JPH0488652A - Manufacture of silicon wafer - Google Patents

Abstract

PURPOSE:To simplify a measurement operation and enable the interlattice oxygen concentrations of all the lifted silicon wafers to be checked at a required point in a manufacturing line by a method wherein a floating zone silicon wafer whose both sides are mirror-polished is made to serve as a reference as it is. CONSTITUTION:The interlattice hydrogen concentration of a lifted silicon wafer whose front side is mirror-polished (one-side polished lifted silicon wafer) is measured through a computing device 15. Thereafter, the interlattice oxygen concentration of the lifted wafer whose rear side is mirror-polished (double-side polished lifted silicon wafer) is measured in this state through the device 5. The one-side polished lifted silicon wafer and the double-side polished floating zone silicon wafer are adopted as a specimen M and a reference R respectively as they are, whereby the inter-lattice oxygen concentration of a lifted silicon wafer can be directly measured in a manufacturing line. By this setup, the inter-lattice oxygen concentrations of all the lifted silicon wafers can be measured at a required point in a manufacturing line.

Description

Detailed Description of the Invention (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a method for manufacturing silicon wafers, and in particular,
Light transmission characteristics measured by incident parallel polarized light at the Brewster angle on a pulled silicon wafer whose surface has been mirror polished in a mirror polishing process, and parallel polarized light on a control floating zone silicon wafer whose front and back surfaces have been mirror polished. By calculating the interstitial oxygen concentration of the pulled silicon wafer from the light transmission characteristics measured by making it incident at the Brewster angle and comparing it with the reference value, pulled silicon wafers with poor interstitial oxygen concentration can be excluded. The present invention relates to a method for manufacturing silicon wafers.

[Conventional technology] Conventionally, the method for manufacturing this type of silicon wafer is as follows:
A pulled silicon wafer whose front surface has been mirror polished in a mirror polishing process and whose back surface has been roughened for the purpose of making it easy to distinguish between the front and back surfaces in a wafer processing process subsequent to the mirror polishing process, and which has been extracted from a production line; Simultaneous incidence of infrared light on a reference floating zone silicon wafer whose front surface is mirror polished and whose back surface is roughened to ensure the same optical behavior as the back surface of a pulled silicon wafer. By measuring the light transmission characteristics of the pulled silicon wafer and the light transmission characteristics of the floating zone silicon wafer, the interstitial oxygen concentration of the pulled silicon wafer was determined.
A system has been proposed that determines whether a pulled silicon wafer is defective or not based on the determined interstitial oxygen concentration.

[Problems to be solved] However, in the conventional silicon wafer manufacturing method, the pulled silicon wafer and the floating zone silicon wafer are assumed to have the same optical behavior, so li) measurement work is complicated and time-consuming; There are drawbacks and even more! ii! (iii) It is virtually impossible to inspect all the pulled silicon wafers on the production line, and (iii) unnecessary processing is performed on defective pulled silicon wafers. (There was a drawback that the productivity of the IVL production line could not be improved.

Therefore, in order to eliminate these drawbacks, the present invention simplifies the measurement work by making it possible to use a floating zone silicon wafer whose front and back surfaces are mirror-polished as a control, and to improve the interstitial oxygen concentration of the pulled silicon wafer. It is an object of the present invention to provide a method for manufacturing silicon wafers that enables 100% inspection of concentration at a desired location in a manufacturing line.

(2) Structure of the Invention (c) Means for Solving Problems] The means for solving problems provided by the present invention is as follows: ``A single treatment process including a mirror polishing process is performed on a wafer cut from a pulled silicon single crystal. In a method of manufacturing a silicon wafer, the pulled silicon wafer is produced by (a) parallel polarized light is incident at the Brewster angle on the pulled silicon wafer whose surface has been mirror-polished by a mirror polishing process. a first step for measuring light transmission characteristics to the upper silicon wafer;

(b) a second step for measuring the light transmission characteristics of the floating zone silicon wafer by making parallel polarized light incident at the Brewster angle on a floating zone silicon wafer as a control whose front and back surfaces are mirror-polished; c) To calculate the interstitial oxygen concentration of the pulled silicon wafer from the light transmission characteristics of the bowed silicon wafer measured in the first step and the light transmission characteristics of the floating zone silicon wafer measured in the second step. (d) a fourth step for comparing the interstitial oxygen concentration of the pulled silicon wafer calculated in the third step with a reference value; and a fifth step of eliminating arched silicon wafers with poor interstitial oxygen concentration according to the results of the process.

