DEVICE AND METHOD TO ACHIEVE HOMOGENEOUS GROWTH AND DOPING OF SEMICONDUCTOR WAFERS WITH A DIAMETER GREATER THAN 100 MM

Abstract

Device for achieving homogeneous thickness growth and doping on a semiconductor wafer (2) with a diameter greater than 100 mm during growth at elevated temperature in a growth chamber arranged in a reactor housing comprising a growth chamber (14) with a wafer (2) on a rotating susceptor (3), where the growth chamber (14) has, an inlet channel (17) for the supply of process gases and an outlet channel (18) for discharge of unused process gases to create a process gas flow over the semiconductor wafer (2), and an injector (4) at the end of the inlet channel (17) where it opens into the growth chamber (14), where the injector (4) is divided into at least 3 gas ducts with a first gas duct B and at each side of it a second gas channel A and a third gas channel C, and where the magnitude of the gas flow in the gas duct B and gas concentrations in the gas duct B are arranged to be controlled independent of gas flows and gas concentrations in gas channels A and C.

Claims

1. Device for achieving homogeneous thickness growth and doping in a semiconductor wafer with a diameter greater than 100 mm during growth at elevated temperature in a growth chamber arranged in a reactor housing, wherein the device comprises: a growth chamber having a port to allow insertion of at least one wafer on a rotating susceptor in the growth chamber and for removing the wafer therefrom, where the growth chamber further has an inlet channel for supplying process gases and an outlet channel for discharge of unused process gases to create a process gas flow over the semiconductor wafer between said channels, wherein an injector for creating a laminar flow of the process gases in the growth chamber is arranged at the end of the inlet channel where it opens into the growth chamber, the injector is divided into at least 3 gas ducts with a first gas duct Band at each side thereof a second gas duct A and a third gas duct C, the magnitude of the gas flow in the gas channel B and gas concentrations in the gas channel B are arranged to be controlled independently of gas flows and gas concentrations in the gas ducts A and C.

2. The device according to claim 1, wherein the gas ducts A and C have the same cross-sectional area and when growing a wafer the same gas flow and gas concentrations.

3. The device according to claim 1, wherein the three gas ducts A, B and C are located in the same plane.

4. The device according to claim 1, wherein the gas ducts A, B and C are arranged to run parallel to each other.

5. The device according to claim 1, wherein the gas duct B has an opening angle in the range 5-30 degrees and where the gas ducts A and C have opening angles in the range 5-30 degrees.

6. The device according to claim 1, wherein the gas duct B has an opening angle in the range 10-30 degrees and where the gas ducts A and C have opening angles in the range 10-30 degrees.

7. The device according to claim 5, wherein the opening angles of the outer gas ducts A and C are preferably smaller than the opening angle of the middle gas channel B.

8. The method of claim 1 for achieving homogeneous thickness growth of a semiconductor wafer with a diameter greater than 100 mm during growth at elevated temperature in a growth chamber set up in a reactor housing, wherein: the concentration of active gases precursors is increased in the side channels in relation to the concentration of active gases in the middle channel to achieve increased thickness growth of the wafer in its peripheral areas.

9. The method of claim 1, for achieving homogeneous doping in a semiconductor wafer with a diameter greater than 100 mm during growth at elevated temperature in a growth chamber set up in a reactor housing, wherein the concentration of dopant gases is increased in the side channels in relation to the concentration of doping gases in the center channel to achieve increased doping of the wafer in its peripheral areas.

10. A method according to claim 8, wherein: a radially wider part of the outer areas of the wafer is affected by the gas flow via the side channels by an increase of the gas flow in the side channels relative to the gas flow in the middle gas duct.

Description

DESCRIPTION OF FIGURES

[0022] FIG. 1 schematically shows a principal diagram of the device according to the aspect of the invention where three gas ducts are shown in an injector in connection with a growth of a semiconductor wafer.

[0023] FIG. 2 illustrates a perspective view of the device according to FIG. 1 where the gas ducts are shown with a certain opening angle towards the semiconductor wafer.

[0024] FIG. 3 shows an example of a reactor of the type used according to the invention.

Description of Embodiments

[0025] In the following, a number of embodiments of the invention are described with reference to the accompanying drawings. The drawings show only schematically the principle of the device and do not claim to show to any scale any proportions between different elements thereof.

[0026] An embodiment of a device according to the invention is presented here. By adapting the elements shown in the present described embodiment to other designs of reactors, the principle of the invention can be transferred to them.

[0027] The device according to the invention is shown, very schematically, inside a reactor 10 in FIG. 3, where the reactor is designed with a cylindrical housing formed with a reactor bottom 11, lid 12 and cylindrical wall 13. A reactor according to FIG. 3 is usually designed in stainless steel. The figure shows a cross-section through the reactor 10, whereby a growth chamber 14 opens inside the reactor, which is opened in a longitudinal cross-section. The growth chamber is made of a very heat-resistant material. The growth chamber 14 is seen here with a bottom 1 and an upper wall 16. A susceptor 3 is shown immersed in the bottom 1 of the growth chamber, where it is rotatably arranged in the same plane as this. The reactor 10 has a port for supplying process gases, which are introduced into the growth chamber 14 via an inlet channel 17 which at its outlet to the growth chamber 14 has an injector 4, where the process gases are symbolized by an arrow in the injector 4. Furthermore, the reactor 10 has a port for discharge of unused process gases, where these are discharged via an outlet channel 18 from the growth chamber 14. In this outlet channel 18, this flow of unused process gases is shown by means of an arrow inside the outlet channel 18.

[0028] FIG. 1 shows a bottom 1 in a growth chamber 14 for growing semiconductor wafers. In the following, a semiconductor wafer is indicated very briefly as using only the term wafer. A wafer denoted by 2 is shown in the figure arranged on a susceptor which is rotated, whereby the wafer 2 will rotate in the growth chamber 14. In FIG. 1 the susceptor 3 is completely covered by the wafer 2. In connection with the channel to the growth chamber 14, the injector 4 for process gases is set up. The injector 4 feeds the process gases required for the intended growth into the growth chamber 14. The gases which form part of the process gas flow are of the same sort as according to the prior art in the growth of specific semiconductors.

[0029] The injector 4 is, according to the invention, divided into at least 3 gas ducts, here referred to as the gas ducts A, B and C. B is a central gas duct which has the main gas flow into the growth chamber 14. At each side of the central gas duct B are side gas ducts A resp. C arranged. The side gas ducts A and C are directed towards the peripheral parts of the wafer 2 and supply process gases in a flow over the wafer. Since the wafer 2 is arranged rotating, the gas flow over the peripheral parts of the wafer is uniformly distributed over them. Arrow 5 schematically shows gas flows from the injector 4 into the growth chamber 14 in the direction of the rotating wafer 2.

[0030] As shown in FIG. 2, the gas ducts A, B and C are provided with opening angles α, β, γ towards the outlet of the injector 4. The nozzles of the injector 4 supply a laminar flow of process gases to the growth chamber 14. The opening angles in the different gas ducts A, B and C are selected so that they do not affect the laminar flow out of the injector. Suitable opening angles α, β, γ are in the range 5-30 degrees, preferably 10-30 degrees. Maximum angle depends, among other things, on gas flow, temperature, and gas. The opening angle can be selected less than 10 degrees if it is advantageous for manufacturing technical reasons.

[0031] The opening angles in the outer gas ducts A and C are preferably smaller than the opening angle in the middle gas duct B.