JPH06104154A - Automatic quality control system - Google Patents

Abstract

PURPOSE:To enable effective function by carrying out control to even a kind if a small injection number by results of a lot of the same type by updating manufacturing conditions of a process which registers a parameter value for deciding quality to be managed and controlled and decides quality based on a difference between quality standard and inspection results, and a parameter. CONSTITUTION:An input 1a of inspection results is loaded with measurement results in an inspection process. In determination 1b of time lag, an operation time in a process for deciding quality and an update time of existing operation conditions are compared; if the operation time is precedent, inspection results thereof are prevented from affecting control. In a calculation 2 of a standard difference, a standard difference between measurement results of electrical characteristic value in an inspection process and a standard value is calculated and a value thereof is delivered to a control 3 of operation conditions. In the control 3 of operation conditions, operation conditions are updated by a parameter value for control and the control difference. Therefore, even if the number of kinds to be controlled is large, the number of manual processes for registering and updating a parameter value can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quality control system including a process of determining quality represented by characteristic values and the like, and a quality inspection process.

[0002]

2. Description of the Related Art A conventional quality control system will be described with reference to the drawings.

FIG. 3 is a block diagram of a conventional system.

The input 19a of the inspection result is a step of taking in the result measured in the inspection process, and the calculation 19 of the standard difference is performed.
In step b, the standard difference between the quality plan and the inspection result is obtained, and the difference is passed to the work condition control 20.

The operation condition control 20 is detailed in Step 2
It is divided into 1 to 24. The update interval determination 21 accumulates the standard difference and the inspection lot number until the inspection lot number reaches the update interval, and proceeds to the next step only when the update interval is reached. The update interval is a constant with only one setting on the control system. The calculation 22 of the average value of the standard difference calculates the average standard difference per lot. The calculation 23 of the change amount of the work condition recalculates the work condition by the following formula.

New work condition = old work condition + (average standard difference per lot × unit change amount) The unit change amount is the update amount of the work condition of one quality standard unit set by the parameter registration 26. Is.
For example, in the case of the electric characteristic value, when the unit of the electric characteristic value is volt (V), it is the amount of change in the working condition necessary to change the electric characteristic value by 1 volt.

The work condition update 24 is to register the work condition in the control data storage 27. The parameter value setting 25 is a parameter value setting means for control. In the parameter value registration 26, the parameter value is registered in the control data storage 27 for each product type of the quality standard.

Since the management unit of the control system is the product type, even if the data of the product of the same quality standard is already registered, it is necessary to register all data for each product type. The types of parameter values are quality standard and unit change amount. The control data storage 27 stores parameter values and control data for control. A work condition search 28 searches the control data storage 27 for the work condition of the product type using the product name as a key. The condition display 29 displays the work condition on the work report terminal.

[0009]

In recent years, a large amount of small quantities and a wide variety of products have been rapidly developed throughout the manufacturing industry, but the number of man-hours for quality control has increased in proportion to the number of products. Also, since quality standards and manufacturing methods differ depending on the product type, there is a limit with the conventional uniform management method.
Functions that flexibly adjust management and control methods and more accurate quality control systems are required.

In a quality control system applied to a production line for a small amount of a large number of products, since a large number of products must be managed, a considerable amount of man-hours is required to register and update the parameter values set for each product. There was a problem to say.

Further, in the case of management by product type, in the case of products with a small number of inputs, there is a problem that the update interval lot number does not reach and the control system does not function effectively.

Further, the number of renewal interval lots must be set so that the loss due to it is minimized. For that purpose, it is necessary to freely change the update interval by human judgment, but there is a problem that the conventional system cannot do so.

[0013] In the measurement result in the inspection process, unexpected nonstandard data due to disturbance or measurement error may occur, but if they are not excluded as noncontrol data,
The amount of change in working conditions is different from the value that should meet the originally predicted quality standard.

However, when the cause of generation of the standard data is unknown on the management system, the determination as to whether or not it is the non-control data is made in consideration of the generation rate of the non-standard data in a normal state. There is a need to.

In other words, if a product with a low occurrence rate of a non-standard lot occurs, it may be excluded as non-control data. Conversely, if it occurs with a product with a high occurrence rate, the quality standard On the other hand, since the process capability is often low, it is necessary to incorporate it into the control as normal data.

However, it is difficult for the system to make those judgments, and there is no choice but to rely on a human system, which requires a great deal of management man-hours.

Further, there are cases in which there is an error due to lot-specific variations in the amount of change in manufacturing conditions set based on the difference between the quality standard obtained in the inspection process and the inspection result. However, since the manufacturing condition is updated while ignoring the error, there is a problem that the characteristic value may hunt.

