JP3792043B2 - Nozzle device and substrate polishing apparatus using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nozzle device used in a gas polishing apparatus. Here, gas polishing is a method in which corrosive gas is locally sprayed onto the surface of a substrate such as a semiconductor wafer to remove unevenness and flatten it, or conversely, predetermined unevenness is formed on the surface. is there.
[0002]
[Prior art]
In recent years, as semiconductor devices are highly integrated, circuit wiring is becoming finer and the distance between wirings is becoming narrower. Along with this, the depth of focus when forming a circuit by optical lithography or the like becomes shallow, so that a higher flatness of the imaging surface of the stepper is required.
[0003]
As means for flattening the surface of the semiconductor wafer, the polishing table includes a polishing table having a polishing surface, and a holding member that holds the material to be polished against the polishing table and presses the polishing surface. A chemical-mechanical polishing method (CMP) is known in which polishing is performed while supplying a predetermined polishing liquid corresponding to the material of the surface to be polished.
[0004]
[Problems to be solved by the invention]
However, since this chemical / mechanical polishing method flattens the substrate while polishing it over the entire surface, it is not suitable for flattening the macro unevenness on the substrate. Cost.
[0005]
An object of the present invention is to provide a polishing apparatus capable of more efficiently planarizing a substrate surface in place of or in combination with a conventional chemical / mechanical polishing method.
[0006]
[Means for Solving the Problems]
A nozzle device according to the present invention is disposed opposite to a processing surface of a substrate, and a plurality of nozzles are dispersed at predetermined intervals in a nozzle device that performs gas polishing by spraying corrosive gas from the nozzle onto the processing surface. a nozzle assembly disposed in the flow of the gas from the nozzles have a control mechanism for individually controlling, wherein the nozzle assembly, the nozzle position adjusting mechanism for adjusting the spacing of the nozzle a nozzle device which is characterized that you have is provided.
[0007]
In the nozzle device having such a configuration, for example, a substrate is placed in a chamber adjusted to a predetermined degree of vacuum, and a necessary polishing amount at a corresponding position is obtained from each of the plurality of nozzles toward the processing surface. Gas is injected while controlling pressure, flow rate, flow rate, polishing time, and the like. Thereby, the predetermined range of a to-be-processed surface can be polished in one process.
[0008]
The required amount of polishing at each position is calculated based on the uneven distribution on the surface of the substrate measured in advance. Further, a remote sensor may be provided at the tip of each nozzle, and the gas injection amount may be controlled while measuring the uneven distribution and calculating the necessary polish amount in real time.
[0009]
It is preferable to polish each nozzle as locally as possible so as to enhance the shaping function of the surface to be processed, and the nozzle can have a shape and a diameter suitable for the purpose. For example, an exhaust port may be opened in the vicinity of the nozzle so that the gas from each nozzle does not affect other regions. For the same purpose, the nozzles may be opened and closed intermittently to inject gas as pulses, thereby improving the controllability of the gas injection amount.
[0010]
You may make it arrange | position the said nozzle in the area | region corresponding to the whole surface of the said to-be-processed surface. Thereby, the whole surface to be processed can be polished in one step. Moreover, you may make it arrange | position the said nozzle in the area | region corresponding to the shape which divided | segmented the said to-be-processed surface. Thereby, the whole surface to be processed can be polished in several steps corresponding to the number of divisions.
[0011]
The control mechanism includes an opening and closing valve for individually opening and closing the air supply pipe to supply the to each nozzle, wherein the opening and closing valve is characterized in that it is arranged integrally with the nozzle assembly . Thereby, the influence of the gas remaining between the on-off valve and the nozzle tip can be reduced, and the control accuracy can be improved.
[0012]
Further, the nozzle assembly is characterized in that the nozzle position adjusting mechanism for adjusting the spacing of the nozzles is provided. Thus, the nozzle interval is adjusted according to the size of the target substrate, the polishing conditions, the purpose, etc., and the polishing can be performed under more suitable conditions.
[0013]
Further, when the distance D of the adjacent nozzles is, that the half width of the polished shapes in a given amount of polish that each nozzle is carried out alone was d, 0.9d / 1.177 <D ≦ 1.1d / and it is characterized in that it is set to 1.177. Thereby, since the shape after polishing by a plurality of nozzles has a flat bottom portion, a wide range can be efficiently flattened.
