CN101722159A

CN101722159A - Process for cleaning silicon chip by using diluted fluohydric acid

Info

Publication number: CN101722159A
Application number: CN200910242237A
Authority: CN
Inventors: 闫志瑞; 库黎明; 索思卓; 葛钟; 盛方毓
Original assignee: Beijing General Research Institute for Non Ferrous Metals; Grinm Semiconductor Materials Co Ltd
Current assignee: Beijing General Research Institute for Non Ferrous Metals; Grinm Semiconductor Materials Co Ltd
Priority date: 2009-12-04
Filing date: 2009-12-04
Publication date: 2010-06-09

Abstract

The invention discloses a process for cleaning a silicon chip by using diluted fluohydric acid, which comprises the step that the diluted fluohydric acid is used in the step of chemical reagent cleaning, namely the last step of the cleaning flow, wherein the volume ratio (HF to H2O) of the fluohydric acid to water in fluohydric acid cleaning solution is 1:300-1:2,000, and the cleaning time of the diluted fluohydric acid cleaning solution is between 30 and 1,000 seconds. The process has the advantages that the surface of the silicon chip cleaned by the process still is a hydrophilic surface, so adsorption phenomena of particles and part of metals caused by the conventional hydrophobic surface cleaned by DHF do not occur. By using the process, the metal contamination of the surface of the silicon chip after being cleaned by the process is less than 1E10atoms/cm2, and simultaneously the particle contamination degree (more than or equal to 0.10 micron) of the surface of the silicon chip can be less than 15 per piece, so the defects of the conventional cleaning solution in RCA cleaning are further overcome.

Description

The technology that a kind of hydrofluoric acid that uses dilution cleans silicon chip

Technical field

The present invention relates to the cleaning that a kind of hydrofluoric acid (DHF) that adopts dilution cleans silicon chip, specifically silicon chip is cleaned for the DHF solution that adopts super low concentration, under the prerequisite that the metal contamination that guarantees silicon chip surface is eliminated, make that the silicon chip surface after DHF cleans is still hydrophily.

Technical background

Be used for the silicon polished technological process of mostly adopting vertical pulling, section, abrasive disc, burn into polishing, cleaning, check of integrated circuit manufacturing at present.Wherein clean for the final step in the whole processing technology, so the quality of cleaning performance will directly be reflected in the customers' place.

The cleaning method that extensively adopts in the silicon chip manufacture process is standard RCA ablution and improved RCA ablution at present, and the chemical reagent that uses in this ablution mainly contains SPM (H ₂SO ₄/ H ₂O ₂), DHF, APM (NH ₄OH/H ₂O ₂/ H ₂O), HPM (HCL/H ₂O ₂/ H ₂O) etc.The main effect of SPM is to utilize H ₂SO ₄Strong oxidizing property organic contamination of removing silicon chip surface.DHF is used to remove the oxide-film of silicon chip surface, the passivation silicon chip surface, and the while can be removed Al, Fe, the metal contamination and the metal hydroxides such as Zn, Ni of silicon chip surface effectively; But along with oxide-film is dissolved in the cleaning fluid, noble metals such as a part of Cu (oxidation-reduction potential is than hydrogen height) can be attached to silicon face.APM can remove inorganic particle, organic deposition and the part metals contamination of silicon chip surface very effectively, and the dominant mechanism of removal is: the H among the APM ₂O ₂Can oxidized silicon chip surface, meanwhile NH ₄OH can erode oxide-film, and oxidation and corrosion are carried out repeatedly, and therefore the particle attached to silicon chip surface also falls in the cleaning fluid with corrosion layer; Owing to have oxide-film in the cleaning fluid or oxidation reaction takes place when cleaning, generate the big metal of the absolute value of free energy of oxide easily attached on the oxide-film, and then bring metal contamination.HPM is H ₂O ₂, the acid solution that mixes of HCL and water, it has extremely strong oxidisability and complexing, can generate salt with the metal function before the oxygen, be removed with deionized water rinsing then, the soluble complexes that oxidized metal ion and CL-effect generate also is removed with deionized water rinsing, so be mainly used in the metal contamination of removing silicon chip surface; Because the SiO of wafer surface ₂Can not be corroded with Si, therefore can not reach the effect of removing particle, can bring particle contaminant on the contrary.

By the pluses and minuses of above-mentioned various cleaning fluids as can be known, adopt the sort of technological process all can't realize perfect cleaning performance.For example the matting that adopts in traditional RCA cleans is APM → DHF → HPM, and HPM can remove the silicon chip surface metal contamination effectively, but can not get desirable surface particles state.

Summary of the invention

The purpose of this invention is to provide the technology that a kind of hydrofluoric acid that uses dilution cleans silicon chip, silicon chip surface metal contamination＜1E10atoms/cm2 after feasible the cleaning, simultaneously silicon chip surface particle degree of soiling (＞=0.10 micron) can＜15/sheet, and then solve RCA clean in the deficiency of conventional clean liquid.

