TWI762526B - Mask holder with controlled adjustment - Google Patents

Abstract

The invention relates to a support for a mask (1) which, when carrying out the coating method, is positioned on the surface to be coated of a substrate (2) in order to limit the deposition of layers to the surface covered by the mask (1) The shape and position of the pre-determined surface sections, wherein the sections (4, 4', 4", 4", 16) of the frame (3) of the support are in such a way that the cover (1) can be deformed The variable tension acts on the edge (1') of the mask (1). The present invention proposes the following innovations: a sensor (5) for measuring the actual position of the mask (1) relative to the substrate (2); elements (6, 7, 8) for changing the position of at least one first section (4) of the frame (3) relative to the at least one second section (4') of the frame (3); and having a controller The control loop of (9) is to change the actual position of the mask (1) in the direction of the prescribed position of the mask (1) by changing the tension (Z, Z', Z", Z''').

Furthermore, the present invention relates to a method of adjusting the position of the mask, wherein a control loop is used.

Description

Mask Stand with Controlled Adjustment

The present invention relates to a support for a mask which, when carrying out a coating method, is placed on the surface to be coated of a substrate in order to limit the deposition of layers to that surface which is predetermined by the shape and position of the mask on a defined surface section, wherein the section of the frame of the bracket acts on the edge of the mask with a variable tension force capable of deforming the mask.

Furthermore, the present invention relates to a method of adjusting the position of a mask which, when carrying out the coating method, is on the surface to be coated of a substrate in order to limit the deposition of layers to the surface by the shape of the mask and the on a surface section predetermined by a position, wherein a tensile force capable of deforming the mask is applied to the edge of the mask by the segment of the frame of the support.

The device according to the invention and the method according to the invention find application in the deposition of a laterally structured layer on a substrate, in which the layer-forming material is introduced into a reactor in gaseous form, in particular in the form of organic molecules in the vapour state (eg CVD or PVD reactor) process chamber. The gaseous starting materials condense or react on the surface of the substrate, and layers are formed in the process. In particular, the present invention relates to an apparatus applicable to the manufacturing process of LCD displays or OLED displays. It uses a mask with windows separated by strips which keep separate surface sections of the substrate surface free. On these surface segments are deposited different starting materials that will emit light in different colors when electrically actuated. The mask is made of a thin-walled metal sheet that is laterally structured and stretched along the extending direction of the mask when a directional pulling force is applied to the edge of the mask, so that the window is located at a predetermined position. US 2014/0158044 A1 describes a mask frame on which the edges of a rectangular mask are fixed, and the mask frame has tension elements for applying directional tension to the mask at different positions, respectively.

WO 2007/133252 A2 discloses that the temperature of the mask is adjusted when the mask is attached to the mask frame. Therein, another temperature is used as a framework for temperature adjustment, so that when the temperature changes, transverse stresses are formed in the mask surface due to the different thermal expansion coefficients.

US 7,765,669 B2 discloses a method of manufacturing a mask, wherein the mask is stretched during the manufacturing process.

US 2016/0376703 A1 describes a method and apparatus for adjusting a mask relative to a substrate surface, wherein adjustment marks of the mask or substrate are detected by a CCD sensor, and an actuating element in the form of a threaded spindle changes the position of the holder The position of the opposing section.

US 2015/0068456 A1 discloses a bracket for a mask. The bracket has four frame sides whose position relative to the base plate can be changed by means of threaded spindles or piezoelectric elements.

In order to stretch the mask by adjusting the temperature of the frame holding the edge of the mask, the material of the mask and the material of the frame may have different thermal expansion coefficients, so the temperature change will cause the mask to deform. Through the targeted deformation, the mask can be brought from the actual position into the predetermined position, because the opposing edge sections of the mask are separated from each other by the application of the tensile force. Other actuating elements can also be provided in order to apply a directional pulling force to the edges of the mask. The temperature adjustment of the substrate or the mask can lead to mechanical deformation of the frame or the mask, and since the frame and the substrate are affected differently, especially individually, the mechanical deformation cannot be determined computationally.

