JP2009139092A - Capacitance type multipoint thickness measurement method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch on and off the contact state between an earth electrode and a measuring object according to measurement conditions of the measuring object in which, for example, contamination on a surface of a semiconductor wafer etc. due to metal ions or contact damage on the earth electrode should be avoided, or contrarily such a condition should not be taken into much consideration. <P>SOLUTION: The capacitance type multipoint thickness measurement device for performing multipoint measurement of the thickness at a plurality of measured portions P<SB>1</SB>, P<SB>2</SB>, P<SB>3</SB>of a measuring object comprises: a pair of capacitance type distance detecting sensors S<SB>1</SB>/S<SB>2</SB>which are disposed in opposite positions, across the measured portion P of the measuring object W, at a predetermined distance G<SB>S</SB>from each other; and a connection/disconnection mechanism 13 which can switch on and off the contact state between an earth electrode 8 and the measuring object according to measurement conditions of the measuring object. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrostatic capacitance type multi-point measuring method and apparatus for measuring the thickness of an object to be measured such as a semiconductor wafer in a non-contact manner with respect to the object to be measured by an electrostatic capacitance type distance detection sensor.

Conventionally, as this type of capacitance type thickness multipoint measurement method, as shown in FIGS. 9 and 10, for example, a measurement site P of a measurement object W, which is a semiconductor wafer, in this case, P ₁ , P ₂ , P _A pair of electrostatic capacitance type distance detection sensors S ₁ and S ₂ is arranged at a position opposed to each other with a predetermined facing distance Gs 3 therebetween, and is in contact with or not in contact with the object W to be measured. An earth electrode Q is arranged and the capacitance C detected by each of the pair of capacitance type distance detection sensors S ₁ and S ₂ (= electrode area A of the sensor × dielectric constant ε / electrode between the electrode and the measured object) distance G ₁ · G ₂ and a pair of electrostatic capacitance type distance sensor S and the capacitance type distance sensor S ₁ · S ₂ of the measurement object W and the pair of the place due to the distance G) between the object to be measured ₁ · S ₂ between the facing distance Gs thickness of the plurality of the measurement site P of the object to be measured based on the _{t (= Gs- [G 1 +} G 2 ) As a structure that multiple points measured by non-contact with the object to be measured is known.

In these conventional structures, a contact-type structure in which the ground electrode Q is in contact with the measured object W or a non-contact state in which the ground electrode Q is not in contact with the measured object W. A contact type structure coexists. This is because the ground electrode holds the object to be measured and the capacitance type distance detection sensor at substantially the same potential, and measures the distances G ₁ and G ₂ between the object to be measured and the pair of capacitance type distance detection sensors. It is provided for the purpose of accurate thickness measurement with as little error as possible. When the object to be measured is a semiconductor wafer such as a silicon wafer, the contact structure described above may cause contamination by metal ions or grounding. The non-contact type structure is selected because of concerns such as scratches due to electrode contact. On the other hand, in the case of the contact type structure, the ground electrode is always in contact with the object to be measured. In the case of an object to be measured, it is easy to handle various types of processing such as simplifying the measurement and taking in / out the object to / from the sensor. This is because the contact type structure is adopted.
JP-A-2005-172700

  However, as described above, conventionally, the ground electrode Q is in a contact-type structure in contact with the measured object W or the non-contact state in which the ground electrode Q is not in contact with the measured object W. Since the contact-type structure coexists, there is a disadvantage that the flexibility of measurement with respect to the measurement conditions of various objects to be measured may be lowered.

  The present invention is intended to solve these disadvantages. Among the present inventions, in the method invention according to claim 1, the measurement object is measured at a position facing the measurement site. A pair of electrostatic capacitance type distance detection sensors are arranged at a predetermined facing distance, an earth electrode is arranged opposite to the object to be measured, and static electricity detected by each of the pair of electrostatic capacitance type distance detection sensors is detected. Based on the distance between the object to be measured and the pair of capacitance type distance detection sensors due to capacitance and the opposing distance between the pair of capacitance type distance detection sensors, the thicknesses of the plurality of measurement parts of the object to be measured are determined. In the capacitance-type thickness multipoint measurement method for multipoint measurement, the ground electrode and the object to be measured are switched to a contact state or a non-contact state according to a measurement condition of the object to be measured. It is in the capacity type multipoint measuring method.

  Further, in the invention of the device according to claim 2, a pair of electrostatic capacitance type distance detection sensors are arranged at a predetermined facing distance at positions facing each other with the measurement site of the measurement object as a boundary, A ground electrode is disposed opposite to the measurement object, and the distance between the measurement object and the pair of capacitance distance detection sensors by the capacitance detected by each of the pair of capacitance distance detection sensors And an electrostatic capacitance type multi-point measuring device for measuring the thickness of a plurality of measurement sites of the measurement object based on the opposing distance between the pair of electrostatic capacitance type distance detection sensors. The capacitance type multi-point measuring device is characterized in that a measuring body is provided with a contact / separation mechanism that can be switched between a contact state and a non-contact state according to the measurement conditions of the object to be measured.

