JP2007115978A - PRESSURE DEVICE AND SEMICONDUCTOR DEVICE MANUFACTURING METHOD - Google Patents

Abstract

When a stacked three-dimensional semiconductor device is formed by stacking wafers on which semiconductor devices are formed, the wafers to be stacked must be aligned and overlapped to uniformly press the entire wafer surface. It is. However, the entire apparatus including the frame structure of the pressurizing device is deformed with pressurization, and uniform pressurization is difficult. As a result, mutual electrode bonding could not be performed uniformly over the entire wafer surface.
A force is applied to a wafer (substrate) by applying a force that attracts each other to a pressure member, and the member to which the pressure is applied takes a closed body structure. And this structure is supported by the support leg standing on the base board. This prevents the entire device from being deformed by the applied pressure.
[Selection] Figure 1

Description

  The present invention relates to a method for manufacturing a stacked semiconductor device, and more particularly to a technique for transporting aligned wafers used in a step of stacking and connecting wafers on which high-definition semiconductor devices are formed.

    In recent years, portable electronic devices such as mobile phones, notebook computers, portable audio devices, and digital cameras have made remarkable progress. Along with this, in addition to improving the performance of the chip itself as well as the performance of the chip itself, improvements in the chip mounting technology are also sought. There is a need for improved packaging technology.

  In order to reduce the chip mounting area, stacking chips is used to increase the amount of mounted chips without increasing the mounting area, thereby reducing the effective mounting area. For example, JP-A-2001-257307, 2002-050735, and JP-A-2000-349228 disclose such techniques. The first one is based on a wire bond system in which a chip and a chip or a chip and a mounting substrate are connected by a wire. The second one is based on a flip chip method in which a chip and a chip or a chip and a mounting substrate are connected via a micro bump provided on the back surface of the chip. In the third method, the chip and the chip or the chip and the mounting substrate are connected by using both the wire bond method and the flip chip method.

  In order to increase the driving speed of a semiconductor device, a method realized by reducing the thickness of the chip and using a through electrode is effective. For example, Japanese Patent Laid-Open No. 2000-208702 shows an example of mounting with a thickness of micron.

  In the wire bond method, a wire is stretched around the semiconductor bare chip. For this reason, a large occupied area larger than the occupied area of the semiconductor bare chip itself is required, and it takes time because the wires are stretched one by one. On the other hand, in the flip-chip method, since the connection is made by the micro bump formed on the back surface of the semiconductor bare chip, the area for connection is not particularly required, and the area necessary for mounting the semiconductor bare chip is the semiconductor bare chip. It can be almost equal to its own area. Further, since the connection surface can have all the bumps necessary for connection, connection to the wiring board can be performed in a lump. Therefore, the flip-chip method is the most suitable method for minimizing the occupation area necessary for mounting the semiconductor bare chip to achieve high-density mounting, reducing the size of the electronic device and shortening the construction period.

  In addition to the improvement of the chip-mounting substrate and the connection method between the chip and the chip, as a means of reducing the manufacturing cost, a rewiring layer or the like is formed before separating the wafer on which the semiconductor chip is formed into individual chips. Connection bumps are formed, and in some cases, sealing with resin is performed. A semiconductor device in which processing at the wafer level is effective is a semiconductor device having a high manufacturing yield and a small number of pins, and has many advantages particularly in the production of memory. (NIKKEI MICRODEVICE February 2000, page 56 and NIKKEI ELECTRONICS 2003.9.1 P.127).

  On the other hand, development of a manufacturing apparatus for manufacturing such a semiconductor device has also been earnestly performed. For example, the literature introduces an apparatus for aligning and bonding wafers to be bonded. (P. Lindner et al .: 2002 Electronic Component and Technology Conference P.1439). In addition, a similar technique is disclosed in Japanese Patent Laid-Open No. 9-148207.

  By the way, as described above, bumps are generally formed for electrode bonding by flip chip, and bonding between bumps and pads and between bumps and bumps is performed. For this joining, a low melting point metal sympathetic bonding method such as solder, a mechanical pressing method using shrinkage during curing of a nonconductive resin, an anisotropic conductive material in which conductive fine particles are dispersed. There are a method of bonding with conductive fine particles with a conductive resin interposed, and a method of metal diffusion bonding in which bump bumps are heated and pressed to diffuse the metal molecules of the bumps.

  However, when performing such electrode bonding, it is necessary to press the bonding surfaces with a large pressure. The structure of the pressurizer that generates a large pressure is based on the mechanism of a normal press.

