KR102544732B1 - Substrate warpage measurement system using electrical signal supply and method thereof - Google Patents

Abstract

The present embodiments provide a system and method for measuring warpage of a substrate capable of measuring the state of a substrate located in a substrate holder by applying an electrical signal to an electrostatic chuck located in a chamber and using a change in impedance according to the path of the electrical signal. do.

Description

Board warpage measurement system and method using electrical signal application {SUBSTRATE WARPAGE MEASUREMENT SYSTEM USING ELECTRICAL SIGNAL SUPPLY AND METHOD THEREOF}

The technical field to which the present invention belongs relates to a system and method for measuring warpage of a substrate.

The contents described in this part merely provide background information on the present embodiment and do not constitute prior art.

Devices such as semiconductors, displays, and solar cells are manufactured through numerous processes. An unprocessed pure wafer is provided as the first substrate, but as the process is performed, multi-layered films and various patterns are formed on the wafer. A substrate warpage phenomenon occurs due to a difference in stress between each formed film and pattern. If the substrate warpage occurs, an error different from the desired result occurs during the process, and it becomes a continuous defect factor in the subsequent process.

Existing board warpage detection methods typically include a method for measuring stress in a board through a stress gauge and a method for measuring the degree of warpage through various optical measurements.

The method of measuring substrate stress through a stress gauge requires an additional process separate from the general process flow, so the process time is delayed due to the measurement time and substrate transfer, and since the substrate must be discarded after measurement, it plays a role in preventing substrate warpage in the actual process. cannot perform

The optical measurement method can determine the degree of warpage of the substrate between processes, but has a disadvantage in that fine process adjustment is impossible because the wafer warpage cannot be measured in real time during the process.

Korean Registered Patent Publication No. 10-1843473 (2018.03.23)

The main object of the present invention is to apply an electric signal to an electrostatic chuck located in a chamber and measure a warp state of a substrate positioned in a substrate holder by using a change in impedance according to a path of the electric signal.

Other non-specified objects of the present invention may be additionally considered within the scope that can be easily inferred from the following detailed description and effects thereof.

According to one aspect of the present embodiment, in a substrate warpage measurement system, a substrate holder including a chamber, a first electrode positioned at an upper end of the chamber, a second electrode positioned at a lower end of the chamber, and an electrostatic chuck; An electrostatic chuck power supply connected to the electrostatic chuck and supplying power to the electrostatic chuck, and an electrostatic chuck power supply connected to the electrostatic chuck, applying an electric signal to the electrostatic chuck, and using a change in impedance according to the path of the electric signal to the substrate. Provided is a system for measuring warpage of a substrate including a warpage measuring device for measuring a state of a substrate positioned in a holder.

The substrate warpage measurement system includes a first gas distributor formed on the first electrode and supplying gas to the inside of the chamber, and a first gas distributor connected to the first gas distributor and supplying the gas to the first gas distributor. A gas supply may be included.

The system for measuring the warpage of the substrate includes a second gas distributor formed on the second electrode and supplying gas to the substrate positioned in the substrate holder, and connected to the second gas distributor to supply the gas to the second gas distributor It may include a second gas supply to.

The system for measuring the warpage of the substrate may include a first impedance matching unit connected to the first electrode to control phases of voltage and current, and a first power supply connected to the first impedance matching device to supply power. there is.

The system for measuring the warpage of the substrate may include a second impedance matching unit connected to the second electrode to control phases of voltage and current, and a second power supply connected to the second impedance matching device to supply power. there is.

The system for measuring warpage of the substrate may include a vacuum device for adjusting the internal pressure of the chamber.

The warpage measurement device may include a filter connected to the electrostatic chuck and the warpage measurement device to filter the electric signal.

The warpage measuring device may determine whether or not the substrate is warped by applying an electrical signal based on a single frequency.

The warpage measurement device may determine the warpage shape of the substrate by applying an electrical signal based on a dual frequency.

The warpage measuring device is (i) a first type corresponding to a shape that is convexly bent upward, (ii) a second type corresponding to a shape that is convexly bent downward, (iii) some of which are convex above and others that are downward. It can be divided into a third type corresponding to a convexly curved shape.

The warpage measuring device compares a change in impedance according to (i) the load of the substrate, (ii) the load of the process area of the chamber, and (iii) the load of the space between the substrate and the substrate holder with a table stored in advance to determine the The warp shape of the board can be distinguished.

