JP4768935B2 - Production management device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a production management method and apparatus for determining a processing order of a plurality of lots in a production line that performs a series of processes consisting of a plurality of processes for each of a plurality of lots.
[0002]
[Prior art]
Various production of products by putting raw materials in lot units into a production line with multiple facilities including facilities that perform multiple types of processes and performing various processes according to a series of process flow (process flow) Used in various industries. For example, in a semiconductor factory, a semiconductor substrate (wafer) is put into a production line in units of lots (for example, 25), and processing in a process using any one of the plurality of facilities is repeated. A manufacturing process is employed in which a structure necessary for a semiconductor integrated circuit is sequentially formed on a semiconductor substrate.
[0003]
In this semiconductor integrated circuit production, a plurality of lots in various processing steps are generally present in the production line. In addition, the same equipment may be used in a plurality of processes, and from these facts, a plurality of lots may wait for processing and stay in one equipment.
[0004]
In such a case, conventionally, as an index for determining the priority order for processing the stayed lot with the one facility, the delivery date required for the lot and the expected lot at that time The difference from the scheduled finish time (time allowance) is used.
[0005]
[Problems to be solved by the invention]
However, since the above index is an index that is conscious only of the delivery date, variations in TAT (Turn-Around-Time; time from when a lot is put into the production line to passing through the finishing process) are not considered at all. Therefore, realizing a stable TAT is not a problem. In addition, with such an index, in-process lots that have margins for delivery are likely to stay more than necessary, and uneven distribution of the lots is likely to occur. When the uneven distribution of lots occurs, the load balance between the facilities maintained at the time of introduction may be lost, and the operation rate of the entire production line may be reduced. Furthermore, if a specific lot is left unnecessarily for a long time even if there is an allowance in the delivery time, the surface state may deteriorate, for example, organic substances may adhere to the surface of the semiconductor substrate, which is not preferable in terms of quality.
[0006]
The present invention aims to consideration of the above situation, without delaying the delivery date, to suppress the accumulation of unnecessarily also lots of delivery room, to provide a production tubing MakotoSo location where it is possible to reduce variations of TAT And
[0007]
[Means for Solving the Problems]
The production management apparatus of the present invention that achieves the above object is a production management apparatus that manages processing from the input of a plurality of lots to the finishing in a production line having a plurality of facilities including facilities for performing a plurality of types of processes. Because
The processing order of at least two lots that have reached the process of using a specific facility in the production line in the plurality of lots is the difference between the delivery date of each lot and the current scheduled finish time. It is characterized by having a processing order determining unit that determines both the slack and the slack2 that is the difference between the scheduled finishing time at the time of input and the scheduled finishing time at the present time.
[0008]
According to the production management apparatus of the present invention, in addition to the above-mentioned “sack”, “sack2”, which is the difference between the scheduled finishing time at the time of input and the scheduled finishing time when the processing order is determined by this method, is also used as an index. It is possible to suppress the stagnation more than necessary for a certain lot. Further, here, “slack” and “slack2” are considered not as absolute values of differences but as values having a positive / negative concept. TAT variation can be reduced.
[0009]
In the production management apparatus of the present invention , it is preferable that the processing order of the at least two lots is determined in preference to the order in which the slack2 is small for the lot whose slack exceeds the threshold.
[0010]
Furthermore, in the production management apparatus of the present invention , the processing order of the at least two lots is as follows: first, the lots whose slack is less than or equal to the threshold value, in order of increasing the slack; It is preferable that this is a mode in which priority is determined in ascending order.
[0011]
In addition, in the production management apparatus of the present invention , it is also one of preferred aspects that the processing order of the at least two lots is determined in preference to the smaller one of the slack and the slack2 in ascending order.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
First, an embodiment relating to a production management apparatus of the present invention will be described.
[0014]
The production management apparatus of this embodiment is used when determining the processing order of a plurality of lots in a series of wafer processing steps in which a necessary structure as a semiconductor integrated circuit is sequentially formed on a semiconductor substrate.
[0015]
FIG. 1 is a process flow diagram showing a flow from the start to the end of a series of wafer processing steps.
[0016]
Since this series of wafer processing steps is well known, description of each step is omitted, but each step from oxidation to impurity diffusion and metal steps are repeated. The process from oxidation to impurity diffusion is called a front process, and the aluminum electrode formation performed thereafter is called a metal process. In this wafer processing step, facilities such as a furnace, an exposure machine, and an etcher are used in a plurality of steps.