[Function] As clearly stated in [Means for solving problem E above], the method for manufacturing a silicon wafer according to the present invention improves the light transmission characteristics of a pulled silicon wafer whose surface has been polished i*'i by a mirror polishing process. By calculating the interstitial oxygen concentration of the pulled silicon wafer from the light transmission characteristics of the floating zone silicon wafer whose front and back surfaces are mirror-polished and comparing it with a standard value, pulled silicon wafers with poor interstitial oxygen concentration can be eliminated. Therefore, fi) the back surface of a floating zone silicon wafer whose front and back surfaces are mirror-polished can be used as a mirror surface without being roughened, and fii) the interstitial oxygen concentration of the pulled silicon wafer can be lowered. (iii) The interstitial oxygen concentration of pulled silicon wafers can be measured by 100% inspection at a desired location in the production line, resulting in (1v ) It acts to improve the productivity of the manufacturing line.

[Example] Next, the method for manufacturing a silicon wafer according to the present invention will be specifically described by giving preferred examples and referring to the accompanying drawings.

FIG. 1 is a simplified configuration diagram showing a measuring device for carrying out the first embodiment of the silicon wafer manufacturing method according to the present invention.

FIG. 2 is a simplified configuration diagram showing a transfer device for carrying out the first embodiment of the silicon wafer manufacturing method according to the present invention.

FIGS. 3 and 4 are explanatory diagrams for explaining one embodiment of the silicon wafer manufacturing method according to the present invention.

No. 1 - First, the structure and operation of the first embodiment of the silicon wafer manufacturing method according to the present invention will be described in detail.

In the silicon wafer manufacturing method according to the present invention, after the cleaning step that is performed in conjunction with the mirror polishing step in the manufacturing line, the interstitial oxygen concentration measurement step is performed prior to the gettering step.

That is, the measurement step in the method of manufacturing a silicon wafer according to the present invention is performed on a pulled silicon wafer (referred to as a "single-sided polished pulled silicon wafer") whose surface has been mirror-polished in a mirror polishing process in the manufacturing line and cleaned in a cleaning process. To measure the light transmission characteristics (here, transmitted light intensity) of pulled silicon wafers (i.e., single-sided polished pulled silicon wafers) by making parallel polarized light incident at Brewster's angle φ. The floating zone silicon wafer (referred to as the "double-sided polished floating zone silicon wafer") is made of floating zone silicon by making parallel polarized light incident at the Brewster angle φ. A second step for measuring the light transmission characteristics (here, transmitted light intensity) of a wafer (i.e., a double-sided polished floating zone silicon wafer) and a pulled silicon wafer ( The optical transmission properties of the floating zone silicon wafer (i.e., the double-sided polished floating zone silicon wafer) measured by the second step (here, the transmitted light intensity) are The third step is to calculate the interstitial oxygen concentration [olcl of the pulled silicon wafer from , CI is compared with the reference value, and the interstitial oxygen concentration [o, cl is determined depending on the result of the comparison in the fourth step.
and a fifth step for excluding pulled silicon wafers (for example, exceeding a reference value).

1st. In the second step, the Brewster angle ψ 3 for pulled silicon wafers (i.e., single-sided polished pulled silicon wafers) and floating zone silicon wafers (i.e., double-sided polished floating zone silicon wafers), respectively.
The basis for making parallel polarized light incident on a pulled silicon wafer (i.e., a single-sided polished pulled silicon wafer) and a floating band silicon wafer (i.e., a double-sided polished floating band silicon wafer) is based on the fact that reflection occurs when parallel polarized light enters and exits the pulled silicon wafer (i.e., a double-sided polished floating band silicon wafer). The objective is to substantially prevent multiple reflections from occurring within pulled silicon wafers (ie, single-sided polished pulled silicon wafers) and floating zone silicon wafers (ie, double-sided polished floating zone silicon wafers). Here, parallel polarized light refers to polarized light having only a component parallel to the plane of incidence on the incident object (here, a single-sided polished pulled silicon wafer and a double-sided polished floating zone silicon wafer). In addition, a pulled silicon wafer is a wafer cut from a silicon single crystal (referred to as pulled silicon single crystal) manufactured by a pulling method (so-called "Czochralski method"), which undergoes a mirror polishing process. Refers to silicon wafers that have been processed through different processing steps, including processing, and the back side is usually left rough to make it easier to distinguish between the front and back surfaces in subsequent wafer processing steps. A zone silicon wafer refers to a silicon wafer made from a silicon single crystal produced by a floating zone melting method.