According to another aspect of the present embodiment, in a method for measuring warpage of a substrate, applying an electrical signal to an electrostatic chuck located in a chamber, and using a change in impedance according to a path of the electrical signal, the substrate located in the substrate holder It provides a method for measuring the warpage of a substrate comprising the step of measuring the state of.

As described above, according to embodiments of the present invention, an electric signal is applied to an electrostatic chuck located in a chamber, and the warp state of a substrate located in a substrate holder can be measured using a change in impedance according to a path of the electric signal. There is an effect.

Even if the effects are not explicitly mentioned here, the effects described in the following specification expected by the technical features of the present invention and their provisional effects are treated as described in the specification of the present invention.

1 is a diagram illustrating a system for measuring warpage of a substrate according to an embodiment of the present invention.
2 is a diagram illustrating a warpage measurement device of a substrate warpage measurement system according to an embodiment of the present invention.
3 is a diagram illustrating a warpage shape of a substrate measured by a system for measuring warpage of a substrate according to an embodiment of the present invention.
4 is a diagram illustrating a path of an electrical signal applied by a warpage measurement device of a substrate warpage measurement system according to an embodiment of the present invention.
5 is a diagram illustrating a substrate measured by a system for measuring warpage of a substrate according to an embodiment of the present invention.
6 is a flowchart illustrating a method for measuring warpage of a substrate according to another embodiment of the present invention.

Hereinafter, in the description of the present invention, if it is determined that a related known function may unnecessarily obscure the subject matter of the present invention as an obvious matter to those skilled in the art, the detailed description thereof will be omitted, and some embodiments of the present invention will be described. It will be described in detail through exemplary drawings.

This embodiment relates to a warpage measurement device connected to an electro-static chuck (ESC), and determines substrate warpage. By applying an additional electric measurement signal (Additional Electric Measurement Signal) to the DC voltage applied to the electrostatic chuck and detecting the change in the electrical measurement signal according to the presence and degree of warpage of the board, it detects the warpage of the board that occurs during or before and after the process. phenomena can be identified.

Equipment used during device manufacturing, such as semiconductors, displays, and solar cells, uses an electro-static chuck (ESC) to fix the substrate in a desired position during the process and to adjust process conditions such as temperature for desired process results. do. At this time, in order to produce optimal results without errors, it is required to measure the wafer warpage that may occur during the process in real time and eliminate the wafer warpage through fine process control based on this measurement. However, existing measuring devices have disadvantages in that a separate additional process is required or real-time process measurement is not possible.

In this embodiment, only measuring equipment for applying additional electrical signals is added without expensive equipment remodeling, and the presence and degree of substrate warpage are measured in real time during the process by detecting changes in additional electrical signals according to the presence and degree of substrate warpage. . Examples of processes that can be used include processes using plasma, such as sputtering, plasma enhanced chemical vapor deposition (PECVD), ion implantation, etching, and ashing. It includes processes that do not use plasma, such as CVD (Chemical Vapor Deposition) and evaporation processes.

The additional electrical measurement signal applied at this time is very small compared to direct current (DC) power applied to the electrostatic chuck or plasma power that can be applied during the process, and a frequency not normally used in the process can be selectively used, It is possible to measure easily separated from other power sources without affecting them.

1 is a diagram illustrating a system for measuring warpage of a substrate according to an embodiment of the present invention.

In this embodiment, a wafer warpage detection system is added to an electrostatic chuck used in a process of manufacturing devices such as semiconductors, displays, and solar cells, so that an additional electric measurement signal is applied when DC power is applied or in a standby state. By doing so, the existence and degree of warpage of the board are determined. For example, it is connected to an electrostatic chuck used in etching, deposition, ashing, etc. The electrostatic chuck is a monopole electrostatic chuck (Monopole ESC), a bi-pole electrostatic chuck (ESC), or a multi-channel electrostatic chuck (Multi-channel ESC). channel ESC) and the like.

The entire system of this embodiment is a type that can be used in a chuck capable of chucking a substrate using static electricity, including a monopole electrostatic chuck, a dipole electrostatic chuck, or a multi-channel electrostatic chuck.

Application of an additional electrical measurement signal for determining the presence and degree of warpage of the substrate may be performed in a different connection method according to conditions such as the type of electrostatic chuck or the type of process. The additional electrical measurement signal uses a total of two signal lines, one of which is connected to the electrostatic chuck electrode and the other to the other electrostatic chuck electrode or the process chamber wall (process chamber wall) according to the connection method. It can be connected and used.

Processes to which the substrate warpage measurement system 100 can be applied include plasma enhanced chemical vapor deposition (PECVD) processes, etching processes, and ashing processes, and plasma processes such as CVD (chemical vapor deposition). There are processes that do not use .

The substrate warpage measurement system 100 includes a process system and a warpage measurement device 170 . The process system includes a chamber 110, a substrate holder 140 to which a substrate 150 is attached, and the like.

The substrate 150 includes a semiconductor substrate, a wafer, a flat panel display substrate, a solar cell substrate, and the like. The process system may be configured to easily generate plasma in the process region 111 near the surface of the substrate 150 or to easily cause a chemical reaction. The processing system may be configured to process substrates of any size, such as 200 mm substrates, 300 mm substrates, or larger or smaller substrates.

The process system may include a first electrode 140 . The first power supply 143 may supply power to the first electrode 140 through the first impedance matching unit 144 . Power supplied to the first electrode 140 may be used to induce plasma generation in the process region 111 .

An ionized gas or process gas may be supplied through a gas injection device or the like. The gas injection device includes a gas distributor and a gas supplier. The gas distributor includes a first gas distributor 121 and a second gas distributor 131 , and the gas supplier includes a first gas supplier 122 and a second gas supplier 132 . In order to control the flow of a given process gas, the process system adjusts and controls the pressure through the vacuum device 180 .

The first gas distributor 141 is used to supply single or mixed gases to the process zone 111 of the process system. The first gas distributor 141 may receive a single or mixed gas required for a process from the first gas supplier 142 . The first gas distributor 141 may include a showerhead design. Alternatively, the first gas distributor 141 may include a center-edge distribution or multi-zone showerhead design. Through such a system, the flow or composition of a process gas in a region around the substrate 150 may be controlled.

Substrate 150 is attached to substrate holder 140 via electrostatic chuck 160 . The electrostatic chuck 160 is implemented by a monopole electro-static chuck, a multi-channel electro-static chuck, etc., in addition to the bipole electro-static chuck shown in FIG. 1. It can be.

The electrostatic chuck 160 may receive power from the electrode 130 through the electrostatic chuck power supply 135 to generate electrostatic power to clamp the substrate. The electrostatic chuck power supply 135 may supply DC power and the electrostatic chuck 160 may generate electrostatic power using the DC power.

The substrate holder 140 may include a heating system (not shown) or a cooling system (not shown) configured to adjust/control the temperature of the substrate holder 140 and the substrate 150 . In order to improve thermal conduction between the substrate 150 and the substrate holder 140 , a gas for heat transfer may be injected into the rear surface of the substrate through the second gas distributor 131 .

The substrate holder 140 may include the second electrode 130 , through which RF power or the like may be transmitted to the process region 111 to generate plasma. The substrate holder 140 may form and maintain plasma by supplying RF power from the second power supply 133 to the second electrode 130 through the second impedance matching unit 134 . In this configuration, the system can be used as a reactive ion etching (RIE) reactor or the like.

The process system includes a warpage measuring device 170 for measuring the presence and degree of substrate warpage. The warpage measurement device 170 lowers an additional electrical signal and measures a change in the signal. The warpage measuring device 170 is connected between the electrostatic chuck power supply 135 and the second electrode 130 through an electrical filter 171 .

The electrical filter 171 includes a low pass filter, a high pass filter, a band pass filter, and a band cut filter to block signals other than the additional electrical signal. etc. can be implemented. The warpage measuring device 170 may be connected to the wall of the chamber 110 in addition to the second electrode 130 .

As a signal transmission method in the warpage measuring device 170, a single-ended signal method or a double-ended signal may be applied.

2 is a diagram illustrating a warpage measurement device of a substrate warpage measurement system according to an embodiment of the present invention.

As a system configuration for measuring the warpage measuring device 170 and the filter 171, the warpage measuring device 170 includes an electrical signal power supply 210, an electrical signal measuring unit 220, and a reference load 230.

Warpage measuring device 170 is connected to filter 240 . The additional electrical signal supplied from the electrical signal power supply 210 passes through the filter 240 and is divided into a signal flowing to the measurement load 250 and a signal flowing to the reference load 230 . At this time, the measurement load 250 includes a substrate 150 to be measured in FIG. 1 and a substrate holder (130).

