JPH0799145A - Production control method and device - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the accuracy of the production control method for high-mix low-volume production. [Structure] In a preceding wafer number determination step 66, a preceding number corresponding to a predetermined order 65 is determined. In the lot forming process 67 of the preceding wafer group, a small number of wafers are extracted from each of the stored lot groups to form a group of the preceding wafers, and the wafer is put into the custom process 64. After finishing the custom process 64 and the wafer inspection process 68, a yield is calculated for each lot of the preceding wafer group in a lot yield calculation process 69. In the subsequent orders 70, the optimum number of inputs corresponding to the number of orders is
The yield corresponding to the optimum value is obtained from the yield group obtained for each lot for the preceding work group, and the lot corresponding to the used yield is input to the custom process 64. [Effect] Since the yield of each stored lot is confirmed by the preceding work group during the production of the custom process,
The influence of yield variation can be suppressed and the control accuracy can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to production control technology, and more particularly to
Control technology for production methods of custom products and semi-custom products, such as mask ROM (read only memory) and
The present invention relates to a technique effectively used for a production method of a product such as a specially ordered semiconductor integrated circuit device (hereinafter referred to as ASIC) that requires high-mix low-volume production.

[0002]

2. Description of the Related Art Among production control methods of semiconductor wafers (hereinafter referred to as "wafers") as works in a semiconductor device manufacturing process, a large number of small kinds of semiconductor memory devices (memory) such as RAM (random access memory). For products suitable for production, it is possible to adopt a prospective production control method or a long-term planned order production control method.

However, with regard to products that are required to be produced in small lots in various types, such as mask ROM (read only memory) and ASIC, not only are there a wide variety of orders, but also the order period is short and the order volume varies. Since it frequently occurs, it is not possible to simply adopt the forecast production control method or the long-term planned order production control method.

Therefore, such mask ROM and ASI
For the production of wafers such as C, it is possible to adopt the following production control method. In other words, first, products that require high-mix low-volume production of mask ROMs (hereinafter,
It is called a mask ROM. The method of producing wafers is classified into a master process, a storage process, and a custom process. In the master process, the wafer group is sequentially organized into a lot of lots until the process process in which the prospective production of the mask ROM wafer can be proceeded, and the production is advanced by the prospective production control method. Wafers that are expectedly produced in the master process are stored in the work stocker while maintaining the previous lot. After that, when an actual order is received, the number of wafers corresponding to the number of ordered products is calculated, lots corresponding to the number of wafers are selected, lots are put into a custom process, and a predetermined custom process is performed. Properly produced.

The number of wafers X, which corresponds to the number of ordered products, is calculated by the following equation (1). X = P / N × Y (1) In the formula (1), P is the required number of pellets (corresponding to the number calculated from the number of ordered products in consideration of the post-process yield and the amount in process), N Is the number of pellets obtained per wafer,
Y is the average yield in each lot of wafer groups produced in the past.

Note that Japanese Patent Laid-Open No. 55-161701 and Japanese Patent Laid-Open No. 56-114650 are examples of a method for controlling a high-mix low-volume production.

[0007]

However, in the above-described mask ROM wafer production control method, the average yield of lots of wafer groups produced in the past is used when calculating the number of wafers input to the custom process. Therefore, if there is a significant difference between the actual yield of lots of wafers that will be put into the custom process and the average yield of lots of wafers produced in the past,
Occasionally, the desired production cannot be secured. That is,
The difference between the actual production volume and the expected production volume increases.

In other words, the present inventor has clarified that the above-mentioned production control method has a problem that the precision of production control is low. If the precision of the production control method is low, the product must be produced in a large amount in anticipation of that, and the excessive production must be eventually discarded. Therefore, the productivity is lowered and the profit rate is lowered.

Incidentally, the cause of the deterioration of the production control accuracy in the above-mentioned production control method is the disagreement between the past yield and the actual yield.
The yield varies between lots. That is,
The yield is different for each lot. The difference in the yield between the lots is due to the difference in the materials (wafer crystals, etc.) of the wafers that make up each lot, and the manufacturing processes (such as the manufacturing equipment used and manufacturing conditions) that the lots undergo. ) Caused by the difference. Therefore, the yield difference between each lot is
Even if the difference width can be reduced, it cannot be eliminated.

An object of the present invention is to provide a production control technique suitable for high-mix low-volume production which can improve production control accuracy.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0012]

The typical ones of the inventions disclosed in the present application will be outlined below.

That is, a master process in which a large number of works are sequentially organized into a large number of lots and are prospectively produced,
The work process that is produced in the master process is stored while maintaining the previous lot, and the work process that is stored in response to an order is input and produced while maintaining the previous lot. A production control method for a production method comprising a custom process to be performed, wherein the preceding number corresponding to the number of orders at any time is determined in the custom process, and This determined number of workpieces is extracted from each lot for each small number and prepared, and the extracted preceding number of workpieces is put into the custom process for production, and after the custom process is completed, the preceding work is performed in the inspection process. The yield is calculated for each lot for each group, and the optimum number of inputs to the custom process corresponding to the number of orders is calculated for the preceding work group when receiving subsequent orders. The yield corresponding to the optimum value is used from the yield group obtained for each lot, and the lot corresponding to the used yield is selected and input to the custom process for that lot. Is characterized by.

[0014]

According to the above-mentioned means, in the production in the custom process, the yield of each stored lot is preliminarily confirmed by the preceding work group, so that the influence of the variation of the yield is suppressed. can do. That is, first, it is possible to suppress the influence of the difference in yield due to the nature of the work itself forming each lot. It is not possible to completely eliminate the effect of the difference in yield due to the difference in the process through which the work goes through in the custom process, but the influence of the difference in yield due to the difference in the process in the master process is confirmed by the preceding work group, so it should be eliminated. You can Therefore, the influence of the difference in the yield due to the difference in the process through which the work passes can be reduced to half or suppressed.

[0015]

FIG. 1 is a process diagram showing a wafer production control method according to an embodiment of the present invention. FIG. 2 is a block diagram showing a wafer production control apparatus according to an embodiment of the present invention.
FIG. 3 is a schematic view showing a knitting apparatus for the preceding wafer group used therein, FIG. 4 is a perspective view thereof, and FIG. 5 is a schematic view showing a knitting method for the preceding wafer group. FIG. 6 is a schematic plan view showing a wafer, and FIG. 7 is a perspective view showing a cassette.

In this embodiment, the production control method according to the present invention uses a mask ROM wafer (hereinafter referred to as a wafer).
Used to control the production method of. This wafer production method can be roughly classified into a master process, a storage process, and a custom process. In the master process, the wafer group is sequentially organized into lots of lots and the production is advanced by the prospective production control method until a process step in which the prospective production of the mask ROM wafer can be advanced.

In the storage process, with the wafer group produced in the master process presumed to maintain the previous lot,
It is stored in the wafer stocker which is the work stocker. In the custom process, when an order is actually received, the wafer group of each lot stored in the wafer stocker is put into the process by a control method described later, and the custom process is appropriately made to order.

In this embodiment, the production control device 50 according to the present invention is configured to control the method for producing a mask ROM wafer. The wafer production control device 50 includes an identification code assigning device 51, a master process wafer group lot forming device 52, a wafer stocker 53,
The preceding wafer group organization device 11, the first data processing device 40 constructed by a computer or the like, the wafer inspection device 55, and the second data processing device 56 constructed by a computer or the like are provided.

The identification code assigning device 51 is configured to attach a wafer identification code including an optically readable lot identification code to a large number of works in the master process. Master process wafer group lot organization device 5
2 is configured to read a lot identification code in a master process and organize a wafer group into a designated lot. The configuration of the lot forming device 52 for the master process wafer group is the same as the configuration of the lot forming device for the preceding wafer group, which will be described later, and thus detailed description thereof will be omitted.

The wafer stocker 53 is configured to store the wafer group in a state where each lot is maintained in the storage step after the master step. The wafer stocker 53 is also configured to dispense a cassette containing a lot designated by a command from the data processing device.

In the custom process, the preceding wafer group organization device 11 reads the lot identification code attached to each lot of wafers stored in the wafer stocker 53, stores the lot identification code for each lot, and stores the wafers from each lot. Are arranged to form a group of preceding wafers.

The first data processing unit 40 determines the preceding number corresponding to the ordered number at any time in the custom process, and also acts as the preceding wafer group knitting device to select from the wafer groups stored in the wafer stocker 53. The determined number of wafers is extracted from each lot for each small number and prepared, and the extracted preceding number of wafers is put into the process 54 of the custom process for production.

The wafer inspection device 55 is composed of a wafer prober or the like and is arranged in the wafer inspection process. After the process 54 in the custom process is completed, the yield is obtained for each lot of the preceding wafer group, and
The yield of each lot is transmitted to the second data processing device 56.

The second data processing device 56 determines the optimum number of sheets to be supplied to the custom process corresponding to the number of ordered wafers in the yield group obtained for each lot for the preceding wafer group in the build-to-order manufacturing after the production of the preceding wafer group. Of these, the yield that matches the optimum value is used, and the lot corresponding to the yield used is specified, and the wafer stocker 5
It is configured so as to be input from 3 to the custom process.

In this embodiment, the mask ROM wafer 1 as a work has a wafer identification code (hereinafter simply referred to as a work identification code) as shown in FIG.
It is called an identification code. ) 4 is arranged at a position opposite to the orientation flat 3 on the first main surface 2 of the wafer 1, and is drawn by numbers and English letters by using a means such as an etching method or a laser engraving method. .
In this embodiment, the identification code 4 is an identification code (hereinafter, referred to as a lot code) 5 that displays the lot number of the wafer 1 and an identification code (hereinafter, a wafer code) that is displayed for each wafer number in the lot. 6 and 6.

A lot forming apparatus 11 for a preceding wafer group (hereinafter sometimes referred to as a lot forming apparatus) 11 used in the wafer production control method according to this embodiment is a machine frame 12 formed in a substantially box shape. On the machine frame 12, four loading / unloading stations 13, 14, 15, 16 and an articulated robot (hereinafter referred to as a robot) 21 as a transfer device are provided.
And an identification code reading device 30 are provided respectively.

The first station 13 is arranged at one side position in the central portion of the machine frame 12. The second station 14, the third station 15 and the fourth station 16 are arranged side by side on one side of the machine frame 12. In FIG. 3, each station 13, 14, 1 is represented as typically represented by the first station 13.
Reference numerals 5 and 16 are provided with an elevator 18 controlled by a controller 19 so that one wafer 1 can be handed over to an empty cassette 20 placed on the elevator 18 under the control of the elevator 18. Has been done.

By the way, as shown in FIG. 7, each cassette 20 has a plurality of holding grooves (slots) S1 to S.
A large number of wafers (25 in this embodiment) are arranged in a row, and a plurality of wafers (one lot in this embodiment) are inserted into the holding grooves. Are to be stored in a regularly arranged state.

The robot 21 as a transfer device has a machine frame 12
It is arranged at one side position in the upper central portion. The robot 21 has an arm 2 controlled by a controller 22.
3, a grip 24 for holding the wafer 1 is provided at the tip of the arm 23. By operating the arm 23 controlled by the controller 22, the robot 21 picks up one wafer 1 from the actual cassette at the predetermined station at the grip 24 and conveys it to the identification code reading device 30, and further, the wafer 1 is identified by the identification code. It is configured to be conveyed from the reading device 30 to another station and accommodated in a slot of an empty cassette held in the station.

The identification code reader 30 includes a machine frame 12
It is arranged at a substantially central position in the upper rear portion. The identification code reading device 30 is provided with an alignment device 31, and the alignment device 31 is configured to hold the wafer 1 and perform alignment work and yawing correction work via the controller 32. There is.

A stand is erected on the machine frame 12 on the alignment device 31, and the lighting device 3 is mounted on the stand.
3 and a television camera 35 as an image capturing device are supported. A light source 34 is optically connected to the illuminating device 33, and the light from the light source 34 is dimmed by the illuminating device 33 toward the stage of the alignment device 31 for irradiation. The television camera 35 is configured to capture the identification codes 4 and 8 of the wafer 1 illuminated on the stage of the alignment apparatus 31.

An identification code recognition device 36 is electrically connected to the television camera 35. The identification code recognition device 36 is composed of an image processing device and the like, and the television camera 3
The identification codes 4 and 8 attached to the wafer 1 can be recognized based on the image pickup signal from the wafer 5. A monitor 37 is connected to the identification code recognizing device 36, and the monitor 37 monitors the shooting condition of the television camera 35.

Further, the identification code recognizing device 36 is connected with a memory 38 as a recording means for sequentially recording the identification code, and the memory 38 is provided with the identification codes 4 and 8 recognized by the identification code recognizing device 36. Are sequentially recorded. This memory 38
Is a data processing device 4 constructed from a computer or the like
It is connected to 0, and the data recorded in the memory 38 is read by the data processing device 40 at any time. The memory 38 may be installed on the data processing device 40 side.

In the present embodiment, the data processing device 40 is configured to execute various calculations, collation and command operations, which will be described later, based on the data read from the memory 38.

Here, the lot organization device 1 according to the above configuration
The identification code reading operation of No. 1 will be described in advance. In the wafer lot formation device 11, the actual cassette 17 in which the wafers 1 that have passed through the master process are stored is, for example, the first station 1 out of the four stations 13 to 16.
3 on the elevator 18. When the real cassette 17 is supplied onto the elevator 18 of the first station 13, the robot 21 operates the arm 23 to address one wafer 1 in the real cassette 17, holds it with the grip 24, and takes it out from the real cassette 17. , And is sequentially supplied to the stage 31 of the first identification code reading device 30.

On the stage of the alignment device 31, the wafer 1 is supported horizontally, and the illumination device 33 of the identification code reading device 30 and the television camera 3 are provided.
Faced with 5. When the wafer 1 is directly faced to the television camera 35, the identification code reading device 30 reads the identification code 4.

The identification code 4 thus read
Is recorded in the memory 38 connected to the identification code recognition device 36. Then, based on this recorded data, the lot formation work of the preceding wafer group is carried out as described later.

When the identification code 4 is read,
The wafer 1 is, for example, the second station 1 designated by the controller 22 among the first to fourth stations 13 to 16.
4 is transferred by the robot 21 to the predetermined slot Sn in the empty cassette 20 supplied onto the elevator 18 of the station 14 as shown in FIG.

Now, for example, the identification code reading device 30
When the number of the wafer code 6 of the identification code 4 read by N is N0.1, the elevator 18 is sent one pitch by the instruction of the controller 19 of the second station 14 that has been transported, and the elevator 18 is moved to the first position in the empty cassette 20. 1
The slot S1 is set to the insertion operation position S0. Then, when the first slot S1 is set to the insertion operation position, the wafer code N transferred by the robot 21.
O. One wafer 1 is inserted into this first slot S1.

Next, when the number of the wafer code 6 of the identification code 4 read by the identification code reading device 30 is N0.3, the second station 1
In response to a command from the controller 19 of No. 4, the elevator 18 is further fed by two pitches, and the third slot S3 of the empty cassette 20 is set to the insertion operation position S0. Subsequently, the wafer code N transferred by the robot 21
The wafer 1 of 0.3 is inserted into the third slot S3.

Next, the number of the wafer code 6 of the identification code 4 read by the identification code reading device 30 is NO. If it is 2, the elevator 18 is sent so as to be returned by one pitch according to a command from the controller 19 of the second station 14, and the second in the empty cassette 20 is sent.
The slot S2 is set to the insertion operation position S0. Subsequently, the wafer code N transferred by the robot 21
The wafer 1 of 0.2 is inserted into the second slot S2.

By repeating such an operation, the wafer 1 group of the designated wafer code 6 is moved into the empty cassette 20 of the second station 14 for each wafer code 6.
It is also possible to arrange and accommodate the slots according to the slot numbers. That is, in such a case, the wafer of wafer code N0.1 is stored in the first slot S1.
The wafer having the wafer code N0.2 is placed in the second slot S2, and the wafer code N0. That is, n wafers have been inserted.

With the above operation, the identification code reading work and the lot organization work are carried out. At the same time as these works, the processing of each wafer and the lot in the memory 38 are performed in the memory 38 based on the reading data of the identification code reading device 30. A history file is virtually created (not shown).

Next, the operation of the wafer production control device 50 having the above-described structure will be described, so that the wafer production control method 60 according to one embodiment of the present invention is used by the wafer lot organization device 11. The case will be described with reference to the process chart of FIG.

Further, here, a mask ROM which is a product
A case will be described in which the wafer lot organization device 11 having the above-described configuration is used to perform a wafer lot organization method on a wafer group for which a (read-only memory) is manufactured. As described above, the mask ROM may be produced in small quantities in various types, and in the so-called pre-process, the pre-process is shared as a master process or base process, and the post-process is individualized or dedicated as a custom process. Has been converted.

As shown in FIG. 1, the mask ROM
Before the wafer is put into the master process 62 of the production line, the identification code 4 including the lot code 5 and the wafer code 6 is attached to each wafer 1 in the identification code attaching and cassette lot packing step 61. Or suitable means such as laser engraving or the like. At this time, the above-mentioned identification code attaching device 5
A lot formation device 52 for 1 and master process wafers is used.

25 wafers 1 per lot
Are stored in each cassette for each lot code 5. For normal wafer production such as RAM wafers, this 1
Although 25 wafers per lot are manufactured in an integrated manner, as described above, in the production of mask ROM wafers, it is desirable to implement a production control method according to an order in a custom process.

Therefore, in the present embodiment, the mask RO
In the production of M wafers, the processes having the same production process are summarized as a master process 62, and the master process proceeds with the prospective production. Then, the custom process 6 is a process for individualizing or specializing the production process.
In summary, the custom process 64 advances production by a production control method according to the order received.

In the step of attaching the identification code and the lot packing in the cassette 61, the identification code 4 is attached, and
The wafer group organized into a predetermined lot is put into the master process 62 in a state where each lot is maintained, and is prospectively produced by each process in the master process 62. As described above, in the master process 62, the production is advanced by the prospective production control method until the process step in which the prospective production can be proceeded for the mask ROM wafer.

As shown in FIG. 1, the master process 6
In the storage step 63, the wafer group produced in 2 is stored in the wafer stocker 53 while maintaining the lot composition organized before the master step.

On the other hand, as shown in FIG. 1, when a predetermined order 65 is received, the number of preceding wafers is determined in the preceding wafer number determining step 66. The time when the predetermined order is received means a time when the yield of each lot needs to be confirmed in advance in the custom process 64. For example, this may be the time of the first order receipt, the time when all lot groups of the wafer group produced in advance, which will be described later, are all gone, or the lot group is small.

When this predetermined order 65 is received, the first data processing unit 40 calculates the number Xa of preceding wafer groups from the following equation (2). Xa = P / N × Y (2) In the formula (2), P is the required number of pellets and N is the wafer 1.
The number of obtained pellets obtained from one sheet, Y is the average yield of each lot in past production.

When the number Xa of the preceding wafer group is thus determined, the preceding wafer group is knitted in the lot forming process 67 of the preceding wafer group. At this time, the lot forming device 11 for the preceding wafer group is used, and a small number of wafers are taken out from the lots stored in the wafer stocker 53 to form the preceding wafer group.

Next, a lot forming method for the preceding wafer group will be described. Here, a case will be described as an example where one wafer is extracted from each of three lots and one preceding wafer group is knitted.

That is, as shown in FIG.
O. The number of wafers in the actual cassette (hereinafter referred to as the first actual cassette M1) accommodating the wafer group of one master lot is one.
No. One wafer in an actual cassette (hereinafter referred to as a second actual cassette M2) accommodating a wafer group of two master lots, and NO. One wafer in an actual cassette (hereinafter, referred to as a third actual cassette M3) accommodating a wafer group of three master lots is transferred to each empty cassette A, and one set of preceding wafer groups is synthesized. .

First, as shown in FIG. 5, the empty cassette A is set in the first station 13 of the lot forming apparatus 11. Also, the first actual cassette M1
Is set in the second station 14, the second actual cassette M2 is set in the third station 15, and the third actual cassette M3 is set in the fourth station 16.

At this time, the lot code 5 of the wafers to be accommodated in the empty cassette A of the synthesis destination and the number of wafers are input to the data processing device 40 as data on the lot of the synthesis destination. Further, the data processor 40 indicates that the lot code and the number of wafers to be transferred from the synthesizing first real cassette M1, second real cassette M2 and third real cassette M3 to the empty cassette D are the lots of the synthesizing source. Is entered as data about. .

Next, the second to fourth stations 14, 1
Actual cassette M set to 5 and 16 respectively
One wafer is delivered from 1, M2, and M3, and while the identification code 4 is sequentially read by the code reading device 30 described above, the number of wafers designated by the data processing device 40 is an empty cassette A as a synthesis destination. Will be transferred to each.

For example, in the first real cassette M1 set in the second station 14, the NO. No. 1 in the empty cassette A set in the first station after the identification code 4 of the wafer No. 1 is read by the reading device 30. It is transferred to 1 slot. Further, the NO. 2 in the second actual cassette M2 set in the third station. After the wafer 1 of which the identification code 4 is read by the reading device 30, the empty cassette A
NO. Moved to 2 slots. Further, the No. 3 in the third actual cassette M3 set in the fourth station. No. 1 of the empty cassette D is read after the identification code 4 of the wafer 1 is read by the reading device 30. Three
Transferred to a slot.

A set of preceding wafers organized in this way is processed by a custom process 64, as shown in FIG.
Be thrown into. In the custom process 64, the preceding wafer group is produced by a predetermined custom process and then sent to the wafer inspection process 68.

In the wafer inspection step 68, the preceding wafer group is inspected for each wafer. The wafer inspection data is transmitted to the second data processing device 56.

Next, as shown in FIG. 1, in the lot yield calculation step 69 of the preceding wafer group, the yield of the preceding wafer group is calculated for each lot unit previously organized. This calculation is executed by the second data processing device 56, and the yields Y ₁ , Y ₂ and Y ₃ are stored in the memory for each lot. Here, Y ₁ is NO. Yield calculated for one lot, Y ₂ is NO. Yield calculated for two lots, Y ₃ is NO. Yield calculated for 3 lots.

After the yields Y ₁ , Y ₂ and Y ₃ for each lot in the preceding wafer group are obtained as described above, if the next order is received, the optimum wafer number insertion step 71 for the custom process is determined. in orders wafer optimum number Xb following formula with the product number to custom process corresponding based on (3), the yield Y ₁ obtained for each lot,
The yield Yb that matches the optimum value Xb of Y ₂ and Y ₃ is used and calculated. Xb = P / N × Yb (3)

This calculation processing is executed by the second data processing device 56, and at this time, the yields Y ₁ , Y ₂ , Y ₃ for each lot stored in the memory are read out and used as appropriate.

For example, if the optimum number of wafers Xb for the custom process corresponding to the number of ordered products is satisfied by the following equation (4), NO. Wafers of one lot are thrown into the custom process 64. Xb = P / N × Y ₁ (4)

When the optimum number of wafers is calculated in the above manner, as shown in FIG. 1, in the lot unloading step 72, N of the yield Y ₁ used for the above calculation is calculated.
O. One lot is unloaded from the lot group stored in the wafer stocker 53 and put into the custom process 64.