[0014]
The nozzle interval D may be set to D <d / 1.177, where d is the half width of the polished shape in a predetermined amount of polishing performed independently by each nozzle. In this case, since the shape after polishing by a plurality of nozzles becomes deeper and larger than that of a single nozzle, the setting of D <d / 1.177 is used when removing larger irregularities. In addition, since a larger polishing shape can be obtained, if the distance D ′ and the half-value width d ′ of the large polishing shape are D ′ = d ′ / 1.177 (± 10%), the larger polishing range can be obtained. Polishing deeply and flattening the bottom.
[0015]
It is good also as a planar arrangement | positioning which positions each nozzle at the vertex of an equilateral triangle. Thereby, the nozzles can be arranged so that the intervals between the adjacent nozzles are all equal, and the planarization can be performed efficiently.
[0016]
The control mechanism may include an open / close valve that individually opens and closes an air supply pipe that supplies air to the nozzles, and the open / close valve may be disposed close to the nozzle assembly. As a result, the space between the on-off valve and the nozzle tip can be reduced, the time lag between the opening and closing of the valve and the gas flow can be reduced, and the control accuracy can be improved.
[0017]
The polishing apparatus of the substrate of the present invention is characterized in that the nozzle device described above, and the chemical mechanical polishing devices are juxtaposed. As a result, the processed surface of the substrate is first locally gas-polished to remove or easily remove the macro unevenness on the substrate, and then the micro unevenness is removed by a chemical / mechanical polishing apparatus. Thus, polishing with high flatness can be performed efficiently.
[0018]
Further, the gas polishing method of the present invention includes a nozzle arrangement step of arranging a plurality of nozzles facing a processing surface of a substrate, a corrosive gas from the nozzles intermittently flowing in a predetermined amount of pulses, and And a polishing step of spraying the work surface while controlling the gas flow from each nozzle by adjusting the number of pulses. In the nozzle placement step, each nozzle has an interval D between each nozzle. the half width of the polished shapes in a given amount of polish when the d, is characterized in that setting to 0.9d / 1.177 <D ≦ 1.1d / 1.177.
[0019]
Further, the gas polishing process using the nozzle device described above , or the gas polishing process described above and the chemical / mechanical polishing process may be sequentially performed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. First, the outline of the gas polishing apparatus will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, this gas polishing apparatus is connected to four airtight chambers that can be evacuated, that is, a central robot chamber 10 and gates 12, 14, 16 to the robot chamber 10. The substrate storage chamber 18, the film thickness measurement chamber 20, the polishing chamber 22, a device associated with these chambers, and a control device 24 that controls the whole. In the film thickness measuring chamber 20, for example, a remote sensor that measures the distance to the substrate W surface in a non-contact manner, a sensor of a film thickness measuring device using eddy current, or a sensor of a film thickness measuring device using an ellipsometer is scanned along the substrate surface. Thus, a film thickness measuring device 26 is provided for obtaining the unevenness state of the substrate surface as numerical data.
[0021]
As shown in FIG. 2, the polishing chamber 22 is provided with a holding table 28 for placing the substrate W on the center thereof, which is a heater 30 for maintaining the substrate W at a predetermined polishing temperature and rotates the substrate by a predetermined angle. And a rotating device 32. At a predetermined position above the holding table 28, a nozzle assembly 38 supported by an outdoor lifting / lowering device 36 via a support shaft 34 is provided. The sensor 48 that detects the degree of vacuum in the polishing chamber 22 includes a vacuum pump 40 that exhausts the polishing chamber to a predetermined degree of vacuum, an exhaust path 44 that has a detoxifying device 42 that removes harmful components in the exhaust gas, and a necessary amount. Accordingly, a purge gas supply path 46 for supplying a purge gas is provided. Further, a sensor 48 for detecting the degree of vacuum in the room, a substrate temperature sensor (not shown), and the like are provided.
[0022]
The nozzle assembly 38 is configured such that a plurality of nozzles 50 are attached to the nozzle board 52 so as to penetrate the nozzle assembly 52, and a flexible gas supply pipe 54 that supplies corrosive gas is connected to each nozzle 50. . The supply pipe 54 is bundled and introduced outside the polishing chamber, and is connected to a gas supply device 56. In this example, the nozzle assembly 38 has a shape covering one-sixth of the surface of the substrate W. As shown in FIG. 4, a nozzle-shaped nozzle board 52 having a central angle of 60 degrees has a predetermined diameter. The pipe-shaped nozzles 50 are distributed and arranged so as to be positioned at the apexes of the equilateral triangle so that the distances between adjacent nozzles are equal.
