JPS61214515A - Susceptor for semiconductor substrate - Google Patents

Abstract

PURPOSE:To suppress the infiltration of impurity contamination into a substrate while a growing method is performed by a method wherein a circular recessed part is provided on the surface of the susceptor which retains a semiconductor substrate on which a vapor-phase growing method is going to be performed, said recessed part is filled up with an amorphous material having the coefficient of thermal expansion smaller than that of the substrate, the substrate is placed thereon, and a vapor-phase growing method is performed. CONSTITUTION:A circular recessed part 32 is provided on the surface of the susceptor main body 31 consisting of high purity graphite whereon SiC is coated, the recessed part is filled up with the SiO2 having the coefficient of thermal expansion smaller than that of the Si substrate 34 which is grown on the recessed part 32, and it is used as a substrate retaining stand 33. No impurities are infiltrated into the substrate 34 and no etching pit and the like are generated while a growing method is performed, if the susceptor is constituted as above, an Si substrate 34 is placed on the retaining stand 33, they are placed in a vapor-phase growing device and an epitaxial growing method is performed. SiO2 is used for the retaining stand 33, but Si3N4 may be used instead of the SiO2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a susceptor for semiconductor substrates mainly used for vapor phase growth.

[Technical background of the invention and its problems]

Traditionally, silicon vapor phase growth technology has occupied an important position in the semiconductor industry. % bipolar IC requires a special structure to increase the operating speed, and silicon vapor phase growth technology is an essential technology. In addition, in recent years MO
In the field of 8LSI, epitaxial wafers using silicon vapor phase growth technology are being used as the integration and density increases, and silicon epitaxial wafers are indispensable for MO8LSI in response to the design rule of 1.2 μm or less. It is said. Thus, silicon vapor phase technology has been gaining importance in recent years. By the way, conventionally, as a vapor phase growth apparatus for silicon epitaxial growth for bipolar LSI and MO8LSI, a vertical type as shown in FIG. 2 or a cylindrical type as shown in FIG. 5 are known.

In FIG. 2, reference numeral 1 denotes a reaction tube made of synthetic quartz and having a rotating shaft 2 at the center of its lower part. A semiconductor substrate susceptor 3 is provided above the rotating shaft 2, and a plurality of semiconductor substrates 4 are set on the susceptor 3. Incidentally, the aforementioned segmenter 3 is rotated by the rotating shaft 2. The center of the rotating shaft 2 and the susceptor 3 is hollow, and a reaction gas introduction pipe 5 is provided in the hollow. This reaction gas outlet 6
is provided. A high-frequency heating coil 7 is provided below the susceptor 3 and around the rotating shaft 2 . A reaction gas exhaust pipe 8 is provided at the bottom of the reaction tube 2 .

In FIG. 3, 11 is a reaction tube made of synthetic quartz.

A semiconductor substrate susceptor 13 having a shape penetrated by a rotating shaft 12 is provided inside the reaction tube 11 . A plurality of semiconductor substrates 14 are provided on the side surface of this susceptor 13. A reaction gas introduction pipe 15 is provided at the top of the reaction tube 11, and a reaction gas discharge pipe 16 is provided at the bottom of the reaction tube 11. A plurality of halogen lamps 17 are provided on the peripheral side of the reaction tube 11, and a reflecting mirror 18 is provided on the outside of the halogen lamps 17. Also, around the reaction tube 11 there is cooling water, etc.
. is provided, and the semiconductor substrate 14 is treated with halogen 2.
It is designed to heat up intensively with ng 17....

In the above-mentioned vapor phase growth apparatus, a partially enlarged view of the susceptor for a semiconductor substrate is shown in FIG. 21 in the figure is a susceptor body. This susceptor body 21 is provided with a recess 23 slightly larger than the substrate 22 for setting the semiconductor substrate 22 therein. Here, the semiconductor substrate 22 is set with its back surface in contact with the recess 23 of the susceptor body 21.

By the way, BSD (Back Side Dam) has conventionally been used as a countermeasure against impurity contamination during epitaxial growth.
The doutering method is used by et al.

This is an attempt to generate dislocations near the back surface of a semiconductor substrate and capture impurities by spraying an abrasive or the like on the back surface of the semiconductor substrate to cause scratches. However, the BSD method has problems such as ineffectiveness in process steps before epitaxial growth, cracks occurring on the back surface of the substrate when scratching the substrate, and fine particles entering the cracks to cause scratches.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a susceptor for a semiconductor substrate that can suppress impurity contamination during vapor phase growth from entering an active region in the semiconductor substrate by applying elastic strain to the semiconductor substrate. The purpose is to

[Summary of the invention]

The present invention is capable of suppressing impurity contamination during vapor phase growth from entering the active region of the semiconductor substrate by providing a substrate support that applies elastic strain to the semiconductor substrate on the upper part of the susceptor body. .

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 and 5.

Embodiment 1 In FIG. 1, numeral 31 is a susceptor body made of, for example, high-purity graphite coated with SIC. A circular recess 32 is provided in the upper part of the susceptor main body 3. This recess 32 is provided with a substrate support 33 having a slightly smaller diameter. This board support stand 33
For example, the silicon substrate 3 set on the support stand 33
Amorphous silicon dioxide (st
o2).

