JP3575567B2 - Semiconductor wafer vapor phase growth deposition method and vertical heat treatment apparatus - Google Patents

Description

【００２０】
【表２】

【００２１】
【発明の効果】
この発明は、縦型熱処理炉において、処理効率の良いＢａｃｋ ｔｏＢａｃｋ法を実現したもので、ボート支柱の溝部のウェーハ支持部領域に下り傾斜面を形成して、実施例に示すようにボートの各棚にウェーハを２枚積載させてかつウェーハを所要角度だけ傾斜させて載置して成膜プロセスすると、熱処理中でのウェーハの落下を防止しかつ下側に移載したウェーハ裏面のボート支柱の溝部内の接触部の膜厚減少も解消でき、縦型熱処理炉での生産性を大幅に向上させることができる。
【図面の簡単な説明】
【図１】Ａはこの発明による縦型熱処理装置用のボート支柱の説明図であり、Ｂは従来のボート支柱の説明図である。
【図２】Ａはこの発明によるボートを用いた気相成長成膜方法を示す説明図であり、Ｂは従来のボートを用いた気相成長成膜方法を示す説明図である。
【図３】この発明によるボートを用いた気相成長成膜方法を示す説明図である。
【符号の説明】
１，１０ ボート支柱
２，１１ 溝部
３ ウェーハ支持領域
５ 半導体ウェーハ
６，１２ ボート[0001]
[Industrial applications]
The present invention relates to a film forming method for vapor-phase growing a polysilicon thin film (PBS) on the back surface of a wafer in order to provide a gettering structure that enables a highly reliable device in a device process, and uses a vertical heat treatment furnace. The present invention relates to a method for vapor-phase growth and deposition of a semiconductor wafer and a vertical heat treatment apparatus, which can improve the productivity of one-cycle processing.
[0002]
[Prior art]
As a method of improving the quality of a device active region of a silicon wafer against heavy metal contamination in a device process, there is a method of growing a polysilicon or silicon nitride on a back surface to give an extrinsic gettering (EG) effect. .
[0003]
Typically, the process of growing polysilicon or silicon nitride uses a vertical or horizontal heat treatment furnace.
In a vertical heat treatment furnace, one wafer is transferred to one groove of a boat for loading a plurality of wafers to perform a film forming process.
On the other hand, in a horizontal heat treatment furnace, a method of performing film formation by stacking two non-film-formed surfaces of wafers together (back-to-back method) is also used.
[0004]
[Problems to be solved by the invention]
Conventionally, in the vertical heat treatment furnace, the reason why the back-to-back method with high processing efficiency could not be performed was that a boat was composed of a plurality of boat posts, and the boat posts were narrow members in which grooves serving as shelves were arranged at predetermined intervals. The wafer is placed and supported by using a plurality of boat supports to support a plurality of locations on the outer periphery of the wafer with grooves, but (A) when two wafers are loaded in the groove, the There is a problem that the loaded wafer may drop, and (B) the film thickness decreases at the support contact portion in the groove of the boat support of the lower wafer when two wafers are loaded in one groove of the boat. Was.
[0005]
In view of the above situation, the present invention can realize a back-to-back system in a vertical heat treatment furnace, stably mount two wafers on one shelf of a boat, and can make the film thickness uniform, thereby improving productivity. It is an object of the present invention to provide a method for vapor-phase growth and deposition of a semiconductor wafer and a vertical heat treatment apparatus in which the temperature is improved.
[0006]
[Means for Solving the Problems]
As a result of various investigations aimed at eliminating the problems of the back-to-back method performed in the vertical heat treatment furnace, such as the falling of the overlying wafer and the decrease in the film thickness near the groove of the boat support, the boat shelf was The wafer contact surface of the groove forming the groove is inclined downward toward the center of the wafer, that is, by forming only the outermost peripheral portion of the wafer to be in contact, the film thickness can be made uniform, and the wafer can be inclined by a required angle. It has been found that by placing the wafer on the wafer, the fall of the wafer placed on the wafer can be prevented and the object can be achieved, and the present invention has been completed.
[0007]
According to the present invention, a plurality of boat supports having grooves arranged at predetermined intervals are used to support a plurality of locations on the outer peripheral portion of a semiconductor wafer inserted into a wafer support groove, and one or a single wafer is not formed in the one groove. When the two film surfaces are combined and inserted in a stack, two or more semiconductor wafers are loaded and loaded into a vertical heat treatment furnace, and when a thin film is vapor-phase grown on the back surface of the wafer,
(1) The contact area with the wafer back surface in each groove of the boat has a downward inclination of 1 ° to 20 ° from the horizontal to reduce the contact area with the wafer back surface ,
(2) and parallel so inclined erected in the range of 1 ° ~ 6 ° each semiconductor wafer from the horizontal,
This is a method for vapor-phase growth of a semiconductor wafer with improved productivity.
[0008]
In addition, the present invention reduces the contact area with the wafer back surface by giving the contact portion with each wafer back surface in each groove of the boat a downward inclination of 1 ° to 20 ° from the horizontal , and reduces each semiconductor wafer by 1 ° from the horizontal . We also propose a vertical heat treatment apparatus that can load a plurality of semiconductor wafers and load them into a heat treatment furnace by using a plurality of boat supports that are tilted and erected in parallel in the range of up to 10 ° .
