WO2017134925A1

WO2017134925A1 - Manufacturing method of wafer and wafer

Info

Publication number: WO2017134925A1
Application number: PCT/JP2016/086455
Authority: WO
Inventors: 田中　利幸; 友裕橋井; 中島　亮
Original assignee: 株式会社Sumco
Priority date: 2016-02-03
Filing date: 2016-12-07
Publication date: 2017-08-10
Also published as: JP2017139323A; JP6500796B2; CN108885981B; CN108885981A; TW201740449A

Abstract

Included are a resin layer forming step for forming a resin layer (R) on one surface (W1) of a wafer (W); a first surface grinding step in which the one surface (W1) is held and another surface (W2) is subjected to surface grinding with the resin layer (R) interposed between; a resin layer removal step for removing the resin layer (R); and a second surface grinding step in which the other surface (W2) is held, and the one surface (W1) is subjected to surface grinding. In the resin layer forming step, the resin layer (R) is formed so as to satisfy formula (1) below. T/X > 30 (1) (where X is the maximum amplitude of undulations for which the wavelength with the wafer is 10–100 mm inclusive, and T is the thickness of the thickest part of the resin layer)

Description

Wafer manufacturing method and wafer

The present invention relates to a wafer manufacturing method and a wafer.

Conventionally, the following is known as a technique for planarizing a wavy wafer.
First, a curable resin is applied to one surface of the wafer, and the curable resin is processed flat and cured. Then, hold the flat surface of the curable resin and grind the other surface of the wafer, hold the other flat surface after removing the curable resin or without removing the one surface of the wafer Grind. Hereinafter, the technique may be referred to as “resin pasting”.

Further, further flattening using such resin pasting grinding has been studied (see, for example, Patent Documents 1 to 4).
Patent Document 1 discloses that a curable resin having a thickness of 40 μm or more and less than 300 μm is applied.
Patent Document 2 discloses that a curable resin having specific characteristics is applied in a thickness of 10 μm to 200 μm.
In Patent Document 3, one surface of a wafer is sucked and held to correct waviness of the wafer, and after grinding the other surface, the other surface is sucked and held to grind one surface. It is disclosed that an equivalent grinding distortion is formed, and thereafter resin pasting is performed.
Patent Document 4 discloses that resin pasting grinding is repeatedly performed.

JP 2006-269976 A JP 2009-272557 A JP 2011-249652 A Japanese Patent Laying-Open No. 2015-8247

By the way, in the semiconductor device manufacturing process, multiple layers of metal and insulating films are formed on the wafer. Since the film thickness uniformity of each layer formed on the wafer affects the device performance, planarization is performed by CMP (Chemical Mechanical Polishing) immediately after the formation of each layer. However, if the wafer has waviness, the accuracy of CMP decreases and a layer with a non-uniform film thickness is formed. In particular, waviness with a wavelength of 10 mm or more and 100 mm or less greatly affects the accuracy of CMP.

However, in the methods as described in Patent Documents 1 to 3, since the grinding is performed without taking into consideration the size of the waviness of the wafer, if the waviness is large, there is a possibility that the surface cannot be sufficiently flattened. For this reason, waviness cannot be made sufficiently small, and there is a possibility that a semiconductor device cannot be manufactured appropriately.
Moreover, in a method like patent document 4, since resin pasting grinding is performed in multiple times, there exists a possibility that manufacturing efficiency may fall.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer manufacturing method and a wafer that can be flattened without lowering the manufacturing efficiency and without affecting the manufacturing of semiconductor devices even when the waviness of the wafer is large. .

The method for producing a wafer according to the present invention includes a resin layer forming step of forming a resin layer by applying a curable resin to one surface of a wafer cut from a single crystal ingot or a lapped wafer, and through the resin layer. The first surface grinding step of holding the one surface and surface grinding the other surface of the wafer, the resin layer removing step of removing the resin layer, holding the other surface, Including a second surface grinding step of surface grinding the surface, wherein the resin layer forming step forms the resin layer so as to satisfy the following formula (1).
T / X> 30 (1)
X: Maximum amplitude of waviness with a wavelength of 10 mm to 100 mm in the wafer T: Thickness of the thickest part in the resin layer

According to the present invention, even on a wafer having a large undulation of a wavelength (10 mm or more and 100 mm or less) that affects semiconductor device manufacture, the undulation of one surface is caused by the resin layer having a thickness based on the above formula (1). Can absorb enough. Therefore, by holding one surface via the resin layer that sufficiently absorbs this undulation, the other surface can be made a flat surface from which the undulation has been sufficiently removed in the first surface grinding step. Further, by holding the other surface from which the undulation is sufficiently removed and subjecting one surface to surface grinding, it is possible to obtain a flat surface from which the undulation of the one surface is sufficiently removed. Furthermore, since it is only necessary to perform the resin pasting grinding only once, the production efficiency is not lowered.
Therefore, even when the waviness of the wafer is large, it is possible to provide a method for manufacturing a wafer that can be planarized without reducing the manufacturing efficiency and without affecting the manufacturing of semiconductor devices.

