JP4957820B2 - Liquid processing apparatus, liquid processing method, and storage medium - Google Patents

Description

  The present invention relates to a liquid processing apparatus, a liquid processing method, and a storage medium that perform a liquid processing by supplying a processing liquid to a substrate.

  In a photoresist process, which is one of semiconductor manufacturing processes, various chemical solutions are supplied to the surface of a semiconductor wafer (hereinafter referred to as a wafer) to perform liquid processing. As an apparatus for performing this liquid treatment, for example, there is a resist coating apparatus for applying a resist as a chemical solution to a wafer. The resist coating apparatus includes a nozzle that supplies a resist to the wafer, and the resist is pumped from the pump to the resist supply nozzle via a pipe.

  If the resist supply nozzle is not used for a long time in this resist coating apparatus, the resist is solidified in the pipe and clogging occurs, or the resist is foamed and air is collected in the pipe. As a result, the resist is not normally discharged from the resist supply nozzle, and there is a possibility that the processing varies from wafer to wafer. Therefore, the resist coating apparatus may be provided with detection means for optically detecting the discharge of the resist from the resist supply nozzle.

  As this detection means, for example, there is a CCD camera that images the liquid flow of the resist discharged from the resist supply nozzle, and a computer provided in the resist coating apparatus based on an image acquired by this CCD camera detects abnormalities in resist discharge. Is detected. As another detection means, there is a sensor including an irradiation unit that irradiates a surface of the wafer W with a laser and a light receiving unit that receives the laser reflected from the wafer W. When the resist is supplied to the wafer, the amount of light received by the light receiving section changes, and the computer detects an abnormality in the resist discharge based on the change in the amount of received light.

  However, the color varies depending on the resist, and if the transparency is high, it may be difficult to detect with the camera as described above. Further, the surface state of the wafer is various, and the light reflectance and reflection angle are different. Therefore, depending on the surface state, detection by the sensor may be difficult. In addition, various types of wafers may be carried into the resist coating apparatus, and processing may be performed using different resists for each wafer. In that case, it is difficult to set a threshold value for distinguishing whether or not the resist is discharged by the above-described methods. Under such circumstances, there has been a demand for a liquid processing apparatus that can determine the supply state of a chemical liquid such as a resist without depending on optical detection means.

  Patent Document 1 describes a liquid processing apparatus in which a strain gauge is provided outside a substrate, and a discharge pressure is measured by discharging a processing liquid from a discharge nozzle to the strain gauge. However, in the invention of Patent Document 1, if an abnormality occurs during discharge of the processing liquid onto the substrate, the abnormality cannot be detected. Patent Document 2 describes an ejection device in which a strain gauge is provided in a nozzle in order to detect distortion of the nozzle due to contact with opposing components. The detection circuit is based on a change in the resistance value of the strain gauge. Detects the amount of distortion. However, in the above-described resist coating apparatus, in the case where processing is continuously performed on a wafer, it is conceivable that processing is performed on the next wafer before the nozzle distortion caused by the resist discharge operation has completely returned. Therefore, it is difficult to set a threshold when detecting the presence or absence of ejection based on a change in the amount of distortion.

JP-A-8-17780 JP-A-2005-152826

  The present invention has been made under such circumstances, and an object of the present invention is to provide a technique that can reliably determine the supply state of a chemical solution in a liquid processing apparatus that performs a liquid process by supplying the chemical solution to a substrate. is there.

The liquid processing apparatus of the present invention is an apparatus for performing liquid processing by supplying a chemical solution from a pump through a pipe and a nozzle to a substrate held by a substrate holding unit.
A strain sensor provided with a strain gauge in the flow path component from the pipe to the tip of the nozzle;
A differentiating circuit for differentiating the output voltage of the strain sensor;
And a determination unit that determines the supply state of the chemical solution according to the output of the differentiating circuit.

The strain gauge is provided, for example, in a pipe made of resin or a nozzle made of resin. The strain sensor is configured such that, for example, when the strain gauge extends, the output voltage has one sign of positive and negative,
The determination unit may be configured to determine that the chemical solution has flowed when the output voltage of the differentiating circuit is the one sign and the absolute value is greater than a predetermined threshold value. .