  As an electronic component bonding apparatus applying a press mechanism, for example, there is a pressure bonding apparatus used in a liquid crystal display element manufacturing process, an anisotropic conductive film bonding process, and an FPC bonding process. The following techniques are used.

As a pressurizing mechanism for bonding the liquid crystal substrates and assembling the liquid crystal substrates, the pressurizing plate is attached to the lifting plate or the lifting frame, and the lifting plate or the lifting frame is moved up and down using the column fixed to the base base as a guide The pressure plate employs a mechanism for pressing the object to be pressed. (See Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4). In addition, when pressurizing with a larger pressure, the entire pressurizing apparatus may be deformed or distorted, and the parallelism between the pressing surfaces, and therefore the parallelism between the objects to be pressed may be distorted. In order to prevent such deformation and distortion, measures for fixing a tie bar for preventing deformation with a screw and welding of an auxiliary plate are performed. (Patent Literature 5, Patent Literature 6). In order to prevent this deformation, a method of using a loop frame as a frame is also disclosed in order to disperse the force applied to the pressure device. (See Patent Document 7). As for the method of applying the pressing force, there is a method in which the peripheral portion of the pressing plate is pressurized using a linear motor or a motor and a ball screw, in addition to the hydraulic pressure or pneumatic pressure along the central axis of the pressing portion. (See Patent Document 8 and Patent Document 9).
JP-A-10-282502 JP 2004-70274 A JP-A-6-123865 JP 2004-37594 A Japanese Patent Laid-Open No. 10-34397 JP 2001-79695 A JP-A-10-58195 Japanese Patent Laid-Open No. 10-20297 JP 2004-268113 A

The pressurizing means described in Patent Documents 1 to 4 are basically means for realizing bonding with a seal or an adhesive while maintaining a uniform interval in the bonding process. Therefore, it has been found that the present invention is not suitable for a bonding process that requires a high pressure such as joining electrodes by pressure or pressure and heat as in the present invention. That is, in the pressure devices disclosed in Patent Documents 1 to 4, basically, a bonded substrate is placed on a table, and conveyance and alignment between the substrates are performed. For this purpose, a table driving unit for alignment is equipped. However, if the heating temperature is 350 ° C. and the pressure is several tens Kgf / cm ² in order to join the electrodes by metal bonding, the rigidity of the table driving unit is low. The pressure device is deformed and the parallelism of the bonding surfaces is lost, so that a predetermined pressure and its distribution cannot be obtained. The pressurization mechanism described in Patent Documents 5 and 6 aims to achieve pressure and pressure distribution as designed by attaching an auxiliary reinforcing member to prevent deformation of the frame of the pressurization device accompanying pressurization. Technology. This method reduces the instability of the mutual positional relationship between the pressure plates due to deformation, but if the pressure part is heated to a temperature required for metal bonding of the joint part, the members involved in the pressure cannot be predicted due to thermal expansion. Cause significant deformation. It is conceivable to measure this deformation and control the applied pressure according to the deformation. However, the base base itself on which the measuring device for measuring the deformation is deformed, the installation position of the measuring device fluctuates, and the amount of deformation is accurate. Can no longer be measured. Furthermore, when the loop frame described in Patent Document 7 for reducing the deformation of the frame is used, the deformation amount is reduced, but the mutual position holding accuracy required for the electrode bonding formed on the semiconductor wafer is satisfied. I couldn't.

  The object of the present invention is to provide a pressurizing apparatus that can be used for high-precision processing with such heating and pressurization.

In order to achieve the above object, the present invention uses the following means.
A pressurizing device for pressurizing a laminated substrate,
A pressure member attached to the first frame;
A holding member that is attached to the second frame and holds the substrate;
A driving device for pulling the first frame and the second frame;
Have
The first frame or the second frame has a flange portion;
The flange portion is a pressurizing device that is supported by a support leg that stands on a base base.

  In this device configuration, a force is applied so as to pull the first frame and the second frame, and pressure is applied to the pressure member and the holding member attached to the two frames. A flange portion is provided on one of the two frames that are integrated when pressurized, and a support leg fixed to the base board supports the flange portion. In this mechanism, pressure is applied to the bonded substrate by the force that attracts the two frames, so the reaction force due to the applied pressure slightly deforms the two frames, but does not affect the rest of the device. Thus, deformation of the entire apparatus including the base board is prevented.

In the above means, a static fluid pressure can be used as a pressure source. By using the static fluid pressure as a pressure source, high pressure can be easily controlled with high accuracy. Also,
Two frames may be pulled together with screws.