In the wafer manufacturing method of the present invention, it is preferable that the resin layer forming step forms the resin layer so as to satisfy the following formula (2).
T / X <230 (2)

Here, when the resin layer is too thick and does not satisfy the above formula (2), the resin layer is elastically deformed during the first surface grinding process, and the swell of the other surface may not be sufficiently removed. . Further, even in the second surface grinding step performed by holding the other surface from which the undulation has not been sufficiently removed, there is a possibility that the undulation of the one surface cannot be sufficiently removed.
According to the present invention, since the resin layer having an appropriate thickness is formed so as to satisfy the above formula (2), it is possible to suppress the resin layer from being elastically deformed during the first surface grinding process, The surface can be a flat surface from which the undulation has been sufficiently removed. Further, in the subsequent second surface grinding step, one surface can be made a flat surface from which the undulation is sufficiently removed. Therefore, a wafer with high flatness can be obtained with certainty.

The wafer of the present invention is characterized in that the amplitude of the undulation having a wavelength of 10 mm or more and 100 mm or less is less than 0.5 μm.

According to the present invention, since the amplitude of the waviness of the wavelength affecting semiconductor device manufacturing is less than 0.5 μm, it is possible to provide a wafer that does not affect semiconductor device manufacturing.

The wafer of the present invention has a maximum surface shape of 1.2 nm / mm ² or less at a 10 mm × 10 mm site when the surface shape is measured in the high order shape mode of the flatness measuring device Wafersight 2 (manufactured by KLA-Tencor). It is characterized by being.

Here, “Shape Curve” is an index representing the warpage of a wafer, and the curvature of an approximate surface approximated by a quadratic order with respect to a surface divided into a designated site size (in the present invention, 10 mm × 10 mm). To express. For this reason, the larger the shape curvature, the greater the waviness of the wafer.
According to the present invention, since the maximum value of Shape Curve at a 10 mm × 10 mm site is 1.2 nm / mm ² or less, a wafer capable of appropriately manufacturing a semiconductor device can be provided.

The flowchart of the manufacturing method of the wafer which concerns on one Embodiment of this invention. Explanatory drawing of the manufacturing method of the said wafer. Explanatory drawing of the manufacturing method of the said wafer. Explanatory drawing of the manufacturing method of the said wafer. Explanatory drawing of the manufacturing method of the said wafer. Explanatory drawing of the manufacturing method of the said wafer. Explanatory drawing of the manufacturing method of the said wafer. The graph which shows the relationship between the manufacturing method of the wafer in the Example of this invention, and Shape Curvature. The graph which shows the relationship between the manufacturing method of the wafer in the said Example, and the maximum amplitude of the wave | undulation whose wavelength is 10 mm or more and 100 mm or less. The graph which shows the relationship between T / X and Shape Curve in the said Example.

An embodiment of the present invention will be described with reference to the drawings.
[Wafer manufacturing method]
As shown in FIG. 1, in the wafer manufacturing method, first, a single crystal ingot (hereinafter simply referred to as “ingot”) such as silicon, SiC, GaAs, or sapphire is cut with a wire saw to obtain a plurality of wafers ( Step S1: Slicing step).
Next, both surfaces of the wafer are simultaneously planarized by a lapping apparatus (step S2: lapping process) and chamfered (step S3: chamfering process).
At this time, since it is difficult to achieve sufficient planarization of the wafer only by the lapping process, the wafer W in which the undulations W11 and W21 are generated on one surface W1 and the other surface W2, as shown in FIG. can get.
Thereafter, as shown in FIG. 1, a resin layer forming step (step S4) in which a curable resin is applied to one surface W1 of the wafer W to form a resin layer R (see FIG. 2B); A first surface grinding step (step S5) for holding one surface W1 and surface grinding the other surface W2 of the wafer W, a resin layer removing step (step S6) for removing the resin layer R, and the other A second surface grinding step (step S7) for holding the surface W2 and surface grinding one surface W1 is performed.

