WO2008069513A1

WO2008069513A1 - Process control method using apparatus for measuring substrate warpage, recording medium in which program for executing the process method is recorded and process apparatus for performing the process method

Info

Publication number: WO2008069513A1
Application number: PCT/KR2007/006175
Authority: WO
Inventors: Bong Kee; Eui-Joon Yoon
Original assignee: Nanotron Technologies, Inc.
Priority date: 2006-12-04
Filing date: 2007-12-03
Publication date: 2008-06-12
Also published as: KR100731924B1

Abstract

Provided are a method and apparatus for measuring substrate warpage after each process is completed, so as to easily and quickly determine whether each operation of a semiconductor device fabricating process is performed within standard requirements, a recording medium in which a program for executing the process method is recorded, and a process apparatus for performing the process method. The process method includes: installing a curvature measuring unit on a transfer path of a substrate within a clean room; and measuring warpage of the substrate in real-time while the substrate is transferred. The whole substrate in process can be inspected without using an additional space within a clean room and without additional burden of a measuring time so that, in view of process control, data for more precise control can be provided.

Description

PROCESS CONTROL METHOD USING APPARATUS FOR MEASURING SUBSTRATE WARPAGE, RECORDING MEDIUM

IN WHICH PROGRAM FOR EXECUTING THE PROCESS METHOD IS RECORDED AND PROCESS APPARATUS FOR

PERFORMING THE PROCESS METHOD Technical Field

[1] The present invention relates to statistical process control of a semiconductor device fabricating process, and more particularly, to a method and apparatus for measuring substrate warpage after each process is completed, so as to determine whether each operation of a semiconductor device fabricating process is performed within standard requirements. Background Art

[2] A semiconductor device fabricating process is comprised of many unit processes.

New thin layers may be formed through unit processes, the shape of the thin layers may be changed by photolithography, or a microstructure of the thin layer may be changed by thermal treatment.

[3] In general, when a thin layer is formed of material that is different from a substrate material (or an underlay er), due to a difference in thermal expansion coefficients between the substrate material (or the underlayer) and the material of the thin layer or lattice constant inconsistency thereof, stress occurs in the thin layer. Due to stress, substrate warpage occurs, and in severe cases, delamination occurs between the substrate material (or the underlyaer) and the material of the thin layer. Stress within the thin layer causes serious deterioration in material characteristic of the thin layer and thus is not preferable. For example, a semiconductor device including a stressed thin layer losses a desired electrical characteristic so that deterioration of performance of a device and error in electrical wiring occur. Thus, it is important to carry out precise measurement of stress, i.e., to monitor warpage of a substrate, so as to minimize internal stress and understand an effect thereof.

[4] In case of forming thin layers, there are many cases where unintended thin layers are formed due to a change in process variants such as a process time, a process temperature, and a flow adjusting device etc. This causes a change in thin layer composition and microstructure and a change in thickness so that a change in stress to be applied to thin layers occurs. Also, even though a thin layer forming process is well controlled and a thin layer having a desired thickness, composition, and microstructure is formed, when the thin layer to which predetermined stress is applied is formed and then part of the thin layer is patterned by photolithography, a degree for releasing stress is different according to the shape of patterns caused by an inclination of an etched surface or overetching, and this causes a change in stress state of a thin layer/ substrate structure indirectly and a change in substrate warpage occurs finally.

[5] In this way, when substrate warpage is measured using a change in curvature of a substrate after each unit process, it can be known whether the process can be reproduced or not, and in view of production, it can be known whether each process is within standard requirements. Even at the present, there is a conventional apparatus for measuring substrate warpage after each unit process. However, the conventional apparatus is a separate apparatus that is spaced apart from a process apparatus in which unit processes are performed, and thus, part of the substrate must be selected while a process is performed and must be shifted to the apparatus so that analysis can be conducted. Additional time must be taken in order to inspect the entire substrate (thorough inspection). In this case, curtailment of productivity must be endured. Therefore, it is the custom that the entire substrate is not inspected while a process is performed.