  The invention described in claim 3 is characterized in that the ground electrode is a mounting table on which the object to be measured can be mounted, and the invention described in claim 4 is characterized by the separation. The mechanism is characterized by having a structure in which the object to be measured placed in contact with the placement table as the ground electrode is in a non-contact state by levitating from the placement table, The invention described in claim 5 is characterized in that an indexing mechanism capable of indexing and rotating the measured object is provided, and the invention described in claim 6 is characterized in that the measured object. It is characterized by comprising a positioning portion capable of positioning the outer peripheral end portion of the.

  As described above, according to the first or second aspect of the present invention, a pair of capacitance-type distance detection sensors are provided with a predetermined facing distance at a position facing each other with the measurement site of the measurement object as a boundary. And a ground electrode opposite to the object to be measured, and the object to be measured and the pair of capacitance distances by the capacitance detected by each of the pair of capacitance type distance detection sensors. Based on the distance to the detection sensor and the facing distance between the pair of capacitance type distance detection sensors, the thickness of a plurality of measurement parts of the measurement object is measured at multiple points. Since a contact / separation mechanism that can switch the measured object to a contact state or a non-contact state according to the measurement conditions of the measured object is provided, contamination of the surface of a semiconductor wafer or the like by metal ions or a ground electrode Must avoid scratches caused by contact Depending on the measurement conditions of the object to be measured, such as when there is no need to consider so much contamination, surface contamination, or scratches due to contact with the earth electrode, the earth electrode and the object to be measured are in contact or non-contact. Therefore, the flexibility of measurement with respect to the measurement conditions of various objects to be measured can be improved.

  In the invention described in claim 3, since the ground electrode is a mounting table on which the object to be measured can be mounted, the structure can be simplified by double use. In the invention, the separation mechanism has a structure in which the measurement object placed in contact with the placement table as the ground electrode is floated from the placement table to be in a non-contact state. Therefore, the structure of the separation mechanism can be simplified, and the invention according to claim 5 is provided with an indexing mechanism capable of indexing and rotating the object to be measured. Positioning of the body in the rotational direction can be easily performed, and the invention according to claim 6 is provided with a positioning portion capable of positioning the outer peripheral end of the body to be measured. The surface can be prevented from being scratched.

  1 to 8 show an embodiment of the present invention. Reference numeral 1 denotes a machine base. In this case, a moving stage 2 is mounted on the machine base 1 by a guide mechanism 3 including a guide rail 3a and a linear bearing portion 3b. The moving stage 2 is provided with a handle 2a, a positioning mechanism 4 is provided between the moving stage 2 and the machine base 1, and a rotating stage 5 is rotated on the moving stage 2 by a main shaft 6. The rotating stage 5 is provided so as to be freely indexable by the indexing mechanism 7, and a mounting table 9 serving as a ground electrode 8 is attached to the rotating stage 5 so as to be measured. A ground electrode 8 is arranged opposite to W.

Further, in this case, the measuring machine body 10 is erected on the machine base 1, the upper arm part 10a and the lower arm part 10b are formed in the measuring machine body 10 by the insertion groove part 11, and the upper arm part 10a and the lower arm part 10b are A pair of electrostatic capacitance type distance detection sensors S ₁ and S ₂ is arranged at a position facing each other with the measurement part P of the measurement object P as a boundary at the distal end, and the rotary stage. 5 and the upper arm portion 10a and the lower arm portion 10b is formed can be inserted relief groove M in the mount table 9 serving as a grounding electrode 8, the machine frame 1 to be positioned to the outer peripheral edge portion W ₁ of the object to be measured W the Do positioning unit 12 is provided, the positioning portion 12 is constituted by upright three positioning pins 12b positionable the outer peripheral end portion W ₁ of the workpiece W on the positioning base 12a.

In this case, the positioning mechanism 4 includes a pressure ball 4a provided on the back surface of the movable stage 2, a spring 4b capable of pressing the pressure ball 4a, a supply take-out position A, a measurement position B (P ₁ ),. (P ₂ ) · D (P ₃ ) includes a positioning plate 4d formed with a recessed concave ball portion 4c in which a part of the elastic ball 4a is immersed and locked to position the movable stage 2, and the positioning plate 4d The indexing mechanism 7 is provided with an elastic ball 7a provided on the upper surface of the movable stage 2 and a spring 7b capable of pressing the elastic ball 7a. At the exit position, a part of the pressure ball 7 a is immersed and locked, and an immersion concave ball portion 7 c that can position the rotation stage 5 is formed on the bottom surface of the rotation stage 5.