When the impedance value of the measurement load 230 changes according to the presence and degree of warpage of the board, the ratio of the additional electrical signal distributed to the measurement load 230 and the additional electrical signal distributed to the reference load 230 changes do. At this time, the changed ratio can be confirmed by measuring an additional electrical signal flowing to the reference load 230 using the electrical signal measuring unit 220 .

Electrical signal power supply 210 uses a signal that includes dual frequencies. The shape of the signal may be sinusoids or pulse waves. At this time, the given signal has two or more frequencies, and the electric signal measuring unit 220 analyzes the measured values for two or more different frequencies to infer the warped shape of the wafer. Since the warpage of the wafer is measured using only a single electrode or two electrodes, the dual-frequency measurement method has the advantage of being able to predict the approximate warpage shape, unlike the single-frequency method that only checks the warpage of the wafer.

Figure 3 illustrates the shape of the warp of the substrate measured by the system for measuring the warpage of the substrate according to an embodiment of the present invention, the presence and type of warp of the substrate, the substrate holder, the substrate, and the additional electrical signal supplied from the electrical signal power supply. represents the flow.

Fig. 3(a) shows a normal flat shape of the substrate, Fig. 3(b) shows a first type corresponding to an upwardly convexly curved shape, and Fig. 3(c) shows a downwardly convexly curved shape. The corresponding second type is shown, and FIG. 3(d) shows a third type corresponding to a shape in which some are convex on the top and others are convex on the bottom.

The measurement load 250 of FIG. 2 has a different impedance on a path through which an additional electric signal flows depending on whether or not the substrate is bent and the type of the substrate shown in FIG. 3 . The impedance of the measurement load 250 varies depending on whether or not the substrate is warped and the type, and the ratio of additional electrical signals distributed between the reference load 230 and the measurement load 250 varies. Through this, it is possible to measure the presence and degree of warpage of the substrate 150 in the process system.

Figure 4 illustrates the path of the electrical signal applied by the warpage measurement device of the substrate warpage measurement system according to an embodiment of the present invention, and the path of the additional electrical signal flowing through the substrate and the substrate holder in Figure 3 is an equivalent circuit it is shown

Referring to (a) of FIG. 4, the additional electrical signal starts from the warpage measurement device and filter 300, passes through the electrostatic chuck electrode (second electrode, 310), passes through the substrate load 320, and passes through the process on the top of the substrate. It passes through the area load 330, passes through the substrate load 735 again, passes through the electrostatic chuck electrode 315, and flows back to the warpage measuring device and filter 300.

Referring to (b) of FIG. 4, the measurement load changes depending on whether or not the substrate is warped, and the change at this time can be explained by the following reasons. Depending on the degree of warpage of the board, the distance through which the additional electric signal passes through the board changes, so that the board loads 420 and 425 may vary. Depending on the degree of warpage of the substrate, the distance through which the additional electric signal flows through the process area changes, and thus the process area load 430 may vary. Additional space loads 440 and 445 may occur between the substrate holder and the substrate due to a space generated according to the degree of bending of the substrate. Due to this change, the impedance value of the measured load represented by the sum of the substrate loads 420 and 425, the process area load 430, and the additional space loads 440 and 445 changes.

Accordingly, the ratio of the additional electrical signal distributed to the measurement load and the reference load is changed by the change in the measurement load, and the presence and degree of warpage of the board can be determined by measuring it with the electrical signal measuring unit.

5 is a diagram illustrating a substrate measured by a system for measuring warpage of a substrate according to an embodiment of the present invention.

The board warpage measurement system may apply an electrical signal based on a dual frequency and distinguish a warpage shape of the board. (i) the load of the substrate, (ii) the load of the process area of the chamber, and (iii) the load of the space between the substrate and the substrate holder. The change in impedance according to the load is compared with a pre-stored table to distinguish the warp shape of the substrate.

Exemplary tables are represented as Table 1 (Semiconductor wafer) and Table 2 (FTO Glass).

Exemplary experimental conditions for generating the table are as follows. Data other than voltage are measured through an impedance analyzer.

Insert the spacer between substrate to ESC

The spacer materials: glass fiber

Purpose of insert the spacer: reproduce wafer warpage

Spacer thickness: 0.25 mm / 0.5 mm

Spacer position order:

④: Reproduce edge bending (1 point)

②: Reproduce edge bending (1 point)

③+④: Reproduce edge bending (2 points)

④+⑤: Reproduce edge bending (2 points)

③: Reproduction of center bending

6 is a flowchart illustrating a method for measuring warpage of a substrate according to another embodiment of the present invention. The substrate warpage measurement method may be performed by a substrate warpage measurement system.

