Growth of doped semiconductor monolayers

• US 5,693,139 A
• Filed: 06/15/1993
• Issued: 12/02/1997
• Est. Priority Date: 07/26/1984
• Status: Expired due to Fees

• Current Assignee: Research Development Corporation Of Japan (Japan Science And Technology Agency), OKI Electric Industry Company Limited, Tohoku University National Universities Corporation
• Original Assignee: Research Development Corporation Of Japan (Japan Science And Technology Agency), Jun-Ichi Nishizawa, OKI Electric Industry Company Limited, Soubei Suzuki
• Inventors: Abe, Hitoshi, Nishizawa, Junichi, Suzuki, Soubei
• Primary Examiner(s): KUNEMUND, ROBERT M
• Application Number:
  US08/077,119
• Time in Patent Office: 1,631 Days
• Field of Search: 437/102, 437/103, 427/243, 427/255.1, 117/953, 117/954, 117/956, 117/89, 117/93, 117/102, 117/105
• US Class Current: 117/89
• CPC Class Codes: C23C 16/455 characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
• CPC Class Codes: C23C 16/45525 Atomic layer deposition [ALD]
• CPC Class Codes: C23C 16/45531 specially adapted for making ternary or higher compositions
• CPC Class Codes: C23C 16/45536 Use of plasma, radiation or electromagnetic fields
• CPC Class Codes: C30B 25/02 Epitaxial-layer growth
• CPC Class Codes: C30B 25/14 Feed and outlet means for the gases; Modifying the flow of the reactive gases
• CPC Class Codes: C30B 29/42 Gallium arsenide
• CPC Class Codes: H01L 21/02395 Arsenides
• CPC Class Codes: H01L 21/02543 Phosphides
• CPC Class Codes: H01L 21/02546 Arsenides
• CPC Class Codes: H01L 21/02576 N-type
• CPC Class Codes: H01L 21/02579 P-type
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD

Abstract

A cycle of alternately or cyclically introducing external gases containing molecules of component elements of a compound semiconductor to be formed on a substrate is repeated while appropriately controlling the pressure, substrate temperature and gas introduction rate in a crystal growth vessel, so that a monocrystal which is dimensionally as precise as a single monolayer can grow on the substrate by making use of chemical reactions on the heated substrate surface.

Doped molecular layer epitaxy of a compound semiconductor comprising individual steps of introducing and evacuating a first source gas, introducing and evacuating a second source gas, and introducing and evacuating an impurity gas which contains an impurity element. The doped impurity concentration varies almost linearly with the pressure during doping in a wide range.

Claims

1. A method of doping a compound semiconductor single crystal layer being grown in monolayers on a heated substrate in a growth chamber by alternate introduction of source gases, the growth chamber being evacuated continuously at a continuous rate of evacuation throughout the whole method, the method comprising the steps of:

(a) introducing a first source gas containing one constituent element of the compound into the growth chamber of at least a sufficient quantity for growing one monolayer, the supply of the first source gas being thereafter stopped and the growth chamber still being kept under the continuous rate of evacuation to evacuate residual of the first source gas;

(b) introducing a second source gas containing another constituent element of the compound into the growth chamber of at least a sufficient quantity for growing one monolayer, the supply of the second source gas being thereafter stopped and the growth chamber still being kept under the continuous rate of evacuation to evacuate residual of the second source gas;

(c) doping an impurity gas into the growth chamber, the impurity gas being of a particular type and having impurities which enter into sites in the monolayer being grown;

(d) initially carrying out steps (a), (b) and (c) to grow a monolayer on the substrate and then growing monolayers one over the other by cyclically repeating steps (a), (b) and (c) to grow a new monolayer on the monolayer just previously grown; and

(e) selectively implementing an order in which steps (a), (b) and (c) take place during each cycle of step (d) based on the particular type of impurity gas being doped and selectively timing when step (c) takes place with respect to the timing of steps (a) and (b) based on obtaining a desired dopant type for the monolayer being grown and a desired level of impurity concentration in the monolayer being grown,

wherein said compound is a group III-V compound and the impurity gas contains an element belonging to one of group II, group IV and group VI of the periodic table, the constituents from the first source gas are of a group III element and the constituents from the second source gas are of a group V element, the order in which steps (a), (b) and (c) are carried out is in accordance with a sequence selected from the group consisting of;

steps (a), (c) and (b) in succession where impurities from the impurity gas are selected from the group consisting of group IV element forming a donor, group II element and group VI element;

steps (a), (b) and (c) in succession where impurities from the impurity gas are selected from the group consisting of group IV element forming an acceptor, group II element and group VI element, whereby the continuous evacuation causes evacuation of residual waste of the first source gas, the second source gas, and the impurity gas.