The reason why the floating zone silicon wafer is used as a control in the second step is that its interstitial oxygen concentration [0□1 is extremely small compared to the interstitial oxygen concentration [0, c] of the pulled silicon wafer. It is in. Further, the reason why both the front and back surfaces of the floating zone silicon wafer are mirror-polished is to prevent incident light (here, parallel polarized light) from being scattered on both the front and back surfaces.

In the third step, the light transmission characteristics (in this case, transmitted light is strong.
Floating zone measured by the process of silicon wafer (
In other words, the procedure for calculating the interstitial oxygen concentration [O, C] of the pulled silicon wafer from the light transmission characteristics (in this case, the transmitted light is strong) of the double-sided polished floating zone silicon wafer is as follows.

First, the interstitial oxygen concentration [otc
l is the light absorption coefficient (also referred to as "light absorption coefficient of the pulled silicon wafer") α2 caused by the vibration of interstitial oxygen in the pulled silicon wafer and the conversion coefficient k (currently 3.03X 10
The optical absorption coefficient αg of the pulled silicon wafer is the thickness d at a wave number of 1106 cm.
Using the absorbance A of the pulled silicon wafer of and the optical path length β of parallel polarized light incident at Brewster angle φ1 = 1.041d, from the Beer-Lambert law, the pulled silicon wafer (゛The light transmission characteristics of a floating band silicon wafer (also referred to as a “double-sided polished pulled-up silicon wafer”) and the light transmission characteristics of a floating zone silicon wafer (i.e. a double-sided polished floating zone silicon wafer)
Here, it can be expressed using the transmitted light intensity Io), so the light transmission characteristics (in this case, the transmitted light is strong) due to light absorption by interstitial oxygen of a single-sided polished pulled-up silicon wafer, It can be expressed as follows using the light transmission characteristics of a polished floating zone silicon wafer (in this case, the transmitted light is strong) and the light scattering characteristics on the back side of a single-sided polished pulled-up silicon wafer (in this case, the scattered light intensity is 1.1).

Therefore, the interstitial oxygen concentration of the pulled silicon wafer [
0□,] can be expressed as follows.

The absorbance A of the pulled silicon wafer is determined for both the front and back surfaces.

The sum of the light transmission characteristics of the upper silicon wafer (in this case, transmitted light is a strong devil. 3.) and the light scattering characteristics on the back side of the single-sided polished pulled-up silicon wafer (here, the scattered light intensity is 1), and the double-sided polished floating zone silicon wafer. It can be calculated from the absorbance characteristic, which is the natural logarithm of the reciprocal of the ratio of
m-' absorbance characteristic (i.e. peak ([)
and the value on the asymptote of the absorbance characteristic at a wave number of 1106 cm"' as shown in FIG. 2.

1. Also, with reference to FIGS. 1 and 2, the configuration and operation of the measuring device for carrying out the first embodiment of the silicon wafer manufacturing method according to the present invention will be explained in detail. do.

IO is a measuring device (also simply referred to as “measuring device”) for carrying out the silicon wafer manufacturing method according to the present invention.
The light source 11, such as a Grover lamp, and the light given from the light source 11 are divided into two by a semitransparent mirror 1112A, reflected by a movable mirror 12B and a fixed mirror 12C, and then overlapped to form interference light. The Michelson interferometer 12 and the parallel polarized light obtained by polarizing the light (that is, interference light) given from the Michelson interferometer 12 are transferred to a sample supplied by a conveying device (described later). wafer) M and a control (here, a double-sided polished floating zone silicon wafer) R, and a polarizer 13 for imparting light transmission characteristics of the sample M to the transmitted light of parallel polarized light. , 8) and the light transmission characteristics of the control R. In this case, the transmitted light of parallel polarized light is strong. ) and a pressure detector 14 connected to the detector 14 to detect the light transmission characteristics of the sample M (i.e., the transmitted light is strong) and the light transmission characteristics of the control R (i.e., the transmitted light is strong). After calculating the absorbance characteristic from the calculation device 15 for calculating the interstitial oxygen concentration of the sample M, the interstitial oxygen concentration calculated by the calculation device 15 is compared with the standard Ia (for example, the upper limit reference value and the lower limit reference value). A comparison device 16 is provided for the purpose of If necessary, reflection! 17A and 17B are inserted. Incidentally, a reflecting mirror (not shown) may be inserted between the Michelson interferometer 12 and the polarizer 13, if necessary.