Therefore, according to the present invention, the recess 3 of the susceptor body 31
2, an amorphous material 5 having a smaller coefficient of thermal expansion than the silicon substrate 34;
Since the structure includes a substrate support 33 made of tO2, when silicon epitaxial growth is performed using a vertical vapor phase growth apparatus, elastic strain occurs on the back surface of the substrate 34 due to thermal expansion, and this causes vapor phase growth. It can capture impurity contamination inside.

Next, using the susceptor for semiconductor substrates of the above example, silicon unioxide was grown in a vapor phase using a vertical vapor phase growth apparatus. At this time, Silicon Unino is P type (100) with a specific resistance of 1Ω.
・It is a bell. Further, vapor phase growth was performed using 5IH2Ct2 at 1200 DEG C. for 15 minutes to obtain a silicon epitaxial wafer having an epitaxial layer with a thickness of 10 .mu.m. As a comparative example, a silicon epitaxial wafer was formed using a conventional susceptor for semiconductor substrates (FIG. 4) under the same conditions as above. When these wafers were subjected to light etching for 90 seconds and the wafer surfaces were observed using a differential interference microscope, a large number of etched bits were observed on the wafers of the comparative example, but none were observed on the wafers of the example.

Also, are there any MOS capacitors on these wafers? Make a jitter D
LTS method (D@ep Level Transitio
When impurities in the epitaxial layer were analyzed using a method using a method of analyzing impurities in the epitaxial layer, Ni and F were detected in the comparative example, but nothing was detected in the example. From the above, it is clear that the susceptor for semiconductor substrates of the present invention is superior to conventional susceptors.

In the above embodiment, the material of the substrate support is amorphous 51.
02, but the material is not limited to this, and silicon nitride (Sl, N4) may be used.

Embodiment 2 In FIG. 5, 41 indicates the recess 32 of the susceptor body 41.
It is a member made of silicon single crystal having the same coefficient of thermal expansion as the silicon substrate 34 provided on the substrate. The opening at the top of this member 41 has a larger coefficient of thermal expansion than the substrate 34 .

For example, an annular member 42 made of aluminum oxide (At20.) is provided. Here, the member 41°4
The two parts are collectively called a substrate support stand 43.

Therefore, in the semiconductor substrate susceptor shown in FIG. 5, since the member 41 having a larger coefficient of thermal expansion than the substrate 3.4 expands relatively during vapor phase growth, elastic strain occurs on the back surface of the substrate 34.
The same effects as in Example 1 can be obtained.

In the second embodiment, a case has been described in which the member 41 is made of silicon single crystal, but is not limited to this.
102. A material having a small coefficient of thermal expansion for the silicon substrate 34, such as S1 or N4, may be used.

Further, in the second embodiment, the case where the member 42 is made of At203 has been described, but the material is not limited to this, and may be made of quartz, silicon carbide (SiC), or the like.

〔Effect of the invention〕

As detailed above, according to the present invention, it is an object of the present invention to provide a highly reliable susceptor for a semiconductor substrate that can suppress impurity contamination during vapor phase growth from penetrating into the semiconductor substrate.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a susceptor for semiconductor substrates according to an embodiment of the present invention, FIG. 2 is a sectional view of a vertical type vapor phase growth apparatus for silicon epitaxial growth, and FIG. 3 is a sectional view of a cylindrical type vapor phase growth apparatus for silicon epitaxial growth. FIG. 4 is a cross-sectional view of a conventional susceptor for semiconductor substrates, and FIG. 5 is a cross-sectional view of a susceptor for semiconductor substrates according to another embodiment of the present invention. 1.11...Reaction tube, 1,12... Rotating shaft, 5゜1
5... Reactive gas introduction pipe, 6... Reactive gas outlet, 7
... High frequency heating coil, 8.16... Reaction gas discharge pipe, 11... Reaction tube, 17... Halodan lamp,
18...Reflector, 19...Cooling water, 31...Susceptor main body, 33.43...Substrate support stand, 34...Silicon substrate. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 1 312 Figure 3 Figure 4 η Figure 5

Claims (5)

[Claims] (1) A susceptor for a semiconductor substrate used in vapor phase growth of a semiconductor substrate is characterized by comprising a susceptor body and a substrate support that is provided on the top of the susceptor body and applies elastic strain to the semiconductor substrate. Susceptor for semiconductor substrates. (2) The susceptor for a semiconductor substrate according to claim 1, wherein the substrate support is made of a material having a coefficient of thermal expansion smaller than that of the semiconductor substrate. (3) The substrate support includes a first member made of a material having a coefficient of thermal expansion larger than that of the substrate, which is provided in close contact with the semiconductor substrate in an annular shape, and a back surface of each of the first member and the substrate, and 2. The susceptor for a semiconductor substrate according to claim 1, further comprising a second member made of a material having a coefficient of thermal expansion equal to or lower than that of the substrate, which is provided in close contact with a side wall of the member. (4) The susceptor for a semiconductor substrate according to claim 2, wherein a silicon substrate is used as the semiconductor substrate, and the substance with a small coefficient of thermal expansion is aluminum oxide, crystal, or silicon carbide. (5) In addition to using a silicon substrate as the semiconductor substrate, the material with a small coefficient of thermal expansion is aluminum oxide, crystal, or silicon carbide, and the material with a coefficient of thermal expansion equal to or lower than that of the substrate is amorphous silicon dioxide or silicon nitride. A susceptor for a semiconductor substrate according to claim 3, characterized in that: