JPH09153507A - Semiconductor device and machining method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid deforming outer leads and damaging a memory, etc., by fixing seals of the memory and the outer leads to a work holder of a grinder when the back face of the packaged memory is cut to make it thin. SOLUTION: A packaged memory to be machined is fixed by composite chucks of a work table 5 and evacuated by a vacuum pump to fix sealed part 1 of the memory to a fixing face of a porous ceramic 3 while outer leads 2 of the memory are fixed to the surface of a magnet 4 due to its magnetic force. The back face of the packaged memory is contacted with the working face of cup type diamond grindstone rotating at high speed to cut the back face to make thin the memory. This prevents such troubles as deforming of the grindstone and outer leads and damage of the memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device such as a logic or memory used in electronic equipment, a method of processing the same, and a processing device.

[0002]

2. Description of the Related Art Currently, RAM (Random Access Memory)
A memory card or a PC card having a built-in ROM or read only memory (ROM) has been developed and used as an external storage device of a computer or the like. In the future, it is attracting attention as a recording medium replacing a magnetic disk device, a CD-ROM, a magnetic tape and the like. However, the storage capacity of memory cards and PC cards currently on the market is lower than that of magnetic disk devices having the same volume, and further improvement in storage capacity is desired.

In order to improve the storage capacity of a memory card or a PC card, it is necessary to use a highly integrated semiconductor memory (hereinafter referred to as memory) or to increase the number of memories used. With regard to the former, the degree of integration has improved by 4 times in one generation (4 years) due to advances in LSI manufacturing equipment. However, in order to increase the degree of integration by one digit, 1
It takes nearly 0 years. Regarding the latter, in order to comply with a certain standard, it is necessary to reduce the size or the thickness of the built-in memory itself. However, since the area of the LSI chip increases as the degree of integration of the memory increases, it is difficult to make the memory extremely small. Therefore, in order to improve the memory capacity of the card, it is cost and technically advantageous to increase the packaging density of the memory by thinning and stacking the memory.

In order to achieve this, after sealing (packaging) the LIS chip with a resin material, the back surface of the LSI chip is processed together with the package resin,
We have developed a thin memory with a reduced thickness.

However, the technique of grinding and thinning the back surface of an LSI in a wafer state is described in "Super Precision Production Technology Series, Volume 2,
As described in "Practical Technology, Chapter 7, Section 1 Ultra Precision Surface Grinding Machine", it is established as a back-grinding technology, but the processing method and processing device for processing the memory after packaging as described above are now available. Was not established until.

[0006]

When the thickness of the packaged memory is reduced by grinding, the method of fixing the memory to be processed becomes a problem. The memory after packaging includes a portion (hereinafter referred to as a sealing portion) in which the LSI is sealed (packaged) with a resin material and a lead frame (hereinafter referred to as an outer lead) protruding from the sealing portion. Since the outer lead is very thin, it is easily deformed, and if it deforms during machining, it will come into contact with the tool, which is an obstacle to machining.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a processing method in which an outer lead does not become an obstacle during processing when a back surface of a memory after packaging is subjected to grinding processing to reduce the thickness, and a processing apparatus for automating this processing. I am trying.

[0008]

[Means for Solving the Problems] The above object is to fix a packaged memory to a work table of a grinding machine, and a sealing portion in which an LSI chip is covered with a resin material, and outer leads protruding from the sealing portion. It is achieved by separately fixing each to a work table and performing processing.

Further, the above object is to arrange a vacuum suction fixing jig and a magnet using porous ceramics on the fixing surface on a work table of a grinder, and to make a sealing portion of a memory a suction force of a vacuum pump and an outer lead. It is achieved by fixing each to the work table by the magnetic force of the magnet and processing.

Further, the above object is obtained by disposing a vacuum suction fixing jig on a work table of a grinder, fixing the sealing portion of the memory and the outer leads to the work table by the suction force of a vacuum pump, and performing processing. To be achieved.

Further, the above-mentioned object is to form a fixed portion made of a resin material on the outer lead for fixing the outer lead when the LSI is packaged with the resin material. Then, the sealing portion and the fixing portion of the memory are fixed to the work table by the suction force of the vacuum pump, and the work is performed.

According to the present invention, when the back surface of the memory after packaging is ground by grinding, the sealing portion of the memory to be processed and the outer leads to be processed are fixed to the work holders of the grinding machine. As a result, it is possible to prevent contact between the grinding wheel and the outer lead during processing, and prevent defects such as deformation of the outer lead and damage to the memory.

Further, in the present invention, the fixed surface made of porous ceramics and the magnet are arranged on the work table of the grinding machine, so that the sealing portion of the memory to be processed is made of porous ceramics by the suction force of the vacuum pump. The outer lead, which is a non-processed object, is fixed to the surface of the magnet by magnetic force. As a result, it is possible to prevent contact between the grinding wheel and the outer lead during processing, so that it is possible to prevent defects such as deformation of the outer lead and damage to the memory.

Further, according to the present invention, when the back surface of the memory after packaging is ground by grinding, the sealing portion of the memory to be processed and the outer leads to be processed are processed by the suction force of the vacuum pump. Fix on the fixed surface above. As a result, it is possible to prevent contact between the grinding wheel and the outer lead during processing, and prevent defects such as deformation of the outer lead and damage to the memory.

Further, according to the present invention, when the LSI is packaged with a resin material, a fixed portion made of a resin material is formed on the outer lead for fixing the outer lead. Then, when thinning the memory, by fixing the sealed portion of the memory that is the processing target and the fixed portion of the outer lead that is the non-processing target to the work table of the grinder by the suction force of the vacuum pump, It is possible to prevent contact between the grinding wheel, which is a tool, and the outer lead during processing. As a result, it is possible to prevent defects such as deformation of the outer leads and damage to the memory.

[0016]

Embodiments of the present invention will be described below.

First, the structure of the memory to be processed will be described. As a typical memory structure, there are a tab structure and a LOC structure (Lead On Chip). However, the effect of thinning is small in the tab structure memory, so it is excluded here. Hereinafter, description will be made for a memory having a LOC structure.
As shown in FIG. 1, the LOC structure memory has a lead frame 2 fixed to an LSI chip 6 with an adhesive tape 7,
A wire 8 is connected between the SI chip 6 and the lead frame 2, and these are sealed with a package resin. When the thinning process is performed on the memory having the LOC structure, the resin covering the back surface of the LSI chip 6 is first removed.
The back surface of the chip 6 (the surface on which no circuit is formed) is processed, and the entire memory is thinned.

Here, the following two types of memories were processed.

1. TSOP (Thin Small Outline Packag
e) Memory A cross-sectional view of a TLOC memory having a LOC structure is shown in FIG. T
The SOP memory is a typical thin memory, and the total thickness of the memory is 1 mm. The breakdown is that the resin 1 on the LSI chip 6 has a thickness of 0.4 mm, and the LSI chip 6 has a thickness of 0.4 mm.
Has a thickness of 0.3 mm, and the resin 1 under the LSI chip 6 has a thickness of 0.3 mm. The thickness of the lead frame 2 in this TSOP memory is 0.10 to 0.15 mm, and the material is often iron-based metal.

2. Ultra-thin memory Figure 5 shows the cross-sectional structure of an ultra-thin memory. This memory is
By utilizing the wireless bonding technology, the bump 1 is not provided between the lead frame 2 and the LSI chip 6 instead of the wire.
It is a memory connected by 1. This ultra-thin memory is thinner than the conventional one because it is thinner.
The thickness of the entire memory after packaging is 0.45mm due to the adoption of a lead frame with a thickness of mm and a memory structure in which the back surface of the LSI chip 6 is exposed from the resin 1.
Have achieved. In the case of this ultra-thin memory, since the back surface of the LSI chip 6 is exposed, the cut amount and the chip processing amount are substantially the same. Therefore, the LSI chip 6
It is easy to grasp the machining amount of. Further, since the back surface of the LSI chip 6 is exposed, the LSI chip 6 is not packaged during packaging.
Can be prevented from tilting. Therefore, LS in thinning processing
It is difficult for the processing amount of the I-chip 6 to vary. From the above, it is considered that the ultra-thin memory is suitable for thinning processing. However, since the thickness of the lead frame 2 is as thin as 0.05 mm, the lead frame is easily deformed during processing, which is a problem.

Next, the thin memory manufacturing process of the present invention will be described with reference to FIG. As a process, a thin film circuit is formed on the surface (mirror surface) of a 6-inch or 8-inch silicon wafer by a lithography technique or the like, and several tens of LSIs are formed on one silicon wafer. The thickness of the silicon wafer at this time is 0.5 to 0.6 in order to facilitate handling and prevent wafer cracking due to heat shock generated in the heat treatment process.
mm. However, in order to improve heat dissipation and reduce collector resistance of power transistors, it is necessary to thin the wafer after forming the thin film circuit. Therefore, the back surface of the wafer is ground (back surface grinding) to reduce the wafer thickness to 0.
3 to 0.4 mm. Then, dicing and pelletizing are performed to cut the LSI into chips. Next, fix the LSI chip to the lead frame (die bonding),
The terminals in the chip and the lead frame are connected by wire bonding. Then, the LSI chip and the lead frame are sealed (packaged) with resin. The memory thickness after packaging varies depending on the product, but is 0.4 to 1 mm depending on the thickness of the lead frame and resin. Then, the thinning process of the present invention is performed to reduce the thickness of the memory to 0.20 to 0.60 mm. Finally, the outer leads protruding from the package are cut and bent (lead molding).

As a processing method for the thinning process, since the LSI chip (silicon) which is a brittle material is processed, it is considered that the grinding process is suitable. The thinning of the memory by grinding will be described below. As a grinding method here, surface grinding using a cup-shaped grindstone was performed. Surface grinding using this cup-type grindstone has a better surface roughness than the surface grinding using disk-type grindstone,
It is considered to be suitable for the thinning processing method of the present invention. Further, also in the case of grinding using a cup-type grindstone, there are an in-feed grinding method and a rotary grinding method. As a difference between these two grinding methods, it is known that the in-feed grinding method can improve the surface roughness.
This is an advantageous processing method for a large workpiece such as a silicon wafer. Although either processing method can be applied to the thinning processing of the present invention, the in-feed grinding method having a good surface roughness is adopted here.

Examples will be described below.

Example 1 Thinning of a memory using a composite chuck composed of a vacuum chuck and a magnet chuck A structural diagram of the composite chuck is shown in FIG. In the composite chuck of the present invention, the sealing portion 1 is fixed by the vacuum chuck, and the outer lead 2 protruding from the sealing portion is fixed by the magnet. The structure of the composite chuck will be described below.

In the composite chuck, the porous ceramic chip 3 is embedded in the work table 5, and a vacuum suction pipe is provided at the bottom thereof. At this time, the upper surface of the porous ceramic chip 3 is arranged so as to protrude above the upper surface of the work table 5. Then, the upper surface of the porous ceramic chip 3 is ground on the machine of the grinder on which the work table 5 is installed, and the processed surface is used as the fixed surface of the memory sealing portion 1. Since the outer lead 2 is not fixed as it is, the magnet 4 is arranged as shown in FIG. 1 for fixing the outer lead 2.

Next, an example in which the composite chuck is thinned by an in-feed grinder having a work table will be described. FIG. 7 shows a block diagram of the processed in-feed grinder. This in-feed grinder is provided with a grinding wheel rotating shaft 16 for driving the cup-shaped diamond wheel 15 to rotate, a cutting table 12 for moving the grinding wheel rotating shaft up and down to make a cut in the memory, and a composite chuck. The work table 5 includes a work rotating shaft 13 for rotating and driving the work table 5, and a turntable 14 for moving the work rotating shaft between a working position and a mounting / removing position.

A processing method for thinning the memory by the above grinding machine will be described. First, several to several tens of post-packaged memories 17 to be processed are fixed to the composite chuck of the work table 5. At this time, the memory is arranged so that the surface of the memory is on the fixed surface side of the porous ceramics. When vacuum suction is performed by the vacuum pump in this state, the sealing portion 1 of the memory 17 is fixed to the fixed surface of the porous ceramics 3.
At this time, the outer leads 2 of the memory 17 are fixed to the surface of the magnet 4 by the magnetic force of the magnet 4. Then, by rotating the turntable 14 by 180 °, the memory 17 is moved below the cup-shaped diamond grindstone 15 which is a tool. Then, by moving (cutting) the cutting table 12 downward while the work rotating shaft 13 and the grinding wheel rotating shaft 16 are rotationally driven, the working surface of the cup-shaped diamond grinding wheel 10 rotating at high speed and the memory 17 after packaging. Contact the back surface of the memory 17, the back surface of the memory 17 is scraped, and processing proceeds.

In this thinning process, the working surface of the cup-shaped diamond grindstone 15 rotating at a high speed and the sealing portion of the memory 17 come into contact with each other, so that a force in two directions acts on the memory 17. One is a force that presses the memory against the fixed surface, and this force is called a grinding force normal force Fn. The other is a force acting in a direction perpendicular to the normal force of the grinding force, which is the tangential force Ft of the grinding force.
Call. The grinding forces Fn and Ft act only on the sealing portion 1 of the memory 17 that contacts the cup-shaped diamond grindstone 15, and do not act on the outer leads 2 that do not contact the cup-shaped diamond grindstone 15. From this, in the composite chuck of the present invention, the sealing portion 1 of the memory on which the grinding forces Fn and Ft act is firmly fixed by the suction force of the vacuum pump, and the outer portion on which the grinding forces Fn and Ft do not act. The lead 2 is softly fixed by the magnetic force of the magnet.

Using the above composite chuck, TSOP memory and ultra-thin memory were thinned under the following conditions.

Processing machine: In-feed grinder Grinding wheel: Cup-type metal bond diamond wheel (SD1500P75M) Grinding wheel rotation speed: 5000 r / min Work shaft rotation speed: 300 r / min Cutting speed: 50 μm / min Cutting depth: 0.5 mm (TSOP memory) 0.25 mm (ultra-thin memory) Processing memory quantity: 1 batch 8 pieces In addition, in order to check the effect of the composite chuck, the fixing method when the magnet of the composite chuck is removed and the outer lead 2 is not fixed ( The conventional chuck was also processed. The processing results are shown in Table 1.

[0031]

[Table 1]

In Table 1, the mark ◯ indicates the whole batch (8
This is the case when the memory can be thinned without any problem. Further, the mark X indicates that an abnormality has occurred during the thinning process.
The contents of this abnormality are a state in which the amount of processing of the memory is insufficient and the outer lead is deformed or the memory is damaged because the memory is removed from the fixed surface of the chuck during processing. It is considered that the occurrence of more than this processing is caused by a force larger than usual being applied to the memory. Then, since the outer lead of the memory in which the abnormality has occurred has a trace of contact with the grinding wheel, it is considered that the abnormality has occurred as follows.

In the grinding process, the grinding liquid is caused to flow at the contact point between the grinding wheel which is the tool and the memory which is the processing object. Then, the grinding fluid that has come into contact with the grinding wheel that rotates at a high speed scatters vigorously. Since the outer lead is not fixed in the conventional chuck, it is considered that the outer lead is elastically deformed in the thickness direction when the scattered grinding fluid hits the thin outer lead. The elastically deformed outer leads come into contact with the grinding wheel, so that the outer leads are caught in the grinding wheel. Therefore, it is considered that a large force acts on the memory and the memory comes off the fixing surface of the chuck.

Then, in the memory in which the abnormality has occurred, defects such as deformation of outer leads, cracking of the LSI chip 6 and chipping of the package resin occur.

In the conventional chuck, since the outer lead 2 is not fixed, a processing abnormality is likely to occur, and an abnormality occurs in 2 batches out of 5 batches in the TSOP memory and in all 5 batches in the ultra-thin memory. On the other hand, in the thinning process using the composite chuck, the TSOP memory and the ultra-thin memory could be thinned to a predetermined thickness without any problem. This is because the outer lead 2 can be prevented from contacting the cup-shaped diamond grindstone 15 by fixing the outer lead 2 to the magnet surface by magnetic force.

From the above results, it is necessary to fix the outer leads separately from the fixing of the sealing portion in the thinning process of the memory, and especially in the case of the ultra-thin memory having a thin lead frame of 0.05 mm. In this case, the method of fixing the outer leads will be important.

Example 2: Thinning process using a vacuum chuck to fix the sealing portion and outer lead In the above-mentioned Example 1, the sealing portion 1 of the memory is fixed by the suction force of the vacuum pump, and the outer lead 2 is fixed. The composite chuck fixed by the magnetic force of the magnet has been described. Here, a processing method of fixing the sealing portion 1 and the outer lead 2 of the memory with a vacuum chuck will be described.

A structural diagram of the vacuum chuck of the present invention is shown in FIG. The structure of the vacuum chuck is as follows. A porous ceramic chip 3 is embedded in the work table 5, and a vacuum suction pipe is provided at the bottom thereof. At this time, the upper surface of the porous ceramic chip 3 is arranged so as to protrude above the upper surface of the work table 5. Then, the upper surface of the porous ceramic chip 3 is ground on the machine of the grinder on which the work table 5 is installed, and the machined surface is used as the fixed surface of the memory sealing portion. Then, a pipe for vacuum suction is installed on the work table 5 for fixing the outer lead 2. However, even if vacuum suction is performed as it is, a gap is formed between the outer lead 2 and the work table 5, and the suction force is weakened. Therefore, the soft and easily deformable silicon rubber 9 is used as a spacer between the outer lead 2 and the work table 5 (adhesive fixing).
did. At this time, a hole is made in the silicon rubber 9 so that the suction force of the vacuum pump is transmitted to the outer lead 2. By disposing the silicone rubber 9 on the work table 5, the adhesion of the outer leads is improved and the outer leads can be firmly fixed.