  The determination unit determines that the flow of the chemical solution has stopped when the output voltage of the differentiating circuit has a sign opposite to the one sign and the absolute value is greater than a predetermined threshold value. It may be configured as follows. Further, for example, when the elapsed time after determining that the chemical liquid has flowed is shorter than a predetermined set time, the output voltage is a sign opposite to the one sign, and the absolute value is It is configured to determine that bubbles are included in the chemical liquid when the threshold value is larger than a predetermined threshold value.

The liquid processing method of the present invention includes a step of holding a substrate on a substrate holding portion,
A step of supplying a chemical solution from the pump to the substrate through a pipe and a nozzle to perform a liquid treatment;
Differentiating the output voltage of a strain sensor including a strain gauge provided in a flow path component from the pipe to the tip of the nozzle with a differentiation circuit;
Determining the supply state of the chemical solution according to the output of the differentiation circuit;
It is provided with.

The liquid processing method includes a step of outputting a voltage of one of positive and negative signs from the strain sensor when the strain gauge is extended,
A step of determining that the chemical solution has flowed when the output voltage of the differentiating circuit is the one of the signs and the absolute value is greater than a predetermined threshold;
May be provided. A step of determining that the flow of the chemical solution has stopped when the output voltage of the differentiating circuit has a sign opposite to the one sign and the absolute value is greater than a predetermined threshold value. Also good. Further, for example, when the elapsed time after determining that the chemical liquid has flowed is shorter than a predetermined set time, the output voltage is a sign opposite to the one sign, and the absolute value is a predetermined threshold. A step of determining that bubbles are included in the chemical solution when the value becomes larger than the value is included.

The storage medium of the present invention is a storage medium for storing a program used in a liquid processing apparatus that supplies a chemical solution from a pump via a pipe and a nozzle to a substrate held by a substrate holding unit.
The program has a group of steps so as to execute the above-described liquid processing method.

  According to the present invention, an output voltage of a strain sensor including a strain gauge provided in a chemical liquid flow path constituent member is differentiated by a differentiation circuit, and a supply state of the chemical liquid is determined according to an output of the differentiation circuit. Therefore, the influence of the surface state of the substrate and the optical properties of the chemical liquid can be suppressed as compared with the case where an optical detection means is used, so that the chemical liquid supply state can be determined with high accuracy.

It is a vertical side view of the resist coating apparatus according to the present invention. It is a perspective view of the resist coating apparatus. It is a block diagram of the circuit unit of the said resist coating apparatus. It is a graph which shows the change of the amount of distortion of piping. It is a table | surface figure which shows the relationship between the output from a differentiation circuit, the output from a comparison circuit, and the determination of a control part. It is a longitudinal cross-sectional view of piping. It is a graph which shows the change of the amount of distortion when a bubble passes piping. It is a block diagram of the control part provided in a resist coating device. It is a flowchart which shows the determination process by a control part. It is a graph which shows the result of a reference test. It is a graph which shows the result of a reference test.

(First embodiment)

  Next, the resist coating apparatus 1 which is an embodiment of the liquid processing apparatus of the present invention will be described. As shown in FIG. 1, the resist coating apparatus 1 is provided inside a housing 11. A fan filter device 13 that forms a clean downflow is provided in an upper portion of the internal space 12 of the housing 11.

  The resist coating apparatus 1 includes a spin chuck 21 that is a substrate holding unit. The spin chuck 21 holds the wafer W horizontally by vacuum suction, can be moved up and down via a shaft portion 23 by a lower drive unit 22, and is rotatable about a vertical axis.