Disclosure of Invention Technical Problem

[6] However, the conventional apparatus is a separate apparatus that is spaced apart from a process apparatus in which unit processes are performed, and thus, part of the substrate must be selected while a process is performed and must be shifted to the apparatus so that analysis can be conducted. When the entire substrate is inspected (thorough inspection), an additional time required for thorough inspection must be taken. In this case, curtailment of productivity must be endured. Therefore, it is the custom that the entire substrate is not inspected while a process is performed. Technical Solution

[7] The present invention provides a process method for measuring substrate warpage after each process is completed using in-line and thorough inspection so as to easily and quickly determine whether each operation of a semiconductor device fabricating process is performed within standard requirements, a recording medium in which a program for executing the process method is recorded, and a process apparatus for performing the process method.

Advantageous Effects

[8] According to the present invention, a substrate curvature measuring unit is not installed in a separate space within a clean room but is disposed on a substrate transfer path between a process apparatus and a process apparatus or between a substrate carrier and a substrate carrier or within a buffer chamber of a multi-chamber type process apparatus such that an additional space for the clean room and a curvature measuring time are not needed. Also, since curvatures of all substrates are automatically measured, data of the measured curvatures of the substrates is utilized such that an improvement in yield can be achieved by statistical process control utilizing a vast amount of measuring data. Thus, precise control of a semiconductor process can be performed. Brief Description of the Drawings

[9] The above and other aspects of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

[10] FIG. 1 illustrates a process method according to an embodiment of the present invention;

[11] FIG. 2 illustrates a modified example of the process method shown in FIG. 1;

[12] FIG. 3 is a plan view of a multi-chamber type process apparatus according to an embodiment of the present invention, so as to explain a process method according to another embodiment of the present invention; and

[13] FIG. 4 illustrates a process method according to another embodiment of the present invention. Best Mode for Carrying Out the Invention

[14] The curvature measuring unit may be installed between two substrate carriers or between two process apparatuses or within a buffer chamber in a multi-chamber type process apparatus. Here, the buffer chamber means a buffer chamber in a multi- chamber type process apparatus in which the buffer chamber is installed between one or more load-lock chambers and one or more process chambers.

[15] When measured warpage of the substrate is not within an allowable range, the substrate may be rejected or may be continuously monitored.

[16] The process method may be stored in a computer readable recording medium having software recorded thereon, and may be performed by a widely-used computer system.

[17] According to another aspect of the present invention, there is provided a multi- chamber type process apparatus in which a buffer chamber is installed between one or more load-lock chambers and one or more process chambers, wherein a curvature measuring unit is placed on a transfer path of the substrate within the buffer chamber to measure warpage of the substrate in real-time while the substrate is transferred.

[18] The curvature measuring unit may be placed on each transfer path to the one or more process chambers. The buffer chamber may use one of a robot method, a track method, and a combination thereof when loading/unloading and transferring the substrate. [19] According to the present invention, in order to improve yield of a semiconductor process, a curvature measuring unit for measuring warpage of a substrate which reflects a change in process is disposed on a substrate transfer path. For example, a curvature measuring unit for measuring warpage of the substrate is placed on a path on which the substrate is transferred between a conventional semiconductor process apparatus and a process apparatus so that the substrate can be transferred and simultaneously, the curvature of the substrate can be measured and warpage can be measured. As such, the whole substrate in process can be inspected using an in-line method without using an additional space within a clean room, and without additional burden of a measuring time so that, in view of process control, data for more precise control can be provided. Mode for the Invention

[20] The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, relative positions or sizes of elements are exaggerated for clarity. Like reference numerals in the drawings denote like elements, and thus their description will be omitted.

[21] In the present invention, "substrate" may indicate a semiconductor wafer or an oxide- based substrate etc. For example, the semiconductor wafer may be a Si, GaAs, InP, SiC, GaN substrate. The oxide-based substrate may be a substrate formed of sapphire (Al₂O₃) or quartz (SiO₂), and the substrate may be crystalline or amorphous.