The purpose of the present invention is to improve the conventional mask holder in the prior art to facilitate its use, and to provide a method for improving the position adjustment of the mask relative to the prior art.

This object is achieved through the invention given in the scope of the application. The subsidiary item is not only a beneficial improvement of the invention given in the concurrent claim, but also an independent solution for the purpose of improving the same type of stent to facilitate its use.

First and foremost: use a control loop to adjust the mask position. The control loop of the present invention has sensors for determining the actual position of the mask relative to the substrate. The control loop further has an actuating element for changing the position of the at least one first section of the frame relative to the at least one second section of the frame. In addition, the control loop further has a control device for generating manipulated variables, and the manipulated variables are used to actuate the actuating elements, so that the actual position of the mask changes in the direction of the specified position due to the change of the pulling force acting on the edge of the mask. The control loop may be a PID control loop. The actuating element preferably changes the distance between two opposing sections by changing the temperature of one or several sections of the frame. The frame may be a rectangular frame holding a rectangular mask. The frame forms opposed frame sides. By changing the temperature of one of the sides of the frame, changing its length, and then changing the spacing of the opposite sections of the frame. The sensor is preferably an optical sensor. The sensor may be an imaging sensor with imaging optics by which an image of the frame surface is produced on a sensor (eg, a CCD sensor). The actual position of the mask, in particular the actual position of the edge regions of the mask, can be determined by means of the image evaluation. The actuating element is preferably a heating element and/or a cooling element. Each frame side can have cooling channels and/or heating channels. Only cooling channels or only heating channels can be provided. The present invention also proposes that the cooling channel and the heating channel are simultaneously arranged side by side in the extending direction of the frame side. Each frame side can be tempered separately from any other frame side. Instead of heating elements and/or cooling elements, mechanical means can also be provided to vary the distance between the two frame sections. The sections separated from each other by the actuating elements are the edge regions of the frame and the hood, in which edge regions the hood and the frame are connected to each other by means of tension transmission elements. The tensile force transmission element may be a form-fitting member, such as a pin, screw or similar. The edges of the mask may also be connected to sections of the frame by means of a press fit or material engagement. In the improved solution of the present invention, the sensor cooperates with the adjustment mark. A first adjustment mark can be set, which corresponds in particular to the corner area of the mask. The first adjustment mark can be a window-shaped opening opened on the mask. A second adjustment mark corresponding to the substrate may be provided. The second adjustment mark may correspond directly to the substrate or indirectly to the substrate. The adjustment marks that correspond directly to the substrate can be, for example, colored areas on the surface of the substrate to be coated. The adjustment marks that indirectly correspond to the substrates may also be formed by substrate holders that hold the substrates. These adjustment marks can also be optically distinguishable marks. It can be recognized by the optical sensor through the transparent substrate. The direction and magnitude of the pulling force applied to the edge of the mask are changed by the actuating element, so that the adjustment marks are aligned with each other. This is achieved by means of the control device of the control loop, which obtains the actual value of the position of the adjustment marks, preferably located in the corner areas, and issues adjustment commands to the actuating element. The hood may be constructed of stainless steel and the frame may be constructed of high-quality steel. The expansion coefficient of high-quality steel is greater than that of the substrate made of glass. By adjusting the temperature of the mask frame in the range between 20°C and 60°C, the mask made of In steel can be mechanically stretched so that the adjustment marks are aligned with each other. The present invention implements the adjustment through a closed control path, so there is no need to calculate the influencing factors. The measuring device formed by the sensor can be formed by up to four CCD cameras provided at the corners of the substrate and the frame. At the corners, the precise position of the substrate and the mask is determined, in particular by means of the above-mentioned adjustment marks. At these locations, different linear thermal or mechanical linear expansions can be measured by means of sensors, especially cameras. Based on these values, the control device determines the temperature specification of the mask frame. Bring the mask frame to this specified value. Next, the position change is measured by the sensor, and the approximation of the predetermined value and the actual value is improved in another control step. Therein, different sections of the frame may have different temperatures. The control of mask stretch and mask position preferably includes two steps here. In the first step, the center of the mask and the center of the substrate are aligned with each other. Other origins of the coordinate system of the mask and the coordinate system of the substrate can also be aligned with each other. If the adjustment marks on the corners of the mask and the substrate deviate from each other after the origin alignment, the mask is deformed within its elastic range in the second step until the adjustment marks of the substrate and the mask are aligned with each other. The force for stretching the mask can be generated mechanically or by tempering the mask or mask frame. According to the present invention, the above-mentioned two-stage adjustment for the mask position only needs to be performed once, and when the substrate is replaced, it is only necessary to reach the previously measured temperature of each mask frame section. Adjustment of the spacing between frame sections through temperature changes can be achieved by active heating or active cooling. In deposition processes in which the substrate is cooled in order to deposit layers by condensation, temperature regulation can also be achieved by reducing the cooling power.