[0017]
Next, characteristic functions of the production management apparatus of this embodiment will be described with reference to FIG.
[0018]
The production management apparatus 30 of the present invention is realized as a part of the production management system 10 that manages the entire production line, for example. That is, a program for realizing the functions of the production management apparatus of the present invention is stored together with a program for realizing various other functions on the hard disk of the host computer constituting the production management system. Then, by reading the program into the main memory, the CPU of the host computer exhibits the function as the production management system of the present invention.
[0019]
The production management device 30 of the present invention is functionally divided into an input unit 31, a processing order determination unit 32, and an output unit 33, as shown in FIG. The input unit 31 includes a lot management database 11 that stores data related to a plurality of lots managed by the production management system, the input date of each lot, standard TAT, delivery date, current position (next processing step at the present time), Get the data.
[0020]
The processing order determination unit 32 uses the data acquired by the input unit 31 to calculate values such as “sack” and “sack2”, which will be described later, and uses these values as indices to determine the processing order of a plurality of in-process lots. To do.
[0021]
The output unit 33 outputs the processing order determined by the processing order determination unit 32 to the processing order registration unit 12 of the production management system. And a processing order registration part registers the processing order of each equipment, and each equipment processes a lot according to the registered processing order.
[0022]
Next, FIG. 3 shows the production line management performed using the production management system 10, in particular, the process of determining the lot processing order in the series of wafer processing steps shown in FIG. 1 performed using the production management device 30. It explains using. Reference is also made to FIG. 4 as necessary.
[0023]
FIG. 3 is a flowchart showing a production management processing routine from when a sales order of a certain lot is reported until the processing of the lot in the series of wafer processing steps shown in FIG. 1 is completed. FIG. 4 is a diagram for explaining the concepts of “sack” and “sack 2” calculated by the processing order determination unit included in the production management apparatus 30 of the present embodiment.
[0024]
First, when a sales order based on the contents of an order is communicated, the person in charge determines from the contents of the sales order whether the current sales order is within the processing capacity of the production line (see FIG. 3). Step S1), if it does not fit, adjust the delivery date of the business or the delivery date of other lots that have already been input. On the other hand, if it falls within the processing capacity of the production line, the production management system is instructed to input a lot based on the sales order to the production line (step S2 in FIG. 3). At this time, data such as the input date and delivery date of the lot are input to the production management system and stored in the lot management database 11 together with the standard TAT calculated in the production management system. Subsequently, the lot is input to the production line based on an instruction given to the input process by the production management system (step S3 in FIG. 3).
[0025]
Here, the input unit 31 shown in FIG. 2 displays the input date (Di), the standard TAT (Ts) of the lot expected from the past results, and the delivery date (Dd) of the lot shown in FIG. get. The horizontal axis of the graph shown in FIG. 4 represents time (date). Also, the vertical axis of the graph shown in FIG. 4 shows the flow of the series of wafer processing steps shown in FIG. 1, and approaches the final (finished) step as it goes downward, and the lowest end indicates that the processing by the finishing step is completed. To express. The processing order determination unit 32 obtains the scheduled finishing date (Ds) at the time of loading shown in FIG. 4 from the loading date (Di) and standard TAT (Ts) based on the following formula (1).
Ds = Di + Ts (1)
Then, the processing order determination unit 32 calculates both the sack value and the sack2 value in step S4 of FIG. In step S4, first, the input unit 31 acquires a current position X (see FIG. 4) indicating which process in the wafer processing process the lot is currently in. Then, from the current position X, a standard progress line as shown in FIG. 4 (a line having the same inclination as the line connecting the position (St) at the time of input and the scheduled finish date (Ds) at the time of input) is drawn. Then, the scheduled finish date (Dx) at the present time shown in FIG. 4 is calculated. Then, “sack” is obtained from the following equation (2), and “sack2” is obtained from equation (3).
slack = Dd−Dx (2)
slack2 = Ds−Dx (3)
The “sack” calculated by the equation (2) is the time difference between the delivery date (Dd) and the current scheduled finish date (Dx), and how much time is available for the current scheduled finish relative to the delivery date. It represents. In other words, the finishing schedule at the present time is delayed with respect to the delivery date when the slack is a negative value, and there is a margin with respect to the delivery date when the slack is a positive value. In the graph shown in FIG. 4, the finish schedule at the present time has a margin with respect to the delivery date. Also, “slack2” calculated by the equation (3) is a time difference between the scheduled finish date (Ds) at the time of introduction and the scheduled finish date (Dx) at the present time. It shows how much time you can afford for the schedule. That is, the finish schedule at the present time is delayed with respect to the finish schedule at the time of introduction if slack2 is a negative value, and there is room for the finish schedule at the time of introduction if positive. In the graph shown in FIG. 4, the finish schedule at the present time is delayed from the finish schedule at the time of input.
