CN202076271U

CN202076271U - Epitaxial layer structure of back sealing monocrystalline silicon

Info

Publication number: CN202076271U
Application number: CN2011203516451U
Authority: CN
Inventors: 钟旻远; 林志鑫; 顾昱; 陈斌
Original assignee: WAFER WORKS EPITAXIAL CORP
Current assignee: WAFER WORKS EPITAXIAL CORP
Priority date: 2011-09-19
Filing date: 2011-09-19
Publication date: 2011-12-14
Anticipated expiration: 2021-09-19

Abstract

The utility model relates to a epitaxial layer structure of back sealing monocrystalline silicon, which comprises a heavy doping substrate and an epitaxial layer on the heavy doping substrate. A layer of monocrystalline silicon without doping is covered on the back surface of the heavy doping substrate. The epitaxial layer structure of the back sealing monocrystalline silicon has the advantages that a layer of epitaxial back sealing without resistance is added to the back of the substrate so as to improve the self-doping phenomenon of the substrate.

Description

Back of the body envelope single-crystal Si epitaxial layers structure

Technical field

The utility model relates to a kind of monocrystalline silicon, relates in particular to the back of the body seal structure of this monocrystalline silicon.

Background technology

The mainspring of development silicon epitaxy is in order to improve the performance of bipolar transistor and bipolar integrated circuit afterwards.

Epitaxial loayer is to have to extend on original crystal (being commonly referred to as substrate) of certain crystalline orientation and by the method for certain crystallographic direction growing film, this single crystalline layer is called epitaxial loayer.

Epitaxial growth with from melt, directly draw body monocrystalline (lining body) the following advantage of having compared:

1. can be under the temperature that is lower than the substrate fusing point growing semiconductor monocrystal thin films;

2. can grow thin layer, epitaxially deposited layer and low dimensional structures material;

3. can growth components or Impurity Distribution is precipitous or the epitaxial loayer of gradual change;

4. can in the substrate appointed area, carry out selective epitaxial growth.

The epitaxial loayer development makes semiconductor device move towards energy band engineering from the impurity engineering, the application of epitaxial loayer and development are for the quality that improves semi-conducting material and the performance of device, for the exploitation of new material, new unit, development has crucial effects for semiconductor science.

As seen from Figure 1: the structure of prior art monocrystalline silicon is made up of heavy doping substrate 1 and top epitaxial loayer 2.But the problem that this kind structure exists is:

For semiconductor device, wish that not only epitaxial loayer has perfect crystal structure, and also there is certain requirement aspects such as thickness, conduction type and resistivity.

Because can there be the bigger problem of epilayer resistance uniformity scope in the influence of heavily doped lining body autodoping, in addition, autodoping seriously also can influence the Impurity Distribution that has sudden change between epitaxial loayer and the substrate in epitaxial process.Especially along with the development of microwave device and very high speed integrated circuit, not only require epitaxial loayer more and more thinner, but also require the Impurity Distribution on both sides, interface more and more steeper.

In the production process of epitaxial wafer, exist general auto-doping phenomenon.Autodoping be since the accessory substance of thermal evaporation or chemical reaction to the diffusion of substrate, silicon and impurity in the substrate enter gas phase, have changed doping composition and the concentration in the gas phase, thereby have caused the impurity actual distribution in the epitaxial loayer to depart from ideal situation.By the reason that produces, autodoping can be divided into gas phase autodoping, solid phase outdiffusion and system's autodoping.The alloy of gas phase autodoping is mainly from the back side and the edge solid phase outdiffusion of wafer.Mainly from the diffusion of substrate, alloy diffuses to epitaxial loayer at the contact-making surface of substrate and epitaxial loayer by substrate to the alloy of solid phase outdiffusion.The alloy of system's autodoping is from the gas wafer, the inside of graphite plate and reacting furnace cavity homepitaxy sheet process units.

Generation reason by autodoping can find out that in the epitaxial wafer production process, especially in the production method of vapour phase epitaxy, auto-doping phenomenon is difficult to avoid.

Be illustrated in figure 2 as a kind of schematic diagram of epitaxial wafer, because the influence of autodoping, 1. locate the highlyest, 2., 3., 4., 5. locate to take second place with respect to the outer ring resistance value, edge 6., 7., 8., 9. to locate resistance lower relatively.The inhomogeneity standard of gauge resistor can be calculated computing formula by computing formula: the * 100%/(MAX+MIN) of resistivity evenness=(MAX-MIN), and MAX is a maximum value numerical value in 9 points, MIN is a minimum resistance numerical value in 9 points.The uniformity numerical value that calculates by this computing formula is more little, and then its uniformity is high more, and the epitaxial wafer quality is high more.