  In addition, the resist coating apparatus 1 includes a cup (enclosing member) 3. The cup 3 surrounds the periphery of the wafer W held by the spin chuck 21 and has a liquid processing space 31 therein, and prevents the chemical liquid such as resist supplied to the wafer W from scattering. It is. Further, the cup 3 is provided with a liquid receiving portion 32 having a concave shape on the lower side, in a mode in which the outer periphery and the inner region are partitioned on the lower peripheral edge of the wafer W over the entire periphery. The bottom is provided with a waste liquid port 33 for discharging a drain of the stored coating liquid and the like, and two exhaust ports 34 and 35 are provided at the bottom of the inner region.

  A disc member 36 that guides the processing liquid to the outer region is provided inside the cup 3. The disk member 36 has a through-hole 37 through which the shaft portion 23 penetrates in the center, and a mountain-shaped guide portion 38 is provided at the periphery. Further, three elevating pins 39 are provided so as to penetrate the disc member 36, and the elevating pins 39 are raised and lowered by the elevating mechanism 30. The tip of the lift pin 39 abuts on the back surface of the wafer W, so that the wafer W is moved up and down, whereby the wafer W is inserted into and removed from the liquid processing space 31. The wafer W is transferred between the outside of the apparatus 1 and the lift pins 39 by the transfer means 14 shown in FIG.

  Further, the resist coating apparatus 1 includes a resist supply nozzle 41 and a solvent supply nozzle 51 as shown in FIG. The resist supply nozzle 41 is made of, for example, resin, and is connected to a resist supply system 43 through a pipe 42. The resist supply system 43 includes a storage unit that stores the resist and a pump that pumps the resist from the storage unit to the resist supply nozzle 41 and receives a control signal transmitted from the control unit 80 to supply the resist. Do. A valve 44 is provided in the pipe 42 to control the supply and disconnection of the resist to the wafer W. The pipe 42 is made of, for example, resin.

  The resist supply nozzle 41 is attached to the arm 45. An arm driving section 46 is provided for moving the resist supply nozzle 41 in the Z-axis direction (vertical direction) and the X-axis direction (horizontal direction) shown in FIG. In the figure, reference numeral 47 denotes a guide rail, which guides the arm drive unit 46 and an arm drive unit 56 described later in the X-axis direction.

  The solvent supply nozzle 51 is connected to a solvent supply system 53 via a pipe 52. The solvent supply system has the same configuration as the resist supply system except that the stored chemical is a solvent such as thinner instead of the resist. The thinner is a chemical solution for improving the wettability of the resist wafer W. A valve 54 corresponding to the valve 44 is interposed in the pipe 52. In FIG. 2, reference numeral 55 denotes an arm, and the solvent supply nozzle 51 is moved in the X-axis direction and the Z-axis direction by an arm drive unit 56 corresponding to the arm drive unit 46. Further, the resist coating apparatus 1 is provided with standby units 40 and 50 for waiting the resist supply nozzle 41 and the solvent supply nozzle 51 placed at the standby position, respectively. The standby units 40 and 50 have a role of receiving chemicals discharged from the resist supply nozzle 41 and the solvent supply nozzle 51, respectively.

  In addition, the resist coating apparatus 1 includes an edge remover 61. As shown in FIG. 2, the edge remover 61 includes an arm 63 having a nozzle 62 attached to a tip end thereof and capable of turning and raising and lowering. The edge remover 61 removes the resist film on the peripheral edge of the wafer W with a solvent in order to prevent film peeling after resist application.

  If the vicinity of the pump of the resist supply system 43 in the pipe 42 is an upstream portion 48, a strain gauge 71 </ b> A is provided in the upstream portion 48. A strain gauge 71B is provided at the tip of the resist supply nozzle 41. These strain gauges 71A and 71B are formed by forming a thin metal resistor in a predetermined pattern on a thin insulator, and the insulator side is bonded to the surfaces of the upstream portion 48 and the resist supply nozzle 41, for example. It is attached by doing. When the resist is pumped from the resist supply system 43, the resist supply nozzle 41 and the upstream portion 48 are deformed so as to swell, and the strain gauges 71A and 71B extend according to the deformation. The larger the amount of strain gauges 71A and 71B (the amount of strain) is, the greater the electrical resistance value of the metal resistor increases, and this change in resistance value can be detected as a change in strain amount. At this time, since the resistance values of the strain gauges 71A and 71B are minute values, they are converted into voltages using a Wheatstone bridge circuit.