[22] In a process method according to the present invention, a curvature measuring unit is installed on "a transfer path of a substrate within a clean room", and substrate warpage is measured while the substrate is transferred in real-time. Here, "the transfer path of the substrate within the clean room" may be classified into three, i.e., a transfer path between two process apparatuses, a transfer path from a multi-chamber type process apparatus to a buffer chamber, and a transfer path between two substrate carriers. Hereinafter, each transfer path will be described in detail.

[23] FIG. 1 illustrates a process method according to an embodiment of the present invention, and FIG. 2 illustrates a modified example of the process method shown in FIG. 1.

[24] Referring to FIG. 1, when a process of a substrate W is performed using two process apparatuses 10 and 20 sequentially within a clean room, a curvature measuring unit 40 is installed on a transfer path 30 of the substrate W, and while the substrate W is transferred from a process apparatus 10 to a next process apparatus 20, warpage of the substrate W is measured in real-time.

[25] When a vast amount of measuring data obtained by the process method is processed, a value of an allowable range in which a normal curvature in a process is known is obtained. When warpage of the measured substrate W is not within an allowable range, it is preferable that the substrate W is rejected and a process proceeding is not performed any more or the substrate W is continuously monitored and a change of the substrate W is observed.

[26] When measured warpage of the substrate W is not within the allowable range, a process method by which the substrate W is rejected or is continuously monitored may be stored in a computer readable recording medium having software recorded thereon, and may be performed by a widely-used computer system. Thus, the process method is performed by a digital computer that is generally connected to a process apparatus within a clean room so that the present invention can be more easily embodied. Examples of the computer readable recording medium include recording mediums such as read-only memory (ROM) or flash memory, and magnetic recording mediums (such as floppy disks or hard disks etc.), optical recording mediums (such as CD- ROMs or DVD etc.), and carrier waves (such as the Internet). Here, functional programs, codes, and code segments for coding each program module of computer software can be easily construed by programmers of ordinary skill in the art to which the present invention pertains.

[27] The curvature measuring unit 40 is aligned in a direction perpendicular to a surface of the substrate W, so as to see the front side of the substrate W. Since there are many cases where the substrate W is transferred while being maintained in a horizontal direction on the ground, the curvature measuring unit 40 is located in a direction perpendicular to a surface that is defined by movement of the substrate W. The curvature measuring unit 40 may mainly use not only optical methods such as using laser multi- beams but also other methods. In optical methods, a curvature radius is measured using laser multi-beams on the substrate W. On the other hand, it should be noted that the type of the substrate W is not limited to the previously-mentioned types. Transferring of the substrate W between two process apparatuses 10 and 20 may be conducted using a robot method, a track method or a combination thereof. For example, a transfer robot may transfer the substrate W from the process apparatus 10 to the process apparatus 20 or the transfer robot may load/unload the substrate W on/from a substrate carrier and a track may be used when the substrate W is transferred. Even though the substrate W is transferred using any method, installing of the curvature measuring unit on the transfer path of the substrate W to perform thorough inspection may correspond to the present invention.

[28] In the present embodiment of the present invention, the curvature measuring unit 40 measures warpage of the substrate W after unit processes in the process apparatus 10 while the substrate W is transferred to next process apparatus 20. Thus, warpage of the substrate W can be measured using an in-line method without using an additional space within a clean room or using thorough inspection of the substrate W in process without additional burden of a measuring time so that, in view of process control, data for more precise control can be provided.

[29] As a modified example, when the substrate W is processed using three or more apparatuses, as illustrated in FIG. 2, a curvature measuring unit is installed between two adjacent process apparatuses so that warpage of the substrate W after each process can be measured. In FIG. 2, reference numeral "50" denotes an added process apparatus compared to FIG. 1, and reference numeral "60" denotes an added curvature measuring unit. As described above, the curvature measuring unit 40 measures warpage of the substrate W after unit process in the process apparatus 10 while the substrate W is transferred to next process apparatus 20, and the curvature measuring unit 60 measures warpage of the substrate W after unit process in the process apparatus 20 while the substrate W is transferred to next process apparatus 50. Thus, warpage of the substrate W after each process is performed can be measured.

