CN103137444A

CN103137444A - Method for improving evenness of thickness of germanium-silicon membrane

Info

Publication number: CN103137444A
Application number: CN2011103884373A
Authority: CN
Inventors: 钱志刚; 季伟
Original assignee: Shanghai Hua Hong NEC Electronics Co Ltd
Current assignee: Shanghai Huahong Grace Semiconductor Manufacturing Corp
Priority date: 2011-11-29
Filing date: 2011-11-29
Publication date: 2013-06-05

Abstract

The invention discloses a method for improving evenness of the thickness of a germanium-silicon membrane. During a regular germanium-silicon membrane low-temperature epitaxial growth process, during arbitrary one step or a plurality of continuous processing steps before production of the germanium-silicon membrane, normal temperature gas is blown to a base seat bearing a silicon slice. The normal temperature gas does not contain gas capable of etching the base seat. According to the fact that a large amount of normal temperature gas is blown to the silicon slice base seat, the evenness of heat distribution of the silicon slice is improved, and the evenness of an inner face of the thickness of the germanium-silicon membrane growing in a follow-up mode is effectively improved. Therefore, the evenness and the yield of the inner face of product electrical parameters are improved.

Description

Improve the method for germanium silicon film thickness homogeneity

Technical field

The present invention relates to semiconductor integrated circuit and make the field, particularly relate to the method for a kind of improvement thickness homogeneity of the germanium silicon film of deposit on silicon chip.

Background technology

Germanium silicon is a kind of important semi-conducting material after silicon and GaAs, it has the superperformance that is better than pure silicon, and can be compatible with silicon on technique, simultaneously, the cost of germanium silicon is lower than GaAs, but the performance that adopts device that germanium silicon makes and circuit almost can reach the level of the compound semiconductor device such as GaAs and circuit, and therefore, the germanium silicon technology has become an important directions of microelectric technique development of new generation.

Heterojunction bipolar transistor (HBT) is a kind of SiGe device of most study, and take the device of NPN structure as example, its technological process is generally: first growth one deck N-type epitaxial loayer on mating plate, as emitter (collector); Then etching groove, and filling with dielectric layer forms STI (shallow trench isolation from), and active area (AA) is isolated; Then at the germanium silicon single crystal of active area growth one deck P type as base (base), at isolated area growth polycrystalline, then open a window at crystal region, and fill the N-type polysilicon of doping, form the structure of the similar triode of a NPN.For the device of positive-negative-positive structure, as long as in said method, n type material and P-type material exchange can be formed, operation principle is constant.

The quality of germanium silicon film growth (comprising the thickness, thickness homogeneity, doping content of germanium silicon fiml etc.) is most important to performance of devices.Impact (thermal budget) due to heat budget, the growth of general germanium silicon film is all to carry out under the low temperature of about 550～750 ℃, so kinetics plays a leading role in the growth course of germanium silicon fiml, the thickness of germanium silicon fiml is affected by temperature factor mainly.On pattern piece, because the area of active area is very little, generally below 1%, its heat conduction can be distributed in relatively rapidly the zone of full wafer silicon chip equably, the internal homogeneity of germanium silicon film thickness (WIWNU) can reach silicon chip face thickness homogeneity preferably by the power ratio of inside and outside circle heating lamp that adjustment is positioned at the upper and lower of epitaxial reaction chamber usually, as shown in Figure 1.but, for some product, in order to reduce costs, can be directly on the silicon mating plate in collector electrode (Collector district) deposit germanium silicon layer be used as base (Base district), because its actual active area is the full wafer silicon chip, fully different on its heat conduction situation and pattern piece, like this, power ratio by adjusting heating lamp is the more difficult homogeneity of improving germanium silicon film thickness just, and in germanium silicon fiml face, thickness evenness is relatively poor, may cause the current amplification factor difference of silicon chip centerand edge larger, can't satisfy the design specification of device, and have influence on yield.

Summary of the invention

The technical problem to be solved in the present invention is to provide a kind of method of improving germanium silicon film thickness homogeneity, and it can improve the internal homogeneity of the electrical parameter of semiconductor product.