If there is a work time lag between the quality determining step and the quality inspecting step, the lot operated under the condition of a generation older than the current manufacturing conditions is inspected in the inspecting step, and Since the data is directly reflected as the control data, there is a problem that the correct control cannot be performed.

[0019]

A feature of the present invention is that when a product is manufactured and provided with a process of determining quality represented by a characteristic value and a process of inspecting quality, Set a unique control number for each quality standard and register it for each product type, and a parameter value that determines the quality to be managed / controlled using the management number as a key for management. Based on the difference between the standard and the inspection result obtained from the inspection process and the parameter value, means for updating the manufacturing conditions of the process for determining the quality,
In the means for updating the manufacturing conditions described above, means for determining whether or not the inspection result in the inspection process is a result that should be excluded due to control that suddenly occurred, and a criterion for the determination is set by a human as a parameter value. Variable means, means for setting the update interval of manufacturing conditions in the process of determining quality according to the number of inspection lots in the inspection process, means for setting / changing the update interval by a person as a parameter value, and control If there is an error in the predicted value of the quality standard, means for setting a discount coefficient to prevent hunting in the inspection result, means for varying the amount of change in manufacturing conditions by the discount coefficient, and in the inspection process There is provided means for determining a lot having a time lag between the work time of the process for determining the quality and the update time of the manufacturing condition and eliminating the result.

[0020]

The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, showing a feedback type quality control system for controlling electrical characteristic values in a semiconductor device production line.

In a production line, a lot is processed in a quality determining process and then passes a quality inspection process, but there may be two other processes. Therefore, lots processed under the old work conditions may arrive in the inspection process, or lots may arrive in an order different from the processing order of the quality determining process. Further, the result of the inspection process includes an error due to disturbance.

Therefore, in FIG. 1, the input 1a of the inspection result is a step of fetching the result measured in the inspection process. In the time lag determination 1b, the work time of the process for determining the quality is compared with the update time of the current work condition, and if the work time is older, the inspection result is not reflected in the control. In the standard difference calculation 2, the standard difference between the measurement result of the electrical characteristic value in the inspection process and the standard value is calculated, and the calculated value is passed to the work condition control 3. The work condition control 3 is to update the work condition based on the parameter value for control and the standard difference, and includes steps 4 to 10. Judgment 4 of the update interval counts the number of lots worked in the inspection process, and if it is smaller than the update interval, simply integrates the number of standard lots and their standard difference and the number of non-standard lots and their standard difference, Do not activate the subsequent processing steps. The update interval is a parameter value that can be freely set for each quality standard unit, and is registered by the parameter value registration 12. Exception data judgment / removal 5
This is a process that relies on human judgment in the prior art, and in this control system, the judgment standard for exceptional lots is incorporated into the control system in the form of a permissible rate for nonstandard lots for automation. As the processing, if the ratio of the number of non-standard lots to the total number of inspected lots is less than the allowable ratio of non-standard lots set as a parameter value, the standard difference of non-standard lots is not reflected in the control. Is. In the calculation 6 of the average value of the standard difference, the average standard difference per lot is calculated. The calculation formula is shown below.

(1) When the non-standard lot is reflected in the control, the following first expression is used.

[0024]

(2) When the non-standard lot is not reflected in the control, the following second formula is obtained.

[0026]

In the calculation 7 of the working condition change amount, the working condition change amount is calculated by multiplying the average standard difference per lot by the unit change amount set as a parameter value. In the reflection 8 of the discount coefficient, the change amount of the work condition is multiplied by the value of the discount coefficient set as the parameter value to discount the change amount. This is to minimize the loss of quality defects due to the error included in the standard difference, and is based on the theory of online quality control advocated by Mr. Hajime Taguchi (Reference: Genichi Taguchi, online in the manufacturing department). Quality control issued by Japanese Standards Association.

In the update 9 of the working condition, the change amount is added to the current working condition and the result is stored in the control data memory 13 as the latest working condition.

From the above, the latest working condition calculation formula is as the following third formula.