Thereafter, the optimum wafer number determination process 71 and the lot unloading process 72 are repeated each time the next order 70 is received, so that the optimum wafer number Xb to the custom process 64 corresponding to each ordered product number becomes Of the yields Y ₁ , Y ₂ , and Y ₃ obtained for each lot, the yield Yb that matches the optimum value Xb is used for calculation, and the wafer group of the yield lot used for the calculation is customized. The process 64 is sequentially performed.

When all the wafer groups of the lot used for the preceding wafer group are sent to the custom process, or when the number of wafers becomes small, the above-mentioned predetermined order 65, the preceding wafer number determining process 66, and the preceding wafer number determining process 66, The wafer group formation step 67 and the lot yield calculation step 69 for each preceding wafer group are executed. After that, by repeating the above-described steps, the make-to-order manufacturing of the mask ROM wafer is continued.

The mask ROM wafer that has undergone the custom process 64 and the wafer inspection process 68 is sent to the subsequent process 73 in both the preceding wafer group and the succeeding wafer group.

According to the above described embodiment, the following effects can be obtained.

(1) During wafer production in the mask ROM wafer custom process, the yield of each lot of the stored wafer group can be preliminarily confirmed by the preceding wafer group. Can be suppressed, and as a result, the accuracy of the production control method in the mask ROM wafer custom process can be improved.

(2) The mask ROM according to the above (1)
Since the accuracy of the wafer production control method in the wafer custom process can be increased, it is possible to secure the production amount commensurate with the received order amount and enhance the productivity.

(3) Among the mask ROM wafer production processes, the master process can continue the prospective production, so that it is possible to prevent the productivity of the mask ROM wafer from being reduced as a whole.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the specific structure of the wafer production control device, the lot formation device of the preceding wafer group, and the specific configuration of the lot formation method of the preceding wafer group are not limited to those in the above-described embodiment, but are in use conditions and environments. It can be appropriately selected according to the above.

Since the first data processing device and the second data processing device are constructed by a computer or the like, they may be integrally configured, or they may be configured by being incorporated in a host computer or the like which controls production control. Good.

In the above description, the case where the invention made by the present inventor is mainly applied to the production control technique of the mask ROM wafer which is the field of application which is the background of the invention has been described, but the present invention is not limited to this. The present invention can be applied to a semiconductor device wafer, a data storage medium such as a floppy disk, a hard disk, a compact disk and the like, and other production control techniques for all works that can be produced separately in a master process and a custom process.

[0078]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

In the custom process, the preceding number corresponding to the number of orders at any time is determined, and the determined number of works from the stored work group are extracted from each lot for each small number and prepared. When the custom process is completed, the preceding number of workpieces are put into the custom process to produce the product, and after the custom process, the yield is calculated for each lot of the preceding work group in the inspection process.
The optimum number of inputs to the custom process corresponding to the number of orders is calculated by using the yield that matches the optimum value from the yield group obtained for each lot for the preceding work group,
By selecting the lot corresponding to the used yield and inputting the lot to the custom process, each of the yields of the stored lots can be preliminarily set by the preceding work group during production in the custom process. Since it is confirmed, it is possible to suppress the influence of the variation in yield and improve the accuracy of the production control method.

[Brief description of drawings]

FIG. 1 is a process diagram showing a wafer production control method according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a wafer production control apparatus according to an embodiment of the present invention.

FIG. 3 is a schematic view showing a knitting device for a preceding wafer group used therein.

FIG. 4 is a perspective view thereof.

FIG. 5 is a schematic diagram showing a lot formation method for a preceding wafer group.

FIG. 6 is a schematic plan view showing a wafer.

