Process control method and process control system for manufacturing semiconductor device
Provided are process control methods and process control systems. The method includes performing a deposition process on a lot defined by a group of a plurality of wafers, performing a measurement process on the lot to obtain a measured value with respect to at least one wafer among the plurality of wafers, producing a target value of a factor of a process condition in the deposition process by using a difference between the measured value and a reference value, and providing an input value of the factor with respect to a subsequent lot based on the target value. The operation of providing the input value of the factor includes obtaining a previous target value of the factor previously produced with respect to at least one previous lot, and providing a weighted average of the previous target value and the target value as the input value.
1. A process control method for manufacturing a semiconductor device, the process control method comprising:
performing a first deposition process on a lot comprising a plurality of wafers;
performing a measurement process on the lot to obtain a measured value with respect to at least one wafer among the plurality of wafers;
producing a target value of a factor of a process condition in the first deposition process by using a difference between the measured value and a reference value; and
providing an input value of the factor with respect to a second deposition process for a subsequent lot based on the target value,
wherein providing the input value of the factor comprises:
obtaining a previous target value of the factor, the previous target value being previously produced with respect to at least one previous lot; and
providing a weighted average of the previous target value and the target value as the input value.
2. The process control method of claim 1 , wherein producing the target value of the factor comprises:
obtaining an output value of the factor from the process condition in the first deposition process performed on the lot; and
correcting the output value based on the difference between the measured value and the reference value.
3. The process control method of claim 1 , wherein performing the first deposition process comprises forming a magnetic tunnel junction layer on each of the plurality of wafers,
wherein the measured value comprises electrical or magnetic characteristics of the magnetic tunnel junction layer formed on the at least one wafer among the plurality of wafers,
wherein the reference value is a desired value with respect to the electrical or magnetic characteristics of the magnetic tunnel junction layer.
4. The process control method of claim 3 , wherein
the first deposition process comprises a sputtering deposition process, and
the factor of the process condition comprises one of a pre-sputtering time, a deposition time, an ion incident angle, an ion energy, or an ion current.
5. The process control method of claim 3 , wherein
the magnetic tunnel junction layer comprises a tunnel barrier layer and magnetic layers separated from each other by the tunnel barrier layer,
the first deposition process comprises a sub-deposition process that forms the tunnel barrier layer on each of the plurality of wafers, the sub-deposition process comprising a sputtering deposition process,
the measured value and the reference value comprise resistance (RA) of the magnetic tunnel junction layer, and
the factor of the process condition comprises a pre-sputtering time of the sub-deposition process.
6. The process control method of claim 5 , wherein producing the target value of the factor comprises:
obtaining an output value of the pre-sputtering time from a process condition in the sub-deposition process performed on the lot; and
correcting the output value based on the difference between the measured value and the reference value to produce the target value of the pre-sputtering time.
7. The process control method of claim 6 , wherein correcting the output value to produce the target value of the pre-sputtering time is based on:
Tc=To +( Rf−Rm )/Δ R,
wherein, To represents the output value of the pre-sputtering time, Rf represents the reference value, Rm represents the measured value, ΔR represents a variation of resistance of the magnetic tunnel junction layer per unit of the pre-sputtering time, and Tc represents the target value of the pre-sputtering time.
8. A process control method for manufacturing a semiconductor device, the process control method comprising:
performing a first deposition process on a lot comprising a plurality of wafers to form a magnetic tunnel junction layer on each of the plurality of wafers;
performing a measurement process on the lot to obtain a measured value with respect to characteristics of the magnetic tunnel junction layer formed on at least one wafer among the plurality of wafers;
producing a target value of a factor of a process condition in the first deposition process by using a difference between the measured value and a reference value with respect to the characteristics of the magnetic tunnel junction layer;
providing an input value of the factor based on the target value to change the process condition; and
performing a second deposition process on a subsequent lot based on the process condition that was changed.
9. The process control method of claim 8 , wherein producing the target value of the factor comprises:
obtaining an output value of the factor from the process condition in the first deposition process performed on the lot; and
correcting the output value based on the difference between the measured value and the reference value.
10. The process control method of claim 9 , wherein providing the input value to change the process condition comprises providing the target value as the input value, and wherein the process condition is not changed based on measurements performed on a sample wafer that is distinct from the plurality of wafers.
11. The process control method of claim 9 , wherein providing the input value to change the process condition comprises:
obtaining a previous target value of the factor, the previous target value being previously produced with respect to at least one previous lot; and
providing a weighted average of the previous target value and the target value as the input value.
12. The process control method of claim 8 , wherein
the first deposition process comprises a sputtering deposition process, and
the factor of the process condition comprises one of a pre-sputtering time, a deposition time, an ion incident angle, an ion energy, or an ion current.
13. The process control method of claim 12 , wherein producing the target value of the factor comprises:
obtaining an output value of the factor from the process condition in the first deposition process performed on the lot; and
correcting the output value based on the difference between the measured value and the reference value,
wherein correcting the output value is based on:
Tc=To +( Rf−Rm )/Δ R,
wherein, To represents the output value of the factor, Rf represents the reference value, Rm represents the measured value, ΔR represents a variation of the characteristics of the magnetic tunnel junction layer per unit time of the factor, and Tc represents the target value of the factor.
14. The process control method of claim 8 , wherein the measured value and the reference value correspond to the characteristics comprising one of resistance (RA), magnetoresistance ratio (TMR), exchange magnetic field (Hex), or perpendicular magnetic anisotropy (PMA) of the magnetic tunnel junction layer, and wherein the characteristics of the magnetic tunnel junction layer formed on the at least one wafer of the lot and of a magnetic tunnel junction layer formed on at least one wafer of the subsequent lot are uniform.