The transport device includes a pushing member 21 for pushing out the sample M and the control R one by one from the transport containers Tz and T+□, respectively.
, a conveyor belt 22 for conveying the sample M and the control R pushed out by the extrusion member 21 one by one from one end to the other end;
The sample M and the reference R are held one by one and transported to the measurement area, and in the measurement area, the sample M and the reference R are rotated by the rotating device 23A and held at the Brewster angle φ with respect to the parallel polarized light, and the interstitial oxygen concentration is measured. After finishing, turn on the rotating device 2 again.
A gripping member 23 for rotating the sample M and the control R to their initial states by 3A and removing them from the measurement area, and a gripping member 23 for receiving the released sample M and the control R removed from the measurement area at one end. Transport container T @ 1 , T @ @T's T placed at the other end
It is also provided with another conveyor belt 24 for conveying to a2. Control R is transport container T1. However, it may be accommodated together with the sample M in the transport container T (at this time, the transport container TIt is removed).

The transport containers T2□T 12°T2CT14 are each
For example, there is a transport container for storing a defective sample M whose interstitial oxygen concentration exceeds the upper limit reference value, and a good sample M whose interstitial oxygen concentration is between the upper limit reference value and the lower limit reference value.
A transport container is prepared as a transport container for accommodating the sample M, a transport container for accommodating the defective sample M whose interstitial oxygen concentration does not reach the lower limit standard value, and a transport container for accommodating the control R. Depending on the result of the comparison by the comparator 16, the sample R is picked up and the control R is moved to the other end of the conveyor belt 24 to be picked up.

Therefore, at the measuring device pressure, the interference light created by the Michelson interferometer 12 from the light given from the light source 11 is made into parallel polarized light by the polarizer 13, and then transferred to the transport containers Tll, Tl! by the transport device. Samples M are pushed out one by one from the
and is incident at a Brewster angle φ, with respect to the reference R.

Since the sample M and the control R absorb and scatter according to their optical properties, the absorbance properties calculated by the calculation device 15 from the detection results by the detector 14 are as follows.
The shape is as shown in FIG.

The calculation device 15 calculates the optical absorption coefficient α of the sample (i.e., the single-sided polished pulled silicon wafer) M as shown in FIG. The oxygen concentration [0,, ] is calculated as follows.

Thereafter, the comparator 16 uses the sample calculated by the calculation device 15 (i.e., the single-sided polished pulled silicon wafer).
The interstitial oxygen concentration [0,c] of M is compared with a reference value (for example, an upper reference value and a lower reference value).

The comparison result of the comparison device 16 is given as well as the transfer device, and the sample M and the control R are transferred to the transfer container T 21T **,
It is used to accommodate T 2s and T H.

two! Furthermore, the structure and operation of a second embodiment of the silicon wafer manufacturing method according to the present invention will be described in detail.

The second embodiment has the following exceptions: In addition to the step of measuring the interstitial oxygen concentration preceding the gettering step, the step of measuring the interstitial oxygen concentration is performed after the gettering step.
It has the same configuration as the first embodiment.

The interstitial oxygen concentration measurement step that follows the gettering step has the same configuration as the interstitial oxygen concentration measurement step that precedes the gettering step, that is, the measurement step of the first embodiment.

Therefore, since the second embodiment can be easily understood by referring to the first embodiment described above, further explanation will be omitted here.

Yu! In addition, the structure and operation of a third embodiment of the silicon wafer manufacturing method according to the present invention will be described in detail.

In the third embodiment, instead of the interstitial oxygen concentration measurement step preceding the gettering step, the interstitial oxygen concentration measurement step is performed after the gettering step.
It has the same configuration as the first embodiment.

The interstitial oxygen concentration measurement step subsequent to the gettering step has the same configuration as the measurement step of the first embodiment.

Therefore, since the third embodiment can be easily understood by referring to the first embodiment described above, further explanation will be omitted here.

In addition, for the purpose of promoting understanding of the silicon wafer manufacturing method according to the present invention, specific numerical values will be given and explained. Here, for convenience, the case of the above-mentioned first embodiment will be described.

First, the pulled silicon wafer has only one surface mirror-finished (that is, the state of a single-sided polished pulled silicon wafer), and the interstitial oxygen concentration [0, c] was measured (see Table 1).

