JP2007258536A - Electron beam applied device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electron-beam applied device capable of determining correctly whether or not a contact state is good between an earth needle and a sample. <P>SOLUTION: The electron-beam applied device has a plurality of earth needles for being brought in contact with a front end surface of a sample; a current detection resistor connected to one of the earth needles; and also a determination means for calculating a resistance value of the sample containing a contact resistance from a potential difference between a sample resistance containing the contact resistance of the earth needle and the current detection resistance, and for determining whether or not the contact state between the earth needle and the sample is good, from the resistance value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electron beam application apparatus such as a semiconductor manufacturing apparatus or a semiconductor inspection apparatus, and relates to determining whether or not the contact of a ground needle used for a sample including a wafer and a mask is good.

  Judgment on whether or not the contact of the grounding needle to be brought into contact with the sample is good is disclosed in Japanese Patent Laid-Open No. 2005-127719 (Patent Document 1).

  The determination of the necessity of ground connection shown in Patent Document 1 is a method for confirming that the sample is connected to the ground by inserting the ground needle into the end surface of the sample. The book is disconnected from the earth line, a voltage is applied to the current through a current limiting resistor, current flows, and the comparator IC that compares the voltage between the earth voltage of the specimen and the reference voltage set by hardware is used to compare the sample. If the voltage between the ground needles is lower than the reference voltage, the ground check is OK. If the voltage is higher than the reference voltage, the ground check NG is used.

JP 2005-127719 A

  In an electron beam application device that irradiates a sample with an electron beam, confirm that the sample is securely grounded by the above-mentioned method using a ground needle inserted into the end surface of the sample to connect the sample to the ground. Yes.

  For this reason, even if a weak current flowing through the sample is short-circuited by a route other than the ground needle stuck in the sample, the voltage becomes lower than the determination reference voltage. Since the comparator IC only performs voltage comparison, The sample is misjudged to be grounded.

  And it was not possible to grasp whether the grounding needle stuck in the end face of the sample was stuck in the sample without any problem only by the information of the judged result.

  Further, when the sample is changed, the resistance value of the sample is different, so the setting of the reference voltage compared with the comparator IC must be changed.

  The present invention addresses the above problems, and an object of the present invention is to provide an electron beam application apparatus that can determine without error whether or not the contact state between a ground needle and a sample is good.

  The present invention has a plurality of grounding needles to be brought into contact with the front end surface of the sample, and a current detection resistor connected to one of the grounding needles, and the resistance of the sample and the current detection resistance including the contact resistance of the grounding needle And determining means for determining whether or not the contact state between the grounding needle and the sample is good based on the resistance value.

  According to the present invention, it is determined without error whether or not the contact state between the ground needle and the sample is good.

  As an example of an electron beam application apparatus to which the present invention is applied, FIG. 1 shows an electron beam drawing apparatus.

  FIG. 2 shows a schematic diagram of the earth check resistance measuring circuit of the present invention.

  FIG. 3 shows a contact diagram between the sample on the sample holder 115 and the ground needle.

  First, the outline of the electron beam drawing apparatus shown in FIG. 1 will be described.

  The mirror body of the electron beam drawing apparatus has an electron gun 1 on the top. The electron beam emitted from the electron gun 1 passes through the first shaping opening 2, the shaping deflector 3, and the shaping lens 4. Further, the electron beam passes through the second shaping aperture 5, the blanking electrode 6, the shaping beam 7, the reduction lens 8, the blanking stop 9, the objective lens 10, and the objective deflector 11 and is irradiated on the sample 13.

  The reflected electron detector 12 detects reflected electrons reflected from the sample 13. The position of the sample 13 is corrected by confirming the position of the calibration mark 14. The sample stage 15 carries the sample 13 by moving in the front-rear direction, the left-right direction, and the up-down direction.

  The shaping deflection control circuit 16 controls the shaping deflector 3 to adjust the aperture of the electron beam. The blanking control circuit 17 controls the blanking action of the blanking electrode 6. The objective deflection control circuit 18 controls the objective lens 10 and the objective deflector 11. The signal processing circuit 19 processes the reflected electron signal. The stage control circuit 20 controls the movement of the sample stage 15.

  The control computer 21 controls the overall operation control of the electronic drawing apparatus. The host computer that is above the control computer 21 performs comprehensive management related to electronic drawing.

  The earth check resistance measuring circuit shown in FIG. 2 will be described.

  The power supply 101 supplies a reference voltage. The first selector 105 selects the current detection resistor and switches the resistance measurement range. That is, the first selector 105 alternatively selects the current detection resistor A103 and the current detection resistor B104, and performs measurement in a range that matches the resistance value of the sample 13.