  Specifically, as shown in FIG. 3, a strain sensor 70A forming a Wheatstone bridge circuit is configured by connecting a strain gauge 71A to the detector main body 72A. In the detection unit main body 72A, when the input voltage of the bridge circuit is applied from the battery 73, the output voltage of the bridge circuit is detected by the voltage detection unit 74A, and is output as the distortion detection voltage V to the differentiation circuit 75A. . In this example, the strain sensor 70A is configured such that the detection voltage V is 0 when the strain gauge 71A is not extended, and a negative detection voltage V is obtained when the strain gauge 71A is extended.

The differentiation circuit 75A differentiates the detection voltage V and outputs a voltage V ′. Comparison circuits 76A and 77A are connected in parallel to the subsequent stage of the differentiation circuit 75A. The comparison circuit 76A compares the voltage V ′ output from the differentiation circuit 75A with a preset reference voltage + V _0, and determines a voltage different depending on whether + V ₀ ≦ V ′ or V ′ <+ V ₀ . The data is output to the data processing unit 78A. The comparison circuit 77A compares the voltage V ′ output from the differentiation circuit 75A with a preset reference voltage −V _0, and determines whether −V ₀ <V ′ or V ′ ≦ −V ₀ . Different voltages are output to the subsequent data processing unit 78A. The reason why the reference voltages of the comparison circuits 76A and 77A are set to + V ₀ and −V ₀ in this way will be described later. The data processing unit 78A includes, for example, an A / D converter and converts the signals output from the comparison circuits 76A and 77B and outputs the converted signals to the control unit 80.

  FIG. 4 is a graph showing the relationship between the timing of resist supply and the change in the distortion amount of the upstream portion 48 of the pipe 42, that is, the change in the detection voltage V. From time t1 to t2, the resist is not supplied from the pump of the resist supply system 43, and the distortion amount of the upstream portion 48 is zero. When the resist is supplied from the resist supply system 43 at time t2, the upstream portion 48 gradually expands due to the stress received from the resist fed by pressure. When the supply of the resist is stopped at time t3, the amount of distortion gradually decreases due to the restoring force, and eventually returns to zero. When the supply of the resist is started again from the resist supply system 43 at time t4, the upstream portion 48 is again distorted. The resist supply nozzle 41 is also distorted in the same manner as the upstream portion 48 due to the resist supply from the resist supply system 43.

When the resist is supplied from the supply system 43 as described above, the distortion of the upstream portion 48 of the pipe 42 gradually increases. The voltage V ′ output from the differentiating circuit 75A has a negative value. When the supply of the resist from the supply system 43 is stopped and the distortion is decreasing, the voltage V ′ output from the differentiation circuit 75A becomes a positive value. When the resist is not discharged and the distortion is eliminated, the voltage V ′ output from the differentiating circuit 75A is zero. However, in order to prevent erroneous detection due to noise, in this example, a threshold value V ₀ is provided, and when −V ₀ <V ′ = 0 <+ V ₀ , no resist is discharged, and distortion is eliminated. As described above, the control unit 80 described later can make a determination. The table of FIG. 5 shows the output from the comparison circuits 76 and 77 subjected to A / D conversion, the range of the output voltage V ′ from the differentiation circuit 75, and the discharge of the resist onto the wafer W determined by the control unit 80. The relationship with the state is shown. As shown in this table, when + V ₀ ≦ V ′, the control unit determines that the distortion of the pipe 42 is reduced after the discharge is completed, and that when V ′ ≦ −V _0, it is determined that the resist is being discharged. 80 is configured.

  Although each part connected to the strain gauge 71A has been described, similar parts are also connected to the strain gauge 71B as shown in FIG. The parts corresponding to each part and each circuit connected to the strain gauge 71A are denoted by B instead of A, and the description thereof is omitted. Each detection unit main body 72, differentiation circuit 75, comparison circuits 76 and 77, and data processing unit 78 constitute a circuit unit 79.