  Further, in the above means, an interferometer for measuring the positional relationship between the pressure member and the holding member coupled to the upper and lower frames may be disposed on the base substrate. Since the interferometer is disposed on the base substrate, and the base substrate is not deformed with pressure, the interferometer is not displaced. Therefore, it becomes possible to monitor the positional relationship between the pressure member and the holding member stably as necessary. This makes it possible to detect changes in the pressure distribution and the like accompanying the deformation of the upper and lower frames, and to control the pressure distribution with high accuracy.

  Furthermore, the pressurizing apparatus has a heater for heating the substrate. When joining the electrodes, it becomes possible to activate the metal molecules constituting the electrodes by heating, or to simultaneously heat the adhesive resin.

  Furthermore, the pressurizing apparatus is provided with a chamber for making the atmosphere to be pressurized an inert gas atmosphere or a vacuum. If the electrode surface is dirty or oxidized when the electrodes are joined, the joining is incomplete. By setting the atmosphere to an inert gas atmosphere or a vacuum state, contamination and oxidation of the electrode surface are prevented, and incomplete bonding is eliminated.

  A further means for solving the above problem is to use the pressure device in the electrode bonding step in the manufacturing process of the stacked semiconductor device. When the electrodes are bonded at the wafer level by heating and pressing using the pressurizing apparatus of the present invention, the pressure uniformity is high, so that uniform electrode bonding can be obtained over the entire wafer surface.

  In the present invention, when the bonded substrate is pressed, the reaction force due to the pressing does not act on the components of the pressing device other than the members directly related to the pressing. For this reason, it is not necessary to take measures against deformation of the entire apparatus, and it is possible to reduce the weight of the entire apparatus and to stabilize the entire apparatus while making the entire apparatus compact.

  The basic idea of the present invention is that the force accompanying pressurization acts only in a mechanically closed system and does not act on a support mechanism system that supports this system, such as a support leg or base base. It is. Thereby, even if deformation or position fluctuation of the member itself related to pressurization occurs, a measuring device for measuring such change and position fluctuation is arranged on the base substrate, and based on the output of the measuring apparatus, It is possible to prevent a pressure distribution error caused by deformation of a portion related to pressurization and a positional deviation at the time of bonding.

With reference to FIG. 1, the pressurization apparatus of this invention is demonstrated.
A first frame (referred to as an upper pressure member in this example) 101 is composed of an upper pressing plate 102 and an upper support column 104, while a second frame (referred to as a lower pressure member in this example) 111 is a cylindrical bowl. It is a mold and has a structure having a flange 113. The flange portion 113 is mounted on a support leg 191 fixed to the base base 192. A pressure member (referred to as an upper pressure body in this example) 131 is attached to the upper pressure member 101, and an upper heater 141 is disposed according to the necessity of heating. A pressure transmitting member 165, a load cell 161, and a lower pressurizing body 151 are disposed on the other holding member 111 (referred to as a lower pressurizing member in this example), and a lower heater 142 is disposed according to the necessity of heating. Among these components, the pressure transmission member 165 may include a coarse movement mechanism that moves the lower pressurizing body 151 up and down.

  The pressurizing operation will be described. The substrates 172 and 182 to be pressed for bonding and the like are respectively held by the substrate holders 171 and 181, and are placed on the lower pressing body 151 in a state where the alignment is completed and superimposed. In order to pressurize, the upper support column 104 of the upper pressurizing member 101 is drawn toward the lower pressurizing member by the pressure source 121 and is sandwiched between the upper pressurizing member 102 and the lower pressurizing member 111. 182 is pressurized.

  The reason why the pressurizer having such a configuration provides a stable pressure distribution will be described next. The upper pressure member 101 and the lower pressure member 111 exert a pulling force on each other and press the substrates 172 and 182 together. As shown in FIG. 2, the applied pressure simply acts on the upper pressure member 102 and the lower pressure member 111 and slightly deforms the bottom surface of the upper pressure plate 102 and the lower pressure member, but the support leg 191 simply pressurizes. Since only the weight of the member is supported, the support leg is not deformed. If the support legs are not deformed, the force acting on the base base supporting the support legs is also constant, and the base base is not deformed. Therefore, a stable pressure distribution is obtained by measuring the deformation and position change of the upper and lower pressure members by the observation device 194 arranged on the base substrate, and adjusting the positions of the upper and lower pressure members based on the output result. Can be obtained. As the observation device 104, for example, a laser interferometer (ranging meter) 195 or the like can be used.

