JPS6097619A - Manufacture of semiconductor - Google Patents

Abstract

PURPOSE:To prevent a minute defect and the generation of warping and contrive to improve yield by determining the inter-lattice oxygen concentration included in a silicon crystal at a specific value. CONSTITUTION:By determining the inter-lattice oxygen concentration in a silicon crystal at 4.5X10<17>-12.0X10<17>atom/cm<3>, a silicon wafer which is difficult in generating a minute defect or a warp by thermal stress can be obtained, while the process can be stabilized and the yield can be improved. If the inter- lattice oxygen concentration in a silicon crystal is less than 4.5X10<17>atom/cm<3>, the crystal is too clean and a surface lamination defect is apt to be generated due to the effect of contamination by a very small amount of metal ion impurity. On the other hand, if the interstitial oxygen concentration is more than 12.0X10<17>atom/cm<3>, a minute defect is apt to be formed during heat treatment and a positioning due to thermal stress is apt to be generated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to semiconductor manufacturing technology, and particularly to a semiconductor manufacturing technology that is effective when applied to manufacturing semiconductor wafers made of silicon (Si).

[Background technology] The mainstream material of semiconductor devices currently used is silicon crystal, and the methods for growing it are the Czochralski method (CZ method, pulling method) and the floating zone method (FZ method, zone melting refining method). There is.

Currently, most wafers used for silicon devices, mainly LSIs, are grown using the C2 method.

Since C2 crystals produced by the C2 method are pulled by melting silicon in a quartz crucible, oxygen atoms eluted from the crucible segregate in the single crystal, and with normal growth techniques ~15 x 10
'atoa+s/d of interstitial oxygen is common.

On the other hand, FZ silicon wafers manufactured using the FZ method (zonal fusion refining method) have an interstitial oxygen concentration that is approximately two orders of magnitude lower than that of CZ wafers (~10 I6atoms/cd), but are susceptible to slipping and warping due to thermal stress during the device process. Because of the tendency for this to occur, it currently has only limited uses, such as in cyrisk elements that require high resistance.

By the way, when the oxygen concentration in the crystal exceeds the solid solubility limit at the heat treatment temperature of the device process, precipitation of supersaturated oxygen occurs. The ease of precipitation depends on the density of microdefect nuclei generated by the thermal history in the furnace during or after crystal growth, and on the oxygen concentration. Oxygen precipitates induce micro defects such as dislocation loops and stacking faults.

Since such minute defects promote the occurrence of thermal stress dislocations, a wafer with a higher defect density is more likely to warp. If the warpage is large, the accuracy of transferring the mask pattern in the photolithography process will be reduced.

On the other hand, the introduced thermal stress dislocations deteriorate device characteristics and cause a decrease in yield. In solid-state imaging devices, the presence of crystal defects causes white spot defects in images, so there is a strong demand for crystals that are less likely to have crystal defects.

In addition, attempts have been made to improve device yield by performing intrinsic gettering, but a crystal suitable for this purpose has an interstitial oxygen concentration of ~15 x 10"a
It is said that it is desirable to have a particle size of about toms/cta.

[Object of the Invention] An object of the present invention is to provide a semiconductor manufacturing technology that is less likely to generate minute defects, less likely to warp due to thermal stress, and capable of improving yield.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, in a semiconductor made of silicon, the interstitial oxygen concentration contained in the silicon crystal is 4.5 × 10" ~ 1
2. By setting OX 10'atoms/ctl, it is possible to manufacture a semiconductor in which micro defects and warpage are less likely to occur, and it is possible to improve the yield.

[Example 1] Generally, there is a close relationship between the interstitial oxygen concentration of a wafer during growth (as-groeyn) and the microdefect density generated by heat treating the wafer.

Therefore, as an example, the present inventors grew single crystals containing different oxygen concentrations, examined the warping caused by thermal stress in the wafers produced from the single crystals, and found a range of interstitial oxygen concentrations contained in the wafers in which warping is less likely to occur. We conducted extensive experimental research.

゛The growth conditions for the silicon single crystal used for this experiment were as shown in Table 1 below.

The sampling positions of these single crystal samples (1), (2), and (2) are shown for each single crystal ingot shown in FIGS. 1 (al, 2) and (C), respectively.

Then, forced heat treatment (
1) The amount of warpage of the wafer was evaluated using (I[).

When the evaluation results of this wafer warp amount were plotted along with the evaluation results of comparison wafers at the position within the single crystal ingot,
The results shown in FIGS. 3 and 4 were obtained. Third
In the figure and FIG. 4, the vertical axis represents the warpage [μm], and the horizontal axis represents the position [CIl] from the shoulder of the single crystal ingot.