7. A method as in claim 1, wherein the substrate is heated to a temperature of about 300°

C. to 800°

C.

8. A method as in claim 1, wherein the second source gas is triethyl gallium (TEG).

10. A method as in claim 1, wherein the repeating includes successively growing monolayers on the substrate to a desired thickness to form an epitaxial layer with a thickness controlled to an accuracy of monolayer order.

11. A method as in claim 1, wherein steps (a) to (e) take place to grow the crystal layer with desired impurity concentration, crystalline quality, carrier mobility and surface morphology.

12. A method as in claim 1, wherein the growth chamber has a discharge area through which the continuous evacuation takes place, the substrate being arranged between the discharge area and where the first and second source gas introductions take place within the growth chamber.

13. A method as in claim 1, wherein the step (a), (c), and (b) in succession of doping takes place so that the grown crystal layer has a mirror-like surface.

14. A method as in claim 1, wherein the step (a), (c), and (b) in succession of doping takes place so that mobility of carriers for the crystal layer reaches 1600 cm² V^-1 sec^-1.

15. A method as in claim 1, wherein the first source gas is arsine.

25. A method as in claim 1, wherein the compound is GaAs.

26. A method as in claim 1, wherein the impurity gas is one of dimethyl-cadmium (DMCd), Si₂ H₆, tri-methyl-gallium (TMG), di-ethyl-selenium (DESe), and H₂ Se.

27. A method as in claim 1, wherein the impurity gas contains silicon serving as an n-type impurity and the step (c) is carried out after exhausting in each cycle waste second source gas which contains gallium.

28. A method as in claim 1, wherein the impurity gas contains carbon serving as a p type impurity and the step (c) is carried out after exhausting in each cycle waste first source gas which contains arsenic.

2. A method of doping a compound semiconductor single crystal layer being grown in monolayers on a heated substrate in a growth chamber by alternate introduction of source gases, the growth chamber being evacuated continuously at a continuous rate of evacuation throughout the whole method, the method comprising the steps of:

(a) introducing a first source gas containing one constituent element of the compound into the growth chamber of at least a sufficient quantity for growing one monolayer, the supply of the first source gas being thereafter stopped and the growth chamber still being kept under the continuous rate of evacuation to evacuate residual of the first source gas;

(b) introducing a second source gas containing another constituent element of the compound into the growth chamber of at least a sufficient quantity for growing one monolayer, the supply of the second source gas being thereafter stopped and the growth chamber still being kept under the continuous rate of evacuation to evacuate residual of the second source gas;

(c) doping an impurity gas into the growth chamber, the impurity gas being of a particular type and having impurities which enter into sites in the monolayer being grown;

(d) initially carrying out steps (a), (b) and (c) to grow a monolayer on the substrate and then growing monolayers one over the other by cyclically repeating steps (a), (b) and (c) to grow a new monolayer on the monolayer just previously grown; and

(e) selectively implementing an order in which steps (a), (b) and (c) take place during each cycle of step (d) based on the particular type of impurity gas being doped and selectively timing when step (c) takes place with respect to the timing of steps (a) and (b) based on obtaining a desired dopant type for the monolayer being grown and a desired level of impurity concentration in the monolayer being grown,

wherein the order in which steps (a), (b) and (c) take place is in accordance with an ascending numerical order of periodic table group types associated with the first source gas, the second source gas and the impurity gas, wherein the compound is a group III-V compound and the impurity gas contains an element belonging to one of the group II, group IV serving as a donor and group VI of the periodic table,

whereby the continuous evacuation causes evacuation of residual waste of the first source gas, the second source gas, and the impurity gas.

3. A method as in claim 2, wherein the compound is GaAs.

4. A method as in claim 2, wherein the impurity gas is one of di-methyl-cadmium (DMCd), Si₂ H₆, tri-methyl-gallium (TMG), di-ethyl-selenium (DESe), and H₂ Se.

5. A method as in claim 2, wherein the impurity gas contains silicon serving as an n-type impurity and the step (c) is carried out after exhausting in each cycle waste second source gas which containing gallium.

6. A method as in claim 2, wherein the impurity gas contains carbon serving as a p type impurity and the step (c) is carried out after exhausting in each cycle waste first source gas which contains arsenic.

9. A method as in claim 2, wherein the constituents from the first source gas are of a group III element and the constituents from the second source gas are of a group V element, the order in which steps (a), (b) and (c) are carried out is in accordance with a sequence selected from the group consisting of steps (c), (a) and (b) in succession where impurities from the impurity gas are of the group II element, steps (a), (c) and (b) in succession where impurities from the impurity gas are of the group IV element forming a donor, steps (a), (b) and (c) in succession where impurities from the impurity gas are of the group IV element forming an acceptor, and steps (a), (b) and (c) in succession where impurities from the impurity gas are of the group VI element.

16. A method of forming a single crystalline thin fill of a III-V or a II-VI compound semiconductor comprising the steps of:

(a) continuously evacuating the interior of a crystal growth vessel at a constant rate of evacuation;

(b) heating a substrate disposed in the crystal growth vessel to a temperature of from about 300 to 800 degrees C;

(c) introducing into the crystal growth vessel, under a first deposition pressure of from about 10.sup.^-1 to 10^-7 Pascal and for a first time period of from about 0.5 to 200 seconds, sufficient quantity of gaseous molecules of a first compound to form at least a single molecular layer of the first compound on the substrate, the first compound selected from the group consisting of group III and group II compounds respectively, which first compound contains a first constituent element of the III-V or II-VI compound semiconductor;

(d) further introducing into the crystal growth vessel, under a second deposition pressure of from about 10^-1 to 10^-7 Pascal and for a second time period of from about 0.5 to 200 seconds, sufficient quantity of gaseous molecules of a second compound to form at least a single molecular layer of the second compound on the substrate, the second compound selected from the group consisting of group V and group VI compounds respectively, which second compound contains a second constituent element of the II-V or II-VI compound semiconductor;

a single monolayer or a dimolecular layer growing in one cycle of said introduced gaseous molecules of first and second compounds corresponding to a saturation thickness in one cycle,

the single-crystalline film being at least n times as thick as a single molecular layer of the compound semiconductor, where n is an integer of 1, 2 or larger to cause growth of a monocrystalline thin film of the compound semiconductor having dimensions as precise as a single molecular layer, the step (a) being continuous for evacuating any waste of the gaseous molecules introduced to form the first and second compound;

introducing first dopant gaseous molecules, the first dopant gaseous molecules being of a first dopant compound containing a first dopant element of the GaAs compound semiconductor;

introducing second dopant gaseous molecules, the second dopant gaseous molecules being of a second dopant compound containing a second dopant element of the GaAs compound semiconductor; and

cyclically repeating the steps (c) and (d) while heating the substrate and continuously evacuating the growth chamber so as to cause growth of a single-crystalline thin film of the compound semiconductor having a thickness determined by the number of the cyclical repetitions, the thickness being dimensionally as precise as a monolayer.

17. A method as in claim 16, wherein the step of heating the substrate includes irradiating the substrate with light having a wavelength of 180 to 600 nm.

18. A method as claim 16, wherein the first compound is selected from the group consisting of TMG, TEG, DEGaCl, GaBr₃ and GaI₃, and the second compound is selected from the group consisting of TMAs, AsCl₃, AsBr₃ and AsH₃, and the compound semiconductor is GaAs.

19. A method as in claim 16, wherein:

(a) the first dopant gaseous molecules are molecules of a first dopant compound selected from the group consisting of DMZn, DEZn, DECd, DMHg, DEHg and B₂ H₆ and providing gaseous molecules containing a p-type dopant element of the GaAs compound semiconductor;

(b) the second dopant gaseous molecules are molecules of second dopant compound selected from the group consisting of SiH₄, GeH₄, SnH₄, PbH₄, DMSe, DMTe, H₂ S, H₂ Se, H₂ Te and H₂ Po and providing gaseous molecules containing n-type dopant elements of the compound semiconductor, and

(c) the first dopant gaseous molecules and the second dopant gaseous molecules are individually introduced simultaneously with at least one of the gaseous molecules of the first compound and the gaseous molecules of the second compound, wherein a dopant concentration distribution in the thicknesswise direction is provided.