  13 is a contact / separation mechanism, which is formed so that the mounting table 9 as the ground electrode 8 and the measured object W can be switched to a contact state or a non-contact state according to the measured object W. In this case, The separation mechanism 13 has a structure in which the object to be measured W placed in contact with the placement table 9 as the ground electrode 8 is lifted from the placement table 9 to be in a non-contact state. 4 and 5, a plurality of mounting pins 14 are screwed up on the rotary stage 5, and fitting holes 15 that can be fitted into the mounting pins 14 are formed in the mounting table 9 that is the ground electrode 8. An adjustment bolt 16 that is formed and capable of pressing the upper surface of the rotary stage 5 is screwed to the mounting table 9 serving as the ground electrode 8, and the ground electrode 8, the object W to be measured, Can be switched to a contact state or a non-contact state. There.

  As shown in FIG. 4, the adjustment bolt 16 of the contact / separation mechanism 13 is loosely rotated to move the tip of the adjustment bolt 16 away from the rotary stage 5, and the ground electrode 8 is fitted with the adjustment bolt 16. The weight of the object to be measured W is lowered by the fitting and sliding with the joint hole 15, the object to be measured W is placed on the upper surface of the plurality of placement pins 14, and the object to be measured W is levitated from the placement table 9 which is the ground electrode 8. As a result, the ground electrode 8 and the measured object W are not in contact with each other with a slight gap T, and the adjusting bolt 16 of the contact / separation mechanism 13 is tightened and rotated as shown in FIG. Thus, the tip of the adjustment bolt 16 presses the rotary stage 5, the mounting table 9 as the ground electrode 8 is raised by the fitting sliding of the adjustment bolt 16 and the fitting hole 15, and the upper end surface of the mounting pin 14 is The object to be measured W is immersed from the upper surface of the ground electrode 8 and The ground electrode 8 and the object to be measured W are brought into contact with each other, so that the adjustment bolt 16 of the contact / separation mechanism 13 is rotated forward and backward. Thus, the ground electrode 8 and the measurement object W are switched to a contact state or a non-contact state.

  Further, in this case, as the position fixing mechanism 17 of the object to be measured W, a suction hole 17a is formed in the mounting pin 14, and the rotary stage 5 communicates with the suction hole 17 and is connected to a negative pressure source (not shown). The suction path 17b is formed and configured.

Since this embodiment is configured as described above, the object to be measured W is placed on the ground electrode 8 serving as the placement table 9 at the take-out supply position A as shown in FIGS. 1, 2, 3, and 10. Then, the movable stage 2 is moved forward, and at the measurement position B, the pair of electrostatic capacitance type distance detection sensors S ₁ and S ₂ are positioned at a predetermined facing distance with the measurement site P ₁ of the workpiece W as a boundary. is the distance between the pair of capacitive distance detection sensor S ₁ · object to be measured where by electrostatic capacitance detected by each of S ₂ W and a pair of electrostatic capacitance type distance detecting sensor S ₁ · S ₂ G Thickness t (= Gs− [G ₁ + G ₂ ]) of a plurality of measurement sites P ₁ of the measured object based on ₁ · G ₂ and the opposing distance Gs between the pair of capacitance type distance detection sensors S ₁ and S ₂ ) Is measured, and in this state, the rotary stage 5 is rotated by a predetermined angle, and at this angular rotation position, Detecting the thickness by an electrostatic capacitance type distance detecting sensor S ₁ · S ₂ pairs, the rotation stage 5 rotated by a predetermined angle as measured multi point, then further moved forward movement stage 2, in the measurement position C, is positioned a pair of electrostatic capacitance type distance detecting sensor S ₁ · S ₂ at a predetermined opposing distance measurement site P ₂ in the boundary of the object W, S ₁ · pair of capacitive distance sensor The thickness t of the measurement site P ₂ is measured by S ₂ , and in this state, the rotary stage 5 is rotated by a predetermined angle, and at this angular rotation position, the thickness is measured by the pair of capacitance type distance detection sensors S ₁ and S _2. Then, the rotary stage 5 is rotated at a predetermined angle and measured at multiple points. Thereafter, the movable stage 2 is further moved forward, and the thickness of the measurement site P ₃ at the center position of the measurement object W is measured at the measurement position D. This makes it possible to measure the thickness of the object to be measured W at multiple points. It will be constant.

