KR100667125B1 - Process and system for determining acceptability of a fluid dispense - Google Patents

Abstract

The present invention is directed to a method and system for determining the water solubility of a fluid distribution, such as the volume of discontinuous fluid 30 used to coat a substrate. The fluid distribution is exposed to energy sources 16 and 24 and the energy delivered by the fluid distribution is detected to determine the shape of the fluid distribution. The shape of the fluid dispense and the start and end timing of the dispense are compared to a previously generated standard dispense profile and used to determine the fluid dispense timing and / or acceptability of the shape. Outputs from sensors 18 and 26 are used to control other processing of the substrate.

Fluid Dispensing, Discontinuous Fluid Volume, Dispenser, Emitter, Sensor, Dispense Timing

Description

PROCESS AND SYSTEM FOR DETERMINING ACCEPTABILITY OF A FLUID DISPENSE

The present invention relates to an apparatus and method for monitoring the integrity and timing of a fluid dispense. In particular, the present invention relates to an apparatus and method for monitoring in real time the retention of a fluid distribution.

Various industries need to deliver the correct volume of liquid at a constant rate over a period of time that can be quite repeatable. In addition, at the end of the transfer, subsequent processing will occur where timing for the transfer is important for process consistency and product uniformity. For example, the exact volume of the photoresist mixture is transferred to the silicon wafer substrate to form a layer of photoresist of uniform thickness on the wafer. The wafer is rotated at high speed after liquid transfer to uniformly distribute the liquid on the wafer. The requirements for accurate volume and rate of transport during dispensing should be influenced by a device that repeatedly delivers the same volume of liquid at a constant rate of transfer over a period of time that can be repeated many times over a long period of time.

As the semiconductor industry is expected to use ultrafine technology, photoresist and low dielectric liquid mixtures are becoming increasingly important to improve the performance of microprocessors and memory storage devices. In order to reduce manufacturing costs and reduce photoresist waste, lower doses of liquid photoresist and lower viscosity liquids will be dispensed. Coating these liquids onto a wafer requires a high degree of uniformity in thickness across the wafer and thickness per wafer. In order to achieve the high production yields and required uniformity of the films formed from these fluids, the fluid dynamics and the timing of the liquid dispensed onto the wafer are important. For example, a broken flow of liquid impinging on a wafer caused by droplets or bubbles in a distribution nozzle or tubing is a common cause of wafer defects that affect the uniformity of a film formed from liquid. The increase in defects leads to an undesirable increase in production costs.

The fluid dispensed onto the wafer becomes a uniform film on the wafer by rotating the wafer at low speed as the fluid is dispensed, and then sprays the liquid evenly across the wafer to cause evaporation of the photoresist or low K dielectric solvent. Increase the speed of rotation up to the final speed of rotation, the so-called spin up phase. The time that the wafer is held at the final rotational speed is important for reproducibly forming thick and uniform coatings. Knowing the time between the end time of fluid distribution and the time to final spin up when the liquid leaves the nozzle is important to control the time at which the wafer is rotated at high rotational speeds to achieve coating uniformity. The importance of various variables on coating uniformity is second. Electrochem. Illustrated by Doton and Givens (1992) (vol. 129, p173) by J. Electrochem. Soc.

Providing an electronic rain gauge has been proposed in International Application No. 98/00736. A container is provided to collect rainwater and convert the collected water into a defined volume of droplets through the orifice. The volume of the ratio is determined by calculating the droplet of liquid from the collector. This is accomplished by an optical emitter and optical receptor pair such that a voltage change or pulse is generated when liquid droplets pass between the emitter and the receiver. By calculating the number of voltage pulses and multiplying the volume of the droplets, the total amount of rainfall can be determined. No means are provided for monitoring the shape of the droplets and the device departure time of the droplets, and for detecting irregularities and shape of the droplets or for incorporating the output signal from the emitter pair as an input signal into a wafer rotating coater or fluid distribution pump. No means are provided. Conversely, when monitoring liquid distribution onto a silicon wafer, the distribution is monitored in such a way that the volume of the dispense can be determined as well as not only determining whether the dispense is applied to each wafer in a consistent manner, including the dispense time and the shape of the dispense fluid. Means for this need to be provided. This requirement necessitates monitoring the timing and shape of the fluid distribution so that the rate of fluid application from the initial contact, intermediate contact and final contact between the fluid and the substrate to the substrate is essentially redundant over a long period of time.

Accordingly, it would be desirable to provide an apparatus and method for monitoring the transfer of accurate liquid volumes with repeatable proportions, fluid dynamics, volumes, and transfer intervals. In addition, in a production line on a real-time basis, it is desirable to provide an apparatus and method that can monitor the transfer of accurate liquid volumes at a repeatable rate over a long period of time and use such information for process control.

