JP2008117964A - Reflow method, pattern forming method and manufacturing method of tft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save a resist and reduce the number of processes, the total processing time and the number of lithography-related apparatuses while ensuring the uniformity of the accuracy of patterns in an object to be treated. <P>SOLUTION: Prior to reflow treatment in step S7, surface reforming treatment is executed in a step S6. The exposed surface of an n<SP>+</SP>Si film 205 is reformed by the surface reforming treatment, and a surface-reformed treatment surface 205a is formed. Then, reflow treatment is performed in a reflow treatment unit (REFLW) 60. While deforming a softened resist, the reflow treatment can suppress the fluidization of the softened resist on the surface-reformed treatment surface 205a of the n<SP>+</SP>Si film 205, and remarkably suppress a phenomenon that the deformed resist 212 after reflow overflows to the surrounding exceeding areas of source and drain electrodes 206a, 206b of a lower layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resist reflow method that can be used in a manufacturing process of a thin film transistor (TFT), for example, a pattern formation method using the method, and a TFT manufacturing method.

  An active matrix type liquid crystal display device supports liquid crystal sandwiched between a TFT substrate on which a thin film transistor (TFT) is formed and a counter substrate on which a color filter is formed so that a voltage can be selectively applied to each pixel. It is configured. In the process of manufacturing the TFT substrate used here, a resist mask is necessary for each photolithography process because patterning of a photosensitive material such as a resist is repeatedly performed by a photolithography technique.

  However, in recent years, with the progress of high integration and miniaturization of liquid crystal display devices, the manufacturing process has become complicated, and the manufacturing cost tends to increase. Therefore, in order to reduce the manufacturing cost, it has been studied to integrate the mask pattern forming process for photolithography to reduce the total number of processes. For example, a halftone mask with a difference in light transmittance is used as an exposure mask, and so-called half exposure processing is performed to pattern resist masks with different film thicknesses in a single exposure process. (For example, Patent Documents 1 and 2).

  An example of a manufacturing procedure of a TFT substrate using such a half exposure technique is as follows. For example, an insulating film, an amorphous silicon film, an ohmic contact film, and a metal film are stacked so as to cover the gate electrode formed on the glass substrate. Thereafter, a pattern is formed by a half exposure process so that the resist film thickness corresponding to the channel region is reduced, and metal film etching and silicon etching (etching of ohmic contact film and amorphous silicon film) are performed.

  Thereafter, for example, ashing or redevelopment processing is performed to reduce the thickness of the resist as a whole, whereby the thin film portion of the resist is removed to expose a portion of the metal film corresponding to the channel region. Then, the exposed metal film is etched to form a source electrode and a drain electrode, and the ohmic contact film is further etched to expose the semiconductor film in the channel region to form a TFT element. Then, after removing the resist, an organic film made of a photosensitive material is deposited on the TFT element, and a pattern is formed by a photolithography technique to form a contact hole. Further, a conductive film such as indium tin oxide (ITO) is formed on the organic film, and the transparent film is formed by etching the conductive film using a resist patterned by a photolithography technique as a mask. A TFT substrate is formed.

In the above-described process, by using the half exposure technique, a silicon etching mask and an etching mask for forming the source electrode and the drain electrode can be formed in one photolithography process. Accordingly, the number of resist film formations is reduced, and the amount of resist used can be reduced.
Japanese Patent Laid-Open No. 9-80740 (claims, etc.) JP-A-2005-108904 (Claims etc.)

  In manufacturing a TFT substrate using the half exposure process, it is possible to reduce the number of resists and reduce the number of photolithography processes. On the other hand, however, when the half exposure technique is used, ashing or redevelopment processing is required to reduce the film thickness of the resist as a whole and remove the thin film portion. When the thin film portion of the resist is removed by performing ashing, there is a problem that it is difficult to ensure the uniformity of the pattern accuracy within the substrate surface. In addition, since the redevelopment process is a liquid process involving the application of a developer, the process flow is complicated in that separate liquid processes of the development process and the redevelopment process are repeated, resulting in a reduction in apparatus costs and running costs. In order to secure the accuracy of the re-development treatment, it is necessary to perform a pretreatment for removing the surface alteration layer of the resist in advance, and there is a problem that there is a limit in reducing the number of steps.

  Therefore, the present invention provides a reflow method capable of reducing the number of processes, the total process time, and the number of photolithography-related apparatuses and mask pattern formation while ensuring the accuracy of the mask pattern on the object to be processed. It is an object to provide a method and a method for manufacturing a TFT.

  In order to solve the above problems, a first aspect of the present invention is to form a lower layer film, an exposed region in which the lower layer film is exposed above the lower layer film, and a covered region in which the lower layer film is coated. And subjecting the object to be processed having a patterned film to a surface modification treatment so that the flow of the resist is suppressed in the exposed region of the lower layer film, and then the resist of the resist film is removed. A reflow method is provided in which the exposed area is partially covered by softening and flowing.

According to a second aspect of the present invention, a resist film forming step of forming a resist film in an upper layer than an etching target film of an object to be processed;
An exposure process for exposing the resist film;
A patterning step of developing the exposed resist film to form a resist pattern;
A reflow step of softening and deforming the resist of the resist film and covering a target region of the film to be etched;
A first etching step of etching an exposed region of the etching target film using the deformed resist as a mask;
Removing the resist after deformation;
A second etching step of etching the target region of the film to be etched that is reexposed by removing the resist after the deformation;
Including
Provided is a pattern forming method including a step of performing a surface modification process on the exposed region in advance so as to suppress the flow of the softened resist prior to the reflow step.