[0023]
In this example, the gas supply device 56 uses a mixture of a corrosive gas 58 such as ClF ₃ and an inert gas 60 such as Ar, and the gas sources 58 and 60 are supplied with respective supplies. A supply pipe 68 having a filter 62, a flow rate controller (MFC) 64, and an electromagnetic opening / closing valve 66 is provided for each pipe 54 and connected to each supply pipe 54. The MFC 64 and the opening / closing valve 66 of each supply pipe 68 are respectively connected to the control output terminal of the control device 24, and the flow rate of each gas and the opening / closing timing are controlled by the control device.
[0024]
The control device 24 intermittently opens the electromagnetic on-off valve 66 to supply the polishing gas as pulses rather than continuously. As a result, the surface of the substrate W on which the supplied gas is jetted is instantaneously polished and then diffused instantaneously, thereby performing local polishing and facilitating control of the gas supply amount that affects the polishing amount. ing. Of course, the gas may be continuously supplied.
[0025]
The interval D of the nozzles 50 in the nozzle assembly 38 is formed by a single nozzle as shown in FIG. 5, that is, a half width of a polished shape in a predetermined amount of polishing performed by each nozzle 50 alone. Assuming that the width at a half position of the depth H ₀ of the concave portion R is d, it is set equal to D = 2σ = d / 1.117. The shape of the recess R has a normal distribution, and this σ corresponds to the standard deviation. The value of σ varies depending on various conditions for polishing. Here, the test was conducted under the following conditions.
[0026]
Workpiece: Polycrystalline silicon polish gas Composition: ClF ₃ : Ar = 1: 2
Nozzle diameter: 6.4 mm (inner diameter 4.8 mm)
Gas flow rate: 90cc
Polish time: 0.6sec
Workpiece temperature: 50 ° C
Polished maximum depth H ₀ : about 1000 mm
[0027]
The effect | action by such a structure is demonstrated with reference to FIG. FIG. 6 shows a change in the cross-sectional shape of the polishing surface when the nozzle interval is changed, and shows that the shape polished by the nozzle assembly 38 is obtained by superposing the polishing amount of each nozzle 50. ing.
[0028]
In this figure, when the nozzle interval D is smaller than 2σ, the concave portion R has a deeper profile as shown in FIGS. 9A to 9C, and the nozzle interval D is equal to 2σ as shown in FIG. In this case, when the cross section is a trapezoidal concave portion R and the nozzle interval D is larger than 2σ, a concave portion R having an uneven surface is formed as shown in FIG. Therefore, when polishing a portion of a certain area flatly,
δ = D / 2σ
Is preferably about 1.0. When δ is 1.0 or less, the shape after polishing by a plurality of nozzles becomes deeper and larger than that of a single nozzle. Therefore, when cutting larger irregularities, the setting of D <d / 1.177 is used. To do. Further, since larger unevenness can be obtained, if the distance D ′ and the half-value width d ′ of each large polishing shape are D ′ = d ′ / 1.177 (± 10%), a larger range is obtained. Polishing deeper and flattening the bottom.
[0029]
Next, a process for planarizing the substrate surface by the gas polishing apparatus configured as described above will be described. The substrate W to be polished is first transferred from the storage chamber 18 to the film thickness measuring chamber 20, where the film thickness measuring device 26 measures the film thickness over the entire surface of the substrate. Thereby, the film thickness distribution data is stored in the image processing unit 24 b of the control device 24.
[0030]
Based on the film thickness data, the control calculation unit 24a of the control device 24 determines which portion of the substrate W is to be polished in the polishing chamber 22. That is, in the case of flattening the substrate W, the nozzle 50 corresponding to the position of the corresponding portion is polished so as to polish the peak portion of the obtained film thickness map of the substrate W by an amount corresponding to the height. Parameters such as the flow rate, concentration, and time (number of pulses) of the gas to be passed are determined.
[0031]
In this embodiment, since the nozzle assembly 38 has a shape obtained by dividing the substrate surface into six parts, the substrate surface is also polished 6 times by 1/6. Accordingly, the parameters for each nozzle 50 are determined for each of the six polishing operations.