When the memory after packaging is placed on the vacuum chuck having the above structure and vacuum suction is performed by the vacuum pump, the suction force acts between the porous ceramic chip 3 and the memory sealing portion and the vacuum suction force is exerted. Acts between the outer lead 2 and the silicone rubber 9, and the memory sealing portion 1 and the outer lead 2 are fixed to the work table 5.

Thinning was carried out by a grinder having a work table equipped with the vacuum chuck having the above structure. As the processing machine, the same in-feed grinder as in Example 1 shown in FIG. 7 was used. Then, under the processing conditions shown below, TSOP
5 batches of memory and ultra-thin memory were processed.

Processing machine: In-feed grinder Grinding wheel: Cup-type metal bond diamond wheel (SD1500P75M) Grinding wheel rotation speed: 5000 r / min Work shaft rotation speed: 300 r / min Cutting speed: 50 μm / min Cutting depth: 0.5 mm (TSOP memory) 0.25 mm (ultra-thin memory) Processing memory quantity: 1 batch 8 pieces As a result of processing, all 5 batches of TSOP memory and ultra-thin memory could be processed up to a predetermined thickness without any problem. . This is because the outer lead 2 can be prevented from coming into contact with the cup-shaped diamond grindstone by fixing the outer lead 2 with a vacuum suction force.

Embodiment 3: Thinning of a memory in which a fixed portion is provided on an outer lead Here, in order to smoothly perform a thinning process of a memory, a member for fixing the outer lead to the tip of the outer lead of the memory is used. A memory provided with a fixed portion and a method of processing the same will be described.

FIG. 3 shows a structural diagram of the memory and the vacuum chuck. This memory is characterized in that a fixed portion 10 is formed at the tip of the outer lead 2. The fixed portion 10 is a portion for vacuum-sucking the outer leads 2 during memory processing. Here, the same packaging resin as the constituent material of the memory sealing portion 1 was used as the constituent material of the fixed portion. This enables the fixed portion 10 to be formed in the memory packaging process. In addition, when the fixed portion 10 is formed, the fixing surface of the fixed portion 10 and the fixing surface of the memory sealing portion 1 are on the same plane, so that the package is easy and the fixing treatment is performed. Processing of ingredients becomes easy. And this fixed part 10 is
Because it is cut in the lead forming process after thinning,
The appearance of the final memory will be the same as before.

The structure of the vacuum chuck for fixing the memory in which the above-mentioned fixing portion is formed is as follows.

The porous ceramic chip 3 is embedded in the work table 5, and a vacuum suction pipe is provided at the bottom thereof. Then, the upper surface of the porous ceramic chip 3 and the upper surface of the work table 5 are ground on the machine of the grinding machine on which the work table 5 is installed. This allows
The processed surface of the porous ceramic chip 3 is the fixed surface of the memory sealing portion 1, and the processed surface of the work table 5 is the fixed portion 10.
Fixed surface. Then, a pipe for vacuum suction is installed on the work table 5 for fixing the fixed portion.

With respect to the vacuum chuck jig having the above structure, the memory having the fixed portion is arranged as shown in FIG. 3, and when vacuum suction is performed by the vacuum pump, the suction force is a porous ceramic chip. 3 and the memory sealing portion 1, and a vacuum suction force acts between the fixed portion 10 and the work table 5. As a result, the outer lead 2 having the memory sealing portion 1 and the fixed portion 10 is fixed to the work table 5.

Thinning was performed by a grinder having a work table equipped with the vacuum chuck having the above structure. As the processing machine, the same in-feed grinder as in Examples 1 and 2 shown in FIG. 7 was used. Then, according to the processing conditions shown below, TS
Five batches of OP memory and ultra-thin memory were processed.

Processing machine: In-feed grinder Grinding wheel: Cup-type metal bond diamond wheel (SD1500P75M) Grinding wheel rotation speed: 5000 r / min Work shaft rotation speed: 300 r / min Cutting speed: 50 μm / min Cutting depth: 0.5 mm (TSOP memory) 0.25 mm (ultra-thin memory) Processing memory quantity: 1 batch 8 pieces As a result of processing, all 5 batches of TSOP memory and ultra-thin memory can be processed up to the specified thickness without problems. It was This is because the outer lead 2 can be prevented from coming into contact with the cup-shaped diamond grindstone by fixing the outer lead 2 with a vacuum suction force.