At present, can accept scope less than 5% for the resistivity evenness of epitaxial wafer.Epitaxial wafer of the prior art, its resistivity evenness is minimum also only to reach 2.5%.

Summary of the invention

The utility model technical issues that need to address have provided a kind of back of the body envelope single-crystal Si epitaxial layers structure, are intended to solve the above problems.

In order to solve the problems of the technologies described above, the utility model is achieved through the following technical solutions:

The utility model comprises: heavy doping substrate and top epitaxial loayer; Also cover the monocrystalline silicon that one deck does not contain doping at described heavy doping substrate back.

Compared with prior art, the beneficial effects of the utility model are: adding one deck behind the utilization substrate does not have resistance extension back of the body envelope, can effectively improve the auto-doping phenomenon of substrate.

Description of drawings

Fig. 1 is a prior art monocrystalline silicon back of the body seal structure schematic diagram.

Fig. 2 is a kind of schematic diagram of epitaxial wafer.

Fig. 3 is the utility model structural representation.

Embodiment

Below in conjunction with accompanying drawing and embodiment the utility model is described in further detail:

As seen from Figure 3: the utility model comprises: heavy doping substrate 1 and top epitaxial loayer 2; Also cover the monocrystalline silicon 3 that one deck does not contain doping at described heavy doping substrate 1 back side.

Described monocrystalline silicon 3 thickness of doping that do not contain are within 20um.

Described thickness is 5um or 10um or 15um.

The utility model can effectively change substrate autodoping situation.After substrate back generates one deck thin single crystal silicon, monocrystalline silicon arrives in the reacting furnace by the thin epitaxy of growing in the mode of high temperature with diffusion, not only can not have influence on the reaction of trichlorosilane and hydrogen in silicon atom in the diffusion and the reacting furnace, because silicon atom is the reactant product that need obtain just, arrange so can't have influence on the monocrystalline silicon of substrate face.

Epitaxial growth is the monocrystalline silicon back of the body seal of being realized by vapour deposition by the epitaxial furnace board.Vapour phase epitaxy has good control and can obtain perfection of crystal impurity concentration.

Epitaxial deposition is the process of a chemical deposition.Below five steps for the basic process of all chemical vapour deposition (CVD)s:

1. reactant is transported on the substrate

2. reactant is attracted on the lining surface

3. chemical reaction takes place on the surface easily generate monocrystalline silicon and product

4. product is emitted from the surface

5. product is transported from the surface

The reactive chemistry equation:

2SiHCl3+2H2→2SI+6HCL

Advantage the utility model mainly contains 5 in IC makes aspect:

(1) substrate impurity (as phosphorus, boron, arsenic atom) is played good masking action;

(2) help substrate face to arrange monocrystalline silicon in order;

(3) passivation silicon chip surface is that the surface and the surrounding environment of device isolated, and prevents to stain, and can improve the performance of device and the reliability and stability of device;

(4) do insulating barrier, for example do the insulating barrier of dielectric isolation, the insulating barrier of metal lead wire and each element etc. in the integrated circuit;

(5) do the medium of electric capacity;

(6) do gate oxide among the MOS

Contrast Fig. 2: example 1

	Point 1	Point 2	Point 3	Point 4	Point 5	Point 6	Point 7
								Original structure	0.959	0.967	0.976	0.971	0.97	0.97	0.978
The utility model	0.967	0.974	0.974	0.973	0.973	0.973	0.977

	Point 8	Point 9	AVE	MAX	MIN	UNI
							Before the improvement	0.978	0.968	0.971	0.978	0.959	0.98％
After the improvement	0.974	0.977	0.974	0.977	0.967	0.51％

Example 2

Claims

1. a back of the body envelope single-crystal Si epitaxial layers structure comprises: heavy doping substrate and top epitaxial loayer; It is characterized in that: also cover the monocrystalline silicon that one deck does not contain doping at described heavy doping substrate back.

2. back of the body envelope single-crystal Si epitaxial layers structure according to claim 1, it is characterized in that: the described monocrystalline silicon thickness of doping that do not contain is within 20um.

3. back of the body envelope single-crystal Si epitaxial layers structure according to claim 2, it is characterized in that: described thickness is 5um or 10um or 15um.