In the resin layer forming step, first, the surface shapes of one surface W1 and the other surface W2 are measured, and the maximum amplitude X of the undulation W11 having a wavelength of 10 mm to 100 mm and the in-plane thickness variation of the wafer W (TTV). : Total Thickness Variation) V. Since the swell W11 and the swell W21 are substantially symmetrical, their maximum amplitudes are almost the same.
Next, the thickness of the resin layer R that satisfies the following formula (1) is obtained.
T / X> 30 (1)
T: Thickness of the thickest part in the resin layer R At this time, it is preferable that the thickness of the resin layer R satisfies the following formula (2).
T / X <230 (2)

Moreover, based on the following formula | equation (3), the machining allowance minimum value P of the other surface W2 in the 1st, 2nd surface grinding process and one surface W1 is calculated | required.
P = X + V (3)
Note that the maximum amplitude X and the in-plane thickness variation V may be used as long as they can be estimated from the ingot slicing conditions and the measurement results of the wafers W in the same lot.

Next, the resin layer R is formed using the holding press apparatus 10 as shown to FIG. 2B.
First, a curable resin to be the resin layer R is dropped on the highly flattened flat plate 11. On the other hand, as shown by a solid line in FIG. 2B, the holding means 12 sucks and holds the other surface W2 of the wafer W by the holding surface 121.
Next, the holding means 12 is lowered, and one surface W1 of the wafer W is pressed against the curable resin as indicated by a two-dot chain line in FIG. 2B. Thereafter, the pressure applied to the wafer W by the holding means 12 is released, and the curable resin is cured on the one surface W1 without causing the wafer W to be elastically deformed. Through the above steps, the surface opposite to the surface in contact with one surface W1 becomes the flat surface R1, and the resin layer R in which the thickness of the thickest portion satisfies the above formulas (1) and (2) is obtained. It is formed.

In addition, as a method of applying the curable resin to the wafer W, the curable resin is dropped by dropping the curable resin on one surface W1 with the one surface W1 facing upward, and rotating the wafer W. One side by spin coating method that spreads resin over one side W1, the screen printing method by placing a screen plate on one side W1, placing a curable resin on the screen plate, and applying with a squeegee, electric spray deposition method A method of pressing the flattened flat plate 11 against the curable resin after applying the curable resin by a method such as spraying on the entire surface of W1 can be applied. The curable resin is preferably a curable resin such as a thermosetting resin, a thermoreversible resin, or a photosensitive resin in terms of ease of peeling after processing. In particular, the photosensitive resin is also preferable in that stress due to heat is not applied. In the present embodiment, a UV curable resin is used as the curable resin. Other specific curable resin materials include synthetic rubber and adhesives (wax, etc.).

In the first surface grinding step, the other surface W2 is surface ground using a surface grinding device 20 as shown in FIG. 2C.
First, when the wafer W is placed on the highly flattened holding surface 211 of the vacuum chuck table 21 with the flat surface R1 facing downward, the vacuum chuck table 21 sucks and holds the wafer W.
Next, as shown by a solid line in FIG. 2C, the surface plate 23 provided with the grindstone 22 on the lower surface is moved above the wafer W. Then, while rotating the surface plate 23, the vacuum chuck table 21 is rotated, and as shown by a two-dot chain line in FIG. 2C, the grindstone 22 and the other surface W2 are brought into contact with each other. Surface grinding. When the machining allowance is equal to or greater than the machining allowance minimum value P, the surface grinding is finished. By the above process, the other surface W2 becomes a flat surface from which the undulation is sufficiently removed.

In the resin layer removing step, the resin layer R formed on one surface W1 of the wafer W is peeled off from the wafer W as shown in FIG. 3A. At this time, the resin layer R may be removed chemically using a solvent.

In the second surface grinding step, as shown in FIG. 3B, one surface W1 is surface ground using the same surface grinding device 20 as in the first surface grinding step.
First, when the wafer W is placed on the holding surface 211 with the other flat surface W2 facing down, the vacuum chuck table 21 sucks and holds the wafer W, as shown by a solid line in FIG. 3B. In addition, the surface plate 23 moved above the wafer W is lowered while being rotated, and the vacuum chuck table 21 is rotated, so that one surface W1 is surface ground as indicated by a two-dot chain line in FIG. 3B. When the machining allowance is equal to or greater than the machining allowance minimum value P, the surface grinding is finished, so that one surface W1 becomes a flat surface from which the undulation is sufficiently removed.