  In the resist supply nozzle 41, similarly to the upstream portion 48 of the pipe 42, the amount of distortion varies depending on the resist discharge state as shown in FIG. 4, and the resist discharge state of FIG. In this example, the determination of the resist discharge state in FIG. 5 is normally performed using the strain gauge 71A. When the bubble 64 generated by, for example, foaming of the resist passes through the upstream portion 48 of the pipe 42 during the resist discharge, as shown at time t5 in FIG. 7, the amount of distortion that has continued to increase temporarily decreases, Then it grows again. Similarly, when the bubble 64 passes through the resist supply nozzle 61, the amount of distortion of the resist supply nozzle 61 changes. Using this, when bubbles are detected by the strain gauge 71A, the removal of the bubbles 64 is confirmed by the strain gauge 71B, as will be described in the operation of the resist coating apparatus 1 described later.

  Next, the control unit 80 of the resist coating apparatus 1 will be described with reference to FIG. The control unit 80 is constituted by, for example, a computer, and reference numeral 81 in FIG. 8 is a bus. A CPU (Central Processing Unit) 82, a storage unit 83, a program storage unit 84, a display unit 85, an alarm display unit 86, and a timer 89 are connected to the bus 81. The program storage unit 84 stores a processing program 87 for performing a resist coating process on the wafer W, a determination program (determination unit) 88 for performing various determinations as will be described later, and the like.

  A control signal is transmitted from the control unit 80 to each unit of the resist coating apparatus 1 by the processing program 87, and a resist coating process is performed on the wafer W. The processing program also performs processing such as storing the resist discharge start time and resist discharge end time, and calculating the discharge time. The determination program 88 performs various determinations based on the output from the circuit unit 79. The program storage unit 84 is configured by a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card. Each program is installed in the control unit 80 from the program storage unit 84 and operates.

  The storage unit 83 stores a resist discharge start time, a discharge end time, and a resist discharge time calculated from the discharge start time and discharge end time for each wafer W. The storage unit 83 also stores an output time of a discharge start signal for starting discharge of resist and an output time of a discharge stop signal for stopping discharge of resist. The display unit 85 includes a display, for example, and displays the discharge start time, discharge end time, discharge time, and output time of each signal stored in the storage unit 83 for each wafer W. The alarm generation unit 86 includes, for example, a buzzer that emits a warning sound and a display for displaying a warning, and notifies the operator of the resist coating apparatus 1 of the abnormality of the apparatus 1. The timer 89 is a means for measuring the resist discharge time, and is arbitrarily set by an operator via an input unit (not shown).

  Next, a coating process step on the wafer W by the resist coating apparatus 1 will be described with reference to a flowchart of FIG. For example, when the operator performs a predetermined processing start operation, the wafer W is transferred to the resist coating apparatus 1 by the transfer unit 14 and is transferred to the spin chuck 21 by the cooperative operation of the transfer unit 14 and the lifting mechanism 39. The solvent supply nozzle 51 moves from the standby unit 50 onto the center of the wafer W, the wafer W rotates at, for example, 1500 rpm, and thinner is supplied to the center, and the supplied thinner spreads wet to the periphery.

  As the solvent supply nozzle 51 returns to the standby unit 50, the resist supply nozzle 41 moves from the standby unit 40 onto the center of the wafer W, and the rotational speed of the wafer W increases to, for example, 3000 rpm. At this time, the controller 80 determines whether or not the outputs from the comparison circuits 76A and 77A are 0 and 1, that is, whether or not the resist is discharged (step S1). If it is determined that the resist is being discharged, it is determined that there is an abnormality in the apparatus, and an alarm is output (step S2).

  When it is determined in step S1 that the resist is not discharged, the control unit 80 outputs a resist discharge start signal to the resist supply system 43 and stores the output time of the discharge start signal in the storage unit 83 (step S3). . Then, after the discharge start signal is output, it is determined whether or not the outputs from the comparison circuits 76A and 77A become 0 and 1, respectively, that is, whether or not the resist is discharged within a preset time (step S4). .