[0032]
Next, the substrate W is transferred to the polishing chamber 22 by the robot 10a, where gas polishing is performed according to the above-described parameters. First, after the polishing chamber 22 is set to a predetermined vacuum state and the substrate temperature is heated to a predetermined temperature by the heater 30, the first one-sixth portion of the surface of the substrate is polished as shown in FIG. This is performed by flowing a gas from the nozzle 50 along the line. The height of the nozzle assembly 38 is determined in advance based on the relationship between the polishing profile of each nozzle and the nozzle interval, and is adjusted by the lifting device 36.
[0033]
In this case, in this nozzle assembly, δ = 1.0 is set. For example, when gas is simultaneously injected from three adjacent nozzles 50, the cross section becomes a trapezoid as shown in FIG. Polishing is performed to form a concave portion R of such a profile. The planar shape and area of the flat portion are appropriately set by selecting the number of the injection nozzles 50. In this way, the unevenness can be accurately flattened by polishing by sequentially combining the concave portions R each having a flat portion whose shape and cross section can be adjusted. Next, the substrate W is rotated by 1/6 to perform gas polishing of this portion, and thereafter, the entire surface of the substrate W is similarly polished.
[0034]
And after performing a washing | cleaning and a drying process as needed, it returns to the film thickness measurement chamber 20 with the robot 10a, and a film thickness is measured again. Then, if the degree of unevenness of the substrate surface is outside the allowable reference range, re-polishing is performed, and if it is within the range, the substrate is returned to the storage chamber 18. After performing gas polishing, chemical / mechanical polishing (CMP) may be further performed to remove micro unevenness.
[0035]
In such a nozzle assembly 38, since the entire surface of the substrate is divided into six parts, the nozzle plate 52 can be made smaller than the case where it is formed in a size corresponding to the entire surface of the substrate. You may divide into the appropriate number. In this example, the nozzle assembly 38 is moved to the next processing surface by rotating the substrate W side. However, the nozzle assembly side may be moved. In this example, the nozzle board 52 is fan-shaped, but the shape of the division is appropriate, and the direction of relative movement may be linear movement in the XY direction instead of rotation. Further, the nozzle board 52 may be formed in a size corresponding to the entire surface of the substrate W, whereby the polishing operation on the entire surface can be performed at a time to improve the polishing work efficiency.
[0036]
FIG. 8 shows another embodiment of the present invention, in which each nozzle 50A is configured as a double pipe comprising an inner gas nozzle pipe 70 and an outer exhaust pipe 71. The exhaust pipe 71 of each nozzle 50A is gathered in a manifold (not shown), which is connected to an exhaust path having a vacuum pump. This exhaust path may be shared by the polishing chamber 22 or may be provided separately.
[0037]
In the collective nozzle 38 configured as described above, an exhaust pipe 71 is opened in the vicinity of the nozzle pipe 70, and the gas discharged from each nozzle is sucked and exhausted in the vicinity thereof. Therefore, the influence of the gas from one nozzle becomes more localized, so that the shape control of the surface is performed more precisely.
[0038]
9 and 10 show still another embodiment of the present invention, in which a gas distribution unit which is a part of the gas supply device 56 is incorporated in the nozzle assembly 38A. That is, the nozzle assembly 38A in this example includes a header 74 that stores a polishing gas of a predetermined pressure in a casing 72 that is integral with the nozzle board 52A, and the flow rate adjusting valve 76 and the on-off valve 66 that connect the header 74 and each nozzle 50 to each other. An air supply pipe 78 that communicates via the air is incorporated. Each of these valves is connected to an output terminal of the control device 24, and is controlled by the same method as in the previous embodiment to perform gas polishing.
[0039]
In the gas polishing apparatus having such a configuration, the opening / closing valve 66 for opening and closing the nozzle 50 is provided at a position closer to the tip of the nozzle 50, so that the gas present in the portion from the opening / closing valve 66 to the nozzle tip is the valve 66. It is possible to prevent a delay in control due to the flow after the closing of.
[0040]
FIG. 11 shows a nozzle assembly 38B according to another embodiment of the present invention, in which one fixed nozzle 50B is provided at the center of a disk-like nozzle board 52B, and 6 The movable nozzles 50 </ b> C are provided so as to be slidable in the radial direction through the sliding mechanism 80 at equal intervals. The sliding mechanism 80 of each movable nozzle 50C is provided with a motor 82 and a worm gear 84 that changes its rotation into a linear motion. In this example, six movable nozzles 50C are provided, but it is possible to increase the number of movable nozzles further outside. In this example, an actuator (motor) 82 is provided for each nozzle. However, a plurality of nozzles may be connected by a link mechanism and interlocked by a single actuator.