[30] FIG. 3 is a plan view of a multi-chamber type process apparatus according to an embodiment of the present invention, so as to explain a process method according to another embodiment of the present invention. In general, a multi-chamber system in which substrate processing works are simultaneously performed in a plurality of chambers so as to enhance process efficiency and space utility is adopted in a semiconductor device fabricating process.

[31] Referring to FIG. 3, a multi-chamber type process apparatus 100 according to an embodiment of the present invention includes four process chambers 120a, 120b, 120c, and 12Od that are connected to angled sides of a hexagonal buffer chamber 110.

[32] A vacuum forming device (not shown) is installed in the process chambers 120a,

120b, 120c, and 12Od and the buffer chamber 110. The process chambers 120a, 120b, 120c, and 12Od are in a vacuum state that is suitable for processing such as thin layer deposition, and the buffer chamber 110 is maintained in a vacuum state for reducing a vacuum pressure loss of the process chambers 120a, 120b, 120c, and 12Od. A transfer robot 115 installed in the buffer chamber 110 loads/unloads the substrate W on/from each of the process chambers 120a, 120b, 120c, and 12Od selectively through a slit- shaped gate (not shown) installed between the buffer chamber 110 and each of the process chambers 120a, 120b, 120c, and 12Od. A carry-in load-lock chamber 125 on which the substrate W before processing is stacked, and a carry-out load-lock chamber 127 on which the substrate W after processing is stacked, are installed at the other angled sides of the buffer chamber 110, respectively. The carry-in load-lock chamber 125 is an intermediate standby place of the substrate W in which the environment of the substrate W is changed into a vacuum state from an atmospheric pressure, and the carry-out load-lock chamber 127 is an intermediate standby place of the substrate W in which the environment of the substrate W is changed into an atmospheric pressure from a vacuum state.

[33] The multi-chamber type process apparatus 100 of FIG. 3 includes curvature measuring units 140a, 140b, 140c, and 14Od on transfer paths 130a, 130b, 130c, and 130d to the process chambers 120a, 120b, 120c, and 12Od within the buffer chamber 110, respectively. The curvature measuring units 140a, 140b, 140c, and 14Od measure warpage of the substrate W in real-time while the substrate W is transferred to the process chambers 120a, 120b, 120c, and 12Od within the buffer chamber 110 and while the substrate W is transferred to the buffer chamber 110 from the process chambers 120a, 120b, 120c, and 12Od. In other words, warpage of the substrate W before and after each process can be measured using each of the curvature measuring units 140a, 140b, 140c, and 14Od. As described above, when measured warpage of the substrate W is not within an allowable range, it is preferable that the substrate W is rejected or is continuously monitored. The process method may be stored in a computer readable recording medium having software recorded thereon, and may be performed by a widely-used computer system.

[34] Specifically, a worker or an automatic transfer device installed inside the carry-in load-lock chamber 125 transfers the substrate W stacked on a substrate cassette or in a substrate carrier such as a front open unified pod (FOUP) to the carry-in load-lock chamber 125. After the carry-in load- lock chamber 125 is sealed and reaches a vacuum state, the substrate W is shifted to the transfer robot 115 installed in the buffer chamber 110, and the transfer robot 115 transfers the substrate W to one of the process chambers 120a, 120b, 120c, and 12Od. For example, when the substrate W is transferred to the process chamber 120a, warpage of the substrate W before process can be measured using the curvature measuring unit 140a. When the substrate W is transferred into the process chambers 120a, 120b, 120c, and 120c, the gate is sealed and then, a process is performed in a high vacuum state. The substrate W in which the process is completed is adversely transferred by the transfer robot 115 and is stacked on the carry-out lock-lock chamber 127. For example, when the substrate W is transferred from the process chamber 120, warpage of the substrate W after process can be measured using the curvature measuring unit 140a.