Although the three methods of fixing the memory have been described above, there are other methods of fixing the memory sealing portion and the outer leads to the work table. One method is to use a heat-fusible wax, in which the wax liquefied by heating is interposed between the memory sealing portion and the work holder and between the outer lead and the work holder, and the wax is solidified. This is a method of fixing the sealing portion and the outer leads to the work table. Another one
One method is a fixing method using a heat-foamable adhesive sheet. This heat-foamable adhesive sheet has adhesiveness on both front and back surfaces, and one side of this sheet can be attached to a work table, and the memory can be fixed by attaching a sealing portion of the memory and outer leads to the other side. Then, by applying heat after the processing is completed, the adhesive sheet foams to reduce the adhesive strength, and the memory can be removed.

The above two fixing methods do not require a special chuck structure, but have the following problems. In the wax bonding, the wax adheres to the sealing portion of the memory and the outer leads, so cleaning with an organic solvent or the like is required. If the wax cannot be completely removed in this cleaning step, the wettability of the solder of the outer leads will deteriorate, which is a problem. In the heat-foamable adhesive sheet, since the sheet having low hardness is sandwiched between the memory and the work holder, the sheet is elastically deformed by the grinding force applied during processing. As a result, the processing accuracy of the memory deteriorates.
In addition, since these two fixing methods require heat to be attached / detached, the memory cannot be attached / detached on the machine of the grinding machine. Therefore, with this fixing method, it is difficult to automate the thinning process. On the other hand, according to the fixing method of the present invention, the memory can be attached / detached on the machine of the grinder, so that the thinning process can be automated.
Next, an example of automation of memory thinning processing using the fixing method of the present invention will be described.

Example 4 Automation of Memory Thinning Process An example of automating the memory thinning process using the composite chuck of the present invention will be described.

In order to apply the memory thinning processing to a mass production line, it is necessary to automate the processing and improve the throughput in the processing. Here, in order to improve the throughput, the thinning process is performed in a state where the five memories are connected by the outer leads 2 (a state where the individual pieces are not cut after the packaging). The composite chuck shown in FIG. 1 was also used for fixing the connection memory 21. However, in fixing the connected memory 21,
Porous ceramic chips are arranged at the positions where the five sealing parts are fixed, and a magnet is arranged around the chips. Further, here, an ultra-thin memory, which is difficult to process, is targeted for processing.

A conceptual diagram of the processing apparatus is shown in FIG. 8 and specifications are shown in Table 2.

[0054]

[Table 2]

In this automated semiconductor processing apparatus, the in-feed grinding machine used in the first, second and third embodiments is provided with an automatic loading / unloading function and the like. As a configuration added to the in-feed grinder, a belt conveyor 20 for conveying the memory, an index table 19 for arranging the memory, a loader 18 for moving the memory from the belt conveyor 20 to the index table 19, and a memory arranged for the index table are provided. A conveyor 23 conveys the work table, and an unloader 22 moves the memory from the index table 19 to the belt conveyor 20.

The main specifications of the apparatus are as follows.

Static pressure air bearings were used for the grinding wheel shaft and the work rotating shaft. A function (orientation function) that stops the rotation of the work table at the same position is added to the work rotation axis. This is a function in which a rotary encoder is arranged at the end of the workpiece rotation shaft and the stop position of the motor is controlled by a position signal from this rotary encoder. By adding this function to the work rotating shaft, it is possible to prevent the displacement when fixing the memory to the fixed surface of the work table.

A high-speed and highly accurate cam type is used for the loader and unloader that supply and discharge the memory to and from the index table by rotating the arm 90 °. A vacuum chuck is used to fix the memory to the arm tip, and the attachment / detachment is controlled by turning on / off the electromagnetic valve. By using such a loader / unloader, the supply / discharge of the memory to / from the index table is speeded up.

A rotary unit composed of a DD motor, a rotary encoder and a pneumatic brake was used as the index table positioning and driving source. Thereby, the index table attached to the rotary unit can be rotated and positioned with high accuracy. Also,
A magnetic sheet was attached to the upper surface of the index table on which the memories are arranged, and the outer leads of the memory are softly fixed to prevent the memory from being displaced due to the rotation of the index table.

In the thinning process of the memory, pure water is used as the working liquid and the cleaning liquid. Therefore, stainless steel was used as the pure water specification for the portion where the machining fluid is scattered.