1‧‧‧Mask

1'‧‧‧Edge

2‧‧‧Substrate

3‧‧‧Framework

4, 4', 4", 4'''‧‧‧Frame side, section

5‧‧‧CCD camera

6‧‧‧Heating device

7‧‧‧Cooling device

8‧‧‧piezoelectric element

9‧‧‧Control device

10‧‧‧Substrate holder

11‧‧‧Adjustment mark

12‧‧‧Adjustment mark

13‧‧‧Window

14‧‧‧Stripes

15‧‧‧Intake mechanism

16‧‧‧Corner

17‧‧‧Tension transmission element

Z, Z, Z", Z'''‧‧‧pull

Embodiments of the present invention will be described below. In the accompanying drawings: Fig. 1 is a schematic diagram of the control circuit of the present invention; Fig. 2 is a schematic diagram of several components of the coating device; Fig. 3 is an enlarged view of part III in Fig. 2; Fig. 4 is a top view of the mask frame 3 5a to 5d are parts Va to Vd before the position adjustment of the mask 1 on the mask frame 3 is implemented; 7 is a top view of the mask frame 3 provided by another embodiment.

FIG. 1 shows a schematic diagram of the structure of the control device of the present invention. The rectangular substrate 2 is placed on the rectangular substrate holder 10 . On the free surface of the substrate 2 is a mask 1, which has a large number of windows separated by strips. The mask edge 1 ′ of the mask 1 protrudes from the side edges of the substrate 2 and the substrate frame 10 .

The substrate holder 10 is surrounded by a rectangular frame 3 with four frame sides 4, 4', 4", 4"'. The edge 1' of the mask 1 is fixed to the frame side 4 of the frame 3 in such a way that This enables a tensile force directed in the transverse extension direction of the cover 1 to be transmitted from the frame sides 4 , 4 ′ to the cover 1 .

In each of the four frame sides 4, 4', 4", 4"' there are cooling channels 7 and heating channels 6. The cooling channels 7 are for the passage of cooling liquid and the heating channels 6 are for The heating liquid passes through. By adjusting the flow rate of the refrigerant and heating medium passing through the channels 6, 7, the temperature of each frame side 4, 4', 4", 4"' can be individually adjusted. The shield 1 is made of steel and its thermal expansion coefficient is smaller than that of the frame 3 and its frame sides 4 and 4 ′. Therefore, changes in the temperature of the frame sides will cause changes in the mechanical stress on the shield 1 .

The flow of refrigerant and heating medium passing through the passages 6 and 7 is controlled by the control device 9 . For this purpose, an on-off valve or a regulating valve can be provided, for example, by means of which the refrigerant flow rate of the refrigerant tempered to a specific temperature or the heat medium flow rate of the heat medium tempered to a specific temperature can be fed into the channel in a controlled manner 6.7.