According to a third aspect of the present invention, a step of forming a gate electrode on a substrate;
Forming a gate insulating film covering the gate electrode;
Depositing an a-Si film, an ohmic contact Si film, and a source / drain metal film in order from the bottom on the gate insulating film;
Forming a resist film on the source / drain metal film;
Exposing the resist film using a predetermined exposure mask; and
A mask patterning step of developing and patterning the exposed resist film to form a resist mask for a source electrode and a resist mask for a drain electrode;
A metal film etching step of etching the source / drain metal film using the source electrode resist mask and the drain electrode resist mask as a mask to form a source electrode and a drain electrode;
A surface modification step of performing a surface modification process on the exposed region of the ohmic contact Si film not covered with the source electrode and the drain electrode so that the flow of the resist is suppressed;
An organic solvent is allowed to act on the resist mask for the source electrode and the resist mask for the drain electrode to soften and deform the resist, thereby at least the ohmic in the recess for the channel region between the source electrode and the drain electrode. A reflow process of covering the contact Si film with a deformed resist;
Etching the lower ohmic contact Si film and the a-Si film using the resist after deformation and the source and drain electrodes as a mask;
Removing the deformed resist and exposing the ohmic contact Si film again in the recess for the channel region between the source electrode and the drain electrode;
Etching the ohmic contact Si film exposed in the recess for the channel region between the source electrode and the drain electrode as a mask;
The manufacturing method of TFT containing this is provided.

A fourth aspect of the present invention is a computer-readable storage medium storing a control program that runs on a computer,
The control program provides a computer-readable storage medium that controls the reflow processing system so that the reflow method of the first aspect is performed at the time of execution.

According to a fifth aspect of the present invention, there is provided a surface modification processing unit that performs surface modification processing on an object to be processed.
A reflow processing unit for softening and fluidizing the resist on the target object after the surface modification treatment in a solvent atmosphere;
A control unit that controls the reflow method of the first aspect to be performed in the processing chamber;
A reflow processing system is provided.

According to the present invention, prior to the reflow process, the exposed surface of the lower layer film is subjected to a surface modification process in advance so that the flow of the softened resist is suppressed, thereby effectively suppressing the spread of the resist in the reflow process. it can. This makes it possible to adjust the area of the base film that is fluidized by the reflow process and is covered with the deformed resist.
Therefore, by applying the reflow method of the present invention to the manufacture of a semiconductor device such as a TFT element in which an etching process using a resist as a mask is repeatedly performed, high etching accuracy can be ensured, and the semiconductor device can be highly integrated. It is possible to cope with miniaturization. Further, it is possible to reduce the number of resists and reduce the number of photolithography processes without requiring half exposure processing or re-development processing.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic plan view showing the entire reflow processing system that can be suitably used in the reflow method of the present invention. Here, the resist film formed on the surface of the LCD glass substrate (hereinafter simply referred to as “substrate”) G is softened and deformed after the development process, and is reused as an etching mask when etching the lower layer film. For example, a reflow processing system including a reflow processing unit that performs the reflow processing for the purpose and an adhesion unit that performs surface modification processing prior to the reflow processing will be described. The reflow processing system 100 is configured to transfer the substrate G to / from an external resist coating / development processing system, an exposure apparatus, an etching apparatus, an ashing apparatus, etc. via a substrate transfer line (not shown). Yes.

  The reflow processing system 100 includes a series of processing including a cassette station (loading / unloading unit) 1 on which a cassette C that accommodates a plurality of substrates G is placed, a reflow processing on the substrate G, and a surface modification process that is performed prior to this. A processing station (processing unit) 2 including a plurality of processing units for performing processing, and a control unit 3 that controls each component of the reflow processing system 100 are provided. In FIG. 1, the longitudinal direction of the reflow processing system 100 is the X direction, and the direction orthogonal to the X direction on the horizontal plane is the Y direction.

  The cassette station 1 is disposed adjacent to one end of the processing station 2. The cassette station 1 includes a transfer device 11 for carrying in and out the substrate G between the cassette C and the processing station 2, and the cassette C is carried into and out of the cassette station 1. Further, the transport device 11 includes a transport arm 11a that can move on a transport path 10 provided along the Y direction that is the arrangement direction of the cassettes C. The transfer arm 11 a is provided so as to be able to advance, retreat and rotate in the X direction, and is configured so that the substrate G can be transferred between the cassette C and the processing station 2.

  The processing station 2 includes a plurality of processing units for performing a resist reflow process on the substrate G and a surface modification process as a pre-process. In each of these processing units, the substrate G is processed one by one. Further, the processing station 2 has a central transport path 20 for transporting the substrate G that basically extends in the X direction, and each processing unit is placed on both sides of the central transport path 20 with the central transport path 20 interposed therebetween. It is arranged to face 20.

  Further, the central transport path 20 is provided with a transport device 21 for loading and unloading the substrate G to and from each processing unit, and a transport arm 21a movable in the X direction that is the arrangement direction of the processing units. have. Further, the transfer arm 21a is provided so as to be advanced / retracted in the Y direction, moved up / down in the vertical direction, and rotated, and is configured to be able to carry in / out the substrate G to / from each processing unit. Yes.

  On one side along the central transport path 20 of the processing station 2, an adhesion unit (AD) 30 and a reflow processing unit (REFLW) 60 are arranged in this order from the cassette station 1 side. On the other side, three heating / cooling processing units (HP / COL) 80a, 80b, 80c are arranged in a line. The heating / cooling processing units (HP / COL) 80a, 80b, and 80c are stacked in multiple layers in the vertical direction (not shown).

  Adhesion unit (AD) 30 is a surface modification treatment agent represented by a silylating agent such as HMDS (hexamethyldisilazane) or TMSDEA (N-trimethylsilyldiethylamine) for substrate G prior to the reflow treatment. A surface modification treatment is performed to promote the flow of the resist. These surface modification treatment agents have a hydrophobization treatment action and are also known as hydrophobization treatment agents.

Here, the adhesion unit (AD) 30 will be described with reference to FIG.
The adhesion unit (AD) 30 has a rectangular parallelepiped frame (not shown), and has a fixed chamber main body 31 and a lid 33 that can be moved up and down inside the frame. The chamber body 31 is configured as a flat rectangular parallelepiped lower container that is one size larger than the substrate G and has an upper surface opened.