20. A method as in claim 16, wherein a cycle of causing growth of at least one molecular layer is achieved by:

(a) introducing Al as the gaseous molecules of the first compound selected from the group consisting of TMAl, TEAl, DMAlCl, AlCl₃, AlBr₃ and AlI₃ ;

(b) introducing, simultaneously with the introducing Al as the gaseous molecules of the first compound gaseous molecules of a second compound containing at least one element of the Ga.sub.(1-x) Al_x As compound semiconductor other than Al, and

(c) further introducing, simultaneously with introducing Al as the gaseous molecules of the first compound and gaseous molecules of a second compound containing at least one element of the Ga.sub.(1-x)Al_x As compound semiconductor other than Al, gaseous molecules of a third compound which third compound contains a third constituent element of the Ga_1-x)Al_x As compound semiconductor other than Al and other than the gaseous molecules of the second compound, where 0<

x<

1, and evacuating the interior of the crystal growth vessel, and repeating the simultaneous introduction of the gaseous molecules containing Al and the gaseous molecules containing at least one element other than At, and the gaseous molecules of a third compound containing a third constituent element of the Ga.sub.(1-x)Al_x As compound semiconductor, and evacuation to form a crystalline thin film of the Ga.sub.(1-x Al_x As compound semiconductor.

21. A method as in claim 16, further comprising the step of introducing into the crystal growth vessel gaseous molecules of a third compound selected from the group consisting of group II, group III, group V, group VI compounds, which third compound contains a third constituent element of the III-V or II-VI compound semiconductor, the third constituent element being selected from the group consisting of group II, III, V and VI elements other than the first and second constituent elements, the third constituent element being selected from the group consisting of group III and group V elements when the compound semiconductor is a III-V compound semiconductor, and the third constituent element being selected from the group consisting of group II and group VI elements when the compound semiconductor is a II-VI compound semiconductor to thereby form a heterogeneous structure of a binary compound semiconductor and a ternary compound semiconductor containing at least two different compound semiconductors on the substrate.

22. A method as in claim 21, further comprising the additional step of introducing into the crystal growth vessel gaseous molecules of a fourth compound selected from the group consisting of group II, group III, group V, group VI compounds, which fourth compound contains a fourth constituent element of the III-V or II-VI compound semiconductor, the fourth constituent element being selected from the group consisting of group II, III, V and VI elements other than the first, second or third constituent elements, the fourth constituent element being selected from the group consisting of group III and group V elements when the compound semiconductor is a III-V compound semiconductor, and the fourth Constituent element being selected from the group consisting of group II and group VI elements when the compound semiconductor is a II-VI compound semiconductor, to thereby form a heterogeneous structure of a compound semiconductor and a quaternary compound semiconductor consisting of at least two different compound semiconductors on the substrate by growth.

23. A method as in claim 21, wherein the step of introducing the gaseous molecules of the third compound is performed simultaneously with the step of introducing the gaseous molecules of the first compound, and the third compound is selected from the group of group V and group VI compounds.

24. A method as in claim 22 wherein the step of introducing the gaseous molecules of the fourth compound is performed simultaneously with the step of introducing the gaseous molecules of the second compound, and the fourth compound is selected from the group of group Ill and group II compounds.

29. A method of forming a monocrystalline thin film of a compound semiconductor comprising the steps of forming on a crystalline substrate a mask pattern of a material different from that of said substrate, disposing said substrate formed with said mask pattern in a crystal growth vessel after rinsing and drying, then evacuating the interior of said crystal growth vessel to a predetermined vacuum, heating said substrate, introducing gaseous molecules containing those of one component element of a compound semiconductor into said crystal growth vessel under a predetermined pressure for a predetermined period of time, evacuating the interior of said crystal growth vessel again, introducing gaseous molecules containing those of another component element of said compound semiconductor or containing a gas reacting with the first component element of said semiconductor into said crystal growth vessel under a predetermined pressure for a predetermined period of time, evacuating the interior of said crystal growth vessel again, and repeating a sequence of the above steps to cause growth of single monolayer, whereby a monocrystalline thin film of said compound semiconductor having a desired thickness is selectively formed on said substrate with precision as precise as a single monolayer.

30. A method as in claim 29, wherein said crystalline substrate is made of a compound semiconductor of III and V group elements and said gaseous molecules as the sources of the growth include III and V group elements.

31. A method as in claim 29, wherein said substrate is irradiated with light having a wavelength of 180 to 600 nm.

32. A method as in claim 30, further comprising the steps of using a film of Si_x N_y and/or a film of Si_x O_y as the material of said mask pattern and using a liquid containing trialkyl 2, 1-hydroxyalkyl ammonium hydroxide (THAH) as rinsing liquid for rinsing said substrate prior to the growth and also as an etchant.