CN111427242A - Line width control method applied to advanced control system - Google Patents

Line width control method applied to advanced control system Download PDF

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Publication number
CN111427242A
CN111427242A CN202010425461.9A CN202010425461A CN111427242A CN 111427242 A CN111427242 A CN 111427242A CN 202010425461 A CN202010425461 A CN 202010425461A CN 111427242 A CN111427242 A CN 111427242A
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exposure
exposure energy
energy
line width
coefficient
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CN202010425461.9A
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许博闻
李琛
时雪龙
燕燕
李立人
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Shanghai IC R&D Center Co Ltd
Shanghai IC Equipment Material Industry Innovation Center Co Ltd
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Shanghai IC R&D Center Co Ltd
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/7055—Exposure light control in all parts of the microlithographic apparatus, e.g. pulse length control or light interruption
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/027—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34
    • H01L21/0271—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers
    • H01L21/0273—Making masks on semiconductor bodies for further photolithographic processing not provided for in group H01L21/18 or H01L21/34 comprising organic layers characterised by the treatment of photoresist layers
    • H01L21/0274—Photolithographic processes

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Manufacturing & Machinery (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)

Abstract

The invention discloses a line width control method applied to an advanced control system, which comprises the following steps: setting the original exposure energy E of the 1 st exposureexp(1) And carrying out exposure; after the 1 st exposure is completed, the actual exposure energy E of the 1 st exposure is calculatedl(1) And predicting exposure energy Ep(1) And E isp(1) E (1)/f (1); repeating the steps S01-S02, setting the original exposure energy E of the x-th exposureexp(x) Predicted exposure energy E equal to the x-1 th exposurep(x-1), and performing exposure, and calculating the actual exposure energy E of the x-th exposurel(x) And predicting exposure energy Ep(x) Until the whole exposure process is completed, wherein E (x) represents the initial predicted exposure energy calculated by using an averaging method, f (x) is a monotonically increasing adjustment formula, f (x) ∈ (0,1), and f (x) approaches to 1 along with the increase of xAnd the deviation of the initial period in the process is controlled, so that better exposure energy prediction is obtained in the early period, and the exposed wafer can reach the line width standard more quickly.