[0026]
In the series of wafer processing steps shown in FIG. 1, for each of the processes in which lots tend to stay, the slack and the slack 2 of a plurality of lots reaching the processing process are calculated. Then, the processing order determination unit 32 determines the priority for processing the plurality of lots in consideration of both of the “sack” and “sack 2” (step S5 in FIG. 3). Although there are various modes for determining the priority, some examples to which the embodiment of the production management method of the present invention is applied will be described with reference to FIG.
[0027]
FIG. 5 is a diagram illustrating an example in which priorities are determined by each of a plurality of methods of determining priorities in a certain process.
[0028]
FIG. 5 shows two diagrams (a) and (b). In each diagram, the upper diagram shows an example in which the priority order is determined using “slack” and “slack2” as indices. In these upper figures, one lot is shown for each horizontal row, and from the left, the priority order, the lot number, the value of “slack”, the value of “slack 2”, and the recipe ID are shown. Here, each process has various processing conditions, and the recipe ID is a code assigned to each processing condition in the process of determining the priority. In each figure, the lower figure shows the priority order obtained by reorganizing the priority order shown in the upper figure with the same recipe ID.
[0029]
In the upper diagram of FIG. 5A, a threshold value of “0” is provided for the value of the stack, and the processing order is determined by giving priority to the lot having the value of 0 or less than the lot having the value of the stack larger than 0. An example is shown. In this example, the priority is determined in the order of increasing the value of the slack for the lots with a slack value of 0 or less, and the priority is determined in the order of the values of the slack 2 for the lots with a larger value of the slack. Yes. In other words, the lots with the first to fourth priorities are lots having a value of “sack” of 0 or less (the finished schedule has no room for the product delivery date), and these four lots (lot number A06, In A07, A04, A05), the priority order is determined in ascending order of the value of the slot. In addition, each of the eight lots with the priority order of 5th or lower is a lot having a value of “sack” larger than 0 (the current finishing schedule has a margin for the product delivery date), and these 8 lots (lot number A08, A09, A12, A01, A11, A10, A03, A02) are prioritized in ascending order of the value of slot2. Here, among the lots having a value of “slack” greater than 0, those having the same value of “slack2”, such as the three lots of lot numbers A11, A10, and A03, have a higher priority. In addition, in the lots having a slack value of 0 or less, those having the same slack value are given priority to the smaller slack2 value. In this way, a predetermined threshold is provided for the value of the slack, and the delivery date can be prioritized by determining the priority order of the lots below the threshold by using the slack as an index. In addition, the residence time of lots exceeding the threshold can be shortened by determining the priority order using “slack2” as an index. Note that it is preferable that the most suitable value is adopted as the threshold of the value of the slack for each process. For example, in a process with a long processing time using a diffusion furnace or the like, if a processing opportunity is missed, a long processing time is likely to be waited. As a result, a delay in delivery is likely to be long. On the other hand, in a process with a short processing time (fast rotation) or a process with a limited time, the residence time is shortened as much as possible by reducing the threshold value.
[0030]
Further, in the lower diagram of FIG. 5A, the order of the lower lots having the same recipe ID as the recipe ID of the upper lot in the priority order shown in the upper diagram of FIG. An example in which the lot is moved to the next lot is shown. That is, a lot having the same recipe ID as the recipe ID “R4” of the lot number A06 having the first priority in the order of priority shown in the upper diagram of FIG. 5A is shown in the upper diagram of FIG. In the example shown in the lower diagram of FIG. 5A, the lot number A12 of the lot number A12 is placed next to the lot of the lot number A06 (second priority). Lots are advanced. And by processing these two lots simultaneously, the batch filling rate is increased to increase productivity. In this example, since the recipe IDs of the second and third priority lots (lot numbers A07 and A04) shown in the upper diagram of FIG. It is considered as it is. In addition to these, there are two lots (lot numbers A01, A11) of the priority ranks 8th and 9th shown in the upper diagram of FIG. 5A. . However, the number of lots that can be processed at one time in each process is limited to two. For this reason, the order of the 8th and 9th priority orders (lot numbers A01 and A11) is not increased and remains in this order. I have to. For the same reason, the lowest order lot (lot number A02) of the lot whose recipe ID is “R2” and the lowest order lot (lot number A03) of the lot whose recipe ID is “R3”. The priority has not been raised.