  The lid 33 is configured as a flat rectangular parallelepiped upper container opened on the lower surface of substantially the same size (area) as the chamber body 31, and is connected to an HMDS supply source 35 for storing HMDS used for surface modification, as will be described later. ing. Further, the lid 33 is fixed to a plurality of horizontal support members 37 extending in the horizontal direction (X direction and Y direction), and each horizontal support member 37 is a lifting drive mechanism (not shown) such as a plurality of air cylinders. It is connected to the piston rod. Accordingly, when the piston rods of these air cylinders are advanced vertically upward, the lid 33 is moved upward (raised) integrally with the horizontal support member 37 to open the chamber. When the piston rod is retracted vertically downward, the lid 33 moves (lowers) vertically downward integrally with the horizontal support member 37.

  In the chamber body 31, a rectangular heating plate 41 having a size substantially corresponding to the substrate G is horizontally disposed and fixed by a fixture 42. The heating plate 41 is made of a metal having a high thermal conductivity such as aluminum, and a heater (not shown) made of a resistance heating element is provided inside or on the lower surface thereof.

  In addition, a plurality of through holes 43 are formed in the heating plate 41, lifter pins 44 are inserted into the respective through holes 43, and a substrate lifting mechanism 45 that lifts the substrate G up and down is provided. . These lifter pins 44 project from the surface of the heating plate 41 so as to deliver the substrate G to and from the transfer arm 21a (see FIG. 1) of the external transfer device 21. The lifter pins 44 are connected to each other by a horizontal support plate 46 disposed under the heating plate 41 and configured to be able to move up and down in synchronization. A lifting drive unit (not shown) for moving the horizontal support plate 46 up and down is disposed inside or outside the chamber body 31.

  A seamless seal member 32 extending in the circumferential direction is attached to the upper end surface of the side wall of the chamber body 31. The sealing member 32 is interposed between the lower end surface of the side wall of the lid body 33 and the upper end surface of the side wall of the chamber body 31 in a state in which the lid body 33 is combined with the chamber main body 31 so as to be sealed. Thereby, an airtight processing chamber 47 is formed by the chamber body 31 and the lid 33.

An HMDS gas introduction port 48 is provided on one side surface of the lid 33, and an exhaust port 49 is provided on the other side surface facing the HMDS gas introduction port 48.
The HMDS gas introduction port 48 includes a plurality of through holes 50 formed at an arbitrary interval on one side surface of the lid 33, a terminal adapter 53 of a gas supply pipe 51 attached to each through hole 50 from the outside, The buffer chamber 54 is provided inside the through hole 50 and has a number of gas discharge ports 55 formed at regular intervals.

  The exhaust port 49 has a large number of vent holes 56 formed at regular intervals on the side surface of the lid 33 facing the HMDS gas introduction port 48 and an exhaust duct chamber provided outside the side wall of the lid 33. 57. An exhaust port 58 formed at the bottom of the exhaust duct chamber 57 is connected to an exhaust pump (not shown) through an exhaust pipe 59.

  When the surface modification process is performed in the adhesion unit (AD) 30 having such a configuration, first, the substrate G is removed from the transfer arm 21a of the transfer device 21 with the lifter pin 44 of the substrate lifting mechanism 45 raised. Receive. Then, after the lifter pin 44 is lowered and the substrate G is placed on the heating plate 41, the lid 33 is vertically lowered from the retracted position and brought into contact with the chamber body 31 to seal the chamber. The substrate G is heated to a predetermined temperature, for example, 110 ° C. to 120 ° C. by the heating plate 41. Then, the HMDS gas is supplied from the HMDS supply source 35 to the processing chamber 47 through the gas supply pipe 51 and the HMDS gas introduction port 48 while exhausting the processing chamber 47 by an exhaust pump (not shown). In the processing chamber 47, the HMDS gas ejected from the gas discharge port 55 of the HMDS gas introduction port 48 forms an air flow toward the exhaust port 49, and contacts the surface (surface to be processed) of the substrate G in the middle thereof. The surface is surface-modified.

  The HMDS gas that has passed through the processing chamber 47 is sent from the vent hole 56 to the exhaust duct chamber 57 at the exhaust port 49 and is exhausted therefrom by the action of the exhaust pump. After a predetermined processing time has elapsed and the surface modification process is completed, the supply of the HMDS gas and the exhaust pump are stopped, and then the lid 33 is moved upward from the chamber body 31 by the ascending drive of a lifting drive mechanism (not shown). Pull it up and lift it up to a predetermined retracted position. Thereafter, the lifter pin 44 of the substrate lifting mechanism 45 is raised, the substrate G is lifted above the heating plate 41, and transferred to the transport arm 21 a of the transport device 21. Thereafter, the substrate G after the surface modification treatment is unloaded from the adhesion unit (AD) 30 by the transfer arm 21a.

  Next, the substrate G after the surface modification treatment is carried into the reflow processing unit (REFLW) 60 of the processing station 2 by the transfer arm 21a, and the resist formed on the substrate G is softened in an organic solvent such as a thinner atmosphere. A reflow process for changing the mask shape is performed.

  Here, the configuration of the reflow processing unit (REFLW) 60 will be described in more detail. FIG. 3 is a schematic sectional view of the reflow processing unit (REFLW) 60. The reflow processing unit (REFLW) 60 includes a chamber 61, and the chamber 61 includes a lower chamber 61a and an upper chamber 61b that comes into contact with the upper portion of the lower chamber 61a. The upper chamber 61b and the lower chamber 61a are configured to be opened and closed by an opening / closing mechanism (not shown), and the substrate G is carried in / out by the transfer device 21 in the open state.

  A support table 62 that supports the substrate G horizontally is provided in the chamber 61. The support table 62 is made of a material having excellent thermal conductivity, for example, aluminum.