Through the above resin pasting and grinding process, the undulations W11 and W21 are sufficiently removed, and as shown in FIG. 3C, a wafer W in which one surface W1 and the other surface W2 are highly planarized is obtained.
The obtained wafer W has a wave amplitude of less than 0.5 μm with a wavelength of 10 mm or more and 100 mm or less, and when measured in the High Order Shape mode of the flatness measuring device Wafersight 2, a Shape at a 10 mm × 10 mm site is used. The maximum value of Curve (hereinafter simply referred to as “Shape Curve”) is 1.2 nm / mm ² or less.

Next, as shown in FIG. 1, etching is performed in order to remove a work-affected layer that occurs during chamfering or resin pasting grinding and remains on the wafer W (step S8: etching process).
Thereafter, mirror polishing including a primary polishing step (step S9) for polishing both surfaces of the wafer W using a double-side polishing device and a final polishing step (step S10) for polishing both surfaces of the wafer W using a single-side polishing device. A process is performed and the manufacturing method of a wafer is complete | finished.

[Effects of Embodiment]
As described above, since the resin bonding grinding process is performed using the resin layer R having a thickness that takes into account the amplitude of the waviness W11 of the wafer W based on the above formula (1), one surface W1 and the other surface The undulations W11 and W21 on the surface W2 can be sufficiently removed. Furthermore, since the resin pasting and grinding process needs to be performed only once, the production efficiency does not decrease. Therefore, even when the waviness of the wafer W is large, it is possible to provide a method for manufacturing the wafer W that can be planarized without reducing the manufacturing efficiency and without affecting the manufacturing of the semiconductor device.
In particular, since the thickness of the resin layer R is set so as to satisfy the above formula (2), a wafer W with high flatness can be obtained with certainty.

[Modification]
It should be noted that the present invention is not limited to the above-described embodiment, and various improvements and design changes can be made without departing from the scope of the present invention. The general procedure and structure may be other structures as long as the object of the present invention can be achieved.

For example, you may perform a resin sticking grinding process on the conditions which satisfy | fill the said Formula (1) at least, without performing a lapping process. Even in such a case, the wafer W having the above-described characteristics can be obtained.
Further, the resin layer R may be removed by grinding in the second surface grinding step as the resin layer removing step, instead of peeling off.

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[Relationship between Wafer Manufacturing Method, Shape Curvature, and Maximum Amplitude of Waviness with Wavelength of 10 mm to 100 mm]
[Wafer manufacturing method]
{Example 1}
First, the slicing step shown in FIG. 1 was performed to prepare a wafer having a diameter of 300 mm and a thickness of about 900 μm. Next, a lapping process and a chamfering process were performed on these wafers. In the lapping step, lapping was performed with slurry containing alumina abrasive grains without using a polishing cloth, using a lapping apparatus (HAMAI32BN) manufactured by Hamai Sangyo Co., Ltd.
Then, using a wafer flatness / shape measuring instrument (SBW) manufactured by Kobelco Kaken Co., Ltd., the shape of one surface of the wafer is measured and frequency analysis is performed, so that the wavelength after the lapping process is 10 mm or more and 100 mm. The maximum amplitude X of the following swell was determined. As shown in Table 1, the maximum amplitude X was 0.9 μm.

Then, the resin pasting grinding process was performed. In the resin layer forming step, a resin layer was formed by applying a UV curable resin and curing it by UV irradiation. As shown in Table 1, the thickness T of the thickest part of the resin layer was 80 μm, and T / X was 88.9 satisfying the above formula (1). In addition, thickness T measured the thickness of the wafer before resin pasting, and the total thickness of the wafer after resin pasting, and resin using the linear gauge (LGF) by Mitutoyo Corporation, from these differences Asked.
And the 1st surface grinding process, the resin layer removal process, and the 2nd surface grinding process were performed. In the first and second surface grinding steps, surface grinding was performed using a disco grinding machine (DFG8360) with a machining allowance of 20 μm.
Then, the etching process to the mirror polishing process was performed.

{Example 2}
First, a slicing process was performed to prepare a wafer having a diameter of 300 mm and a thickness of about 900 μm. As shown in Table 1, the maximum amplitude X of the undulation having a wavelength of 10 mm or more and 100 mm or less after the slicing step was 1.5 μm.
Then, without performing the lapping step, as shown in Table 1, under the same conditions as in Example 1 except that a resin layer having T / X of 53.3 satisfying the above formula (1) was formed. The process from the resin pasting grinding process to the mirror polishing process was performed.