There are optical sensors, in particular in the form of CCD cameras 5 , by means of which the actual values of the position of the mask, in particular in the regions of the four corners of the frame 3 , are determined. There are adjustment marks 11 and 12 not shown in FIG. 1 , which are aligned with each other so as to achieve the predetermined position of the mask 1 . The first adjustment marks 11 are formed by a mask, and the second adjustment marks 12 are formed by a substrate. The CCD camera 5 provides the control device 9 with actual values.

In the aforementioned temperature regulating devices 7, 6, the temperature-regulated liquid passes through the cooling channel 7 or the heating channel 6, and alternatively, other temperature regulating components, such as resistance heaters or Peltier cooling elements, may also be provided.

FIG. 2 shows a cross-section of the coating system in which the gaseous starting material flows from the exhaust port of the showerhead air intake mechanism 15 into the process chamber. The air intake mechanism 15 is tempered to an elevated temperature at which the organic vapors contained in the process gas do not condense.

The substrate rack 10 has cooling elements that are not shown in the figure, and the substrate rack 10 , which can be located below or above the air intake mechanism 15 , is adjusted to a temperature by these cooling elements, at which temperature, the organic vapors are trapped in the substrate 2 . Condensed on the surface of the substrate, the substrate is located on the wide side of the substrate rack 10 directed toward the process chamber.

The substrate 2 is covered by a mask 1 having a window 13 and a strip 14 defining the window 13 . The mask is a shadow mask attached to the broad surface of the substrate 2 to be coated in a surface-contact manner.

FIG. 3 shows one of the four edge regions of the rectangular frame 3 holding the mask 1 . The edge 1 ′ of the cover 1 is connected to the frame side 4 of the frame 3 by means of a tension transmission element 17 . The tensile force transmission element can be a form-fit element or also a weld seam.

The mask 1 has a first adjustment mark 11 in the corner area which is constructed as a window. The substrate 2 has a second adjustment mark 12, which can be optically distinguished from its surroundings, so that the positions of the two adjustment marks 11, 12 can be determined by the optical sensor 5, preferably a CCD camera.

Figure 4 shows a schematic top view of the mask 1 and the frame 3 holding the mask 1 at the edge 1' and its four frame sides 4, 4', 4", 4"' arranged at right angles to each other. Figure 4 5a to 5d respectively show, in enlarged views, the corner regions of the mask 1 placed in the first step in a center-aligned manner on the substrate 2. Adjustment marks 11, 11', 11", 11' of the mask 1 The position of '' is deviated from the position of the adjustment marks 12, 12', 12", 12"' of the substrate 2.

In particular, the sections of the frame 3, in particular the frame sides 4, 4', 4", 4''' are tempered at different temperatures There is a relative displacement away from each other, whereby pulling forces Z, Z', Z", Z''' of individual directions and individual strengths can be applied to the corners of the mask 1, so that the adjustment marks 11, 11', 11", 11''' is aligned with its corresponding adjustment marks 12, 12', 12", 12''', as shown in Figs. 6a to 6d.

However, it is also possible to apply tension Z, Z', Z", Z" respectively to one of the relevant edges of the mask 1 by tempering the frame sides 4, 4', 4", 4"" ' so that the entire edge of the mask is pulled evenly in one direction. In this case, adjustment marks for implementing control can also be provided on the edges of the mask 1 and the substrate 2 . The adjustment marks are aligned with each other by the control device.

The above-mentioned "mutual alignment" of the adjustment marks 11, 11', 11", 11''', 12, 12', 12", 12''' is achieved through iterative successive control steps in the control loop. These control The step is to measure the actual values of the adjustment marks 11, 11', 11", 11"' with respect to the adjustment marks 12, 12', 12", 12"' by the CCD camera 5, respectively, and then, through the actuating element pair For example, the flow rate of refrigerant or heat medium in cooling channel 7 or heating channel 6 is adjusted so that the actual value is close to the specified value. These successive adjustment steps are repeated until the adjustment marks 11, 11', 11", 11"', 12, 12', 12", 12"' are sufficiently aligned. The temperature of the side of the frame or the flow of cooling medium or the flow of heating medium entering the side of the frame when the cover 1 is precisely fitted on the base plate 2 is stored. This way, mask adjustments only need to be performed once. When the mask is continued to be used in the production process of coating several substrates in sequence, only the measured temperature of the frame sides 4, 4', 4", 4"' needs to be reached.