Chips adhere to the processed memory.
Therefore, we have made possible automatic cleaning and drying on the work table. This is achieved by disposing pure water and air nozzles on the work table, flowing pure water into the memory during cleaning, and blowing dry air onto the memory during drying.

In the thinning process of the memory, the precision of the thickness of the processed memory is required. Therefore, an in-process processing amount sensing function was added to measure the thickness of the memory being processed in-process and feed back the thickness data to process the memory to a specified thickness accuracy. This can be realized by the following configuration. A capacitance type sensor is arranged in the vicinity of the surface to be processed of the memory fixed to the work table. When the processing advances and the back surface of the LSI chip is processed, the distance between the measurement surface of the sensor and the LSI chip can be measured by the capacitance type sensor because the LSI chip is a semiconductor. This makes it possible to grasp the LSI chip processing amount, and by feeding back this data to the NC controller of the processing apparatus, the memory can be processed to a predetermined thickness.

Next, the process of thinning the memory in the semiconductor processing apparatus will be described with reference to FIGS.
First, the connection memory 21 flowing by the belt conveyor 20 is vacuum-adsorbed and fixed to the arm tip of the loader 18. Then, the arm of the loader 18 is rotated by 90 ° and the vacuum suction is turned off to place the connection memory 21 on the index table 19, and the index table 19 is rotated by 90 °. By repeating this operation, four linked memories 21 are arranged on the index table 19. Next, the connection memory 21 on the index table 19 is transferred to the work table 5 by the carrier 23.
Transport to Next, turn on the vacuum chuck of the work table.
N, and the sealing portion of the connected memory is fixed. At this time, the outer leads of the connection memory 21 are fixed to the magnets arranged around the fixing surface for the sealing portion. Next, the turntable 14 is rotated by 180 ° to move the connection memory 21 from the attachment / detachment position to the processing position. Then, the cup-shaped diamond grindstone 15 is used to perform thinning processing. After the processing is completed, the turntable 14 is rotated 180 ° to move the thinned connection memory 21 from the processing position to the attachment / detachment position. Then, the workpiece rotating shaft 13 is rotated, and pure water is caused to flow through the rotating connected memory 21 to wash the chips attached to the memory. Next, in order to dry the pure water attached to the connection memory 21, air blowing is performed. Then, after the air blow is finished, the rotation of the work shaft is stopped. At this time, make sure that the rotation of the work table always stops at the same position (use a work rotation axis with an orientation function). Next, the vacuum chuck on the work table is turned off. At this time, although some back pressure is applied to the vacuum chuck, the position of the connection memory 21 does not shift because the outer lead is fixed to the magnet surface. Next, the carrier 23
The linked memory 21 processed by is transferred from the work table to the index table 19. Then, the connection memory 21 processed by the unloader 22 is used as the work table 1
9 to the belt conveyor 20.

The processing steps in the semiconductor processing apparatus have been described above. Then, while one of the two work tables is performing processing at the processing position, the other work table at the attaching / detaching position can perform continuous processing by performing steps 7 to 13 and 1 to 3, thereby improving efficiency. Can be thinned well. An ultra-thin memory (connected memory) was automatically processed using the above-mentioned semiconductor processing apparatus, but no abnormal processing such as deformation of outer leads and memory damage occurred.

By disposing the composite chuck on the work table of the semiconductor processing apparatus, it was possible to prevent contact between the outer lead and the grinding wheel, and to prevent defects due to processing abnormalities. In addition, by applying this composite chuck, the memory after packaging can be mounted on the machine and can be automated.

[0066]

According to the present invention, when the back surface of the memory after packaging is ground by grinding to reduce the thickness of the memory, the sealing portion of the memory to be processed and the outer leads to be processed are respectively the work of the grinder. By fixing to the holder, it is possible to prevent contact between the grinding wheel and the outer lead during processing. As a result, it is possible to prevent defects such as deformation of the outer leads and damage to the memory during the memory thinning process.

[Brief description of the drawings]

FIG. 1 shows a structural diagram of a memory chucking composite chuck using a vacuum chuck using a porous ceramics and a magnet on the fixing surface of the present invention.

FIG. 2 is a structural diagram of a vacuum chuck for fixing a memory according to the present invention.

FIG. 3 shows a memory in which an outer lead of the present invention is provided with a fixed portion for a vacuum chuck, and a structural diagram of the vacuum chuck for fixing the memory.

FIG. 4 shows a TSOP memory sectional view (LOC structure).

FIG. 5 shows a cross-sectional view (LOC structure) of an ultra-thin memory.

FIG. 6 shows a manufacturing process of a thin memory.