[35] In this way, when the curvature measuring units 140a, 140b, 140c, and 14Od are placed on the substrate transfer paths 130a, 130b, 130c, and 130d within the buffer chamber 110, a change in substrate warpage before and after processes with respect to all substrates may be measured without an additional space of a clean room and an additional measuring time for measuring curvature so that data for process control can be obtained with respect to all substrates.

[36] On the other hand, in the present embodiment of the present invention, the case where one of the curvature measuring units 140a, 140b, 140c, and 14Od is placed on each of the substrate transfer paths 130a, 130b, 130c, and 130d on which the transfer robot 115 moves, so as to cause no time delay, is illustrated. However, an apparatus in which one curvature measuring unit is placed in the center of the buffer chamber 110 and a transfer path is adjusted so that all substrates pass a lower portion of the curvature measuring unit, may also be provided. In the present embodiment of the present invention, the buffer chamber 110 uses a robot method when loading/unloading and transferring the substrate W. However, the buffer chamber 110 may also use a track method or a combination of the robot method and the track method.

[37] On the other hand, in the present embodiment of the present invention, the case where a pair of load-lock chambers such as a carry-in load-lock chamber and a carry- out load-lock chamber is provided and four process chambers are provided has been described. However, only one load-lock chamber may be provided for carry- in/carry-out, and the number of process chambers connected to the buffer chamber may be different. In addition, an apparatus in which two or more buffer chambers are provided and one or more process chambers are connected to each of the buffer chambers may be provided.

[38] FIG. 4 illustrates a process method according to another embodiment of the present invention.

[39] Referring to FIG. 4, this case is not the case where the substrate W is not transferred between process apparatuses within a clean room but the case where the substrate W is transferred between two substrate carriers 200 and 210 such as between a cassette and a cassette or between a FOUP and a FOUP. A curvature measuring unit 230 is installed on a transfer path 220 on which the substrate W is transferred from the substrate carrier 200 to the substrate carrier 210 using a robot and/or a track, so that warpage of the substrate W can be measured in real-time while the substrate W is transferred and can be used in statistical process control. Even here, when warpage of the substrate W is not within an allowable range, it is preferable that the substrate W is rejected or is continuously monitored.

[40] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. Industrial Applicability

[41] Since curvature measurement is performed automatically with respect to all substrates, curvature measurement data about all substrates is utilized such that improvement in yield is expected by statistical process control utilizing a vast amount of measuring data. Thus, precise control of a semiconductor process can be performed.

Claims

[1] A process method comprising: installing a curvature measuring unit on a transfer path of a substrate within a clean room; and measuring warpage of the substrate in real-time while the substrate is transferred. [2] The process method of claim 1, wherein the curvature measuring unit is installed between two process apparatuses. [3] The process method of claim 1, wherein the curvature measuring unit is installed within a buffer chamber in a multi-chamber type process apparatus in which the buffer chamber is installed between one or more load-lock chambers and one or more process chambers. [4] The process method of claim 1, wherein the curvature measuring unit is installed between two substrate carriers. [5] The process method of one of claims 1 through 4, wherein, when measured warpage of the substrate is not within an allowable range, the substrate is rejected or is continuously monitored. [6] A computer readable storage medium in which computer software for performing management of the process method of claim 1 is stored, when the process method of claim 1 is performed by a widely-used computer system, the computer readable storage medium comprising, when measured warpage of the substrate is not within an allowable range, rejecting the substrate or monitoring the substrate continuously. [7] A multi-chamber type process apparatus in which a buffer chamber is installed between one or more load-lock chambers and one or more process chambers, wherein a curvature measuring unit is placed on a transfer path of the substrate within the buffer chamber to measure warpage of the substrate in real-time while the substrate is transferred. [8] The multi-chamber type process apparatus of claim 7, wherein the curvature measuring unit is placed on each transfer path to the one or more process chambers. [9] The multi-chamber type process apparatus of claim 7, wherein the buffer chamber uses one of a robot method, a track method, and a combination thereof when loading/unloading and transferring the substrate. [10] The multi-chamber type process chamber of one of claims 7 through 9, wherein, when measured warpage of the substrate is not within an allowable range, the substrate is rejected or is continuously monitored.