Description

Line width control method applied to advanced control system
Technical Field
The invention relates to the field of semiconductor production and manufacturing, in particular to a line width control method applied to an advanced control system.
Background
In a semiconductor Manufacturing System, an Advanced Process Control (APC) System cooperates with an Equipment Automation (EAP) System and a Manufacturing Execution System (MES) System to Control related parameters in a Manufacturing Process, thereby improving a line width, an overlay accuracy, and the like of a manufactured wafer.
For the line width control of wafers in the manufacturing process, the industry usually employs an average control method to predict the exposure energy, and uses the previous test data or production data to predict the exposure energy of the next batch of wafers so as to achieve the desired line width length.
In the APC system, the predicted exposure energy for the x-th exposure is calculated using an averaging method and set as the original exposure energy for the x + 1-th exposure. When the initial data calculation is performed, the deviation between the predicted exposure energy and the actual exposure energy may be large, and the influence of the initial value may be almost negligible as the number of rounds increases. That is, the line width control method based on the averaging method requires a large amount of test data for prediction, and the method has a large deviation of the exposure energy predicted in the initial stage. How to eliminate the phenomenon of large deviation of the predicted exposure energy in the initial stage of exposure is an urgent problem to be solved.
Disclosure of Invention
The invention aims to provide a line width control method applied to an advanced control system, which reduces the deviation of an initial period in a line width control process by correcting an average method, obtains better exposure energy prediction in an early stage and enables an exposed wafer to reach a line width standard more quickly.
In order to achieve the purpose, the invention adopts the following technical scheme: a line width control method applied to an advanced control system comprises the following steps: a line width control method applied to an advanced control system comprises the following steps:
s01: setting the original exposure energy E of the 1 st exposureexp(1) And carrying out exposure;
s02: after the 1 st exposure is completed, the actual exposure energy E of the 1 st exposure is calculatedl(1) And predicting exposure energy Ep(1) And E isp(1)＝E(1)/f(1)；
S03: repeating the steps S01-S02, setting the original exposure energy E of the x-th exposureexp(x) Predicted exposure energy E equal to the x-1 th exposurep(x-1), and performing exposure, and calculating the actual exposure energy E of the x-th exposurel(x) And predicting exposure energy Ep(x) (ii) a Until the whole exposure process is completed;
wherein the actual exposure energy El(x) Calculating according to the original exposure energy and the line width of the x-th exposure, E (x) represents the initial predicted exposure energy calculated by an average method, f (x) is a monotonically increasing adjustment formula, f (x) ∈ (0,1), and f (x) approaches to 1 along with the increase of x, wherein x is an integer larger than 0.
Further, the actual exposure energy E in the step S02l(x)＝[Eexp(x)-Slop×(CDtarget–CDmeasure)]×(SSC0/SSCm) (ii) a Wherein, CDtargetAnd CDmeasureThe target value and the measured value of the line width, SSC, of the x-th exposure0And SSCmThe initial value and the measured value of the position sensing coefficient of the exposure equipment are provided, and the Slop is a conversion coefficient of the line width and the exposure energy.
Further, the adjustment formula f (x) 1-QxQ is an adjustment coefficient, and Q ∈ (0, 1).
Further, in the step S02, the exposure energy E (x) E is initially predictedl(x)×(1-K)+Ep(x-1) × K, wherein K is an average coefficient, K ∈ (0, 1).
Further, the adjustment formula f (x) 1-Kx。
Further, the average coefficient K is (1-B) × D, where B is a weight coefficient and D is a time coefficient.
Further, the time coefficient D ═ C [ T- (T-1) ], C (T) ═ exp (-T/T), T denotes the duration of the entire exposure process, and the time of the xth exposure is the tth time after the start of exposure.
Further, the original exposure energy E of the first exposureexp(1)＝0。
The invention has the following beneficial effects: according to the invention, through correcting the average method, the deviation of the initial period in the line width control process is reduced, better exposure energy prediction is obtained in the early stage, the exposed wafer can reach the line width standard more quickly, and the line width control efficiency is effectively improved.
Drawings
FIG. 1 is a schematic diagram of the calculation of predicted exposure energy by an averaging method according to the present invention;
FIG. 2 is a graph showing the comparison of the predicted exposure energy in example 1 with the predicted exposure energy in the prior art.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings.
The invention provides a line width control method applied to an advanced control system, which comprises the following steps:
s01: setting the original exposure energy E of the 1 st exposureexp(1) And exposure is performed. In particular, a smaller raw exposure energy E can be setexp(1) Ensuring that the 1 st exposure does not break down the photoresist on the wafer; preferably, E may be setexp(1)＝0。
S02: after the 1 st exposure is completed, the actual exposure energy E of the 1 st exposure is calculatedl(1) And predicting exposure energy Ep(1) And E isp(1) E (1)/f (1). Wherein the actual exposure energy El(1) According to the 1 st exposureCalculating the original exposure energy and the line width; e (1) represents the initial predicted exposure energy calculated using the averaging method.
S03: repeating the steps S01-S02, setting the original exposure energy E of the x-th exposureexp(x) Predicted exposure energy E equal to the x-1 th exposurep(x-1), and performing exposure, and calculating the actual exposure energy E of the x-th exposurel(x) And predicting exposure energy Ep(x) (ii) a Until the whole exposure process is completed;
wherein the actual exposure energy El(x) Calculating according to the original exposure energy and the line width of the x-th exposure, E (x) represents the initial predicted exposure energy calculated by an average method, f (x) is a monotonically increasing adjustment formula, f (x) ∈ (0,1), and f (x) approaches to 1 along with the increase of x, wherein x is an integer larger than 0.