  The support table 62 is provided with three elevating pins 63 (only two are shown in FIG. 3) that are driven by an elevating mechanism (not shown) to raise and lower the substrate G so as to penetrate the support table 62. . The lift pins 63 lift the substrate G from the support table 62 and support the substrate G at a predetermined height when transferring the substrate G between the lift pins 63 and the transfer device 21. During the reflow process, for example, the tip is held so as to be at the same height as the upper surface of the support table 62.

  Exhaust ports 64a and 64b are formed at the bottom of the lower chamber 61a, and an exhaust system 64 is connected to the exhaust ports 64a and 64b. The atmospheric gas in the chamber 61 is exhausted through the exhaust system 64.

  A temperature adjustment medium flow path 65 is provided inside the support table 62, and a temperature adjustment medium such as temperature-controlled cooling water is provided in the temperature adjustment medium flow path 65 via a temperature adjustment medium introduction pipe 65a. It is introduced and discharged from the temperature control medium discharge pipe 65b and circulated, and its heat (for example, cold heat) is transferred to the substrate G through the support table 62, whereby the processing surface of the substrate G reaches a desired temperature. Be controlled.

  A shower head 66 is provided on the top wall portion of the chamber 61 so as to face the support table 62. A large number of gas discharge holes 66 b are provided on the lower surface 66 a of the shower head 66.

A gas introduction part 67 is provided at the upper center of the shower head 66, and the gas introduction part 67 communicates with a space 68 formed in the shower head 66. A pipe 69 is connected to the gas introduction part 67. A bubbler tank 70 for vaporizing and supplying an organic solvent such as thinner is connected to the pipe 69, and an open / close valve 71 is provided in the middle thereof. An N ₂ gas supply pipe 74 connected to an N ₂ gas supply source (not shown) is provided at the bottom of the bubbler tank 70 as a bubble generating means for vaporizing the thinner. The N ₂ gas supply pipe 74 is provided with a mass flow controller 72 and an opening / closing valve 73. The bubbler tank 70 includes a temperature adjusting mechanism (not shown) for adjusting the temperature of the thinner stored therein to a predetermined temperature. Then, by introducing N ₂ gas from a N ₂ gas supply source (not shown) to the bottom of the bubbler tank 70 while controlling the flow rate by the mass flow controller 72, the thinner in the bubbler tank 70 adjusted to a predetermined temperature is vaporized, It can be introduced into the chamber 61 via a pipe 69 and a gas introduction part 67.

Further, a plurality of purge gas introduction portions 75 are provided at the peripheral edge of the upper portion of the shower head 66, and each purge gas introduction portion 75 has a purge gas supply pipe for supplying, for example, N ₂ gas as a purge gas into the chamber 61. 76 is connected. The purge gas supply pipe 76 is connected to a purge gas supply source (not shown), and an opening / closing valve 77 is provided in the middle thereof.

  In the reflow processing unit (REFLW) 60 having such a configuration, first, the upper chamber 61b is opened from the lower chamber 61a, and in this state, the pattern is already formed by the transfer arm 21a of the transfer device 21, and the surface modification process is performed. The substrate G having the resist subjected to the above is carried in and placed on the support table 62. Then, the upper chamber 61b and the lower chamber 61a are brought into contact with each other, and the chamber 61 is closed.

Next, the open / close valve 71 of the pipe 69 and the open / close valve 73 of the N ₂ gas supply pipe 74 are opened, and the mass flow controller 72 adjusts the flow rate of N ₂ gas to control the vaporization amount of the thinner. The vaporized thinner is introduced into the space 68 of the shower head 66 through the pipe 69 and the gas introduction part 67 and discharged from the gas discharge hole 66b. Thereby, the inside of the chamber 61 is made into a thinner atmosphere having a predetermined concentration.

  Since the patterned resist is already provided on the substrate G placed on the support table 62 in the chamber 61, the resist permeates the resist when the resist is exposed to the thinner atmosphere. As a result, the resist is softened to increase its fluidity and deform to cover a predetermined region (target region) on the surface of the substrate G with the deformed resist. At this time, by introducing the temperature adjustment medium into the temperature adjustment medium flow path 65 provided inside the support table 62, the heat is transferred to the substrate G through the support table 62. The processing surface of G is controlled to a desired temperature, for example, 20 ° C. The gas containing the thinner discharged from the shower head 66 toward the surface of the substrate G contacts the surface of the substrate G, then flows toward the exhaust ports 64a and 64b, and is exhausted from the chamber 61 to the exhaust system 64. .

After the reflow processing in the reflow processing unit (REFLW) 60 is completed as described above, the open / close valve 77 on the purge gas supply pipe 76 is opened while continuing the exhaust, and the chamber 61 is opened via the purge gas introduction unit 75. N ₂ gas as a purge gas is introduced to replace the atmosphere in the chamber. Thereafter, the upper chamber 61b is opened from the lower chamber 61a, and the substrate G after the reflow process is carried out from the reflow process unit (REFLW) 60 by the transfer arm 21a in the reverse procedure.

  The three heating / cooling processing units (HP / COL) 80a, 80b, and 80c include a hot plate unit (HP) that heats the substrate G and a cooling plate unit (cooling plate unit that cools the substrate G). COL) is configured to be stacked in multiple stages, for example, two stages, for a total of four stages (not shown). In the heating / cooling processing units (HP / COL) 80a, 80b, 80c, the substrate G after the surface modification processing and the reflow processing is subjected to heating processing and cooling processing as necessary.

  As shown in FIG. 1, each component of the reflow processing system 100 is connected to and controlled by a controller 90 having a CPU of the controller 3. Connected to the controller 90 is a user interface 91 including a keyboard for a process manager to input a command to manage the reflow processing system 100, a display for visualizing and displaying the operating status of the reflow processing system 100, and the like. Has been.

  The controller 90 is connected to a storage unit 92 that stores a recipe in which a control program and processing condition data for realizing various processes executed by the reflow processing system 100 are controlled by the controller 90. ing.