  At this time, since the ground electrode 8 and the object to be measured W are provided with the contact / separation mechanism 13 that can be switched between a contact state and a non-contact state according to the measurement conditions of the object to be measured W. In the measurement conditions of the measurement object W that must avoid contamination by metal ions on the surface of the wafer or the like or contact with the ground electrode, the ground electrode 8 and the measurement object W are connected as shown in FIG. The measurement conditions of the measurement object W can be measured in a non-contact state according to the measurement conditions of the measurement object W, and the surface contamination and scratches due to the contact with the ground electrode need not be considered so much. In this case, as shown in FIG. 5, the ground electrode 8 and the measured object W can be measured in contact with each other according to the measurement conditions of the measured object W. Therefore, various measured objects W can be measured. For measurement conditions It is possible to improve the facultative.

In this case, since the ground electrode 8 is a mounting table 9 on which the object to be measured W can be mounted, the structure can be simplified by double use. In this case, the separation mechanism 13 is connected to the ground. Since the measurement object placed in contact with the placement table 9 as the electrode 8 is lifted from the placement table 9 and brought into a non-contact state, the structure of the separation mechanism 13 is simplified. In this case, since the indexing mechanism 7 capable of indexing and rotating the object to be measured W is provided, positioning of the object to be measured W in the rotation direction can be easily performed. In this case, since the positioning portion 12 capable of positioning the outer peripheral end W ₁ of the measurement object W is provided, the surface of the measurement object W can be prevented from being damaged.

The present invention is not limited to the above-described embodiment, and the grounding electrode is positioned opposite to the measurement object W separately from the mounting table without using the mounting table as a grounding electrode. There may be a structure to provide a contact / separation mechanism that can switch the ground electrode provided and the object to be measured to a contact state or a non-contact state according to the object to be measured. The stage 2 may be eliminated, and instead of this, a structure may be adopted in which a scanning mechanism capable of scanning by moving the pair of capacitance type distance detection sensors S ₁ and S ₂ in the radial direction of the measurement target W is provided. In addition, the structure of the ground electrode 8, the structure of the contact / separation mechanism 13 and the like are designed as appropriate.

  As described above, the intended purpose can be sufficiently achieved.

1 is an overall side view of an embodiment of the present invention. 1 is an overall plan view of an embodiment of the present invention. 1 is an overall side view of an embodiment of the present invention. It is a partial longitudinal cross-sectional view of implementation of this invention. It is a partial longitudinal cross-sectional view of implementation of this invention. It is a partial side view of the embodiment of the present invention. It is a fragmentary top view of the example of an embodiment of the invention. 1 is an overall side view of an embodiment of the present invention. It is a measurement principle explanatory drawing. It is a multipoint measurement explanation top view.

Explanation of symbols

W measurement object P measurement site S ₁ capacitance type distance detection sensor S ₂ capacitance type distance detection sensor W ₁ outer peripheral end 7 indexing mechanism 8 ground electrode 9 mounting table 12 positioning unit 13 contact / separation mechanism

Claims (6)

  A pair of capacitance type distance detection sensors are arranged at a predetermined facing distance at a position facing each other with the measurement site of the measurement object as a boundary, and a ground electrode is arranged opposite to the measurement object, The distance between the object to be measured and the pair of capacitance type distance detection sensors by the capacitance detected by each of the capacitance type distance detection sensors and the opposing distance between the pair of capacitance type distance detection sensors In the capacitance-type thickness multipoint measurement method for measuring the thickness of a plurality of measurement sites of a measurement object based on the above, the ground electrode and the measurement object are contacted according to the measurement conditions of the measurement object Capacitance-type thickness multipoint measurement method characterized by switching to a state or a non-contact state.   A pair of capacitance type distance detection sensors are arranged at a predetermined facing distance at a position facing each other with the measurement site of the measurement object as a boundary, and a ground electrode is arranged opposite to the measurement object, The distance between the object to be measured and the pair of capacitance type distance detection sensors by the capacitance detected by each of the capacitance type distance detection sensors and the opposing distance between the pair of capacitance type distance detection sensors In the electrostatic capacitance type thickness multipoint measuring device for measuring the thickness of a plurality of measurement sites of the measurement object based on the above, the ground electrode and the measurement object are contacted according to the measurement conditions of the measurement object An electrostatic capacitance type multi-point measuring device comprising a contact / separation mechanism that can be switched between a state and a non-contact state.   3. The capacitance-type thickness multipoint measuring device according to claim 2, wherein the ground electrode is a mounting table on which the object to be measured can be mounted.   The separation mechanism has a structure in which a measurement object placed in contact with the placement table as the ground electrode is lifted from the placement table to be in a non-contact state. Item 4. The capacitance-type thickness multipoint measuring device according to Item 3.   5. The capacitance type multi-point measuring device according to claim 2, further comprising an indexing mechanism capable of indexing and rotating the object to be measured. The capacitance-type thickness multipoint measuring device according to claim 2, further comprising a positioning portion that can position an outer peripheral end portion of the measurement object.

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