In particular, the actual exposure energy El(x)＝[Eexp(x)-Slop×(CDtarget–CDmeasure)]×(SSC0/SSCm) (ii) a Wherein, CDtargetAnd CDmeasureThe target value and the measured value of the line width, SSC, of the x-th exposure0And SSCmThe initial value and the measured value of the position sensing coefficient of the exposure equipment are provided, and the Slop is a conversion coefficient of the line width and the exposure energy. Actual exposure energy E of the x-th exposure in the present inventionl(x) Is calculated based on the original exposure energy (input value) of the x-th exposure, the line width target value of the x-th exposure, and the measured value.
In the present invention, f (x) satisfies the following conditions that f (x) is a monotone increasing formula, and f (x) ∈ (0,1), as x decreases, f (x) approaches to 0, and as x increases, f (x) approaches to 1xQ is an adjustment coefficient, and Q ∈ (0, 1).
Specifically, the initial predicted exposure energy may be calculated by the following formula: e (x) ═ El(x)×(1-K)+Ep(x-1) × K, wherein K is an average coefficient, K ∈ (0,1) the average coefficient can be calculated by the following formula, K ═ 1-B) × D, wherein B is a weight coefficient and D is a time coefficient;the time coefficient can be calculated using the following formula: d ═ C [ t- (t-1)]C (T) ═ exp (-T/T), T denotes the duration of the entire exposure process, and the time of the xth exposure is the tth time after the start of exposure. For example, if the duration of the entire exposure process is 20 days, and the xth exposure time is 5 hours after the start of exposure, T/T is 5/20 is 0.25. In the present invention, when the initial predicted exposure energy is calculated using the above formula, the adjustment formula is preferably f (x) 1-KxI.e. the adjustment coefficient equals the average coefficient.
The invention is suitable for exposure of a series of wafers, in the actual exposure process, the series of wafers can be divided into a plurality of batches for exposure respectively, for example, the series of wafers are divided into 10 batches for exposure respectively, each batch has 20 wafers, two adjacent batches of wafers are connected end to form 200 wafer exposures, the whole exposure process of the series of wafers comprises 200 exposures, and the original exposure energy of the 1 st exposure of the next batch is equal to the predicted exposure energy of the last exposure of the previous batch.
Because the corresponding relation exists between the line width value after exposure and the exposure energy, the invention calculates and predicts the exposure energy Ep(x) It is to determine the original exposure energy of the next exposure and further control the line width.
In the hardware, the invention can be provided with a controller and a storage unit, wherein the storage unit is used for storing the predicted exposure energy calculated each time, and the predicted exposure energy calculated each time is calculated by an averaging method, namely all the previous predicted exposure energy is considered. As shown in FIG. 1, the x-1 st predicted exposure energy E is stored in the memory unitp(x-1) (original exposure energy of the x-th exposure), the x-th actual exposure energy El(x) And adjusting the formula f (x) and inputting the formula f (x) into the controller to obtain the x-th predicted exposure energy.
Example 1
The line width control method applied to the advanced control system provided by this embodiment calculates the predicted exposure energy by using the following formula: ep(x)＝{El(x)×{1-(1-B)×C[t-(t-1)]}+Ep(x-1)×(1-B)×C[t-(t-1)]}/f(x)，And f (x) 1- { (1-B) × C [ t- (t-1)]X. Wherein E isp(x) Predicted exposure energy for the x-th exposure, El(x) B is a weight coefficient, c (T) exp (-T/T), T represents the duration of the entire exposure process, and the time of the xth exposure is the tth time after the start of exposure. For example, when the duration of the entire exposure process is 200 hours, and the x-th exposure time is 100 hours after the start of exposure, T/T is 100/200 is 0.5. The weight coefficients and the T in the formula are set according to different actual production lines.
Suppose El(1)＝20，Ep(0) 0, by calculation:
Ep(1)＝[0.15×El(1)+0.85×Ep(0)]/(1-0.85)＝20；
Ep(2)＝[0.15×El(2)+0.85×Ep(1)]/(1-0.852)＝0.54×El(2)+0.46×El(1)；
…
Ep(100)＝[0.15×Ep(100)+0.85×Ep(99)]/(1-0.85100)≈0.15×El(100)+0.85×Ep(99)。
it can be seen that the predicted exposure energy Ep(x) When the initial data calculation is performed, the deviation between the predicted exposure energy and the actual exposure energy is small.
If the predicted exposure energy E is calculatedp(x) Then, without correction of the adjustment formula, the above calculation method of the predicted exposure energy is still adopted, and at this time, the predicted exposure energy Ep’(x)＝El(x)×{1-(1-B)×C[t-(t-1)]}+Ep(x-1)×(1-B)×C[t-(t-1)]。
Suppose El(1)＝20，Ep' (0) ═ 0, by calculation:
Ep’(1)＝0.15×El(1)+0.85×Ep’(0)＝3；
Ep’(2)＝0.15×El(2)+0.85×Ep’(1)＝0.15×El(2)+0.1275×El(1)；
…
Ep’(100)＝0.15×Ep’(100)+0.85×Ep’(99)＝0.15×El(100)+0.15×0.85×El(99)+…+0.15×0.8599×El(1)；
can find Ep' (1) and Ep' (2) and the actual exposure energy El(1) 20 is far from each other, and as the number of rounds increases, the effect of the initial value is almost negligible. That is, the line width control method based on the averaging method requires a large amount of test data for prediction, and the method has a large deviation of the exposure energy predicted in the initial stage.
Comparing the conditions without the adjustment formula f (x) and with the adjustment formula f (x), the exposure energy E is predicted when the formula is not adjustedp' (x) when the initial data calculation is performed, the deviation between the predicted exposure energy and the actual exposure energy may be large. After adding the adjustment formula, the exposure energy E is predictedp(x) When the initial data calculation is performed, the deviation between the predicted exposure energy and the actual exposure energy is small.
As shown in FIG. 2, where in FIG. 2, pre-adjustment refers to predicted exposure energy without an adjustment formula and post-adjustment refers to predicted exposure energy with an adjustment formula, it can be seen that E with an adjustment formulap(1) And Ep(2) More conforms to El(1) True prediction case of 20.
According to the invention, through correcting the average method, the deviation of the initial period in the line width control process is reduced, better exposure energy prediction is obtained in the early stage, the exposed wafer can reach the line width standard more quickly, and the line width control efficiency is effectively improved.
The above description is only a preferred embodiment of the present invention, and the embodiment is not intended to limit the scope of the present invention, so that all equivalent structural changes made by using the contents of the specification and the drawings of the present invention should be included in the scope of the appended claims.