  Then, if necessary, an arbitrary recipe is called from the storage unit 92 by an instruction from the user interface 91 and is executed by the controller 90, so that a desired process in the reflow processing system 100 is controlled under the control of the controller 90. Is done. The recipe may be stored in a computer-readable storage medium such as a CD-ROM, a hard disk, a flexible disk, or a flash memory, or may be a dedicated line from another device. It is also possible to transmit and use it as needed.

  In the reflow processing system 100 configured as described above, first, in the cassette station 1, the transfer arm 11a of the transfer apparatus 11 accesses the cassette C that contains the substrate G on which the resist pattern is already formed. One substrate G is taken out. The substrate G is transferred from the transfer arm 11a of the transfer device 11 to the transfer arm 21a of the transfer device 21 in the central transfer path 20 of the processing station 2, and is transferred into the adhesion unit (AD) 30 by the transfer device 21. The Then, after the surface modification process is performed prior to the reflow process in the adhesion unit (AD) 30, the substrate G is taken out of the adhesion unit (AD) 30 by the transfer device 21, and is heated and cooled. (HP / COL) It is carried into one of 80a, 80b, and 80c. Then, the substrate G that has been subjected to the cooling process in each heating / cooling processing unit (HP / COL) 80a, 80b, 80c is carried into the reflow processing unit (REFLW) 60, where the reflow process is performed.

  After the reflow process, predetermined heating and cooling processes are performed in the heating / cooling process units (HP / COL) 80a, 80b, and 80c as necessary. The substrate G that has undergone such a series of processing is taken out of the reflow processing unit (REFLW) 60 by the transport device 21, delivered to the transport device 11 of the cassette station 1, and accommodated in an arbitrary cassette C.

  Next, the principle of the reflow method of the present invention performed in the reflow processing unit (REFLW) 60 will be described in comparison with a comparative reflow method in which surface modification processing is not performed. Here, the case where the reflow process is performed in the TFT manufacturing process will be described.

4A to 4C show the process procedure of the comparative reflow method. As shown in FIG. 4A, a gate electrode 202 and a gate line (not shown) are formed on an insulating substrate 201 made of a transparent substrate such as glass, and a gate insulating film 203 such as a silicon nitride film, a-Si. An (amorphous silicon) film 204, an n ⁺ Si film 205 as an ohmic contact layer, a source electrode 206a and a drain electrode 206b, a source electrode resist mask 210 and a drain electrode resist mask 211 are laminated in this order. The source electrode 206a and the drain electrode 206b are etched using the source electrode resist mask 210 and the drain electrode resist mask 211 as a mask, and the surface of the n ⁺ Si film 205 which is a base film is exposed.

Next, a reflow process is performed on the workpiece having such a laminated structure in a solvent atmosphere such as thinner in a reflow processing unit (REFLW) 60 of the reflow processing system 100. By this reflow treatment, the resist constituting the source electrode resist mask 210 and the drain electrode resist mask 211 is softened and has fluidity. In the reflow process, the surface of the n ⁺ Si film 205 in the recess 220 (channel formation region) between the source electrode 206a and the drain electrode 206b is covered with a fluidized resist so that the n ⁺ Si film 205 and the a− The etching is performed for the purpose of preventing the n ⁺ Si film 205 and the a-Si film 204 in the channel formation region from being etched when the Si film 204 is etched. As described above, there is an advantage that the photolithography process can be omitted by reflowing the resist constituting the resist mask for source electrode 210 and the resist mask for drain electrode 211 and reusing the resist mask.

However, when the deformed resist 212 deformed by fluidization exceeds the area of the source electrode 206a and the drain electrode 206b and spreads on the surface of the underlying n ⁺ Si film 205, there arises a problem that the etching accuracy is lowered. That is, as shown in FIG. 4B, the deformed resist 212 protrudes beyond the area of the underlying source electrode 206a and drain electrode 206b, and the n ⁺ Si film 205 and the a-Si film 204 are etched in the next step. In this case, the covering area of the deformed resist 212 which becomes a mask is increased. When the n ⁺ Si film 205 and the a-Si film 204 are etched in this state, as shown in FIG. 4C, the side surfaces of the n ⁺ Si film 205 and the a-Si film 204 after the etching, the source electrode 206a or The side surfaces of the drain electrode 206b are not flush with each other, and a step is generated. As described above, when the TFT is manufactured by performing the subsequent steps in the shape in which the underlying n ⁺ Si film 205 and the a-Si film 204 protrude laterally with respect to the source electrode 206a or the drain electrode 206b, In addition to a decrease in the aperture ratio, which represents the ratio of light passing through, a photocurrent is generated by light striking the a-Si film 204 at this protruding portion, causing an adverse effect such as an increase in electrical noise and a leakage current. There is a concern to bring.

On the other hand, Fig.5 (a)-(d) has shown the process sequence of this invention reflow method. The laminated structure shown in FIG. 5A is the same as that in FIG. 4A relating to the comparative reflow method, and a description thereof will be omitted. As shown in FIG. 5B, the surface modification process is performed on the workpiece having such a stacked structure by the adhesion unit (AD) 30 of the reflow processing system 100. By the surface modification treatment, the exposed surface of the n ⁺ Si film 205 that is not covered with the source electrode 206a and the drain electrode 206b (the source electrode resist mask 210 and the drain electrode resist mask 211) is surface-modified. In this case, it is preferable to perform the surface modification treatment until the contact angle of pure water on the surface modification treatment surface 205a of the n ⁺ Si film 205 reaches 50 degrees or more, for example, 50 to 120 degrees. By performing the surface modification so that the contact angle on the surface modification surface 205a is 50 degrees or more, it is possible to effectively suppress the spread due to the flow of the resist in the subsequent reflow process.

Next, reflow processing is performed in a solvent atmosphere such as thinner in a reflow processing unit (REFLW) 60. By this reflow treatment, the resist constituting the source electrode resist mask 210 and the drain electrode resist mask 211 is softened and has fluidity. The fluidized resist is deformed and attempts to spread over the surface of the underlying n ⁺ Si film 205 beyond the area of the source electrode 206a and the drain electrode 206b, but the surface of the n ⁺ Si film 205 has already been surface-modified, Since the surface modification treatment surface 205a is formed, the flow of the softened resist is suppressed and it is difficult to spread on the surface of the n ⁺ Si film 205.