[0031]
In the upper part of FIG. 5B, the reference value of a plurality of lots is compared using the smaller one of “slack” and “slack2” as a reference value, and the priority order is determined in ascending order of the reference value. An example is shown. That is, the reference value for each lot is “−3” for the lot number A06, “−3” for A08, “−2” for A07, “−2” for both A04 and A09, and “−1” for A12. A01 is “−1”, A05 is “0”, A11, A10, and A03 are all “0”, and A02 is “2”. Here, in this example, when the reference value is the same value, first, it is determined whether the reference value is a value of “sack” or “sack 2”, and the reference value of the value of “sack” is set higher. Next, when the reference value is the same as the value of “slack”, or the same value is the value of “sack2” as the reference value, the other not used as the reference value (the value of “slack” is the reference value). Are compared with each other, and the lot with the smaller value is given priority. That is, the reference value of each of the three lots of the lot number A07 lot, the lot number A04 lot, and the lot number A09 lot is “−2”. Of these, only the lot number A07 lot is included. Since the value of “sack” is set as the reference value, the lot of the lot number A07 is the higher rank among the three lots. The other of the lot number A04 that is not set as the reference value (slack2 value) is "-1", and the other lot of the lot number A09 that is not set as the reference value (slack2 value) is "6". Therefore, the lot of lot number A04 is in the middle of the three lots, and the lot of lot number A09 is in the lower of the three lots.
[0032]
Further, in the lower diagram of FIG. 5B, as in the lower diagram of FIG. 5A, the recipe ID of the upper lot in the priority order shown in the upper diagram of FIG. An example is shown in which the order of the lower lot of the same recipe ID is moved next to the higher lot.
[0033]
Then, the priority order determined in this way is output to the processing order registration unit, and the processing order of the equipment for which the processing order is to be determined is registered (step S6 in FIG. 3). In the example shown in FIG. 3, the processing from step S4 to step S6 is executed once a day until the processing in the finishing process is completed after the lot is inserted. When the processing in the series of wafer processing steps shown in FIG. 1 is finished, the production management processing routine shown in FIG. 3 is finished.
[0034]
By executing the production management processing routine as described above, the lot can be produced by a predetermined delivery date. Also, lots tend to stay, so-called high-load processes that may require processing that exceeds the processing capacity, processes that require frequent maintenance, processes that require a long time for maintenance, etc. Therefore, it is possible to prevent a lot having a sufficient margin for delivery time from staying more than necessary, and to keep the load balance of the production line close to that at the time of lot introduction. Furthermore, variations in TAT can be reduced.
[0035]
Here, with respect to the average TAT expected from the past results, the variation in TAT when using the method of determining the priority using only the value of the stack as an index, and one of the production management methods of the present invention. A comparison will be made between TAT variations when the method of determining the priority using both the values of slack and slack2 as an index is used as an embodiment. Here, the method of determining the priority order using both the values of slack and slack2 as an index is the method of determining the priority order using the reference value described with reference to the upper diagram of FIG. is there.
[0036]
First, the average TAT of the front process shown in FIG. 1 calculated from past results is 23.10 days. When the variation in TAT is expressed using standard deviation, it is 2.64 days when the method of determining priority using only the value of slack as an index, whereas both slack and slack2 When the method of determining the priority order using the value as an index is used, it is 2.31 days. In addition, when the variation in TAT is expressed using 3 sigma, it is 7.92 days when the priority determination method using only the value of the slack is used as an index, whereas both the slack and the slack2 When the method of determining the priority order using the value as an index is used, it is 6.93 days, and the embodiment of the present invention shows an improvement of 0.99 days.