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The conventional boat support 10 used in the vertical heat treatment furnace is a narrow member in which grooves 11 serving as shelves are arranged at predetermined intervals when semiconductor wafers 5 are placed, as shown in FIG. As shown in FIG. 2B, a plurality of the boat posts 10 are shown. For example, three to five boat posts 10 are used to form a boat 12, and a plurality of locations on the outer periphery of the semiconductor wafer 5 are supported by the groove portions 11 of the boat posts 10. Thus, the semiconductor wafer 5 is placed and supported.
[0010]
In the boat support 1 according to the present invention, as shown in FIG. 1A, the semiconductor wafer 5 inserted into the groove 2 is formed such that the wafer support region 3 of the groove 2 forms a downward slope of 1 to 45 ° from horizontal. The contact area of the back surface with the wafer support region 3 is significantly reduced as compared with the conventional boat support 10. For example, the wafer support region 3 of the groove 2 of the boat support 1 and the back surface of the semiconductor wafer 5 during the polysilicon reaction are reduced. The source gas can be more efficiently introduced into the vicinity of the contact surface, and the uniformity of the thickness of the film to be formed can be greatly improved.
[0011]
In the present invention, the angle (θ) of the downward slope formed in the wafer support region 3 of the groove 2 of the boat support 1 is at least 1 ° or more in order to reduce the contact area between the support and the back surface of the semiconductor wafer 5. Although it is necessary, if the angle of inclination is large, it becomes difficult to support the semiconductor wafer 5, so the angle is set to 45 ° or less. The preferred angle of inclination is between 8 ° and 20 °.
[0012]
Also, as shown in FIG. 2A, for example, the position of the groove 2 of the boat support 1 on the center side is set higher than the position of the groove 2 of the left boat support 1 in the drawing in the diameter direction of the semiconductor wafer 5. Thus, the semiconductor wafer 5 is erected from the horizontal by 1 ° to 20 °, and even if two semiconductor wafers 5 are inserted into the same groove portion 2 with the non-film-forming surfaces together, the semiconductor wafer 5 is slipped. The falling of the wafer 5 can be prevented.
[0013]
The angle of inclination of the semiconductor wafer 5 is required to be at least 1 ° or more in order to prevent the semiconductor wafer 5 from dropping. However, if the angle of inclination is large, the variation in the thickness of the deposited film becomes extremely large. The following is preferable. Further, when the inclination angle exceeds 10 °, the variation becomes 5% or more. Therefore, a more preferable inclination angle is 1 ° to 10 °.
[0014]
Further, as shown in FIG. 3, when two wafers are loaded on the boat 6 according to the present invention and the wafers are mounted at a required angle to perform a film forming process, the wafers can be prevented from dropping during the heat treatment, and A decrease in the thickness of the contact portion in the groove 2 of the boat support 1 on the back surface of the semiconductor wafer 5 transferred to the lower side can be eliminated, and the productivity in the vertical heat treatment furnace can be greatly improved.
[0015]
【Example】
Example 1
Using various boats in which the inclination angle of the wafer support region of the boat support groove is set to 1 °, 8 °, 20 °, and 45 °, one silicon wafer with an oxide film is transferred to each boat support groove, A polysilicon thin film was grown to about 1.4 μm under the conditions of a film temperature of 620 to 670 ° C., a furnace pressure of 0.1 to 0.8 Torr, and SiH ₄ gas.
[0016]
Thereafter, the results of measuring the film thickness at five points within the plane of the wafer with an ellipsometer are shown in Table 1. The in-plane variation of the boat other than the wafer support region is substantially uniform, but the thickness difference between the support region and the other surface decreases as the inclination angle increases. However, it has been found that when the tilt angle is large, it becomes difficult to support the wafer.
[0017]
Comparative Example 1
Using a conventional boat having an inclination angle of 0 ° in the wafer support region of the boat support groove, a polysilicon film was grown in the same manner as in Example 1, and the film thickness was measured using an ellipsometer. Table 1 shows the results. The difference in film thickness in the wafer support region of the boat was reduced by about 20% as compared with the region other than the contact portion.
[0018]
Example 2
The wafer is tilted upright at various angles of 1 °, 3 °, 6 °, 10 °, and 20 ° in a boat having an 8 ° tilt angle in the wafer support region of the boat support groove shown in FIG. 2A. Then, two wafers were stacked in one groove, and a polysilicon film was grown to about 1.4 μm under the same conditions as in Example 1.
Thereafter, the in-plane film thickness of the upper and lower stacked wafers other than the wafer support was measured by an ellipsometer. No difference in film thickness between the upper and lower wafers was observed, and when the inclination angle was within 10 °, the variation in the film thickness within the wafer surface was within 5%, and when the inclination angle was greater than 10 °, the variation exceeded 5%. Therefore, a preferable inclination angle is 1 ° to 10 °.
[0019]
[Table 1]