FIG. 7 shows a structural diagram of an in-feed grinder using the memory fixing method of the present invention.

FIG. 8: Automatic loading using the memory fixing method of the present invention
The structure of the semiconductor processing apparatus with an unloading function is shown.

FIG. 9 shows a thinning process.

[Explanation of symbols]

1 ... Memory sealing part, 2 ... Outer lead (lead frame) 3 ... Porous ceramics, 4 ... Magnet 5 ... Work table, 6 ... LSI chip 7 ... Tape, 8 ... Wire 9 ... Silicon rubber, 10 ... Outer lead fixing Fixed parts for use 11 ... Bumps, 12 ... Cutting table 13 ... Workpiece rotating shaft, 14 ... Turntable 15 ... Grinding grindstone (cup type diamond grindstone) 16 ... Grinding grindstone rotating shaft, 17 ... Memory after packaging (single) 18 ... Loader, 19 ... Index table 20 ... Belt conveyor, 21 ... Memory after packaging (connection) 22 ... Unloader, 23 ... Conveyor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location H01L 23/28 H01L 23/28 T (72) Inventor Yuu Yoshida 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Bunch Co., Ltd., Hitachi, Ltd.

Claims (8)

[Claims] 1. A processing method for thinning a sealing material and an LSI chip by grinding a semiconductor device in which a lead frame and an LSI chip are sealed, on a surface of the LSI chip on which a circuit is not formed. The part of the chip covered with the encapsulation material is fixed to a fixing jig, and the lead frame protruding from the encapsulation material is fixed to a dedicated fixing jig to prevent the lead frame from fluctuating during processing and encapsulating material. And a method for processing a semiconductor device, which comprises processing an LSI chip. 2. The method for processing a semiconductor device according to claim 1, wherein a portion of the LSI chip covered with a sealing material is fixed to a fixing surface made of porous ceramics by a suction force of a vacuum suction device, A semiconductor device characterized in that a lead frame protruding from a magnetic field is fixed to a magnet surface arranged beside the fixing surface by magnetic force, and a sealing material and an LSI chip are processed while preventing the lead frame from changing during processing. Processing method. 3. The method of processing a semiconductor device according to claim 1, wherein a portion of the LSI chip covered with a sealing material is fixed to a fixed surface by a suction force of a vacuum suction device, and a lead frame protruding from the sealing material is formed. A method for processing a semiconductor device, comprising fixing to a magnet surface arranged beside the fixing surface by magnetic force, and processing the sealing material and the LSI chip while preventing the lead frame from changing during processing. 4. The method for processing a semiconductor device according to claim 1, wherein a portion of the LSI chip covered with a sealing material and a lead frame protruding from the sealing material are fixed to a fixing surface by a suction force of a vacuum suction device, A method for processing a semiconductor device, which comprises processing an encapsulating material and an LSI chip while preventing a lead frame from changing during processing. 5. A semiconductor device in which a lead frame and an LSI chip are sealed, wherein a fixed portion made of a sealing material is formed on a lead frame protruding from a sealing material. 6. The semiconductor device according to claim 5, wherein a portion of the LSI chip covered with a sealing material and a fixed portion formed on a lead frame protruding from the sealing material are fixed to a fixing surface by a suction force of a vacuum suction device. A method for processing a semiconductor device, which comprises fixing and processing a sealing material and an LSI chip while preventing a lead frame from changing during processing. 7. A grinding machine for thinning a sealing material and an LSI chip by subjecting a semiconductor device, in which a lead frame and an LSI chip are sealed, to a surface of the LSI chip on which a circuit is not formed to perform grinding processing. , A fixing jig having means for fixing the portion of the LSI chip covered with the sealing material and the lead frame protruding from the sealing material, and a rotary shaft for rotationally driving a grinding wheel that is a tool, A semiconductor processing apparatus, comprising: a rotation shaft for rotationally driving the target semiconductor device. 8. A grinding machine for thinning a sealing material and an LSI chip by subjecting a semiconductor device, in which a lead frame and an LSI chip are sealed, to a surface of the LSI chip on which a circuit is not formed to perform grinding processing. , A fixing jig having means for fixing the portion of the LSI chip covered with the sealing material and the lead frame protruding from the sealing material, and a rotary shaft for rotationally driving a grinding wheel that is a tool, A semiconductor processing apparatus comprising a rotating shaft for rotationally driving the target semiconductor device, and a mounting / demounting device for automatically mounting / dismounting the processing target semiconductor device to / from a fixing jig.