For solving the problems of the technologies described above, the method of improving germanium silicon film thickness homogeneity of the present invention, the method is in the germanium silicon fiml low-temperature epitaxy growth technique of routine, in any one before growth germanium silicon fiml or a plurality of continuous step, blow the pedestal of carrying silicon chip with gas at normal temperature, do not contain in described gas at normal temperature can the described pedestal of etching gas.

The present invention is by before growth germanium silicon fiml, first blow the silicon chip pedestal with a large amount of gas at normal temperature, improve the uniformity that on the silicon chip, heat distributes, thereby effectively improved the internal homogeneity of the germanium silicon film thickness of subsequent deposition, and then improved internal homogeneity and the yield of product electrical parameter.In addition, the present invention need not to set up in addition gas piping, and it is convenient therefore not only to use, and can additionally not increase process costs.

Description of drawings

Fig. 1 is in reaction chamber, the existing process schematic representation of low-temperature epitaxy growth germanium silicon film on silicon chip.

Fig. 2 is the method schematic diagram that the embodiment of the present invention is improved the germanium silicon film thickness homogeneity of deposit on the silicon mating plate.

Fig. 3 adopts before and after the method for the embodiment of the present invention, the thickness comparison diagram of the germanium silicon film of growing on the silicon mating plate.

Fig. 4 adopts before and after the method for the embodiment of the present invention, after growth germanium silicon film on the silicon mating plate, and the current amplification factor comparison diagram of the wafer of measuring (respectively getting two wafer tests before and after improving).

Embodiment

Understand for technology contents of the present invention, characteristics and effect being had more specifically, existing in conjunction with illustrated execution mode, details are as follows:

Take low-temperature epitaxy growth germanium silicon fiml on the silicon mating plate as example, for the thickness homogeneity of the germanium silicon film that improves growth, in the arbitrary steps of the present embodiment before the growth of germanium silicon film, increase following steps:

With a large amount of gases under normal temperature (for example, hydrogen or nitrogen, but can not be to contain the easily gas of etching base material such as similar hydrogen chloride) that are in, blow to the pedestal of carrying silicon chip, as shown in Figure 2.

The flow of the reaction source gas the when flow of this gas at normal temperature will be grown much larger than the germanium silicon fiml generally can be controlled at 20～50 liter/mins of clocks.During logical gas at normal temperature, the pressure the when pressure in reaction chamber and the epitaxial growth of germanium silicon fiml in reaction chamber is consistent, and between 5～800T.The circulation pipeline of gas at normal temperature can use existing pipeline, namely for the set pipeline of gas injury that is not etched of protection base bottom in the germanium silicon fiml process of cleaning reaction chamber wall.

Above-mentioned steps can be before growth germanium silicon film any one step or a plurality of continuous processing step in carry out, carry out the impact effect to avoid variations in temperature too frequently but cannot intert in a plurality of discontinuous processing steps.

In existing silicon mating plate germanium silicon fiml low-temperature epitaxy growth technique, after introducing said method, the Temperature Distribution of pedestal has obtained obvious improvement, thereby improved Temperature Distribution in the face of silicon chip, and then improved the internal homogeneity of the thickness of the germanium silicon film that is deposited on silicon chip, (circle position) as shown in Figure 3, the germanium silicon film thickness of silicon chip edge obviously increases, the current amplification factor of the silicon chip after deposit germanium silicon fiml also be improved significantly, process window is wider, as shown in Figure 4.

In addition, need to prove, said method goes for the germanium silicon fiml low-temperature epitaxy growth technique of all reaction temperatures between 500～800 ℃, comprises the germanium silicon fiml growth technique on pattern piece.

Claims

1. improve the method for germanium silicon film thickness homogeneity, it is characterized in that, in the germanium silicon fiml low-temperature epitaxy growth technique of routine, in any one before growth germanium silicon fiml or a plurality of continuous step, blow the pedestal of carrying silicon chip with gas at normal temperature, do not contain in described gas at normal temperature can the described pedestal of etching gas.

2. method according to claim 1, is characterized in that, the flow of the reaction source gas of the flow of described gas at normal temperature during greater than growth germanium silicon fiml.

3. method according to claim 2, is characterized in that, the flow of described gas at normal temperature is 20～50 liter/mins of clocks.

4. method according to claim 1, is characterized in that, the pressure of reaction chamber is 5～800 holders.

5. method according to claim 1, is characterized in that, described gas at normal temperature is hydrogen or nitrogen.