To achieve the above object of the invention, the present invention is by the following technical solutions:

Use in the final step chemical reagent of cleaning process cleans, the volume ratio of hydrofluoric acid and water is HF: H in the hydrofluoric acid clean liquid ₂O=1: 300～1: 2000.The scavenging period of the hydrofluoric acid clean liquid of dilution is: 30 seconds---1000 seconds.

Silicon chip surface after this cleaning fluid cleans still is a water-wetted surface.

By obtaining desirable silicon chip surface state after this technology cleaning, the main former DHF of should be can remove the metal contamination of silicon chip surface effectively, meanwhile, because concentration of lotion is lower, use the silicon chip surface after this technology is cleaned still be water-wetted surface, do not clean the particle that back hydrophobic surface brings and the adsorption phenomena of part metals so traditional DHF can not take place.

The specific embodiment

Embodiment 1

Diameter 300mm, P＜100 that vertical pulling method is produced 〉, resistivity is 15-25 ohm. centimetre 125 of twin polishing sheets carry out final single-sided polishing, silicon chip behind the final single-sided polishing is divided into five groups (25 every group) cleans, the cleaning of employing is as follows:

First group: APM → DHF → APM → HPM → drying;

Second group: (dilution ratio is 1: 300 to the DHF of APM → DHF → APM → dilution for many times; Scavenging period is 30 seconds) → drying.

The 3rd group: (dilution ratio is 1: 300 to the DHF of APM → DHF → APM → dilution for many times; Scavenging period is 1000 seconds) → drying.

The 4th group: (dilution ratio is 1: 2000 to the DHF of APM → DHF → APM → dilution for many times; Scavenging period is 30 seconds) → drying.

The 5th group: (dilution ratio is 1: 2000 to the DHF of APM → DHF → APM → dilution for many times; Scavenging period is 1000 seconds) → drying.

Silicon chip after the cleaning carries out silicon chip surface particle laser scanning and the test of silicon chip surface metal contamination respectively, and the result is as follows:

Silicon chip surface particle laser scanning result:

(grain diameter:＞=0.10 micron; Unit: individual/sheet)

	Maximum	Minimum of a value	Mean value
	Maximum	Minimum of a value	Mean value	First group	??25	??11	??21.44
Second group	??13	??7	??10.64	First group	??25	??11	??21.44
Second group	??13	??7	??10.64	The 3rd group	??14	??6	??11.08
The 4th group	??10	??3	??7.08	The 3rd group	??14	??6	??11.08
The 4th group	??10	??3	??7.08	The 5th group	??11	??3	??8.24

Silicon chip surface metal contamination test result: (unit: E10atoms/cm2)

	??Na	??Al	??Ca	??K	??Fe	??Cr	??Cu	??Ni	??Zn
	??Na	??Al	??Ca	??K	??Fe	??Cr	??Cu	??Ni	??Zn	First group	??0.238	??0.235	??0.108	??0	??0.177	??0.028	??0.453	??0.672	??0.518
Second group	??0.346	??0.182	??0.100	??0	??0.280	??0.023	??0.354	??0.530	??0.540	First group	??0.238	??0.235	??0.108	??0	??0.177	??0.028	??0.453	??0.672	??0.518
Second group	??0.346	??0.182	??0.100	??0	??0.280	??0.023	??0.354	??0.530	??0.540	The 3rd group	??0.227	??0.165	??0.137	??0.108	??0.235	??0.019	??0.328	??0.496	??0.482
The 4th group	??0.351	??0.176	??0.148	??0.112	??0.263	??0.035	??0.317	??0.512	??0.493	The 3rd group	??0.227	??0.165	??0.137	??0.108	??0.235	??0.019	??0.328	??0.496	??0.482
The 4th group	??0.351	??0.176	??0.148	??0.112	??0.263	??0.035	??0.317	??0.512	??0.493	The 5th group	??0.294	??0.191	??0.213	??0	??0.301	??0.028	??0.345	??0.413	??0.473

From above result as can be known, the silicon chip surface metal contamination situation after two kinds of different cleanings are cleaned does not have tangible difference, but improves significantly than traditional handicraft through the silicon chip surface particle number after the DHF cleaning of dilution for many times.

Claims

1. a hydrofluoric acid that uses dilution is characterized in that the technology that silicon chip cleans: use in the final step chemical reagent of cleaning process cleans, the volume ratio of hydrofluoric acid and water is HF: H in the hydrofluoric acid clean liquid ₂O=1: 300～1: 2000.

2. the technology of cleaning according to claim 1, it is characterized in that: the scavenging period of the hydrofluoric acid clean liquid of dilution is: 30 seconds---1000 seconds.

3. the technology of cleaning according to claim 1 and 2 is characterized in that: the silicon chip surface after this cleaning fluid cleans still is water-wetted surface.