  Next, detailed operation of the present invention will be described. When controlling the applied pressure in the pressurizing apparatus of the present invention, the upper support column 104 is moved up and down by the pressure source 121. As this pressure source 121, the thing using the static pressure of the fluid as described in Fig.4 (a) can be used. An incompressible fluid is introduced into the cylinder 402 through the inlet 420, and the ram 410 in the cylinder 402 is moved up and down. As a result, the upper column 104 is moved up and down. Another embodiment for generating this pulling force is a combination of a ball screw and a motor as shown in FIG. The upper column 104 and the fringe portion 113 are connected via a ball screw, a motor, and a universal joint, and the upper column is pulled to the fringe portion by rotating the motor and moving the ball screw. A drive source with a simple mechanism and easy pressure control can be obtained. In addition, a guide mechanism 196 (FIG. 1) for movement is provided on the guide column 190 so that the upper column 104 can move stably up and down. The guide mechanism is a mechanism composed of a linear guide and a slider, and the linear guide is formed along the guide column 190 standing on the flange portion 113. The linear guide preferably uses a metal bearing in consideration of rigidity and the like. Since the guide column stands on the flange portion and the flange portion 113 does not deform when pressurized, the upper column 104 is stably guided and movable. Further, a guide holding mechanism 188 is attached to the inner peripheral portion of the flange 113 portion so as to suppress the position variation of the lower pressurizing body 151 due to pressurization, so that the position variation at the time of pressurization is minimized. .

  Generally used ceramic heaters and cartridge heaters can be used as the heaters 141 and 142 for pressurizing and heating the substrate in the pressurizing apparatus of the present invention. A temperature measuring element (not shown) for temperature control is attached to the heater, and it is possible to measure and control temperature change and temperature distribution.

  FIG. 3 shows an apparatus configuration of the pressurizing apparatus according to the present invention when the substrates are bonded in a non-oxidizing atmosphere, and a chamber 310 is provided in addition to the mechanism of FIG. This chamber may be a vacuum chamber or a chamber for taking in a purge gas in which oxygen is replaced with an inert gas.

  By the way, when using the pressure device as described above, the base base 192 and the upper and lower pressure members 131 and 151 may vibrate due to external factors, and the support legs and pressure members may be deformed or displaced. . In the present invention, in order to prevent such a phenomenon from occurring, at least one of the vibration damping members is provided between the support leg 191 and the base base 192, between the flange portion 113 and the support leg 191, and between the base base 192 and the floor. Is installed. FIG. 5 shows an example of the structure of the damping member arranged between the support leg 119 and the base base 192. A general air mount 502 or voice coil motor 504 whose internal pressure can be adjusted can be used. A combination of these is also possible. In FIG. 5A, the air mount 504 and the voice coil motor 502 capable of adjusting the internal pressure are arranged in series. In FIG. 5B, an air mount 504 and a voice coil motor 502 capable of adjusting the internal pressure are arranged in parallel. In either case, multiple accelerometers are mounted on the base and support legs, and vibration control is achieved by controlling the internal pressure of the air mount and the drive power of the voice coil motor based on the output of the accelerometer. Control becomes possible. When the air mount and the voice coil motor are used in combination, it is preferable to control each of them in consideration of the response characteristics. As a result, response time and response to the displacement range can be obtained.

