotation of the shutter blade (1) at a constant speed, while the acceleration and deceleration of the shutter blade (1) take place in the period when the shutter device is in a closed state, which is relatively long and allows a large stroke. This significantly reduces the required torque of the rotating motor (2) and effectively shortens the shutter opening and closing time.

TECHNICAL FIELD

The present invention relates to the manufacturing of photolithography equipment and, more particular, to a shutter device for use in exposure by a photolithography machine and a method of using the shutter device.

BACKGROUND

Photolithography is a technique for printing a pattern with features onto the surface of a substrate. A commonly-used substrate is a semiconductor wafer or a glass substrate having a surface coated with a light-sensitive material (e.g., photoresist). During a photolithography process, a wafer is placed on a wafer stage and the pattern is projected onto the surface of the wafer by means of an exposure device incorporated in the photolithography machine.

One of the important metrics for assessing the performance of a photolithography machine is exposure dosage, because the development of the photoresist will be affected at excessively high or low exposure doses. For this reason, exposure dose control accuracy poses a direct impact on the etching accuracy of the photolithography machine.

Exposure systems in existing medium-end and low-end photolithography machines employ high-pressure mercury lamps as their light sources. Such an exposure system utilizes a mechanical shutter disposed in the optical path to enable or disable exposure, and the exposure dose is determined by the exposure time.

Specifically, this operation may involve:

1) stabilizing an output optical power of the high-pressure mercury lamp by preheating or environmental control;

2) calculating the exposure time, opening the shutter to enable exposure and concurrently starting a timer; and

3) upon the expiration of the exposure time, closing the shutter to disable exposure.

In recent years, the output power of mercury lamps has been on a rise. This means that, at the same exposure dose, the time required for the opening and closing of the shutter must be shortened. However, due to the structural limitations of the conventional mechanical shutter, the shutter opening and closing time is already close to the limit, and increasing the power of the shutter simply increases the burden on the control system. Further, frequent overpowered operations may impair the stability of the system.

In order to overcome the above problem, there has been disclosed in the prior art a shutter device for use in an exposure sub-system of a photolithography machine, which can be quickly opened and closed under the action of high-power voice coil motors. However, in order to achieve a shorter shutter opening and closing time, the voice coil motors often have to operate at high power levels. Additionally, the voice coil motors themselves fail to meet the practical needs in terms of reliability and stability. As a result, many problems may arise from the operation of the shutter, which may ultimately affect the stability and performance of the photolithography tool in which the shutter device is employed.

SUMMARY OF THE INVENTION

It is an objective of the present invention to solve the above-described low-reliability and low-stability problems with the prior art by presenting a shutter device for use in exposure by photolithography machine and a method of using the shutter device.

The above objective is attained by the subject matter of the present invention which lies in a shutter device for use in exposure by a photolithography machine, including: a shutter blade; a rotating motor for driving the shutter blade to rotate; a controller in electric connection with the rotating motor; and a supporter for supporting the rotating motor, the shutter blade including a rotation center and, disposed in correspondence with the rotation center, at least one open portion and at least one shielding portion, the rotation center coupled to the rotating motor, the rotating motor driving the shutter blade to rotate so that the shutter device is opened and closed to enable and disable exposure.

Additionally, a coupling block may be disposed between the rotation center of the shutter blade and the rotating motor.

Additionally, a speed reducer may be disposed between the rotating motor and the coupling block.

Additionally, the supporter may be fixedly connected to the speed reducer.

Additionally, the shutter blade may include one open portion and one shielding portion, each of the open portion and the shielding portion having a central angle of 180 degrees.

Additionally, the shutter blade may include two open portions in symmetry with respect to the rotation center and two shielding portions also in symmetry with respect to the rotation center, wherein each of the open and shielding portions has a central angle of 90 degrees.

Additionally, the shutter blade may include three open portions and three shielding portions, which are staggered one another around the rotation center and each have a central angle of 60 degrees.