  If it is determined in step S4 that the resist is not discharged within the set time, the control unit 80 outputs an alarm that the apparatus is abnormal. When it is determined in step S4 that the resist is discharged within the set time, the control unit 80 writes the time as the discharge start time in the storage unit 83 (step S5), and drives the timer 89 (step S6).

The control unit 80 determines whether or not the outputs from the comparison circuits 76A and 77A are 1 and 0, that is, whether or not the amount of distortion of the pipe 42 has decreased (step S7).
If it is determined in step S7 that the amount of distortion has not decreased, the control unit 80 determines whether or not the timer 89 is up (step S8). If it is determined that the timer 89 is not up, Returning to S7, the determination is repeated. When it is determined in step S8 that the timer 89 is up, the control unit 80 outputs a discharge stop signal and stores the output time of the discharge stop signal in the storage unit 83 (step S9). Then, after the discharge stop signal is output, it is determined whether or not the outputs from the comparison circuits 76A and 77A become 1, 0 within a preset time, that is, whether or not the resist discharge is stopped (step). S10)

  If it is determined in step S10 that the resist ejection has not been stopped within the set time, the control unit 80 outputs an alarm. When it is determined in step S10 that the outputs from the comparison circuits 76A and 77A become 1, 0 within the set time, the time when the output becomes 1, 0 is written in the storage unit 83 as the ejection stop time (step S11). The timer 89 is reset (step S12).

The resist supplied to the wafer W is supplied to the entire surface of the wafer W by spin coating. For example, the rotation speed of the wafer W becomes 2000 rpm, and the resist is dried. The resist supply nozzle 41 returns to the standby unit 40, and the edge remover 61 supplies a solvent to the peripheral portion of the wafer W, and the resist film on the peripheral portion of the wafer W is removed. Thereafter, the rotation of the wafer W is stopped, and the wafer W is transferred to the transfer means (not shown) by the lift pins 39 and is unloaded from the resist coating apparatus 1. Thereafter, the subsequent wafer W is transferred to the resist coating apparatus 1.

  When the outputs from the comparison circuits 76A and 77A become 1, 0 in step S7, the control unit 80 determines that the bubble 64 is included in the resist (step S13). After this determination, the operations of Steps S8 to S12 are performed, the resist supply nozzle 41 returns to the standby unit 40, and after the processing on the wafer W being processed is completed, the subsequent wafer W is applied to the resist coating apparatus 1. The conveyance is temporarily stopped. A discharge start signal is output to the resist supply system 43, and the resist is discharged from the resist supply nozzle 41 to the standby unit 40 (step S14). The control unit 80 determines whether or not the outputs of the comparison circuits 76B and 77B become 1, 0 within a preset time and then become 0, 1, that is, the bubble 64 is generated in the resist supply nozzle 41 remaining in the pipe 42. It is determined whether it has been sent out and removed.

  When it is determined that the bubbles 64 have been removed, the control unit 80 outputs a discharge stop signal to the resist supply system 43. Then, the transfer of the wafer W by the transfer means 14 is resumed, and the processing is continued. If it is determined that the bubbles have not been removed, a discharge stop signal is output to the resist supply system 43 and an alarm is output. The process of removing the bubbles 64 can also be performed manually by an operator. In this case, for example, the output result of each of the comparison circuits 76 and 77 is displayed on the display unit 85, and the operator controls the discharge and stop operations of the resist while referring to the output result.

  For example, when a predetermined number of wafers W are processed repeatedly, the resist coating apparatus 1 causes the old resist in the pipe 42 and the resist supply nozzle 41 to flow away, and a dummy for preventing the resist from solidifying in the pipe 42 and the nozzle 41. Dispense. This dummy dispensing is performed in the same process as when the resist is supplied to the wafer W, except that the resist discharge destination is the standby unit 40 instead of the wafer W and the set time of the timer 89 is different. That is, the above steps S are executed. After the dummy dispense is executed, the process on the wafer W is performed again.