  Therefore, as shown in FIG. 5C, the phenomenon that the deformed resist 212 after reflowing protrudes beyond the area of the underlying source electrode 206a and drain electrode 206b is a comparative reflow method [see FIG. 4B]. Compared with That is, the area covered with the deformed resist after reflowing is improved to be slightly larger than the areas of the source electrode 206a and the drain electrode 206b.

Therefore, after the ⁿ + Si layer 205 and the a-Si film 204 is etched deformation resist 212 in the next step as a mask, to further remove deformation resist 212, as shown in FIG. 5 ^(d), n + Si The side surfaces of the film 205 and the a-Si film 204 and the side surfaces of the source electrode 206a or the drain electrode 206b can be formed substantially flush with each other. Therefore, there are problems in the comparative reflow method, such as a decrease in aperture ratio due to the a-Si film 204 being formed so as to extend laterally from the source / drain wiring, an increase in electrical noise due to photocurrent generation, and a leakage current. Can be solved.

It has also been confirmed from experimental results that etching accuracy is improved by the surface modification treatment. FIG. 6 is a graph showing test results obtained by examining the effect of surface modification treatment on CD (Critical Dimension). The vertical axis of the graph represents the amount of change (ΔCD) between the CD of the resist pattern and the CD of the pattern after etching, and the horizontal axis represents the time of reflow processing. The surface modification treatment was performed using HMDS at a treatment temperature of 110 ° C. for 120 seconds.
FIG. 6 shows that when the surface modification process using HMDS is performed, the amount of change in CD is small compared to the case where the surface modification process is not performed, and the resist pattern is accurately transferred to the etched shape. This is considered to be a result of suppressing the spread of the resist during reflow by the surface modification treatment.

In the method of the present invention, after the reflow process, a slight ashing process is performed on the deformed resist 212 to further reduce the area covered by the deformed resist 212 and to approach the areas of the source electrode 206a and the drain electrode 206b. become. In this case, the ashing process can be performed, for example, using a parallel plate type plasma processing apparatus, under the conditions of a chamber internal pressure of about 13 Pa and a processing time of about 100 seconds by plasma of a gas containing oxygen such as O _2. This mild ashing process only needs to be able to remove the portions where the deformed resist 212 protrudes from the source electrode 206a and the drain electrode 206b. Therefore, the ashing process is shorter than the ashing that is usually performed for the purpose of removing the thin film portion of the resist by the half exposure technique. For example, a time of about two thirds is sufficient, and the influence on the etching accuracy is hardly a problem.

Further, after the reflow process, when the n ⁺ Si film 205 and the a-Si film 204 are etched using the deformed resist 212 as a mask, the etching of the n ⁺ Si film 205 and the a-Si film 204 proceeds isotropically. By performing etching under such conditions, it is possible to further suppress the phenomenon in which the n ⁺ Si film 205 and the a-Si film 204 protrude laterally from the source electrode 206a and the drain electrode 206b after the etching. For example, in the case of dry etching, a parallel plate type plasma processing apparatus or the like is used, a mixed gas such as SF ₆ or Cl ₂ gas is used as an etching gas type, the pressure in the chamber is 6.7 Pa, and the processing time is 120 seconds. Can be implemented under conditions.

  The reflow speed is determined by the viscous flow of the softened resists 210 a and 211 a and the surface tension of the resists 210 a and 211 a fused in the recess 220. FIG. 7A shows a modeled flow state of the resists 210a and 211a at the time of reflow when the surface modification treatment is not performed. In this model, the speed of viscous flow during reflow and the speed of flow due to surface tension are indicated by the size of the arrows. In addition, the length of the arrow in FIG.7 (b) has the same meaning.

The surface modification treatment is performed on the entire surface of the n ⁺ Si film 205 that is not covered with the source electrode 206a and the drain electrode 206b. Therefore, when the surface modification treatment is performed, as shown in FIG. 7B, the surface of the n ⁺ Si film 205 in the recess 220 exposed between the source electrode 206a and the drain electrode 206b is also surface-modified. As a result, the surface modification treated surface 205a is formed.
However, the inflow speed of the resists 210a and 211a into the recess 220 is not limited to the viscous flow of the resists 210a and 211a softened by the reflow process as described above, but the resist 210a that has flowed into the recess 220 from opposite directions. , 211a is also influenced by the flow promoting action due to the surface tension.
Therefore, even when the surface modification process is performed, after the resists 210a and 211a heading into the recess 220 come into contact, the inflow of the resists 210a and 211a proceeds smoothly due to the surface tension. Then, as shown in FIG. 7B, the flow toward the surface modification surface 205a outside the recess 220 (outside the source electrode 206a and the drain electrode 206b) is suppressed, while the resist 210a entering the recess 220 is suppressed. , 211a proceeds rapidly due to surface tension. With such a mechanism, even after the surface modification treatment is performed, the flow rates of the resists 210a and 211a inside and outside the recess can be made different.

  As described above, by suppressing the resist flow by the surface modification treatment, it is possible to prevent the resist from spreading further while reliably covering the channel region. Accordingly, sufficient etching accuracy can be ensured, and generation of photocurrent in the LCD product can be prevented.

Next, an embodiment in which the reflow method of the present invention is applied to a manufacturing process of a TFT element for a liquid crystal display device will be described with reference to FIGS.
FIG. 8 is a flowchart showing the main steps of a method for manufacturing a TFT element for a liquid crystal display device according to an embodiment of the present invention.
First, as shown in FIG. 9A, a gate electrode 202 and a gate line (not shown) are formed on an insulating substrate 201 made of a transparent substrate such as glass, and a gate insulating film 203 such as a silicon nitride film, a-Si. An (amorphous silicon) film 204, an n ⁺ Si film 205 as an ohmic contact layer, and an electrode metal film 206 such as an Al alloy or Mo alloy are stacked in this order and deposited (step S1).