Claims (8)

1. A line width control method applied to an advanced control system is characterized by comprising the following steps:
s01: setting the original exposure energy E of the 1 st exposureexp(1) And carrying out exposure;
s02: after the 1 st exposure is completed, the actual exposure energy E of the 1 st exposure is calculatedl(1) And predicting exposure energy Ep(1) And E isp(1)＝E(1)/f(1)；
S03: repeating the steps S01-S02, setting the original exposure energy E of the x-th exposureexp(x) Predicted exposure energy E equal to the x-1 th exposurep(x-1), and performing exposure, and calculating the actual exposure energy E of the x-th exposurel(x) And predicting exposure energy Ep(x) (ii) a Until the whole exposure process is completed;
wherein the actual exposure energy El(x) Calculating according to the original exposure energy and the line width of the x-th exposure, E (x) represents the initial predicted exposure energy calculated by an average method, f (x) is a monotonically increasing adjustment formula, f (x) ∈ (0,1), and f (x) approaches to 1 along with the increase of x, wherein x is an integer larger than 0.
2. The method as claimed in claim 1, wherein the actual exposure energy E in step S02l(x)＝[Eexp(x)-Slop×(CDtarget–CDmeasure)]×(SSC0/SSCm) (ii) a Wherein, CDtargetAnd CDmeasureThe target value and the measured value of the line width, SSC, of the x-th exposure0And SSCmThe initial value and the measured value of the position sensing coefficient of the exposure equipment are provided, and the Slop is a conversion coefficient of the line width and the exposure energy.
3. The method as claimed in claim 1, wherein the adjustment formula f (x) is 1-QxQ is an adjustment coefficient, and Q ∈ (0, 1).
4. The method as claimed in claim 1, wherein the linewidth control method is applied to an advanced control systemIn step S02, the exposure energy E (x) E is initially predictedl(x)×(1-K)+Ep(x-1) × K, wherein K is an average coefficient, K ∈ (0, 1).
5. The method as claimed in claim 4, wherein the adjustment formula f (x) is 1-Kx。
6. The method as claimed in claim 4, wherein the average coefficient K is (1-B) × D, where B is a weighting coefficient and D is a time coefficient.
7. The method as claimed in claim 6, wherein the time coefficient D is C [ T- (T-1) ], C (T) is exp (-T/T), T represents the duration of the whole exposure process, and the time of the xth exposure is the tth time after the exposure is started.
8. The method as claimed in claim 1, wherein the raw exposure energy E of the first exposure isexp(1)＝0。
CN202010425461.9A 2020-05-19 2020-05-19 Line width control method applied to advanced control system Pending CN111427242A (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5473412A (en) * 1993-03-08 1995-12-05 Nikon Corporation Energy amount controlling method
CN103186051A (en) * 2011-12-27 2013-07-03 无锡华润上华科技有限公司 Method for setting exposure conditions in photoetching
CN103698985A (en) * 2014-01-09 2014-04-02 上海华虹宏力半导体制造有限公司 Prediction method of exposure energy parameter in photoetching pilot run
CN103841334A (en) * 2012-11-27 2014-06-04 原相科技股份有限公司 Exposure adjusting device, image homogenizing device and image homogenizing method

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5473412A (en) * 1993-03-08 1995-12-05 Nikon Corporation Energy amount controlling method
CN103186051A (en) * 2011-12-27 2013-07-03 无锡华润上华科技有限公司 Method for setting exposure conditions in photoetching
CN103841334A (en) * 2012-11-27 2014-06-04 原相科技股份有限公司 Exposure adjusting device, image homogenizing device and image homogenizing method
CN103698985A (en) * 2014-01-09 2014-04-02 上海华虹宏力半导体制造有限公司 Prediction method of exposure energy parameter in photoetching pilot run

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