Thereafter, the back surface of the pulled silicon wafer is mirror-finished, and in this state (that is, the state of a double-sided polished pulled silicon wafer), the interstitial oxygen concentration [0, e] is measured according to the manufacturing method according to the present invention. (See Table 1).

The interstitial oxygen concentration [0°1] measured for single-sided polished pulled silicon wafers and the interstitial oxygen concentration [0, e] − measured for double-sided polished pulled silicon wafers are plotted on the vertical axis Y and the horizontal axis X, respectively. When plotted on the graph shown in FIG. 4, it was found that they were on the straight line Y=X and were in good agreement.

1''-1 Thereby, according to the present invention, the interstitial oxygen concentration of the pulled silicon wafer [0,, It has been found that 1 can be measured directly in the production line.

Although the above explanation has been made only for the case where the Michelson interferometer 12 is used, the present invention is not limited to this, and the present invention is also applicable to the case where a spectrometer is used instead of the Michelson interferometer. It also includes.

In addition, although the case where the step of measuring the interstitial oxygen concentration is performed before and after the gettering step subsequent to the mirror polishing step has been described, the present invention is not limited thereto; It also covers the case where the measurement process is performed at another desired location following the mirror polishing process (for example, in the final inspection process immediately before shipment of a silicon wafer).

(3) Effects of the Invention As is clear from the above, the method for manufacturing a silicon wafer according to the present invention uses a pulled silicon wafer whose surface has been mirror-polished by a mirror-polishing process, as disclosed in the above-mentioned [Means for solving problems]. The interstitial oxygen concentration of the pulled silicon wafer is calculated from the optical transmission characteristics of the silicon wafer and the optical transmission characteristics of the floating zone silicon wafer whose front and back surfaces are mirror-polished and compared with a reference value to determine if the interstitial oxygen concentration is defective. Since the pulled silicon wafer is not used, (i) the floating zone silicon wafer whose front and back surfaces are mirror-polished can be used as a mirror surface without roughening the back surface, and (ii) ) It has the effect of simplifying the measurement work of the interstitial oxygen concentration of pulled silicon wafers, and thereby (iii) it is possible to measure the interstitial oxygen concentration of pulled silicon wafers at a desired location in the production line by 100% inspection. As a result, it has the effect of improving the productivity of the IVL production line.

[Brief explanation of the drawing]

FIG. 1 is a simplified configuration diagram showing a manufacturing apparatus for carrying out a first embodiment of the silicon wafer manufacturing method according to the present invention, and FIG. 2 is a first embodiment of the silicon wafer manufacturing method according to the present invention. 3 and 4 are explanatory diagrams for explaining an embodiment of the silicon wafer manufacturing method according to the present invention. 10・・・・・・・・・・・・Measuring device 11・
・・・・・・・・・・・・Light source 12・・・・・・・・・
...Michelson interferometer 12A...
...Semi-transparent mirror 12B...Movable mirror 12c...Fixed mirror 13...Polarizer 14. ...
・・・・・・・・・Detector 15・・・・・・・・・・
...Calculation device 16...Comparison device 17A, 17B...Reflector 20.
.........Transfer device 21...
......Extrusion member 22...
・・・・・・Transport belt 23・・・・・・・・・・・・・・・
・Gripping member 23A...Rotating device

Claims (1)

[Claims] A method for manufacturing a silicon wafer, in which a pulled silicon wafer is created by subjecting a wafer cut from a pulled silicon single crystal to a series of processing steps including a mirror polishing step, comprising: (a) a first step of measuring the light transmission characteristics of the pulled silicon wafer by making parallel polarized light incident at the Brewster angle on the pulled silicon wafer whose surface has been mirror-polished by a mirror polishing process; (b) front and back surfaces; (c) measuring the light transmission properties of the floating zone silicon wafer by making parallel polarized light incident at Brewster's angle on a reference floating zone silicon wafer that is mirror polished on both sides; A third step for calculating the interstitial oxygen concentration of the pulled silicon wafer from the light transmission characteristics of the pulled silicon wafer measured by the step and the light transmission characteristics of the floating zone silicon wafer measured by the second step. (d) a fourth step for comparing the interstitial oxygen concentration of the pulled silicon wafer calculated in the third step with a reference value; (e) a result of the comparison in the fourth step; and a fifth step of eliminating pulled silicon wafers with poor interstitial oxygen concentration.