[0020]
[Table 2]

[0021]
【The invention's effect】
The present invention realizes a back-to-back method with high processing efficiency in a vertical heat treatment furnace, and forms a downwardly inclined surface in a wafer support region of a groove portion of a boat support to form a boat as shown in an embodiment. When two wafers are loaded on the shelf and the wafers are placed at a required angle, the film is deposited. This prevents the wafers from dropping during the heat treatment and prevents the wafers from being moved downward. It is also possible to eliminate a decrease in the film thickness of the contact portion in the groove, and it is possible to greatly improve the productivity in the vertical heat treatment furnace.
[Brief description of the drawings]
FIG. 1A is an explanatory view of a boat support for a vertical heat treatment apparatus according to the present invention, and FIG. 1B is an explanatory view of a conventional boat support.
FIG. 2A is an explanatory diagram showing a vapor deposition method using a boat according to the present invention, and FIG. 2B is an explanatory diagram showing a vapor deposition method using a conventional boat.
FIG. 3 is an explanatory view showing a vapor phase growth film forming method using a boat according to the present invention.
[Explanation of symbols]
1,10 Boat support 2,11 Groove 3 Wafer support area 5 Semiconductor wafer 6,12 Boat

Claims (3)

Using a plurality of boat pillars having grooves arranged at predetermined intervals, supports a plurality of locations on the outer periphery of the semiconductor wafer inserted into the wafer support groove, loads a plurality of semiconductor wafers, and loads the semiconductor wafer into a vertical heat treatment furnace In vapor-phase growth of a thin film on the backside of the wafer, the contact portion of each groove of the boat with the backside of the wafer has a downward inclination of 1 ° to 20 ° from the horizontal to reduce the contact area with the backside of the wafer , and each semiconductor A method for vapor-phase growth and deposition of a semiconductor wafer in which the wafer is tilted upright in a range of 1 ° to 6 ° from horizontal . Oite to claim 1, vapor deposition method of forming a semiconductor wafer to be inserted by the combined non-deposition surfaces of the wafer in each groove of the boat in two-ply. The contact portion of each groove of the boat with the backside of the wafer has a downward slope of 1 ° to 20 ° from the horizontal to reduce the contact area with the backside of the wafer , and each semiconductor wafer has a range of 1 ° to 6 ° from the horizontal. A vertical heat treatment apparatus in which a plurality of semiconductor wafers are stacked and loaded into a heat treatment furnace by using a plurality of boat supports that are erected in parallel .

Images