[0041]
In the nozzle assembly 38B having such a configuration, the nozzle interval D can be changed according to the polishing conditions. Accordingly, when the value of 2σ changes depending on various polishing conditions, the nozzle interval D is changed in accordance with the value and adjusted so that δ = 1.0. Further, not only when δ = 1.0, but also when it is better to form a recess having a sharp cross-sectional shape as shown in FIGS. 6A to 6C, D is reduced and δ <1. Used as 0.
[0042]
【The invention's effect】
As described above, according to the present invention, by injecting gas from each nozzle while controlling the pressure, flow velocity, flow rate, polishing time, etc., the predetermined range of the work surface can be set at each position in one step. It can be polished to obtain the required amount of polish. Moreover, the recessed part which has a required profile can be formed by setting a nozzle space | interval suitably and injecting gas, adjusting a flow from each nozzle. Therefore, the predetermined range of the surface to be processed can be polished so as to obtain the required polishing amount at each position, and the predetermined surface shape can be efficiently obtained. Therefore, in the semiconductor manufacturing process, the substrate surface can be more efficiently planarized by replacing or in combination with the conventional chemical / mechanical polishing method.
[Brief description of the drawings]
FIG. 1 is a plan view showing an overall configuration of a gas polishing apparatus in which a nozzle device of the present invention is used.
2 is a cross-sectional view showing the configuration of the gas polish chamber of FIG. 1. FIG.
FIG. 3 is a diagram illustrating a configuration of a nozzle device.
FIG. 4 is a diagram showing a structure of a nozzle assembly.
FIG. 5 is a diagram showing a cross-sectional shape after polishing by one nozzle.
FIG. 6 is a diagram showing a relationship between a nozzle interval and a cross-sectional shape of a polished surface.
FIG. 7 is a diagram showing the position of a nozzle when polishing a substrate.
FIG. 8 is a diagram showing another embodiment of the nozzle assembly.
FIG. 9 is a diagram showing another embodiment of the nozzle device.
10 is a diagram showing a nozzle device according to the embodiment of FIG. 9;
FIG. 11 is a diagram showing another embodiment of the structure of the nozzle assembly.
FIG. 12 is a diagram showing a polishing process by a conventional CMP method.
[Explanation of symbols]
24 Control device 38 Nozzle assembly 50 Nozzle 52 Nozzle board 58 Corrosive gas 64 Flow rate controller (MFC)
66 On-off valve 78 Air supply pipe 84 Nozzle position adjustment mechanism W Substrate

Claims (5)

In a nozzle device that is disposed to face a processing surface of a substrate and performs gas polishing by blowing a corrosive gas from the nozzle to the processing surface.
A nozzle assembly in which a plurality of nozzles are distributed at predetermined intervals; and
A control mechanism for individually controlling the flow of the gas from each nozzle,
The nozzle assembly is provided with a nozzle position adjusting mechanism for adjusting a nozzle interval.   2. The control mechanism according to claim 1, wherein the control mechanism includes an on-off valve that individually opens and closes an air supply pipe that supplies air to the nozzles, and the on-off valve is disposed integrally with the nozzle assembly. Nozzle device. When the interval D between the adjacent nozzles is d, the half width of the polished shape in a predetermined amount of polishing performed independently by each nozzle,
0.9d / 1.177 <D ≦ 1.1d / 1.177
The nozzle device according to claim 1, wherein the nozzle device is set as follows. A nozzle assembly that is disposed opposite to the processing surface of the substrate, and a plurality of nozzles that perform gas polishing by spraying corrosive gas from the nozzle to the processing surface, and are dispersed at predetermined intervals;
A control mechanism for individually controlling the flow of the gas from each nozzle,
The nozzle assembly is provided with a nozzle position adjusting mechanism for adjusting the nozzle interval;
A substrate polishing apparatus, which is provided with a chemical / mechanical polishing apparatus. A nozzle arrangement step of arranging a plurality of nozzles facing the processing surface of the substrate;
A polishing step of intermittently flowing a corrosive gas from the nozzle in a predetermined amount at a time, and blowing the gas to the work surface while controlling the gas flow from each nozzle by adjusting the number of pulses, and
In the nozzle arrangement step, when the interval D between the nozzles is d, the half width of the polished shape in a predetermined amount of polishing performed independently by each nozzle,
0.9d / 1.177 <D ≦ 1.1d / 1.177
A gas polishing method, characterized by being set to

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