In the embodiment shown in Figure 7, the corner regions 16 provided with the adjustment marks 11, 12 are displaced relative to the frame sides 4 extending between the corner regions 16 by the array 8 of piezoelectric elements. The corner regions are formed by corner pieces, which may have tensile force transmission elements.

The foregoing embodiments are intended to illustrate the inventions contained in the present application as a whole, and these inventions independently constitute improvements over the prior art through at least the following feature combinations: a bracket for a mask 1, characterized in that: a sensor 5, used to measure the actual position of the mask 1 relative to the base plate 2; actuating elements 6, 7, 8, used to change at least one first section 4 of the frame 3 relative to at least one second of the frame 3; The position of the section 4'; and a control loop with a control device 9 to make the actual position of the mask 1 towards the prescribed position of the mask 1 by changing the tension Z, Z', Z", Z"" direction changes.

A bracket is characterized in that: the actuating elements 6, 7 change the distance between the two opposite frame sides 4, 4', 4", 4"' of the rectangular frame 3 by changing the temperature.

A bracket is characterized in that: the sensors 5 are optical sensors.

A stand, characterized in that the sensors 5 have an optical imaging system and in particular a CCD camera.

A bracket characterized in that the actuating elements have heating elements and/or cooling elements 6 , 7 .

A support is characterized in that: the heating elements and/or cooling elements 6, 7 are separate passages for cooling liquid and/or heating liquid to pass through.

A bracket, characterized in that the actuating elements are piezoelectric elements 8 arranged in particular between the segments 4 , 4 ′, 4 ″, 4 ″, 16 of the frame 3 .

A bracket is characterized in that: the mask 1 has first adjustment marks 11, and the first adjustment marks can be aligned with the second adjustment marks 12 of the base plate 2.

A bracket is characterized in that the adjustment marks 11 and 12 are arranged on the corners of the cover 1 and the base plate 2 .

A method for adjusting the position of a mask 1, which is characterized in that: the actual position of the mask 1 relative to the substrate 2 is measured by a sensor 5, and a control loop is based on the actual position of the mask 1 and the mask 1. The deviation between the specified positions generates manipulated variables for controlling the actuating elements 6, 7, 8, by means of which the actuating elements change at least one first section 4 of the frame 3 relative to at least one first section 4 of the frame 3. The positions of the two sections 4 ′ are such that the actual position of the mask 1 is close to the prescribed position of the mask 1 .

A method of adjusting the position of a mask 1, characterized in that the manipulated variable is the temperature of the sections 4, 4', 4", 4"' of the frame 3, wherein the different sections 4, 4 are separately ', 4", 4''' to adjust the temperature.

A method for adjusting the position of the mask 1 is characterized by: aligning the first adjustment marks 11 and the second adjustment marks 12 especially provided at the corners of the rectangular frame 3 and the rectangular base plate 2 with each other.

All disclosed features (either as a single feature or as a combination of features) are essential to the invention. Therefore, the disclosure content of this application also includes all the content disclosed in the related/attached priority files (copy of the earlier application), and the features described in these files are also included in the patent scope of this application. The subordinate items describe the features of the improvement scheme of the present invention with respect to the prior art with its features, and its purpose is mainly to file a divisional application on the basis of these claims.