  Next, as shown in FIG. 9B, a resist 207 is formed on the electrode metal film 206 (step S2). Then, as shown in FIG. 9C, exposure processing is performed on the resist 207 using the exposure mask 300 (step S3). The exposure mask 300 is configured so that the resist 207 can be exposed with a predetermined pattern. By exposing the resist 207 in this manner, an exposed resist portion 208 and an unexposed resist portion 209 are formed as shown in FIG.

  After the exposure, development processing is performed to remove the exposed resist portion 208 and leave the unexposed resist portion 209 on the electrode metal film 206 as shown in FIG. (Step S4). The unexposed resist portion 209 is separated and patterned into a source electrode resist mask 210 and a drain electrode resist mask 211.

Then, using the source electrode resist mask 210 and the drain electrode resist mask 211 as an etching mask, the electrode metal film 206 is etched, and as shown in FIG. Form (step S5). By this etching, the source electrode 206a and the drain electrode 206b are formed, and the surface of the n ⁺ Si film 205 can be exposed in the recess 220 between them.

Next, in the adhesion unit (AD) 30 of FIG. 2, a surface modification process is performed on the exposed surface of the n ⁺ Si film 205 (step S6). The surface of the n ⁺ Si film 205 is surface-modified by a surface modification treatment using a silylating agent or the like, and a surface modification treatment with a contact angle of 50 degrees or more with pure water as shown in FIG. A surface 205a is formed. That is, a state in which the resist hardly flows is formed on the surface modification surface 205a of the n ⁺ Si film 205.

Next, in the reflow process in step S7, a resist softened with an organic solvent such as thinner is allowed to flow into a target recess 220 to be a channel region later. This reflow processing is performed by the reflow processing unit (REFLW) 60 of FIG. In this reflow process, the flow of the softened resist is suppressed on the surface modification treatment surface 205a of the n ⁺ Si film 205, but inflow of the softened resist is accelerated by the action of the surface tension in the recess 220 that later becomes the channel region. The inside of the recess 220 can be reliably covered.

FIG. 10D shows a state in which the concave portion 220 is covered with the deformation resist 212. When the surface modification treatment in step S6 is not performed, the deformation resist 212 extends to, for example, the periphery of the source electrode 206a and the drain electrode 206b (on the side opposite to the recess 220), for example, the n ⁺ Si film 205 as an ohmic contact layer. Since the upper portion is covered, the covered portion is not etched in the next silicon etching step, and there is a problem that the etching accuracy is lowered, leading to a defect of the TFT element and a decrease in yield. In addition, if the area covered with the deformed resist 212 is estimated in advance and designed, the area (dot area) required for manufacturing one TFT element increases, which leads to high integration and miniaturization of TFT elements. There was a problem that it was difficult to respond.

On the other hand, in the present embodiment, the flow of the softening resist to the surface of the n ⁺ Si film 205 other than the recess 220 serving as the channel region is suppressed by the surface modification treatment, and as shown in FIG. The area covered with the deformed resist 212 is substantially limited to the recess 220, which is the target area for the reflow process. Therefore, high etching accuracy can be secured, and it is possible to cope with high integration and miniaturization of TFT elements.

  Next, in step S8, a light ashing process is performed on the deformed resist after the reflow. By this ashing process, the area covered with the deformed resist 212 can be further reduced as shown in FIG. Therefore, the accuracy of the etching performed in the next step S9 can be significantly improved. Note that this ashing process is an optional process, and this ashing process can be omitted when the protrusion of the deformed resist 212 after reflowing to the outside (around the source electrode 206a and the drain electrode 206b) is slight. .

Next, as shown in FIG. 11B, the n ⁺ Si film 205 and the a-Si film 204 are etched using the source electrode 206a, the drain electrode 206b, and the deformed resist 212 as an etching mask (step S9). . Thereafter, the deformed resist 212 is removed by a technique such as a wet process using a resist stripping solution (step S10), and the source electrode 206a and the drain electrode 206b are exposed as shown in FIG. 11C.

Next, the n ⁺ Si film 205 exposed in the recess 220 is etched using the source electrode 206a and the drain electrode 206b as an etching mask (step S11). As a result, a channel region 221 is formed as shown in FIG.

  Although the subsequent steps are not shown, for example, after forming an organic film so as to cover the channel region 221, the source electrode 206a, and the drain electrode 206b (step S12), the source electrode 206a (drain electrode 206b) is formed by photolithography. Are formed by etching (step S13), and then a transparent electrode is formed by indium tin oxide (ITO) or the like (step S14), whereby a TFT element for a liquid crystal display device is manufactured. .

In the above embodiment, by performing the reflow process in step S7, the process of etching the electrode metal film 206 in step S5 and the process of etching the n ⁺ Si film 205 and the a-Si film 204 in step S9 are combined. Since the resist formed by one photolithography, that is, the source electrode resist mask 210, the drain electrode resist mask 211, and the deformed resist 212 can be used, the number of photolithography steps can be reduced and the resist can be saved. . Furthermore, the surface modification process in step S6 ensures high etching accuracy and can cope with high integration and miniaturization of TFT elements.

As mentioned above, although embodiment of this invention has been described, this invention is not limited to such a form.
For example, in the above description, the manufacture of TFT elements using a glass substrate for LCD was taken as an example, but the reflow processing of a resist formed on a substrate such as another flat panel display (FPD) substrate or a semiconductor substrate is performed. The present invention can also be applied to the case where it is performed.

  The reflow method of the present invention can also be applied to a TFT manufacturing process that performs half exposure technology and redevelopment processing.

  The present invention can be suitably used in the manufacture of semiconductor devices such as TFT elements.