FIG. 7 is a perspective view showing a cassette.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Wafer, 2 ... 1st main surface, 3 ... Orientation flat, 4 ... Identification code, 5 ... Lot code, 6 ... Wafer code, 11 ... Lot formation device of preceding wafer group, 12
... Machine frame, 13 ... First station, 14 ... Second station, 15 ... Third station, 16 ... Fourth station, 17 ... Actual cassette, 18 ... Conveyor, 19 ... Controller, 20 ... Empty cassette, 21 ... Robot, 22 ... Controller, 23 ... Arm, 24 ... Grip, 30 ... First identification code reading device, 31 ... Alignment device,
32 ... Controller, 33 ... Illumination device, 34 ... Light source, 3
5 ... TV camera, 36 ... Identification code recognition device, 37 ...
Monitor, 38 ... memory, 40 ... first data processing device,
50 ... Wafer production control device, 51 ... Wafer identification code assigning device, 52 ... Master process wafer lot organization device,
53 ... Wafer stocker, 54 ... Custom process device, 55 ... Wafer inspection device, 56 ... Second data processing device, M1 ... First actual cassette, M2 ... Second actual cassette, M
3 ... Third actual cassette, A ... Empty cassette, 60 ... Wafer production control method, 61 ... Lot packing process, 62 ... Master process, 63 ... Storage process, 64 ... Custom process, 65 ... Predetermined order, 66 ... Advance Wafer number determination step, 67 ... Lot organization step of preceding wafer group, 68 ... Wafer inspection step, 69
... Lot yield calculation step of preceding wafer group, 70 ... Order receiving, 71 ... Optimal wafer number insertion step, 72 ... Lot unloading step, 73 ... Post step.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Toshiyuki Nakano 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Hitachi, Ltd. Semiconductor Division

Claims (3)

[Claims] 1. A master process in which a large number of works are sequentially organized into a lot of lots and are prospectively produced, and a storage process in which a work group produced in the master process is stored while maintaining the previous lot. And a custom process in which a work group stored in response to an order is input and produced while maintaining a previous lot, the production control method for a production method, wherein the custom process In (1), the preceding number corresponding to the number of orders at any time is determined, and the determined number of works from the stored work group are prepared by picking up from each lot to a small number respectively The preceding number of works is put into the custom process to be produced, and after the custom process, the yield is calculated for each lot of the preceding work group in the inspection process. In the subsequent orders, the optimum number of inputs to the custom process corresponding to the number of orders is obtained by using the yield that matches the optimum value among the yield groups obtained for each lot for the preceding work group. A production control method, wherein a lot corresponding to the used yield is selected and put into a custom process of the lot. 2. In the lot organization in the master process, each work is provided with a unique optically readable unique lot identification code, and when each preceding work group is extracted from each lot in a small number. The lot identification code attached in advance to the work is read, and the read lot identification code is stored, and when the yield is obtained for each lot of the preceding work group in the inspection process after the custom process is finished, The yield for each lot is stored in association with each of the stored lot identification codes, and when a lot in the subsequent orders is selected,
The production control method according to claim 1, wherein the stored lot identification code is used. 3. A master process in which a large number of works are sequentially organized into a large number of lots and are prospectively produced, and a storage process in which a work group produced in the master process is stored in a state in which the previous lot is maintained. And a custom process in which a work group stored in response to an order is input and produced in a state in which a previous lot is maintained, and a custom process, the master process In, in the master process, an identification code assigning device that attaches an optically readable lot identification code to a large number of workpieces, and a lot organization device that organizes the work group into a designated lot by reading the lot identification code In the storage process, a work stocker that stores a work group while maintaining a lot and a work stocker in the custom process. Computer for reading the lot identification code attached to each work stored in each lot and storing it for each lot, and extracting the work from each lot to form a preceding work group, and a computer In the custom process, in the custom process, the preceding number corresponding to the number of orders at any time is determined, and the preceding work group organization device is used to From this lot, the work of the determined number is extracted from each lot for each small number and prepared, and the preceding number of the extracted work is put into the custom process to be produced, and after the custom process, In the inspection process, the inspection device that obtains the yield for each lot for the preceding work group and the computer, etc. The built-in data processing device, and in the subsequent orders, the optimum number of inputs to the custom process corresponding to the number of orders is matched to the optimum value of the yield group obtained for each lot for the preceding work group. And a data processing device for designating a lot corresponding to the used yield and inputting the lot to a custom process.