  Also during the maintenance of the resist coating apparatus 1, the same processing as that for the processing of the wafer W is performed. However, the wafer W to be processed at the time of maintenance is a dummy wafer not intended for manufacturing a semiconductor device. For example, the operator of the resist coating apparatus 1 stops the operation of the apparatus 1 every time a predetermined number of wafers W are processed, and the resist discharge start time, resist supply stop time, and discharge start on the wafer W displayed on the display unit 85. Based on the output time of the signal and the discharge stop signal, the operation of the pump of the resist supply system 43, the condition of the opening / closing operation of the valve 44, and the like are adjusted.

  According to the resist coating apparatus 1, the detection voltage of the strain sensor 70A is differentiated by the differentiation circuit 75A, and the resist discharge start time and discharge end time are detected according to the output of the differentiation circuit 75A. Therefore, compared to the case where the discharge start time and discharge end time are detected by the optical detection means, the surface condition of the wafer W and the color of the resist are not affected, so that the resist is normally discharged. It is possible to detect with high accuracy whether or not

  By the way, as described in the item of the background art, there may be a case where after the wafer W is processed, the next wafer W must be processed before the distortion of the nozzles and piping is completely recovered. However, depending on the material of the nozzle and the pipe, the time until the distortion is eliminated after receiving the stress is slow. In such a case, the presence or absence of distortion based on the magnitude of the detected voltage value of the strain sensor 70A, that is, It is difficult to set a threshold value when determining the resist discharge state. Therefore, when determining the presence or absence of distortion based on the magnitude of the detected voltage value, the material used for the nozzle and piping is made of a material having high rigidity such as metal in order to eliminate the distortion quickly. However, the degree of freedom in selecting materials is limited, and it is costly to process and install in equipment, and it is necessary to select materials that have a small amount of strain with respect to stress, which reduces detection accuracy. There is a risk that. However, by adopting a configuration for differentiating the detection voltage as described above, the degree of freedom of the material used for the nozzle and the pipe is increased. Since a material having a relatively large strain amount with respect to stress such as resin can be selected, the detection accuracy can be improved also in this respect.

  In addition, when applying a resist by spin coating as described above, it is necessary to control the timing of supply of the resist in accordance with the change in the rotation speed of the wafer. This timing is shifted for each resist coating apparatus, and maintenance is performed so that the processing on the wafer does not vary. Since the resist coating apparatus 1 can detect the discharge state of the resist with high accuracy as compared with the case where an optical detection unit is used, the timing of the supply start can be accurately known, so that the maintenance is facilitated. There is. In addition, since the resist coating apparatus 1 can detect the time point when the resist discharge is stopped, maintenance can be easily performed so that an error in the resist supply time can be suppressed between the apparatuses.

  In the above example, the determination of the discharge state of the resist is performed based on the detection result of the strain sensor 70A provided in the pipe 42, but may be performed based on the output of the strain sensor 70B provided in the nozzle 41. However, when the bubble 46 is detected in the pipe 42 as described above, the removal process of the bubble 46 can be performed, and unnecessary processing can be prevented from being performed on the wafer W. It is more preferable to make a determination based on the detection result.

  The present invention can also be applied to a developing solution supply apparatus that supplies a developing solution to a substrate instead of a resist, and a liquid processing apparatus that supplies various other chemical solutions.

(Reference test)
Resist was discharged from the resist supply nozzle 41, and the amount of distortion was measured based on the output from the voltage detection unit 74B. The resist supply nozzle 41 is made of resin. In each test, the output voltage of the voltage detector 74B is not differentiated. For each test, the resist supply time from the resist supply system 43 was changed to 0.5 seconds, 1.0 second, and 2.0 seconds in Tests 1, 2, and 3, respectively. In Test 4, air was mixed near the nozzle 41 in the pipe 42 and the resist was supplied from the resist supply system 43 for 1.0 second.

  FIGS. 10A and 10B show the results of Tests 1 and 2, respectively. In addition, FIGS. 11A and 11B show the results of tests 3 and 4, respectively. A section t1-t2 in the table is a section in which the resist is supplied. As shown in these figures, after the resist supply is stopped, the distortion of the resist supply nozzle 41 gradually returns. Therefore, as described above, there may be a case where the process is performed on the next wafer W before the distortion is eliminated. In order to prevent the setting of the threshold value from becoming difficult at that time, as in the above-described embodiment. It can be said that it is effective to provide a differentiating circuit to detect the supply state of the resist. Further, when air is mixed as shown in FIG. 11B, the change in the amount of distortion is suppressed, and the change in the amount of distortion is increased after the air is removed. Therefore, it can be seen that the bubble can be detected as described above by changing the amount of distortion.

DESCRIPTION OF SYMBOLS 1 Resist coating apparatus 14 Conveying means 22 Rotation drive part 3 Cup 41 Resist supply nozzle 42 Piping 43 Resist supply system 70A, 70B Strain sensor 71A, 71B Strain gauge 75A, 75B Differentiating circuit 79 Circuit unit 80 Control part 88 Determination program

Claims (11)

In an apparatus for supplying a chemical solution from a pump through a pipe and a nozzle to a substrate held by a substrate holding unit and performing a liquid treatment
A strain sensor provided with a strain gauge in the flow path component from the pipe to the tip of the nozzle;
A differentiating circuit for differentiating the output voltage of the strain sensor;
A liquid processing apparatus comprising: a determination unit that determines a supply state of the chemical liquid according to an output of the differentiation circuit.   The liquid processing apparatus according to claim 1, wherein the strain gauge is provided in a pipe made of resin.   The liquid processing apparatus according to claim 1, wherein the strain gauge is provided in a nozzle made of resin. The strain sensor is configured such that when the strain gauge is extended, the output voltage has one sign of positive and negative,
The determination unit is configured to determine that a chemical solution has flowed when the output voltage of the differentiating circuit is the one sign and the absolute value is greater than a predetermined threshold value. The liquid processing apparatus according to any one of 1 to 3.   The determination unit determines that the flow of the chemical solution has stopped when the output voltage of the differentiating circuit has a sign opposite to the one sign and the absolute value is greater than a predetermined threshold value. The liquid processing apparatus according to claim 4, wherein the liquid processing apparatus is configured as described above.   When the elapsed time after determining that the chemical solution has flowed is shorter than a predetermined set time, the output voltage is a sign opposite to the one sign, and the absolute value is determined in advance. The liquid processing apparatus according to claim 4, wherein the liquid processing apparatus is configured to determine that bubbles are included in the chemical liquid when the threshold value is larger than the threshold value. A step of holding the substrate in the substrate holding portion;
A step of supplying a chemical solution from the pump to the substrate through a pipe and a nozzle to perform a liquid treatment;
Differentiating the output voltage of a strain sensor including a strain gauge provided in a flow path component from the pipe to the tip of the nozzle with a differentiation circuit;
Determining the supply state of the chemical solution according to the output of the differentiation circuit;
A liquid treatment method comprising: Outputting a voltage of one of positive and negative signs from the strain sensor when the strain gauge is extended;
A step of determining that the chemical solution has flowed when the output voltage of the differentiating circuit is the one of the signs and the absolute value is greater than a predetermined threshold;
The liquid processing method according to claim 7, further comprising:   A step of determining that the flow of the chemical solution has stopped when the output voltage of the differentiating circuit has a sign opposite to the one sign and the absolute value is greater than a predetermined threshold value; The liquid processing method according to claim 8.   When the elapsed time after determining that the chemical has flowed is shorter than a predetermined set time, the output voltage is a sign opposite to the one sign, and the absolute value is lower than a predetermined threshold value. The liquid processing method according to claim 8, further comprising a step of determining that bubbles are included in the chemical liquid when it becomes large. In a storage medium for storing a program used in a liquid processing apparatus that supplies a chemical solution from a pump via a pipe and a nozzle to a substrate held by a substrate holding unit,
11. A storage medium characterized in that the program includes a group of steps so as to execute the liquid processing method according to any one of claims 7 to 10.

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