- On the other hand, the relationship between the position from the shoulder of the single-crystal ingot and the microdefect density for each sample (1), (2), and (2) was as shown in FIG.

Furthermore, the relationship between the position from the shoulder of the single crystal ingot and the oxygen concentration in each sample (2), (2), and (2) was as shown in FIG.

According to the results in Figure 6, the oxygen concentration is 7.5X1017~
At 12 x 10"atoms/cJ, the warpage due to thermal stress is extremely small. Also, by performing crystal growth in a strong magnetic field, the oxygen concentration is 4.5 x 1
017~? , 5X101 fato+*s/cll, it has been found through research by the present inventors that a good warpage suppressing effect can be obtained.

The converted value of this interstitial oxygen concentration is based on the American standard (A
STM) F121-79, and this converted value is used throughout this specification.

As shown in FIGS. 7 and 8, the amount of wafer warpage strongly depends on the microdefect density, regardless of the forced heat treatment.

In this way, according to this example, the interstitial oxygen concentration of the silicon crystal is increased from 4.5X10'' to 12.OX10''.
By using atoms/cJ, it is possible to obtain a silicon wafer that is less likely to warp due to thermal stress due to the generation of minute defects, thereby making it possible to stabilize the process and improve the yield.

The interstitial oxygen concentration of silicon crystal is 4.5X1017at
oms/cI! If it is lower than , the problem arises that the crystal is too clean and surface stacking defects are likely to occur due to the influence of contamination by minute amounts of metal ion impurities. In that sense, the interstitial oxygen concentration is preferably 7.5
0" to 12.OX 10"atoms/c+a.

On the other hand, the interstitial oxygen concentration of silicon crystal is 12.0X 1
When the value is higher than 0'' atoms/cLa, a problem arises in that micro defects are more likely to be formed during heat treatment and thermal stress dislocations are more likely to occur.

[Effect] (■), the interstitial oxygen concentration of silicon crystal is 4.5X10
"~12. OX 10" atoms/cd makes it possible to obtain a silicon semiconductor that is less likely to generate minute defects in the oxidation diffusion process, etc., and less prone to slip or warp due to thermal stress, thereby improving the yield. can.

(2), the interstitial oxygen concentration is 7.5XI01f~l 2.
If OX 10 '' atoms/- is used, surface stacking defects due to contamination by trace amounts of metal ion impurities are less likely to occur (and a better silicon semiconductor can be obtained).

Although the invention made by the present inventor has been specifically explained above based on examples, it goes without saying that the present invention is not limited to the above-mentioned examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, wafer heat treatment conditions etc. may be selected from conditions other than those described above.

In particular, if the semiconductor manufacturing method according to the present invention is used for solid-state imaging devices, the white spot defect rate can be reduced (and the prologue test yield can also be greatly improved).

In particular, as devices become more highly integrated, wafer warpage has a greater effect on transfer accuracy in the photolithography process, and as the bond size becomes smaller, the effect of microcrystal defects on the characteristics becomes greater. Therefore, the greatest effect can be obtained if the present invention is applied to highly integrated devices or solid-state image sensors.

[Field of Application] In the above explanation, the invention made by the present inventor is mainly applied to highly integrated devices and solid-state image sensors, which are the background fields of application, but the present invention is not limited thereto. , for example, various other MOs
It can be applied to S type or bipolar type devices, and becomes more useful as devices become more highly integrated. Further, the present invention can be applied to Cyrisk and the like.

[Brief explanation of the drawing]

Figures 1 (al, (b), and (C) are diagrams showing the tempering positions of silicon wafers in various single crystal samples, Figure 2 is a diagram showing heat treatment conditions for silicon wafer samples and their warpage evaluation method, and Figure 3 Figure 4 shows the amount of warpage due to heat treatment, Figure 4 shows the amount of warpage due to heat treatment under other conditions, Figure 5 shows the micro defect density at various positions of the single crystal ingot, Figure 6 is the same. FIG. 7 is a diagram showing the relationship between the micro defect density and the amount of warpage. FIG. 8 is a diagram showing the relationship between the micro defect density and the amount of warpage under other heat treatment conditions. ＊Rhyme Ij′2γ卜ツ4i11かの四stand”；11□
(Q skin) Figure 6

Claims (1)

[Claims] 1. In a method for manufacturing a semiconductor made of silicon, the interstitial oxygen concentration contained in the silicon crystal is set to 4.5×10
” ~12.OX 10”atoms/ad. 2. Interstitial oxygen concentration is 7.5X10"~12.OX
10'' atoIIls/cj. The semiconductor manufacturing method according to claim 1.