1‧‧‧Mask

1'‧‧‧Edge

2‧‧‧Substrate

3‧‧‧Framework

4‧‧‧Frame side, section

5‧‧‧CCD camera

10‧‧‧Substrate holder

11‧‧‧Adjustment mark

12‧‧‧Adjustment mark

13‧‧‧Window

14‧‧‧Stripes

17‧‧‧Tension transmission element

Z‧‧‧pull

Claims (13)

A holder for a mask which, when carrying out a coating method, is located on the surface to be coated of a substrate (2) in order to limit the deposition of layers to the surface defined by the shape and position of the mask (1) On a predetermined surface section, wherein the opposing section of the support acts on the edge (1') of the mask (1) with a variable tensile force capable of deforming the mask (1), with: sensing device (5) for determining the actual position of the mask (1) relative to the base plate (2); actuating elements (6, 7, 8) for changing at least a first section of the frame (3) (4) the position relative to the at least one second section (4') of the frame (3); and a control loop with a control device (9) for changing the tension (Z, Z', Z", Z by changing the ''') to change the actual position of the mask (1) in the direction of the prescribed position of the mask (1), characterized in that the sections are defined by the frame side of the rectangular frame (3) of the bracket Sides (4, 4', 4", 4"') are formed, and the actuating elements (6, 7) change the two opposite frame sides (4, 7) of the rectangular frame (3) by changing the temperature 4', 4", 4''') spacing. The support of claim 1, wherein the sensors (5) are optical sensors. A stand as claimed in claim 1, wherein the sensors (5) have optical imaging systems and in particular CCD cameras. A holder for a mask which, when carrying out a coating method, is located on the surface to be coated of a substrate (2) in order to limit the deposition of layers to the surface defined by the shape and position of the mask (1) On a predetermined surface section, wherein the opposite section of the support acts on the edge (1') of the mask (1) with a variable tensile force capable of deforming the mask (1), characterized in that: The bracket has a frame (3) comprising opposing frame sides (4, 4', 4", 4"'), the length of the frame sides being variable to vary the spacing, wherein the pulling force is by means of the pulling force The transfer element (17) transfers to the edge (1') of the mask (1). The bracket of claim 4, wherein actuating elements (6, 7) are provided to change the distance. The stand of claim 5, wherein the actuating elements have heating elements and/or cooling elements (6, 7). The stand according to claim 6, wherein the heating elements and/or cooling elements (6, 7) are separate passages through which cooling liquid and/or heating liquid can pass. The bracket of claim 5, wherein the actuating elements are piezoelectric elements (8), and the piezoelectric elements are especially arranged on the frame sides (4, 4', 4", 4''') or sections of corner pieces (16). The bracket of claim 1 or 4, wherein the mask (1) has first adjustment marks (11), and the first adjustment marks can be aligned with the second adjustment marks (12) of the base plate (2) . The bracket of claim 9, wherein the adjustment marks (11, 12) are provided at the corners of the cover (1) and the base plate (2). A method of adjusting the position of a mask which, when carrying out a coating method, is located on the surface to be coated of a substrate (2) in order to limit the deposition of layers to the surface by the shape and position of the mask (1) on a predetermined surface section, wherein a tensile force is applied to the edge (1') of the mask (1) by a section of the frame (3) which can deform the mask (1), by sensing The device (5) measures the actual position of the mask (1) relative to the substrate (2), and the control loop is generated according to the deviation between the actual position of the mask (1) and the prescribed position of the mask (1). Manipulating variables to control actuating elements (6, 7, 8) by means of which actuating elements vary at least a first section of the frame (3) relative to at least a second section of the frame (3) position, so that the actual position of the mask (1) is close to the specified position of the mask (1), characterized in that: the manipulated variable is the temperature of the frame (3) and/or the frame (3) is a rectangle box Length of shelf sides (4, 4', 4", 4'''). The method of claim 11, wherein different sections of the frame sides (4, 4', 4", 4"') are tempered separately. The method of claim 11, wherein the first adjustment marks (11) and the second adjustment marks (12) provided at the corners of the rectangular frame (3) and the rectangular substrate (2) are aligned with each other.

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