According to the invention, a dynamic time dependent profile of the liquid dispensed from the nozzle is generated and analyzed. The profile thus produced is compared with a standard profile correlated with the profile, volume and time for satisfactory liquid distribution. When the resulting profile is considered satisfactory in volume, timing and shape, further processing for the liquid dispensed onto the substrate, such as a silicon wafer, continues to perform further processing for the liquid coated substrate. The light generator and the light detector are mounted under the nozzle through which the liquid is dispensed and are located on opposite sides of the path of the liquid dispense flow. Other forms of energy from generators, including but not limited to heat, acoustics or other types of electromagnetic energy, can also be used in conjunction with suitable detectors. Thermal energy emitted from the sample itself can also be considered an energy source for a suitable detector. Although light energy will be used as an example for the description of the present invention, other types of energy and sensors may be used interchangeably.

During the dispensing process, the liquid flow will absorb or disperse a portion of the light from the light generator, while light delivered from or dispersed through the liquid is collected by the detector. The amount of light transmitted from the flow absorbed or dispersed depends on the continuity and diameter of a given liquid flow emitted from the fluid distribution nozzle. As the rate at which the liquid is dispensed is changed or stopped, the diameter of the liquid flow decreases and stops, increasing the amount of light reaching the detector. By recording the amount of light collected over time and converting the measurement into an appropriate electrical signal, the fluid dynamics and time dependent profile of the distribution are obtained. This signal is then compared to a pre-generated standard signal for satisfactory liquid distribution to determine the acceptability of the distribution for the intended purpose. Alternatively, the signal obtained from the sensor is used to determine dispensing timing and end of dispensing, and to initiate subsequent fluid processing steps such as spin-up or decompression application to the chamber. The profile is used to control one or more stationary reverse intake valves and / or spinner spindles of the system.

In accordance with the present invention, the process and system monitors the light or energy transfer characteristics of the fluid distribution and compares the monitored properties with previously generated standard distributions to determine whether the fluid distribution meets a specific purpose, such as coating on a substrate. Provided to determine. Also provided by this system is a means for using the signal provided to determine the time when the last fluid leaves the dispensing nozzle and to initiate a subsequent processing step. Fluid is dispensed from the nozzle and passes through at least one detector set, each of which includes an energy emitter and an energy detector. For example, photons from the emitter pass through the fluid distribution and photons delivered through the fluid distribution are detected by the detector. Then, the graph related to the degree of photon transfer over time is compared with the standard graph to determine whether the distribution is satisfactory. The total distribution volume is exposed to the emitted photons such that the graph characterizes the total distribution. When it is determined that the dispensing is satisfactory, a coating process or the like in which dispensing such as spin-up is used may be continued. When it is determined that the distribution is unsatisfactory, the dispensing object is removed from other processing. For example, when coating a silicon wafer with photoresist or a low K dielectric or other material, the wafer coated with an unsatisfactory distribution is removed in another process and the dispensing fluid is removed by solvent extraction or the like. In this example, significant economic savings are realized by allowing the recovery of acceptable unprocessed wafers that would otherwise become unacceptable when further processed, such as when unsatisfactory photo-treatment was performed on the coated wafer.

Another embodiment of the present invention measures the energy dispersed or reflected from the substrate through at least one detector set, each comprising an energy emitter and an energy detector. The energy from the emitter impinges on the fluid distributed over the substrate and the energy reflected from the fluid distributed over the substrate is detected by the detector. Thereafter, the graph relating to the degree of dispersion of energy over time is compared with the standard graph to determine whether the distribution is satisfactory. The wafer is exposed to radiated energy such that a graph of dispersed or reflected energy represents the overall distribution characteristics on the wafer.

1 is a schematic view showing the apparatus of the present invention.

Figure 2 shows a satisfactory distribution measured by the apparatus of the present invention.

3 shows an unsatisfactory distribution measured by the apparatus of the present invention.

4A is a diagram of the signal output generated by the apparatus of the present invention showing an unsatisfactory distribution identified in accordance with the present invention.

4b is a diagram of the signal output produced by the apparatus of the present invention showing a satisfactory distribution identified in accordance with the present invention.

5 is a circuit diagram for converting detection light transmitted through distribution into a real-time graph of distribution light transmission characteristics.

Figure 6 shows an example of a suitable distribution for a period of 0.25 to 3 seconds, as measured by the apparatus of the present invention.

7 is an example of an unsatisfactory distribution as measured by the apparatus of the present invention.

8 is a plot for determining the sensitivity of the apparatus of the present invention to distinguish distributions of different time periods.