{Comparative Example 1}
As shown in Table 1, from the slicing step to the mirror polishing step under the same conditions as in Example 1 except that a resin layer having a T / X of 27.8 that does not satisfy the above formula (1) is formed. Went.

{Comparative Example 2}
As shown in Table 1, Example 1 is the same as Example 1 except that only the first and second surface grinding steps of the resin pasting grinding step are performed instead of the resin pasting grinding step. From the slicing process to the mirror polishing process were performed under the same conditions. The machining allowance in the first and second surface grinding steps was 20 μm.

[Evaluation]
Four wafers were processed and evaluated under the conditions of Examples 1 and 2 and Comparative Examples 1 and 2, respectively.

{Shape Curve}
The surface shape of each wafer was measured in the High Order Shape mode of the flatness measuring device Wafersight 2 (manufactured by KLA-Tencor), and the maximum value of Shape Curve was evaluated. The evaluation results are shown in FIG.
As shown in FIG. 4, in Examples 1 and 2 where T / X satisfies the above formula (1), both were 1.2 nm / mm ² or less, and the smaller T / X, the smaller the value. On the other hand, T / X exceeded 1.2 nm / mm ² in Comparative Example 1 in which the above formula (1) was not satisfied and in Comparative Example 2 in which the resin pasting grinding step was not performed.

{Maximum amplitude of waviness with a wavelength of 10 mm to 100 mm}
The maximum amplitude of undulation with a wavelength of 10 mm or more and 100 mm or less was obtained and evaluated in the same manner as when the maximum amplitude X of undulation after the lapping step in Example 1 was obtained. The evaluation results are shown in FIG.
As shown in FIG. 5, in Examples 1 and 2 where T / X satisfies the above formula (1), both were less than 0.5 μm, and the smaller T / X, the smaller the value. On the other hand, in Comparative Example 1 where T / X does not satisfy the above formula (1) and in Comparative Example 2 where the resin pasting grinding step is not performed, both exceeded 0.5 μm.

{Summary}
From the above, by performing the resin bonding grinding process under the condition that T / X satisfies the above formula (1), whether it is a wafer that has been performed from the slicing process to the lapping process or a wafer that does not perform the lapping process, It was confirmed that a wafer with high manufacturing efficiency and flatness and capable of appropriately manufacturing a semiconductor device can be provided.
In this example, the wafer after the mirror polishing process was evaluated. However, the shape immediately after the resin bonding grinding process (in Comparative Example 2, the first and second surface grinding processes) is also shown in FIGS. It can be estimated that The reason is that the machining allowance in the etching process and the mirror polishing process is very small compared to the lapping process and the resin bonding grinding process, so the flatness after the mirror polishing process is almost equal to the flatness immediately after the resin bonding grinding process. Because.

[Examination of allowable range of T / X]
Except that the thickness of the resin layer was changed at a plurality of levels, the same processing as in Example 1 was performed on two wafers at each level, and the maximum value of Shape Curvature was evaluated. The evaluation results are shown in FIG.
As shown in FIG. 6, it was confirmed that when T / X was more than 30 and less than 230, it was 1.2 nm / mm ² or less.

R ... resin layer, W ... wafer, W1 ... one side, W2 ... the other side.

Claims

A resin layer forming step of forming a resin layer by applying a curable resin to one surface of a wafer cut from a single crystal ingot or a lapped wafer;
A first surface grinding step of holding the one surface via the resin layer and surface grinding the other surface of the wafer;
A resin layer removing step of removing the resin layer;
A second surface grinding step of holding the other surface and surface grinding the one surface;
In the resin layer forming step, the resin layer is formed so as to satisfy the following formula (1).
T / X> 30 (1)
X: Maximum amplitude of waviness with a wavelength of 10 mm to 100 mm in the wafer T: Thickness of the thickest part in the resin layer
In the manufacturing method of the wafer according to claim 1,
The said resin layer formation process forms the said resin layer so that the following formula | equation (2) may be satisfy | filled, The manufacturing method of the wafer characterized by the above-mentioned.
T / X <230 (2)
A wafer characterized in that the amplitude of undulations having a wavelength of 10 mm or more and 100 mm or less is less than 0.5 μm.
When the surface shape is measured in the High Order Shape mode of the flatness measuring device Wafersight 2 (manufactured by KLA-Tencor), the maximum value of the Shape Curve at a 10 mm × 10 mm site is 1.2 nm / mm 2 or less. Wafer to be used.