[0037]
Next, the average TAT of the metal process shown in FIG. 1 calculated from the past results is 15.00 days. And, when the variation of TAT is expressed using standard deviation, it is 3.84 days when the method of determining the priority order using only the value of slack as an index, whereas both slack and slack2 It is 3.42 days when the method of determining the priority order using the value as an index is used. In addition, when the variation in TAT is expressed using 3 sigma, it is 11.52 days when the method of determining the priority using only the value of the slack as an index, whereas both the slack and the slack2 When the method of determining the priority order using the value as an index is used, it is 10.26 days, and the embodiment of the present invention shows an improvement of 1.26 days.
[0038]
Focusing on the result of expressing the TAT variation using 3 sigma, the variation in the front process (maximum value−minimum value) shown in FIG. 1 is shortened by 1.98 days, and the variation in the metal process shown in FIG. (Maximum value-minimum value) is shortened by 2.52 days. Accordingly, in the whole series of wafer processing steps shown in FIG. 1, the range of TAT variation is as small as 4.5 days.
[0039]
In the above example, “sack” and “sack 2” are calculated in units of days. However, other calculation units may be selected depending on the type of line to be managed.
[0040]
The production management method of the present invention can also be applied to a production line for producing a single product type produced in one process flow. However, since indices that can be calculated in common for products produced in different process flows, such as “sack” and “sack 2”, can be suitably applied to a line that produces products of various varieties manufactured in various process flows.
[0041]
The determination of the lot processing order by the production management method of the present invention can be used in combination with other methods. For example, a lot whose delivery date is difficult to achieve can be designated as an express lot, and can be processed with higher priority than priority determination using the “sack” and “sack 2” of the present invention.
[0042]
The production management method of the present invention is applicable not only to the case where the number of semiconductor substrates constituting a lot is a fixed number of, for example, 25, but also to a production line that allows variation. With the recent increase in the size of semiconductor substrates, the number of lots that are less than 25 is increasing. In an extreme case, a production line that allows a lot to be configured with only one semiconductor substrate has also been proposed. Even in such a case, the production management method of the present invention is applicable.
[0043]
【The invention's effect】
As described above, according to the production management method and apparatus of the present invention, it is possible to suppress unnecessarily stagnation and reduce TAT variation without delaying the delivery date even for a lot with a delivery date margin. By suppressing the stagnation, the production line capacity can be used effectively and the production capacity can be increased. Moreover, the accuracy of capability determination in step S1 of FIG. 3 can be increased by reducing variations in TAT.
[Brief description of the drawings]
FIG. 1 is a process flow diagram showing a flow from the start to the end of a series of wafer processing steps.
FIG. 2 is a functional block diagram of the production management apparatus of the present invention.
FIG. 3 is a flowchart showing a production management processing routine from when a sales order of a certain lot is communicated until processing of the lot in the series of wafer processing steps shown in FIG. 1 ends.
FIG. 4 is a diagram for explaining concepts of “sack” and “sack 2” calculated by a processing order determination unit included in the production management apparatus according to the present embodiment.
FIG. 5 is a diagram illustrating an example in which priorities are determined by each of a plurality of methods of determining priorities in a certain process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Production management system 11 Rod management database 12 Processing order registration part 30 Production management apparatus 31 Input part 32 Processing order determination part 33 Output part

Claims (4)

A production management device that manages processing from the introduction of a plurality of lots to the finish in a production line having a plurality of facilities including facilities for performing a plurality of types of processes,
Among the plurality of lots, the processing order of at least two lots that have reached the process of using a specific facility in the production line is the difference between the delivery date of each lot and the current scheduled finish time. A production management apparatus, comprising: a processing order determination unit that determines a slack in consideration of both a slack and a slack2 that is a difference between a planned finishing time at the time of charging and a current scheduled finishing time . The processing order determining unit, the processing order of the at least two lots, the lot where the slack exceeds the threshold value, according to claim 1, characterized in that the determined order; the slack2 small Production management equipment . The processing order determination unit determines the processing order of the at least two lots in the order that the slot is smaller in the order that the slack is less than or equal to the threshold, and then in the order that the slot 2 is smaller in the lot that exceeds the threshold. 2. The production management apparatus according to claim 1, wherein the production management apparatus is determined with priority. The production management apparatus according to claim 1, wherein the processing order determination unit preferentially determines the processing order of the at least two lots in ascending order of the smaller one of the slack and the slack2.

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