A method for measuring warpage of a substrate includes applying an electrical signal to an electrostatic chuck located in a chamber (S10), and measuring a state of a substrate located in a substrate holder using a change in impedance according to a path of the electrical signal (S20). ).

In the step of applying the electrical signal ( S10 ), the electrical signal based on the dual frequency is applied, and in the step of measuring the state of the board ( S20 ), the warped shape of the board can be distinguished.

The step of measuring the state of the substrate (S20) includes (i) a first type corresponding to an upwardly curved shape, (ii) a second type corresponding to a downwardly convexly curved shape, (iii) some of which are upwardly convex Some of them can be classified as a third type corresponding to a shape that is convexly curved at the bottom.

The step of measuring the state of the substrate (S20) compares a change in impedance according to (i) the load of the substrate, (ii) the load of the process area of the chamber, and (iii) the load of the space between the substrate and the substrate holder with a table stored in advance. Thus, the warp shape of the board can be distinguished.

These embodiments are for explaining the technical idea of this embodiment, and the scope of the technical idea of this embodiment is not limited by these embodiments. The scope of protection of this embodiment should be construed according to the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of rights of this embodiment.

Claims (15)

In the board warpage measurement system,
chamber;
a first electrode positioned at an inner upper end of the chamber;
a substrate holder positioned at an inner lower end of the chamber and including a second electrode and an electrostatic chuck;
an electrostatic chuck power supply connected to the electrostatic chuck and supplying power to the electrostatic chuck; and
A warpage measuring device connected to the electrostatic chuck, applying an electric signal to the electrostatic chuck, and measuring a state of a substrate positioned in the substrate holder by using a change in impedance according to a path of the electric signal,
The warpage measuring device compares a change in impedance according to (i) the load of the substrate, (ii) the load of the process area of the chamber, and (iii) the load of the space between the substrate and the substrate holder with a table stored in advance to determine the A warpage measurement system of a substrate, characterized in that for distinguishing the warpage shape of the substrate. According to claim 1,
a first gas distributor formed on the first electrode to supply gas into the chamber; and
and a first gas supplier connected to the first gas distributor to supply the gas to the first gas distributor. According to claim 1,
a second gas distributor formed on the second electrode to supply gas to the substrate positioned in the substrate holder; and
and a second gas supplier connected to the second gas distributor to supply the gas to the second gas distributor. According to claim 1,
a first impedance matching unit connected to the first electrode to control phases of voltage and current; and
A system for measuring warpage of a substrate, characterized in that it comprises a first power supply connected to the first impedance matching device to supply power. According to claim 1,
a second impedance matching unit connected to the second electrode to control phases of voltage and current; and
A system for measuring warpage of a substrate, characterized in that it comprises a second power supply connected to the second impedance matching device to supply power. According to claim 1,
The warpage measurement system of the substrate, characterized in that it comprises a vacuum device for adjusting the internal pressure of the chamber. According to claim 1,
The system for measuring warpage of a substrate, characterized in that the warpage measuring device includes a filter connected to the electrostatic chuck and the warpage measuring device to filter the electrical signal. According to claim 1,
The warpage measurement system of the substrate, characterized in that for determining the presence or absence of warpage of the substrate by applying an electrical signal based on a single frequency. delete According to claim 1,
The warpage measuring device is (i) a first type corresponding to a shape that is convexly bent upward, (ii) a second type corresponding to a shape that is convexly bent downward, (iii) some of which are convex above and others that are downward. A warpage measuring system of a substrate, characterized in that divided into a third type corresponding to a convexly bent shape. delete In the method of measuring the warpage of the substrate,
applying an electrical signal to an electrostatic chuck located in the chamber; and
Measuring a state of a substrate located in a substrate holder using a change in impedance according to the path of the electrical signal,
The step of measuring the state of the substrate may include (i) the load of the substrate, (ii) the load of the process area of the chamber, and (iii) the change in impedance according to the load of the space between the substrate and the substrate holder in a pre-stored table. A method for measuring warpage of a substrate, characterized in that for distinguishing the warpage shape of the substrate compared to. delete According to claim 12,
The step of measuring the state of the substrate is (i) a first type corresponding to an upwardly convex curved shape, (ii) a second type corresponding to a downwardly convexly curved shape, (iii) some other upwardly convexly curved shapes A method for measuring warpage of a substrate, characterized in that some are divided into a third type corresponding to a shape that is convexly bent below. delete

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