Satisfactory fluid distribution is that formed from a single discrete fluid volume rather than a plurality of discrete fluid volumes. When a plurality of discontinuous fluid volumes are dispensed, the resulting coating on the substrate is characterized by a more variable thickness or stripe than the uniform coating produced by a single discontinuous fluid volume. Thus, the signal response produced by a single discontinuous fluid volume passing through the sensor device results in an initial measurement point where the fluid is not interposed between the photon emitter and the photon detector and the fluid is not interposed between the photon emitter and the photon detector. It features a smooth curve between the end points of the measurement. In contrast, the curve produced by the plurality of discrete fluid volumes is characterized by at least one peak or depression during periods of little or no fluid between the discrete fluid volumes. The depression is obtained when the back transfer of photons is measured, while the ridge is obtained when the energy transfer is measured directly.

One or a plurality of energy detectors may be used. When multiple detector sets are used, the detector sets are positioned spaced apart from each other along the path of travel of the fluid distribution. Two or three detector sets may be used to provide a means for confirming initial measurements. Alternatively, the detector and emitter sets may be positioned around the fluid distributor and inclined such that the detector measures the energy reflected or dispersed from the substrate or distribution volume coated with a portion of the fluid.

Referring to FIG. 1, the system of the present invention is provided in a container for fluid (not shown) dispensed from a nozzle by any conventional means, such as pumping fluid, etc. by gravity, fluid pressurization, appropriate conventional valving. And a connected nozzle 10. The dispensed fluid 12 may comprise a first detector set 14 comprising an energy emitter such as an infrared or visible light emitting diode, or an acoustic wavelength generator and a phototransistor, photoresist, thermopile, charge coupling device or It passes between the energy detectors 18, such as a microphone, by gravity or the like. Detector 18 is electrically connected to a conventional signal processor 20 that can produce a graph of energy delivery or a graph of energy absorbed by the liquid dispensed over a period of time. A second emitter and detector set 22 comprising an energy emitter 24 and an energy detector 26 is located downstream of the first detector set 14. The energy detector 26 is electrically connected to a conventional signal processor 20 that can produce a graph of photons absorbed by the fluid 30 dispensed over time or a second graph of photon transfer.

Referring to FIG. 2, a satisfactory distribution is shown that includes a single discrete volume 32 passing between photon emitter 16 and photon detector 18. This satisfactory distribution causes signal processor 20 to generate the curve shown in FIG. 4B. The initial measurement 36 by the detector 18 where the distribution was not located between the emitter 16 and the detector 18 and the distribution was not located between the photon emitter 16 and the detector 18. Between the final measurement 38 by the detector 18, the curve 34 has no spikes or depressions.

Referring to FIG. 3, an unsatisfactory distribution is shown that includes a plurality of discrete volumes 31, 33, 35 passing between emitter 16 and detector 18. This unsatisfactory distribution causes the signal processor 20 to generate the curve 40 shown in FIG. 4A. Initial measurement 46 by detector 18 with dispensing not located between emitter 16 and detector 18 and detector with dispensing not located between emitter 16 and detector 18. Between the final measurements 48 by 18, the curve 34 has spikes 42 and 44 (or depressions). Spikes 42 and 44 include measurements when discrete volumes 33 and 31 pass between emitter 16 and detector 18, respectively.

Referring to Figure 5, a schematic diagram of a processor capable of detecting a signal from a sensor, processing the signal in an appropriate form, comparing the signal with a standard distribution, and sending the signal to a process unit to operate based on the comparison result Is shown.

Example 1

) 펌프로부터 분배되었다. 액체는 에틸락테이트계 용매에 용해된 포토레지스트를 포함하였다. 레지스트는 센서와 이미터 쌍을 통해 펌프에 의해 분배되었고, 회로 부품판 상에 장착되었으며, 전자 저울 상의 50 ml 플라스크 내에 수집되었다. 분배된 액체에 대한 질량 측정은 이전 분배와 다른 질량에 의한 각 분배 뒤에 이루어졌다. 센서로부터의 0 내지 5 볼트 출력이 20mm/sec로 설정된 차트 속도를 갖는 킵 앤드 조넨(Kipp and Zonen) 스트립 차트 기록기에 의해 측정되었다.A pair of light emitters and light detectors were configured for sensing fluid distribution. Emitter detector pair, Tandy part number 276-142, was connected to a 468 ohm resistor attached to the emitter and sensor leads. The ridge wavelength length of the emitter is 915 nm. The emitter and sensor are cut and spaced 0.8 cm apart and mounted on a breadboard. The size of the device was 5.0 inches by 5.0 inches (2 inches by 2 inches). Monitored liquids are trade names Millipore's Intelligen

) From the pump. The liquid contained a photoresist dissolved in an ethyl lactate solvent. The resist was dispensed by a pump through a sensor and emitter pair, mounted on a circuit board, and collected in a 50 ml flask on an electronic balance. Mass measurements on the dispensed liquid were made after each dispense by a different mass than the previous dispense. The 0-5 volt output from the sensor was measured by a Kipp and Zonen strip chart recorder with a chart speed set to 20 mm / sec.

Figure 6 illustrates a preferred distribution of photoresist measured by the device described in the present invention. The sensor response shows the distribution within a period of 0.25 seconds to 3 seconds.

FIG. 7 illustrates an undesirable distribution that includes an irregular flow of fluid generated by a plurality of droplets that exhibits the characteristics of an undesirable distribution. Comparison of FIG. 6 and FIG. 7 provides a means for determining that the distribution shown in FIG. 7 is unacceptable in terms of shape and timing compared to the distribution of FIG. 6.

FIG. 8 is a graph of another distribution shown in FIG. 6 plotted against time for distribution. The minimum linear regression of this data shows that in one sigma confidence interval, the performance of the inventive device of Example 1 can identify durations of different distributions within 33 ms.

It will be understood that these are examples of the apparatus of the invention described. Appropriate modifications to such devices, including but not limited to high speed timing equipment and other sensors, will be apparent to those skilled in the art.

Claims (22)

Method for determining the water solubility of a fluid distribution, Providing a dispenser for dispensing a discontinuous fluid volume comprising the fluid distribution from a container containing a fluid, dispensing the discontinuous fluid volume from the container through the dispenser; Investigating the discontinuous fluid volume with energy from an emitter, Detecting energy delivered from the discontinuous fluid volume to identify a profile of the fluid distribution; Comparing the profile with a previously identified standard profile to determine water solubility of the fluid dispense. The method of claim 1, wherein the detection of energy delivered from the discontinuous fluid volume is used to determine the time at which the fluid began to flow from the dispensing device and the time the fluid flow stopped. System for determining the water solubility of a fluid distribution, A dispenser for dispensing the discontinuous fluid volume from the vessel containing the fluid, One or more energy sources for irradiating the discontinuous fluid volume with energy; One or more sensors for detecting energy delivered from the discontinuous fluid volume to identify a profile of the fluid distribution; Means for comparing the profile with a previously identified profile to determine water solubility of the fluid distribution. 4. The system of claim 3, wherein sensors for detecting energy delivered from the discontinuous fluid volume are used to determine when fluid flow is initiated from the dispensing device and when fluid flow is stopped. The method of claim 1, wherein said investigating and detecting are performed at least twice. The method of claim 1, wherein the irradiating and detecting are performed by measuring the energy reflected from the surface to which the fluid is dispensed. The system of claim 3, wherein the one or more energy sources are a plurality of energy sources for irradiation and the one or more sensors are a plurality of sensors for detection. A method for determining the water solubility of a fluid distribution for coating a substrate in a second process for modification, Dispensing the discontinuous fluid volume comprising the fluid from the vessel containing the fluid onto the substrate; Examining the discontinuous fluid volume with energy from an energy emitter; Detecting energy delivered from the discontinuous fluid volume to identify a profile of the fluid distribution; Comparing the profile and dispense timing with a pre-identified standard profile or response output to determine dispense timing and acceptability of the fluid dispense; Removing the substrate from the second process if it is determined that the fluid distribution is unacceptable. The method of claim 8, wherein said investigating and detecting are performed at least twice. The system of claim 3, wherein the one or more energy sources are selected from the group comprising heat, sound and electromagnetic energy. The system of claim 3, wherein the one or more energy sources are light. The method of claim 1 wherein the energy from the emitter is selected from the group comprising heat, sound and electromagnetic energy. The method of claim 1, wherein the energy from the emitter is light. The method of claim 8, wherein the energy from the emitter is selected from the group comprising heat, sound and electromagnetic energy. The method of claim 8, wherein the energy from the emitter is light. The method of claim 1, wherein the profile is used to determine when dispensing is stopped and to control one or more stop reverse intake valves of the dispensing system. The method of claim 1, wherein the profile is used to determine when dispensing is stopped and to control the spinner spindle of the system. The method of claim 1, wherein the profile is used to determine when dispensing is stopped and to control subsequent dispensing timing by the dispensing system. 4. The system of claim 3, wherein sensors for detecting energy from the energy source collected from the discontinuous fluid volume dispensed are used to determine when fluid flow starts from a dispensing device and when fluid flow stops. The system of claim 3, wherein the profile from the sensor indicates the end of fluid dispense and is used to control one or more reverse intake valves and spinner spindle and subsequent dispense timing of the system. The system of claim 3, wherein the profile from the sensor indicates the end of fluid dispensing and is used to control the spinner spindle of the system. The system of claim 3, wherein the profile from the sensor indicates the end of fluid dispense and is used to control subsequent dispense timing.

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