Additionally, the shielding portion may include an inner hollow portion and an outer shielding portion that is concentric with the inner hollow portion with respect to the rotation center.

Additionally, the hollow portion may be fan-shaped, with the shielding portion may be annular-shaped.

Additionally, during driving, by the rotating motor, of the shutter blade to form an exposure-enabled region and an exposure-disabled region, the motor and/or the shutter blade rotate at a non-zero speed.

The present invention also provides a method of using a shutter device for use in exposure by a photolithography machine, including the steps of:

S1) assembling a shutter blade, a rotating motor, a controller and a supporter, the shutter blade including a rotation center and, disposed in correspondence with the rotation center, at least one open portion and at least one shielding portion; and

S2) activating the rotating motor under control of the controller to cause the shutter blade to rotate so that the shutter device is opened and closed to form an exposure-enabled region and an exposure-disabled region.

Additionally, the shielding portion may include an inner hollow portion and an outer shielding portion that is concentric with the inner hollow portion with respect to the rotation center.

Additionally, the hollow portion may be fan-shaped, with the shielding portion may be annular-shaped.

Additionally, in step S2, during forming an exposure-enabled region and an exposure-disabled region, and subsequent to the activation of the rotating motor under the control of the controller, the shutter blade may be caused to experience acceleration-constant speed-deceleration-stillness-acceleration cycles.

Additionally, acceleration and deceleration of the shutter blade are accomplished during a closing stage of the shutter device, while the shutter blade rotates at a constant speed during an opening stage of the shutter device.

Additionally, in step S2, during forming an exposure-enabled region and an exposure-disabled region, and subsequent to the activation of the rotating motor under the control of the controller, the shutter blade may be caused to experience acceleration-constant speed-deceleration-constant speed-acceleration cycles.

Additionally, acceleration and deceleration of the shutter blade may be accomplished during a closing stage of the shutter device, while the shutter blade rotates at a constant speed during an opening stage of the shutter device.

Additionally, a constant speed at which the rotating motor rotates subsequent to the acceleration may be greater than or equal to 10 times a constant speed at which the rotating motor rotates subsequent to the deceleration.

In the shutter device for use in exposure by photolithography machine and the method of using the shutter device, a shutter blade includes a rotation center and, disposed in correspondence with the rotation center, at least one open portion and at least one shielding portion, the rotation center coupled to a rotating motor which drives the shutter blade to rotate so that the shutter is opened and closed to enable and disable exposure. In addition, the shielding portion includes a hollow portion which significantly reduces the mass of the shutter blade, facilitating the control over the rotation of the shutter blade and improving the exposure dose control accuracy. Further, under the control of the controller, the opening and closing of the shutter is accomplished during rotation of the shutter blade at a constant speed, while the acceleration and deceleration of the shutter blade take place in the period when the shutter is in a closed state, which is relatively long and allows a large stroke. This significantly reduces the required torque of the rotating motor. At the same time, as the constant speed of the rotating motor is relatively high, the shutter opening and closing time is effectively shortened, resulting in a further improvement in the exposure dose control accuracy and in the performance of the photolithography machine.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention will be described below in detail with reference to the accompanying drawings.

As shown inFIGS. 1 to 7, the present invention provides a shutter device for used in exposure by a photolithography machine, including: a shutter blade1; a rotating motor2for driving the shutter blade1to rotate; a controller (not shown) in electric connection with the rotating motor2; and a supporter3for holding the rotating motor2. The shutter blade1includes a rotation center11and at least one open portion12and at least one shielding portion13which are disposed in correspondence with the rotation center11. The rotation center11is coupled to the rotating motor2. The rotating motor2drives the shutter blade1to rotate so that the shutter is opened and closed to enable and disable exposure. In addition, during the enabling and disabling of exposure, the rotating motor2and/or shutter blade1rotate at a non-zero speed.

With continued reference toFIG. 1, between the rotation center11of the shutter blade1and the rotating motor2may be provided a coupling block4configured to effectively fix the rotation center11of the shutter blade1to an output shaft of the rotating motor2to prevent any relative movement between them. In this manner, better control can be achieved over the rotation of the shutter blade1.