  The second selector 106 is switched to measure the reference resistance 102 and the ground check resistance of the sample 13, and the reference resistance 102 side is normally selected.

  When measuring the reference resistance 102, when the first selector 105 is switched to the resistance measurement range on the current detection resistor A 103 side and a reference voltage is supplied from the power supply 101, the current passes through the current detection resistor A 103, and the reference resistance 102 is The potential difference generated at both ends of the current detection resistor A103 by returning to the power source 101 is input to the differential amplifier circuit 111, and the output is A / D converted by the A / D converter 112 and the resistance measurement circuit constant. Then, the control microcomputer 113 calculates the reference resistance value.

  A constant resistance 108 is provided at the + terminal of the differential amplifier circuit 111, and a constant resistance 107 is provided at the − terminal. The potential difference is input through the constant resistors 108 and 107.

  Since the obtained reference resistance value deviates from the value of the reference resistance 102 due to variations in the earth check resistance measurement circuit, etc., a correction value for correcting variations in the earth check resistance measurement circuit is obtained.

  Then, the resistance measurement of the sample 13 is performed in the same manner as the measurement of the reference resistance value after switching the first selector 105 to the resistance measurement range on the current detection resistor A103 side and the second selector 106 to the sample resistance measurement side. Then, the ground check resistance value is calculated using the value obtained by A / D converting the potential difference between both ends of the current detection resistor A103, the resistance measurement circuit constant, and the correction value.

  This calculation result is compared with a threshold value (resistance value) set by the host computer to determine whether the sample is connected to the earth line through the earth needle.

  The host computer is a computer such as a workstation and stores a threshold value (resistance value) as a parameter value. The operator sets and stores the threshold value (resistance value) in the control microcomputer 113 simultaneously with the host computer. The control microcomputer 113 determines whether the earth check resistance value is good or not compared with a threshold value (resistance value).

  In this embodiment, the reference resistance 102 provided in the earth check resistance measurement circuit is measured to obtain a correction value due to circuit variations, and at the same time, the resistance measurement circuit is also checked.

  Then, in order to secure the ground of the sample 13, it is confirmed that the ground of the sample 13 is surely taken by the ground needle 114 which is brought into contact with the end face of the sample 13 as shown in FIG. 3.

  Note that the ground needle 114 is pressed against the sample 13 by the spring 116 to maintain contact.

  That is, in the resistance measurement circuit shown in FIG. 2, the second selector 106 is switched to the sample resistance measurement side, a reference voltage is applied, a weak current is passed between the ground needle 114 and the sample 13, and the ground needle 114 is contacted. The potential difference between the resistance of the sample 13 including the resistance and the current detection resistance is measured, and the resistance value of the sample 13 including the contact resistance is obtained by calculation using the previously obtained correction value. It is possible to determine whether the calculated value is within a threshold set from the upper level, and to simultaneously grasp the state of the ground needle, a problem on the circuit, and the like.

  Further, it is characterized in that it is possible to easily cope with a change in the type of the sample by changing the setting of the threshold value of the earth check resistance value corresponding to the resistance value of the sample accompanying the change in the sample type as a parameter value from the host computer.

  In the resistance measurement circuit shown in FIG. 2, when the resistance measurement between the ground needle 114 and the sample 13 is performed, a mechanism for selecting the current detection resistor A103 and the current detection resistor B104 by the selector 105 shown in FIG. It is characterized in that resistance measurement is performed while selecting a current detection resistor.

  In addition, in the first selector 105 shown in FIG. 2, the current detection resistor A103 and the current detection resistor B104 are alternatively selected, but the resolution of the resistance value to be measured can be reduced by providing three or more current detection resistors. It can be raised further.

  The resistance measurement circuit shown in FIG. 2 is provided with a mechanism for switching and measuring the reference resistor 102 and the ground check resistance of the sample 13 by the second selector 106. By measuring the reference resistance 102 provided in the earth check resistance measurement circuit, a correction value for correcting an error due to variations in the resistance measurement circuit can be obtained. At the same time, it is possible to check the resistance measurement circuit.

  The flowchart of the earth check process shown in FIG. 4 shows the process after confirming that the sample is normally set in the sample holder 115.

  In the earth check process, the earth needle mounted on the sample holder 115 is brought into contact with the end face of the sample (step 401), and the second selector 106 of the earth check resistance measuring circuit selects the reference resistor 102 side (step 402). ), The first selector 105 selects the current detection resistor A103 side (step 403), and calculates the reference resistance value and the correction value of the measurement circuit constant by calculation from the A / D conversion data and the measurement circuit constant (step 404). .

  Next, it is confirmed whether or not the calculated reference resistance value is within a predetermined range (step 405). If it is not within the range, it is determined that there is an abnormality in the resistance measurement circuit, an abnormality process is performed (step 406), and the process ends.