Still another embodiment of the present invention will be described with reference to FIG. FIG. 6 is a flowchart showing a method for manufacturing a stacked semiconductor device to which the pressurizing apparatus of the present invention is applied.
S1: Prepare a predetermined number of wafers on which a plurality of semiconductor devices (semiconductor chips) are formed.
Here, the predetermined number corresponds to the number of stacked semiconductor devices. This process can be manufactured by a normal method for manufacturing a semiconductor device.
S2: The manufactured wafers are aligned and overlapped.
The following methods are known as alignment methods. (1) A method in which wafers to be superposed are brought close to each other, and alignment marks formed on the superposed surface are observed with an infrared microscope to align each other. (Refer to Unexamined-Japanese-Patent No. 2003-249425). (2) A method of observing the alignment marks on the wafer surfaces to be overlapped with a two-field microscope. (For example, refer to Japanese Patent Laid-Open No. 2000-332033) (3) A wafer is held in a wafer holder, the positional relationship between the wafer and the wafer holder is measured with respect to each wafer, and then the positional relationship between the wafer holders is measured. How to align each other. (See JP-A-7-14982).
S3: The electrodes on the superimposed wafers are joined together.
As for electrode bonding, pressure bonding with ultraviolet curable resin, thermosetting resin, electrode contact bonding with anisotropic conductive resin, method of melting and bonding solder micro bumps, cleaning the electrode surface between metals A method using diffusion of the above is used.
S4: A wafer laminate is formed.
The laminated wafer and the electrode bonded are thinned. A newly laminated and electrode bonded wafer generally has a thickness of 300 μm to 700 μm. The opposite surface of the wafer bonding surface is thinned by grinding and polishing.
When the thinning is completed, if there are more wafers to be laminated, steps S1 to S3 are repeated. Changes in the shape of the wafer (wafer stack) during these steps are simply shown in FIG. FIG. 7A shows a wafer on which a semiconductor device is formed. FIG. 7B shows a state in which two wafers (one may be a wafer laminate) are brought close to each other. For example, the alignment is performed by observing the mark 704 with two microscopes 702. FIG. 7C shows a state in which electrode joining is performed after two wafers are superimposed. FIG. 7D shows a wafer laminate produced by thinning the laminated wafers.
The method for manufacturing a stacked semiconductor device according to the present invention uses the pressurizing device according to any one of claims 1 to 7 in the step S3. Since the pressurizing apparatus of the present invention has a structure in which the applied pressure does not affect the stability of the pressurizing member as described above, uniform and stable electrode bonding can be obtained over the entire surface of the wafer.

  Increasing the density and driving speed of semiconductor devices is an inevitable demand in the industry, and the use of the present invention relating to the manufacturing method of such a semiconductor device is therefore inevitable in the industry.

The whole figure of the pressurization apparatus of the present invention is shown. The deformation | transformation of the flame | frame at the time of pressurization is shown. It is a general view of the pressurization apparatus provided with the chamber. The example of the drive device using the static pressure of the fluid which is an example of the attractive force is shown. The example of the vibration isolator used for this invention is shown. A manufacturing process of a stacked semiconductor device to which a pressurizing apparatus of the present invention is applied will be described. The change of the wafer in the manufacturing process of a laminated semiconductor device is shown.

Explanation of symbols

101 ··· First frame 102 ··· Upper face pressing plate 104 ··· Upper column 111 ··· Second frame 113 ··· Flange portion 121 ··· Pressure source 141 ··· ··· Upper heater 142 ··· Lower heater 151 ··· Lower pressure body 161 ··· Load cell 165 ··· Pressure transmitting members 172 and 182 ··· Bonding substrate 188 ··· Guide Holding mechanism 190 ···························································································· Laser rangefinder 196 · Chamber 402 ··· Cylinder 420 ··· Fluid inlet 502 ··· Air mount 504 ··· Voice coil motor 702 ··· Microscope 7 4 .... mark

Claims (8)

A pressurizing device for pressurizing a laminated substrate,
A pressure member attached to the first frame;
A holding member that is attached to the second frame and holds the substrate;
A driving device for pulling the first frame and the second frame;
Have
The first frame or the second frame has a flange portion;
The pressurizing device, wherein the flange portion is supported by a support leg standing on a base base. The pressurizing device according to claim 1,
The pressurizing device, wherein the driving device uses a static fluid pressure. The pressurizing device according to claim 1,
The pressurizing device, wherein the driving device is a motor for rotating a ball screw. The pressurizing device according to any one of claims 1 to 3,
A damping member for reducing vibration is disposed between at least one of the base base and the support leg, between the support leg and the flange portion, and between the base base and the floor portion supporting the base base. A pressure device characterized by that. A pressurizing device according to any one of claims 1 to 4,
The pressurizing device further comprising an observation device in which an interferometer is incorporated on the base substrate. A pressurizing device according to any one of claims 1 to 5,
A pressurizing apparatus further comprising a heater for heating the substrate. The pressurizing device according to any one of claims 1 to 6,
The pressurizing apparatus further comprising a chamber for replacing an atmosphere for pressurizing the substrate with an inert gas, or a chamber for maintaining a vacuum. A method for manufacturing a semiconductor device, comprising:
A wafer preparation step of preparing a predetermined number of wafers on which a plurality of semiconductor devices are formed;
Holding the wafer on a wafer holder and aligning each other to superimpose;
An electrode joining step for joining the electrodes to each other by pressurizing the stacked wafers;
A wafer laminate forming step of forming a wafer laminate by thinning the electrode-bonded wafer;
Have
A method of manufacturing a semiconductor device, wherein the pressurizing device according to claim 1 is used in the electrode bonding step.