With continued reference toFIG. 1, a speed reducer5may be further disposed between the rotating motor2and the coupling block4. Specifically, in this Embodiment, the speed reducer5may have a gear ratio of 4:1. The speed reducer5may be coupled to the output shaft of the rotating motor2so that the speed reducer5can provide a trade-off between speed limit and torque limit of the rotating motor2. As the higher the torque of the rotating motor2, the greater its power, with the use of the speed reducer5, the rotating motor2is capable of outputting a greater torque without an increase in its power.

Preferably, the supporter3is fixedly connected to the speed reducer5. In particular, the supporter3is disposed under the speed reducer5so as to support the whole structure of the shutter device.

As shown inFIG. 2, the shutter blade1may have two open portions12in symmetry with respect to the rotation center11and two shielding portions13also in symmetry with respect to the rotation center11. Each of the open portions12and the shielding portions13may have a central angle of 90 degrees.

Preferably, each of the shielding portions13may have an inner hollow portion131and an outer scanning light shielding portion132that is concentric with the inner hollow portion with respect to the rotation center11. As shown inFIG. 2, the hollow portions131may be fan-shaped and can effectively reduce the mass of the shutter blade, which facilitates the control over the rotation of the shutter blade and hence improves the exposure dose control accuracy. The scanning light shielding portions132may be annular-shaped which can block the light beam6during the rotation of the shutter blade1and thus disable exposure.

As shown inFIGS. 3aand 3b, when the shielding portion132shields the light beam6, exposure is disabled, which is equivalent to a closed state of the shutter. As shown inFIGS. 4aand 4b, when the light beam6is not blocked by the shielding portions132, i.e., the light beam6passes through one of the open portions12, exposure is allowed, which is equivalent to a fully-open state of the shutter. As shown inFIGS. 5aand 5b, when the light beam6partially passes through an open portion12and is partially blocked by the shielding portion132, the shutter is in a partially-open, partially-closed state.

The present invention also provides a method of using a shutter device for use in exposure by a photolithography machine, which include the steps as detailed below.

In S1, a shutter blade1, a rotating motor2, a controller and a supporter3are assembled. The shutter blade1includes a rotation center11and, disposed in correspondence with the rotation center11, at least one open portion12and at least one shielding portion13. The shielding portion13may have an inner hollow portion131and an outer scanning light shielding portion132that is concentric with the inner hollow portion with respect to the rotation center11. The hollow portion131may be fan-shaped and can effectively reduce the mass of the shutter blade, which facilitates the control over the rotation of the shutter blade and hence improves the exposure dose control accuracy.

In S2, the rotating motor2is activated under the control of the controller, causing the shutter blade1to rotate, thereby enabling and disabling exposure. Preferably, during the enabling and disabling of the exposure, and subsequent to the activation of the rotating motor2under the control of the controller, the shutter blade1is caused to experience acceleration-constant speed-deceleration-stillness-acceleration cycles. As shown inFIG. 6, during a closed stage of the shutter, which stage corresponds to an exposure-disabled region in the figure, the acceleration and deceleration of the shutter blade1are both accomplished. In addition, during an opening stage of the shutter, which stage corresponds to an exposure-enabled region in the figure, the shutter blade1rotates at a constant speed. Specifically, the opening stage of the shutter includes partially-open, partially-closed and fully-open states as shown inFIGS. 3a-5b. Thus, under the control of the controller, the open and closed states of the shutter are configured within the periods during which the shutter blade1rotates at a constant speed, while the acceleration and deceleration of the shutter blade1take place in the a closing stage of the shutter, which is relatively long and allows a large stroke. This significantly reduces the required torque of the rotating motor2. At the same time, as the constant speed of the rotating motor2is relatively high, the shutter opening and closing time is effectively shortened, resulting in a further improvement in the exposure dose control accuracy and in the performance of the photolithography machine.