It is drawing explaining the outline | summary of a reflow processing system. It is sectional drawing which shows schematic structure of an adhesion unit (AD). It is sectional drawing which shows schematic structure of a reflow processing unit (REFLW). It is drawing used for description of the process procedure of the comparative reflow method. It is drawing which uses for description of the process sequence of this invention reflow method. It is a graph which shows the relationship between CD variation | change_quantity and reflow time. It is a figure explaining the principle of the resist flow to the channel area | region in a reflow process. The flowchart which shows an example of the manufacturing process of a TFT element. The longitudinal cross-sectional view of the board | substrate which shows the state from the laminated film formation on an insulating substrate to after an exposure process in the manufacturing process of a TFT element. The longitudinal cross-sectional view of the board | substrate which shows the state after a reflow process after a development process in the manufacturing process of a TFT element. The longitudinal cross-sectional view of the board | substrate which shows the state after ashing after channel formation in the manufacturing process of a TFT element.

Explanation of symbols

1: Cassette station 2: Processing station 3: Control unit 20: Central transfer path 21: Transfer device 30: Adhesion unit (AD)
60: Reflow processing unit (REFLW)
80a, 80b, 80c: Heating / cooling processing unit (HP / COL)
DESCRIPTION OF SYMBOLS 100: Reflow processing system 201: Insulating substrate 202: Gate electrode 203: Gate insulating film 204: a-Si film 205: n ⁺ Si film 205a: Surface modification processing surface 206a: Source electrode 206b: Drain electrode 210: For source electrode Resist mask 211: Drain electrode resist mask G: Substrate

Claims (15)

  An object to be processed having a lower layer film, and a resist film patterned so as to form an exposed region where the lower layer film is exposed above the lower layer film and a covered region covered with the lower layer film On the other hand, the exposed region of the lower layer film is surface-modified so that resist flow is suppressed, and then the resist of the resist film is softened and flowed to partially cover the exposed region. Reflow method.   The reflow method according to claim 1, wherein the surface modification treatment is performed in a chemical atmosphere containing a silylating agent.   The reflow method according to claim 1, wherein the surface modification treatment is performed so that a contact angle with pure water of the exposed region subjected to the surface modification treatment is 50 degrees or more. A resist film forming step of forming a resist film in an upper layer above the etching target film of the object;
An exposure process for exposing the resist film;
A patterning step of developing the exposed resist film to form a resist pattern;
A reflow step of softening and deforming the resist of the resist film and covering a target region of the film to be etched;
A first etching step of etching an exposed region of the etching target film using the deformed resist as a mask;
Removing the resist after deformation;
A second etching step of etching the target region of the film to be etched that is reexposed by removing the resist after the deformation;
Including
Prior to the reflow step, the pattern forming method includes a step of performing a surface modification process on the exposed region in advance so as to suppress the flow of the softened resist.   The pattern forming method according to claim 4, further comprising, after the reflow step, a step of ashing the deformed resist to reduce a covering area thereof.   6. The pattern forming method according to claim 4, wherein the surface modification treatment is performed in a chemical atmosphere containing a silylating agent.   7. The surface modification treatment according to claim 4, wherein the surface modification treatment is performed so that a contact angle with pure water of the exposed region subjected to the surface modification treatment is 50 degrees or more. Pattern formation method. In the object to be processed, a gate line and a gate electrode are formed on a substrate, and a gate insulating film covering them is formed. Further, an a-Si film and an ohmic contact Si film are sequentially formed on the gate insulating film from the bottom. And a laminated structure in which a source / drain metal film is formed,
The pattern forming method according to claim 4, wherein the etching target film includes at least the ohmic contact Si film. Forming a gate electrode on the substrate;
Forming a gate insulating film covering the gate electrode;
Depositing an a-Si film, an ohmic contact Si film, and a source / drain metal film in order from the bottom on the gate insulating film;
Forming a resist film on the source / drain metal film;
Exposing the resist film using a predetermined exposure mask; and
A mask patterning step of developing and patterning the exposed resist film to form a resist mask for a source electrode and a resist mask for a drain electrode;
A metal film etching step of etching the source / drain metal film using the source electrode resist mask and the drain electrode resist mask as a mask to form a source electrode and a drain electrode;
A surface modification step of performing a surface modification process on the exposed region of the ohmic contact Si film not covered with the source electrode and the drain electrode so that the flow of the resist is suppressed;
An organic solvent is allowed to act on the resist mask for the source electrode and the resist mask for the drain electrode to soften and deform the resist, thereby at least the ohmic in the recess for the channel region between the source electrode and the drain electrode. A reflow process of covering the contact Si film with a deformed resist;
Etching the lower ohmic contact Si film and the a-Si film using the resist after deformation and the source and drain electrodes as a mask;
Removing the deformed resist and exposing the ohmic contact Si film again in the recess for the channel region between the source electrode and the drain electrode;
Etching the ohmic contact Si film exposed in the recess for the channel region between the source electrode and the drain electrode as a mask;
A method for manufacturing a TFT, comprising:   The method of manufacturing a TFT according to claim 9, further comprising an ashing step of ashing the deformed resist to reduce a covering area thereof after the reflow step.   11. The TFT according to claim 9, wherein in the step of etching the ohmic contact Si film and the a-Si film, dry etching is performed under a condition in which etching proceeds isotropically. Production method.   The method for manufacturing a TFT according to claim 9, wherein the surface modification treatment is performed in a chemical atmosphere containing a silylating agent.   13. The surface modification treatment according to claim 9, wherein the surface modification treatment is performed so that a contact angle with pure water of the exposed region subjected to the surface modification treatment is 50 degrees or more. TFT manufacturing method. A computer-readable storage medium storing a control program that runs on a computer,
A computer-readable storage medium for controlling the reflow processing system so that the reflow method according to any one of claims 1 to 3 is performed when the control program is executed. A surface modification processing unit for performing a surface modification treatment on the workpiece;
A reflow processing unit for softening and fluidizing the resist on the target object after the surface modification treatment in a solvent atmosphere;
A control unit that controls the reflow method according to any one of claims 1 to 3 to be performed in the processing chamber;
A reflow processing system.

Images