  If the reference resistance value is within a predetermined range, the second selector 106 selects the sample measurement side to measure the sample (step 407), and the A / D conversion value, measurement circuit constant, and correction value are selected. From this, the measured resistance value of the sample is obtained (step 408).

  Next, it is confirmed whether or not the measured A / D conversion value is larger than the switching value of the first selector 105 and the first selector 105 is on the current detection resistor A103 side (step 409). Is switched to the current detection resistor B104 side (step 410), the process returns to step 408, the sample resistance is measured again, and the resistance value is calculated.

In step 409, if the measured A / D conversion value is smaller than the switching value of the first selector 105, the resistance measurement result of the sample is compared with the threshold value corresponding to the sample set in advance by a parameter (step 409). 411), if the measurement result is within the threshold range,
“Earth Check Data = ****** [Ω], <OK>” ”is displayed (step 412).

  Otherwise, “Earth Check Data = ****** [Ω], <NG>” is displayed on the monitor (step 413).

    Here, the calculation result of the resistance value is displayed as an integer in ******.

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

  (1). The resistance value of the measurement object can be obtained by calculation.

  (2). By grasping the resistance value of the object to be measured, it is possible to determine whether the sample is normally connected to the ground.

  (3). Measurement can be performed by increasing the resolution of the resistance value of the object to be measured by selecting the current detection resistance value.

  (4). By measuring the reference resistance, the variation error of the earth check resistance measurement circuit can be corrected.

  (5). The change of the sample can be easily handled by parameter setting from the host computer by parameterizing the comparison data without changing the circuit settings.

1 is a schematic diagram of an electron beam drawing apparatus according to an embodiment of the present invention. FIG. 5 is a schematic diagram of an earth check resistance measuring circuit according to an embodiment of the present invention. FIG. 6 is a contact diagram of a sample and a ground needle according to an embodiment of the present invention. It is a flowchart of an earth check process in connection with the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... 1st shaping | molding opening, 3 ... Molding deflector, 4 ... Molding lens, 5 ... 2nd shaping | molding opening, 6 ... Blanking electrode, 7 ... Molding beam, 8 ... Reduction lens, 9 ... Blanking Aperture, 10 ... objective lens, 11 ... objective deflector, 12 ... backscattered electron detector, 13 ... sample, 14 ... calibration mark, 15 ... sample stage, 16 ... shaping deflection control circuit, 17 ... blanking control circuit, 18 ... Objective deflection control circuit, 19 ... signal processing circuit, 20 ... stage control circuit, 21 ... control computer, 101 ... power supply, 102 ... reference resistor, 103 ... current detection resistor A, 104 ... current detection resistor B, 105 ... first Selector 106 ... second selector 107,108 resistor 111 ... amplifier 112 ... A / D converter 113 ... control microcomputer 114 ... grounding needle 115 ... sample holder 116 ... spring

Claims (6)

  A plurality of grounding needles to be brought into contact with the front end surface of the sample, and a current detection resistor connected to one of the grounding needles, and a potential difference between the resistance of the sample including the contact resistance of the grounding needle and the current detection resistance An electron beam application apparatus comprising: a determination unit that calculates a resistance value of a sample including the contact resistance and determines whether or not a contact state between the ground needle and the sample is good based on the resistance value.   A plurality of grounding needles to be brought into contact with the front end surface of the sample, a current detection resistor connected to one of the grounding needles, and the contact resistance based on a potential difference between the resistance of the sample including the contact resistance of the grounding needle and the current detection resistance An electron beam application apparatus comprising: calculating a resistance value of a sample including the element and comparing the resistance value with a threshold value to determine whether or not a contact state between the ground needle and the sample is good.   A plurality of grounding needles that are brought into contact with the front end surface of the sample, a current detection resistor connected to one of the grounding needles, and a difference that amplifies the potential difference between the resistance of the sample including the contact resistance of the grounding needle and the current detection resistance An electron beam application apparatus comprising: a dynamic amplifier; and determination means for determining whether or not a contact state between the ground needle and the sample is good based on an output of the differential amplifier. In the electron beam application apparatus of Claim 3,
An electron beam application apparatus comprising: a plurality of current detection resistors having different resistance values; and a first selector that selects the current detection resistors. In the electron beam application apparatus of Claim 3,
Provide a reference resistor in parallel with the sample,
2. An electron beam application apparatus comprising a second selector for selectively connecting the current detection resistor to the reference resistor or the sample. In the electron beam application apparatus of Claim 2,
An electron beam application apparatus comprising a threshold value of a resistance value corresponding to a type of sample, and the threshold value is selected according to the type of sample.

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