As shown inFIG. 7, during a constant-speed rotation cycle that experiences the partially-open, fully-open and partially-closed states, the shutter blade1according to this Embodiment has a theoretical exposure dose utilization rate of 58.75%.

Assuming the incident light has an illuminance G and a desired exposure dose is denoted by K, then the exposure time t is:

Since the speed reducer5has a gear ratio of 4:1 and each exposure-disabled period accounts for ¼ of the shutter cycle, the speed P of the rotating motor2is:

Assuming the incident illuminance G=3000 mW/cm2and a minimum of the desired exposure dose K is 80 mJ in this Embodiment, then:

and the speed P of the rotating motor2is:

In this Embodiment, within each exposure-disabled period that accounts for ¼ of the shutter cycle, the rotating motor2has to decrease its speed to zero and subsequently increase the speed to 7661 rpm at an angular acceleration of:

where, V represents the linear speed of the rotating motor2.

On the basis of this, a rotational moment of inertia for the shutter blade1in this Embodiment can be obtained as J=1.2×10−5kg/m2and the torque as:

Under such a condition, in each exposure-disabled period, the rotating motor2needs to operate for 31.3 ms. Based on a required length of the exposure-disabled period, the duration in which the shutter blade1does not rotate and stays still can be determined.

As shown inFIG. 8, this Embodiment differs from Embodiment 1 in that the shutter blade1has one open portion12and one shielding portion13. Each of the open portion12and the shielding portion13has a central angle of 180 degrees. Additionally, the speed reducer5is omitted, and the shutter blade1is directly driven by the rotating motor2instead. Preferably, the shielding portion13includes an inner hollow portion131and an outer scanning light shielding portion132that is concentric with the inner hollow portion with respect to the rotation center11. The hollow portion131may be fan-shaped and can effectively reduce the mass of the shutter blade, which facilitates the control over the rotation of the shutter blade and hence improves the exposure dose control accuracy. The scanning light shielding portion132may be annular-shaped which can block light during the rotation of the shutter blade1and thus disable exposure. In this Embodiment, as the shutter blade1has only one open portion11and only one shielding portion12, the fraction of the period in which the shutter blade1is partially-open or partially-closed in the shutter cycle is reduced, improving the exposure dose utilization rate.

During a constant-speed rotation cycle experiencing the partially-open fully-open and partially-closed states, the shutter blade1according to this Embodiment has a theoretical exposure dose utilization rate of 86.11%.

Assuming the incident light has an illuminance G and a desired exposure dose is denoted by K, then the exposure time t is:

Since the exposure-disabled period accounts for ½ of the shutter cycle, the speed P of the rotating motor2is:

Within the exposure-disabled period that accounts for ½ of the shutter cycle, the rotating motor2has to decrease its speed to zero and subsequently increase the speed to 4491 rpm at an angular acceleration of:

where, V represents the linear speed of the rotating motor2.

On the basis of this, a rotational moment of inertia for the shutter blade1in this Embodiment can be obtained as J=1×10−5kg/m2and the torque as:
T=J×ε×1000=256 mNm  (10)

Under such a condition, in the exposure-disabled period, the rotating motor2needs to operate for 26.7 ms. Based on a required length of the exposure-disabled period, the duration in which the shutter blade1does not rotate and stays still can be determined.

This Embodiment differs from Embodiment 1 in that the shutter blade1has three open portions12and three shielding portions13, which are staggered one another around the rotation center11and each of the open portions12and the shielding portions13has a central angle of 60 degrees. Preferably, each of the shielding portions13includes an inner hollow portion131and an outer scanning light shielding portion132that is concentric with the inner hollow portion with respect to the rotation center11. The hollow portion131may be fan-shaped and can effectively reduce the mass of the shutter blade, which facilitates the control over the rotation of the shutter blade and hence improves the exposure dose control accuracy. The scanning light shielding portion132may be annular-shaped which can block light during the rotation of the shutter blade1and thus disable exposure.