[0030]

The update date setting 10 is such that the update time of the manufacturing condition is stored in the control data 1 for the determination of the time lag lot.
It is stored in 3. Input the parameter value 11
It is a means for inputting parameter values for control. In the parameter value registration 12, the parameter value is registered using the management number as a key. The management number is a management number set corresponding to the type of quality standard. The types of parameters include quality standard, unit change amount, update interval, non-standard lot tolerance rate, and discount coefficient. The control data storage 13 stores control data used in the control 3 of parameter values and work conditions, using the management number as a key. The management number registration 14 registers the management number corresponding to the quality standard of the product type with the product type name as a key. In the case where this management system is applied to a new product type, if the registered product types have the same quality standard, this process only needs to be performed. The management number storage 15 stores a management number for each product type. Work condition search 16
This is a search for the work conditions of the work lot in the process of determining the quality. The management number storage 15 is searched using the lot type name as a key, and the management number of the type is searched. Then, the control number memory 13 is searched with the management number as a key to obtain the value of the working condition. In the work time storage 17, the work time of the process for determining the quality is stored as the judgment data of the time lag judgment 1. In the work condition display 18, the work condition is displayed on the work report terminal.

FIG. 2 shows the configuration of the computer of the embodiment.

In the process of determining the quality, when the work report terminal 30 issues a start report at the start of work, the work conditions are displayed. In the inspection process, the inspection result is input from the operation report terminal 30 at the time of the operation report and is stored in the host computer 32 through the data transmission path 33.
In addition, the parameter value for control is the data setting terminal 3
1 is input and stored in the boot computer 32. The host computer 32 automatically performs the work condition control 3 shown in FIG. 1 based on the data.

[0034]

As described above, the present invention has the following effects.

(1) Even if the number of products to be managed is large,
It is possible to reduce man-hours required to register and update parameter values.

(2) Since it is managed and controlled in units of quality standards, even for products with a small number of inputs, control is performed based on the results of lots of other products of the same quality standard, which is effective as a management system. Function.

(3) Since the update interval can be freely set by human judgment, it is possible to perform management such that the loss is always minimized.

(4) Of the measurement results in the inspection process,
Non-standard data that suddenly occurs such as disturbances and measurement errors,
Since the human judgment standard can be reflected in the system, it can be eliminated on the system side, thereby improving the control accuracy and reducing human management man-hours.

(5) When there is an error in the predicted value of the product type standard in control, the pulling coefficient for discounting the error can be reflected in the control, so that the possibility of hunting of the inspection result is reduced. be able to.

(6) If there is a work time lag between the quality determining process and the quality inspection process, the data of lots operated under the generation conditions older than the current manufacturing conditions are excluded. , The control accuracy becomes higher.

Therefore, it is possible to reduce the manufacturing cost and to produce a higher quality product.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of a computer according to an embodiment.

FIG. 3 is a block diagram of a conventional technique.

[Explanation of symbols]

 1a Input of inspection result 1b Judgment of time lag 2 Calculation of standard difference 3 Control of working condition 4 Judgment of update interval 5 Judgment / elimination of exceptional data 6 Calculation of average value of standard difference 7 Calculation of amount of change in working condition 8 Discount coefficient 9 Update of working conditions 10 Setting of update date 11 Input of parameter value 12 Registration of parameter value 13 Control data storage 14 Registration of management number 15 Storage of management number 16 Search of working condition 17 Storage of working time 18 Display of condition 19a Input of inspection result 19b Calculation of standard difference 20 Control of working condition 21 Judgment of update interval 22 Calculation of average value of standard difference 23 Calculation of change amount of working condition 24 Update of working condition 25 Input of parameter value 26 Parameter value Registration 27 Storage of control data 28 Search for work conditions 29 Display of conditions 30 Work report terminal 31 Data setting terminal 2 host Konpyuta 33 data transmission path

Claims (3)

[Claims] 1. In a product manufacturing process including a process of determining quality represented by a characteristic value and the like, and a quality inspection process, when quality is managed and controlled, management specific to the product quality standard is performed. It has a means for setting a number and registering it for each product type, and a means for registering a parameter value that determines the quality to be managed / controlled using the management number as a management key. An automatic quality control system, characterized in that the manufacturing condition of the step of determining quality is updated based on the difference between the obtained inspection result and the parameter value. 2. The means for updating the manufacturing conditions, wherein the means for determining whether or not the inspection result in the inspection step is a result that should be excluded due to control that suddenly occurs, and a criterion for the determination is a parameter. A means that can be set and changed as a value, a means that sets the update interval of the manufacturing conditions of the process that determines quality depending on the number of inspection lots in the inspection process, and a means that can set and change the update interval as a parameter value. If there is an error in the predicted value of the above quality standard, it has means to set a discount coefficient to prevent hunting in the inspection result, and the amount of change in manufacturing conditions can be changed by the discount coefficient. The automatic quality control system according to claim 1, wherein: 3. The method according to claim 1 or 2, wherein a lot having a time lag between a work time of a process for determining quality in an inspection process and a manufacturing condition update time is judged and the result is excluded. Automatic quality control system.