During a constant-speed rotation cycle experiencing the partially-open fully-open and partially-closed states, the shutter blade1according to this Embodiment has a theoretical exposure dose utilization rate of 50%.

Assuming the incident light has an illuminance G and a desired exposure dose is denoted by K, then the exposure time t is:

Since the speed reducer5has a gear ratio of 4:1 and the exposure-disabled period accounts for ⅙ of the shutter cycle, the speed P of the rotating motor2is:

Within the exposure-disabled period that accounts for ⅙ of the shutter cycle, the rotating motor has to decrease its speed to zero and subsequently increase the speed to 5217 rpm at an angular acceleration of:

On the basis of this, a rotational moment of inertia for the shutter blade1in this Embodiment can be obtained as J=1×10−5kg/m2and the torque as:

Under such a condition, in the exposure-disabled period, the rotating motor2needs to operate for 30 ms. Based on a required length of the exposure-disabled period, the duration in which the shutter blade1does not rotate and stays still can be determined.

A method of using a shutter device for use in exposure by a photolithography machine in accordance with this Embodiment includes the steps as detailed below.

In S1, a shutter blade1, a rotating motor2, a controller and a supporter3are assembled. The shutter blade1includes a rotation center11and, disposed in correspondence with the rotation center11, at least one open portion12and at least one shielding portion13. The shielding portion13may have an inner hollow portion131and an outer scanning light shielding portion132that is concentric with the inner hollow portion with respect to the rotation center11. The hollow portion131may be fan-shaped and can effectively reduce the mass of the shutter blade1, which facilitates the control over the rotation of the shutter blade1and hence improves the exposure dose control accuracy.

In S2, the rotating motor2is activated under the control of the controller, causing the shutter blade1to rotate, thereby enabling and disabling exposure. Preferably, during the enabling and disabling of exposure subsequent to the activation of the rotating motor2under the control of the controller, the shutter blade1is caused to experience acceleration-constant speed-deceleration-constant speed-acceleration cycles, as shown inFIG. 9. Preferably, in each cycle, the constant speed at which the rotating motor2rotates subsequent to the acceleration is greater than or equal to 10 times the constant speed at which the rotating motor2rotates subsequent to the deceleration. This rotation speed variation arrangement is suitable for applications in which long exposure periods and short shutter closure periods are required. Due to a short shutter closure period, this scheme requires a high rate of utilization of light source illuminance. In addition, activation of the rotating motor2tends to be accompanied with an extremely high current which may lead to greater heat accumulation within the rotating motor2and hence structural expansion thereof and may cause the rotating motor2to be stuck or to experience a short circuit. In contrast, as the rotating motor2that drives the shutter blade1is always moving in this Embodiment without being frequently activated, its reliability and service lift are increased.

In summary, in the shutter device for use in exposure by photolithography machine and the method of using the shutter device, a shutter blade1includes a rotation center11and, disposed in correspondence with the rotation center, at least one open portion12and at least one shielding portion13, the rotation center11coupled to a rotating motor2. The rotating motor2drives the shutter blade1to rotate so that the shutter is opened and closed to enable and disable exposure. In addition, the shielding portion13includes a hollow portion131which significantly reduces the mass of the shutter blade1, facilitating the control over the rotation of the shutter blade1and improving the exposure dose control accuracy. Further, under the control of the controller, the opening and closing of the shutter is accomplished during rotation of the shutter blade1at a constant speed, while the acceleration and deceleration of the shutter blade1take place in the period when the shutter is in a closed state, which is relatively long and allows a large stroke. This significantly reduces the required torque of the rotating motor2. At the same time, as the constant speed of the rotating motor2is relatively high, the shutter opening and closing time is effectively shortened, resulting in a further improvement in the exposure dose control accuracy and in the performance of the photolithography machine.

Although a few embodiments of the present invention have been described herein, these embodiments are merely illustrative and are not intended to be construed as limiting the scope of the invention. Various omissions, substitutions and changes made without departing from the spirit of the invention are all intended to be included within the scope thereof.